design and analysis progressive tool designijrpublisher.com/gallery/67-december-2018.pdf · design...

DESIGN AND ANALYSIS PROGRESSIVE TOOL DESIGN

#1SETTI NOOKARAJU, PG STUDENT

#2MRS.VENKATA LAKSHMI, ASSISTANT PROFESSOR

DEPARTMENT OF MECHANICAL ENGINEERING

KAKINADA INSTITUTE OF ENGINEEING AND TECHNOLOGY, KAKINADA

ABSTRACT Sheet metal is simply metal formed into thin

and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material. Thicknesses can vary significantly, although extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate. Design of sheet metal dies is a large division of tool engineering, used in varying degree in manufacturing industries like automobile, electronic, house hold wares and in furniture.

In our project we have learnt about different sheet metal dies, sheet metal operations and studied the design of progressive press tool.

I. INTRODUCTION TO

SHEETMETAL

Introduction

Sheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material. Thicknesses can vary significantly, although extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate. Sheet metal processing

The raw material for sheet metal manufacturing processes is the output of the rolling process. Typically, sheets of metal are sold as flat, rectangular sheets of standard size. If the sheets are thin and very long, they may be in the form of rolls. Therefore the first step in any sheet metal process is to cut the correct shape and sized ‘blank’ from larger sheet.

Fig.1.Shearing Operations: Punching, Blanking and Perforating

Fig.2.Common Die-Bending Operations Various Bending Operations

Fig.3.Schematic illustration of a stretch-forming process.

Fig.4. Schematic of the Drawing process.

International Journal of Research

Volume 7, Issue XII, December/2018

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Fig.5. Eight-roll sequence for the roll forming of a box channel

Finishing processes

Material properties, geometry of the starting material, and the geometry of the desired final product play important roles in determining the best process.

Equipments

Basic sheet forming operations involve a press, punch, or ram and a set of dies Presses

Mechanical Press - The ram is actuated using a flywheel. Stroke motion is not uniform. Ref fig.6

Hydraulic Press - Longer strokes than mechanical presses, and develop full force throughout the stroke. Stroke motion is of uniform speed, especially adapted to deep drawing operations. Ref fig.7

Fig.6 Mechanical Press

Fig.7 Hydraulic Press

Dies and Punches

Simple- single operation with a single stroke

Compound- two operations with a single stroke

Combination- two operations at two stations

Progressive- two or more operations at two or more stations with each press stroke, creates what is called a strip development

Fig 8 Progressive dies Punches

Tools and Accessories The various operations such as cutting,

shearing, bending, folding etc. are performed by these tools. Marking and measuring tools

Steel Rule - It is used to set out dimensions.

Try Square - Try square is used for making and testing angles of 90degree

Scriber – It used to scribe or mark lines on metal work pieces. Divider - This is used for marking

circles, arcs, laying out perpendicular lines, bisecting lines, etc

Marking and measuring tools Cutting Tools

Straight snip - They have straight jaws and used for straight line cutting. Ref fig.10

Curved snip - They have curvedblades for making circular cuts. Ref fig.10a



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fig.9.Straight snip

Fig.10. Curved Snip

Striking Tools Mallet - It is wooden-headed hammer of round or rectangular cross section. The striking face is made flat to the work. A mallet is used to give light blows to the Sheet metal in bending and finishing. Ref fig.11

Fig.11 Types of Mallets

II. MATERIALS

Stainless steel

The three most common stainless steel grades available in sheet metal are 304, 316, and 410.

Grade 304 is the most common of the three grades. It offers good corrosion resistance while maintaining formability and weldability. Available finishes are #2B, #3, and #4. Note that grade 303 is not available in sheet form.

Grade 316 offers more corrosion resistance and strength at elevated temperatures than 304. It is commonly used for pumps, valves, chemical equipment, and marine applications. Available finishes are #2B, #3, and #4.

Grade 410 is a heat treatable stainless steel, but does not offer as good corrosion resistance. It is commonly used in cutlery. The only available finish is dull.

Aluminium

The four most common aluminium grades available as sheet metal are 1100-H14, 3003-H14, 5052-H32, and 6061-T6.

Grade 1100-H14 is commercially pure aluminium, so it is highly chemical and weather resistant. It is ductile enough for deep drawing and weldable, but low strength. It is commonly used in chemical processing equipment, light reflectors, and jewelry.

Grade 3003-H14 is stronger than 1100, while maintaining the same formability and low cost. It is corrosion resistant and weldable. It is often used in stampings, spun and drawn parts, mail boxes, cabinets, tanks, and fan blades.

Grade 5052-H32 is much stronger than 3003 while still maintaining good formability. It maintains high corrosion resistance and weldability. Common applications include electronic chassis, tanks, and pressure vessels.

Grade 6061-T6 is a common heat-treated structural aluminium alloy. It is weldable, corrosion resistant, and stronger than 5052, but not as formable. Note that it loses some of its strength when welded. It is used in modern aircraft structures, generally replacing the older 2024-T4 alloy.

GAUGE

The sheet metal gauge (sometimes spelled gage) indicates the standard thickness of sheet metal for a specific material. For most materials, as the gauge number increases, the material thickness decreases.

Sheet metal thickness gauges for steel are based on the weight of steel, allowing more efficient calculation of the cost of material used. The weight of steel per square foot per inch of thickness is 41.82lb (18.96kg), this is known as the Manufacturers' Standard Gage for Sheet Steel. For



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other materials, such as aluminium and brass, the thicknesses will be different.

III. DESIGN OF SHEET METAL DIES INTRODUCTION

Design of sheet metal dies is a large division

of tool engineering, used in varying degree in manufacturing industries like automobile, electronic, house hold wares and in furniture.

There is no doubt that accuracy achieved by the new ideas in design and construction applied by the press tool designer, coupled latest development made in related fields made more productive, durable and economical.

These are

The variety in press specification gives the liberty to the designer to think innovative.

The Safety Provisions has reduced the accidents and the productivity has been increased.

“Simulation Software’s” give the designer freedom from taking risky decisions.

The use and availability of Standard Elements has reduced the design and development period

The concept of “Flexible Blank Holder” has given the scope to control the flow of the material in a better way.

Hardened and toughened new martial & heat treatment process made the design easy.

The latest machining process made the complex designs made easy, like wire cut, EDM, Profile Grinding.

Four factors are essential contributions to first class presswork are

Good operation planning Excellent tool design Accurate tool design Knowledge press setting

Design of any Press Tool involves the following Steps

1. Determination of force (Press Tonnage) required for the operation 2. Selection of Press for requisite force, work piece size and shape 3. Determination of shut height of the tool 4. Computing die thickness, and margins (minimum cross-section) 4. Drawing Strip Layouts and comparing Material utilization 6. Design of locating Elements 7. Selection of Locating Elements 8. Selection of Hardware 9. Drawing die plan and selection of pillar die set

10. Deciding punch length and mounting 11. Finding Centre of Pressure and Checking scrap Disposal 12. Drawing Details

TYPES OF PRESS TOOLS

Press tools are commonly used in hydraulic and mechanical presses to produce components at a high productivity rate. Generally press tools are categorized by the types of operation performed using the tool, such as blanking, piercing, bending, forming, forging, trimming etc. The press tool will



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also be speciopified as blanking tool, piercing tool, bending tool etc.

CLASSIFICATION OF PRESS TOOLS

Press tools are classified into:

STAGE TOOLS

Blanking tool

When a component is produced with one single punch and die were the entire profile is cut in single stoke is called Blanking tool.

Piercing Tool

Piercing involves cutting of clean holes with resulting scrape slug. The operation is often called piercing, In general the term piercing is used to describe die cut holes regardless of size and shape. Piecing is performed in a press with the die. the piercing tool is used to pierce the holes as secondary tool such as after bending of component etc.

Cut off tool

Cut off operations are those in which strip of suitable width is cut to lengthen single. cut-off tools can produce many parts. The required length of strip can be cut off for bending and forming operation using this tool.

Parting off tool

Parting off is an operation involve two cut off operations to produce blank from the strip. During parting some scrape is produced. Therefore parting is the next best method for cutting blanks. It is used when blanks will not rest perfectly. It is similar to cut off operation except the cut is in double line. This is done for components with two straight surfaces and two profile surfaces

Trimming tool

When cups and shells are drawn from flat sheet metal the edge is left wavy and irregular, due to uneven flow of metal. This irregular edge is trimmed in a trimming die. Shown is flanged shell, as well as the trimmed ring removed from around the edge. While a small amount of Material is removed from the side of a component in trimming tool.

Shaving tool

Shaving removes a small amount of material around the edges of a previously blanked stampings or piercing. A straight, smooth edge is provided and therefore shaving is frequently performed on instrument parts, watch and clock parts and the like. Shaving is accomplished in shaving tools especially designed for the purpose.

Bending tool

Bending tools apply simple bends to stampings. A simple bend is done in which the line of bend is straight. One or more bends may be involved, and bending tools are a large important class of pres tools.

Forming tool

Forming tools apply more complex forms to work pieces. The line of bend is curved instead of straight and the metal is subjected to plastic flow or deformation.

Drawing tool

Drawing tools transform flat sheets of metal into cups, shells or other drawn shapes by subjecting the material to severe plastic deformation. Shown in fig is a rather deep shell that has been drawn from a flat sheet.

This type of Press tools are used to perform only one particular operation.

Progressive tool

Progressive tool differs from the stage tool by the following aspect, In progressive tool the final component is obtained by progressing the sheet metal or strip in many stages. In each and every stages the component will get its shape stage by stage the full shape will be obtained at the final stage.

Compound tool

The compound tool differs from progressive and stage tool by the arrangement of punch and die. It is a inverted tool were blanking and piercing takes place in a single stage and also blanking punch will act as piercing die.



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Combination tool

In combination tool two or more operations will be performed simultaneously such as bending and trimming takes place in a single stage. In combination tool two or more operations such as forming, drawing, extruding, embossing may be combined on the component with various cutting operations like blanking, piercing, broaching and cut off takes place.

PROGRESSIVE TOOL DESIGN

A die containing a series of stations that perform one press operation after another in series. A progressive die gradually forms a part as it moves through the die, and the last operation separates the part.

Progressive dies provide an effective way to convert raw coil stock into a finished product with minimal handling. As material feeds from station to station in the die, it progressively works into a completed part.

Progressive dies usually run from right to left. The part material feeds one progression for each press cycle. Early stations typically perforate holes that serve as pilots to locate the stock strip in later stations.

There are many variations of progressive die designs. The design shown here illustrates some common operations and terminology associated with progressive dies.

Progressive stamping is a metalworking method that can encompass punching, coining, bending and several other ways of modifying metal raw material, combined with an automatic feeding system.

The feeding system pushes a strip of metal (as it unrolls from a coil) through all of the stations of a progressive stamping die. Each station performs one or more operations until a finished part is made. The final station is a cutoff operation, which separates the finished part from the carrying web. The carrying web, along with metal that is punched away in previous operations, is treated as scrap metal.

The progressive stamping die is placed into a reciprocating stamping press. As the press moves up, the top die moves with it, which allows the material to feed. When the press moves down, the die closes and performs the stamping operation. With each stroke of the press, a completed part is removed from the die.

Since additional work is done in each "station" of the die, it is important that the strip be advanced very precisely so that it aligns within a few thousandths of an inch as it moves from station to station. Bullet shaped or conical "pilots" enter previously pierced round holes in the strip to assure this alignment since the feeding mechanism usually cannot provide the necessary precision in feed length.

Progressive stamping can also be produced on transfer presses. These are presses that transfer the components from one station to the next with the use of mechanical "fingers". For mass productions of stamped part which do require complicated in press operations, it is always advisable to use a progressive press. One of the advantages of this type of press is the production cycle time. Depending upon the part, productions can easily run well over 800 parts/minute. One of the disadvantages of this type of press is that it is not suitable for high precision deep drawing which is when the depth of the stamping exceeds the diameter of the part. When necessary, this process is performed upon a transfer press, which run at slower speeds, and rely on the mechanical fingers to hold the component in place during the entire forming cycle. In the case of the progressive press, only part of the forming cycle can be guided by spring loaded sleeves or similar, which result in concentricity and ovality issues and non uniform material thickness. Other disadvantages of progressive presses compared to transfer presses are: increased raw material input required to transfer parts, tools are much more expensive because they are made in blocks (see fig. 1) with very little independent regulation per station; impossibility to perform processes in the press that require the part leave the strip (example beading, necking, flange curling, thread rolling, rotary stamping ect).



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The dies are usually made of tool steel to withstand the high shock loading involved, retain the necessary sharp cutting edge, and resist the abrasive forces involved.

The cost is determined by the number of features, which determine what tooling will need to be used. It is advised to keep the features as simple as possible to keep the cost of tooling to a minimum. Features that are close together produce a problem because it may not provide enough clearance for the punch, which could result in another station. It can also be problematic to have narrow cuts and protrusions.

Applications

An excellent example of the product of a progressive die is the lid of a beverage can. The pull tab is made in one progressive stamping process and the lid & assembly is made in another, the pull tab simultaneously feeding at a right angle into the lid & assembly process.

DESIGNING PROGRESSIVE DIES

The decision to produce a part progressively is usually determined by two factors: the volume of production and the complexity of the part. These two factors are instrumental in the design and construction of the tooling. It is important to address all factors that will contribute to the desired level of part quality, tool maintenance, and tooling life. Trade-offs will be necessary to reach most decisions, and all will affect tooling costs.

PART ORIENTATION

The process begins with determining how the part will be run through the die. This is governed by the features of the part and the locations of the datums and critical tolerances. Then, the trade-offs begin.

Optimizing material usage may require rotating the part in the strip, which changes the grain direction of the steel in the part and thus can affect the strength of any forms in the part. Forming with the grain can cause cracking and fatiguing of the metal and make holding consistent form angles more difficult. Therefore, the form will be far more susceptible to problems associated with the chemical makeup of each coil that is run.

For example, Figure 1shows a part for the computer industry that was rotated in the strip to guard against inconsistent form angles that could be caused by

differences between coils. The part contained critical dimensions with 0.025-millimeter tolerances dependent on the forms. Rotating the strip to ensure more consistent forms was not the most efficient use of material. In this case, however, part tolerances won out over optimizing material usage.

Figure 12: This part was rotated in the strip to maintain critical tolerances better.

Part configuration could provide a second motivation for rotating a part in the strip. If cam forming or piercing is required to make the part progressively, rotating the part may be the best, and sometimes only, option because the cam and driver can take up a significant amount of room. The part typically is rotated so that the cams' functions are perpendicular to the coil. This provides the easiest and most accessible condition for the cams.

One such compromise is shown in Figure 2. The part is carried through with a ladder-style carrier, which adds material to the coil width because only two small areas are available for carrying the part. Also, because of the shape and length of the forms, a significant amount of lift is needed. External stock lifters carrying the ladder strip work well in high-lift situations.



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Figure 13: Compromises among excessive lift, material use, and tooling cost and complexity were necessary to form this part.

One final consideration for part orientation within the strip is that a part should be rotated so that the feed is as short as possible. This is especially true for heavier materials and narrow coils. The slitting process can cause camber in coils that can make feeding difficult. A shorter progression feed runs faster and has less chance to cause feed problems. When a substantial difference between the length and width of the part exists, it is usually more cost-effective to build the tooling with the shorter lead.

CARRYING THE PART

How parts are carried in the strip affects how well the die feeds, the ability to lift the strip for feeding, and the ability to produce consistent-quality parts.

Three basic options are available for carrying a part, although many variations of each also can be used. In the most straightforward approach, parts are carried by the scrap between them. Excess material equal to one to two material thicknesses per side is required for trimming. This method typically produces minimal scrap.

Certain part configurations are needed to use this method. When rotated and laid out end to end, the parts must have enough usable area on both the leading and trailing edges of the progression (see Figure 3).

Figure 14: One side of the strip is used to carry this part through a progressive die.

The second basic strip option, in which a part is carried on one side of the strip, is shown in Figure 4. This style is suitable for parts that require a great deal of forming on as many as three sides. It also

improves accessibility if cam piercing or forming is required.

Figure 15: The parts shown here are carried by the scrap between them, which also serves as stretch webs for the center draw.

Lifting the strip through the die can become more difficult when this carrier option is used. A stock lifter on the edge of the strip is not sufficient—lifters are needed in the center of the strip for balancing, or feeding the strip through the die can become a problem. If large or numerous flanges are to be formed down, achieving the proper lift can be difficult.

This type of carrier can cause another feeding problem. Trimming a large quantity of material from one side of the coil can cause camber in the strip as stresses are released from the steel. The more progressions in a die, the greater is the risk of feed and pilot alignment problems caused by camber.

Part configuration, stock material thickness, and how narrow the carrier must be are all factors that influence whether camber becomes a problem. To prevent camber, the coil width should be increased so that the carrier side of the coil also can be trimmed. The additional trim releases stresses from the opposite side of the coil and balances the strip. Even with the additional trim, carrying the part on one side of the strip can be the most effective method to run a part from a material usage standpoint.

The third carrier option is the ladder style. Some of the advantages of the ladder carrier were discussed earlier. These carriers work well with complex parts and with those requiring significant amounts of lift.



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Because this method allows a strip to feed easily, it also is often used in applications in which higher feed rates are needed.

The ladder carrier uses more material per part. Often, however, a part cannot be produced progressively any other way. If production volumes are borderline to begin with in terms of justifying progressive tooling, the added costs of the more complex progressive die and additional material waste may make producing the part through multiple operations a better option.

IV. STATIC ANALYSIS OF PISTON STEEL material TRANSFER PUNCH Save PRO E model as .iges format →→Ansys → Workbench→ Select analysis system → study SATIC structural → double click →→Select geometry → right click → import geometry → select browse →open part → ok →select mesh on work bench → right click →edit

Double click on geometry → select MSBR → edit material → Density 7810 kg/m³ Young's modulus 200000 MPa Passion ratio 0.33 Select mesh on left side part tree → right click → generate mesh → Meshed model

Select static structural right click → insert → select displacement area > pressure area also Select solution right click → solve → ok Solution right click → insert → deformation → total → Solution right click → insert → strain →

equivalent (von-misses) → Solution right click → insert → stress → equitant (von-mises) →Right click on deformation → evaluate all result Total Deformation

STRESS

STARIN

H13 STEEL Total Deformation



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STRESS

STARIN

STATIC ANALYSIS OF PISTON STEEL material PIN PUNCH STARIN


STRESS

STARIN

STATIC ANALYSIS OF PISTON STEEL material ROLL PUNCH Save PRO E model as .iges format →→Ansys → Workbench→ Select analysis system → study SATIC structural → double click →→Select geometry → right click → import geometry → select browse →open part → ok →select mesh on work bench → right click →edit

Double click on geometry → select MSBR → edit material → Density 7810 kg/m³ Young's modulus 200000 MPa Passion ratio 0.33 Select mesh on left side part tree → right click → generate mesh →



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Meshed model

Select static structural right click → insert → select displacement area > pressure area also Select solution right click → solve → ok Solution right click → insert → deformation → total → Solution right click → insert → strain → equivalent (von-misses) → Solution right click → insert → stress → equitant (von-mises) →Right click on deformation → evaluate all result Total Deformation

STRESS

STARIN


STRESS

STARIN

V. CONCLUSION Sheet metal is simply metal formed into thin

and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material. Thicknesses can vary significantly, although extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate. Design of sheet metal dies is a large division of tool engineering, used in varying degree in manufacturing industries like automobile, electronic, house hold wares and in furniture.In our project we have learnt about different sheet metal dies, sheet metal operations and studied the design of progressive press tool.



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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 Vol. 130–131, pp. 2–8, 2002.

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, Vol. 153–154, pp. 1005–1010, 2004.

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, Vol. 110, Issue 1, pp. 36–46, 2001.

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, Vol. 36, Issue 3, pp. 367-378, 1996.

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, Vol. 130–131, pp. 626–631, 2002.



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