Main Full Report.docx

CHAPTER 1 1. INTRODUCTION

Processing steps involved in sheet metal industries, and increased knowledge in this process will help to improve the process and help in increase the production range of industry. Now a day’s sheet metal component are widely used in the day today life its ranging from household electrical component to big industries such as TV, camera, electrical ovens, computer as well as in automotive parts, aviation industries to reduce the cost as well as reduce the weight of the component and increase the performance of the product. Sheets with 0.2 to 20 mm thickness and higher are processed in industries depending on the requirement of customer or consumer or appl Forming processes like Piercing, Blanking, stamping and bending are very widely used in the making of sheet metal parts and it assembles different processes to manufacture sheet metal parts. Piercing and Blanking are metal shearing processes in which the input sheet material is sheared to a destination shape. In blanking, the blanked piece of material is the product and while in piercing, the material that is blanked is scrap while the remaining part of the strip is the product, as shown in the Figure. In this project, blanking and piercing are used to produce component. Blanking is one of the processes in which the sheet undergoes brutal deformation since the sheet metal is separated to have the slug and part. Industries involved in sheet metal manufacturing shear cutting methods are widely used for high and low cost production. Shear cutting process is more advantages over the other conventional metal or sheet metal cutting operation. Sheet metal cutting operation is common in most of the Citation.

1.1 Types of Dies

The theory of sheet metal behavior kept as a backbone for the development of various kinds of dies which are differentiable through their function. In some of the dies, the sheet metal should be 1

cut off from the strip and the remaining part is removed as a scrap. In some other dies, the complete part is finished within the single station. According to their construction and functions the die is divided into following groups [1]. 1.2 Compound Dies The die which undergone to more than two cutting operations like blanking and perforating etc. can be performed continuously in a single stroke. In compound die, the upper punch is connected to the ram comes in constant with metal and pierces the hold. This punch is moving downward, the springs keep on compressing and after certain limit the lower punch moves upward and blanks the outer portion. Here, the whole operation is performed at single station, it produces accurate result but the die design is complicated 1.3 Combination Dies The die which undergone the cutting and forming operations are combined and carried out in a single operation. First blank is prepared in the die and then it is held by pressure pads and drawn. All this is achieved entirely within the die assembly by use of cam actuated punch and die members or by designing the die for use on a double action press which has two independent rams or slides on moving inside another. 1.4 Progressive Dies In progressive dies, the work pieces move from the first station to successive which carries variable operations, to be performed in individual station. Each stations works in series manner and the work piece is placed in stock till at the end of station which cuts off finished piece. End of the each stroke, the stock is moving towards by one station and the complete work piece is constructed in a single stroke of ram. It can be designed for complicated operations of bending, forming etc. In these dies, indexing at every station is very important and therefore accuracy is not much. However, it is simple in design. 1.5 Die Construction The die set is the primary portion of every die construction. It made up of upper die and lower die both are machined in parallel in size. The portion of the die is provided with the shank which is used to clamp in the ram of the press. Both the upper die and lower die are aligned with the guide 2

pins. They are firmly attached to the stripper and the upper die is equipped with the bushings into which these pins slip-fit. The die blocks are mounted in the lower die in which they are attached through the die buttons. The punch plate is mounted on the upper shoe in which same manner as the die block. It holds all the punches which are perforated the sheet with the help of die at the bottom. While doing the punching operations, the punches can be prevented from the cracks by the spring loaded stripper plate. The stripper plate is held in the top plate with an offset location of forces of springs by means of guide pins. This die set is the combination of two die set. The upper die set is rectangular in shape with four post die set. The lower die set is rectangular in shape with open die set which is used for simple parts in larger quantities. 1 Materials Used In Die The die set is made up of Aluminium – Silicon alloy by replacing the tool steel material which enhance the high ductility and high hardness level. This material is suggested for light weight of the die and it tends to deforms while the thrust force is applied, regain its original shape. However it is good corrosion resistance. It is able to sustain up to 10 bar pressure which is applied by the hydraulic press [2]. Table – 1: Die components materials Sl. No Die parts Material used Young’s modulus (N/mm²) Density g/cm³ 1 Punches 14C6 2.1 x 10⁵ 2 Die 14C6 2.1 x 10⁵ 3 Top & bottom plate LM6 Alloy 72 x 10³ 2.65 4 Guide pin & bushes LM6 Alloy 72 x 10³ 2.65 5 Shank LM6 Alloy 72 x 10³ 2.65 6 Guide supporter LM6 Alloy 72 x 10³ 2.65 7 Punch plate LM6 Alloy 72 x 10³ 2.6.

Fig -1.1: Blanking & Piercing

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1.6 Problem Statement The aim of this project is to reduce cycle time of existing process of milling, blanking and drilling operation for component. These all operations need be combined in a single setup of die punch with a proper tool design. The monthly volume of component is 4000 to 6000 nos. Hence company needs cycle time reduction and cost reduction as well on these hinges to meet global competition. The existing cycle time of operations is approximately 4 minutes. After the implementation of this project we can expect this to 30 secs.

Fig -1.2 : 3D model of die punch

1.7 From Sheet Metal Forming Processes and Die Design

Blanking and punching dies are known as cutting dies. They may be simple, combination, or compound. A blanking die is generally cheaper to make and faster in operation than a trim die. A single blanking die can produce either a right or left part, while two trim dies are needed for trimming: one die for right-hand parts and another die for left-hand parts. When a sheared flat blank drops through the die block (die shoe) it piles up on top of the bolster plate. If the blank goes through the hole, it is called a drop-blank die. A die in which the sheared blank returns upward is called a return-blank die. Return-blank dies are slower in operation and cost more to build than drop-blank dies.

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A punching die is a typical single-station die design for production holes made in flat stock, which may be manually or automatically fed. The stock guide keeps the stock on a straight path through the die. The amount of stock travel is controlled by the method of feeding, by stops of various designs, or by direct or indirect piloting. A combination die is a single-station die in which both cutting and non-cutting operations are accomplished at one press stroke. 1.8 Blanking Services Information

Show all Blanking Services Providers Blanking is a manufacturing process where a punch and die are used to remove blanks in preparation for processing and finishing. This cutting process is done by applying a shearing force to a material sheet. In blanking, the removed piece is the desired workpiece and is referred to as a blank. The process can be used to cut out almost any 2D shape and is commonly used for simple workpieces with simple geometry. Due to the shearing force, the pieces often need a finishing to smooth out burrs.

Fig 1.3: Blanking process. Blanking workpiece.

1.9 Image Credit: custompartsnet.com | metalstampingdies.com

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The machinery consists of a blanking press, sheet metal, blanking punch, and blanking die. The dies used can be a generic shape or customized for a specific design but instead of having a cavity, it has a cutout in the shape of the desired workpiece. The sheet metal is placed over the die and below the punch tool (typically 10-20% of the material thickness clearance), which is also in the desired shape of the workpiece. The tools are made from a steel or carbide and pare hydraulically powered. The hydraulic press drives the punch downwards at a high speed into the sheet, the metal quickly bends and then fractures. The created blank falls into the gap of the die.

1.10 Types

Fine or Precision blanking - Produces metal pieces with tight tolerances of +/- 0.0003. The blank is sheared from the sheet using three separate forces. The first is a downward holding force applied to the top of the sheet, the second force is applied under the sheet, opposite the punch. The two forces act together to reduce the bending of the sheet for flatter blanks. The third force is the blanking punch impacting the sheet and shearing the blank into the die opening. This technique produces a part with a flatter part with smoother edges so higher quality parts that do not require finishing can be produced. The clearance is around 0.001 inches and the blanking is performed at slower speeds. The additional equipment and tooling makes this process more expensive so it is better suited for high volume productions.

Fig 1.4: Fine or precision blanking. 1.11 Material

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The material is usually a sheet but it may also be in rolls. 

Sheet Metal- Metal components can be formed using a punch. The punch is usually the upper member of the complete die assembly and is mounted on the slide or in a die set for alignment (except in the inverted die).



Plastic- Plastic pieces are usually scrap materials, such as tails, molding flash and slugs from bottles, which need to be removed from the workpiece.



Paper, board, PP- or PE- foil- Paper and related products such as those used for labels can be self-adhesive or plastic laminated. Service Considerations When selecting a blanking service provider there are several specifications to consider.



Who will the material? The customer or the service company?



Does the service company custom-produce dies?



Do they offer discounts for large volume orders? Much of the cost associated with blanking is setting up and calibrating the equipment.



Does the service company provide additional finishing services such as removing burrs, stamping, and polishing? This video compares several metal stamping processes.

1.12 U-Profile Bend Dies

Fig. 10.1 illustrates a simple die for bending a U-profile. In this example, the blank of length L, width b, and thickness T, is positioned on the die (1) between stop pins (11). The die (1) is mounted on the lower plate (3) in the conventional position. The punch (2) is attached to the punch holder (4), which is fitted a shank (6) for that purpose, to the ram of the press. The pressure pad (10) applies pressure to the blank so that as the punch pushes the blank into the die, the workpiece is formed by a single stroke of the press. The bent workpiece is ejected from the die by the pressure pad mechanism (a) when the press ram retracts. For bending workpieces of small dimensions and thin material, the punches and dies are made from a single block of metal. 7

Figure 10.1: Simple bending die.

Stripper plates remove the material strip from around blanking and piercing punches. Severe adhesion of strip to punches is characteristic of the die cutting process. Because of their low cost, solid strippers are the most frequently used type, particularly when running strip stock. Spring strippers, though more complex, should be used when the following conditions are present: 1. When perfectly flat, accurate blanks are required, spring strippers flatten the sheet before cutting begins. 2. When very thin material is to be blanked or pierced, to prevent uneven fracture and rounded blank edges. 3. When parts are to be pressed from waste strip left over from other operations, spring strippers provide good visibility to the operator for gaging purposes. 4. When stripping occurs immediately, small punches are not as subject to breakage. 5. When conducting secondary operations, such as in piercing dies, increased visibility provided by spring strippers allows faster loading of work and increased production.

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Stripper plates may be made of cold-rolled steel if they are not to be machined except for holes. When machining must be applied to clear gages, the plates should be made of machine steel, which is not as subject to distortion. This chapter describes numerous methods of applying stripper plates and their components. These methods further explain Step 10 in Chapter 5 14 Steps to Design a Die.

1.13 Presses (metalworking) Information

Show all Presses (metalworking) Manufacturers

Fig 1.5: Image Credit: Savage Engineering, Inc.

Industrial presses (metalworking) use a ram to shear, punch, form, or assemble metals or other materials by cutting, shaping, or using dies attached to slides.

1.14 Types of Presses (Metalworking)

Selecting industrial presses (metalworking) requires an understanding of equipment types. Some examples include:

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

Die cutting machines are used in the manual conversion of web or sheet materials such as woven cloth, non-woven textiles or rubber sheeting. Clicker presses and rotary die cutter are designed for die cutting operations.



Forming machines are used to form or bend metal sheets and plates. Shop presses are suitable for general-purpose applications. Wire forming presses are designed or suitable for wire forming or wire bending operations.



Punch presses are machines that use a set of dies under pressure to put holes into materials to shape metal parts.



Stamping presses operate stamping and other types of dies by powering the opening and closing of die sets, which are composed of punches and die blocks. Die sets assemble upper and lower die shoes, guide pins, bushings, and punch and die holders. Stamping presses fabricate components from sheet metal via blanking, piercing or punching, forming, bending and drawing.



Turret presses are industrial presses that have an open frame and a turret with multiple punches. Turret punch presses, typically numerically controlled, are used mainly to perform shearing operations. Industrial presses such as the turret press can allow metal to be weaved together by creating tabs with a lanced dimple that, when mated, falls into another dimple of an opposing tab. Depending on the application, the tool can eliminate welding or other joining processes. Specifications

Machines differ in terms of features and specifications. Operational method, technology, force and pressure specifications, and speed and stroke specifications are important parameters to consider when selecting industrial presses. Some industrial presses are driven by mechanical power, such as the mechanical punch press, which can be driven by flywheels, cranks, or clutches.

1.15 Standards

Nas982 - hot forming, sizing, and straightening press specification bs en 14673 - safety of machinery - safety requirements for hydraulically powered open die hot forging presses for the forging of steel and non-ferrous metals

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saa as 4024.3001 - safety of machinery part 3001: materials forming and shearing - mechanical power presses saa as 4024.3002 - safety of machinery part 3002: materials forming and shearing - hydraulic power presses Help with presses (metalworking) specifications: 1.6 Press Type

Press Type Your

choices

are... Clinching machines use a cold forming process to fasten sheet metal components together. During the clinching process, a punch forces Clinching

the two layers of sheet metal into a die, creating a permanent

Machine

connection. Clinching machines are an economical alternative to riveting and welding operations. Clinching is commonly used in the HVAC, automotive, manufacturing and housing industries. Die cutting presses are used in the manual conversion of web or

Die

Cutting

Machine

sheet materials such as woven cloth, non-woven textiles, and rubber sheeting. Clicker presses and rotary die cutters are designed for the die cutting of web or sheet materials.

Forming

and

Bending Machine

Forming machines are designed to form or bend metal sheets or plates. Hydroforming presses are designed to process metal source-material

Hydroforming Press

sheets, plates or tubes. The resulting parts are typically of higher quality than those produced from traditional stamping methods. Compared

to

stamping,

finished

parts from

a

hydroforming process often offer better strength, geometry, surface

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finish,

aerodynamics,

and

other

desired

performance

characteristics. Low-drag and visually-pleasing automobile hoods are one example of a hydroform-pressed component. Punch Press

Punch presses are used for punching, blanking, piercing, nibbling, tab forming, stamping, press forming, embossing and slug cutting. Shop presses are designed for general-purpose job shop operations.

Shop Press

They include arbor presses, ironworkers, metal shears, and press brakes.

Sheet

Metal

Equipment

Sheet metal equipment is designed to fabricate components from sheet metal. These industrial presses are capable of stamping, blanking, punching, bending, spinning, stretching, or nibbling. Stamping

Stamping Press

presses fabricate

components

from

sheet

metal

using blanking, piercing or punching, forming, bending and drawing.

Wire Forming

Specialty

Wire forming presses are designed or suitable for wire forming or wire bending operations. Other unlisted, specialized, or proprietary presses or forming machine tools. All products with ANY of the selected attributes will be returned as

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matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

Thermal presses or machines are suitable for elevated temperature operations such as hot stamping, hot forming, or diffusion bonding Hot Press

of metals. The metal or material is heated to a plastic state, allowing a level of deformation that would cause cracking or excessive residual stress in a cold forming operation.

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"Required" and "Must Not Have" criteria limit returned matches as Search Logic:

specified. Products with optional attributes will be returned for either choice.

Back to Top Press / Operation Type

Operation Your

choices

are... Bending

Presses can produce simple bends of at least 90 degrees or more. Presses are suitable for blanking operations. Blanking is the cutting

Blanking

of a part from sheet stock. Presses are designed to cut gears or splines by forcing a broach or

Broaching Cut-off

multi-toothed cutter along the internal or external surface of a part. /

Shearing

Presses are designed for cutting-off or shearing stock of various thicknesses. Presses can perform deep drawing, stretching, and other press-

Deep Drawing

forming operations. Presses are suitable for fine blanking operations. Fine blanking cuts a part from sheet stock, while maintaining much higher tolerances

Fine Blanking

than

conventional

blanking. A

stiffener

and

high-precision

machining are required. Extrusion

Presses form parts such as tin paste tubes through extrusion or back-

Forming

extrusion operations.

Marking Coining

/

Presses can perform marking or coining operations. Marking or coining results in a local change in cross-section. 13

Presses perform nibbling operations. Nibbling is a punch-cutting process where irregularly-shaped holes are formed via a series of Nibbling

rapid punch hits or strokes across the part. Nibbling can also refer to presses or shearing machines that cut contours in a sheet with a series of small or scissors-like cuts.

Piercing / Hole

Presses

can

Punching

operations.

perform piercing,

perforating, or

hole-punching

Presses can perform stamping, embossing, or other shallow pressPress Forming / Embossing

forming operations. These presses or machines may also be capable of simple bending or forming operations such as tab or louver forming. Embossing is used to form beads, stiffen ribs, or locate features.

Side Punching / Notching

Notching may also refer to the removal of corners or outer edges from a sheet or part.

Straightening / Flattening Tube

Presses can side-punch, notch, or pierce a tube or component.

Sheet

Forming Other

Presses can straighten or flatten sheet metal, plates, or other stock. Presses can form tube sheets for boiler or heat exchanger applications. Other unlisted, specialized, or proprietary press operations for forming or cutting materials. All products with ANY of the selected attributes will be returned as

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matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

Back to Top Technology

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Press Technology Drive / Actuation Your choices are... Air / Pneumatic

The press is driven or powered by a pneumatic cylinder. The press is driven or powered by a hydraulic cylinder.

Hydraulic

Hydraulic presses can generate extremely high forces to form metals or other materials. Hydro-mechanical presses are driven by a hydraulic cylinder

Hydro-mechanical

or hydraulic motor. The press is driven by a rotary motor through a screw, toggle,

Mechanical Servo

(Driven

lever, or other mechanism. /

Control)

The press or machine is servo-controlled or directly driven by a servo motor. The press is driven or powered by hand, or with manual force

Manual

that is magnified with screw, lever, or other mechanism.

Other

Other unlisted, specialized, or proprietary technologies. All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not

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Frame Type

&

Orientation: Your choices are... Bench Mounted

Smaller presses or forming machines can be mounted on a bench, stand, or pedestal. Typically bench-mounted presses are

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used in shop operations or for the preparation of laboratory samples. Open back presses have a one-piece frame with an opening at Open Back (OBI / OBS)

the back between the two gap uprights. This opening is typically slightly more than the left-to-right dimension of the slide flange. Open back inclinable (OBI) gap presses are very common. OBS refers to open back stationary presses.

C-Frame

/

Gap

Frame

Gap frame, C-frame, or open-fronted presses have a C-shaped configuration where the front and side of the press are open for easy access.

Column (4 Post) /

Four-post or column presses have a frame with posts at the

Straight-Side

corners.

Inclined / Inclinable

Inclined or inclinable presses tilt back or remain tilted to facilitate the removal of punched parts. H-frame presses consist of structural steel shapes (I-beams and angle iron) that are welded or bolted into an H-shape.

H-Frame

Additional beams are attached to provide floor mounts and cylinder support across the top. The central beam holds a mounting plate for tooling, vises, or clamps. On sliding-bed presses, the bed or bolster plate slides in-and-

Sliding Bed / Roll

out from under the ram for the placement and set up of the

Frame

workpiece. Roll frame presses have a stationary bed that supports a movable frame which is mounted on rollers.

Other

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Other unlisted, specialized, or proprietary frame types or orientations. All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not

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limit the search criteria for this question; products with all attribute options will be returned as matches.

Back to Top Force / Pressure Specifications Pressure is applicable to isostatic presses.

The operating press load required to cut or form a part or rivet assembly Capacity Operating Force:

/

during production. The rated capacity of a press is the ton pressure, which the slide or ram will safely exert at the bottom of the stroke while working within the range of the press. In a mechanical press, the capacity is determined by the bending capacity of the main shaft (crank, toggle, or eccentric shaft).

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Pressure

Search Logic:

User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria.

Pressure is the hydraulic force per unit area exerted by the industrial press upon the piece being worked. User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria.

Back to Top Speed & Stroke Specifications

Stroke:

Stroke is the ram travel from top dead center (TDC) to bottom dead center (BDC).

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Search

User may specify either, both, or neither of the "At Least" and "No More

Logic:

Than" values. Products returned as matches will meet all specified criteria.

Stroke

Stroke speed is the linear speed of the slide or ram during pressing or ram

Speed:

advancement steps.

Search

User may specify either, both, or neither of the "At Least" and "No More

Logic:

Than" values. Products returned as matches will meet all specified criteria.

The number of forming, punching operations, or units produced per time; and usually stated as the number of strokes, hits, cut-outs, cycles or hits per Rate:

minute that the machine is capable of performing. In a progressive or indexing on complex parts, the total production rate will depend on the number of steps or operations required to fabricate the complete part.

Search

User may specify either, both, or neither of the "At Least" and "No More

Logic:

Than" values. Products returned as matches will meet all specified criteria.

The number stations in an indexing, automatic press, such as a turret punch Stations:

press. The turret holds several different tool sets that rotate into place allowing the punch press to perform a series of operations for the production of complex parts.

Search

User may specify either, both, or neither of the "At Least" and "No More

Logic:

Than" values. Products returned as matches will meet all specified criteria.

Back to Top Special Features

Automation / Control:

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Your choices are... Manual (Footswitch / Pendant / Pushbutton)

The press is controlled manually through an operator interface device such as a footswitch, pendant, or push-button controls. The press or forming machine automatically loads parts into

Automatic / Indexing

the system and operates without operator intervention. The machine changes or adjusts tooling and other parameters, such as speed or applied load, in a pre-programmed manner. A CNC controller is used to program and perform a sequence

CNC Control

of operations on the press. A PLC controller is used to program and perform a sequence

PLC Controller Windows®

/

of operations on the press. PC

Control Other

The press or forming machine is controlled or programmed through a PC interface. Other unlisted, specialized, or proprietary automation or control technology. All products with ANY of the selected attributes will be

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returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

Features Your choices are... Presses have two-or-more slides for multiple, independent, parallel movements. Double-acting presses are used in draw Double / Triple Acting

forming processes because they provide a way to hold down or clamp the rim of the sheet. There are two types: mechanical and hydraulic. With mechanical double-acting presses, one 19

slide is operated by crankshaft; the outer or blank holder slide, which dwells during the drawing process, is usually operated by a toggle mechanism or cams. Hydraulic double-acting presses have multiple cylinders to drive the different slides. Triple-acting presses typically have a lower slide mechanism with an upward or opposing motion. Multi-station presses use rotary tooling or turrets, progressive dies, transfer systems, or other multi-station die sets. Rotary turret punch presses are automatic machines that index the Multi-Station (Rotary

material and select the required tool from the rotary tool

Turret)

holding

device or

turret, usually

by

computer

control. Depending on the program selected, turret punch presses

are used for

piercing,

blanking

and

forming

workpieces. Multi-tool systems consist of multiple tool turrets within a

Multi-Tool

single turret. They provide automatic indexing. Coil feeders and web feeders are integral or optional sub-

Coil / Web Feeder

systems

that

are

used

to

feed sheet-metal

coil

stock, or cut strips and other web materials. Integral Cut-Off Shear

Integral Laser Cutter

/

Machines provide the integral shearing or cut-off of sheet or web materials, or excess scrap material. Examples include a flying shear on a rolling mill machine. Presses feature an integral laser-cutting system to provide additional fabrication capabilities. Equipment is

Laboratory

as process

designed

parameter

sample preparation.

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for laboratory

applications such

studies, material

development, or

Load / Press Monitor

Presses have sensors and monitoring systems for detecting the load and thickness of compacted materials. Presses are complete manufacturing cells, production lines, or turnkey systems with material handlers, degreasing

Manufacturing (Loader / Stacker)

Cell

units, or other sub-systems for fabricating parts from coils, metal sheets, or web materials. Alternatively, these press or stamping

systems

may

have loading,

stacking,

or

destacking features for handling sheets, parts, or materials. Other

Other unlisted, specialized, or proprietary features. All products with ANY of the selected attributes will be

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returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

1.17 SHEARING Shearing is a cutting operation used to remove a blank of required dimensions from a large sheet. To understand the shearing mechanism, consider a metal being sheared between a punch and a die, Fig 5.1 Typical features of the sheet and the slug are also shown in this figure. As can be seen that cut edges are neither smooth nor perpendicular to the plane of the sheet.

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Fig 1.6: (a) Shearing with a punch and die (b) features of a punched hole and (c) features of the slug. Shearing starts as the punch presses against the sheet metal. At first, cracks form in the sheet on both the top and bottom edges (marked T and T', in the figure). As the punch descends further, these cracks grow and eventually meet each other and the slug separates from the sheet. A close look at the fractured surfaces will revel that these are quite rough and shiny; rough because of the cracks formed earlier, and shiny because of the contact and rubbing of the sheared edge against the walls of the die. The clearance between the punch and the die plays an important role in the determination of the shape and quality of the sheared ege. There is an optimum range for the clearance, which is 2 to 10% of the sheet thickness, for the best results. If the clearance increases beyond this, the material tends to be pulled into the die and the edges of the sheared zone become rougher. The ratio of the shining (burnished) area to the rough area on the sheared edge decreases with increasing clearance and sheet thickness. The quality of sheared edge is also affected by punch speed; greater the punch speed better the edge quality. 23

1.18 Shearing Operations

For general purpose shearing work, straight line shears are used. as shown in Fig 5.2, small pieces (A, B, C, D……….) may be cut from a large sheet.

Shearing may also be done between a punch and die, as shown in Fig 5.1. The shearing operations make which use of a die, include punching, blanking, piercing, notching, trimming, and nibbling.

1.19 Punching/Blanking

Punching or blanking is a process in which the punch removes a portion of material from the larger piece or a strip of sheet metal. If the small removed piece is discarded, the operation is called punching, whereas if the small removed piece is the useful part and the rest is scrap, the operation is called blanking, see Fig 5.3. Fig 5.3 Comparison of basic stamping operations. In punching, the metal inside the part is removed; in blanking, the metal around the part is removed. A typical setup used for blanking is shown in Fig 5.4.

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Fig 1.7 : Blanking punch and die. The clearance between the die and punch can be determined as c = 0.003 t. t where t is the sheet thickness and t is the shear strength of sheet material. For blanking operation, die size = blank size, and the punch is made smaller, by considering the clearance. The maximum force, P required to be exerted by the punch to shear out a blank from the sheet can be estimated as P = t. L. t where t is the sheet thickness, L is the total length sheared (such as the perimeter of hole), and t is the shear strength of the sheet material. Stripping force. Two actions take place in the punching process – punching and stripping. Stripping means extracting the punch. A stripping force develops due to the spring back (or resiliency) of the punched material that grips the punch. This force is generally expressed as a percentage of the force required to punch the hole, although it varies with the type of material

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being punched and the amount of clearance between the cutting edges. The following simple empirical relation can be used to find this force SF = 0.02 L.t where SF = stripping force, kN L = length of cut, mm t = thickness of material, mm Example: A circular blank of 30 mm diameter is to be cut from 2 mm thick 0.1 C steel sheet. Determine the die and punch sizes. Also estimate the punch force and the stripping force needed. You may assume the following for the steel : Tensile strength: 410 MPa ; shear strength : 310 MPa Solution:- For cutting a blank, die size = blank size \ Die size = 30m Clearance = 0.003 x t x t = 0.003 x 2 x 310 = 1.86 mm Punch size = blank size – 2 clearance = 30 – 2 x 1.86 = 26.28 mm Punch force needed = L. t. p = p x 30 x 2 x 310 = 58.5 kN Stripping force needed = 0.02 L.t = 0.02 x p x 30 x 2 = 3.77 kN Piercing: It is a process by which a hole is cut (or torn) in metal. It is different from punching in that piercing does not generate a slug. Instead, the metal is pushed back to form a jagged flange on the back side of the hole. 26

A pierced hole looks somewhat like a bullet hole in a sheet of meta

1.20 Trimming:

When parts are produced by die casting or drop forging, a small amount of extra metal gets spread out at the parting plane. This extra metal, called flash, is cut – off before the part is used, by an operation called trimming. The operation is very similar to blanking and the dies used are also similar to blanking dies. The presses used for trimming have, however, relatively larger table.

1.21 Notching:

It is an operation in which a specified small amount of metal is cut from a blank. It is different from punching in the sense that in notching cutting line of the slug formed must touch one edge of the blank or strip. A notch can be made in any shape. The purpose of notching is generally to release metal for fitting up.

1.22 Nibbling:

Nibbling is variation of notching, with overlapping notches being cut into the metal. The operation may be resorted to produce any desired shape, for example flanges, collars, etc. 1.23 Perforating:

Perforating is an operation is which a number of uniformly spaced holes are punched in a sheet of metal. The holes may be of any size or shape. They usually cover the entire sheet of metal. DIFFERENCE BETWEEN BLANKING, PUNCHING & PIERCING IN SHEET METAL 27

Blanking, Punching and piercing are sheet metal operations in which punch & Die are used to give shape to sheet metal parts. All these are shearing operations that can be done on CNC punching machine and on hydraulic press. Blanking is a process in which the punch operation removes a final product from a larger piece of sheet metal.

Fig: 1.8: Punching is a material removal process Punching is a material removal process in which the punch operation removes material from a final piece of sheet metal.

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Fig: 1.9: Piercing is process Piercing is process in which punch operation cuts a hole / material by tearing operation from a final piece of sheet metal. Piercing is a blanking operation

Fig: 1.10: Piercing is process 1.24 Metal-Cutting Process 29

Metal cutting is a process used for separating a piece of material of predetermined shape and size from the remaining portion of a strip or sheet of metal. It is one of the most extensively used processes throughout die and sheet-metal work. It consists of several different material-parting operations, such a piercing, perforating, shearing, notching, cutoff, and blanking. In blanking, the piece is cut off from the sheet, and it becomes a finished part. In piercing, the cutout portion is scrap which gets disposed off while the product part travels on through the remainder of the die. The terminology is different here, though both processes are basically the same and therefore belong to the same category, which is the process of metal cutting (Fig. 6-1).

The actual task of cutting is subject to many concerns. The quality of surface of the cut, condition of the remaining part, straightness of the edge, amount of burr, dimensional stability-all these are quite complex areas of interest, well known to those involved in sheet-metal work. Most of these concerns are based upon the condition of the tooling and its geometry, material thickness per metal-cutting clearance, material composition, amount of press force, accurate locating under proper tooling, and a host of additional minor criteria. These all may affect the production of thousands and thousands of metal-stamped part

CHAPTER 2 2. DESIGN OF DIE PARTS

Deflection and stress calculation Let us assumed to be a SSB beam which are mounted through four corners in the punch plate. It is loaded in the centre of the plate and their deflection should be. δ = ----------------------------------- ⑬ 30

Where, F = 80% of the cutting and forming forces = 2666.752 N L is the beam frame distance = 150 mm Young’s modulus (E) = 72 x 10³ N/mm² where, b = 200 mm (width of the plate) h = 32 mm (height of the plate) I = 860160 mm⁴ δ = 0.0004 mm < 0.025 mm σ = F/A = 0.4166 N/mm² The stress applied to the punch plate is 0.4166 N/mm² which is much less than 160 N/mm². Hence, the design is safe. 3.5 Guide Pins and Bushes Guide pins and bushes are made up of aluminium silicon alloy (LM6) which is used to align the punches and the die block. It attached between the top plate and stripper plate. 2.1 Buckling for guide pins

The guide pins materials are made up of LM6 alloy having a tensile strength of 160 N/mm² and their young’s modulus is 72x10³ N/mm². = 2l for one side is fixed and other side is set free. l = 146 mm 31

I = ------------------------------- ⑭ D = 22 mm I = 1165.68 mm⁴ A = 379.94 mm² S.R = / ------------------------------ ⑮ = = Radius of gyration ----------------------------- ⑯ = 20 S.R = 17.6 = Slenderness ratio T.S.R = = Transition slenderness ratio -------------- ⑰ T.S.R = 94.2 mm Here, the Johnson equation should be applied for critical buckling load. Since, the S.R ratio is lesser than that of T.S.R [7]. --------------------- ⑱ = 2166.6 N > critical load Hence the structure is safe. Load per pillar = 2166.6/4 = 541.65 N / pillar

2,2 Punch

The punches are mounted in the punch plate which is made up of plain carbon steel 14C6. The lengths of the punches 32

are properly quoted for the die performance. If the punches are having too much length, the compressive stress become excessive which results in tip breakage. The lengths of the punches are calculated from the Euler’s formula. The critical force is calculated through one is fixed and other end set as free [7]. ---------------------------------- (19) The length of the punches are calculated by -------------------------------- (20) D = dia. of the punch = 7.5 mm This shows that the length of the punch which is safe and it can perform without failure

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Fig -2.1: Component Model (Male and Female part)

Fig -2.3: 2D Drawing of die punch assembly

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Fig-2.4: Fatigue characteristics of tool stee Details

Specifications

Material

St-37

Thickness

6mm

Shear strength

320-350N/mm2

Tensile strength

370-450N/mm2

Table -1: Material Properties of component

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Property

Value

Units

Young’s Modulus

210000

N/mm²

0.3

-

modulus

7900

N/mm²

Mass density

7700

Kg/m³

Tensile strength

1736

N/mm²

Compressive Yield

2150

N/mm²

2150

N/mm²

1.04e.005

1/K

Thermal Conductivity

20

W/(m-K)

Specific Heat

460

J/(Kg-K)

Poisson’s Ratio Shear

strength Yield strength Expansio Thermal

n

Coefficient

Table -2: Material Properties of Die Punch material (D2 steel)

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CHAPTER 3 3. ANALYSIS IN ANSYS

In this project the analysis is carried out in Ansys 14.0 work bench. The punch is critical element in die punch, hence analysis is carried out on punches and the results are compared with theoretical calculations for validation. The material used for punches is D2 steel/HCHCr. It provide the stress result with the design cycle. It helps to predict the part to perform under load. Whenever the problem arise related to analysis, need a comprehensive analysis of the product is required [8]. 4.1 Analysis of Punches The analysis of punches are analyzed by the simulation express tool in which each punch is made fixture at the top of the punch and the load is applied at the tip of punch. The maximum shear load is occurred in the edges of the punch and deformed to maximum deflection which is calculated. The following figures show that the punches are deformed only at the tip. Analysis of Piercing punch

Fig- 3.1: Meshed model of Piercing punch.

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Fig- 3.2: Von-Mises stresses on piercing punch.

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Fig- 3.4: Total deformation of piercing punch. As shown in the analysis results, the minimum deformation is 0 mm at top of the punch and Maximum deformation is 0.2290 mm at the tip of punch. As shown in the analysis results in fig 8, the minimum life is 250 cycles and Maximum life is 100000 cycles

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Fig- 3.5: Fatigue life of piercing punch

Analysis of slotting punch

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Fig- 3.6: Meshed model of Slotting punch.

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Fig- 3.7: Total deformation of piercing punch. As shown in the analysis results, the minimum deformation is 0 mm at top of the punch and Maximum deformation is 0.1937 mm at the tip of punch.

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Fig-3.8: Von-Mises stresses on slotting punch. As shown in the analysis results, the minimum Von-Mises stress is 87.749 Mpa and Maximum Von-Mises stress is 1503Mpa.

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Fig- 3.9: Fatigue life of slotting punch. As shown in the analysis results, the minimum life is 1108 cycles and Maximum life is 1.15e7 cycles. Analysis of profile blanking punch Fig- 13:

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Fig- 3.10: Meshed model of profile cutting punch.

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Fig- 3.11: Total deformation of profile blanking punch. As shown in the analysis results, the minimum deformation is 0 mm at top of the punch and Maximum deformation is 0.01662 mm at the tip of punch.

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Fig- 3.12: Von-Mises stresses on profile blanking punch. As shown in the analysis results, the minimum Von-Mises stress is 4.33 Mpa and Maximum VonMises stress is 92.71Mpa.

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Fig- 3.13: Fatigue life of profile blanking punch As shown in the analysis results, the minimum life is 65000 cycles and Maximum life is 100000 cycles. 3.1 Results and Discussion First step is to decide the geometry of the Die-Punch tool, while having consideration on this; we need to take component which is selected for the optimization or alteration of manufacturing process. Here alternative method of manufacturing selected is punching; when a punching operation is selected first parameter under scanner is the amount of material required to be eliminated from the original raw material. Further in this process we need to decide the number of cycles for which this punch is been designed, here we are utilizing this punch for at least fifty thousand repeating punching operations, keeping in mind the monthly production of these parts around five thousand quantities. 48

Total Sl.No Description Deformation(mm)

Theoretical Ansys

Error (%)

1.

Piercing

0.2200

0.2290 3

0.1896

0.1937 2.1

0.01582

0.0166 4.8

Punch

2.

Slotting Punch

3.

Profile blanking Punch

Table -3: Fatigue life results.

Sl.No Description Fatigue life(cycles)

Theoretical Ansys

Error (%)

1.

Piercing

97000

100000

3

>1e6

>1e6

-

>1e6

>1e6

-

Punch

2.

Slotting Punch

3.

Profile

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blanking Punch

Sl.

Description Von-Mises Stress (N/mm2)

No Theoretical Ansys

Error (%)

1.

Piercing

1020

979

3.5

1480

1503

1.5

96

93

3.5

Punch

2.

Slotting Punch

3.

Profile blanking Punch

Maximum working stress for piercing punch is 927 N/mm², which is less than the Von-Mises stress 1020 N/mm².Hence punch will not fail under applied load of 59383N. Maximum working stress for Slotting punch is 400 N/mm², which is less than the Von-Mises stress 1480 N/mm².Hence punch will not fail under applied load of 358400N. Maximum working stress for profile blanking punch is 37 N/mm², which is less than the VonMises stress 96 N/mm².Hence punch will not fail under applied load of 226800N. Critical buckling load for piercing punch is 356029N.Actual load on piercing punch is 59383N, which is less than 356029N.Hence buckling will not occur.

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CHAPTER 4 CONCLUSION

In this project a die punch for blanking and piercing operation is designed and analysed for component. The theoretical calculations were done for calculating cutting force, tonnage required, fatigue life and stresses. The 3D models created in Catia-V5 and analysis is done on Ansys 14.0 workbench. The main objective of the project is to improve productivity and reduce production cost. The exiting cycle time for blanking and piercing operation is approximately four minutes which manufacturing cost is around six rupees. After implementation of this project we can expect the cycle time will be 30 to 40 secs and cost will be around 1.5 to 2 rupees.

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REFERENCES

1. Optimum selection of variable punch-die clearance to improve tool life in blanking nonsymmetric shapes Soumya Subramonian, Taylan Altan, Bogdan Ciocirlan, Craig Campbell. 2. Strain-controlled fatigue properties of steels and some simple approximations by M.L. Roessle, A. Fatemi. 3. Flanging using step die for improving fatigue strength of punched high strength steel sheet by Purwo Kadarno, Ken-ichiro Mori, Yohei Abe, Tatsuro Abe. 4. Computer aided blanking die design using CATIA by H. M. A. Hussain. 5. Study of the contribution of different effects induced by the punching process on the high cycle fatigue strength of the M330-35A electrical steel by Helmi Dehmani, Charles Bruggerb, Thierry Palin-Lucb, Charles Mareauc, Samuel Koechlina. 6. Analysis of Wire-EDM finishing cuts on large scale ZrO2-TiN hybrid spark plasma sintered blanks by Frederik Vogelera, Bert Lauwersa and Eleonora Ferrarisa. 7. Life estimation of knee joint prosthesis by combined effect of fatigue and wear by B.R. Rawala, Amit Yadav, Vinod Parea. 8. Fatigue life response of P355NL1 steel under uniaxial loading usingKohout-Věchet model by J.A.F.O. Correiaa, M. Calventeb, S. Blasónb, G. Lesiukc,I.M.C. Brása, A.M.P. De Jesusa, P.M.G.P. Moreiraa, A. Fernández-Cantelib. 9. Estimation of Truck Frame Fatigue Life under Service Loading by A.N. Savkina, A.S. Gorobtsova, K.A. Badikova. 10. Fatigue strength of marked steel components by Natalie Stranghöner, Dominik Jungbluth. 11. Fatigue tests and life estimation with specimens extracted from welded structures by Sohei Kanna, Yoichi Yamashita. 12. An experimental buckling study of column-supported cylinder by Olgerts Ozolins, Kaspars Kalnins. 52

13. Buckling analysis of pressure vessel based on finite element method by J Shen. 14. Numerical study on lateral – tortional buckling of honeycomb beam by Danny Gunawan. 15. Experimental test for estimation of buckling load on un stiffened cylindrical shells by vibration correlation technique by Eduards Skukis and Arbelob.

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