43-sheet Metal Punching Machine 4nr1e

SHEET METAL PUNCHING MACHINE

SYNOPSIS

Here we have fabricated the punching machine with a new innovative concept. This machine has been mainly developed for sheet metal fabricating industries. Here we are using the rack and pinion mechanism for the punching operation. CHAPTER 1 INTRODUCTION The press is a metal forming machine tool, designed to shape or cut metal by applying mechanical force or pressure with help of press tool. The metal is formed to desired shape without removal of chips. Press tools are exclusively intended for mass production work. Sheet metal operation plays an important role in engineering works. Press tool are made to produce a particular component in very large numbers, mainly out of sheet metal. The principle press tool operations are punching and forming operations of sheet metal.

Sheet metal punching comes

under the category of Metal working. Metalworking is craft and practice of working with metals to create individual parts, assemblies, or large scale structures. The term covers a wide range of work from large ships, bridges and oil refineries to delicate jewelry. It therefore includes a correspondingly wide range of skills and the use of many different types of metalworking processes and their related tools. Metalworking is an art, hobby, industry, and trade. It relates to metallurgy, a science, jewelry making, an art-and-craft, and as a trade and industry with ancient roots spanning all cultures and civilizations. Metalworking had its beginnings millennia in the past. At some imprecise point in the distant past humankind discovered that certain rocks now called ores could be smelted,

producing metal. Further, they discovered that the metal product was malleable and ductile and thus able to be formed into various tools, adornments and put to other practical uses. Humans over the millennia learned to work raw metals into objects of art, adornment, practicality, trade, and engineering.

Sheet metal components such as automobile parts, parts of house hold appliances and electronic equipments are produced by press tools.Nowadays lot of sheet metals parts are being utilised in lot of sectors irrespective of particular fields like mechanical, electrical, electronics, computers. Sheet metal components are mainly used for the followings,  Lesser in weight  Less Expensive  Replaceable and better aesthetics

CHAPTER 2 LITERATURE REVIEW 2.1 INTRODUCTION Sheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, 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. 2.2 SHEET PROCESSING The raw material for sheet metal manufacturing processes is the output of the rolling process. Typically, sheets of metal are sold as flat, rectangular sheets of standard size. If the sheets are thin and very long, they may be in the form of rolls. Therefore the first step in any sheet metal process is to cut the correct shape and sized ‘blank’ from larger sheet. 2.3 SHEET METAL PROCESSES Sheet metal processes can be broken down into two major classifications and one minor classification.  Shearing processes: Processes which apply shearing forces to cut, fracture, or separate the material.  Forming processes: Processes which cause the metal to undergo desired shape changes without failure, excessive thinning, or cracking. This includes bending and stretching.  Finishing processes: Processes which are used to improve the final surface characteristics. 2.3.1 Shearing Processes 1. Punching: Shearing process using a die and punch where the interior portion of the sheared sheet is to be discarded. 2. Punching: Shearing process using a die and punch where the exterior portion of the shearing operation is to be discarded.

3. Perforating: Punching a number of holes in a sheet 4. Parting: Shearing the sheet into two or more pieces 5. Notching: Removing pieces from the edges 6. Lancing: Leaving a tab without removing any material 2.3.2 Forming Processes 1. Bending: Forming process causes the sheet metal to undergo the desired shape change by bending without failure. 2. Stretching: Forming process causes the sheet metal to undergo the desired shape change by stretching without failure. 3. Drawing: Forming process causes the sheet metal to undergo the desired shape change by drawing without failure. 4. Roll forming: Roll forming is a process by which a metal strip is progressively bent as it es through a series of forming rolls. 2.4 STAGES OF SHEARING OR SHEARING THEORY Shearing is a method of punching sheets without forming chips. The force for shearing is applied by the shearing blades.

2.4.1 Plastic Deformation Figure 2.1 Plastic Deformation The force applied by the punch on the stock material deforms it into the die opening. When the plastic limit of the stock material is exceeded by further application of force, the material is forced in to the die opening in the form of an embossed pad. A corresponding depression is formed on the upper face. This stage imparts a radius on the upper edge of the opening in the strip and on the lower edge of the punched out material.

2.4.2 Penetration

Figure 2.2 Penetration As the load is further increased, the punch will penetrate into the material to a certain depth. An equally thick portion of the material is forced into the die. This imparts a bright polished finish (cut band) on both the strip and the blank.

2.4.3 Fracture Figure 2.3 Fracture In this stage, fracture starts from both upper and lower punching edges. As the punch travels further, these fractures will extend towards each other and meet to cause complete separation. 2.5 PRESSES 2.5.1 Mechanical Press

The ram is actuated using a flywheel. Stroke motion is not uniform. 1. High forces at bottom of stroke 2. Suited to punching and punching 2.5.2 Hydraulic Press Longer strokes than mechanical presses, and develop full force throughout the stroke.Stroke motion is of uniform speed, especially adapted to deep drawing operations. 1. Longer ram stroke than mechanical types 2. Suited to deep drawing 3. Slower than mechanical drives

DRAWING FOR PUNCHING MACHINE

SHEET METAL: Sheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material. There are many different metals that can be made into sheet metal, such as: Aluminum, brass, copper, steel, tin, nickel and titanium. Sheet metal has applications in car bodies, airplane wings, medical tables, roofs for building and many other things.

Sheet metal is essentially metal pressed into sheets. These sheets are used at various places. These sheets can be bending, cut and molded into any shape for use anywhere. There is no count of places where these sheets are used. A sheet thin in of millimeters can be called foil where as 6mm (or) (0.25) onwards can be called a plate. Metal in the form of sheets is generally created by pressing a block of metal with great force. This process is called rolling. The higher the gauge, the thinner the metal is. There are many different metals that can be made into sheet metal. Aluminum, brass, copper, cold rolled steel, mild steel, tin, nickel and titanium are just a few examples of metal that can be made into sheets. The metals in this form have applications in car bodies, airplane wings, medical tables, roofs for building and many other things. A main feature of sheet metal is its ability to be formed and shaped by a variety of processes. Each process does something different to the metal giving it a different shape or size.

STRETCHING: Stretching is a process where sheet metal is clamped around its edges and stretched over a die or form block. This process is mainly used for the manufacture of aircraft wings, automotive door and window s. Stretching tools are very useful such as a kindilan.

DRAWING: Drawing forms sheet metal into cylindrical or box shaped parts by using a punch which presses the blank into a die cavity. Drawing process can also be utilized to create arbitrary shapes with the help of soft punch.

DEEP DRAWING: Deep Drawing is a type of drawing process where the depth of the part is more than half its diameter. Deep drawing is used for making automotive fuel tanks, kitchen sinks, 2 piece aluminum cans, etc. Deep drawing is generally done in multiple steps called draw reductions. The greater the depth, the increased number of reductions required. Deep drawing may also be accomplished with fewer reductions by heating the work piece.

CUTTING: Cutting sheet metal can be done in various ways from hand tools called tin snips up to very large powered shears. The metal is heated and then burnt by the laser beam, cutting the metal sheet. The quality of the edge can be mirror smooth, and a precision of around 0.1mm can be obtained.

BENDING AND FLANGING: Bending and flanging imparts stiffness to a sheet metal part or to form various shapes, such as 3 piece aluminum cans. Bending (metalworking) just form something in a form of a pipe.

PUNCHING AND SHEARING: During punching or shearing, the sheet metal is cut by using a punch and die. This process can allow many different shapes and patterns, punch machine.

SPINNING: Spinning is used to make axis-symmetric parts by applying a work piece to a rotating mandrel with the help of rollers or rigid tools. Spinning is used to make rocket motor casings and missile nose cones and satellite dishes for example.

PRESS BRAKE FORMING: This is a form of bending, used for long and thin sheet metal parts. The machine that bends the metal is called a press brake. The lower part of the press contains a V shaped groove. This is called the die. The upper part of the press contains a punch that will press the sheet metal down into the v shaped die, causing it to bend.

There are several techniques used here, but the most common modern method is "air bending". The radius of the upper tool, but by the lower die width. Typically, the inner radius is equal to 1/6th of the V width used in the forming process. The press usually has some sort of back gauge to position depth of the bend along the work piece. The back gauge can be computer controlled to allow the operator to make a series of bends in a component to a high degree of accuracy. Simple machines control only the backstop, more advanced machines control the position and angle of the stop, its height and the position of the two reference pegs used to locate the material. The machine can also record the exact position and pressure required for each bending operation to allow the operator to achieve a perfect 90 degree bend across a variety of operations on the part.

ROLL FORMING: A continuous bending operation for producing open profiles or welded tubes with long lengths or in large quantities, Roll forming

SPUR GEAR A gear or cogwheel is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part to transmit torque. Geared devices can change the speed, torque, and direction of a power source. Gears almost always produce a change in torque, creating a mechanical advantage, through their gear ratio, and thus may be considered a simple machine. The teeth on the two meshing gears all have the same shape. [1] Two or more meshing gears, working in a sequence, are called a gear train or a transmission. A gear can

mesh with a linear toothed part, called a rack, thereby producing translation instead of rotation. The gears in a transmission are analogous to the wheels in a crossed, belt pulley system. An advantage of gears is that the teeth of a gear prevent slippage. When two gears mesh, if one gear is bigger than the other, a mechanical advantage is produced, with the rotational speeds, and the torques, of the two gears differing in proportion to their diameters. In transmissions with multiple gear ratios—such as bicycles, motorcycles, and cars—the term "gear" as in "first gear" refers to a gear ratio rather than an actual physical gear. The term describes similar devices, even when the gear ratio is continuous rather than discrete, or when the device does not actually contain gears. Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk with teeth projecting radially. Though the teeth are not straight-sided (but usually of special form to achieve a constant drive ratio, mainly involute but less commonly cycloidal), the edge of each tooth is straight and aligned parallel to the axis of rotation. These gears mesh together correctly only if fitted to parallel shafts.[8] No axial thrust is created by the tooth loads. Spur gears are excellent at moderate speeds but tend to be noisy at high speeds In some machines (e.g., automobiles) it is necessary to alter the gear ratio to suit the task, a process known as gear shifting or changing gear. There are several ways of shifting gears, for example: 

Manual transmission



Automatic transmission



Derailleur gears, which are actually sprockets in combination with a roller chain



Hub gears (also called epicyclic gearing or sun-and-planet gears)

There are several outcomes of gear shifting in motor vehicles. In the case of vehicle noise emissions, there are higher sound levels emitted when the vehicle is engaged in lower gears.

The design life of the lower ratio gears is shorter, so cheaper gears may be used, which tend to generate more noise due to smaller overlap ratio and a lower mesh stiffness etc. than the helical gears used for the high ratios. This fact has been used to analyze vehicle-generated sound since the late 1960s, and has been incorporated into the simulation of urban roadway noise and corresponding design of urban noise barriers along roadways.

DESIGN DRAWINGS 4.1 CHILD PARTS AND FUNCTION The punching tool consists of following major parts and their functions are stated below. 4.1.1 Top Plate The punch assembly consisting of punch, punch holder and thrust plate is mounted on the top plate with screws and dowels. Shank also screwed to top plate. 4.1.2 Bottom Plate Bottom plate is the base of the tool. The die and guide pillars are fitted to this plate. It provides cushioning effect to the die. It employs an opening at bottom to collect the output blanked part. 4.1.3 Punching Die Plate Die is one of important punching tool in the punching tool. The size or contour of the die opening will be same as the dimension of the desired output component. 4.1.4 Punching Punch Punch is the other important punching tool in the punching tool. A force is exerted on the punch by the press to punch the strip placed on the die. The size of the punch will be smaller than the dimension of the desired component. It will penetrate into die for minimum of 3 to 5mm. 4.1.5 Stripper Plate

After punching operation when punch is withdrawn back, the blanked part adhere (Stick on) to punch surface. To facilitate removal of part from punch, stripper used. Also it used for guiding punch and to hold the strip flat during punching operation. 4.1.6 Thrust Plate While punching the strip, the punch exerts an upward thrust. To prevent that thrust being transmitted to top plate, a thrust or back plate is provided behind the punch. Otherwise it will damage the top plate. 4.1.7 Punch Holder It is a plate used to hold the punch in position without any transition. Punch holder provides a rigid to the punch during punching. 4.1.8 Guide Bush and Pillar Guide pillar and bushes are used to align the top and bottom plate. They keep the complete alignment of tool during entire operation. 4.1.9 Shank Shank is a connector between tool and the press ram. It is screwed to the top plate firmly. FABRICATION The fabrication of each part of the punching tool was almost carried out in conventional machines such as lathe, vertical milling machine, surface grinder, etc. The process planning for individual parts have been discussed below. 5.1.1 General Process Flow 1. Choosing Raw material 2. Sizing the edges to desired dimension in surface grinder 3. Marking and punching the coordinates points 4. Drilling and Counter Drilling in vertical milling machine 5. Slot opening in EDM wire cut or vertical milling machine 6. Filing slot surface and edges 7. Tapping using tap wrench 8. Top and bottom surface grinding 9. Chamfering the edges 5.1.2 Top Plate  The raw material dimension of (Mild Steel) plate 170 x 100 mm is taken  Edges were grinded in a surface grinder

 Marking and punching done to get coordinates for hole centers as per the drawing  Holes of Ø22x2 Nos., Ø19 and Ø6.6x6 Nos were drilled in vertical milling machine  Counter boring done for Ø11x4 Nos  Top and bottom surfaces were grinded  Chamfering of 2x45° done at all corners 25 5.1.3 Bottom Plate  The raw material dimension of (Mild Steel) plate 170 x 100 mm is taken  Edges were grinded in a surface grinder  Marking and punching done to get coordinates for hole centers as per the drawing  Holes of Ø16x2 Nos and Ø6.6x6 Nos were drilled in vertical milling machine  Counter boring done for Ø11x4 Nos  Slot were cut in vertical milling machine  Filing done on the slot surfaces and edges  Top and bottom surfaces were grinded  Chamfering of 2x45° done at all corners 5.1.4 Punching Die Plate  The raw material dimension of (HCHCR) plate 100 x 100 mm is taken  Edges were grinded in a surface grinder  Marking and punching done to get coordinates for hole centers as per the drawing  Holes of Ø6.6x4 Nos and Ø6x2 Nos were drilled in vertical milling machine  Slot were cut in EDM wire cut process  Top and bottom surfaces were grinded  Chamfering of 2x45° done at all corners 5.1.5 Punching Punch  The raw material dimension of (HCHCR) plate 75 x 75 x 30 mm is taken  Slot profile were cut in EDM wire cut process  Marking and punching done to get coordinates for hole centers as per the drawing 26

 Holes of Ø4.7x2 Nos were drilled in vertical milling machine  Tapping done for M5x2 Nos  Top and bottom surfaces were grinded 5.1.6 Stripper Plate  The raw material dimension of (Mild Steel) plate 100 x 100 mm is taken  Edges were grinded in a surface grinder  Marking and punching done to get coordinates for hole centers as per the drawing  Holes of Ø5.5x4 Nos and Ø6x2 Nos were drilled in vertical milling machine  Tapping done for M6x4 Nos  Slot were cut in vertical milling machine  Filing done on the slot surfaces and edges  Strip feed channel cut in vertical milling machine  Top and bottom surfaces were grinded  Chamfering of 2x45° done at all corners 5.1.7 Thrust Plate  The raw material dimension of (Mild Steel) plate 100 x 100 mm is taken  Edges were grinded in a surface grinder  Marking and punching done to get coordinates for hole centers as per the drawing  Holes of Ø6.6x6, Ø5.5x2 Nos were drilled in vertical milling machine  Counter sinking done for M5x2 Nos  Top and bottom surfaces were grinded  Chamfering of 1x45° done at all corners 27 5.1.8 Punch Holder  The raw material dimension of (Mild Steel) plate 100 x 100 mm is taken  Edges were grinded in a surface grinder  Marking and punching done to get coordinates for hole centers as per the drawing  Holes of Ø5.5x4 Nos and Ø6x2 Nos were drilled in vertical milling machine  Tapping done for M6x4 Nos  Slot were cut in vertical milling machine  Filing done on the slot surfaces and edges

 Top and bottom surfaces were grinded  Chamfering of 2x45° done at all corners 5.1.9 Guide Bush  The raw material dimension of (Mild Steel) bar Ø32 x 30 mm is taken  Facing and step turning done to reduce Ø16 x 10 mm and Ø22 x 14.5 mm  Drilling and boring done for Ø16  Chamfering of 1x45° done at both ends 5.1.10 Guide Pillar  The raw material dimension of (Mild Steel) bar Ø24 x 125 mm is taken  Facing and turning done to reduce to Ø16 x 120 mm  Chamfering of 1x45° done at both ends 28 5.2 ASSEMBLY Assembling the fabricated parts plays vital role in order to accomplish the punching tool. In Punching tool we can split into sub-assembly. One is top assembly and other is bottom assembly. 5.2.1 Top Assembly Top assembly comprises of top plate, thrust plate, punch holder, punch, guide bush and shank. Punch screwed to the punch holder, subsequently punch holder and thrust plate screwed to top plate. Guide bush is inserted into top plate in tight fit. 5.2.2 Bottom Assembly Bottom assembly comprises of bottom plate, die plate, stripper plate and guide pillar. Die plate and stripper plate screwed to bottom plate, while guide pillar inserted into bottom plate in tight fit. 29 5.2.3 Final Assembly Finally, both top and bottom assemblies are aligned together to accomplish the punching tool assembly.

LIST OF MATERIALS FACTORS DETERMINING THE CHOICE OF MATERIALS

The various factors which determine the choice of material are discussed below.

1. Properties: The material selected must posses the necessary properties for the proposed application. The various requirements to be satisfied Can be weight, surface finish, rigidity, ability to withstand environmental attack from chemicals, service life, reliability etc. The following four types of principle properties of materials decisively affect their

selection

a. Physical b. Mechanical c. From manufacturing point of view d. Chemical The various physical properties concerned are melting point, thermal Conductivity, specific heat, coefficient of thermal expansion, specific gravity, electrical conductivity, magnetic purposes etc. The

various

tensile,Compressive

Mechanical shear,

properties

bending,

Concerned

torsional

and

are

buckling

strength load,

in

fatigue

resistance, impact resistance, eleastic limit, endurance limit, and modulus of elasticity, hardness, wear resistance and sliding properties.

The various properties concerned from the manufacturing point of view are,  Cast ability  Weld ability

 Forge ability  Surface properties  Shrinkage  Deep drawing etc.

2. Manufacturing case: Sometimes the demand for lowest possible manufacturing cost or surface qualities obtainable by the application of suitable coating substances may demand the use of special materials.

3. Quality Required: This generally affects the manufacturing process and ultimately the material. For example, it would never be desirable to go casting of a less number of components which can be fabricated much more economically by welding or hand forging the steel.

4. Availability of Material: Some materials may be scarce or in short supply. It then becomes obligatory for the designer to use some other material which though may not be a perfect substitute for the material designed. the delivery of materials and the delivery date of product should also be kept in mind.

5. Space consideration: Sometimes high strength materials have to be selected because the forces involved are high and space limitations are there.

6. Cost:

As in any other problem, in selection of material the cost of material plays an important part and should not be ignored. Some

times

factors

like

scrap

utilization,

appearance,

and

non-

maintenance of the designed part are involved in the selection of proper materials.

S.No

DESCIRPTION 1

Double acting pneumatic

QTY

Material

1

aluminum

cylinder 2

Solenoid Valve

1

aluminum

3

Flow control valve

1

aluminum

4

Moving & fixed cutter

1+1

M.S

5

Control unit

1

Electronic

6

PU tubes

5meter

polyurethane

7

Base

1

M.S

8

Base up plate

1

M.S

9

Center plate

1

M.S

CHAPTER-X

COST ESTIMATION 1. MATERIAL COST: S.No

DESCRIPTION

QTY

MATERIAL

AMOUNT (Rs)

1

Spur Gear

1

aluminum

1500

2

Frame

1

Aluminum

550

3

Die

1

Aluminum

475

4

Moving jaw & fixed jaw

1+1

M.S

665

5

Control unit

1

Electronic

650

6

Rod

5 meter

Polyurethane

400

7

Base

1

M.S

655

8

Base up plate

1

M.S

355

9

Center plate

1

M.S

215

Total

2. LABOUR COST:

5465

Lathe, drilling, welding, drinding, power hacksaw, gas cutting cost

3. OVERGHEAD CHARGES: The overhead charges are arrived by”manufacturing cost” Manufaturing Cost

=

Material Cost +Labour Cost

=

Overhead Charges =

5465 + 1200 =

6665

=

20%of the manufacturing cost

1333

4. TOTAL COST: Total cost = Material Cost +Labour Cost +Overhead Charges =5465 + 1200 + 1333 =7998 Total cost for this project

= 8000

WORKING PRINCIPLE

Here we fabricated the punching machine. It consist of rack, pinion, handle, bearing, punching tool and main frame. The punching tool is fixed at the bottom of rack. Then the

pinion is mate with the rack and it is fixed by using the bearings. The handle is coupled with the pinion when the press the handle the tool moves up and down motions. Due to up and down motion the punching operation is held.

MERITS:



More efficient



Time consumption is less



Quick process



Avoid wastage of electricity.

DEMERITS:

Manually operated



APPLICATION

APPLICATIONS 

It can be used in all sheet fabricating industries.

CONCLUSION Thus a prototype punching tool is fabricated and its functions have been demonstrated and explained. The tool could be utilised in mass production to produce identical parts with good geometrical tolerances. By choosing appropriate tool steels for die, punch and other parts, the tool life could increased for maximum range. It has the capacity to blank the sheet up to the thickness of 0.5mm of mild steel, aluminium and zinc, etc.

REFERENCES 1. “Tool & Die Maker 2nd Year: Press Tools, Jigs & Fixtures” CIMI (Central Instructional Media Institute), Guindy. 2. “Tool & Die Maker 3rd Year: Press Tools, Jigs & Fixtures” CIMI (Central Instructional Media Institute), Guindy. 3. S.K. Hajra Choudhury, A.K. Hajra Choudhury and Nirjhar Roy, (2005) “Elements of Workshop Technology” Machine Tools Vol.2, 11th Edition.