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Types of press tools

Article · January 2012

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Types of press tools 1

Types of press toolsPress tools are commonly used in hydraulic, pneumatic, and mechanical presses to produce components at highvolumes. 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 also be specified as a blanking tool, piercingtool, bending tool etc.[1]

Classification of press tools

Blanking tool

Blanking Tool

•• When a component is produced with onesingle punch and die where the entire outerprofile is cut in a single stroke the tool iscalled a blanking tool.

•• Blanking is the operation of cutting flatshapes from sheet metal.

•• The outer area of metal remaining after ablanking operation is generally discarded aswaste.

• Size of blank or product is the size of the die & clearance is given on punch.•• It is a metal cutting operation.

Piercing Tool

Piercing tool

Piercing involves cutting of clean holes with aresulting scrap slug. The operation is called diecutting and can also produce flat componentswhere the die, the shaped tool, is pressed into asheet material employing a shearing action to cutholes. This method can be used to cut parts ofdifferent sizes and shapes in sheet metal, leatherand many other materials.

Cut off tool

Cutoff tool

Cut off operations are those in which a strip ofsuitable width is cut to length in a singleoperation. Cut-off tools can produce many parts.The required length of strip can be cut off forbending and forming operations using this tool.

Types of press tools 2

Parting off toolPartings are similar, in that a discrete part is cut from a sheet or strip of metal along a desired geometric path. Thedifference between a cutoff and a parting is that a cutoff can be nestled perfectly on the sheet metal, due to itsgeometry. With cutoffs, the cutting of sheet metal can be done over one path at a time and there is practically nowaste of material. With partings, the shape can not be nestled precisely. Partings involve cutting the sheet metalalong two paths simultaneously. Partings waste a certain amount of material, that can be significant.

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

Trimming Tool

Shaving tool

Shaving removes a small amount of materialaround the edges of a previously blankedstampings or piercing. A straight, smooth edge isprovided and therefore shaving is frequentlyperformed on instrument parts, watch and clockparts and the like. Shaving is accomplished inshaving tools especially designed for thepurpose.

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

Bending Tool

Forming tool

Forming tools apply more complex forms towork pieces. The line of bend is curved insteadof straight and the metal is subjected to plasticflow or deformation.

Drawing tool

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

Types of press tools 3

Drawing Tool

This type of Press tool is used to perform onlyone particular operation therefore classifiedunder stage tools.

Progressive tool

A progressive tool differs from a stage tool inthe following respect: in a progressive tool thefinal component is obtained by progressing thesheet metal or strip in more than one stage. Ateach stage the tool will progressively shape thecomponent towards its final shape, with the finalstage normally being cutting-off.

Compound toolThe compound tool differs from progressive and stage tools by the arrangement of the punch and die. It is aninverted tool where blanking and piercing takes place in a single stage and also the blanking punch will act as thepiercing die.

Combination toolIn a combination tool two or more operations such as bending and trimming will be performed simultaneously. Twoor more operations such as forming, drawing, extruding, embossing may be combined on the component withvarious cutting operations like blanking, piercing, broaching and cut off takes place- it can perform a cutting and noncutting operations in a single tool.

General Press tool ConstructionThe general press tool construction will have following elements:•• Shank: It is used to locate the press tool in press for alignment purpose.•• Top Plate: It is used to hold top half of the press tool with press slide.•• Punch Back Plate : This plate prevents the hardened punches penetrating into top plate.•• Punch Holder: This plate is used to accommodate the punches of press tool.•• Punches : To perform cutting and not cutting operations either plain or profiled punches are used.•• Die Plate: Die plate will have similar profile of the component where cutting dies usually have holes with land

and angular clearance and non cutting dies will have profiles.•• Die Back Plate:This plate prevents the hardened Die inserts penetrating into bottom plate.• Guide Pillar & Guide Bush : Used for alignment between top and bottom halves of the press tools.•• Bottom plate:It is used to hold bottom half of the press tool with press slide.•• Stripper plate: it is used to strip off the component from punches.•• strip guides: It is used to guide the strip into the press tool to perform the operation.

Types of press tools 4

Press tool

Cutting force in Press tool

In general cutting force (CF) can be calculatedusing formula: CF =L x S x ζmaxcutting force will be in Newton(N) Where, L =Cut length in mm,(perimeter of profile to be cut)Ex: 40 mm square to be cut will have cut lengthof 160 mmS = Sheet metal thickness in mm,ζmax = Maximum shear strength of sheet metalMPa

Stripping Force

Stripping force will be usually 10 to 20 % ofcutting force.

Press ForcePress force will be cutting force with stripping force Press Force = Cutting force + Stripping force

Fits in Press Tools•• Punch holder and Punches =H7/k6•• Punch and Stripper = H7/g6•• Guide Pillar and Guide bush = H7/g6•• Guide bush and Top plate = H7/p6•• Guide pillar and bottom plate = H7/p6•• Dowel and plate = H7/m6

References[1] Cyril Donaldson, George H LeCain, V C Goold, Tool design 3rd edition, Tata McGraw-Hill Education, New Delhi.

Article Sources and Contributors 5

Article Sources and ContributorsTypes of press tools  Source: http://en.wikipedia.org/w/index.php?oldid=622315518  Contributors: 220 of Borg, Alan Liefting, Altaïr, AsceticRose, Biscuittin, DoctorKubla, Ekabhishek,Gravuritas, HMSSolent, JaconaFrere, Jim1138, Katharineamy, KylieTastic, Magioladitis, Mild Bill Hiccup, Penfold20, Pinethicket, PrabhakarPurushothaman, Rasika251, Rich Farmbrough,SchreiberBike, Vieque, 37 anonymous edits

Image Sources, Licenses and ContributorsFile:Blanking Tool.png  Source: http://en.wikipedia.org/w/index.php?title=File:Blanking_Tool.png  License: Creative Commons Zero  Contributors: PrabhakarPurushothaman, Sfan00 IMGFile:Piercing tool.png  Source: http://en.wikipedia.org/w/index.php?title=File:Piercing_tool.png  License: Creative Commons Zero  Contributors: PrabhakarPurushothaman, Sfan00 IMGFile:Cutoff tool.png  Source: http://en.wikipedia.org/w/index.php?title=File:Cutoff_tool.png  License: Creative Commons Zero  Contributors: PrabhakarPurushothaman, Sfan00 IMGFile:Trimming Tool.png  Source: http://en.wikipedia.org/w/index.php?title=File:Trimming_Tool.png  License: Creative Commons Zero  Contributors: PrabhakarPurushothaman, Sfan00 IMGFile:Bending_tool.png  Source: http://en.wikipedia.org/w/index.php?title=File:Bending_tool.png  License: Creative Commons Zero  Contributors: PrabhakarPurushothaman, Sfan00 IMGFile:Drawing_tool.png  Source: http://en.wikipedia.org/w/index.php?title=File:Drawing_tool.png  License: Creative Commons Zero  Contributors: PrabhakarPurushothaman, Sfan00 IMGFile:Press_tool.png  Source: http://en.wikipedia.org/w/index.php?title=File:Press_tool.png  License: Creative Commons Zero  Contributors: PrabhakarPurushothaman, Sfan00 IMG

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