Design and Optimization

ABSTRACT

Design and development of Progressive tools for the sheet metal component is one

important phase in sheet metal manufacturing. Sheet metal press working process by

progressive tools is a highly complex process that is vulnerable to various uncertainties such

as variation in progressive tools geometry, strip layout, die shear, material properties,

component and press working equipment position error and process parameters related to its

manufacturer. These uncertainties in combinations can induce heavy manufacturing losses

through premature die failure, final part geometric distortion and production risk.

Identification of these uncertainties and quantifying them will facilitate a risk free

manufacturing environment, which goes a long way to minimize the over all cost of

production. FEM based modeling of press working process is a very effective tool to over

come the above uncertainties.

Over recent years vigorous developments have been undertaken to enable the

production of sheet metal components (electrical insert) by press working. The driving force

behind this activity has been values addition obtainable by this method in comparison with

others. These developments are leading to the commercial feasibility of producing sheet metal

component (electrical insert) forms of high quality, ready for use.

In this project work progressive tool design has been examined using CAD package

(Solid works-2003) and analyzed by FEM. From software and conventional results, the

dimensions and materials can be optimized, which is cost effective.

CHAPTER 1

INTRODUCTION

The progressive die performs a series of fundamental sheet metal working at two or

more stages during the press running to produce a production part as the strip stock moving

through the die surface. Press working from the optimum dies design and its making has been

the purpose of mass production in the manufacturing field.

The design and manufacture of press tools, or punches and dies, is a branch of

production technology that has extended into many lines of engineering manufacture over the

past seventy years. There is no doubt that the accuracy achieved by new ideas in design and

construction applied by the press tool designer, coupled with increased speed and rigidity of

the presses etc, used, have all contributed toward maintaining this form of metal tooling well

to the force as a means of obtaining pleasing, yet strong, durable articles that can withstand

severe day-to-day usage.

The modern car, radio and television sets, clocks and watches, house hold wares and

office furniture are all examples where press tools are used in varying degrees permitting the

marketing of a complete series of products quickly and cheaply to bring them within the

purchasing power of the public.

More and more it has become the practice to produce from sheet metal by some form

of pressing process, work pieces that would have been made from bar, forging or casting two

or three decades ago. Also, the handling of both strip material and semi-finished components

has assumed an importance simply because fast and efficient movement means cheap products

from operators who do not suffer fatigue from the handling of awkward or heavy components.

However, it should not be forgotten that press design has made many advances in recent years

in common with, for example, the machine tool industry, and machines are now available that

are capable of withstanding the heavy stresses set up in many modern production process.

From this encouraging picture it may come something of a surprise to realize that in

press work there are often factors, particularly in bending and drawing process where

successful results are obtained only through the extensive experience of a tool designer and

not from information derived from text books. Four factors are essential contributions to first-

class press work.

1. Good operation planning

2. Excellent tool design

3. Accurate tool making

4. Knowledgeable press setting

So, this project needs a whole of press tool data, our field experiences, and theoretical

instructions. According to upper factors, this project could be achieved to the optimum die

design through the FE analysis, Solid works modeling, and practical method of die making.

Furthermore the aim of least defects could be obtained mostly by revision through the tryout.

1.1 COMPONENT ANALYSIS

Material : Mild Steel (St-42)

Thickness : 2 mm

Shear strength : 35kg/mm2

Temper grade : Hard

Supply condition : Strips

Geometry tolerance : IS2102

PROPERTIES

It has a bright and fine finish.

It can withstand heavy loads, as it is tough.

Welding of this material does not change its chemical structure.

It has a scale free material.

Fine or bright for electroplating.

1.2 SCOPE OF THE PROJECT

The scope of the project involves the design, modeling for assembly, FEM analysis,

detailed drawings for the sheet metal tools and 3D CAD Data for the manufacture of the

components mentioned below,

Electrical Insert (LG-Company component)

Modeling for assembly

All tool elements were modeled by solid works2003. This stage involved making the

drawings of assembly, individual tool elements etc.

FEM analysis

The main functional elements like punches, die, stripper plate, guide pillar, guide

bush, top half and bottom plate were analyzed by Ansys-V10.0

Preparing 3D models

The punch, die and shedder of certain tools needed to be CNC machined. For this 3D

models of the punch, die and shedders where made in solid works2003.

CHAPTER 2

LITERATURE REVIEW

2.1 CUTTING TOOLS

Cutting tools are used to cut the sheet metal to required blanks, or providing the holes

inside the components. And also trimming out the draw edges and formed components to

maintaining the finished size of the component. Here the important thing is that the distance or

the gap between the Punch and Die is calculated one according to the sheet thickness and shear

strength of the sheet. And also depends on the type of operation. In the shaving operation the

clearance is less as that of calculated for the general cutting clearance. These tools are mainly

divided as,

Progressive Tools

Combination Tools

Compound Tools

2.1.1 Progressive Tools

Progressive tool performs two or more operations at different stages in each stroke.

The stock strip is advanced through a series of stations that form one or more distinct press

working operations on the strip to get the component.

2.1.2 Combination Tools

A die in which cutting operation and non-cutting operations on a part is accomplished

in one stroke of the press. The cutting operations may be blanking, piercing, trimming and are

combined with non cutting operations which may include bending, forming, drawing and

embossing etc. The most common type of combination dies blanks and draws a part.

2.1.3 Compound Tools

Similar to a progressive tools, a compound tool also produce blanks having pierced

holes but the difference being that the former performance the operations at more than one

station where as the later performs both the operations simultaneously at the same time. The

conventional positions of the blanking punch and die are inverted. The blanking punch being

clamped to the die shoe forms part of the bottom tool. Where as, the blanking die being

clamped to the die head forms part of the top tool. The piercing punches assume the

conventional position and inside the blanking die opening piercing punches are mounted with

a punch holder. Their mating piercing dies are formed in the blanking punch.

The slug resulting from the piercing operation falls down through the die shoe opening

provided for the purpose. Note that the blanking die walls are straight through without an

angular clearance as the piece parts are knocked out of the die as soon as the blanking is over.

After completion of piece part the burr forms on the same side of the piece part.

2.2 SHEARING THEORY AND ACTION

Shearing is the method of cutting a sheet metal (shear out) without forming chips. The

material is stressed from punch and dies side simultaneously in sections that lies parallel to the

forces applied by means of shear blades or punches and die as shown in Fig.1.1.

The cutting action that occurs on blanking or piercing is that similar to that of chip

formation by a cutting tool. The punch contracts the work material supported by the die and a

pressure build up occurs. The shearing or cutting forces necessary to bring about shearing or

rapture of the material depend primarily upon the shearing strength of the material, thickness

and cutting length.

Three critical stages of shearing are

Plastic Deformation

Penetration

Fracture

The metal is subjected to both tensile and compressive stresses, stretching beyond the

elastic limit. Then the Plastic deformation, Penetration and Fracture will takes place.

Fig 2.3.1 Critical Stage Stress Diagram

2.3 CRITICAL STAGES

2.3.1 Plastic Deformation

The stock material has been placed on the die, the press has been tripped and the punch

is being driven toward the die. The punch contacts the stock material and exerts pressure on it.

When the elastic limit of the stock material is exceeded, plastic deformation takes place.

The stage imparts a radius (roll over) on the upper edge of the opening in the strip of

metal and the lower edge of the blanked or slug material as shown in the Fig.2.3.2

Fig 2.3.2 Plastic Deformation Stage Diagram2.3.2 Penetration

As the driving force of the ram continues, the punch is forced to penetrate the stock

material and the blank or slug is displaced into the die opening a corresponding amount. This

is the true shearing portion of the cutting cycle. As the further load increased the punch will

penetrate the material to a certain depth. And equally thick portion of the metal is forced into

the die. This imparts metal Bright polished finish (cut band) on both the strip metal and

blanked component or the slug. On the optimum cutting condition, the, the cut band is 1/3

times the sheet thickness. This operation is shown in below Fig.2.3.3

Fig 2.3.3 Penetration Stage Diagram

2.3.3 Fracture

Further continuation of the pressure then causes fractures to start at the cutting edges of

the punch and die. These are the points of greatest stress concentration. Under proper cutting

conditions the fractures extend towards each other and meet. The blank or slug is separated

from the stock material. The punch then enters the die opening, pushing the blank or slug

slightly below the die cutting edge. This operation is shown in below Fig.2.3.4

Fig 2.3.4 Fracture Stage Diagram

2.4 CUTTING CLEARANCE

Cutting clearance is a gap between a side of punch and the corresponding side of the

die opening on one side of the edge when the punch is entered into die opening. This is shown

in below Fig 2.4.1

Fig 2.4.1 Cutting Clearance Diagram

Proper cutting clearance between punch and die cutting edges adds the following

advantages

Helps to produce accurate components.

Increases the life of Press Tool.

Reduces the cutting forces.

2.4.1 Excessive Cutting Clearance

This clearance illustrates comparatively large space between punch and die cutting

edges. The edge radius becomes larger and does not blunt smoothly into the cut band, the cut

band becomes smaller, some times degenerating to a more line of demarcation between the

break and edge radius. Cutting clearance results in objectionable piece part correction. This is

shown below Fig 2.4.2

Fig 2.4.2 Excessive Cutting Clearance Diagram

2.4.2 Insufficient Cutting Clearance

When the cutting clearance is slightly too small the conditioned may be identified by

greater width and irregularity of the cut band. If however the proportional cutting clearance is

further decreased, the stock material may react by showing two or more cut bands.

Objectionable burrs may appear on the piece part if the cutting clearance is insufficient. The

operation is shown in Fig 2.4.3

In the case of excessive clearance the burrs results from dragging of the material with

insufficient clearance the burr is caused by compressive force.

The followings are the draw backs of insufficient cutting clearance as,

Excess cutting force is required to shear or to cut the sheet of metal.

Both punches and dies become blunt and they have to be ground after short run.

The burrs on the work piece become unavoidable.

Blunt cutting edges causes excessive radius (roll over) on the opposite work surface.

The sheared or fractured surfaces are rough.

Fig 2.4.3 Insufficient Cutting Clearance Diagram

2.4.3 Optimum Cutting Clearance

The blank or slug has been made under optimum cutting conditions. The edge radius is

the result of the initial plastic deformation, which occurred during the first stage of the shear

action.

The highly burnished band, it is resulting from the second stage (penetration) of the

shearing action. The width of the cut band is approximately one third of the sheet thickness.

The balance of the cut is the break, which result from the third stage of the shearing action.

This is shown in Fig 2.4.4

Fig 2.4.4 Optimum Cutting Clearance Diagram

Optimum cutting clearance is calculated by the given below formulae.

C/2 = 0.01 X (t) X √ (fs)

Where,

C = Cutting clearance in mm.

t = Sheet thickness in mm.

fs = Max. Shear strength of the sheet material in kg/mm2

2.4.4 Land

The inner walls of the die opening are not usually made straight through as the blanks

or slugs tend to get jammed inside. This may result in undue stress built up. This may lead to

the breakage punch and die.

To avoid such a situation the die walls are kept straight wall is called the land.

2.4.5 Angular Clearance

Angular clearance is a draft or taper applied to the side walls of a die opening in order

to relieving internal pressure of die opening as it pass through the die opening.

Land and the Angular clearance are shown in the Fig.2.4.5

Fig 2.4.5 Land and Angular Clearance Diagram

2.5 CUTTING FORCE

Cutting force is that force which has to act on the stock material in order to cut out the

blank or slug. This determines the capacity of the press to be used for the particular tool. OR

sometimes it may be defined as, separating or cutting of work material from the parent

material.

Therefore, Cutting force = K x L x S t2 /1000 Tons.

Where

L = length of the cutting edge in mm.

T = thickness of the stock material in mm.

S = Shear strength of the stock material in kg/mm2.

or, Cutting force = L x S x Tmax

Where, L = Length of the periphery to be cut in mm.

S = Stock thickness in mm.

Tmax = shear strength in N / mm2

The following are the importance of cutting force,

For any cutting die, the cutting-force requirement is the major factor used to select a

punch press of proper rating for the job. Because of this, the cutting force should be

determined before building the die.

2.5.1 Shear Strength of Materials

When a cutting punch is driven through the stock material, shear action takes place. The

punching force overcomes the shear resistance of the stock material. Because of this the shear

strength of the stock material must be known in order to calculate the cutting force.

2.5.2 Stripping Force

Reasonably accurate calculations of stripping force requirements can be made. However,

it is not usually practical to lay down general rules. There are so many variable factors

involved that an accurate calculation must be a highly specialized computation for a specific

job only. The following important factors which is affect stripping force,

Stock material - Materials, which have a high friction, value and materials, which tend

to cling, are more difficult to strip.

Condition of cutting edges - When the cutting edges are sharpness tripping effort is

required.

Surface condition of sidewall - A punch, which has a smooth finish on its side, walls

strips more easily than a punch, which is not as smooth.

Distance between punches - More effort is required to strip punches that are close

together.

Area of stock material to be stripped.

2.6 ADVANTAGES OF PROGRESSIVE TOOLS

There are numerous advantages of progressive tools in the modern mechanical

industries which are follows,

Mass production can be achieved in a short time.

No more secondary operations are required to finish the component, which can directly

bring in to use.

Sheet metal operations have now replaced many components, which were earlier cast

or machined.

Metal economy and the resultant reduction in weight and cost, high productivity, use

of unskilled labor and high degree of possible precision have rendered presswork

indispensable for much mass production.

Goods such as electronic appliances, steel furniture, utensils and automotives.

The entire top of a car can be finished to size from a single sheet metal. There is no

need for further machining as in case of castings or forging.

2.7 LIMITATIONS OF PROGRESSIVE TOOLS

With the numerous advantages some limitation are follows,

The process cannot be applicable for the plastic material like plastic forming etc.

The sheet metal operation is very difficult for brittle material.

Press tool is not affordable for batch production.

High skilled labors and designers required.

2.8 JOURNAL REVIEW

Seon-Bong Lee, Dong-Hwan Kim and Byung-Min Kim [1] were

presented ‘Development of optimal layout design system in multihole

blanking process’. In order to produce precision integrated circuit (IC) leadframe, it must

be done through try-error. IC leadframe needs the precision shape for good efficiency. The

blanking of sheet metal using progressive dies is an important process on production of

precision electronic machine parts. Especially, the main defect is lead shift of inner leads in

progressive blanking process. In this paper, FE simulation technique has been proposed to

predict the deformation behavior and springback of IC leadframe through the simulation of the

progressive blanking process. It predicts the shape of the stamped component after forming,

trimming and springback for inner leads. The next blanking process is executed repeatedly

until the final blanking of lead. From the results of FE analysis using suggested method in this

research, it is possible to predict the lead shift of leadframe to manufacture high precision

leadframe in progressive blanking process and these results might be used as a guideline to

optimize layout design system in multihole blanking process.

Sung-Bo Sim, Sung-Taeg Lee and Chan-Ho Jang [2] presented ‘A study on the

development of center carrier type progressive die for U-bending part process’. The Center

carrier-type progressive die for U-bending sheet metal production part is a very specific

division. This study reveals the sheet metal forming process with multi-forming die by Cut off

type feeding system. Through the FEM simulation by DEFORM, it was accepted to U-

bending process as the first performance to design of strip process layout. The next process of

die development was studied according to sequence of die development, i.e. die structure,

machining condition for die making, die materials, heat treatment of partially die components,

know-how and so on. The feature of this study is the die development of scrapless progressive

die of multi-stage through the Modeling on the I-DEAS program, components drawing on the

Auto-Lisp, CAD/CAM application, ordinary machine tool operating and revision by tryout.

J.C. Choi and Chul Kim [3] were presented journal as ‘A compact and practical

CAD/CAM system for the blanking or piercing of irregular shaped-sheet metal products for

progressive working’. This paper describes research work into developing the computer-aided

design and manufacturing of stator and rotor parts with blanking or piercing operations. An

approach to a CAD/CAM system is based on knowledge-based rules. Knowledge for the

CAD/CAM system is formulated from plasticity theories, experimental results and empirical

knowledge of field experts. The program for the system has been written in AutoLISP on the

AutoCAD for strip- and die-layout and in customer tool kit on the Smart CAM software for

modeling and post processing with a personal computer. It is composed of nine modules,

which are input and shape treatment, flat pattern-layout, production feasibility check, blank-

layout, strip-layout, die-layout, data-conversion, modeling, and post-processing modules.

Based on knowledge based rules, the system is designed by considering several factors, such

as the material and thickness of product, the complexities of blank geometry and punch

profile, the diameter and material of a wire, the working conditions, and the availability of a

press. It is capable of generating automatically NC data to match tooling requirements by

checking dimensions according to the drawings of the die-layout module. Results obtained

using the modules enable the design and manufacturer of stator and rotor parts to be more

efficient in this field.

H. S. Ismail, S. T. Chen and k. K. B. Hon [4] were presented paper on the topic of

‘Feature-Based Design of Progressive Press Tools’. This paper outlines two approaches for

the development of a feature-based system which is used to support the detailed design of

progressive press tools. The first approach is based on applying a coding technique to

characterize the work piece geometric features. This feature description is subsequently used

to propose the type and layout of the press tool punches required to produce the part. The

second approach uses design constraints as the bases for selecting the punches and dies. The

approaches have been implemented on an IBM PC in C and integrated with a prototype low-

cost CAD system for press tool design.

Chul Kim, Y.S. Park, J.H. Kim and J.C. Choi [5] were presented paper as ‘A study on

the development of computer-aided process planning system for electric product with bending

and piercing operations’. This paper describes a research work of developing computer-aided

design of product with bending and piercing operation for progressive working. Approach to

the system is based on the knowledge-based rules. Knowledge for the system is formulated

from plasticity theories, experimental results, and the empirical knowledge of field experts.

The system has been written in AutoLISP on the AutoCAD with a personal computer. It is

composed of four main modules, which are input and shape treatment, flat pattern layout, strip

layout, and die layout modules. The system is designed by considering several factors, such as

bending sequence by fuzzy set theory, complexities of blank geometry, punch profiles, and the

availability of press equipment and standard parts. The strip layout and die layout drawings

automatically generated by formularization and quantification of experimental technology will

make minimization of trial and error and reduction of period in developing new products.

Results obtained using the modules enable the manufacturer for progressive working of

electric products to be more efficient in this field.

Keun Park and Sang-Ryun Choi [8] were presented ‘Finite element

analysis for the lamination process of a precision motor core using

progressive stacking dies’. In order to increase the productivity of electrical parts,

manufacturing processes using progressive dies have been widely used in the industry. Motor

cores have been fabricated using progressive stacking dies with lamination in order to obtain

better electro-magnetic properties. For proper design of the process, a prediction of the

process is required to obtain relevant design parameters. In this work, rigid–plastic finite

element analysis is carried out in order to simulate the lamination process of the motor core.

The effects of the embossing depth and the number of stacked sheets are investigated and

compared with experimental results. The forming process can then be predicted successfully

from the results of analyses, enabling the development of an appropriate design for the die and

the process.

CHAPTER 3

TERMINOLOGY OF PROGRESSIVE TOOLS

3.1 PROGESSIVE TOOLS WORKING TERMINOLOGY

Before beginning the study of die making it is necessary to attain a clear understanding

of the following terms.

Stock Material

General term for any of the various materials from which the piece parts is made.

Day Light

Day light is the distance between top surface of the bottom shoe to the bottom surface

of the top bolster when the tool is in open condition.

Shut Height

The distance from the bottom surface of the bottom shoe (bottom plate) to the top

surface of the top bolster (top plate) when the tool is in closed condition as known as shut

height.

3.2 PARAMETERS IN CUTTING TOOLS

Blank

In blanking operation, the entire periphery is cut and the cut out piece is called blank.

Slug

In piercing operation the entire periphery is cut and the cut out piece is called slug or

waste.

Piece Part

It is a product of die. It may be complete product itself or it may be a component of

product may be designed without die shoe by incorporating fixtures for attaching them to the

ram and bolster plate of the press.

CHAPTER 4

ELEMENTS OF PROGRESSIVE TOOLS

4.1 DIE SET

The die set is one of the basic elements of the stamping industry. It can be defined as a

sub press unit consisting of a bottom plate and top plate together with guide pillars and bushes

by means of which the top and bottom plates are aligned.

The purpose of die set is to utilize the entire die assembly. Some of the advantages

realized by assembling die components to a properly selected die set are:

Accuracy die set up.

Improved piece part quality.

Increased die life

Minimum set up time.

Facilitation of maintenance.

Alignment of punch and die members.

Facilitation of storage.

4.2 TOP BOLSTER (TOP PLATE)

The upper working member of the tool is called the top plate. The punch assembly

including the punch holder and thrust plate is mounted on the top plate. The tool shank, which

locates the whole tool centrally with the press ram, is also screwed into the top plate. And the

material of the top plate is ST-42.

4.3 PUNCH BACK PLATE OR THRUST PLATE

While performing the cutting operation, the punch exerts and an upward thrust. So a

hardened plate to prevent it from digging into the soft-top plate should back up punch. It is

made out of case hardened tool steels or sometimes OHNS. It is hardened and tempered to 45-

48 HRC.

4.4 PUNCH PLATE

The punch is usually fixed to a plate with a light press fit. Punch holder holds the all

types of cutting and non-cutting punches to ensure alignment between punch and die it is

made out of ST-42.

4.5 PUNCHES

A punch is the male member of a press tool to get a component from the strip. It is

made out of good quality alloy steel called H.C.H.Cr. (T215Cr12W90) material and hardened

to 58-60 HRC.

4.6 STRIPPER PLATE

When cutting action is over, the punch withdraws from the die but the stock strip also

will move along with punch. So for next operation strip cannot be moved forward. To

facilitate this function one plate is fixed above the die plate. This remove the strip from the

punch is called stripper. It guides punches and pilots in this plate to ensure alignment with

punch and die.

It is made of O.H.N.S. material (T110W2Cr1). It is hardened and tempered to 50-52

HRC.

4.7 DIE PLATE

A die block is defined as the block or plate from which the die profile is cut. It is

usually lower member of the tool. It is usually made from T215Cr12W90 material and is

hardened to 60-62HRC. It provides cutting edge. The die opening has different designs and

the design is selected after looking in the requirements and facilities available. The most

common die section has straight line and then angular clearance is given in order to allow easy

fall of components and slugs. Button inserts can be used conveniently for circular holes.

Large dies are made from many segments, which are secured in a sturdy die holder (bottom

bolster) by Allen-screws and dowels.

Many factors influence design of die blocks.

Weather the die block is conventional or special purpose machining.

Shape and complexity of the profile.

Size and thickness of the component.

Production requirement.

Quality of the component.

Hardness of the component.

Machining facility available.

4.8 BOTTOM BOLSTER (BOTTOM PLATE)

Bottom plate gives cushioning effect to the die as well as provides enough space for

the tool to be clamped to the press bed. There may be opening in the base plate, which allows

the blank, or slug to fall and clear off from the tool. The die assembly including stripper, all

bottom elements are mounted on the bottom plate.

4.9 GUIDE PILLAR AND GUIDE BUSH

Guide Pillar and Guide Bush are very important function in press-tool. Pillar and

bushes guide the moving and fixed half of the tool in the press and also it is used to ensure

accurate alignment between the punches and die

These are made out of case hardened tool steel (17Mn1Cr95) or some times O.H.N.S.

(T110W2Cr1). Pillar and bushes are hardened and tempered to 56-58 HRC.

4.10 STOPPERS

After each and every stroke of press the strip has to be fed from one pitch length. This

can be accomplished by means of a stopper. The function of the stoppers is to arrest the

movement of the strip.

It is made out of hardened tool steels. It is hardened and tempered to 48-50 HRC.

4.11 PRESSURE PAD

Pressure pad are commonly actuated by spring or rubber cylinders. Where more pressure

is necessary, the die is usually installed in a press which is equipped with an air cushion.

Hydraulic cylinders can also be used to actuate pads when strong pressure is required. In

Bending Die, the pressure pad performs the following functions. Which are listed in order of

operational sequence,

They hold the work piece during bending.

They serve as bottoming blocks for setting of the bed (or beds).

They act as strippers or shedders to aid in removing the piece part from the Die.

4.12 EJECTORS

In the conventional position die is the lower member of the tool (being clamped to die

shoe). If the ejection of the blank is achieved by forcing it upwards, the action is known an

ejecting. The element of the tool, which ejects the blank, is called an ejector.

4.13 SHEDDERS

In inverted tool, die becomes the upper member of the tool being clamped to the press

ram. The ejection of the blank is achieved by forcing them downwards. This action is

generally known as shedding and element of the tool which sheds the blank is known as

shedder.

4.14 KNOCK OUT

A mechanism for ejecting blanks on other work from a die commonly located on a

slide but may be located on the bolster.

CHAPTER 5

DESIGN ASPECTS AND ANALYSIS

Tool design is a specialised phase of tool engineering. While designing the tool, the

drawing of the elements to be manufactured with sufficient required details, name and

specification of the machine to produce the elements and the number of elements required will

be provided.

In all cases the tool must be made as economically as possible for the required service,

the tool should be easy and safe to operate; it should be practical and attractive but should not

have elaborate trimmings or needless complexity. After component analysis it was decided to

go for progressive Tools.

The following design point should be considered carefully,

1. Controlling location of the scrap strip.

2. Guidance should be extended at least two-scrap width in front of first Station.

3. The type of stripper used.

4. Channel clearance should be adequate to allow the strip to move freely.

5. Location of strip by means of locating pins must be provided.

6. Die block should be longer and wide enough so that the location of the holes will be at

least one and half time the thickness of the block away from the edge.

7. Dowel should be a safe in non-cylindrical location so that section or parts may be

mounted in one position only.

8. Counter bore in the die block, the tapped hole in the die shoe and reamed holes in the

die shoe must be made from 6 to 9 mm deeper than needed to allow for grinding of die

block.

9. Choose the die shoe, so that when the die block is mounted it can be ground without

removing it from the die shoe.

10. Small profile punch should be guided in the stripper plate.

Fig 5.1.1 Flow Chart of Design Aspect and Analysis

The design aspect and analysis that has been adopted in this dissertation work to do a

successful tool design includes the following steps.

Component study and 3D-solid modeling of the Component

Design of the Tool

Selection of proper tooling materials

3D solid modeling of the Tool

Analysis of the Tool

5.1 DESIGN CALCULATION

5.1.1 COMPONENT DATA

Material: mild steel (St-42)

Supply conditions: strips

Temper grade: hard

Shear stress: 35 kg/mm2

Geometry tolerance: IS2120

Fig. 5.1.2 Component Diagram

Table 5.1 Chemical and Physical Properties of C42-Steel

COMPONENT C FE MN P S

Weight (%) 0.4 - 0.48 97.5 - 98.01 1.35 - 1.65 Max 0.04 0.24 - 0.33

Physical Properties Metric English Comments

Density 7.87 g/cc 0.284 lb/in³ Typical for steel.

Mechanical Properties

Hardness, Brinell 235 235

Hardness, Knoop 259 259Converted from Brinell

hardness.

Hardness, Rockwell B 97 97Converted from Brinell

hardness.

Hardness, Rockwell C 21 21Converted from Brinell

hardness.

Hardness, Vickers 247 247Converted from Brinell

hardness.

Tensile Strength, Ultimate 786 MPa 114000 psi

Tensile Strength, Yield 670 MPa 97200 psi

Elongation at Break 14 % 14 %

Reduction of Area 36 % 36 %

Modulus of Elasticity 210 GPa 29000 ksi Typical for steel

Bulk Modulus 140 GPa 20300 ksi Typical for steel.

Poisson's Ratio 0.29 0.29 Typical For Steel

Izod Impact 43 J 31.7 ft-lb normalized at 900°C, 65 J

http://www.matweb.com/search/GetUnits.asp?convertfrom=59&value=43







http://www.matweb.com/search/GetUnits.asp?convertfrom=43&value=7.87

annealed at 815°C, 53 J as rolled

Shear Modulus 80 GPa 11600 ksi Typical for steel.

Electrical Properties

Electrical Resistivity1.7e-005 ohm-

cm1.7e-005 ohm-cm

condition of specimen unknown; 20°C (68°F)

Thermal Properties

CTE, linear 20°C 11.5 µm/m-°C 6.39 µin/in-°F Typical steel

CTE, linear 250°C 12.2 µm/m-°C 6.78 µin/in-°FTypical for steel ; 0-300°C (68-

570°F)

CTE, linear 500°C 13.9 µm/m-°C 7.72 µin/in-°FTypical for steel ; 0-500°C (68-

930°F)

CTE, linear 1000°C 14.7 µm/m-°C 8.17 µin/in-°F Typical steel

Specific Heat Capacity 0.472 J/g-°C 0.113 BTU/lb-°F Typical steel

Thermal Conductivity 51.9 W/m-K 360 BTU-in/hr-ft²-°F Typical steel

Subcategory: AISI 1000 Series Steel; Carbon Steel; Medium Carbon Steel; Metal

Close Analogs: AISI 1141

Material Notes

Applications include cold drawn or finished bar, electrical insert, cold punched nuts, split rivets,

machine screws and wood screws.

5.1.2 STRIP LAYOUT

The disposition of part on the strip feed unfolding was displayed with a constant area

repeatedly.

Due to upper cause, it must be enough that the decision of strip feeding distance

(advance, pitch) and disposition of each stage on the strip lay out are performed exactly. Our

intention considered that the best utilization ratio of sheet metal can be obtained as taking the

accurate strip process layout design through the theoretical calculation and field experiences.

This is the optimum method of initial die design. At this time we referred the web size

on the strip from database and its related instructions.







http://www.matweb.com/search/GetUnits.asp?convertfrom=116&value=1.7e-005

http://www.matweb.com/search/GetUnits.asp?convertfrom=116&value=1.7e-005


Fig. 5.1.3 Flow Chart of Strip Process Layout Design

Fig.5.1.3 shows the flow chart strip process layout design system. For the design of

strip process layout, the first step is how to decide the feeding method according to the

quantity of production part, accuracy of production part, material properties, and material

thickness, the second step is followed to this flow chart of Fig. 5.1.3 and Fig. 5.1.4 showing

the production part and its length (70 mm) used to the thick sheet metal (material: mild steel

and thickness: 2.0 mm) production part.

Two types of strip layouts are used for design the optimized strip layout.

1. wide row strip layout

2. narrow row strip layout

Wide row strip layout

Scrap allowance (A)

SL.NO Type of component Single row Multi row1 Curved component 0.75t 1.25t2 Straight component 1.0t 1.5t

A = 1t (for straight component and single row strip layout)

= 1x2.00 = 2.00mm

Strip width (W)

W = 2 x A + Length of component

= 2 x 2 + 70 = 74.00mm

Pitch (P)

P = width of component + A

= 30 + 2 = 32.00mm

Component area (a)

A = (30 x 70) - {(5x5) – (π x 2.52)} = 2094.6425mm2

Percentage of material area utilization

Area of blanks from strip weight of blanks/strip = --------------------------------------- = --------------------------------------

Area of the strip before blanking weight of strip before blanking

Area of blank x no. of rows = ---------------------------------

Area of strip per pitch = (2094.6425 x 1 x 100) / (74 x 32) = 88.45%

Fig. 5.1.4 Wide Row Strip LayoutNarrow row strip layout

Scrap allowance (A)

A = 1t (for straight component and single row strip layout)

= 1x2.00 = 2.00mm

Strip width (W)

W = 2 x A + Length of component

= 2 x 2 + 30 = 34.00mm

Pitch (P)

P = width of component + A

= 70 + 2 = 72.00mm

Component area (a)

A = (30 x 70) - {(5x5) – (π x 2.52)} = 2094.6425mm2

Percentage of material area utilization

= (2094.6425 x 1 x 100) / (34 x 72) = 85.56%

Fig. 5.1.5 Narrow Row Strip Layout The strip process layout was considered that the proper sizes are strip width, web-size,

advance, notching allowance, etc.

The first stage operates piercing, the second stage works piloting and oblong piercing,

the third stage works notching, and fourth stage works blanking as a complete stage.

We must take care of pilot damage or its fracture through the causes of dislocation on

the every stage. After that, the strip process layout was obtained as a result in Fig. 5.1.4 and

Fig 5.1.5.

Here the percentage of material utilization of wide row strip layout (88.45%) is higher

than narrow row layout (85.56%). Therefore the wide row strip layout is chosen for

implementation of design and manufacturing of progressive tool.

5.1.3 SHEAR FORCE (Fs)

Shear force, Fs = shear area x shear stress

Fs = periphery cut x sheet thickness x shear stress

Fs = L t fs

Shear Force for Piercing Ø 8mm X 2Nos. hole Operation (Fsp)

Fsp = π x 8 x 2 x 35 x 2

Fsp = 3518.58 kgf

Shear Force for Oblong hole piercing Operation (Fso)

Fso = 48.85 x 2 x 35

Fso = 3419.47 kgf

Shear Force for Notching Operation (Fsn)

Fsn = 39.57 x 2 x 35 x 2

Fsn = 5539.80 kgf

Shear Force for Blanking Operation (Fsb)

Fsb = 195.71 x 2 x 35

Fsb = 13699.56 kgf

Total Shear Force (Fsh)

Fsh = 3518.58 + 3419.47 + 5539.80 + 13699.56

Fsh = 26177.41 kgf

Stripping force (Fsf)

Here the thickness of sheet metal is 2mm, so no need to use stripping loaded stripper.

If the sheet thickness is less than or equal to 1mm, we can use spring loaded stripper in the

press die. And always stripping force will be 15 to 20% of the total shear force required.

Fsf = 15 to 20% of total shear force required

= 0.15 x 26177.41

= 3926.61 kgf

5.1.4 PRESS CAPACITY (Pc)

Press tool is to be loaded 70 to 80 percentage of the rated press capacity for consistent

performance.

Pc = (total shear force + stripping force) x FOC / 70 to 80% of press capacity

Pc = (30104.02 x 1.2 x 100) / 70

Pc = 37396.3 kgf

Pc = 37.39 Tones ≈ 38 Tones

The presses are manufactured to press tonnage capacity as per preferred numbers like 5, 10,

16, 20, 25, 40, 50, 63, etc.

Therefore choose the nearest available press tonnage capacity as,

Pc = 40 Tones

5.1.5 CLEARANCE(C)

C = 0.005 x t x √Fsh if t ≤ 3mm

C = (0.01t – 0.015) x √Fsh if t > 3mm

C = 0.005 x 2 x √35

C = 0.06 mm per side

Otherwise by using percentage table for various materials

Material Mild steel Aluminium BrassClearance % of sheet thickness 2.5-5% 1.5-3% 1.5-3%

C = 3% of sheet thickness

C = (3 x 2) / 100

C = 0.06 mm per side

5.1.6 CENTRE OF PRESSURE

Three method are used for calculating centre of pressure as,

Centre of Gravity Method

Moments Method

Graphical Method

Centre of Gravity Method

X’ = ∑Li Xi/∑Li i = 1, 2, 3…

Take reference line away the blanking centre, say 50.00mm

L1 = 186.714 X1 = 50.00

L2 = 79.142 X2 = 82.00

L3 = 48.856 X3 = 114.00

L4 = 50.284 X4 = 146.00

X’ =78.73mm

Centre of pressure from blanking centre is = 78.73 – 50.00 =28.73mm

Y’ = ∑Lj Yj /∑Lj j = 1, 2, 3…

Take reference line away the edge of strip, say 50.00mm

L1 = 39.571 Y1 = 58.89

L2 = 25.142 Y2 = 60.00

L3 = 244.564 Y3 = 87.00

L4 = 39.571 Y4 = 114.00

L5 = 25.142 Y5 = 115.11

Y’ = 86.96mm

Centre of pressure from strip edge is = 86.96 – 50.00 =36.96mm

Graphical Method

Fig. 5.1.6 Graphical COP Method of Wide Row Strip Layout

5.1.7 DIE BLOCK DESIGN

Die block dimensions are governed by the strength necessary to resist the cutting

forces and will depend on the type and thickness of the material being cut.

The force required to drive a punch through the stock material is the cutting force for

that particular punch. If a die has more than one punch acting simultaneously, the cutting force

for that die is the sum of the stock material.

In any cutting die, the importance of cutting force is to select a punch press of proper

tonnage rating for the job.

Shear strength of stock material must be known in order to calculate cutting force

because the shear resistance of stock material is overcome by the punching force.

Relation of cutting force to shearing action is described as follows,

Cutting force, Fsh = shear strength of stock material x cut edge area

Resistance begins when the punch contacts the stock material. The load builds up

rapidly during the plastic deformation stage and continuous to increase while penetration is

taking place. The accumulated load is released when fracture occurs. If a proper cutting

clearance exists between punch and die, fracture will occur when the cutting force equals the

shear strength of stock material of die. Thickness of die block is found by using empirical

formula as,

Thickness of die block, TD = 3√Fsh

If the Fsh is in tones the thickness TD is in centimeters and if Fsh is in kilograms the

thickness TD is in mm.

For this thickness, regrinding allowance should be added which increases the die life.

Generally 3 to 5 mm is added.

Die block thickness, Td = TD + 3 to 5 mm however at any case the thickness should

not be less than 20 mm.

Thickness of die block (TD)

TD = 3√Fsh here, Fsh - Total Shear Force

= 3√26177.41

TD = 29.69 mm

Otherwise also use as,

TD = 3√Press Tonnage

= 3√40 x 1000

TD = 35.00mm

Therefore Thickness of die block, (TD) =35.00 mm

Length of Die Block (LD)

LD = (1.5 TD + greater length b/w from cop point) x 2

= (1.5 x 35 + 71.33) x 2

LD =252.00mm

Width of Die Block (WD)

WD = (2 x 1.5 TD) + length of component

= (2 x 1.5 x 35 + 70.00)

WD =176.00mm

Die block dimension is (252 x 176 x 35) mm

Land and draft

From CITD standards land will be 3-6 mm and draft will be 1/4º to 1/2º

Take 5mm land and 1/2º draft

If draft is not given internal stresses may develop in the hole from accommodate of

scrap or component and die block will get crack.

Fastness (Allen screw)

The transverse force is acting on die block, which is used to hold the die part together

by means of screws.

Therefore the transverse force is acting on die block as usually 20 – 30% of total shear

force of the tool.

The transverse force = 20% of total shear force

= 0.20 x 26177.41 kgf

= 5235.482 kgf

Let the No. of screws required is minimum Four.

Transverse force = shear area x shear strength x No. of screws x safety factor

5235.482 = (π x D2 x fs x N x S)/4

D = Ø9.999 mm

D = M10

The nearest highest value M10 is chosen for factor of safety. And hole diameter is

Ø8.5 mm and pitch is 1.25 mm.

The minimum wall thickness from the edge of the die block to centre line of screw is

9D/8 = 15.00 mm.

The designed detail diagram of die plate has shown in the fig 5.3.4

5.1.8 DIESET DESIGN

Most bed has large openings to permit the installation of air cushions of scrap, blanks

or part. The bottom plate must be rigid and not deflect excessive into the bed opening.

Otherwise the clearance or die alignment is impaired. The mathematical analysis is greatly

simplified assuming that the bottom plate is considered to be on parallels. The shoe deflection

is calculated using the strength of material formula,

Deflection, δ = FL3/354EI (For bottom plate consider as parallels supported beam)

Deflection, δ = FL3/354EI (For top plate consider as simply supported beam)

Where, F = 80% of cutting force = 0.8 x 26177.41 kgf = 20941.93 kgf = 209419.3 N

L = distance between parallel

E = modulus of elasticity

I = bh3/12 (moment of inertia)

Where, b = length of bottom plate

h = thickness of bottom plate

Stress, p = F/A

Where, A = cross sectional area

As per GTTC kinetic standard the length of guide bush in top plate (D) should be

32.00mm and total length of guide bush will be 64.00mm. The inner diameter and outer

diameter will be Ø22H7 and Ø32h6 respectively.

Thickness of top plate, TTP = 1.25 TD = 42.00mm

Length of top plate, LTP = length of die block + (2 x (9D/8))

= 252 + (2 x (9 x 32/8)

LTP = 326.00mm

Width of top plate, WTP = width of die block + [2 x ((9D/8) + (D/2) + 2)]

= 176 + [2 x (9 x 32/8) + (32/2) + 2)]

WTP = 286.00mm

Top plate dimension is (286 x 326 x 42) mm

The designed detail diagram of top plate has shown in the fig 5.3.1

Thickness of bottom plate, TBP = 1. 5 TD = 52.00mm

Length of bottom plate, LTP = length of die block + (2 x (9D/8))

= 252 + (2 x (9 x 32/8)

LBP = 326.00mm

Width of bottom plate, WBP = width of die block + [2 x ((9D/8) + (D/2) + 2)]

= 176 + [2 x (9 x 32/8) + (32/2) + 2)]

WBP = 286.00mm

Bottom plate dimension is (286 x 326 x 52) mm

The designed detail diagram of bottom plate has shown in the fig 5.3.2

5.1.9 STRIPPER PLATE DESIGN

After a blank has been cut by the punch on its downward stroke, the scrape strip has a

tendency to contract. On the return stroke of punch, the scrap strip tendency to adhere to the

punch and be lifted by it. This action interferes with the feeding of the stroke through the die,

some device must be used strip the scrap material from the die block, such a device is called

stripper. Strippers are of two types.

Fixed stripper or box type stripper

Floating stripper or spring loaded stripper

Fixed stripper

Fixed stripper is attached at a fixed height over the die block. The height should be

sufficient to permit the sheet metal to be fed freely between the upper die surface and under

surface of the stripper plate. The stripper plate is usually of same width and length as the die

block.

For the stripper action on the upward movement of the punch, the scrap strip will

strike the underside of the stripper plate and get stripped off from the punch. The underside of

the stripper plate which comes in contact with the strip should be machined and preferably

ground.

The mathematical analysis is simplified by assuming fixed stripper to be considered as

a fixed beam support The fixed stripper plate deflection and stress is calculated using the

strength of material formula,

Deflection, δ = FL3/192EI

Where, F = 10% to 20% of cutting force = 0.2 x 26177.41 kgf = 5235.48 kgf = 52354.8 N

L = distance between two successive screws = 222 mm

E = modulus of elasticity = 2.1 x 105 N/mm2

I = bh3/12 (moment of inertia) = 1.17x 105 mm4

Where, b = length of stripper plate = 176 mm

h = thickness of stripper plate = 20 mm

Stress, p = F/A


Stripping force depends on many factors, including stock thickness, cutting perimeter,

physical properties of stock, punch clearance, stock lubrication and scrap allowance.

Spring loaded stripper

Spring loaded type stripper is used on large blanking operations and also on very thin

and highly ductile materials where it is desirable to utilize the pad pressure to hold the

surrounding stock during the blanking operation. In this design the stripper is mounted over

compression springs and suspend by bolts from the punch holder, with the lower surface of

the stripper below the cutting end of the punch. As the punch travels downward for the

blanking operation the stripper plate contacts the stock strip first and holds it until the punch

clears the strip on its return stroke. As the ram rises the spring pressure strips the stock

holding in the punch. In this case, the stripping force may be as high as 20% of cutting force

and the spring can be designed accordingly. The stripper is to be guided either in main pillars

or in auxiliary pillars.

The mathematical analysis is simplified by assuming simply supported beam. The

spring loaded type stripper plate deflection and stress is calculated using the strength of

material formula,


Where, F = 10% to 20% of cutting force

L = distance between two successive screws


I = bh3/12 (moment of inertia)

Where, b = length of stripper plate

h = thickness of stripper plate

Spring loaded stripper is used when

Stock thickness is less than 1 mm

The number of stations are more

If verity of operations are present

If the length of channel is too much

Dimension of stripper plate is same as the die block dimension except the thickness. The

thickness of stripper plate as per GTTC standards has 16 to 20 mm therefore take 16 mm.

The dimension of stripper plate is (252 x 176 x 16) mm

The detail designed drawing of stripper plate is shown in the fig 5.3.7

5.1.10 GUIDE PLATE DESIGN

The height of guide plate is governed chiefly by two factors, the kind of stop and the

stock thickness. If there is no stop the height may be much lower when compared with stops

introduced. Because when stops are used a suitable space must be provided for the easy

passage of the strip.

Generally, the height is 1.5t to 2t is taken where ‘t’ is stock thickness. If the height is

greater than 2t there is a chance of feeding two strips, to avoids this height is kept less than 2t.

For less than 1mm thickness, height of 2.5 mm is provided.

Rather than the height of guide plates the important factor in case of guide plate is the

guide width. The guide width has to be tolerance such that the strip moves freely between the

guides at the same time there should not be any play in the strip.

Width of the Guide Plate, Wg = Width of Strip + Tolerance on Strip + Feeding Clearance +

Manufacturing tolerance

Tolerance on strip ± 0.2 for coil

+ 0.0 for strip

- 0.4

Feeding clearance = 0.1 to 0.2 mm

Manufacturing tolerance = ± 0.05 to + 0.1

- 0.0

The length of the guide plate is made more than the length of die block and at the entry

it is tapered at 10 to 15° for easy entry of strip as shown in figure. The guide plates are

extended by 30 to 50mm beyond the die block. In order to support strip, strip back plate is

fastened under the surface of the extended portion. The thickness of the guide plate is from

0.15t to 0.2t (t is die block thickness).

In case of floating stripper the guide is provided with a hood so that strip does not get

lifted or come outside the guide plates.

Width of guide plate, Wg = 74 - 0.1 + 0.2 + 0.05 = 74.15 mm

Thickness of guide plate Tg = 0.15 x 35 = 6 mm

The detail designed drawing of guide plate has shown in the fig 5.3.8

5.1.11 GUIDE PILLAR DESIGN

Since alignment is a matter of maintaining clearance, the allowable clearance variation

should be used in designing the die details. Most die operations cause on increase in clearance

due to side thrusts.

Guides pin are originated to provide alignment when the die is exerting forces to shape

metal. That is necessary to maintain proper clearance between the components shaping the

metal. More specifically, clearance must be help to close limits between the punch and die

steels. The purpose of clearance varies in each operation.

In cutting, clearance is needed to obtain a clean fractured edge. Excessive clearance

allows pull-in of metal and large burr formation. Insufficient clearance causes missing of the

fractures and resulting jagged edge with excessive burnishing. The bust cutting clearance

varies from 5 to 20% of the sheet thickness, depending on the hardness of the metal.

Forming and drawing clearance is needed to allow room for the sheet metal thickness

between the steels.

Insufficient clearance causes burnishing of metal, and without proper lubrication and

surface finish galling or scoring bends becomes a problem. Excessive clearance means that

square bends and straight walls are not possible since a taper is created.

Similar side thrusts occur during right angle bending and cup drawing operations.

Large side thrusts are present when cams are used. For 45º cam, neglecting friction, side thrust

equals the vertical force. Another cause to side thrust may be press ram which is not parallel

to the bed. Dies that are somewhat self aligning, such as many form or draw dies, will attempt

to overcome this situation.

Causes of side thrusts in dies are itemized as follows,

Side thrusts due to the clearance used in cutting, forming and drawing die.

Side thrusts necessary to align the ram.

Side thrusts due to poor alignment of components during die construction.

Side thrusts due to angular contacts between surfaces, such as with cams, dies

and punch steels.

Side thrusts resulting from the use of shear or angular cutting faces to reduce

force requirements.

Side thrusts occurring in cut off, trim, bending and flange dies where forces act

on only one edge of the steels.

Side thrusts created by non symmetrical forms or draws where punch and die

are loaded off center at initial contact.

After knowing the vertical force, side thrust and allowing a pillar deflection of 0.05 to

0.01 mm, the diameter of pillar is calculated. The mathematical analysis is simplified

assuming that the guide pillar as a cantilever beam.

Select the die view in which the pin deflection will cause a clearance change.

The diameter can be calculated using the deflection formula,

Y = FL3 /3EI

If two pillars are used, one on each side then above formula is used.

If four pillars were used, two pins are considered non-existent then,

Y = FL3 / 6EI

Permissible deflection Y is clearance between pillar and bush. Because of presence of

other pillars it is not possible. So Y is taken as 0.05 to 0.01 mm sometimes 0.005 mm.

Before guide pillar design knowledge of forces occurring during stamping operations

are considered, first the vertical die force must be known. Then the vertical forces must be

analyzed to see if any side thrusts are created, it is this horizontal force that causes many

problems of alignment before any practical calculations can be made, these horizontal forces

must be known.

A theoretical study of vector force in a cutting die from the gage curve shows one

approach to the problem. Note that triangle abc represents the physical relation of the punch

and die near maximum force conditions. Side ac represents the clearance, side bc represents

the sheet metal thickness less the penetration at fracture completion. This same triangle also

represents the force distribution. Side bc would be the vertical cutting force and side ac the

horizontal vector. Having calculated the vertical force with known shear strengths a ratio can

be used to find side thrust,

Clearance horizontal force------------------------------------- = ---------------------- (Sheet thickness – penetration) vertical force

Fit recommended between guide pillar and bottom bolster (bottom plate) is H7/p6,

guide pillar and guide bush is H7/h6 or H7/h5 and guide bush and top bolster (top plate) is

H7/p6.

When the stroke is at bottom dead center (BDC), the pillar and bush should have a

minimum engagement equal to 1d to 1.5d before actual operation starts and also the pillar

should not project above the top surface of top plate. It is better to have length of pillar less

than 100.

The diameter of guide pillar is 28 mm and length of pillar is 184 mm. The designed

detail diagram of guide pillar has shown in the fig 5.3.3

The dimension of guide pillar is (Ø22 x 184) mm

Table 5.2 Dieset Details

Sl.No. Description Material Size (L x W x T)mm Remarks(HRC)01 Top plate M.S (St-42) 286 x 326 x 42 -02 Bottom plate M.S (St-42) 286 x 326 x 52 -03 Guide bush 17Mn1Cr95 Ø56 x 64 58-6004 Guide pillar 17Mn1Cr95 Ø22 x 184 58-60

Table 5.3 Plates details

Sl.No. Description Material Size (L x W x T)mm Remarks01 Die plate T110W2Cr1 (OHNS) 252 x 176 x 35 58-60HRC02 Punch plate M.S (St-42) 252 x 176 x 16 -03 Punch back plate T110W2Cr1 (OHNS) 252 x 176 x 8 54-56HRC04 Stripper plate T110W2Cr1 (OHNS) 252 x 176 x 20 54-56HRC

5.1.12 PUNCHES DESIGN

Punch is of the same shape as that of the operation to be performed.

Punch hardness is high compared to that of work material (as much as 20 HRC).

It should have high compressive and tensile strength.

It should not deflect.

It should be capable of resharpening.

During operation, due to load acting from both sides of punch i.e. compressive stresses

or waviness of strip the punch may enter into the die in an angle. This has a tendency of

incorrect clearance all around which results in unequal wear, it may also damage or break the

punch or chip off the die.

Since the force is in acting on both sides of the punch, it is treated as a column and

designed for buckling load.

The buckling load which is a function of slenderness of the punch, if it is higher the

punch may break. As the buckling load coming on it will not buckle the punch as it is

hardened but it will result in breakage.

To encounter deflection of the punch a proper clearance is to be provided in the plate

as well as a proper guiding clearance is to be provided in the stripper.

To encounter the punch from buckling the punches have to be safe from buckling load.

So using Euler’s formula we have to check for buckling load. It should be less than the cutting

force. If the buckling load is higher it cad be made lower by providing a step with larger

diameter at buckling portion of the punch end. This increases the punch strength.

Euler’s formula is given by,

Fb = π2 n E I / L2

Where,n = 1, constant for both ends guided or hinged

E = modulus of elasticity

I = π d4 / 64

L = unguided length of punch

Fb= buckling force.

For example consider a circular punch,

Fb = π2 n E I / L2 = π d t Ss

Where,d = diameter of hole

t = stock thickness

Ss= shear stress

Substituting for n and I in above equation we get length of punch

L = (π d /8) √ (E d / Ss t)

This equation indicates the maximum length of punch which resists deflection with

proper clearance in punch plate and in guiding stripper. It is also always necessary to check

the compressive stress of the punch. The compressive stress of punch should not exceed 70 to

80 kgf / mm2

As similar to buckling load if the compressive stress is high, it is reduced by using a

stepped punch.

Here we can consider the condition as the compressive force of punch is equal to the

shear force (cutting force) of sheet metal cutting.

Cutting force Compressive stress on punch, Sc = -----------------------------------

Cross sectional area of punch

Sc = 4 π d t Ss / π d2 = 4 t Ss /d

The above equation indicated that, to pierce a hole equal to stock thickness the

compressive stress should be four times the shear stress.

If the compressive stress exceed between the punch plate and punch holder to take the

cutting pressure on punch head from being forced into the softer holder this becoming loose.

As a general rule, back up plate is employed whenever the punch diameter is less than

four times the stock thickness. Back up plate is generally made up of plain carbon steel,

hardened parallel.

Depending on the punch construction, the unit compressive stresses for different

punches are shown below the respective punches.

Die bushing subjected to high stresses are also to be supported by buckling plates.

The thickness of buckling plate depends on stock thickness and generally 5 to 10 mm

is recommended.

In punch the collar area is subjected to force therefore the collar thickness is increased

to a hardness of 45 – 48 HRC.

Holes having diameters less than stock thickness can be successfully punched. The

punching of such holes can be facilitated by,

Punch steels of high compressive strength

Greater than average clearances

Optimum punch alignment, finish and rigidity

Shear on punches or dies or both

Prevention of stock slippage

Optimum stripper design

Design of piercing punch

For piercing operation punch size is on per component diameter and die size is add 2C

with hole diameter (clearance is given in die size). For blanking operation die size is on per

component size and die size is reduce 2C with component size (clearance is given in punch

size).

Diameter of piercing punch d = Ø8 mm

Diameter of piercing on die block d1 = d + 2C

d1 = 8 + 2 x 0.06 = Ø8.12 mm

The maximum length of punch Lmax = 7.5 x √ (d3/t)

Where, d - Diameter of piercing punch

t – Thickness of the strip

Lmax = 7.5 x √ (83/2)

Lmax = 120.00 mm

But L/d ratio should not more than 10 times. That means always the length of punch keep in

normal condition 55 – 60 mm

Length of piercing punch L = 55.00 mm

The dimension of piercing punch is (Ø8 x 55) mm

Design of pilot punch

If the strip is fed more or less than the pitch then it is going to affect the number of

components and also change the dimension of components.

To reduce the chance of misalignment of over feeding or underfeeding pilots are used.

Pilot position the strip and ensure proper positioning. It means that it registers the position of

strip. Pilot arrests all movements before punching.

Two types of pilots are used,

Spring load pilot

Fixed pilot

At least two pilots are necessary for proper piloting. For piloting must be a pre-pierced

hole. Fixed pilots are always used in a blanking punch. If the overfeed is more and there is a

eccentricity between axis of pierced hole and axis of pilot, due to wider opening in the die, the

component is bent but nothing happens in the pilot. Hence a fixed pilot is used in blanking

punch.

If the pilots are individual to position the strip they are spring loaded. The reason is

that, if fixed pilot is used due to overfeed or underfeed the eccentricity of axis between pierced

hole and pilot makes the pilot to enter at an angle and this results in a breakage of pilot or it

make a dent mark on the strip. Therefore spring load pilots are used when only piloting is to

be done.

The length of pilot is greater than the punch length as shown in figure. The bullet nose

is provided at the end of ensure the strip into its correct position. Surface of the pilot should be

highly polished to reduce the friction.

In general,

Diameter of pilot, dpilot = dpunch – 0.05 to 0.03 mm for low accuracies

dpilot = dpunch – 0.05 to 0.03 mm for high accuracies

A = 0.6t to 1t or minimum 2.5 mm

B = 3 to 5 mm or d/2 (whichever is greater)

Diameter of pilot punch = d - 3% of component thickness

= 8 - 0.03 x 2

= Ø7.94 mm

Diameter of pilot on die block = 2c + Diameter of pilot punch

= 2 x 0.06 + 7.94

= Ø8.06 mm

Length of pilot punch = Length of piercing punch (L) + 2.00 mm

= 57.00 mm

Design of blanking punch

The blanking aperture length = 70.00 - 2C

= 70.00 - 2 x 0.06

= 69.88 mm

The width of blanking punch = 30.00 - 2C

= 30.00 – 2 x 0.06

= 29.88 mm

Corner radius of punch = R – C

= 2.5 – 0.06

= 2.44 mm

Length of blanking punch = Length of piercing punch = 55.00 mm

The designed detail diagram of punches like piercing punch, piloting punch, oblong

piercing punch, notching punch and blanking punch has shown in the fig 5.3.9

Shut height = (Length of punch - 2) + Punch back plate thickness + die plate thickness + top

plate thickness + Bottom plate thickness

= (55.00 – 2.00) + 8.00 + 35.00 + 42.00 + 52.00

= 190.00 mm

Day height = (Length of punch - 2) + Punch back plate thickness + die plate thickness

= (55.00 – 2.00) + 8.00 + 35.00 = 96.00 mm

5.2 THEORETICAL DEFLECTION AND STRESS CALCULATION

5.2.1 DIE BLOCK

The mathematical analysis is greatly simplified assuming that the die block (die plate)

is considered to be as fixed beam. The shoe deflection is calculated using the strength of

material formula for fixed supported beam,





I = bh3/12 (moment of inertia) = 6.29 x 106 mm4

Where, b = length of bottom plate = 176 mm

h = thickness of bottom plate = 35 mm

Deflection, δ = (209419.3 x 2223) / (192 x 2.1 x 105 x 6.29 x 106)

= 9.26 µm

Stress, p = F/A


p = 209419.3 / (176 x 35)

= 14.8 N/mm2

= 1.48 x 107 N/m2

Fig 5.2.1 2d Diagram of Die Block for Theoretical Calculation

5.2.2 TOP HALF

Top half includes as for calculation and analysis purpose as top plate, punch back plate

and punch plate. The mathematical analysis is greatly simplified assuming that the bottom

plate is considered to be on parallels. The shoe deflection is calculated using the strength of

material formula,









= 4.97 µm

Stress, p = F/A


p = 209419.3 / (326 x 66)

= 43.7 N/mm2

= 9.73 x 106 N/m2

Fig 5.2.2 2d Diagram of Top Plate for Theoretical Calculation

5.2.3 BOTTOM PLATE

The mathematical analysis is greatly simplified assuming that the bottom plate is

considered to be on parallels. The shoe deflection is calculated using the strength of material

formula for parallels supported beam,



L = distance between parallel






= 5.26µm

Stress, p = F/A


p = 209419.3 / (326 x 52)

= 43.7 N/mm2

= 4.37 x 107 N/m2

Fig 5.2.3 2d Diagram Bottom Plate for Theoretical Calculation

5.2.4 STRIPPER PLATE

The mathematical analysis is simplified by assuming fixed stripper to be considered as

a fixed beam support The fixed stripper plate deflection and stress is calculated using the

strength of material formula,


Where, F = 10% to 20% of cutting force = 0.2 x 26177.41 kgf = 5235.48 kgf = 52354.8 N



I = bh3/12 (moment of inertia) = 1.17x 105 mm4

Where, b = length of stripper plate = 176 mm

h = thickness of stripper plate = 20 mm


= 9.26µm

Stress, p = F/A


p = 52354.8 / (176 x 20)

= 14.87 N/mm2

= 1.487 x 107 N/m2

Fig 5.2.4 2d Diagram Stripper Plate for Theoretical Calculation

Stripping force depends on many factors, including stock thickness, cutting perimeter,

physical properties of stock, punch clearance, stock lubrication and scrap allowance.

5.2.5 GUIDE PILLAR

First we can check the diameter of guide pillar by using standard formula as 1.1 to 1.3 time of

thickness of die plate.

The diameter of guide pillar = 1.1 to 1.3 x thickness of die plate

= 1.1 x 35 = 38.5 mm > 22 mm

Hence the guide pillar diameter is safe dimension.

The mathematical analysis is simplified assuming that the guide pillar as a cantilever

beam if the thrust force is high compared to vertical load. Here for cutting operation 80% of

cutting force is acting on vertically and 10 to 20 % of total cutting force only acting on side

thrust. So the side thrust is comparatively very less amount only acting on the guide pillar.

Therefore the side thrust may be neglected for this cutting operation. For this condition the

guide pillar is as consider as a one side is fixed and other end is free column construction,

From strength of material for column construction of one end is fixed and other end is

free type, crippling load as

P = π2 E I / 4 l2

Where E = 2.1 x 105 N / mm2

I = π d4 /64

d = 22 mm

l = 142 mm

P = 73872.53 N > 10000 N

The applying load is also within crippling load. Hence the applied load is safe for design.

Deflection, δ = P l / A E

= 11.022 µm

Stress, p = P / A

= 1.63e8 N/m2

Fig 5.2.5 2d Diagram Guide Pillar for Theoretical Calculation

5.2.6 PUNCHES

Piercing punch

The mathematical analysis is simplified assuming that the piercing punch as consider

as one end is fixed and compressive force is acting on other end. Here for cutting operation

(piercing operation) 80% of cutting force is acting on punch as compressive nature.

We know that the compressive force on the punch is equal to the shear force on sheet

metal.

Cutting force Compressive stress on piercing punch, Scp = -----------------------------------


Scp = 4 π d t Ss / π d2 = 4 t Ss /d

Where, t = thickness of sheet metal = 2mm

Ss = shear stress on sheet metal = 35 kgf/mm2

d = diameter of piercing punch = Ø8 mm

Scp = 3.50 x 108 N/m2

Deflection of piercing punch, δp = Pp L / Ap E

Where, δp = piercing punch deflection

Pp = Compressive force for piercing operation = 14074.32 N

L = Length of punch = 55 mm

Ap = Cross sectional area of piercing punch = 50.27 mm2

E = Modulus of rigidity = 2.1 x 105 N/mm2

δp = 9.15 µm

Fig 5.2.6a 2d Diagram Piercing Punch for Theoretical Calculation

Oblong piercing punch

The mathematical analysis is simplified assuming that the oblong piercing punch as

consider as one end is fixed and compressive force is acting on other end. Here for cutting

operation (oblong piercing operation) 80% of cutting force is acting on punch as compressive

nature.


metal.

Cutting force Compressive stress on oblong piercing punch, Sco = -----------------------------------


Here Cutting force for oblong hole piercing operation, Po = 27559.81 N

Cross sectional area of oblong piercing punch, Ao = 118.27 mm2

Modulus of elasticity, E = 2.1 x 105 N/mm2

Length of oblong hole piercing punch, L = 55 mm

Compressive stress on oblong piercing punch, Scp = 2.89 x 108 N/mm2

Deflection of oblong piercing punch, δo = Po L / Ao E

δo = 7.57 µm

Fig 5.2.6b 2d Diagram Oblong Piercing Punch for Theoretical Calculation

Notching punch

The mathematical analysis is simplified assuming that the notching punch as consider


(notching operation) 80% of cutting force is acting on punch as compressive nature.


metal.

Cutting force Compressive stress on notching punch, Scn = -----------------------------------

Cross sectional area of punchHere Cutting force for notching operation, Pn = 22158.40 N

Cross sectional area of notching punch, An = 70.95 mm2


Length of notching punch, L = 55 mm

Compressive stress on notching punch, Scn = 4.89 x 108 N/mm2

Deflection of notching punch, δn = Pn L / An E

δn = 15.02 µm

Compressive stress on modified notching stepped punch, Scn = 3.90 x 108 N/mm2

Deflection of modified notching stepped punch, δn = Pn L / An E

δn = 10.02 µm

Fig 5.2.6c 2d Diagram Notching Punch for Theoretical Calculation

Fig 5.2.6d 2d Diagram Modified Notching Punch for Theoretical CalculationBlanking punch

The mathematical analysis is simplified assuming that the blanking punch as consider


(blanking operation) 80% of cutting force is acting on punch as compressive nature.


metal.

Cutting force Compressive stress on blanking punch, Scn = -----------------------------------


Here Cutting force for blanking operation, Pb = 109599.84 N

Cross sectional area of blanking punch, Ab = 2094.64 mm2


Length of blanking punch, L = 55 mm

Compressive stress on blanking punch, Scb = 6.54x 107 N/mm2

Deflection of blanking punch, δb = Pb L / Ab E

δb = 1.75 µm

Fig 5.2.6e 2d Diagram Blanking Punch for Theoretical Calculation

5.3 PROGRESSIVE TOOLS DETAILED DRAWING

Fig 5.3.1 Detailed Drawing of Top Plate

Fig 5.3.2 Detailed Drawing of Bottom Plate

Fig 5.3.3 Detailed Drawing of Guide Pillar and Guide Bush

Fig 5.3.4 Detailed Drawing of Die Plate

Fig 5.3.5 Detailed Drawing of Punch Plate

Fig 5.3.6 Detailed Drawing of Punch Back Plate

Fig 5.3.7 Detailed Drawing of Stripper Plate

Fig 5.3.8 Detailed Drawing of Strip Guide Plate

Fig 5.3.9 Detailed Drawing of Punches Designed Diagram

Fig 5.3.10 Detailed Drawing of Automatic Stopper, Depression Screw, Spring Support

Pin, Fulcrum Pin and Finger Stopper

Fig 5.3.11 Detailed Drawing of Strip Support Plate and Shank

5.4 BILL OF MATERIALS OF PROGRESSIVE TOOLS

Table 5.4 Bill of Materials of Progressive Tools

Sl.No Qty DESCRIPTION MATERIAL F.M.S R.M.S REMARKS

01 1Nos TOP PLATE St-42 326X284X42 390X290X45 -

02 1Nos PUNCH BACK PLATE T110W2Cr95 252X176X8 255X180X15 52-55HRC

03 1Nos PUNCH PLATE St-42 252X176X16 255X180X20 -

04 1Nos STRIPPER PLATE St-42 252X180X20 255X180X25 -

05 1Nos STRIP GUIDE PLATE T110W2Cr95 302X50.9X6 305X55X10 52-55HRC

06 1Nos DIE BLOCK T110W2Cr1 252X176X35 255X180X40 58-60HRC

07 1Nos BOTTOM PLATE St-42 326X284X52 330X290X55 -

08 1Nos STRIP SUPPORT PLATE St-42 176X50X5 - -

09 2Nos PIERCING PUNCH T215Cr12W90 Ø10X55 Ø15X60 58-60HRC

10 2Nos PILOTS T110W2Cr1 Ø10X63 Ø10X70 52-55HRC

11 1Nos OBLONG PIERCING PUNCH T215Cr12W90 55X21X6 60X25X10 58-60HRC

12 2Nos NOTCHING PUNCH T215Cr12W90 55X16.25X4.5 60X20X10 58-60HRC

13 1Nos BLANKING PUNCH T215Cr12W90 70X55X30 75X60X35 58-60HRC

14 2Nos ALLEN SCREW STD M8X55 - -

15 1Nos LOCKING DOWEL STD Ø5X12 - -

16 2Nos LOCKING DOWEL STD Ø4X12 - -

17 3Nos FINGER STOPPER T110W2Cr1 80X10X5.9 85X15X10 52-55HRC

18 1Nos AUTOMATIC STOPPER M.C.S 125X22X10 130X25X15 52-55HRC

19 1Nos FULCRUM PIN T110W2Cr1 Ø3X130 - 52-55HRC

20 1Nos DEPRESSION SCREW St-42 Ø20X72 Ø25X75 -

21 4Nos GUIDE BUSH 17Mn1Cr95 Ø56X64 Ø60X70 58-60HRC

22 4Nos GUIDE PILLAR 17Mn1Cr95 Ø22X184 Ø25X190 52-55HRC


24 2Nos DOWEL STD Ø8X50 - -






30 1Nos SHANK St-42 Ø40X82.5 Ø45X85 -

31 4Nos C.S.K. SCREW STD M6X6 - -

32 1Nos SPRING SUPPORT PIN STD Ø8X80 Ø15X85 -

5.5 ASSEMBLED VIEW OF PROGRESSIVE TOOLS

Fig 5.5.1 Assembled View of Progressive Tools

Table 5.5 Tool Specifications

TOOL SPECFICATION

PRESS CAPACITY 40 TONES

TYPE OF PRESS MECHANICAL

PITCH 32.00 MM

STRIP WIDTH 74.00 MM

CLEARANCE 0.06 MM/SIDE

SHUT HEIGHT OF THE TOOL 190.00 MM

DAYLIGHT OF THE TOOL 96.00 MM

TYPE OF DIE SET REAR AND FRONT PILLER

TYPE OF STRIPPER SOLID TYPE

METHOD OF FEEDING MANUAL

TYPE OF STROKE FIXED

NO. OF SLIDE SINGLE ACTION

5.6 TOP HALF ASSEMBLED VIEW OF PROGRESSIVE TOOLS

Fig 5.6.2 Top Half Assembled View of Progressive Tools

5.7 BOTTOM HALF ASSEMBLED VIEW OF PROGRESSIVE TOOLS

Fig 5.6.3 Bottom Half Assembled View of Progressive Tools

CHAPTER 6

ANALYSIS6.1 INTRODUCTION

Finite Element Method is a numerical procedure for obtaining approximate solutions to

many of the problems encountered in the engineering analysis. FEM is one of the most

effective tools available in the industries to solve almost all kinds of engineering problems.

The major areas in which the FEM application is more pronounced are automotive industry,

aerospace industry and architectural applications for various analysis like static, modal, heat

transfer, soil and rock mechanics, hydraulics etc.,

The concept of solving in finite element method is a complex structure defining a

continuum is discretized into simple geometric shapes called elements. The properties and the

governing relationships are assumed over these elements and expressed mathematically in

terms of unknown values at specific points in the elements called nodes. An assembly process

is used to link the individual elements to the given system. When the effects of loads and

boundary conditions are considered, a set of linear or non-linear algebraic equations is

obtained. Solution of these equations gives the approximate behavior of the continuum or

structure.

6.2 OBJECTIVE

The objective of the analysis of the functional elements like die set (top plate and

bottom plate), die plate, punches (piercing punch, oblong punch, notching punch and blanking

punch), stripper plate, guide pillar and guide bush are include structural analysis to estimate

the deflection and stresses.

To carryout the analysis, 3D-Solid model of the all functional elements are modeled in

solid works 2003 software and imported to Ansys V10.0 software

6.3 APPROXIMATION

1. The material is assumed to be homogeneous and isotropic

2. Linear static analysis is considered for structural analysis

6.4 FINITE ELEMENT MODELING

In order to carryout the finite element analysis, as the principle the model is discretized

into finite number of elements. This is also a process in which a mathematical net or mesh is

generated. The geometric models (PARA) are imported into ANSYS. The element type

considered for structural analysis is solid 45. Each element type has a unique number and a

prefix that identifies the element category, the degree of freedom set which in turn implies the

discipline (structural, thermal, magnetic, electric) whether the element lies in two-dimensional

or three-dimensional space.

The types of elements chosen for analyses are given below. . The element

shown below is used for steady state structural analysis.

This element is used for

Steady state structural analysis with thermal loads along with the pressure loads

Modal analysis

Fig 6.4.1 Solid 45 3-D 8 Nodded Hexahedral Structural Solid Element

The element shown above is used for steady state structural analysis. SOLID 45 have a

quadrilateral displacement behavior and are well suited to model irregular meshes (such as

produced from various CAD/CAM systems). Eight nodes having three degrees of freedom at

each node define the element: Translations in the nodal x, y and z directions. The element also

has plasticity, creep, large deflection and large strain capabilities.

6.5 STRUCTURAL ANALYSIS

The functional elements like top half, die plate, stripper plate, guide pillar, guide bush,

punches like piercing punch, oblong piercing punch, notching punch and blanking punch are

subjected to steady state static structural loads and would lead to induction of stresses in the

functional elements. Hence it is required to study the deformations and stresses induced in the

model because of the static loads.

According to Vonmises a unit volume of material should have certain volume of

potential strain energy for transition of plastic state regardless of stress arrangement.

Vonmises stresses can be expressed as

(σ1 – σ 2) 2 + (σ2- σ3) 2 + (σ1- σ3) 2

σ = 2

To carryout the analysis, the element type used is SOLID 45 (structural element) and

meshed with Tetra elements and mapped elements. Material properties, boundary conditions

and various input data to be given are below.

Material Properties

Material properties such as modulus of elasticity, poison’s ratio are taken for the HDS

material for the analysis.

Modulus of elasticity, E = 2.1×1011 N/ m2

Poisson’s ratio, ν = 0.3 to 0.5

Boundary Conditions

Here Ux = UY = Uz, = 0. Thus all the functional elements like top half, die plate, stripper

plate, guide pillar, guide bush, punches (piercing punch, oblong piercing punch, notching

punch and blanking punch) and bottom plate are fully restricted to move in any of X, Y, Z

directions at specified place or nodes.

Loads

Load for the some function elements like top half, bottom plate and die plate are

applied on Fz positive direction of magnitude as 80% of cutting force as vertical. And for

punches like piercing punch, oblong piercing punch, notching punch and blanking punch are

applied on Fz positive direction of magnitude as calculated cutting force of that operation as

compressive load on surface. And also for guide pillar load applied is on Fx positive direction

of magnitude as 10 to 20% of cutting force as thrust load and F z positive direction of

magnitude of 80 to 90% of cutting force as vertical load. Element type: structural solid brick

8node 45. Application : structural analysis. The meshed and mesh with load and boundary

conditioned finite element model of functional elements are shown as follows,

Fig 6.5.1 Top Half Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.2 Die Plate Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.3 Stripper Plate Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.4 Guide Pillar Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.5Guide Bush Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.6 Blanking Punch Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.7 notching Punch Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.8 Oblong Piercing Punch Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.9 Piercing Punch Meshed and Mesh with Load and Boundary Conditioned FE Model

Fig 6.5.10 Bottom Plate Meshed and Mesh with Load and Boundary Conditioned FE Model

6.6 STRUCTURAL ANALYSIS RESULTS OF FUNCTIONAL ELEMENTS

Element type: solid brick 8node 45Material property:

Modulus of elasticity: 2.1 x 105 N/mm2

Poisson ratio : 0.3TOP HALF ANALYSIS

(a) Deflection (b) Stress PlotFig 6.6.1 Top Half Deflection (a) and Stress Plot (b)

Sl.No DescriptionThickness

mm

Analysis result Calculated valueDeflection

µmStress N/m2

Deflection µm

Stress N/m2

1 Top half 42+8+16 5.41 8.91e7 4.97 9.73e6

DIE PLATE ANALYSIS

(a) Deflection (b) Stress Plot Fig 6.6.2 Die Plate Deflection (A) and Stress Plot (b)


Mm


µmStress N/m2

Deflection µm

Stress N/m2

2 Die plate35 17.1 4.35e8 13.49 5.98e7

35 (80%) 13.6 3.44e8 13.49 5.98e7

STRIPPER PLATE ANALYSIS

(a) Deflection (b) Stress PlotFig 6.6.3 Stripper Plate Deflection (a) and Stress Plot (b)


mm


µmStress N/m2 Deflection

µmStress N/m2

3 Stripper plate16 30.4 4.53e8 18.08 1.42e718 16.2 2.28e8 12.69 1.26e720 11.4 1.96e8 9.26 1.14e7

GUIDE PILLAR ANALYSIS

(a) Deflection (b) Stress PlotFig 6.6.4 Guide Pillar Deflection (a) and Stress Plot (b)

Sl.No DescriptionSize

(Ø d X h)Mm


µmStress N/m2

Deflection µm

Stress N/m2

4 Guide pillar Ø 22 X 184 7.68 3.17e6 11.02 1.63e8

GUIDE BUSH ANALYSIS

(a) Deflection (b) Stress PlotFig 6.6.5 Guide Bush Deflection (a) and Stress Plot (b)

Sl.No Descriptionsize

(Ø d X h)Mm


µmStress N/m2

Deflection µm

Stress N/m2

5 Guide bush Ø56 X 64 4.80 3.25e7 - -

BLANKING PUNCH ANALYSIS

(a) Deflection (b) Stress PlotFig 6.6.6 Blanking Punch Deflection (a) and Stress Plot (b)


(L X W X T)Mm


µmStress N/m2

Deflection µm

Stress N/m2

6 Blanking punch 69.88 X 55 X 29.88 2.51 4.69e8 1.75 6.54e7

NOTCHING PUNCH ANALYSIS

(a) Deflection (b) Stress PlotFig 6.6.7 Notching Punch Deflection (a) and Stress Plot (b)

Sl.No

DescriptionSize

(L X W X T)mm


µmStress N/m2

Deflection µm

Stress N/m2

7 Notching punch 55 X 16.25 X 4.5 8.55 1.15e9 10.04 3.90e8

OBLONG PUNCH ANALYSIS

(a) Deflection (b) Stress Plot

Fig 6.6.8 Oblong Punch Deflection (a) and Stress Plot (b)


(L X W X T)mm


µmStress N/m2

Deflection µm

Stress N/m2

8 Oblong punch 55 X 21 X 6 8.43 1.37e9 7.57 2.89e8

PIERCING PUNCH ANALYSIS

(a) Deflection (b) Stress PlotFig 6.6.9 Piercing Punch Deflection (a) and Stress Plot (b)


(Ø d X h)mm


µmStress N/m2

Deflection µm

Stress N/m2

9 Piercing punch Ø 8 X 55 2.98 7.87e8 9.15 3.50e8

BOTTOM PLATE ANALYSIS

(a) Deflection (b) Stress PlotFig 6.6.10 Piercing Punch Deflection (a) and Stress Plot (b)


(L X W X T)mm


µmStress N/m2

Deflection µm

Stress N/m2

10 Bottom plate 326 X 256 X 52 4.06 1.13e8 5.26 4.37e7

REFERENCES

1. Seon-Bong Lee, Dong-Hwan Kim, Byung-Min Kim. ‘Development of optimal layout

design system in multihole blanking process.’ Journal of Materials Processing Technology

130–131 20 December 2002, Pages 2–8

2. Sung-Bo Sim, Sung-Taeg Lee, Chan-Ho Jang. ‘A study on the development of center

carrier type progressive die for U-bending part process.’ Journal of Materials Processing

Technology, Volumes 153–154, November 2004, Pages 1005–1010.

3. J.C. Choi, Chul Kim. ‘A compact and practical CAD/CAM system for the blanking or

piercing of irregular shaped-sheet metal products for progressive working.’ Journal of

Materials Processing Technology, Volume 110, Issue 1, March 2001 Pages 36–46.

4. H. S. Ismail, S. T. Chen and K. K. B. Hon. ‘Feature-Based Design of Progressive Press

Tools.’ International Journal of Machine Tools and Manufacture, Volume 36, Issue 3, March

1996, Pages 367-378.

5. Chul Kim, Y.S. Park, J.H. Kim, J.C. Choi. ‘A study on the development of computer-

aided process planning system for electric product with bending and piercing operations.’

Journal of Materials Processing Technology, Volume 130–131, 20 December 2002, Pages

626–631.

6. Sang B. Park. ‘An expert system of progressive die design for electron gun grid parts.’

Journal of Materials Processing Technology, Volume 88, Issues 1-3, 15 April 1999, Pages

216–221.

7. S. Kumar, R. Singh. ‘A low cost knowledge base system framework for progressive die

design.’ Journal of Materials Processing Technology, Volumes 153–154, 10 November 2004,

Pages 958–964.

8. Keun Park, Sang-Ryun Choi. ‘Finite element analysis for the lamination process of a

precision motor core using progressive stacking dies.’ Journal of Materials Processing

Technology, Volume 130–131, 20 December 2002, Pages 477–481.

9. P.H.Joshi. ‘press tools design and construction.’ McGraw-Hill Book Company, New York,

1972.

10. Dallas. D. B. ‘Progressive Die Design and Manufacture.’ McGraw-Hill Book Company,

New York, 1962.

11. Donaldson, Goold, Lecain. ‘Tool Design.’ Tata McGraw-Hill Publishing Company, New

York, 1988.

12. P.C. Sharma. ‘A Text-Book of Production Engineering.’ S. Chand & Company (Pvt) Ltd,

New Delhi, 1988.

Design and Optimization

Documents

Transcript of Design and Optimization