MEP 100: Introduction to ENGINEERING VISUALIZATION Harish Hirani Associate Professor Block Blo ck II/3 II/354. 54. Dept Dept of Mech. Mech. Eng. Eng. I.I.T Delhi
0.5-0-3 Learn by Doing
Course Objectives To introduce students to: • Meth Method od of vi visu sual aliz izin ing g en engi gine neer erin ing g objects • Simple assemblies • CAD modeling and communicating them to other professionals.
Course Contents Sketching concepts. Orthographic Projections and views Principles of Axonometric projections and Development of Isometric
interpretation interpreta tion of drawings
Introduction of CAD package to construct a simple solid model
Dimensioning of Orthographic Views
Using a CAD package to construct solid models and generating orthographic, isometric, sectional views with dimensioning .
Sectioning in Orthographic views and assembly drawings
Assembly of components and generation of corresponding drawings. draw ings. Anim Animation ation of single single doff ma do mach chin ines es in in CAD CAD
2D TO 3D r
C
r
R r P
R r P
GRAPHI GRA PHICS: CS: Art or Sci Scienc ence e of of draw drawing ing Systematic knowledge-base practice capable of resulting in predictable type of outcome.
Drawing: Plane by Plane: 2D to 3D
3D by Sketching
Procedure to Sketch
Two stage extrusion
Two stage extrusion
Only extrusion ? • Learn Pro-E. • Think few simple shapes.
Projection: Graphical representation of 3-D object on 2-D media (Paper/screen)
Thick Lines Thin Lines
All projection lines are orthogonal to the projection plane:
Orthogonal Projections
Various Lines • Outline, Hidden, Center, Construction, – Dimension, Cutting plane, Phantom, break.
• Center line: – Where center lines cross, the short dashes should intersect symmetrically. – Center lines should not end at object lines.
• Line precedence: Outlines take precedence over all other lines, Hidden lines take precedence over centre lines.
Orthographic Projections
Y
X
Object in I quadrant = I angle Object in III quadrant = III angle Object in II or IV quadrant ??
Object in I quadrant = I angle
Object in III quadrant = III angle
ORTHOGRAPHIC PROJECTIONS: DIFFERENT VIEWS of an OBJECT are PROJECTED on DIFFERENT REFERENCE PLANES OBSERVING PERPENDICULAR to RESPECTIVE REFERENCE PLANE
Reference Planes:
Different Views:
Horizontal/Top Plane (HP / TP) Vertical/Front Plane ( VP /VP ) Side Or Profile Plane ( SP / PP)
Front View (FV) Top View (TV) Side View (SV)
FV is a view projected on VP. TV is a view projected on HP. SV is a view projected on PP.
FV TV SV
HP VP PP
FOR T.V.
First Angle projection
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
L.H.SIDE VIEW
x
Once F.V. (principal view) chosen, other views need to be arranged w. r. t. FV.
y
TOP VIEW
I angle III angle
Block View
All orthographic views must fit on the same sheet.
Space for: FV: 90, 50 TV: 90, 40 Space between FV & TV SV: 40, 50 Space between FV & SV (90+10+40) * (50+10+40)
Y
x
Most informative view of an object shall be used as the front view.
First angle projection method View in direction above FV, is placed underneath FV. View in direction below FV, is placed above FV. View seen from the right of FV, is placed on the left of FV. View seen from the left of FV, is placed on the right of FV.
Third angle projection method
Selection of Views • Only those views that are necessary for a clear & complete description should be selected. – Simple objects such as cylinder, bushing, etc. require only two views (FV & SV/TV). • Avoid (unnecessary) repetition of detail.
• Choose view which provide desired explanation with minimum number of hidden lines. – Invisible lines are represented with short dashes. Such line always starts with a dash in contact with the object line from which it starts, unless it forms a continuation of a visible line.
Primitive Shapes: basic shapes that can be used to make more complex structures.
Sheet Size
210 * 297
297* 420
A3 sheet for Sketching.
420* 594
A2 Sheet = (2*A3) for each lab No of Hours
Questions
Weightage
2
3-4
25%
1
2 (Simple+difficult)
75%
Book: Warren Luzadder and Jon M. Duff, 2009, Fundamentals of Engineering Drawing with an Introduction to Interactive Computer Graphics for Design and Production, 11 th Edition, PHI Learning.
594* 841
841 * 1189
FOR T.V.
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
L.H.SIDE VIEW
F T
TOP VIEW
DRAW THREE VIEWS OF THIS OBJECT BY FIRST ANGLE PROJECTION METHOD
Mistakes ??
FOR T.V.
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
F T
TOP VIEW
DRAW THREE VIEWS OF THIS OBJECT BY FIRST ANGLE PROJECTION METHOD
L.H.SIDE VIEW
FOR T.V.
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
Y
X
TOP VIEW
DRAW THREE VIEWS OF THIS OBJECT BY FIRST ANGLE PROJECTION METHOD
L.H.SIDE VIEW
FRONT VIEW
F T
TOP VIEW
L.H.SIDE VIEW
FRONT VIEW
F T
TOP VIEW
L.H.SIDE VIEW
Dimensioning • Lines, numerals, symbols, notes: – Dimension line: Thin continuous line. Terminated by arrowheads. – Extension line: Thin continuous line. ⊥ to feature
– Arrowhead: Closed/Open. Length = 3* Width. – Note: Specific info about feature. – Leader: Pointer connecting feature & note.
Dimensioning Symbols • φ : Diameter • Sφ : Spherical diameter • : Square • R : Radius • SR : Spherical radius • ∩ : Arc length
Procedure:
break part down into a series of geometric
features (hole, projection, etc.)
apply dimensions to size each of the features
(Functional dimensions) ,
apply dimensions to control the
features (Non-functional dimensions).
location
of the
Dimensioning Multi-features
Common mistakes
Dimensions 25, 40, and 12 are functional dimensions. Dimensions 20 and 12.5 are non-functional dimensions.
Common mistakes
Dimension lines should not end at object lines
Common mistakes
Each feature shall be dimensioned only once on a drawing. Each drawing shall use the same unit (i.e. mm) Centerline may be used in place of extension line.
Placing dimensions • Aligned system • Unidirectional system
All dimensions in Inches
Use metric system.
Aligned
Unidirectional
Place dimension (number) above line All dimensions can be read from so that it can be read from bottom edge of drawing. bottom/right hand edge of drawing Number is placed along line.
Scales
Scale shall be large enough to permit easy and clear interpretation of the information .
• Ratio of the linear dimension of an element of an object as represented in the drawing to the real linear dimension of the same element of the object itself. – Full size: 1:1 – Enlargement scale: 50:1; 20:1; 10:1; 5:1; 2:1. – Reduction scale: 1:2; 1:5; 1:10; 1:20; 1:50.
X: 1
1: X
FV 30
10
30
SV
30
10 30
x
DRAW THREE VIEWS OF GIVEN OBJECT BY FIRST ANGLE PROJECTION METHOD
y
TV
ALL VIEWS IDENTICAL!!!
FV 30
10
30
SV
30
10 30
x
PICTORIAL PRESENTATION IS GIVEN DRAW THREE VIEWS OF THIS OBJECT BY FIRST ANGLE PROJECTION METHOD
y
TV
ALL VIEWS IDENTICAL!!!
35
FV
35 10
x
20
10
30
10 40 70
TV
DRAW FV AND TV OF GIVEN OBJECT BY FIRST ANGLE PROJECTION METHOD
Mistakes !!!!!
y
DRAW FV AND TV OF GIVEN OBJECT BY FIRST ANGLE PROJECTION METHOD
ORTHOGRAPHIC PROJECTIONS
30
FV
R 10
50 35
R 15
0 3
10
X 10
10 R 30
R 10
0 5 5 3
TV
R 30
10
R 15 TOP VIEW
Y
Geometry with straight lines • Triangle 180 60° • Rectangle/Square 360 90° • Pentagon 540 108° • Hexagon 720 120° • Heptagon 900 128.57° • Octagon 1080 135° α
2
α
1
α 3
α
1
+ α 2 + α 3 = 180
α
= 135
o
Can we draw geometries without measuring angles ?
With any point O as centre and radius = OA, draw a circle.
B
C
D
From A draw a cord of length OA, which intersects circle at B.
Length OB will be ????
Equilateral triangle???
O Angle
E
A
CAB = 120
Method to make a hexagonal of side = AB.
B
E is middle point of line DB.
How to locate point 5: Bisecting Line 4-6
D
8 7
E
6
P
C
5 4 4
E 5
6
A
B
Line AB=BC=CD=DE=EA 43
Arc 1
Drawing Arc between two straight lines
Arc radius R = 10 mm
Drawing Arc (R 1) between Line & Arc (R 2)
Arc 3
Drawing Arc (R) between two Arc (R A & R B)
Procedure to Draw Orthographic Projections using dimensions T V
F V
R H S V All dimensions are in Inches
Axonometric projection Difference?
Plane
Possibility of a number of axonometric
Axonometric Projection • Dime Dimetr tric ic:: Ang Angle less bet betwe ween en tw two o of of axe axess are same. Two scale factors. • Tr Trim imet etri ric: c: Th Thre reee sc scal alee fa fact ctor ors. s.
• Isometric: ISO MEANS SAME, SIMILAR OR EQUAL. X, Y, Z are projected on three dimensional axes maintained at equal inclinations with each other (120° (120°). Size is reduced. Single scale factor.
Importance of Isometric Drawing • Understand overall shape, size & appearance of an object prior to it’s production production..
Vertical + 30 to HP - 30 to HP
Isometric drawing combined with orthographic projections provide complete Description.
SOME IMPORTANT TERMS: ISOMETRIC ISOMET RIC A XES an and d L INES INES::
Three li Three lines nes AL, AD and AH, mee meeti ting ng at point poi nt A and making maki ng 120 1200 angles with wi th each each ot other her are are termed Isometric Axes. Representation of three planes
A
H
Lin es parallel Line parallel to isom i some etri tric c axes axe s are called call ed Isometric Lines .
Lines for hidden edges are generally not shown.
FRONT VIEW of FIGURE requires H & L AXES. A
Vertical line will be drawn vertical, while horizontal line will be drawn inclined at 30 to horizontal.
TOP VIEW of FIGURE require D & L.
H Isometri c vie Isometric vi ew if t he Shape Shape is F.V. or T.V.
SHAPE H A
D D
RECTANGLE D
A C
C A
B
C
B
B
Making Isometric Drawing of Rectangular Object
H
F.V. L
D
T.V. Concept of block views
Shapes containing Inclined lines cannot be drawn parallel to any isometric axes. Angle do not increase or decrease in any fixed proportion. Enclose in a rectangle… First draw isom. of that rectangle and then inscribe that shape as it is.
Inclined Lines ???? Isometric view if t he Shape is F.V. or T.V.
SHAPE
B H TRIANGLE 1
B
3 B
3
1 A
3 2
A
A 1
2
2 4
H
PENTAGON E
1
4 D
A
E
1
D
4 D
E A
1 3 C
2
B
C
3
2
B
3 C
A B
2
Nonisometric Lines • Inclined lines (not parallel to isometric axes). – Distorted (cannot be measured directly) line. – Position & Projected length must be established by locating end points.
C
D TV
A FV
B
C A B
ISOMETRIC VIEW OF
HEXAGONAL PRISM STANDING ON H.P.
For hexagonal, angle is 120
Edge a Length (0.5+1+0.5) a Height (0.866 + 0.866) a
Isometric drawing for given orthographic projections.
Isometric Scale a’
b’ d’
c’
Scale
Scale h’ e’
f’
=
g’
=
0.707 0.866
cos 45 cos 30
= 0.816
d h
a
g c
e
o
Foreshortening is ignored Isometric drawing. Otherwise projection.
Angle cbp > angle obp Length bc > bo
f b
p
Lines for hidden edges are generally not shown
.
ISOMETRIC Drawing
60
FV
X
40
Draw isometric lines, then non-isometric
Y
20
TV
0 1
First angle orthographic projections O
F T
O
F.V., T.V. and S.V.of an object are given. Draw it ’s isometr ic view. ALL VIEWS IDENTICAL FV
SV
y
x 10
40
40 60
TV
60
Isometric Drawing of Curved features
Drawing circles ?? GIVEN: A circl e in FV REQUIRED: Isometric view. FIRST ENCLOSE IT IN A SQUARE. USE H & L AXES.
Four-centre Method: Ends of Small diagonal provides two Centers. Locate two centers on longer Diagonal Easier for free hand sketching.
Ellipse is made of four arcs.
DRAW ISOMETRIC VIEW of the figu re shown consi derin g it fi rst as FV and th en TV. 25 R
50 MM
IF FRONT VIEW 100 MM
IF TOP VIEW
CYLINDER, when Axis is Vertical
CYLINDER, When Axis is Horizontal
ISOMETRIC Drawing FV
30 10 30
30
50
+
50
TV
F.V. & T.V. of an object are given. Draw it ’s isometri c vi ew.
40
10
F T
30 25
25 10
50
O
80
Block of 80*50*10 Block of 25*25*40 Four center method to draw ellipse
F.V. & T.V. of an object are given. Draw it’s i sometr ic v iew.
40
FV
O
X
10
Y
100 10
10
30
10 25
25
O
30 R R 10
TV
Cuboid of 100*50*10 Draw parallel lines at 30 mm Cuboid of 50*25*40
Isometric Drawing of Curved features
F.V. & T.V. of an object are given. Draw it’s isometric view.
Block of 60*10*30
40
20
30
F T
10
O
10
30 10 30
O
Block of 80*40*10
80
5 1
15
First angle projection O
F.V. and S.V.of an object are given in I angle projectio n. Draw it’s i sometri c view.
Mistake ??
F.V. Sq 20 20
O
30
40
40
20
10
O 100
30 50 60
0 4
40
F.V. & T.V. of an object are given. Draw it’s isometric view.
50
F T 20
25
25
20
ORTHOGRAPHIC PROJECTIONS 10
10
25
25
X
Y
O
15
FV
50
LSV
10
what we need 1. Cutting plane 2. Part, assembly, any view.
Sectional Views Cross section Section Required to add information of surfaces that are represented by hidden lines in standard FV, TV, and SV.
79
Section (thin parallel) lined areas are those portions that came in actual contact with cutting plane. Visible parts behind the cutting plane are shown, but not hatched .
Section lines
Hatching Pattern
Continuous thin lines at convenient angle (preferably 45 ) to the principal outlines.
Spacing between the hatching lines should be chosen in proportion to the size of the hatched areas, provided that the requirement for minimum spacing are maintained.
Common Mistakes
Full section view
NOTES
• Sectional views are always viewed in the direction defined by cutting plane arrows.
• Any hidden surface that is behind cutting plane is not included in sectional view.
Hatch lines represent location of cutting plane passing through solid material. 84
Full & Half section views
Example: Sectional Orthographic Views A
A
Mistakes in dimensioning? Representation of cutting plane?
86
Section B-B a
b
c
Rib not sectioned
Common mistake is to omit back edge
Section A-A
Sectional view of Ribs
Ribs add strength and rigidity to an object. Usually narrow.
88
Pg. 167 Luzadder book Keyway
Front view
• Although the spoke is in line with the front view, it can give the impression that it is a stunted spoke •
Full length of spoke is shown to indicate the structure. It should be shown along with front view to indicate the number of spokes and angles between them 89
Revolved sections Cutting plane
Section rotated 90o so that exact shape can be viewed
90
Examples of Revolved Sections
Revolved sections examples show the shape of an object’s cross-section superimposed on a longitudinal view
Removed Sections A
Removed sections are like revolved sections but moved aside.
Section B-B
Section A-A
A
B B
Section C-C
C
C
Offset Sections • Cutting plane lines need not be drawn as straight lines Stepped line Include as many features as possible without causing confusion
Offset full section
93
Countersunk hole
94
Choosing Full/Half/Broken sectional view Half & Partial sectional view vi ews s ----- al allo low w showing outer and inner features on the same figure. Normal half/partial orthographic projection may include hidden lines. Broken line is a freehand line. 95
Cutting Plane Lines
Phantom line
96
Section B-B
Section A-A
ALIGNED SECTIONS • To include, in a section, certain angled elements, cutting plane may be bent so as to pass through those features. – Plane & feature are aligned into original plane.
98
Summary • When a part is cut fully in half, the resulting view is called a full section. • A line called the cutting-plane line shows where the object was cut and from which direction the section is viewed. – The arrows point toward the section being viewed.
• In section view, the areas that would have been in actual contact with the cutting plane are shown with section lining. • Visible edges of the object behind the cutting plane are generally shown because they are now visible but they are not cross-hatched. • Section views can replace the normal top, front, side, or any other standard orthographic view.
Summary Labeling !!
• When a cutting plane coincides with a center line, the cutting plane line takes precedence. • Omit hidden lines in section views. • A section-lined area is always completely bounded by a visible outline
Summary
• To avoid a false impression of thickness and solidity, ribs/webs, gear teeth, and other similar features are not hatched with section lining even though the cutting plane slices them.
• Sectional views are important for assemblies.
3-D Solid Models Sheet 8-13
102
103
104
105
Assembly
Subassembly
Component / Part
106
Ho w t o c r eat e s o l i d m o d el i n A u t o d es k
Extrusion
• Select New > New , to make the sketch
• To start with select Metric > Standard (mm).ipt
Standard format with datum plane & Coordinate system. Dimensions in mm
• The following screen will be open to draw the sketch.
Choose line command to initialize the drawing
• After drawing a line provide the required dimension by choosing dimension option in panel, and clicking on the line.
Dimensions !!!! Before completing sketch ?????
• To provide angular dimension, select lines between which the angle is to be given.
• Complete the sketch by above mentioned tools.
Make sure sketch is closed i.e. there should be no free ends in the sketch.
Press finish when sketch is competed.
• Press extrude to make a solid out of sketch
• Distance = part thickness.
•The arrow shows the direction of material addition.
• To change the direction of the material addition click on the icon shown in the extrude command.
To finish your model click “OK”.
Software Autodesk Inventor Professional • Available in CSC window machines (9am – 9 pm). • Students can download software from http://students.autodesk.com/?nd=download_center
• Register using email id and get license key. • Evaluation: – Submit print-out of drawings. One page per question. • How do I make title block • Import (download) mep100.dwg format. 117
Open Autodesk Inventor>click on new>metric>MEP100_A4>OK
Zoom in the title block at bottom right corner
Click annotate>text and click near the name field
Write your name and click OK
Similarly write entry no., group no. and lab no. to complete the title block
Complete the title block and zoom out to place the views
To create the drawings click Place Views>Base>file>orientation>style>ok
Place views and right click to create
Block views
Click Dimension > select entity > set precision
Complete dimensioning and save the file then print
• Extrusion – Cut • Loft (Connecting different cross sections) • Ribs • Datum Planes • 2D to 3D
Topics
Starting Autodesk Inventor
Starting with Top plane Make solid model of orthographic projection given below and obtain orthographic views using mep100.dwg. Step 1: Go to New and choose Standard(mm).ipt
Step 2: Choose top plane to start the sketch. Use Model tree to select it. Draw a square of side 70mm
Step 3: Finish sketch and extrude the sketch
Step 4: Select the extruded surface to sketch on it
Step 5 :Draw a circle of 60 mm diameter and extrude it
Step 6: Select the extruded surface to sketch a square of 25mm on it. Finish the sketch
Step 7: Take a plane offset by 40 mm from the sketch plane.
Step 8: Select the offset plane to sketch a point in the middle
Step 9: Use loft command. First select the square sketch and then the point on offset plane and a loft will be created . Save the Part model.
Step 10: Go to drawing by Selecting ‘Drawing option’ from New command window. And select Base to place orthographic views.
Step 11: Select the part model for which orthographic views are required
Step 12: Place orthographic views and right click on a view to select create.
Step 13: From Annotate option choose dimension for dimensioning of orthographic views. Save the file after dimensioning is complete.
Draw the top view in the sketch and extrude it
Select the top surface for sketch and draw two circles and extrude them for the holes
Select the side surface and draw circles at a distance of 80 m from top surface. Extrude it.
Select the same surface for sketch and draw the profile as shown and extrude it
Select the side plane for sketch (which is passing through centre of circles). Select a line right click on sketch plane to make sure that Auto Project is on
Draw a line passing through intersection of two surfaces as shown by white lines representing intersection of rib.
Finish the sketch and select Rib command.
Select the lines for profile of Rib. Make sure Parallel to Sketch Plane option is selected. Give Rib thickness and press OK.
As the mid surface is chosen for sketch Rib thickness should be provided on the mid surface.
Obtain orthographic views and dimension them
Draw two squares and extrude them
Select a surface and draw a square of side 40mm and extrude it
Repeat the procedure on remaining surface to get a part as shown
Obtain orthographic projections and dimension those
TOPICS Other than extrusion
PATTERN LOFT CONSTRAINTS REVOLVE SHELL SPLIT COMBINE SPLINE SWEEP
Features appearing more than once
How I make it ?????
LINEAR PATTERN
Making a Chocolate !!!!
RECTANGULAR PATTERN !!
CIRCULAR PATTERN
Pattern
Creating Datum Plane
Pattern
Visibility
Rectangular Pattern
Circular Pattern
Sketches on Datum planes
Loft
Revolve
Revolve
Section + Path
Sweep
Assembly
On clicking
Assembly Sub-assembly Components
Construction of Assembly Step 1: Gather components in an assembly file. Step 2: Assemble components by applying appropriate assembly constraints. Design Approaches Bottom up Top down Hybrid
Bottom Part Top Assemble
Top Down
Bottom Up Six numbers of part2
Hybrid
Query: Meaning of constraint? Constraint = Restriction. Applied to 2D or 3D geometry. Two types of constraints: dimensional & geometric. Dimensional constraints are used to control the length, angle, radius etc. Geometric constraints are used to control the relationships of objects in respect to each other.
•Press constraint
Query: Assembly constraints? Assembly constraints determine how components in the assembly fit together. As you apply constraints, you remove degrees of freedom, restricting the ways components can move and positioning them relative to one another.
located near the top of the left column Now select a constraint which you need (for example Mate, Angle, Tangent, and Insert)
MATE Mate: makes the selected planes face each other and coincide (they are become the same plane) Flush: makes the selected planes face the same direction and coincide A mate constraint causes two selected objects (face, edge, vertex) to mate (opposite direction) or flush (same direction). Face to a face An edge to an edge A point to a point An edge to a face A vertex to a face A vertex on an adge
Mate
Mateoffset ??
Mate
Mate-Mate + Mate-offset_flush
TANGENT
Example
Angle
INSERT
Drawing….
Assembly • Part 1……. Part n. – Color Assign to selection
Parameters & Relationship • Dimension is a parameter.. D0, d1, d2, ……….. • Relationship may be made in parameters. – Length by diameter should be 10.
Parameters & Relationship….
No change !!!
Threads
Threads… Internal
Assembly – Threaded Connection
Axial Align Movement along the axis is possible.
Threaded Connection Insert. Rotation is possible.
Suppress
Checking Degrees of Freedom
Section • Choose/Make work feature plane.
Offset ???
Bolted Connections
Bolted Connections
Exploded View…. Part of presentation • After assembly.
How do I Start
Now define the coordinate system about which part is going to displace First select the direction then the component Each time you have to define the coordinate system for tweaking different components and if you don't define the coordinate system, then Software will take the last coordinate system which you have defined.
