Article Preview
Top1. Introduction
The square cups of sheet metals are widely used in many industrial fields. Commonly, the square cups are manufactured by deep drawing using flat blanks of sheet metal. The traditional design of drawing dies are complicated and tedious procedure, in spite of all precautionary measures there are several chances of denting, cracking and wrinkling which needs to be rectified. Using these techniques leads to high rates of scrap from sheet metal drawing processes. Therefore, it is very important to replace these techniques by a computer aided method to determine the strain distributions, tool forces and potential sources of defects and failures. One of the most popular methods in simulating and optimizing the sheet metal forming today is the finite element (FE) simulation (Yoon, 2014). FE simulation allows to capture behaviour that cannot be readily measured it provides deeper insight into the sheet metal forming. Nowadays, FE simulation is highly adopted in by modern industry to reduced production cost and time prototyping, improved formability and easy modification of part design. In deep drawing processes FE simulation have been applied to understand the deformation mechanism, improve the quality of deep drawn parts, facilitate the metal flow into die cavity, maximizing the height of drawn cup, and shorten design cycle (Regueras, 2014); (Li et al, 2006).
The deep drawability and quality of deep drawn products depend upon many process parameters such as; blank thickness, blank and die geometries, holding pressure, blank materials, friction conditions at tools/blank interface surfaces, and so on. Many researchers have been carried out using diverse technologies in order to better understand square cup drawing processes. The work of (Marumo et al, 1999,1998);(Kuwabara et al, 1993); and (Kawai,1987) investigated the effects of drawing process parameters on the deep drawability of square cups made of aluminum sheets, while (Chen & Lin, 2007) investigated the effects of deep drawing parameters on the deformation characteristics for the forming square cups of stainless steel. (Kitayama et al, 2010) introduced an algorithm to determine the trajectory of the blank holder force in square cup drawing process. (Modi & Kumar, 2013) developed a method to determine the path of the variable blank holder force for successful hydroforming of the cups with the assistance of programmable logic controller and data acquisition system. The main aspect to be considered in drawing of square cup is that deformation states vary along the contour of the cup cross section which leads to metal flow concentration at the square cup corners (Saxena & Dixit, 2009).