Blanking or Stamping or Punching of Sheet Metal Project Report (Punch and Die)

DESIGN AND FABRICATION OF A BLANKING TOOL A PROJECT REPORT

Submitted by

GOPI KRISHNAN. C

[30408114309]

VAIBHAV VASAN. M. S

[30408114092]

in partial fulfillment for the award of the degree of

BACHELOR OF ENGINEERING IN

MECHANICAL ENGINNERING

EASWARI ENGINNEERING COLLEGE, CHENNAI – 600 089

ANNA UNIVERSITY : CHENNAI 600 025 APRIL - 2011

ANNA UNIVERSITY : CHENNAI 600 025

BONAFIDE CERTIFICATE

Certified

that

this

design

and

fabrication

project

report

“DESIGN AND FABRICATION OF A BLANKING TOOL” is the bonafide work of “ GOPI KRISHNAN. C and VAIBHAV VASAN. M. S ” who carried out the project work under my supervision.

SIGNATURE

SIGNATURE

DR.V. ELANGO, ME, PhD

MR. M. SENTHIL KUMAR, ME

PROFESSOR AND HEAD

SUPERVISOR

Department of Mechanical Engineering

Assistant Professor (Sl. Gr)

Easwari Engineering College

Department of Mechanical Engineering

Ramapuram, Chennai – 89

Easwari Engineering college Ramapuram, Chennai - 89

INTERNAL EXAMINER

EXTERNAL EXAMINER

ACKNOWLEDGEMENT

We take the opportunity to acknowledge the assistance and contribution of the people towards our successful project completion.

We would like to thank the Management of our college, the Director and our beloved principal, Dr. K. ABDHUL GHANI, PhD, for all his support and words of wisdom.

We sincerely thank Dr. V. ELANGO, PhD, Professor and Head, Department of Mechanical Engineering for encouraging us during the course of this project.

We would like to thank and acknowledge our Project Guide, Coordinator and Class counselor, Mr. M. SENTHIL KUMAR, ME, Assistant Professor (Sl. Gr) for motivation and guiding throughout the project.

We also thank our Class coordinator, Mr. D. BALAJEE, ME, Assistant Professor for helping us towards the project.

We express our gratitude to all the teaching and non-teaching staffs, members of workshop, our class friends and our parents for their invaluable cooperation towards the project.

ABSTRACT

Press tools are tools, used to produce a particular component in large quantity, out of sheet metals by using presses.

The different types of press tool operations are blanking, piercing, forming, drawing, cutting off, parting off, embossing, coining, extrusion, perforating, trimming, notching, shaving, lancing, dinking, broaching, curling, bulging, swaging, flaring, etc.

Blanking is a process of producing flat components. The entire periphery is cut. The cut-out piece is called blank. This process is called blanking and tool used is called as blanking tool.

For producing any sheet metal components, blanking operation is the primary process to carry-out. In this project, a real time design of a blanking tool and fabrication of a prototype working model is presented.

iv

TABLE OF CONTENTS CHAPTER NO.

TITLE

PAGE NO.

ABSTRACT

iv

LIST OF TABLE

ix

LIST OF FIGURES

x

LIST OF SYMBOLS

xii

1

INTRODUCTION

01

2

LITERATURE REVIEW

02

2.1

INTRODUCTION

02

2.2

SHEET PROCESSING

02

2.3

SHEETMETAL PROCESSES

02

2.3.1 Shearing Process

03

2.3.2 Forming Process

03

SHEARING THEORY

03

2.4.1 Plastic Deformation

04

2.4

v

2.5

3

4

2.4.2 Penetration

04

2.4.3 Fracture

05

PRESSES

05

2.5.1 Mechanical Press

05

2.5.2 Hydraulic Press

05

DESIGN CALCULATIONS

07

3.1

BLANKING FORCE CALCULATION

07

3.2

PRESS CAPACITY

07

3.3

DIE OPENING DIMENSIONS

08

3.4

PUNCH DIMENSIONS

08

DESIGN DRAWINGS

09

4.1

CHILD PARTS AND FUNCTION

09

4.1.1 Top Plate

09

4.1.2 Bottom Plate

09

4.1.3 Blanking Die Plate

09

4.1.4 Blanking Punch

09

vi

5

4.1.5 Stripper Plate

10

4.1.6 Thrust Plate

10

4.1.7 Punch Holder

10

4.1.8 Guide Bush and Pillar

10

4.1.9 Shank

10

FABRICATION AND ASSEMBLY

24

5.1

FABRICATION

24

5.1.1 General Process Flow

24

5.1.2 Top Plate

24

5.1.3 Bottom Plate

25

5.1.4 Blanking Die Plate

25

5.1.5 Blanking Punch

25

5.1.6 Stripper Plate

26

5.1.7 Thrust Plate

26

5.1.8 Punch Holder

27

5.1.9 Guide Bush

27

vii

5.2

6

7

5.1.10 Guide Pillar

27

ASSEMBLY

28

5.2.1 Top Assembly

28

5.2.2 Bottom Assembly

28

5.2.3 Final Assembly

29

RESULT AND DISCUSSION

30

6.1

MATERIAL

30

6.2

MACHINING

30

6.3

ALIGNMENT

30

CONCLUSION

31

REFERENCES

32

viii

LIST OF TABLES TABLE NO.

4.1

DESCRIPTION

BILL OF MATERIALS

ix

PAGE NO.

23

LIST OF FIGURES FIGURE NO.

DESCRIPTION

PAGE NO.

2.1

PLASTIC DEFORMATION

04

2.2

PENETRATION

04

2.3

FRACTURE

05

2.4

MECHANICAL PRESS

06

2.5

HYDRAULIC PRESS

06

4.1

FINISHED BLANK COMPONENT

11

4.2

BLANKING TOOL PART: TOP PLATE

12

4.3

BLANKING TOOL PART: BOTTOM PLATE

13

4.4

BLANKING TOOL PART: BLANKING DIE PLATE

14

4.5

BLANKING TOOL PART: BLANKING PUNCH

15

4.6

BLANKING TOOL PART: STRIPPER PLATE

16

4.7

BLANKING TOOL PART: THRUST PLATE

17

4.8

BLANKING TOOL PART: PUNCH HOLDER

18

4.9

BLANKING TOOL PART: GUIDE BUSH x

19

4.10

BLANKING TOOL PART: GUIDE PILLAR

20

4.11

BLANKING TOOL CATIA 3D ASSEMBLY

21

4.12

BLANKING TOOL CATIA 2D ASSEMBLY

22

5.1

FABRICATED BLANKING TOOL ASSEMBLY

29

xi

LIST OF SYMBOLS SYMBOLS

DESCRIPTION

C

-

CONSTANT

CSK

-

COUNTER SUNK

EDM

-

ELECTRIC DISCHARGE MACHINING

F

-

BLANKING FORCE

Fus

-

ULTIMATE SHEAR STRENGTH OF MATERIAL

HCHCR

-

HIGH CARBON HIGH CHROMIUM STEEL

M

-

METRIC

MS

-

MILD STEEL

N

-

NEWTON (UNIT)

p

-

PERIMETER

R

-

RADIUS

t

-

THICKNESS OF SHEET

Ø

-

DIAMETER

xii

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 cutting and forming operations of sheet metal. 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 1

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

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. Blanking:

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 passes through a series of forming rolls.

2.4 STAGES OF SHEARING OR SHEARING THEORY Shearing is a method of cutting sheets without forming chips. The force for shearing is applied by the shearing blades.

3

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. 4

2.4.3 Fracture

Figure 2.3 Fracture In this stage, fracture starts from both upper and lower cutting 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 blanking 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

5

Figure 2.4 Mechanical Press

Figure 2.5 Hydraulic Press 6

CHAPTER 3 DESIGN CALCULATIONS

3.1 BLANKING FORCE CALCULATION The blanking force or cutting force is the force required to punch a blank. This determines the capacity of the press to be used for the tool. F = p x t x fus Where, F – Blanking force (N) p – Perimeter (mm) t – Thickness of sheet (mm) Fus – Ultimate shear strength of sheet (N/mm2) F = 130 x 0.5 x 300

Blanking Force, F = 19500 N

3.2 PRESS CAPACITY The rated capacity of press is the force which the slide or ram will exert near the bottom of the stroke. Capacity = 1.1 of Blanking force (10% more than blanking force) Where, Blank force = 19500 N Capacity = 1.1 x 19500 = 21500 N Capacity = 21500 / (9.81 x 1000) = 2.2 ton

Press Capacity (Tonnage) = 2.2 Ton 7

3.3 DIE OPENING DIMENSIONS Die is one of the cutting elements of a blanking tool. It admits the punch to enter in for cutting action. For blanking process, die dimensions are same as the output component.

Slot Length

= 50 mm

Slot Width

= 25 mm (Radius 12.5mm)

3.4 PUNCH DIMENSIONS Punch is the other cutting element of a blanking tool. It exerts a force on the strip material placed on the die to punch the desired contour.

Length

= (Dimension – 2 x clearance)

Width

= (Dimension – 2 x clearance)

Clearance = C x t x √ (Fus/10) [C = constant 0.01, t = thick of sheet, fus = shear strength of sheet]

Length

= (50 – 2 x 0.01 x 0.5 x √300/10) = 49.94 mm

Width

= (25 – 2 x 0.01 x 0.5 x √300/10) = 24.94 mm

Punch Length

= 49.94 mm

Punch Width

= 24.94 mm

8

CHAPTER 4 DESIGN DRAWINGS

4.1 CHILD PARTS AND FUNCTION The blanking 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 Blanking Die Plate Die is one of important cutting tool in the blanking tool. The size or contour of the die opening will be same as the dimension of the desired output component.

4.1.4 Blanking Punch Punch is the other important cutting tool in the blanking 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.

9

4.1.5 Stripper Plate After blanking 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 support 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. The individual part drawings with dimensions are followed. All dimensions are in “mm” Tolerances Length: ± 0.1mm Diameter: ± 0.05mm 10

Figure 4.1 Finished Blank Component 11

Figure 4.2 Blanking Tool Part: Top Plate 12

Figure 4.3 Blanking Tool Part: Bottom Plate 13

Figure 4.4 Blanking Tool Part: Blanking Die Plate 14

Figure 4.5 Blanking Tool Part: Blanking Punch 15

Figure 4.6 Blanking Tool Part: Stripper Plate 16

Figure 4.7 Blanking Tool Part: Thrust Plate 17

Figure 4.8 Blanking Tool Part: Punch Holder 18

Figure 4.9 Blanking Tool Part: Guide Bush 19

Figure 4.10 Blanking Tool Part: Guide Pillar 20

Figure 4.11 Blanking Tool CATIA 3D Assembly 21

Figure 4.12 Blanking Tool CATIA 2D Assembly 22

Table 4.1 Blanking Tool Assembly: Bill of Materials PART NO.

DESCRIPTION

MATERIAL

NO. OFF

1

BOTTOM PLATE

MILD STEEL

1

2

BLANKING DIE PLATE

HCHCR

1

3

STRIPPER PLATE

MILD STEEL

1

4

BLANKING PUNCH

HCHCR

1

5

PUNCH HOLDER

MILD STEEL

1

6

THRUST PLATE

MILD STEEL

1

7

TOP PLATE

MILD STEEL

1

8

GUIDE PILLAR

MILD STEEL

2

9

GUIDE BUSH

MILD STEEL

2

10

SHANK

MILD STEEL

11

SCREWS

STD 23

1

--

CHAPTER 5 FABRICATION AND ASSEMBLY 5.1 FABRICATION The fabrication of each part of the blanking 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 24

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 Blanking 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 Blanking 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 25

 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

26

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

27

5.2 ASSEMBLY Assembling the fabricated parts plays vital role in order to accomplish the blanking tool. In Blanking 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.

28

5.2.3 Final Assembly Finally, both top and bottom assemblies are aligned together to accomplish the blanking tool assembly.

Figure 5.1 Fabricated Blanking Tool Assembly

29

CHAPTER 6 RESULT AND DISCUSSION The machining and fabrication plays a critical role in the project, since all the individual parts has employed machining. Those significant points are discussed below.

6.1 MATERIAL Mild steel have been used for majority of the parts, since it is ductile and can be easily machined. Moreover it is economical. Exclusively for die and punch we have employed HCHCR (High Carbon High Chromium) steel. It is done since the punch and die are the cutting members in the tool, they have to withstand cutting force and resist wear. Even the die and punch could be hardened and tempered for effective purpose.

6.2 MACHINING Majority of conventional machines has been used for machining. Especially for obtaining excellent corners and radius in punch and die we has outsourced for EDM WIRE-CUT process. The conventional machines like lathe, vertical milling machine, vertical drilling machine, tapping have been used for machining the tool.

6.3 ALIGNMENT Lot of care has been taken for the alignment of the tool. The punch and die seems to be the heart of the tool, but the die set consisting of top plate, bottom plate, guide pillar and bush stood more critical during machining and assembly. Since the top plate has to travel longitudinally in the guide pillar placed in bottom plate. If these is not achieved the entire process will be in vain. So lot of care has been taken for its alignment. 30

CHAPTER 7 CONCLUSION Thus a prototype blanking 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.

Our tool could be used in presses for medium production quantity of 8,000 to 12,000 units. By using the high grade die sets quantity can be increased over 25,000 units.

31

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.

32