A Prediction Method of Galling Position in Square Cup Drawing

Abstract

A new method for predicting the position of the galling generation in square cup drawing is proposed based on the fact that galling at a drawn cup occurs at the position subjected to the maximum temperature and at the moment that the position is just sliding out from the die. Three kinds of blank shape, square, octagon, and tricontadigon are used to change the galling position on the drawn cup. FEM simulation shows that galling on the drawn cup occurs at the top of the boundary between the drawn area and the bent area for the square blank and at the top of the middle of the drawn zone for the octagon or tricontadigon blank. Demonstration experiments using a high-tensile-strength steel sheet under a lubricated condition show that the galling on the drawn cup does occur as predicted by FEM simulation. Galling on the die surface is left at the path end of the galling position of the blank material. It is also found that the sliding distance after the galling position of the blank reaches the maximum temperature gives a great effect on the galling generation: the longer the sliding distance is, the easier the galling generation becomes.