Determination of Blank Size for Non Axisymmetric and Non Standard Deep Drawn Cups

Abstract

Deep Drawing is the process of converting a flat blank into cup shaped articles like automobile panels kitchen sinks, fountain pen caps and shell cases etc. During this process a punch forces the blank to take the shape of the die cavity. If the height of the drawn cup exceeds half its diameter then the process can be termed as deep drawing. One of the primary requirements in drawing operation is estimation of blank area or blank size. It is considered to be critical because even a small variation in estimation can lead to unnecessary wastage of material. If the blank area is underestimated it leads to partially drawn cup due to insufficient material. On the other hand if the blank area is over estimated it leads to wastage in material as the excess material has to be removed by performing trimming operation. Although estimation of blank diameter is done using mathematical formulae these are based on thumb rules which are in turn based on experience. Further for nonstandard and nonaxisymmetric cups there are hardly any readymade formulae available. Hence in this work an effort is made to estimate the blank size required to form nonstandard and nonaxisymmetric cups produced by deep drawing process, both analytically and by using solid works software.