Abstract:-Punching tool is used to cut and create blanks in  a sheet metal with a certain pitch。 The present day punching machine consists of a punching tool with constant pitch。 The idea of this paper is to design variable punching tool with pitch varying from min to max pitch (40-180mm) using die with guidelines。 The above design solves the problem of installing new tool for different pitches。 Due to the variable punching tool the productivity of the company increases drastically and the setup time for the different punching tool to the machine also decreases。 The initial cost of installation decreases to a maximum extent。72602

Keywords:  compound/combination  die  ;Progressive  die ;punch

;die setdie- shoe ;guide plate; shank holder; punch holder ;guide rails;  stripper  pilot;  guidepost/bush；screw; knock-out；dowel

;backing plateblank holder

I。 INTRODUCTION

Punch die which is used for cutting pieces in different methods have abundant persity in the cases of shape, dimension and type of them, hence their designing necessitate so much time mean while their cost is very much and on the other hand various design of dies more often are used only for one time, thereby these dies will be useless for other cases therefore because of these, warehousing them vastly get increases whereas the occupied space of the warehouses turns to the big problem for manufactures which it needs so much money therefore it seems necessary to use a method to design dies consist of a few parts that  be useable in different dies or in the other word, propose a method to make uniformity between common parts of dies。

Types of dies:

• Progressive dies: Parts produced with multiple operations such as, punching, blanking and notching are made at high production rates in progressive dies

• Compound Dies: Several operations on the same strip performed in one stroke at one station with a compound die。

• Transfer Dies: Sheet metal undergoes different operations at different stations in a straight line or circular path。

Die common parts:

Common part in punch metal dies consist  of  many members such top and bottom bolster, guide pillar, guide bush and shank, nevertheless there are some various cases that these are the same in some characteristics such as material, type and dimensions。 Effective parameters on proper material selection for the die common part are as follow:

Manuscript received May, 2013。

Venkatareddy Chilakala, Department Of Mechanical Engineering, K。L。University, Guntur, Andhra Pradesh, India。

Polisetti Lakshmi Manikanta, Department Of Mechanical Engineering, K。L。University, Guntur, Andhra Pradesh, India。

Samuel Eda, Department Of Mechanical Engineering, K。L。University, Guntur, Andhra Pradesh, India。

Medikonda Girija Prasad, Department Of Mechanical Engineering, K。L。University, Guntur, Andhra Pradesh, India。

- price and preparing possibility

- Mechanical specification

- Thermal operation ability

- Production capacity

In designing die common parts, some specifications of members, dies and presses are used as the  fundamental input data for their calculations。 This information in each member is as follows:

II。 BOLSTER:

A punch tool consists of two bolsters which all parts of die set up on it。 Required mechanical  specifications  for this part are high hardness and durability, moreover it must be absorb the vibration and easily machining。  Thereby  cast iron bolsters are more common than steel or aluminium bolsters。 However for manufacturing big pieces which need high rigidity and must be  stronger  under  impact loads, mostly steel bolster are used in this cases。 Required information for design and selection of bolster with considering type and dimensions of them are some parameters such as press table dimensions, die work area, shape of piece, press capacity and method of feeding plate into the die space。