AutoForm Incremental

iletisim: [email protected]

ALGHAFORM PAYLASIMIDIR


www.forum.alghaform.com

www.alghaform.com

2 AutoForm–Incremental

AutoForm–Incremental is the AutoForm module to simulate sheet metal forming processes (conventional deep drawing, hydromechanical deep drawing) using the finite element method in many small steps. Using AutoForm–Incremental it is possible to simulate all forming operations beginning with the plane blank sheet and ending with the finished car body part including springback calculation. In AutoForm–Incremental the simulation of the following forming processes or phenomena is possible: • • • • • • • • • •

Impact of gravity when putting the blank sheet on the tool Binder closure (binderwrap) Drawing with/without drawbeads or lock beads Cutting Second forming Forming operations with cam slides Forming operations with die and punch inserts Springback Preforming the blank sheet by means of a fluid Hydromechanical deep drawing

Forming operations for steel and aluminum materials used in the automotive industry as well as tailored blanks can be simulated with AutoForm–Incremental. In connection with the easy–to–use user interface the tool maker, the tool designer and the process engineer can quickly verify the forming process in all tools and – where required – optimize processes, to lay the foundations for high quality parts at the computer. When entering the simulation input data, the user is guided by the program and pointed at still necessary inputs. The movement of all tools can be checked prior to the real simulation. In general the calculation time for a simulation ranges from only a some minutes up to a few hours. Color shaded post values such as sheet thickness, cracks, strain and stress as well as process parameters such as forces are available for the evaluation of the simulation. Wrinkles are identified by inspect-

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ing the shaded representation of the model or by means of color shaded post values. These possibilities are completed by additional special evaluation criteria such as skid/impact lines. In connection with AutoForm–Optimizer, the user gets access to a numerical optimization algorithm by which process parameters such as binder force or restraining forces for drawbeads are automatically modified during several simulation iterations to obtain an optimally stretched part without cracks and wrinkles.


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Contents of the Workshop „AutoForm–Incremental“ Lesson 1

Deep–Drawing on Double Action Press . . . . . . . . . . . . . . . . . 5 • • • • • • •

Lesson 2

Deep–Drawing on Single Action Press. Press. . . . . . . . . . . . . . . . . . . 27 • • • • •

Lesson 3

CAD–Import–IGES Positioning of tools Positioning the blank sheet Process definition Evaluation of the simulation

Drawbeads and Tailored Blanks . . . . . . . . . . . . . . . . . . . . . . . 47 • • • •

Lesson 4

CAD–Import–IGES Binder definition Input generator Blank definition Gravity Starting the simulation Evaluation of the simulation

Input generator Material definition Weld line Drawbead

Drawbead generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 • Automatic determination of the width • Automatic determination of the restraining force (Forcefactor) of a drawbead

Lesson 5

Tipping and Cutting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 • • • • •

Determination of the drawing direction Relief cut Trimming cut Holes Cutting direction


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Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 • • • •

Lesson 6

Numerical optimization Parameter study Optimization of the force factor of a drawbead Evaluating the optimization

Automatic Filleting with a Constant Radius . . . . . . . . . . . . . . 110

Lesson 7

• Automatic Filleting • Defining the blank sheet by arc • Restart Multiple Step process and Starting from Restart file . . . . . . . . 120 • • • •

Starting from Restart–File Definition of additional tools Definition of additional process steps Filleting radii

Using CAM Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 • • • • •

Lesson 10

Die insert (pad) Free contours, sharp edges and undercuts Definition of an additional tool Definition of additional process steps Altering tools Positioning of tools

Hydromechanical Deep Drawing . . . . . . . . . . . . . . . . . . . . . 173 • • • •

Lesson 9

Undercuts Adding tools Changing working direction Adding a process step Process type Flanging

Use of Pad and Springback. Springback. . . . . . . . . . . . . . . . . . . . . . . . . . 154 • • • • • •

Lesson 8

Lesson 11

Symmetry Forming by means of fluids Preforming Active hydromechanical deep drawing


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Lesson 1: Deep–Drawing on Double Action Press

2. 1 Lesson 1: Deep–Drawing on Double Action Press This lesson describes the deep–drawing process on a double action press. The CAD data of the die is available. Fig. 1.1

Deep drawing on a double action press

Generation of a Simulation file At the beginning, a new simulation file (*.sim) has to be defined. The first input is the name of the simulation. During the generation of the input, this simulation file is filled with data, which is necessary for the simulation (geometrical data, specification of process, numerical data etc.). The generation of the simulation file is done by the following input: File > New ... > in_lesson_01 > OK


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Lesson 1: Deep–Drawing on Double Action Press Fig. 1.2

Options to create a new simulation file • File name: name of *.sim file, without extension • Units: Units, which are used in this simulation file. This should correspond to units used in CAD data. • Geometric error tolerance: Acceptable chordal error of mesh generation.

Preparation of tool geometries for the simulation Normally the first input is the geometries of the tools used in this simulation. AutoForm requires these geometries in VDAFS or IGES format only. It is recommended that the user start with the input of the geometries, because possible errors or missing data in the CAD model can be checked and corrected early. The tool geometries are read in VDAFS– or IGES format. AutoForm automatically meshes the tool surfaces. All subsequent operations are based on this mesh. Only the mesh can be visualized in AutoForm, not the original CAD data.


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Lesson 1: Deep–Drawing on Double Action Press Import and meshing of CAD data File > Import > IGES > OK Fig. 1.3

Select a file: in_lesson_01.igs > OK Fig. 1.4

Window to mesh CAD data Start meshing with the option: Program: afmesh_3.1 > OK


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Lesson 1: Deep–Drawing on Double Action Press • Error tolerance: Acceptable chordal error for the meshing. Value is taken from New file dialog (Default: 0,1) (Fig 1.1), but it can be changed. For especially small radii (equal or lesser than 2 mm) 0.05 should be used as error tolerance. • Max side length: Maximum element side length

Parameters

• Treat only: Only specified faces will be meshed. • Exclude: The specified faces are not taken into account for meshing.

Faces

• Treat only: Only specified layers will be meshed. • Exclude: The specified layers are not taken into account for meshing.

Layers


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Lesson 1: Deep–Drawing on Double Action Press The meshed geometry is immediately displayed and the Geometry generator automatically pops up. At first, the tool setup in the Geometry generator has to be changed, so that the die is the lower tool (right Icon in Fig. 1.5). Fig. 1.5

In this example the CAD data is binder (binder) and punch (punch). Later the die (die) is created with Offset. The two tools have to be separated first. This is done as follows: Select faces of binder (right mouse button or Shift – right mouse button for several faces).


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Selected faces of binder Prepare

Define objects: Binder Binder is defined in Geometry generator and selected faces are put into the Binder register. The remaining unselected faces become the punch and all faces are defined as the die; hence all required tools for a standard simulation are now fully defined. The next step is checking the geometry to see if it can be used for simulation. AutoForm can check for free edges, sharp edges or undercuts. Control parameters can be found in Part boundary (Fig. 1.5): • Error tolerance is the acceptable chordal error of the CAD data describing the part boundary and the generated part boundary of AutoForm. • Concatenation distance is the minimum distance between points on the part boundary.


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Lesson 1: Deep–Drawing on Double Action Press Use button Generate part boundary: Apply (Fig. 1.5 bottom right) to start automatic calculation of the part boundary (shown in blue). Fig. 1.7

Generated part boundary If gaps occur in the geometry, several blue lines are displayed. This is one possible way of checking for gaps and untrimmed surfaces. If the generated part boundary needs to be changed, it can be done using the option Prepare

Outer Trim > Edit Holes can be created with the option Inner Trim > Add… Correction of untrimmed surfaces should be performed in CAD system. Checking for sharp edges and undercuts can also be done in Geometry generator. This is described in detail in Lessons 5 and 7.


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Lesson 1: Deep–Drawing on Double Action Press Check geometry for sharp edges: Fillet

Geometry generator > Fillet > Check radius: 2.00 > Check In the log–window, it is displayed that (no) sharp edges have been found. Close the window using Dismiss (Fig. 1.8).

Fig. 1.8

Fillet page of Geometry generator


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Lesson 1: Deep–Drawing on Double Action Press Check geometry for undercuts using option: Geometry generator > Tip (Fig. 1.9) Fig. 1.9

Tip page of Geometry generator All undercuts, marginal areas and undercut free areas are calculated and displayed in different color for the current drawing direction when the Tip page is opened. Undercut free areas are displayed in green, marginal areas are displayed in yellow and undercuts are displayed in red. This colored display can be chosen with the option Tip

Display > Backdrafts in the Geometry generator. www.forum.alghaform.com

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Lesson 1: Deep–Drawing on Double Action Press Use the button Plot to activate the backdraft diagram (Fig. 1.9).

Generate simulation input All further inputs are defined in the Input generator. Open the Input generator: Model > Input generator ... > Simulation type: Incremental Fig. 1.10

Dialog: Simulation Type to create simulation input • Simulation type: Incremental simulation, OneStep simulation or Hydroforming of tubes • Tool setup: Defines the tool setup with respect to z–axis (z– axis points upward) • Sheet thickness: sheet thickness • Geometry refers to: Decide which side of the tool set the geometry refers to (punch side or die side). • No offset: None of the tools automatically gets an offset. In this case, tool offsets should be created in CAD system and different CAD geometries for punch and die should be read in. The current file contains binder and punch geometry. Therefore, the die gets an offset (Geometry refers to: punch side). OK opens Input generator.


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Lesson 1: Deep–Drawing on Double Action Press Page Title (title of simulation) has a default text–string input which can be changed. Comments is for the input of user–comments regarding the current simulation. All inputs for the simulation need to be completed before it can be executed: Inputs are missing on pages that are marked conveniently with red letters. Fig. 1.11

Input generator The input on pages shown in black letters are already completed. Nevertheless, all input data should be checked for meaningful values for current simulation. In the following example, only pages marked with red letters are considered. Tools

Tools are defined on Tools page. Three tools (die, punch and binder) have already been defined. The geometries of these tools have been defined in the preparation phase of tool geometries for the simulation.


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Lesson 1: Deep–Drawing on Double Action Press Binder is marked in red on this page, because columns for the binder must be defined. Columns are the input points of the force for force–controlled tools. By default, the binder is predefined as being a force–controlled tool. Therefore AutoForm requires this input (see also Lessons 8 – 10). Columns have to be defined for every force–controlled tool. Columns for binder: It is recommended to use Tool center Option Rectangle ... on Blank page defines a rectangular blank outline.

Blank

Tip: Tip We recommend a view from positive z–axis (press Ctrl–Z Ctrl Z). Fig. 1.12

Blank page of Input generator Outline > Rectangle ... www.forum.alghaform.com

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Lesson 1: Deep–Drawing on Double Action Press Menu Blank outline - Rectangle opens: Fig. 1.13

Blank outline - Rectangle Inputs can be done by using either the right mouse button or keyboard. Use the right mouse button and sketch a rectangle to define a rectangular blank outline. The blank outline (blue) is displayed in the main display (Fig. 1.14). In the menu Blank outline - Rectangle (Fig. 1.13) modify the values as follows: Blank

Center x, y: 0, 0 Length X: 430 Length Y: 340

Fig. 1.14

Rectangular blank outline Complete the definition of the blank outline by selecting OK www.forum.alghaform.com

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Lesson 1: Deep–Drawing on Double Action Press A double action deep–drawing process is already predefined on the Process page. Double action deep–drawing process means that the binder moves until it closes with the die and then the punch moves until it is fully bottom down. The duration of the different process steps (Duration on Process page) depends on the positioning of the tools with respect each other (Move on Tools page). By default, the distances between the tools are 500 mm.

Process

Fig. 1.15

Process page of Input generator For this example only inputs for process step named gravity are missing (Fig. 1.15): gravity > Gravity: downwards die: Stationary


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Control – Input of numerical parameters

Control page of Input generator For sheet thickness greater than 1.5 mm: select ThickSheet/Springback in later restart Tip: Tip If button ThickSheet/Springback in later restart is activated, the simulation is done using 5 layers. In addition to the preselected result variables, the following are selected: Rslts > Contact distance above Rslts > Contact distance below Rslts > Curvature Start of simulation Job > Start simulation ... > Start job > Program: af_3.1 > Start www.forum.alghaform.com

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Start Job window Only one simulation can be started with one license. Other simulations that are ready to start can be put into a queue (Queue). The simulation job can be put at the top or bottom of the queue. Kinematic check only checks the tool movement only. This is completed in a few seconds. This functionality helps avoid possible errors of the tool movement or tool positioning and is recognized during the simulation. If this button is activated, only the tool movements are calculated and displayed. The blank remains undeformed. The results are saved in the simulation file after start of the calculation (Kinematic check only not activated). File > Reopen opens the *.sim file again, and results can be analyzed. At each time–step of the analysis, the Input generator can be opened to review or change the input or define another simulation because the input data is also saved in the *.sim file as the results. www.forum.alghaform.com

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Lesson 1: Deep–Drawing on Double Action Press

Analysis of results (colored display of result variables) In the following the analysis of the most important result variables will be discussed. These results can be displayed both as colored and shaded images. Re–open the simulation file (*.sim) after the calculation is completed successfully. File > Reopen To go to the end of the simulation use Time > End of simulation or hotkey Ctrl – E. Moving the mouse over the icon panel on the right side of the main display shows the names of each of the icons. Activate the display of Formability results with button Formability (shown in second row of result buttons in main display). Fig. 1.18

Result variable Formability www.forum.alghaform.com

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Lesson 1: Deep–Drawing on Double Action Press • Cracks: Areas of cracks. These areas are above the FLC of the specified material. • Excess. Thinning: In this area, thinning is greater than the acceptable value (default value for steel is 30%). • Risk of cracks: These areas may crack or split. By default, this area is in between the FLC and 20% below the FLC. • Safe: All areas that have no formability problems. • Insuff. Stretching: Areas that have not enough strain (default 2%) • Wrinkling tendency: Areas where wrinkles might appear. In these areas, the material has compressive stresses but no compressive strains • Wrinkles: Areas where wrinkles can be expected, depending on geometry curvature, thickness and tool contact. Material in these areas has compressive strains which means the material becomes thicker during the forming process. In this example, wrinkles can be expected in the center of the part geometry and in the binder area. The part does not show any cracks or excessive thinning. The default–values of result variable Formability can be changed in the following menu: Results > Formability … Fig. 1.19

Dialog: Formability The small plot shows the different areas with respect to the FLC.


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Lesson 1: Deep–Drawing on Double Action Press Switch to result variable Thinning (second row of icon panel in main display, middle button). A scale is displayed in the lower part of the main display with a range of 30% thinning to 3% thickening colored from yellow to green (depending on the specified color settings). The exact thinning value (in percentage) is displayed, when you click with the right mouse button on the geometry. Hit the Esc key to clear these labels from the display. To find the maximum thinning and the maximum thickening of the part use the following options (Fig. 1.20) Results > Show max Results > Show min Fig. 1.20

Display of result variable Thinning with min and max values To change the displayed range of the scale use the following option (Fig. 1.21) Result > Ranges


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Dialog: AutoForm - Min/Max Editor • Min/Max Simulation: Use min and max values of the whole simulation. • Min/Max Increment: Use min and max values of the current increment. • Simulation default: Use default min and max values. • Manual: Use user–defined min and max values. Change the values for the scale manually: Manual: Min. 0.0 Max. 0.05 The display should correspond to Fig. 1.22. All areas without thickening are displayed in yellow.


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Display of result value Thinning with min value 0.0 and max value 0.05 Switch to result variable Failure (maximum) (first row of icon panel in main display, middle button). Deactivate the display of the min value with following option (Fig. 1.23) Results > Show min


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Display of result value Failure (maximum) with max value No values > 0.8 are shown for this example. This means that no cracks can be expected for the deep drawing of this part.

Close AutoForm–User Interface The user interface can be closed with following option: File > Quit or hotkey Ctrl – Q.


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Lesson 2: Deep–Drawing on Single Action Press

2. 2 Lesson 2: Deep–Drawing on Single Action Press In a single action press, the die is mounted to the ram of the press. Punch and binder are mounted on the press table. The blank lies on the binder. Sometimes the punch supports the blank, to avoid bending of the blank due to gravity. During the forming process the ram moves down and at first the die closes with the binder and the blank is fixed between these tools. The die then displaces with the binder during the ongoing movement of the ram and the part is formed over the fixed punch. The position of the tools is shown in Fig. 2.1. Fig. 2.1

Tools in a single action press The tool setup is the opposite of setup for deep drawing on double action presses (see Lesson 1). For an AutoForm simulation a double action deep drawing process is predefined by default. This can be changed to a single action process. One has to adjust • Tool positioning (Tools page of Input generator) • Initial position of blank (Blank page of Input generator) and • Process steps (Process page of Input generator) www.forum.alghaform.com

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Lesson 2: Deep–Drawing on Single Action Press Keep in mind that for a single action process, tool geometry is always taken from CAD. In nearly all cases only one side of the tool exists and the other side is generated in AutoForm with Offset option. This means that the initial position of the tools is the same. At first the tools are opened (Tools page) and during the forming process they are closed (Process page). For a double action process the distance at which the tools are opened does not matter because in AutoForm the tools always move in a single increment until initial sheet contact is made. Subsequently, the incremental displacements are used only during the forming of the sheet. Using a double action process, the tools move until contact with the sheet is made without any movement of the sheet itself. The initial positioning of the tools has to be such that there is no penetration between the tools and blank. In a single action process the positioning of the tools is very important. The distance of binder and punch has to reflect the real distance in the press. The distance between binder and die does not influence the simulation. The reason is that the blank lies on the binder and the die moves initially until it comes into contact with the sheet. During drawing, the die displaces both binder and sheet and due to this movement of the sheet, AutoForm uses the incremental displacement. If the distance between binder and punch is too large, it can lead to long calculation time and unrealistic results. Therefore it is important that the tool positioning for a single action process in AutoForm simulations should be the same as in the real press.

Preparation of simulation Open a new simulation file: File > New ... > in_lesson_02 > OK Geometry generator opens. File > Import ... > IGES > OK > in_lesson_02.igs > OK > Program: afmesh_3.1 > OK Prepare > Select faces of binder (right mouse button) (Fig. 2.2).


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Lesson 2: Deep–Drawing on Single Action Press Fig. 2.2

Geometry with selected binder patches Prepare > Define objects: Binder Now the selected patches are defined as binder, unselected patches are defined as punch and all patches are defined as die. Check geometry for gaps: Geometry generator > Generate part boundary: Apply Check geometry for sharp edges: Geometry generator > Fillet > Check radius: 2.00 > Check A message that (no) sharp edges have been found appears in the log–window. Close this log–window with Dismiss. Check geometry for undercuts: Geometry generator > Tip All undercuts, marginal areas and undercut free areas are calculated and color displayed for the current drawing direction when Tip page is opened (see Lesson 1 for a detailed description of Tipping options). Undercut free areas are displayed in green, marginal areas are displayed in yellow and undercuts are displayed in red. This colored display can be switched on or off with the option Display > Backdrafts in the Geometry generator. www.forum.alghaform.com

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Lesson 2: Deep–Drawing on Single Action Press Use button Plot to activate the backdraft diagram (see Lesson 1 for more details).

Generate simulation input Model > Input generator ... > Simulation type: Incremental > OK Title is predefined but it can be changed. Columns for binder has to be defined on Tools page. It is recommended to use: Tool center Option Rectangle ... on Blank page defines a rectangular blank outline. Inputs can be made by either using the right mouse button or keyboard. Use the right mouse button and drag a rectangle to define a rectangular blank outline. The blank outline (blue) is displayed in the main display (Fig. 2.3). In menu Blank outline – Rectangle modify the values as follows:

Blank

Center x, y: 0, 0 Length X: 430 Length Y: 340 Fig. 2.3

Rectangular blank outline Finish the definition of the blank outline with OK


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Lesson 2: Deep–Drawing on Single Action Press

Adjust input for a single action process All changes are done in Input generator. Modification of tool position (Tools page) The tool position has to be changed for a single action process. The punch is fixed on the press table. Therefore it is recommended to use punch position as reference. punch > Working direction > Move: 0 (Fig. 2.4). Fig. 2.4

Position punch Binder should be moved by 65 mm in working direction (Fig. 2.5). It is positioned slightly above the punch to avoid excessive bending of the sheet due to gravity. In AutoForm, the working direction is always defined with respect to the blank. It is calculated automatically, if the tool setup is correctly defined on the Prepare page of Geometry generator. www.forum.alghaform.com

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Position binder Any position of the die can be chosen but it is important that the die and the sheet do not intersect. In this example, the position of the die is chosen as being 565 mm opposite to working direction. die > Working direction > Move: -565 (Fig. 2.6). This value is used to allow 500 mm for the closing of the die and binder + 65 mm for forming.


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Position die These adjustments lead to following initial tool position (Fig. 2.7):


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Initial position of tools Modification of initial position of blank (Blank page) The initial blank position can be modified on Blank page. For a double action process, the blank is positioned on the die. This is the AutoForm default. For a single action process, the blank has to be positioned on the binder. Input generator > Blank > Position > On: binder (Fig. 2.8)


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Blank page: Blank is positioned on binder. Use material Zste180bhZ_1 from the database with thickness 1.0 mm: Input generator > Blank > Properties > Thickness > 1.0 Warning: Tool offset adapted due to new average blank thickness. Select OK. Input generator > Blank > Properties > Import ... > Steel_General+Europe > zste180bhZ_1.mat > OK Lube

Here the friction coefficient between sheet and tools can be specified. By default (Standard), a single value of the friction coefficient is used for all sheet/tool contacts. It is recommended to use 0.15 for sheet–steel and 0.18 for aluminum. Different friction coefficients can be specified for tools above and below the sheet or for each of the sheet/tool contacts (Fig. 2.9). www.forum.alghaform.com

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Lube page: Definition of friction coefficient – Standard 0.15 Modification of process steps (Process page) Two modifications have to be made on Process page: • tool movements and • duration of process steps. gravity > Gravity: Downwards > Tool control > Show all > die: Non-active > punch: Stationary > binder: Stationary (Fig. 2.10)

Gravity


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Input page for gravity Binder Wrap

During binder wrap, the die is moving towards the binder and the binder and the punch are stationary. closing > Tool control > Show all > die: Displcmnt > Velocity: 1 > Set punch: Stationary > binder: Stationary Duration of a process step depends on the distance of the contacting tools (see Tools page). In this example, the distance between the die and the binder (500 mm) determines the duration: Duration > During time > Time: 500 (Fig. 2.11)


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Input for binder wrap (closing closing) closing During the drawing process, the die is moving towards the punch, the binder is force–controlled and it is displaced by the die. The punch is stationary.

Drawing

drawing > die > Displcmnt > Velocity: 1 > Set > punch: Stationary binder > Force > Relative tool: die > Const pressure > Value: 3 > Set Duration of this process step depends on distance between punch and binder (65 mm): Duration > During time > Time: 65 (Fig. 2.12)


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Input for drawing process step Job > Start Tool movement can be checked with option Kinematic check. If the punch should support the blank during gravity, the binder position must be changed on the Tools page and duration of the drawing process step (drawing) must be changed on the Process page. Start the Simulation Job > Start simulation ...

Analysis of the simulation results (part2 – punch contact, wrinkles, skid lines, sections, FLD, tool forces) When the calculation is finished, reopen the simulation file (*.sim) with www.forum.alghaform.com

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Lesson 2: Deep–Drawing on Single Action Press File > Reopen Punch contact In order to ensure that deep drawn parts have a high level of quality after deformation, it is important for them to have uniform initial punch contact, especially for outer panels. This can be checked as follows: Display > Fill styles > Tools: Filled mesh > Sheet: Filled Activate display of the punch: click the button punch in the user interface (right side, below the buttons for sheet, blank and geometry). Set time to the end of binder wrap (closing). Time > closing Modify the display by clicking with the left mouse button in the scale area right of the slider and then click the right mouse button twice (Time 512). The punch is visible through the sheet and initial punch contact can be analyzed. Fig. 2.13


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Lesson 2: Deep–Drawing on Single Action Press Wrinkles It is necessary to visualize the sheet in shaded mode and to display all increments (animation) to analyze wrinkling during drawing process. Some increments have to be analyzed in detail if wrinkles occur. Deactivate the display of the punch (select the punch button in the main display again). Start the animation of the drawing process: Time > Animate start or use hotkey Ctrl – A If a single increment needs to be analyzed in detail, stop the animation using Ctrl – A. You can also use menu option Time > Times … and then select one of the available increments in the Time menu. A surface deviation can be seen in Fig. 2.14. Fig. 2.14

Surface deviation of 10 mm before bottom down


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Lesson 2: Deep–Drawing on Single Action Press Skidlines Skidlines occur, if the sheet is drawn over small radii of the tool with a certain contact pressure at a certain contact angle. Areas where skidlines occur are normally in drawing radius regions. Skidlines can be visualized with the following option: Results > Tool marks In menu AutoForm - Toolmarks File > Read from File > in_lesson_02_toolmark.af > OK Tools > Project onto > die > Accept Define > Skid/Impact line File > Dismiss Use menu option Time > Simulation end or hotkey Ctrl – E to go to simulation end. Skidlines are now displayed as blue lines and the movement and position of these lines can be analyzed (Fig. 2.15). Fig. 2.15

Visualization of skid lines at simulation end The display can be deactivated with following option: Results > Skid/Impact line … > Select line with left mouse button > Display > Clear all > File > Dismiss Sections Sometimes it is necessary to analyze the sheet/tool contact with dynamic sections. Activate display of all tools www.forum.alghaform.com

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Lesson 2: Deep–Drawing on Single Action Press Display > Tools … > Show all Use hotkey Ctrl – D to open Dynamic section menu. Define a section plane (Fig. 2.16) A x y: -200, 0 B x y: 200, 0 and select option Section in Dynamic section menu: • Option Section displays the selected section plane as a 2D– curve • Option Clipping displays 3D geometry with the selected section plane as a clipping plane. Fig. 2.16

Dynamic section menu with defined section plane and activated option Section Press the button Apply in the Dynamic section menu. The 2D section is displayed in the main display (Fig. 2.17). Fig. 2.17

Dynamic section with option Section displayed in the main display www.forum.alghaform.com

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Lesson 2: Deep–Drawing on Single Action Press Deactivate Dynamic section with the option: Dismiss Deactivate the display of all tools: Display > Tools … > Clear all Forming Limit Diagram (FLD) The Forming Limit Diagram (FLD) is a method to predict material failures. The Forming Limit Curve (FLC) (measured strains above which cracks occur) is displayed in black in the FLD. Major/minor strains of all finite elements are shown in this diagram. Cracks and process stability can now be analyzed. This diagram is activated with the option: Results > FLD then Time > Simulation end or hotkey Ctrl – E to go to the simulation end. Strains of all elements are displayed in the FLC diagram by selecting the Show all button (top right – see Fig. 2.18). In this example all elements are far away from the FLC, which means that no cracks or splits are predicted and the process is quite stable.


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Forming Limit Diagram with all elements displayed at the simulation end Deactivate the diagram with Dismiss Forces Tool forces are of great interest for the forming simulation analysis. In this example, the display of the punch force over punch stroke is described. Keep in mind that the calculated force is only a rough estimation of the actual force, because friction forces of the press and coining effects are not taken into account. As a rule of thumb, the calculated forces should be multiplied with a factor of 2 to 2.5 for the actual force. Activate AutoForm - Process data menu with option: www.forum.alghaform.com

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Lesson 2: Deep–Drawing on Single Action Press Results > Process data … Deactivate forces for the die and binder: Calculated reaction forces > die Calculated reaction forces > binder A calculated punch force of about 300000 N is necessary at bottom down (Fig. 2.19) to form the part. This would mean in reality a punch force of about 75 tons. Fig. 2.19

Calculated punch force over process time Deactivate the menu with Dismiss



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Lesson 3: Drawbeads and Tailored Blanks

2. 3 Lesson 3: Drawbeads and Tailored Blanks This lesson mainly covers drawbeads and tailor–welded blanks. In AutoForm you can define any number of drawbeads or weld lines. Fig. 3.1

Drawbeads (red lines) and weld lines (blue lines)

Tailored Blanks In AutoForm you can define any number of weld lines. This definition is done in the Input generator. Weld lines can have the following shapes: • Simple joint (weld line from one blank boundary to another blank boundary) (Weld line 1 in Fig. 3.1) • T–joint (weld line from weld line to blank boundary) (Weld line 2 in Fig. 3.1) and • Patch (closed weld line, patch is welded into a blank) (Weld line 3 in Fig. 3.1) A new simulation is created for this lesson, similar to Lesson 1.

Generation of a Simulation file The generation of the simulation file is done with the following input: File > New ... > in_lesson_03 > OK


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Lesson 3: Drawbeads and Tailored Blanks

Preparation of tool geometries for the simulation Reading and meshing CAD model: File > Import ... > VDAFS > OK > in_lesson_03.vda > OK > Program: afmesh_3.1 > OK The meshed geometry is immediately displayed and the Geometry generator automatically pops up. At first the tool setup in the Geometry generator has to be changed, so that the die is the lower tool (right icon in Fig. 3.2). Fig. 3.2

Prepare page of the Geometry generator


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Lesson 3: Drawbeads and Tailored Blanks Now the binder has to be defined in order to separate the geometry into punch, die and binder. Select faces of binder (right mouse button or Shift + right mouse button for several faces). Fig. 3.3

Selected faces of binder Prepare > Define objects: Binder All tools are now defined (see Lesson 1 for details). Now the blank boundary has to be generated. Use the button Generate part boundary: Apply (right bottom in Fig. 3.2) to start automatic generation of part boundary. Part boundary is displayed in blue (Fig. 3.4).


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Lesson 3: Drawbeads and Tailored Blanks Fig. 3.4

Generated part boundary Check geometry for sharp edges: Geometry generator > Fillet > Check radius: 2.00 > Check In the log–window it is displayed that (no) sharp edges have been found. Close this window using Dismiss. Check geometry for undercuts using option: Geometry generator > Tip All undercuts, marginal areas and undercut free areas are calculated and displayed in different color for the current drawing direction when the Tip page is opened (see Lesson 1 for more details on using the Tip function). Undercut free areas are displayed in green, marginal areas are displayed in yellow and undercuts are displayed in red. This colored display can be chosen with the option Display > Backdrafts in the Geometry generator. Use the button Plot to activate the backdraft diagram.

Generate simulation input All further inputs are defined in the Input generator. Open the Input generator: Model > Input generator ... > Simulation type: Incremental > OK Binder is marked in red on this page, because columns must be defined.

Tools


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Lesson 3: Drawbeads and Tailored Blanks Columns for binder: It is recommended to use Tool center Blank

Outline > Copy from... > Select curve (Fig. 3.5) > Bndry (Pre) 1 > OK This option on Blank page creates a blank outline which is identical to the part boundary (Fig. 3.4).

Fig. 3.5

The menu Select curve shows all generated lines – here the part boundary should be selected to generate a blank boundary that is identical to the part boundary. Edit the blank boundary now: Outline > Edit ... > Curve editor (Fig. 3.6) > Global mod > Convex > move slider to max. value (right side) > Expand: 40 > OK Fig. 3.6

Settings on Global mod in Curve editor–menu editor Definition of a weld line

On the Blank page, several modifications have to be made to define a tailor–welded blank. Weld lines are always added in lower section of the Blank page (Fig. 3.7). www.forum.alghaform.com

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Blank page: Add weld ... Weld menu opens, for which inputs have to be completed. Fig. 3.8

Weld menu www.forum.alghaform.com

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Lesson 3: Drawbeads and Tailored Blanks Options for generating a tailor–weld blank: • Weld line: Position and orientation of the weld–line is defined here. • Properties: These are the properties of one part of blank, which can be changed in comparison to the basic or reference blank (At least one of these properties has to be changed.). • Thickness: Thickness of the blank • Material: Material of the blank • Angle: Rolling direction • Properties apply at: A right mouse button click on one of the blank regions, which are joined with the weld line, defines the region for which the new properties (i.e., thickness, material and angle) are valid. Weld line > Input… > Curve editor > Define weld line with right mouse button (the start– and end points lie on the blank boundary) > OK Weld line is accepted (Fig. 3.1 – Weld line 1). A weld line joins two different parts of a blank. Properties of one part of blank are already defined on Blank page. Properties for the other part of the blank have to be defined on the Weld page. In this example the thickness of the two halves is different (0.8 mm and 1 mm): Properties > Thickness: 1 (Fig. 3.9) Fig. 3.9

Definition of new thickness www.forum.alghaform.com

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Lesson 3: Drawbeads and Tailored Blanks Click > A right mouse button clicks on the blank region, for which the new properties are valid (right part) > OK After pressing OK button, a dialog (Fig. 3.10) asks if the automatic tool offset should be calculated based on the average thickness. Fig. 3.10

Dialog to adjust automatically offset to average thickness OK – (on Tools page the offset is 0.9 =(0.8+1.0)/ 2) (Fig. 3.11). Fig. 3.11

Tools page – new offset is automatically used To define a second weld line, select the Add weld ... button on the Blank page again (Fig. 3.7). The Weld–menu appears again. Now the properties of the second weld line have to be completed.

Definition of a T– Joint

Add weld ... on Blank page Weld line > Input > Define weld line using right mouse button (start point lies on the first weld line and the end point lies on the blank boundary) (Fig. 3.1 – Weld line 2) > OK Properties > Thickness: 2 (Fig. 3.12) Click > A right mouse button click on the blank region, for which the new properties are valid > OK


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New thickness will be defined Again the dialog appears which asks if the automatic offset should be calculated as the mathematical average of the three thickness values (see Fig. 3.10) OK – on Tools page the offset is 1.2667 – ((0.8 + 1 + 2) / 3) Definition of a closed weld line (patch–work)

Menu to add a weld line Add weld ... on the Blank page Weld line > Input > Define a closed weld line using the right mouse button (Fig. 3.1 – Weld line 3) Properties > Material > Import ... > zste180bhZ_1.mat > OK (Fig. 3.13) Click > A right mouse button click on the blank region, for which the new properties are valid (new material) > OK


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The new material will be defined Using this procedure, any number of weld lines can be defined for a simulation. After launching the simulation, AutoForm will create the blank and the properties of the defined areas can be examined. This examination is not possible prior the launch of the simulation since (before the simulation) only the boundaries are defined and the blank does not exist yet.

Drawbead In AutoForm a drawbead is defined using only a bead center–line and not with the real bead–profile geometry. This line specifies the position of the drawbead. Furthermore a restraining force is specified which depends on the real profile geometry. It is also possible to use the geometry of the drawbead, but that is not recommended. Advantages of the drawbead model are: • Simulation time is shorter, because the drawbead geometry with its small radii does not need to be geometrically formed by the mesh (hence fewer elements are necessary). • Changes or optimization of the drawbead position or drawbead force can be achieved easily and quickly within AutoForm directly. In contrast, changes to the real profile geometry of the drawbead have to be made in a CAD system which takes much more time and effort.


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Lesson 3: Drawbeads and Tailored Blanks AutoForm now offers a Drawbead generator for the correlation of the real profile geometry of drawbeads and drawbead force. With the Drawbead generator the real geometry of the drawbead can be specified and the force factor is automatically calculated by AutoForm. If the force factor is known, the Drawbead generator will determine the real geometry of the drawbead. Use of the Drawbead generator is described in Lesson 4. Fig. 3.14

To define a draw bead an additional page has to be added to the Input generator. Add > Drawbead ... (Fig. 3.14) > Add drawbead > OK A new page is added to Input generator (Fig. 3.15).

Fig. 3.15

Drawbead page (Drwbds Drwbds) Drwbds


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Lesson 3: Drawbeads and Tailored Blanks Functions for generating a drawbead: • Name: Name of a drawbead can be specified. • Tools: Tools are defined; drawbead is active when these tools are closed. • Input ...: Position of drawbead line can be specified (Curve editor). • Import ...: Drawbead line is imported from CAD. • Copy from ...: Drawbead line is copied from an existing line. Base line and drawbead line are treated as different lines. • Dependent ...: Drawbead line is created from an existing line. Drawbead line is a reference to the base line. This means only the base line can be changed and the dependent drawbead line will also change correspondingly. • Position: Displacement of drawbead line in x–y plane • Width: Width of a drawbead • Forcefactor: Force factor of a drawbead Drwbds > Name: bead1 > Above: binder > Below: die Drawbead line > Input ... > Define drawbead line using the right mouse button (Fig. 3.1 – bead 1) (For symmetrical parts drawbead lines should intersect the symmetry line) > OK Width: 15 Forcefactor: Medium: 0.35 An additional page has to be opened on the Drwbds page to add a second drawbead. This can be done in the Input generator with the menu option: Add > Drawbead ... > Add drawbead > OK or on Drwbds page using button Add Drawbead ... (Fig. 3.15 left lower corner) > OK A dialog asks if the new drawbead should be generated with parameters of an existing drawbead. Fig. 3.16 shows that parameters of bead1 are used. Only the drawbead line has to be specified for bead 2. All other input parameters are automatically taken from bead 1 (Fig. 3.17).


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Dialog asking for reference beads Fig. 3.17

Only the line needs to be defined for the second bead The position and length of the second drawbead line will be defined using existing part boundary (Bndry (Pre)1). Drawbead line > Copy from ... > Select curve > Bndry (Pre) 1 (Fig. 3.18) > OK

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Select curve curve–menu The second drawbead line is modified: Drawbead line > Edit ... > Curve editor > Global mod > Expand: 20 > Trim (Fig. 3.20) (Length of a drawbead will be defined. Start point is defined using the right mouse button (Fig. 3.21) and end point is defined using Shift – right mouse button (Fig. 3.22)) > OK Fig. 3.19

Drawbead line is expanded on the Global mod mod–page in Curve editor–menu. Fig. 3.20

Trim page in Curve editor–menu editor www.forum.alghaform.com

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Start point of a drawbead line Fig. 3.22

End point of a drawbead line Process

Only inputs for process step gravity are missing on Process page (Fig. 3.23): Process > gravity > Gravity: Downwards Tool control > die: Stationary


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Definition of process step gravity Control – Input of numerical Parameter WriteRestart > off (Fig. 3.24) WriteRestart ON means that a restart file (*.rst) is created. This file contains all data that is necessary to restart the simulation from a particular time. Restarts can be used to save time, e.g. for multi stage processes, the different forming processes can be simulated one after the other. The disadvantage is the size of the *.rst file which requires greater disk space. Taking into account the speed of AutoForm, the restart option is only useful for large parts (e.g. side panel, floor panel). In Lesson 8 (Multiple Step process and Starting from Restart File), this option is described in complete detail. www.forum.alghaform.com

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Control page of Input generator – WriteRestart disabled Following results variables are switched off on Rslts page: Rslts > Contact distance above Rslts > Contact distance below Rslts > Curvature Start of simulation Job > Start simulation ... > Start job > Program: af_3.1 > Start File > Reopen …


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Lesson 4: Drawbead generator

2. 4 Lesson 4: Drawbead generator This lesson describes in detail how the width, the force factor and the restraining forces of a drawbead are determined automatically. The values are determined in the Drawbead generator and have to be input manually in the Input generator. Drawbead generator calculates the values Width and Forcefactor for a defined drawbead. These are dependent on • • • • •

geometry of the drawbead, sheet thickness, friction, forming velocity and material

These two values have to be specified manually in the Input generator (Drawbead page > Width and Forcefactor). Warning: Warning The function is currently a Beta–Version. This is mainly due to insufficient comparisons between the results of Drawbead generator and actual stampings at present. First a simulation file has to be created to use the Drawbead generator, as was done in previous lessons. Open example simulation file in_lesson_04.sim: File > Open ... > Select a file > in_lesson_04.sim > OK The drawbead generator is opened with Model > Drawbead generator ...

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Lesson 4: Drawbead generator Fig. 4.1

Drawbead generator First the name of the drawbead is necessary (Name:). This name has to be the same as the drawbead defined in the Input generator. Then the type of drawbead has to be specified. The Drawbead generator offers three options: drawbead, lock bead and lock step. The drawbead type is specified with the buttons shown in Fig. 4.2. Menu for selecting drawbead, lock bead or lock step Fig. 4.2 www.forum.alghaform.com

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Lesson 4: Drawbead generator Different geometrical parameters are necessary for the different drawbead types.

Drawbead geometry (Shape)

Drawbead A drawbead is defined with the following parameters (Fig. 4.3): • • • •

Radius R: Draw in radius Height h: Height of drawbead Radius r: Radius of drawbead Clearance c: Clearance

These parameters can be changed graphically by moving the dashed lines (Fig. 4.3) or directly with the input fields for the parameters. The dashed lines can be moved with the left or right mouse button. Use the middle mouse button to zoom in and out. Click once with the middle mouse button to fit to window. Fig. 4.3

Parameters to describe a drawbead Lock bead A lock bead is defined with the following parameters (Fig. 4.4): • • • • •

Radius R: Draw in radius Height h: Height of lock bead Radius r: Radii of lock bead Clearance c: Clearance Width b: Width of lock bead


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Lesson 4: Drawbead generator The parameters can be changed graphically by moving the dashed lines (Fig. 4.4) or directly with the input fields for the parameters. Fig. 4.4

Parameters to describe a lock bead Lock Step A lock step is defined with the following parameters (Fig. 4.5): • • • •

Radius R: Draw in radius Height h: Height of lock step Radius r: Radius of lock step Clearance c: Clearance

Fig. 4.5

Parameters to describe a lock step The parameters can be changed graphically by moving the dashed lines (Fig. 4.5) or directly with the input fields for the parameters. www.forum.alghaform.com

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Lesson 4: Drawbead generator

Forces The middle part of the Drawbead generator window shows results of the calculation of restraining forces and hold down force (Fig. 4.6) and the diagram allows the user to determine the profile geometry of the bead for a given restraining force. Fig. 4.6

Forces Under the Result option, the user can decide whether the Force factor (forces with respect to yield stress and thickness) or the Line force (forces in N/mm for a 1 mm line) is to be calculated. These calculated forces (Restraining force and Hold down force) are shown below. The drawbead graphics window shows calculated forces based on the specified geometric parameters (R, h, r, c and B). The vertical line can be moved (with right or left mouse button) and the calculated forces are updated immediately. Depending on the specified geometric parameter, (e.g. r) the geometry of the drawbead profile also changes. With this option the user can find the geometry profile of the drawbead for a given force (e.g. a result of an optimization run).

Parameters for process In the lower part of the Drawbead generator, parameters for the process can be specified which influence the calculated forces (Fig. 4.7).


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Lesson 4: Drawbead generator Necessary inputs are for • • • • •

Sheet Thickness Friction Forming Velocity Material One drawbead or outer drawbead (single) or inner drawbeads (double)

Fig. 4.7

Inputs for process parameters If double drawbead are used, the button named double is used to specify the inner drawbead of these two. The outer drawbead can be specified by selecting outer DB:. If one of the process inputs in the Drawbead generator window is changed, the forces are recalculated. More drawbeads can be created with the Add button while the Delete button (Fig. 4.1) removes existing drawbead geometries.

Working with Drawbead generator The following parameters from Drawbead generator have to be used Drwbds page of the Input generator: Drawbead generator

Input generator

Shape

Width w

Width

Forces

Restraining, if Force factor button is active

Forcefactor

Since the Drawbead generator is currently a Beta–Version, the calculated values for Width and Restraining have to be input manually in the Input generator. This will be done automatically in the next version.


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Lesson 5: Tipping and Cutting

2. 5 Lesson 5: Tipping and Cutting This lesson describes tipping and cutting operations in AutoForm. Fig. 5.1

Tool geometry of Lesson 5 with cutting lines The drawing direction in AutoForm is always z–direction. The geometry must be always checked for undercuts. If undercuts exist, the geometry has to be tipped (using the Tip page) to find a good drawing direction.

Preparation of Simulation Open a new simulation: File > New ... > File name: in_lesson_05 > OK Geometry generator window is opened File > Import ... > af > OK > in_lesson_05.af > OK Drawing direction is modified from Tip page (Fig. 5.2).


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Lesson 5: Tipping and Cutting Fig. 5.2

Tip page of Geometry generator

Total Tipping

• Double attached: Various options to tip double attached parts • Define...: Definition of a new center of rotation for tipping the part • Average Normal: Uses normal vector of geometry as drawing direction. • Min draw depth: Calculates a drawing direction with minimum drawing depth. • Min backdraft: Calculates a drawing direction with minimum undercuts. • Screen axes: Uses the normal of the display as drawing direction. www.forum.alghaform.com

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Lesson 5: Tipping and Cutting • Set draw dir ...: Definition of drawing direction with two points or one line • Reference ...: The drawing direction of the active tool is adapted to the drawing direction of a selected reference tool (e.g. helpful for multistage process, to adapt the drawing direction of the different stages). • Sync: Mirrors drawing direction for double attached parts. • Reset: Uses the original axis of CAD data (z–axis) as drawing direction. • Import ...: Reads in a rotation matrix. • Export ...: Write out a rotation matrix in VDAFS–, IGES– or AutoForm–format. • Incremental tipping: Allows rotation by a specific angle around x–, y– or z–axis or around a user defined axis. • by degrees: Specific angle • by dx dy dz: distance in x–,y– and z–direction, to move the geometry. • rotate +/-: Start rotation. • move +/-: Start displacement. • Backdraft diagram: All possible undercut–free drawing directions are calculated (using Plot) and displayed in the diagram. If the center of the plot is completely within the green circle the geometry is undercut free (default: Safe > 3°); if the center is between green and red circles, geometry is in marginal area (default: Marginal: 0° ~ 3°); if the center is outside the red circle, geometry has undercuts (default: Severe: ≤ 0°). This diagram helps to find an undercut free drawing direction: • X-/Y-/Z-Axis: Shows the rotation matrix of the part. • Current transformation: Real transformation (rotation around x–,y– and z–axis and displacement at x–,y– and z– direction)


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Lesson 5: Tipping and Cutting Display > Backdrafts (Fig. 5.3). Fig. 5.3

Tool geometry of Lesson 5 with undercuts Display menu of Geometry generator with Backdrafts switched on To find a good drawing direction it is recommended to use the option Average normal and then rotate manually until an undercut free drawing direction is found. In this example we use the option named Min backdraft. Here the geometry is rotated about the z–axis by +65 degrees to align the geometry with the x–axis. The current rotation (Tip page bottom) should read X = -71.58, Y = 50.66, Z = 65 degree.

Fig. 5.4


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Tipped geometry Definition of tools Select faces of binder surface (right mouse button or Shift – right mouse button for selecting multiple faces)

Prepare

Define objects: Binder

Input generation Model > Input generator ... > Simulation type: Incremental > OK The title is already pre–defined. On Tools page Columns have to be defined for the binder. It is recommended to use Tool center Complete input using tabs from left to right. Since it is a single action process, use the following position values for the tools: Tools > punch > Move: 0 > binder > Move: 30 Columns > None > die >Move: -530


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Position of tools Blank

The blank is first created in CAD and imported to AutoForm: Blank > Import ... > af > Use all > Rotate > OK (Fig. 5.7)

Fig. 5.7

Dialog: Import line(s) Select a file > In_lesson_05_crv.af > OK File named in_lesson_05_crv.af contains all curves which are used in this lesson (cutting lines, cutting directions, blank). Select curve > Curve 1 > OK (Fig. 5.8).


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Dialog: Select curve with selected curve Curve 1 For a single action process, the blank has to be positioned on the binder. Position > On: binder

Blank

Add a drawbead with a force factor of 0.35: Add > Drawbead … > Use default settings > Add drawbead Drwbds > Tools > Above: die > Below: binder Drawbead line > Copy From … > Bndry (Pre) 1 > OK Drawbead line > Edit … > Global mod > Expand: 20 > OK Width: 15 > Forcefactor: Medium 0.35 Drwbds page should look like fig. 5.9.


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Drwbds page The main display with punch and binder switched on should look like fig. 5.10 Fig. 5.10

Punch and binder with blank and drawbead www.forum.alghaform.com

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Lesson 5: Tipping and Cutting Complete single action process definition on the Process page: Gravity gravity > Gravity: Downwards > Tool control: Show all > die: Non-active punch: Stationary binder: Stationary (Fig. 5.11) Fig. 5.11

Input for gravity Binder wrap During binder wrap phase, the die moves towards the binder, and the binder and the punch are stationary. closing > Tool control: die > Displcmnt > Velocity: 1 > Set > punch: Stationary > binder: Stationary Duration > During time > Time: 500 (Fig. 5.12) www.forum.alghaform.com

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Input for binder wrap Drawing During the drawing phase, the die moves over the punch, the binder is force–controlled and is displaced by the die, while the punch is stationary. drawing > Tool control: die > Displcmnt > Velocity: 1 > Set > punch: Stationary > binder > Force > Relative tool: > die > Const pressure > Value: 3 > Set Duration > During time > Time: 30 (Fig. 5.13)


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Input for drawing

Definition of different cutting process types The definition of cutting processes is always done on Process page of the Input generator. In AutoForm different cutting types can be defined: • Relief cut • Trimming cut • Hole

Definition of a relief cut 5 mm before bottom down The following steps have to be defined: • Drawing process (existing process drawing) must be stopped 5mm before bottom down. • Cutting line for relief cut must be defined. • Drawing process must continue until bottom down. www.forum.alghaform.com

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Stop drawing process 5mm before bottom down Select process step drawing on Process page. Duration of drawing is 30. This value must be changed to stop the process 5mm before bottom down. drawing > Duration > During time > Time: 25 Change the name of this process step: drawing > Name: drawing1 (Fig. 5.14) Fig. 5.14

Drawing until 5mm before bottom down


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Definition of a relief cut A new process step has to be added to define a relief cut. Add process step ... > Cutting > Insert position: Insert after > drawing1 > Add process step On Process page a new subpage is created (Fig. 5.15), which must be completed: Fig. 5.15

Input for definition of relief cut Process step > Name: cutting1 > Cut 2D > Cut Contour: Copy from … > Select curve > Curve 4 > OK > Cutting type: Open cut


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Lesson 5: Tipping and Cutting The geometry (punch and binder switched on) should look like fig. 5.16. Fig. 5.16

Punch and binder with defined relief cut

Finishing deep drawing process (last 5 mm) Now the deep drawing process must be completed (last 5 mm). A new process step has to be added again: Add process step ... > Forming > Insert position: Insert after > cutting1 > Add process step (Fig. 5.17) Fig. 5.17

Add a new process step to finish deep drawing process Process step > Name: drawing2 > Type: drawing www.forum.alghaform.com

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Lesson 5: Tipping and Cutting Tool control: Tool movement remain unchanged. Duration > During time > Time: 5 (Fig. 5.18) Fig. 5.18

Input of process step to finish deep drawing process

Definition of trimming cut A new process step has to be added as last process step for the definition of a trimming cut. The cutline curve is taken from the file in_lesson_05_crv.af. Add process step ... > Cutting > Insert position > Insert after > drawing2 > Add process step Name: cutting2 > Cut 2D > Cut contour > Copy from ... > Select curve > select curve in main display (Curve 1) with right mouse button (Fig. 5.19) > Select curve > OK


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Cut line for trimming cut Cutting type > Trimming cut (Fig. 5.20) For Trimming cut all elements outside the cutline will be deleted. Fig. 5.20

Input for trimming cut www.forum.alghaform.com

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Definition of two holes with cutting direction not along z–axis Finally, two holes with different cutting directions should be defined. The cutting lines as well as the vectors to determine the cutting directions have already been imported from the file in_lesson_05_crv.af. New process steps have to be added: Add process step ... > Cutting > Insert position > Insert after > cutting2 > Add process step Process step > Name: cutting3 > Cut 2D > Copy from ... > Select curve > select curve in main display (Curve 2) with right mouse button (Fig. 5.21) > Select curve > OK Fig. 5.21

Defined cut line for first hole Cutting type > Hole For Hole all elements inside the cut line will be deleted. Use a line to define the cutting direction: cutting3 > Cutting direction > Copy f. … > Select curve > Curve 3 > OK (Fig. 5.22) > Keep


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Cutting direction for first hole


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Input for first hole Do the same for the definition of the second hole: Add process step ... > Cutting > Insert position > Insert after > cutting3 > Add process step Process step > Name: cutting4 > Cut 2D > Select curve > select curve in main display (Curve 3) with right mouse button (Fig. 5.24) > Select curve > OK


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Defined cut line for second hole Cutting type > Hole Cutting4 > Cutting direction > Copy f. … > Select curve > Curve 2 > OK > Replace > Keep (Fig. 5.25) Fig. 5.25

Cutting direction for second hole


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Input for second hole Input is completed. Start the Simulation Job > Start simulation ... > Start job > Program: af_3.1 > Start


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Lesson 6: Optimization

2. 6 Lesson 6: Optimization This lesson describes in a simple example how process parameters can be automatically optimized using AutoForm’s optimization algorithm. The process parameters can be binder forces or drawbead force factors. Fig. 6.1

Punch, binder and drawbeads of the optimization example AutoForm offers an optimization algorithm that is fully integrated into the user interface. It allows the user to optimize various input parameters, so that a robust and high–quality part can be produced consistently. Optimization criteria can be defined by the user by using the different FLD zones. In most cases, the criteria will be used to produce a part without any cracks/splits and wrinkles, and having a uniform thickness strain (e.g. 2%) in all areas. Input parameters, which are available for an optimization can be binder forces, drawbead force factors, blank size or tool geometry (using AutoForm–DieDesigner). For all these optimization parameters, the user defines (a) the parameters and (b) the allowable minimum and maximum values of these parameters. Selected optimization parameters are marked in the Input and Geometry generator in yellow (highlighted). Parameter studies are also possible with AutoForm–Optimizer. Input parameters can be automatically varied and the result variations can be analyzed to determine the process sensitivity and dependence on the parameters. The goal is to find the dependency of the results of the drawing process on the parameters and to determine a process window.


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Lesson 6: Optimization In the following example, an optimization is defined for the drawbead forces of three drawbeads for an incremental simulation (geometry from Lesson 5) of a single action press. Open simulation file in_lesson_06_basis.sim: File > Open > in_lesson_06_basis.sim > OK Create an optimization: Model > Input generator … > Create > Optimization First the design variables have to be defined, and these will then be varied automatically by the optimization algorithm to achieve better quality of the draw part. Drawbead Force factors of beads bead1, bead2 and bead3 will be optimized. This process is setup as follows: Drwbds > bead1 > Forcefactor Click with right mouse button on the yellow framed input field of the drawbead force factor. A menu titled Add/edit design variable is opened (Fig. 6.2). Fig. 6.2

Menu to define design variable


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Lesson 6: Optimization • Name: Name of design variable • Dependent: Name of a previously defined design variable: This defines a dependent design variable, which means the value of this parameter depends on the previous one. • Independent: Definition of a fully independent design variable • Start: Starting value of design variable to use • Min: Minimum allowable value of design variable • Max: Maximum allowable value of design variable The optimization range of all three drawbeads is between „no drawbead“ (Forcefactor = 0.0) and lock bead (Forcefactor = 2.0). The starting value for each drawbead is „no drawbead“ (Forcefactor = 0.0). All three drawbeads will have the same geometry. This means only one independent parameter needs to be used. The other two design variables will depend on the first one. This reduces calculation time for this example. In reality all three design variables would be treated as independent. Complete the input for the force factor of the first drawbead (design variable) in the menu Design variable definition of the menu Add/ edit design variable as follows: Name: db > Dependent: Independent > Start: 0 > Min: 0 > Max: 2 (Fig. 6.2) > OK Now the background color of input field has changed to yellow. This means the parameter is to be used as a design variable. The name of this variable is displayed in the input field (Fig. 6.3).


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Lesson 6: Optimization Fig. 6.3

Menu to define bead1 – Forcefactor is defined as db Repeat the same steps for bead2, which should be defined as being dependent on bead1 (design variable db). Use the following input: Input generator > Drwbds > bead2 > Forcefactor Name: db2 > Dependent: db > Min: 0 > Max: 2 (Fig. 6.2) > OK The input field Start: has no value, because it is a dependent design variable. The background color of this input field has changed to yellow. The name of the design variable is displayed in the input field (Fig. 6.4).


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Menu to define bead2 – Forcefactor is defined as db2 Repeat for bead3: Input generator > Drwbds > bead2 > Forcefactor Name: db3 > Dependent: db > Min: 0 > Max: 2 (see Fig. 6.2) > OK As seen above, the input field Start: has no value, because it is also a dependent design variable. The background color of this input field has changed to yellow. The name of this variable is displayed in the input field (Fig. 6.5).


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Menu to define bead3 – Forcefactor is defined as db3 All design variables have been defined now. Complete the input on Optimize–page in the Input generator. Switch to this page (Fig. 6.6).


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Optimize – Design v. page of Input generator Design variables

• Optimization/Parameter study: Definition of optimization or parameter study • Optimization: Optimization will be performed. • Normal random: Parameter study; variables will have a Gaussian distribution around a defined center in parameter range. • Uniform random: Parameter study; variables will have an arbitrary distribution in parameter range. • Regular grid: Parameter study; variables will have a regular distribution in parameter range with a specified number of calculations. • Name: Name of design variable • Current: Current value of design variable for the opened simulation file • Start: Start value of design variable • Min: Minimum value of design variable • Max: Maximum value of design variable www.forum.alghaform.com

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Lesson 6: Optimization Switch to sub page Optimize – Control (Fig. 6.7): Fig. 6.7

Optimize – Control page of the Input generator • Maximum number of simulations: Maximum number of simulations for an optimization or parameter study. The study will be stopped if the maximum number of iterations is reached. • Accuracy: If variation of target function is smaller than the Accuracy value. Optimization/parameter study will be stopped (convergence has been reached).

Iteration control

• All: All simulations are stored on disk (warning: this requires a large amount of disk space). • Series of best: The next best simulation is always stored on disk. • Only best: Only the best simulation is stored on disk. • None: No simulation is stored on disk.

Keep simulations


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Lesson 6: Optimization Hosts

User can specify a list of computers which can be used for optimization/parameter study: • Name: Name of computer • Directory: Directory in which simulations can be stored temporarily. • #Lic: Number of AutoForm Licenses on computer • #Jobs: Number of jobs, which can run in parallel • Use: Use or do not use this computer for this optimization/ parameter study. • Add host …: Specify a new computer for optimization/ parameter study. • Edit host …: Edit computer parameters for optimization/ parameter study. • Save hosts: Save specified parameters of computers. No inputs are necessary on Control–page for this example. By default, the local computer is selected and activated for usage for optimization/parameter study. The directory in which simulations are stored is the directory from which the AutoForm user–interface was launched or from which the simulation file was opened. Click on the host name on Control page. Now open the menu named Add/edit hosts by clicking the button Edit host ... (Fig. 6.8):

Fig. 6.8

Add/edit host host–menu on Control page of optimizer


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Lesson 6: Optimization • Hostname: Name of computers • Get possible executables from host: Search for available AutoForm solvers. Solvers are displayed in the Incremental and Onestep fields. • Working directory: Directory in which the simulation file is stored. • Remote shell: Type of shell • Remote copy: Remote copy command • Names of executables: Names of AutoForm solvers • Incremental: AutoForm–Incremental solver • # Incremental licenses: Number of AutoForm–Incremental solver licenses • Onestep: AutoForm–Onestep solver • # Onestep licenses: Number of AutoForm–Onestep solver licenses • OK: OK • Cancel: Cancel

Host definition

Close this menu using Cancel. Switch to the Target page (Fig. 6.9). The target function is defined for two regions: • No cracks are allowed for the whole part. • A minimum thinning of 2% is requested for the punch area. • These two areas (whole part – Target and punch – Target1) are defined in AutoForm by default. Only the following inputs have to be changed on pages Target and Target1 of the Optimize page in Input generator: Target > Global target function > Cracks > Limit % FLC: -20 All other target values (Excessive thinning, Wrinkles, Insuff. Stretching, Desired strain) should be deactivated (Fig. 6.9).


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Target page of Optimizer • Cracks – Limit % FLC: Target area – Percentage above (+) or below (-) the FLD • Excessive thinning – Acceptable thinning: Maximum acceptable thinning • Wrinkles – Acceptable thickening: Maximum acceptable thickening for wrinkles • Insuff. Stretching – Required thinning: Required thinning • Desired strain – Desired major=minor strain: Desired plastic strain Target1 > Local target function > Cracks > Limit % FLC: -20 > Insuff. stretching > Required thinning: 0.02 All other target values (Excessive thinning, Wrinkles, Desired strain) should be deactivated (Fig. 6.10).

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Target1 page of optimizer Save the optimization input in file in_lesson_06.opt using the following options: File > Save as … > in_lesson_06.opt > OK Start the optimization using: Run > Start Optimization … > Program: afopt_3.1 > Start (Fig. 6.11)


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Optimization manager page File

• Save as plain simulation …: Save as simulation without optimization. • Fork to new optimization ...: Save as a base simulation file for new optimization. • Delete simulations …: Delete the stored simulation files (user–selected). • Strip optimization: Delete all simulation files except base simulation file.

Buttons

• Program: Choice of optimizer version • Start: Start optimization • Open sim.: Opens a stored simulation file from an optimization run. • Base: Choice of stored simulation files from an optimization run • Convergence …: Display of convergence of the optimization run. • Delete sim …: Delete stored simulation files (user– selected). • Dismiss: Close the Optimization manager menu


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Lesson 6: Optimization

Analyze optimization results When all simulations of the optimization run have been completed, open the simulation file using: File > Open optimization ... > in_lesson_06.opt > OK First open the menu titled Start/manage optimization ... using: Run > Start/manage optimization ... (Fig. 6.12) Fig. 6.12

Optimization manager page is opened when optimization run is finished Use the Convergence ... menu to get a first overview about the number of simulations, behavior of convergence, and the best simulation result. Open the Convergence ... menu using: Run > Start/manage optimization ... > Convergence ... The target function value is displayed over the number of simulations (Fig. 6.13).


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Menu Convergence with activated option Target Stored simulations are marked with a bullet, and the best simulation (31st) with a rectangle. Switch to option All criteria (Fig. 6.14). The target function is now divided into single criteria, displayed over the number of simulations in the optimization run. The different criteria of the target function are: • Wrinkles/Insufficient stretching • Desired strain • Cracks/Excessive thinning It can be seen that cracks are the reason for peaks in the target function (Fig. 6.14).


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Menu Convergence with activated option All criteria Switch to the option Log(Target) (Fig. 6.15). The target function value is now displayed in logarithmic form over the number of simulations in the optimization run. Fig. 6.15

Menu Convergence with activated option Log(target)


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Lesson 6: Optimization Open the first simulation of optimization using: Run > Start/manage optimization ... > Open sim.: 1 > Yes (Fig. 6.16) Fig. 6.16

Optimization manager page with simulation 1 open Use Ctrl – E to go to the simulation end and switch on the Formability result variable. It can be seen that insufficient stretching occurs in large areas of the part. Switch on the display of all lines in AutoForm’s main menu area: Display > Lines ... > Lines: Show all > Dismiss or use hotkey Ctrl – L to open Lines menu. Click with the right mouse button on the three drawbeads (design– variables) which should be optimized to get the current force factors (Fig. 6.17).

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Simulation 1 of optimization run with result variable Formability and drawbeads with force factors Now open the best (# 31) simulation of the optimization run using: Run > Start/manage optimization ... > Open sim.: 31 > Yes (Fig. 6.18) Fig. 6.18

Optimization manager page with simulation 31 open


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Lesson 6: Optimization Use Ctrl – E to go to the end of the simulation and switch on the Formability result variable. It can be seen that the part is much more uniformly stretched. Switch on the display of all lines: Display > Lines ... > Lines: Show all > Dismiss or use hotkey Ctrl – L to open Lines Click with the right mouse button on the three drawbeads which should be optimized to get the current force factors (Fig. 6.19). Fig. 6.19

Simulation 31 of optimization run with result variable Formability and drawbeads with force factors



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Lesson 7: Automatic Filleting with a Constant Radius

2. 7 Lesson 7: Automatic Filleting with a Constant Radius The functions described in this lesson are used in the preparation of the simulation data. At the beginning of each simulation the geometry of the meshed CAD tool data should be checked for sharp edges. In case there are any sharp edges AutoForm– Incremental can automatically fillet these with a global radius. Warning: Warning Sharp edges that are not filleted during the preparation of a simulation may lead to faulty results (unrealistic cracks).

Global filleting of sharp edges The procedure of checking and filleting are presented through following simple example. (Fig. 7.1). Fig. 7.1

Geometry First the geometry in VDAFS format is read in and meshed: File > New ... > in_lesson_07 > OK www.forum.alghaform.com

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Lesson 7: Automatic Filleting with a Constant Radius File > Import ... > VDAFS > OK > in_lesson_07.vda > OK > Program: afmesh_3.1 > OK Checking of sharp edges and filleting if necessary is done in the geometry editor on the Fillet page (Fig. 7.2). Fig. 7.2

Fillet page in the Geometry generator • Check: Checks geometry with the Check radius (e.g. 2 mm). • OK: Accepts the result. • Global radius: Value of the global filleting radius (default value: 3 mm). This button becomes active only after pressing OK. • Apply: Fillets all edges with the Global radius value. • Filleted geometry: Displays filleted geometry (Fig. 7.3). • Edged geometry: Displays edged geometry with the located sharp edges (Fig. 7.4). All of the above mentioned buttons will become active only after selecting Apply. www.forum.alghaform.com

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Lesson 7: Automatic Filleting with a Constant Radius Fig. 7.3

Filleted geometry (Partial view) Fig. 7.4

Edged geometry with the located sharp edges (Partial view) In combination with AutoForm DieDesigner there is an additional function to create local fillets on selected edges of the meshed part geometry. This can be either done with a constant or a variable radius. www.forum.alghaform.com

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Lesson 7: Automatic Filleting with a Constant Radius After using the Fillet function in AutoForm the preparation of the simulation continues as already described in the previous lessons. Opening the Input Generator AutoForm automatically uses the filleted geometry of the tools.

Use of the filleted or edged geometry As already described the Input Generator automatically takes the filleted geometry of the die, punch and binder. However, AutoForm retains the original edged geometry in memory. It is possible to toggle between the edged and the filleted geometry at any time. This can be done on the Tools page in the Input Generator. Go to Tools page: Geometry > Reference.... The window titled Reference tool geometry will be opened. Using Options (Fig. 7.5) you can choose between the edged and the filleted geometry: • edged: Use original faces • filleted: Use processed faces (Fig. 7.5). Fig. 7.5

Window: Reference tool geometry In this window you may choose whether the edged or the filleted geometry should be used for the definition of tools.


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Lesson 7: Automatic Filleting with a Constant Radius

Definition of tools with automatically filleted die radius In case sharp edges between the binder and addendum are found and automatically filleted, this area is treated by AutoForm Incremental in a special way. During the automatic filleting in AutoForm Incremental a radius is generated at both adjoining faces. The binder receives half of the fillet radius and therefore that the binder surface is modified (see Fig. 7.6 red elements, binder is no longer flat). Fig. 7.6

Faces after automatic filleting In order to avoid this problem, the following procedure should be followed: • • • •

Load the tool geometry, define binder surface, check for sharp edges and fillet. AutoForm then generates the die and punch using the filleted geometry and the binder using the edged geometry

These steps are described in detail in the following sections. For this purpose, the example in_lesson_07.vda is used, which should www.forum.alghaform.com

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Lesson 7: Automatic Filleting with a Constant Radius already have been imported and meshed. Starting from this point the preparation steps of the simulation will be described. Define binder By defining the binder surface the tool geometry is divided automatically in die, punch, and binder. The corresponding faces can be selected on the main using Shift and the right mouse button (Fig. 7.7). Fig. 7.7

Selected faces describing the binder Prepare

Define objects: Binder Check geometry for sharp edges and automatic filleting Change to the Fillet page in the Geometry generator and check the geometry for sharp edges (Check radius value = 2 mm).

Fillet

Check radius: 2.00 > Check > OK Some sharp edges have been found. They are shown in Fig. 7.4 in blue. Now, fillet these sharp edges with a global radius of 12 mm. www.forum.alghaform.com

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Lesson 7: Automatic Filleting with a Constant Radius Global radius: 12.00 > Apply The resulting filleted geometry is shown in Fig. 7.3. Open the Input generator. In Fig. 7.8 you can see the tools, which have been defined automatically. Fig. 7.8

New tool geometries (die and punch with filleted edges, binder with sharp edges) Completing the Input generator The Input generator still has to be completed in this example in the same way as in the previous lessons: The positioning of the tools should be changed to a single action process:

Tools

die > Move: -600 punch > Move: 0 binder > Move: 100 binder > Columns: Tool center Here the blank is defined as an arc segment. This is carried out with the following commands:

Blank


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Lesson 7: Automatic Filleting with a Constant Radius Outline > Arc ... > Center x, y: 0, 0 > Radius: 270 > Angles > Start: 0 > End: 90 > OK (Fig. 7.9) Fig. 7.9

Definition of the blank as a circular segment The fields Center and Radius define center and radius of the circle. To define a circular blank this information is sufficient. In this example the tools are symmetrical, therefore only one quarter of the circular blank is required. The first quarter of the defined circle is used. This is defined with the values Start 0 and End 90. In addition, the symmetry planes for the blank have to be defined. This is carried out in the lower half of the Blank page: Add symmetry ... > Symmetry-plane at start side > OK (Fig. 7.10) Add symmetry ... > Symmetry-plane at end side > OK Fig. 7.10

Window for definition of the symmetry planes if the blank is a segment of a circle Due to the definition of the blank as a segment instead of being defined by nodes, the symmetry plane cannot be chosen by clicking on one side of the blank as shown in previous examples. In these cases the start and/or end side can be defined as the symmetry plane (see Fig. 7.10).


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Lesson 7: Automatic Filleting with a Constant Radius An additional input which has to be provided, is the initial location of the blank. On the Tool page the single action process was already taken into consideration. This means that the blank is positioned on the binder. This has to be defined on the Blank page. As a default the blank is placed on the die (see Blank page> Position > On: die). This button has to be changed to binder (Fig. 7.11). Fig. 7.11

Detail Blank page: At the beginning of the forming process the blank lies on the binder On this page the process is defined. In this example, the punch is located on the press bed, and during the forming process the die moves and pushes the binder downwards. The following tool movements explain every single process step:

Process

gravity > Downwards die: Non-active punch: Stationary binder: Stationary closing > Type: Binder wrap Tool control > Show all die > Displcmnt > Velocity: 1 > Set punch: Stationary binder: Stationary Duration > During time > Time: 500 drawing > Type: Drawing die: Displcmnt > Velocity: 1 > Set punch: Stationary binder: Force > Relative tool: die > Const pressure > Value: 3 > Set Duration > During time > Time: 100 In the lower half of the Control page there is the WriteRestart button. This button selects whether an additional Restart file (*.rst) should be generated during simulation. This file contains all infor-

Control


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Lesson 7: Automatic Filleting with a Constant Radius mation necessary to later continue the simulation in a separate example. For this case the button WriteRestart should be activated. WriteRestart > On Advanced … > RestartTimeStep: Auto (Fig. 7.12) Fig. 7.12

Window to define Restart Time Steps Next to this button, there is another button called Advanced …. Clicking the Advanced ... button opens a window (Fig. 7.12), where you can define the intervals of the information written to the Restart File (RestartTimeStep). If Auto is selected (see Fig. 7.12) information at the end of each process step is written to the restart file (end of gravity, binder wrap and drawing). This means that the new simulation can only be re–started at the end of one of those process steps. If a different value is given (e.g. 10) the information is saved to the restart file after ever 10 time steps. If for example one process step such as drawing takes 100 seconds (see Process page > Duration) the information is written to the Restart file a total of 10 times. This causes the size of the Restart file to be substantially larger and the calculation takes longer (as writing the Restart file takes more time). However a new simulation could be re–started at any 10 second interval. The appropriate settings have to be estimated by the user. Start of the Simulation Job > Start simulation ... > Kinematic check only > Start With kinematic check the tool movement can be controlled. If everything is defined correctly the simulation can be carried out without this option (Kinematic check only – off).


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Lesson 8: Multiple Step Process and Starting from Restart File

2. 8 Lesson 8: Multiple Step Process and Starting from Restart File AutoForm–Incremental allows simulation of deep drawing processes that consist of several process steps (e.g. multi–stage processing). CAD data is required for every process step and each set of tools. The preparation of such Input will be explained using the example from Lesson 7 (Automatic filleting with a constant radius and starting of a simulation with the Restart file). The part is drawn in two drawing steps (Fig. 8.1). Fig. 8.1

Example in_lesson_08 In this case there are two possible approaches: • Either the entire process (i.e., both steps) is defined in a single simulation file. In comparison to a standard simulation, the tools (die, punch, binder, etc.) for both drawing steps and for the complete process have to be defined. As a result, the AutoForm simulation file contains result from both drawing steps. • Or the first drawing process is simulated (when, for example, only the tools for the first drawing step are available). In this case, during the simulation, a restart file can be generated. In this Restart File all necessary information is saved in order to continue the drawing process using a separate simulation. This means the second step will be carried out at the end of the first drawing operation as a separate simulation.


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Starting a simulation using a Restart File In Lesson 7, the WriteRestart button in the Input generator on the Control page was activated. This implies that during the calculation of this example, a restart file (*.rst) has been generated. In the following, the second drawing process step will be prepared for a separate simulation. As the first step, the results of Lesson 7 have to be read in. There are two ways of doing this: • Open *.sim file or • Open *.rst file. Proceed as follows. Open the *.sim file: File > Open ... > in_lesson_07.sim > OK The information from both files in_lesson_07.sim and in_lesson_07.rst are loaded. Therefore, the results of the first drawing step can be viewed while preparing the new simulation for the second step. After opening the sim files the results of the first drawing step are shown. In order to define the input for the second drawing step, the Input generator should be opened with the command: Model > Input generator ... Open the *.rst File: File > Open restart ... > in_lesson_07.rst > OK Only the information from file in_lesson_07.rst is loaded into the Input generator. The results are not visible. In this case, the Input generator opens automatically. No results are seen on the main screen. The Input generator After opening both files, all information about the first drawing step are available in the Input generator, independently from opening either the *.sim or *.rst files. In contrast to a standard simulation the Title page has also been changed (Fig. 8.2).


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Lesson 8: Multiple Step Process and Starting from Restart File Fig. 8.2

Title page in the Input generator after opening a *.rst file The upper half of the Title page is as before. In the lower half, there is the necessary information to define a subsequent simulation in a separate calculation. • Job info: Contains general information about the first simulation (date, user, hostname, jobname, directory). • Restart times: These are all process steps and time steps written to the *.rst file. In Lesson 7, the end of each process step was saved to the restart file. Hence in Fig. 8.2 it can be seen that time steps 0, 500, and 600 are shown corresponding to the process steps gravity, closing and drawing. Thus a new simulation can be created after each time step. For this the button Make restart (next to the desired time step) has to be clicked. All the restart options for this example will be explained below. After this, you may continue with the section titled Start of the current example from sim file. www.forum.alghaform.com

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Lesson 8: Multiple Step Process and Starting from Restart File Make restart after gravity process step If you wish to define a new simulation and just use the previous gravity results, press the button Make restart Make restart after the process step gravity Now a new *.sim File named in_lesson_07_r1.sim will be created. In addition a new subpage (Rst1) opens. You can switch between both subpages (Rst1 and Base) on the Title page (Fig. 8.3). Fig. 8.3

Detail of the Title page after pressing the Make restart button – switching between both Input generators is possible In the new Input generator all information used in the gravity process step are grayed out (cannot be changed) (Fig. 8.4 – 8.8). Fig. 8.4

Detail Tool page for the new simulation, only the die can be modified.


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Blank page of the new simulation – the blank cannot be modified Fig. 8.6

Lube page of the new simulation


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Lesson 8: Multiple Step Process and Starting from Restart File The friction can only be modified with respect to the die. If a Constant friction had been selected instead of Table, friction cannot be modified. Fig. 8.7

Detail of the Process page for the new simulation – process steps closing and drawing can be changed. Fig. 8.8

Detail of the Control page of the new simulation – both Binder wrap and Bending effects cannot be modified any more. Saving of data File > Save In case you would like to define another simulation for a different time step you have to read in the base simulation in_lesson_07.sim or in_lesson_07.rst.


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Make restart after closing If you wish to define a new simulation using only the previous results of gravity and binder wrap press the button titled Make restart after the process step closing. Note: Note A new *.sim file is created named in_lesson_07_r1.sim. in_lesson_07_r1.sim You have to rename this file before in order to avoid overwriting the previous restart file. In addition to the sim file, new input will also be generated. Again, it is possible to change only those values that have not been used previously in the gravity and closing process steps. • • • •

Tools: None of the tools can be changed. Blank: Blank cannot be modified. Lube: The friction cannot be modified for any of the tools. Process: The Duration of the process step closing can be changed, as this process step can be continued if desired. Also the process step drawing can be modified. • Control: Binder wrap and Bending effects cannot be changed any more. In addition to these allowable changes, new tools and process steps can be defined. This will be treated later in this lesson. Make restart after the process step drawing If you wish to define a new simulation using the previous results of the first drawing step press the button titled Make restart after the process step drawing. Note: Note A new *.sim file is generated named in_lesson_07_r1.sim. in_lesson_07_r1.sim You have to rename the file before in order to avoid overwriting the previous restart file. Again, it is possible to change only those values that have not been used in any of the previous process steps. • • • •

Tools: None of the tools can be changed. Blank: Blank cannot be modified. Lube: The friction cannot be modified for any of the tools. Process: The Duration of the process step drawing can be changed, as this process step can be continued if desired. www.forum.alghaform.com

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Lesson 8: Multiple Step Process and Starting from Restart File • Control: Binder wrap and Bending effects cannot be changed any more. Apart from the allowed changes new tools and process steps can be defined. This will be treated later in this lesson. On the lower part of the Title page there is an additional button: Recalculate all (see Fig. 8.2). This button is used if several simulation from the restart have been carried out. In order to create a single simulation file of all calculations – e.g. for better organization of the results file. With this button the complete simulation can be recalculated. Start of the current example from the sim file Open the simulation file from Lesson 7: File > Open … > in_lesson_07.sim > OK Model > Input generator … After the process step drawing > Make restart File > Save as ... > in_lesson_08.sim > OK Now a new Input generator is opened. In the following the second drawing step for this forming operation has to be defined. Tools and process are defined as in the previous lessons.

Definition of a multiple step process

Preparation of tool geometries for the second drawing step The CAD data with the corresponding tool geometry for the second drawing step has to be loaded, checked and divided into die, punch and binder. Model > Geometry generator > File > Import ... > VDAFS > OK > in_lesson_08_2.vda > OK > Program: afmesh_3.1 > OK Now the geometry has to be checked for • free boundaries, • sharp edges and • undercuts. Prepare

Apply www.forum.alghaform.com

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Lesson 8: Multiple Step Process and Starting from Restart File As there is only a single free boundary, the outline is automatically defined. (Fig. 8.9). Fig. 8.9

Determination of free boundaries Check for sharp edges Check radius: 2.00 > Check > OK

Fillet

No sharp edges have been found (Fig. 8.10).


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Checks for sharp edges Check geometry for undercuts: Tip > geometry is green (Fig. 8.11) which means there are no undercuts


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Geometry has no undercuts In the next step the geometry has to be divided into die, punch and binder. Select faces of the binder surface (right mouse button – Shift key) (Fig. 8.12). Fig. 8.12

Selected faces describe the binder for the second drawing step www.forum.alghaform.com

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Lesson 8: Multiple Step Process and Starting from Restart File Prepare > Define objects: Binder > Apply Preparation of the simulation Open Input generator: Model > Input generator ... There is already a title predefined (in_lesson_07). Change this to in_lesson_08. Definition of tools

On the Tools page die, punch and binder of the first drawing step are already defined. Those are grayed out and cannot be modified. For the second drawing step, the imported and separated tools have to be introduced. Therefore new windows have to be defined on the tools page. First, the die for the second drawing step will be defined. Add tool ... > Use settings of tool: punch (first the die has to be defined for the second drawing step, the punch is taken as reference) > Add tool (Fig. 8.13)

Fig. 8.13

Dialog to introduce a new window on the Tools page for die2 The orientation and working direction of the tools are different in the two drawing steps. In the first drawing step the forming was done in a single action process (see Lesson 2). That means that the die and the binder move towards the punch. The punch stays on the press bed. In the second drawing step the forming should be defined as a double–action process. The die is fixed to the press bed. Punch and binder are movable (see Lesson 1). As the specifications are to be done for the second drawing step (die2) it might be reasonable to take all defined values from the punch (drawing direction, etc.). This can be done in the dialog Add tool ... with the option Use settings of tool: punch (Fig. 8.13).

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Lesson 8: Multiple Step Process and Starting from Restart File By doing this, a new subpage appears on the Tools page. All entries for the tool have already been completed correctly. Only the name and geometry have to be defined. Name: die2 Geometry > Reference ... > Current geometry: 3 in_lesson_08_2 > Select objects > Part > Binder > OK (Fig. 8.14) Fig. 8.14

Window to define geometry of die2 During the preparation of the tool for the second drawing step, the imported geometry had already been divided into die, punch and binder. This division is now used for the definition of die2 as well (Select objects > Part > Binder in Fig. 8.14). The following is the entry for tool die2 in the Input generator (Fig. 8.15).


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Input for die2 Now the punch for the second drawing step has to be defined. The procedure for this has to be the same as before. As a reference we take the die from the first drawing step (die) and for the definition of the geometry just select the part. Add tool ... > Use settings of tool: die > Add tool (Fig. 8.16) Fig. 8.16

Dialog for the insertion of a new window on the Tools page for punch2 www.forum.alghaform.com

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Lesson 8: Multiple Step Process and Starting from Restart File Name: punch2 Geometry > Reference ... > Current geometry: 3 in_lesson_08_2 > Select objects > Part > OK The initial position of the punch must be entered also (punch2). This differs from the entries of the reference tool (die). The new definition is be done with the command: Working direction > Move: -100 (Fig. 8.17) For punch2, this results the following input (Fig. 8.17). Fig. 8.17

Tools page – Input for punch2 Finally the binder for the second drawing step has to be defined. As a reference we use punch2, as all entries for punch2 and binder2, (except the name and geometry) should match. When defining the geometry only the binder has to be selected. www.forum.alghaform.com

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Lesson 8: Multiple Step Process and Starting from Restart File Add tool ... > Use settings of tool: punch2 > Add tool Tools

Name: binder2 Geometry > Reference ... > Current geometry: 3 in_lesson_08_2 > Select objects > Binder > OK The following is the entry for tool binder2 in the Input generator (Fig. 8.18).

Fig. 8.18

Tools page – Input for binder2 Now a total of six tools have been defined in the Input generator (see Fig. 8.1 – for better illustration the tool of the second drawing step has been moved in the x–direction): The tools for the first step are die, punch and binder (taken from Lesson 7) and for the second drawing step are die2, punch2 and binder2.


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Lesson 8: Multiple Step Process and Starting from Restart File The blank has already been defined for the first drawing step in Lesson 7. The calculation continues with the partially finished part. No new entries are necessary.

Definition of the Blank

Friction can only be defined for the tools of the second drawing step (Fig. 8.19).

Friction (Lube) Fig. 8.19

Definition of the friction coefficient for the tools in the second step On the Process page all steps except drawing are grayed out. It is possible only to modify this page. We define the process (of the tool movement) for the second step instead. In the second step the following processes appear:

Process

• Positioning – the part is positioned on a tool for the second process step. • closing2 – closing of the binder for the second process step • drawing2 – second drawing step www.forum.alghaform.com

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Lesson 8: Multiple Step Process and Starting from Restart File Positioning of the part

In order to position the partially finished part on the tool of the second drawing step, a new step has to be introduced in the Input. Add process step ... > Positioning > Insert position: Insert after > drawing > Add process step (Fig. 8.20)

Fig. 8.20

Add process: process Dialog for positioning the partially completed part In the Input generator on the Process page, a new subpage is added. The name of the new process step is positioning1. This can be kept as is. This process step describes the transition between the first and the second drawing operation. It can be pictured as if the partially completed part (from the first step) would be taken by hand or by a robot arm out of the first tool set and put onto the second one. During the simulation, it is important not to leave out this process step as contact problems during the second step may arise. In this example, the partially completed part is positioned on die2, as this tool is mounted on the press table. Sheet positioning > On: die2 (Fig. 8.21)


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Detail Process page: Partially completed part is positioned on the second tool set Now comes the second process step. Binder wrap and drawing process are defined as separate process steps (as in reality and also in the previous lessons). Add process step ... > Forming > Use settings of forming step: > drawing > Insert position: Insert after > positioning1 > Add process step

Closing of binder

Name: closing2 (Fig. 8.22) Type: Restrike Tool control > Show all die: Non-active punch: Non-active binder: Non-active die2: Stationary punch2: Non-active binder2: Displcmnt > Velocity: 1 > Set Duration > During time > Time: 100

Process


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Process page: Input for the closing of the binder during the second forming operation Caution: Caution In defining the 2nd operation it is important to select Restrike as the drawing type (Fig. 8.22). Second operation

Add process step ... > Forming > Use settings of forming step: closing2 > Insert position: Insert after > closing2 > Add process step

Process

Name: drawing2 Type: Restrike Tool control > Show all die: Non-active punch: Non-active binder: Non-active die2: Stationary punch2: Displcmnt > Velocity: 1 > Set binder2: Force > Relative tool: die2 > Const pressure > Value: 20 > www.forum.alghaform.com

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Lesson 8: Multiple Step Process and Starting from Restart File Set Duration > During time > Time: 100 Fig. 8.23

Process page: Input for the 2nd drawing step Caution: Caution In defining the 2nd operation it is important to select Restrike as the drawing type (Fig. 8.23). WriteRestart > OFF

Control

Job > Start


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Lesson 9: Using CAM Tools

2. 9 Lesson 9: Using CAM Tools In the following lesson we will show an example where the working direction of the tool is not parallel to z–axis (Fig. 9.1). In these cases the following additional inputs have to be made: • Definition of working direction of CAM tools • Special parameters for process definition Fig. 9.1

Preparation of tool geometry Create a new simulation file: File > New ... > in_lesson_09 > OK Import and mesh tool geometry: File > Import > IGES > OK > in_lesson_09.igs > OK > Program: afmesh_3.1 > OK (Fig. 9.2)


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Lesson 9: Using CAM Tools Fig. 9.2

Imported geometry Check geometry for free boundaries: Prepare

Apply Free boundaries are displayed in blue color on the main display. Check geometry for sharp edges:

Fillet

Check radius: 2.00 > Check Message appears in log–window that no sharp edges have been found. Close window with the Dismiss command. Check geometry for undercuts: When activating the Tip page undercuts are immediately calculated for the active geometry and displayed in different colors on the main screen (Fig. 9.3).

Tip


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Result of checking geometry for undercuts Undercut areas in Fig. 9.3 are shown in red. The major part of the geometry is undercut free (green area). However, the area of the depression has undercuts (Fig. 9.4). For this geometry it is not possible to find a tipping position which has no undercuts. In this case a CAM tool has to be used. Fig. 9.4

Undercut area


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Lesson 9: Using CAM Tools As the last step, the geometry has to be divided into die, punch and binder. Prepare

Select faces of the binder (right mouse button or shift – right mouse button to select several faces, Fig. 9.5) Define objects: Binder Now the geometry is divided into die, punch, and binder. We have already generated the part boundary. Using the button Generate part boundary: Apply the generation of the part boundary starts and this boundary is displayed in blue.

Fig. 9.5

Selected binder face

Input generation for simulation Open Input generator: Model > Input generator ... > Simulation type: Incremental > Sheet thickness: 1 > Geometry refers to: punch side > OK On the Tools page, three tools have already been defined – die, punch and binder (Fig. 9.6).

Tools


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Automatically defined tools by AutoForm The positioning of the tool corresponds to a double action drawing process as the default in AutoForm. In this case we would like to define a single action process. Therefore the following changes have to be made: • The die is mounted on the ram: Move: -532 (Fig. 9.7) • The punch is mounted on the press bed: Move: 0 (Fig. 9.8) • The binder is positioned with respect to the punch (lifted): Move: 32 (Fig. 9.9) Fig. 9.7

Detail Tools page: Position of the die Fig. 9.8

Detail Tools page: Position of the punch


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Detail Tools page: Position of the binder On this page, the binder is still marked in red, as the columns have to be defined. It is recommended to use Tool center for this binder: Columns > Tool center Punch and binder can be used in this simulation as they are. From the die, the depression has to be removed and defined as a separate tool, i.e., the pad. die > Geometry > Reference ... > Current geometry > 1 in_lesson_09 > Pick faces > Select with the right mouse button and shift the faces of the depression (Fig. 9.10) > Deactivate > OK

Tools

Fig. 9.10

The selected faces describe the cam tool and are removed from the die In the next step, we can define the geometry for the cam. In order to do so, a new window has been added to the tools page (Fig. 9.11 lower left). Add tool ... > Use settings of tool: die > Add tool (Fig. 9.12)


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Add Tool... button Fig. 9.12

Window: Add Tool... Now the inputs in this new window have to be completed (Fig. 9.13):


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Tools page for the cam tool Name: cam As a reference for the cam tool the die had been used, therefore the positioning (above) and the offset (1) are already defined correctly. Geometry > Reference ... > Current geometry > 1 in_lesson_09 > Pick faces > Select with the right mouse button and shift the faces of the depression > Deactivate > Toggle active > OK (Fig. 9.14)


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Cam geometry Import and mesh of the curves from CAD file for the working direction The working direction of the cam tool is not parallel to the z–axis and has to be taken from the CAD file. This has to be done with the command: Model > Curve manager ... > File > Import ... > IGES > in_lesson_09_workdir.igs > OK > Program: afmesh_3.1 > OK (Fig. 9.15) On the main display: Ctrl – Y: to see geometry from Y–direction.


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Imports curve on the main screen Working direction > Copy f. ... > Select curve (The dialog opens automatically and all curves imported from the CAD file are displayed) > Curve 1 > OK > Replace A red arrow for the working direction appears in the main display (Fig. 9.16) and also the Question dialog window (Fig. 9.17), which confirms if this direction should be kept. Fig. 9.16

AutoForm suggested working direction for the CAM tool Fig. 9.17

Query if suggested working direction should be kept or reversed. Keep (the working direction with the suggested orientation is taken into the Input). Finally the CAM tool has to be positioned. Working direction > Move: -40 www.forum.alghaform.com

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Lesson 9: Using CAM Tools Now all entries for the Cam tool are defined. (Fig. 9.13) Blank

The outer boundary of the blank is defined in AutoForm. In the AutoForm user interface: punch and binder > display (Fig. 9.18) geometry > turn off (Fig. 9.18) Ctrl – Z: to show geometry from z–direction. Switch to show/hide geometry and tools On the Blank page of the Input generator: Outline > Copy from ... > Select curve > Bndry (Pre) 1 > OK

Fig. 9.18

Outline > Edit ... > Curve editor > Global mod > Expand: 25 > Convex: 20 > OK (Fig. 9.19) Position > On: binder

Fig. 9.19

The initial blank


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Lesson 9: Using CAM Tools Process

On this page the process is defined (movement of tools): Process step > Name: gravity > Downwards Tool control > punch and binder: Stationary

Gravity

Process step > Name: closing > Type: Binder wrap > Show all (small button on the right next to Tool control) Tool control > die > Displcmnt > Velocity: 1 punch and binder: Stationary cam: Non-active Duration > During time > Time: 500

Closing

Process step > Name: drawing > Type: Drawing Show all > Tool control > die > Displcmnt > Velocity: 1 punch > Stationary > Relative tool: die > binder > Force > Constant pressure > Value: 3 > Set > cam > Non-active > Duration > During time > Time: 32

Drawing

In the fourth process step, the CAM tool forms the depression. Since, by default, three process steps are defined, a new one has to be added:

CAM tool

Add process step … > (lower left) The dialog Add process step is opened (Fig. 9.20) Fig. 9.20

Dialog: Add process step ... After making all entries as in Fig. 9.20, select: www.forum.alghaform.com

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Lesson 9: Using CAM Tools Add process step … > (lower left) Process step > Name: cam > Type: Flanging Show all > Tool control > die > Force >Relative tool: punch > Constant pressure > Value: 3 > Set > punch: Stationary > binder: Stationary > cam > Displcmnt > Velocity: 1 Duration > During time > Time: 40 Attention: Attention This process step is of the type Flanging. Flanging This is necessary as the working direction is not parallel to the z–axis. Control – Input of numerical values WriteRestart > off Rslts > Contact distance above Rslts > Contact distance below Rslts > Curvature Start of Simulation Job > Start simulation ... > Kinematic check only > Start The movement of the tools can be checked with the kinematic check. If everything is defined correctly, the simulation can be started without a kinematic check. (Kinematic check only – off).


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Lesson 10: Use of Pad and Springback

2. 10 Lesson 10: Use of Pad and Springback In this lesson a process using a pad is described. At the end of the lesson, springback is calculated. Here, a pad means using an additional tool, which closes early with the punch and which is then displaced by the punch to avoid wrinkles. The geometry of the pad must be defined in these cases and new tool displacements must also be defined on the Process page. An U–shaped profile (Fig. 10.1) is used for this example. The geometry exists in IGES–format. Fig. 10.1

Example for use of a pad

Preparation of simulation Open a new simulation file: File > New ... > in_lesson_10 > OK File > Import ... > IGES > OK > in_lesson_10.igs > OK > Program: afmesh_3.1 > OK Check geometry for gaps Generate part boundary: Apply

Prepare www.forum.alghaform.com

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Lesson 10: Use of Pad and Springback Fillet

Check geometry for sharp edges Check radius: 2.00 > Check The message that (no) sharp edges have been found appears in log– window. Close with the Dismiss button.

Tip

Check the geometry for undercuts Use the Tip page to check the geometry for undercuts. The check is performed automatically; the results are shown in the main display. The geometry is free of undercuts.

Fig. 10.2

Result of check for undercuts

Generate tools die, binder and punch Prepare > Select faces of binder (right mouse button) Prepare > Define objects: Binder Now the selected patches are defined as the binder, unselected patches are defined as the punch and all the patches are defined as the die.


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Lesson 10: Use of Pad and Springback Fig. 10.3

Binder patches are selected

Generate simulation input Model > Input generator ... > Simulation type: Incremental The title is predefined but it can be changed. The three tools die, punch and binder have already been defined on Tools page.

Tools

Switch on display of all tools: Display > Tools ... > Show all > Dismiss


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Automatically defined tools by AutoForm Punch and binder can be used for the simulation. For the die, the upper patch must be deleted and defined as a separate tool, i.e., the pad. Switch to subpage named die on the Tools page, switch off display of tools and switch on display of meshed geometry. Now we can define geometry for the die: Geometry > Reference ... > Current geometry > 1 in_lesson_10 > Pick faces > Select the desired face with the right mouse button (Fig. 10.5) > Deactivate > OK


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Selected patch will be the pad geometry and it must be deleted from the die. Define geometry for the pad. Add a new tool on the Tools page. Add tool ... > Use settings of tool: die > Add tool Because the die was used as reference tool for the pad, only name and position have to be changed (Fig. 10.6). Tool name > Name: pad (Fig. 10.6) Geometry > Reference ... > Current geometry > 1 in_lesson_10 > Pick faces > Select the desired face with the right mouse button (Fig. 10.5) > Deactivate > Toggle active > OK


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Menu with input for the pad Now four tools have been defined, die, punch, binder and pad. The pad must be positioned by taking into account the position of the die, so that punch first closes with the pad and the sheet is clamped between these tools during the drawing process. Position of the pad can be changed using Move–option on the Tools page (Fig. 10.6). Move: 110 (positive direction, because the displacement should be in the tool working direction). Fig. 10.7 shows all tools in initial position.


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Defined tools in initial position Columns for the binder have to be defined. In this example we use: Columns > Blank center Blank

The blank outline is defined in AutoForm as follows: Outline > Input ...> Curve Editor > Create points with right mouse button > OK (Fig. 10.8) Corner points of the blank can be defined with the right mouse button. Using the Shift key creates horizontal or vertical lines. Using the Ctrl key creates arbitrary straight lines. The last point should be the same as the first point. The following points specify the blank outline: P1: -220, 730, 0 P2: 560, 730, 0 P3: 470, 265, 0 P4: 470, 20, 0 P5: -170, 20, 0 Input exact coordinates in the curve editor after generation of points with the right mouse button.


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Lesson 10: Use of Pad and Springback Outline > Edit ... > Curve Editor > Base > Select point with right mouse button > input in input fields X and Y > OK Fig. 10.8

Defined blank boundary Process

Process steps and tool movements are defined on the Process page:

Gravity

gravity > Gravity: Upwards > die: Stationary > pad: Stationary It is recommended to define pad during gravity as being Stationary. If the pad is specified as being Non-active, this tool would not be checked for contact during the gravity process. This means that an intersection of pad and sheet could occur. In a following process step, the pad would be activated and the intersection would cause a stop of the simulation run. To avoid this problem it is therefore recommended to set pad Stationary (Fig. 10.9).


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Process step gravity It is recommended to set pad Stationary during closing because of reasons mentioned above (Fig. 10.10).

Binder wrap

Closing > Tools > Show all > pad: Stationary


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Process step closing Deep drawing

During forming, the punch moves until it makes contact with the pad. The pad is then set as force–controlled and it will be moved by the punch until the punch closes with the die and the sheet is fully formed. For this procedure several process steps are required: • Punch moves until it makes contact with the pad, • punch moves until closing with the die and the pad is completed (force controlled). This means that the process step drawing must be interrupted, as soon as the punch is in contact with the pad. The distance between these tools is 390 mm (see Tools page Move value). Therefore, the punch must move for 390 s (tool velocity is 1 mm/s – see Tool control v=1).


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Lesson 10: Use of Pad and Springback Name: drawing > Tool control > Show all > die: Stationary > punch > Displcmnt > Velocity: 1 > Set binder > Force > Relative tool: die > Const pressure > Value: 2 > Set pad Stationary

Process

Duration > During time > Time: 390 (Fig. 10.11) Fig. 10.11

Process step drawing After the above step is completed, deep drawing must be finished in an additional process step: Add process step ... > Forming > Use settings of forming step: drawing > Insert position > Insert after > drawing > Add process step A new subpage appears which has to be completed (Fig. 10.12). In this process step, the punch continues to move until it reaches the bottom down position and displaces pad. www.forum.alghaform.com

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Process step drawing2 Process

Process step > Name: drawing2 > Type: Drawing > die: Stationary > punch > Displcmnt > Velocity: 1 > Set > binder > Force > Relative tool: die > Const pressure > Value: 2 > Set > pad > Force > Relative tool: punch > Const pressure > Value: 2 > Set (Fig. 10.13) > Duration > During time > Time: 110 (Fig. 10.12)


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Pad is force–controlled; punch is the counter tool. Attention: Attention The pad is also now force–controlled. For this tool no column has been defined yet. If this is required, it must be done on the Tools page (e.g. Columns > Tool center). center

Springback A new process step must be added to simulate springback. Add process step ... > Springback > Add process step The input page for the springback is very simple, no additional input is required. Control page The inputs on Control page should be checked in Binding effects: ThickSheet/Springback in later restart > ON Layers > 7 WriteRestart > Off (Fig. 10.14).


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Setups on Control page Start simulation run: Job > Start simulation ... > Start job > Program: af_3.1 > Start

Analysis of Springback After simulation run is completed successfully, reopen the simulation file: File > Reopen ... To analyze springback results, we need to go to the end of the simulation stage. Time > Springback ... Switch on the springback result menu: www.forum.alghaform.com

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Lesson 10: Use of Pad and Springback Results > Springback … Following menu appears: Fig. 10.15

Springback menu The part has to be fixed to avoid any rigid body motion. Therefore 6 boundary conditions must be specified. The first three fix the part in z–direction, the next two fix the part in y–direction and the last fixes the part in x–direction. A part in space has 6 degrees of freedom (three rotational degrees of freedom and three translations); to fix the part, we need to use the Springback menu (Fig. 10.15). The first three points fix the first three degrees of freedom (rotation around x–axis, rotation around y–axis and translation in z–direction). The next two points fix the translation in y–direction and rotation around the z–axis. The last point fixes the translation in x– direction. The first three points should be positioned so that they define a plane, which has very little springback and which has only a small angle to the xy–plane. We choose the middle area and position the first three points. Set Z1 > Define point with right mouse button A menu appears (Fig. 10.16), saying that for definition of points the increment before has to be used. www.forum.alghaform.com

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Lesson 10: Use of Pad and Springback OK Repeat for Z2 and Z3. The position is shown in Fig. 10.17. Fig. 10.16

One increment back Fig. 10.17

Z1, Z1 Z2, Z2 Z3 are defined Points Y1 and Y2 should be positioned on a plane that has only a small angle to the xz–plane (Fig. 10.18).


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Y1, Y1 Y2 are defined Point X1 should be positioned on a plane that has only a small angle to xz–plane (Fig. 10.19). Fig. 10.19

X1 is defined After the 6 points have been defined (Fig. 10.20), press the button Adjust to start the calculation of a rigid body motion which minimizes the distances between the part and the defined points. Distances are shown in right area of the menu (Fig. 10.21).


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6 points from z–direction Fig. 10.21

Distances which remain after pressing Adjust Values shown in red are greater than sheet thickness. To display the springback results in the main display, switch on Normal displacement (Icon first row, right side). Adjust the scale to minimum/maximum values of simulation using following options: Results > Result variables … > Normal displacement Results > Ranges … > Min/Max Simulation > Dismiss www.forum.alghaform.com

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Lesson 10: Use of Pad and Springback The main display should be as shown in Fig. 10.22. Fig. 10.22

Springback results – Normal displacement



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Lesson 11: Hydromechanical Deep Drawing

2. 11 Lesson 11: Hydromechanical Deep Drawing In this lesson an example is described using a fluid for the forming operation. Only sheet metal forming processes can be simulated. Use the AutoForm–Hydro for tube hydro forming. Fig. 11.1

Tools for active hydro–mechanical deep–drawing It should be noted that the procedure to describe a hydro–mechanical forming process is the same as for a normal deep drawing process. The two differ in the process schedule which is taken into account on the Process page. Tool setup is similar to the double action processes, which means the die is below and the punch and the binder are located above. The die only consists of a flat binder ring and a die radius. Often, the binder also has a radius to allow pre–forming of the sheet into the binder opening due to the increase in pressure of the fluid below the sheet (Fig. 11.1).


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Preparation of simulation Open a new simulation file: File > New ... > in_lesson_11 > OK Fig. 11.2

File > Import ... > IGES > OK > in_lesson_02.igs > OK > Program: afmesh_3.1 > OK Fig. 11.3

Faces of the binder surface are selected Prepare > Select faces of binder (right mouse button) Now the selected patches have been defined as the binder, unselected patches are defined as the punch and all patches are defined as the die. www.forum.alghaform.com

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Lesson 11: Hydromechanical Deep Drawing Prepare Fillet

Check geometry for gaps Generate part boundary: Apply Check geometry for sharp edges Check radius: 2.00 > Check The message that (no) sharp edges have been found appears in log– window. Close with the Dismiss button.

Tip

Check the geometry for undercuts Use the Tip page to check the geometry for undercuts. The check is performed automatically; the results are shown in the main display. The geometry is free of undercuts.

Generate simulation input Model > Input generator ... > Simulation type: Incremental > Geometry refers to: punch side > OK The title is predefined but it can be changed. Tools

The definition of tools has to be modified for a hydro–mechanical deep drawing process. The die consists only of a flat binder ring with a die radius and a vertical wall down. Proceed as follows. First, delete the defined die geometry using: Input generator > Tools > die > Geometry > Delete data > Delete Now define the die using: Input generator > Tools > die > Geometry > Reference … > Pick faces > Activate all (Fig. 11.4)


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Lesson 11: Hydromechanical Deep Drawing Fig. 11.4

Menu: Reference tool geometry with activated option Pick faces Select faces of the punch, binder radius and punch radius (Fig. 11.5). Fig. 11.5

Geometry with selected punch faces, binder radius and punch radius Deactivate faces using Reference tools geometry > Deactivate Define die using Reference tools geometry > OK Geometry of the die is displayed in Fig. 11.6.


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Geometry of die The definition of the punch has already been done and there is no need to change this. Columns for the binder has to be defined. It is recommended to use Tool center Blank

The blank outline has been generated in CAD and can be imported. Use: Blank > Import > IGES > Use all > Rotate > OK (Fig. 11.7)

Fig. 11.7

Dialog: Import line(s) in_lesson_11_crv.igs > OK > Program: afmesh_3.1 > OK File in_lesson_11_crv.igs contains all curves that define the blank outline. Select three curves Curve 1, Curve 2 and Curve 3 in the menu Select curve and confirm with OK (Fig. 11.8). www.forum.alghaform.com

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Dialog: Select curve with selected curves Curve 1, 1 Curve 2 and Curve 3 Define two symmetry lines: Input generator > Blank > Add symmetry … > Click segment Select the horizontal part of the blank boundary and confirm with OK. Repeat for the vertical part of the blank boundary: Input generator > Blank > Add symmetry … > Click segment


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Lesson 11: Hydromechanical Deep Drawing Select vertical part of the blank boundary and confirm with OK (Fig. 11.9 and Fig. 11.10). Fig. 11.9

Blank page of Input generator


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Blank boundary with two symmetry lines A double action process is already defined on the Process page. This means that first the binder closes and then the punch moves until bottom down. Duration of the process steps depends on the tool position (Move on Tools page). This has already been defined for this example.

Process


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Process page of Input generator Input for Gravity (Fig. 11.12): Process > gravity > Gravity: downwards > die: Stationary


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Process page of Input generator – subpage gravity


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Lesson 11: Hydromechanical Deep Drawing Process step binderwrap (closing) is already defined (Fig. 11.13). Fig. 11.13

Process page of Input generator – subpage closing In the active hydro–mech process, the blank will be preformed into the binder opening due to increasing pressure of the fluid from below the sheet. The sheet thus gets a uniform strain distribution. Therefore a new process step has to be inserted after the process step closing: Add process step ... > Forming > Use default setting of forming step: > drawing > Insert position > Insert after > closing > Add process step A new process step is added. Now change the process step type to Hydro mech. Process step > Type: Hydro mech www.forum.alghaform.com

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Lesson 11: Hydromechanical Deep Drawing On the right side of this option a selection of different fluid–based forming options appears (Fig. 11.14). Menu to define a fluid based forming step • Type: Hydro mech, switches to fluid based forming process´. • Passive: Pressure increase is due to punch movement and volume reduction. • Active pressure: Pressure increase is controlled by valves. • Active volume: similar to Active pressure, but volume change is defined. • Active height: similar to Active pressure, but dome height is defined.

Fig. 11.14

Define the pre–forming step with a dome height of 20mm and change the binder pressure to 20 N/mm² to avoid any draw–in of the material. Name: pre_forming > Type: Hydro mech > Active height Tools > die: Stationary > punch: Non-active > Binder > Force > Relative tool: die > Const pressure > Value: 20 > Set > Hydro mech: > Delta h: 20 > Below The fsluid pressure comes from the negative z–direction (Fig. 11.15).


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Added process step for pre–forming of active hydro mech No real die exists for hydro mechanical deep drawing. The blank is clamped between the force–controlled binder and the die ring, the punch deforms the sheet and from below the sheet an active pressure acts. This pressure presses the sheet against the punch and the desired geometry can be formed. This has to be defined in the Input. Define process step type Hydro mech for process step drawing. It should be defined as active hydro mech. The pressure should be controlled to 0.8 N/mm² during the first 475 mm punch stroke and then increasing linearly to 5 N/mm² until bottom down (500 mm punch stroke). Binder pressure should be 2 N/mm² to allow material flow.


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Lesson 11: Hydromechanical Deep Drawing Proceed as follows: Name: drawing > Type: Hydro mech > Active pressure Tools > die: Stationary > punch > Displacement > Velocity: 1 > Binder > Force > Relative tool: die > Const pressure > Value: 2 > Set Hydro mech: Active pressure > Time variable > From start > Time: 0, 475, 500 > Pressure: 0.8, 0.8, 5 > Set (Fig. 11.16) Fig. 11.16

Menu: Active pressure with specified pressure • • • • •

End p: End pressure in N/mm² Time variable: Pressure depending on process time From Start: Time is measured from process start. From End: Time is measured from process end. At End: Last specified time is moved to process end.

Define the lower side of the sheet as side where the fluid pressure acts. Hydro mech > Below (Fig. 11.17)


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Process page of Input generator – page drawing Definition of all necessary input option is completed. Start the Simulation Job > Start simulation ...



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AutoForm Incremental

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