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.

iv

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.

v

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

2.4 SHEARING THEORY 03

2.4.1 Plastic Deformation 04

vi

2.4.2 Penetration 04

2.4.3 Fracture 05

2.5 PRESSES 05

2.5.1 Mechanical Press 05

2.5.2 Hydraulic Press 05

3 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

4 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

vii

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

5 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

viii

5.1.10 Guide Pillar 27

5.2 ASSEMBLY 28

5.2.1 Top Assembly 28

5.2.2 Bottom Assembly 28

5.2.3 Final Assembly 29

6 RESULT AND DISCUSSION 30

6.1 MATERIAL 30

6.2 MACHINING 30

6.3 ALIGNMENT 30

7 CONCLUSION 31

REFERENCES 32

ix

LIST OF TABLES TABLE NO. DESCRIPTION PAGE NO.

4.1 BILL OF MATERIALS 23

x

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 19

xi

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

xii

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

1

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

2

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.

3

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.

4

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.

5

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

6

Figure 2.4 Mechanical Press

Figure 2.5 Hydraulic Press

7

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

8

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

9

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.

10

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

11

Figure 4.1 Finished Blank Component

12

Figure 4.2 Blanking Tool Part: Top Plate

13

Figure 4.3 Blanking Tool Part: Bottom Plate

14

Figure 4.4 Blanking Tool Part: Blanking Die Plate

15

Figure 4.5 Blanking Tool Part: Blanking Punch

16

Figure 4.6 Blanking Tool Part: Stripper Plate

17

Figure 4.7 Blanking Tool Part: Thrust Plate

18

Figure 4.8 Blanking Tool Part: Punch Holder

19

Figure 4.9 Blanking Tool Part: Guide Bush

20

Figure 4.10 Blanking Tool Part: Guide Pillar

21

Figure 4.11 Blanking Tool CATIA 3D Assembly

22

Figure 4.12 Blanking Tool CATIA 2D Assembly

23

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 1

11 SCREWS STD --

24

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

25

5.1.3 Bottom Plate The raw material dimension of (Mild Steel) plate 170 x 100 mm is taken



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



5.1.4 Blanking Die Plate The raw material dimension of (HCHCR) plate 100 x 100 mm is taken



drawing

Holes of Ø6.6x4 Nos and Ø6x2 Nos were drilled in vertical milling machine

Slot were cut in EDM wire cut process


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


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



drawing





Strip feed channel cut in vertical milling machine


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



drawing

Holes of Ø6.6x6, Ø5.5x2 Nos were drilled in vertical milling machine

Counter sinking done for M5x2 Nos



27

5.1.8 Punch Holder The raw material dimension of (Mild Steel) plate 100 x 100 mm is taken



drawing







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

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.

29

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

30

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.

31

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.

32

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.

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

Documents

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