PNEUMATIC SHEET METAL CUTTING MACHINE A PROJECT REPORT Submitted by
VINODHKANNA.G VINOTHKUMAR.S YUVA NAVEEN.B
(090111107110) (090111107111) (090111107115)
In partial fulfillment for the award of the degree of
BACHELOR OF ENGINEERING IN MECHANICAL ENGINEERING HINDUSTHAN COLLEGE OF ENGINEERING AND TECHNOLOGY COIMBATORE – 32
ANNA UNIVERSITY :COIMBATORE APRIL 2012
ANNA UNIVERSITY :COIMBATORE - 32 BONAFIDE CERTIFICATE
Certified that this project report “PNEUMATIC SHEET METAL CUTTING MACHINE” is the bonafide work of “VINODHKANNA.G, VINOTHKUMAR.S, YUVA NAVEEN.B”who carried out the project work under my supervision.
SIGNATURE Mr.C.NITHYANANDAM M.E., Ph.D* ASSISTANT PROFESSOR Department of Mechanical Engineering HINDUSTHAN COLLEGE OF ENGINEERING AND TECHNOLOGY, COIMBATORE – 32
SIGNATURE Dr.K.GANESH BABU M.TECH., Ph.D HEAD OF THE DEPATMENT Department of Mechanical Engineering HINDUSTHAN COLLEGE OF ENGINEERING AND TECHNOLOGY, COIMBATORE - 32
Submitted for the University viva-voce held on
INTERNAL EXAMINER
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EXTERNAL EXAMINER
ACKNOWLEDGEMENT The elementary buildings blocks to the overall module, my project owe its being to numerous genius personalities. I convey my humblest thanks with deep sense of gratitude to all those who helped me, without which I would be falling in my duty. I wish to place on record my sincere thanks and gratitude to managing trustee Mrs.K.SARASWATHY KHANNAIYAN her patronage and leadership which has helped meto carry out this project. I deeply in debt and express my profund gratitude to my guide and principal Dr.V.DURAISAMY,M.E.,PH.D., for providing me all facilities necessary to finish this project. I would sincerely thank my beloved head of the department Dr.K.GANESH BABU,M.E.,Ph.D., Department of mechanical Engineering who motivated me by his preserving guidance and sustained interest in the project. We express our grateful thanks to Mr. C.NITHYANANDAM,M.E.,Ph.D* Assistant professor Department Of Mechanical Engineering for his valuable guidance and fruitful encouragement throughout the duration of doing this project. We are very much grateful to Mr.R.Saminathan,ITI.,Lab assistant Department Of Mechanical Engineering for providing mightly support, valuable suggestions, timely co-operation and countless help till the successful completion of the project. Finally thank to all our staff member of mechanical engineering and friends who have directly or indirectly supported us throughout the project.
CONTENTS CHAPTER
TITLE
P.NO
1.
INTRODUCTION
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1.1.
SHEET METAL
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1.2.
SHEET METAL CUTTING
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2.
COMPONENTS USED
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3.
SPECIFICATIONS
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4.
PNEUMATIC CYLINDERS
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5.
DOUBLE ACTING CYLINDER
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6.
TW0-WAY DIRECT VALVE
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7.
MATERIALS
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8.
SHEARED EDGE
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8.1.
SHEARING
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9.
PNEUMATIC TRANSMISSION OF ENERGY
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9.1.
CONTROL OF PNEUMATIC ENERGY
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9.2.
CONTROL OF PRESSURE
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9.3.
CONTROL OF PRESSURE AFTER A COMPRESSOR 13
10.
WORKING
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11.
APPLICATIONS
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12.
ADVANTAGES
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13.
COST ESTIMATION
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14.
PHOTOGRAPHY
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15.
BIBILOGRAPHY
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ABSTRACT
We are using scissors for simple sheet metal cutting. It is a manual method so that sheet metals are to be wasted sometime because of mistakes happened such as wrong dimensions etc., and also even a simple cutting may take long time.Hydraulic machines are also available for sheet metal cutting. But this method is used for only heavy metal cutting and its cost is very high.We are using a pneumatic system for sheet metal cutting in a easy way. It is operated by a pneumatic hand lever of two way control valve.Control valve is operated by a compressor.
1. INTRODUCTION
1.1 . SHEET METAL: Sheet metal is simply a metal formed into thin and flat pieces. It is one of the fundamental forms used in metal working and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material. Thicknesses can vary significantly, although extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate. Sheet metal is available in flat pieces or as a coiled strip. The coils are formed by running a continuous sheet of metal through a roll slitter. The thickness of the sheet metal is called its gauge. Commonly used steel sheet metal ranges from 30 gauge to about 8 gauge. The larger the gauge number, the thinner the metal. Gauge is measured in ferrous (iron based) metals while nonferrous metals such as aluminum or copper are designated differently; i.e., Copper is measured in thickness by Ounce. There are many different metals that can be made into sheet metal, such asaluminium, brass, copper, steel, tin, nickel and titanium. For decorative uses, important sheet metals include silver, gold and platinum (platinum sheet metal is also utilized as a catalyst.) Sheet metal also has applications in car bodies, airplane wings, medical tables, roofs for buildings (Architectural) and many other things. Sheet metal of iron and other materials with high magnetic permeability, also known as laminated steel cores, has applications in transformers and electric machines. Historically, an important use of sheet metal was in plate armor worn by cavalry, and sheet metal continues to have many decorative uses, including in horse tack. Sheet metal workers are also known as "Tin Bashers",("Tin Knockers") which is derived from the hammering of panel seams when installing tin roofs. There are three primary procedures in Layout 1. Parallel 2. Radial 3. Triangulation 1
1.2. SHEET METAL CUTTING: Cutting processes are those in which a piece of sheet metal is separated by applying a great enough force to cause the material to fail. The most common cutting processes are performed by applying a shear force, and are therefore sometimes referred to as shearing processes. When a great enough shearing force is applied, the shear stress in the material will exceed the ultimate shear strength and the material will fail and separate at the cut location. This shearing force is applied by two tools, one above and one below the sheet. Whether these tools are a punch and die or upper and lower blades, the tool above the sheet delivers a quick downward blow to the sheet metal that rests over the lower tool. A small clearance is present between the edges of the upper and lower tools, which facilitates the fracture of the material. The size of this clearance is typically 2-10% of the material thickness and depends upon several factors, such as the specific shearing process, material, and sheet thickness. The effects of shearing on the material change as the cut progresses and are visible on the edge of the sheared material. When the punch or blade impacts the sheet, the clearance between the tools allows the sheet to plastically deform and “rollover” the edge. As the tool penetrates the sheet further, the shearing results in a vertical burnished zone of material. Finally, the shear stress is too great and the material fractures at an angle with a small burr formed at the edge. The height of these portions of the cut depends on several factors, including the sharpness of the tools and the clearance between the tools.
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2. COMPONENTS USED
Double acting cylinder Pneumatic hand operated valve High speed steel blade
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3. SPECIFICATIONS
PNEUMATIC CYLINDER Stroke length = 150mm Diameter = 50mm Pressure = 10bar
SHEET CUTTER = 8inch
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4.PNEUMATIC CYLINDER Pneumatic cylinders (sometimes known as air cylinders) are mechanical devices which use the power of compressed gas to produce a force in a reciprocating linear motion. Like hydraulic cylinders, pneumatic cylinders use the stored potential energy of a fluid, in this case compressed air, and convert it into kinetic energy as the air expands in an attempt to reach atmospheric pressure. This air expansion forces a piston to move in the desired direction. The piston is a disc or cylinder, and the piston rod transfers the force it develops to the object to be moved. Engineers prefer to use pneumatics sometime because they are quieter, cleaner, and do not require large amounts or space for fluid storage. Because the operating fluid is a gas, leakage from a pneumatic cylinder will not drip out and contaminate the surroundings, making pneumatics more desirable where cleanliness is a requirement. For example, in the mechanical puppets of the DisneyTiki Room, pneumatics are used to prevent fluid from dripping onto people below the puppet.
Figure (i)
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5. DOUBLE-ACTING CYLINDER Double-acting cylinders (DAC) use the force of air to move in both extend and retract strokes. They have two ports to allow air in, one for outstroke and one for in-stroke. Stroke length for this design is not limited, however, the piston rod is more vulnerable to buckling and bending. Addition calculations should be performed as well by using design data hand book using some relations between cylinder and pressure we can accurately find out bending and buckling of tie rod. 5.1. 2D VIEW:
Figure (ii)
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6. TWO WAY DIRECTIONAL VALVE A two-way directional valve consists of two ports connected to each other withpassages, which are connected and disconnected. In one extreme spool position, portA is open to port B; the flow path through the valve is open. In the other extreme,the large diameter of the spool closes the path between A and B; the flow path isblocked. A two-way directional valve gives an on-off function. (Flow path open and Flow path closed).
Figure (iii)
HIGH SPEED STEEL BLADE: A blade is used to cut the sheet metal in a desired dimension. Here we are using high speed steel blades to cut the sheet metal.
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7. MATERIALS
7.1 .Stainless steel: The three most common stainless steel grades available in sheet metal are 304, 316, and 410.
Grade 304 is the most common of the three grades. It offers good corrosion resistance while maintaining formability and weldability. Available finishes are #2B, #3, and #4. Note that grade 303 is not available in sheet form.
Grade 316 offers more corrosion resistance and strength at elevated temperatures than 304. It is commonly used for pumps, valves, chemical equipment, and marine applications. Available finishes are #2B, #3, and #4.
Grade 410 is a heat treatable stainless steel, but does not offer as good corrosion resistance. It is commonly used in cutlery. The only available finish is dull.
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8. SHEARED EDGE A varietyof cutting processes that utilize shearing forces exist to separate or remove material from a piece of sheet stock in different ways. Each process is capable of forming a specific type of cut, some with an open path to separate portion of material and some with a closed path to cut out and remove that material. By using many of these processes together, sheet metal parts can be fabricated with cut outs and profiles of any 2D geometry. Such cutting process include the following
Shearing – Separating material into two parts Blanking – Removing material to use for parts Conventional blanking Fine blanking Punching – Removing material as scrap Piercing Slotting Perforating Notching Nibbling Lancing Slitting Parting Cutoff Trimming Shaving Dinking
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Figure (iv)
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8.1. SHEARING As mentioned above, several cutting processes exist that utilize shearing force to cut sheet metal. However, the term “shearing” by itself refers to a specific cutting process that produces straight line cuts to separate a piece of sheet metal. Most commonly, shearing is used to cut a sheet parallel to an existing edge which is held square, but angled cuts can be made as well. For this reason, shearing is primarily used to cut sheet stock into amaller sizes in preparation for other processes. Shearing has the following capabilities Sheet thickness: 0.005 – 0.25 inches Tolerence: 0.1 inches The shearing is performed on a shear machine, often called asquaring shear or power shear, that can be operated manually or by hydraulic, pneumatic, or electric power. A typical shear machine includes a table with support arms to hold the sheet, stops or guides to secure the sheet, upper and lower straight edge blades, a gauging device to precisely position the sheet. The sheet is placed between the upper and the lower blade, which are then forced together against the sheet, cutting the material. In most devices, the lower blades remain stationary while the upper blade is forced downward. The upper blade is slightly offset from the lower blade, approximately 5 – 10% of the sheet thickness. Also the upper blade is usually angled so that the cut progresses from one end to the other, thus reducing the required force. The knife edge and are available in different materials, such as low alloy steel and high carbon steel.
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9. PNEUMATIC TRANSMISSION OF ENERGY: The reason for using pneumatics, or any other type of energy transmission on amachine, is to perform work. The accomplishment of work requires the applicationof kinetic energy to a resisting object resulting in the object moving through adistance. In a pneumatic system, energy is stored in a potential state under the formof compressed air. Working energy (kinetic energy and pressure) results in apneumatic system when the compressed air is allowed to expand. For example, atank is charged to 100 PSIA with compressed air. When the valve at the tank outletis opened, the air inside the tank expands until the pressure inside the tank equals theatmospheric pressure. Air expansion takes the form of airflow. To perform any applicable amount of work then, a device is needed which cansupply an air tank with a sufficient amount of air at a desired pressure. This deviceis positive displacement compressor. What a Positive Displacement Compressor Consists of A positive displacement compressor basically consists of a movable member insidea housing. The compressor has a piston for a movable member. The piston isconnected to a crankshaft, which is in turn connected to a prime mover (electricmotor, internal combustion engine). At inlet and outlet ports, valves allow air toenter and exit the chamber. How a Positive Displacement Compressor Works: As the crankshaft pulls the piston down, an increasing volume is formed within thehousing. This action causes the trapped air in the piston bore to expand, reducing itspressure. When pressure differential becomes high enough, the inlet valve opens,allowing atmospheric air to flow in. With the piston at the bottom of its stroke, inletvalve closes. The piston starts its upward movement to reduce the air volume whichconsequently increases its pressure and temperature. When pressure differentialbetween the compressor chamber and discharge line is high enough, the dischargevalve opens, allowing air to pass into an air receiver tank for storage.
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9.1. Control of Pneumatic Energy: Working energy transmitted pneumatically must be directed and under completecontrol at all times. If not under control, useful work will not be done and machineryor machine operators might be harmed. One of the advantages of transmittingenergy pneumatically is that energy can be controlled relatively easily by usingvalves. 9.2. Control of Pressure: Pressure in a pneumatic system must be controlled at two points - after thecompressor and after the air receiver tank. Control of pressure is required after thecompressor as a safety for the system. Control of pressure after an air receiver tankis necessary so that an actuator receives a steady pressure source without wastingenergy. 9.3. Control of Pressure after a Compressor: In a pneumatic system, energy delivered by a compressor is not generally usedimmediately, but is stored as potential energy in air receiver tank in the form ofcompressed air. In most instances, a compressor is designed into a system so that it operates intermittently. A compressor usually delivers compressed air to a receiver tank untilhigh pressure is reached, then it is shut down. When air pressure in the tankdecreases, the compressor cuts in and recharges the tank. Intermittent compressoroperation in this manner is a power saving benefit for the system. A common way of sensing tank pressure and controlling actuation and deactuationof relatively small (2-15 HP) compressors, is with a pressure switch.
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10. WORKING The pneumatic machine includes a table with support arms to hold the sheet, stops or guides to secure the sheet, upper and lower straight - edge blades, a gauging device to precisely position the sheet. The table also includes the two way directional valve. The two way directional valve is connected to the compressor. The compressor has a piston for a movable member. The piston isconnected to a crankshaft, which is in turn connected to a prime mover (electricmotor, internal combustion engine). At inlet and outlet ports, valves allow air toenter and exit the chamber. When the compressor is switched ON, the compressed air is flow to inlet of the pneumatic cylinder. The sheet is placed between the upper and the lower blade. The lower blade remains stationary while the upper blade is forced downward. The upper blade is slightly offset from the lower blade, approximately 5 – 10% of the sheet thickness. Also the upper blade is usually angled so that the cut progresses from one end to the other, thus reducing the required force. When the pneumatic hand operated lever is moved forward, the piston starts moving in the forward direction. The upper blade which are then forced against the sheet, cutting the material. When the pneumatic hand operated lever is moved backward, the upper blade will come to the original position (i.e., the upper blade will move upwards). After the material is cut, adjust the pneumatic hand lever to the mid position (i.e., normal position) and then the compressor is switched OFF.
Figure (v) 14
11. APPLICATIONS Sheet metals are used in
Car bodies Airplane wings Medical tables Roofs for buildings (Architectural) and many other things Sheet metal of iron and other materials with high magnetic permeability, also known as laminated steel cores, has applications in transformers and electric machines. Historically, an important use of sheet metal was in plate armor worn by cavalry, and sheet metal continues to have many decorative uses, including in horse tack.
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12. ADVANTAGES
Low cost Less consumption of time Easy to handle Skilled labor is not required Less maintainance High accuracy Good surface finish Less floor space
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13. COST ESTIMATION
S.NO 1 2 3 4 5
COMPONENTS Sheet Cutter Pneumatic Cylinder Sheet Metal Angle Frame Pneumatic Valve + Hose Nipple Connector Total
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COST IN RUPEES 1700.00 1200.00 600.00 1000.00 4500.00
14. PHOTOGRAPHY
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15. BIBLIOGRAPHY
We made this project with our own idea with the help of “HYDRAULIC AND PNEUMATIC SYSTEM” written by Srinivasan, “TOTAL AUTOMATIVE TECHNOLOGY” written by Anthony E Schwaller, “INDUSTRIAL ENGINEERING AND THE ENGINEERING DIGEST” written by Robert Thurston Kent, Charles MaccaugheySomes
WEBSITES: www.pumpwork.in www.wikipedia.com www.howstuffworks,com
under the reference of our project guide.
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