Description of an in situ method to measure the punch wear during blanking

Abstract

The purpose of this study is to develop a new method in order to measure the punch wear on a real stamping press during blanking. This in situ measuring method has been used for measuring the wear of tungsten carbide punches during blanking of thin copper alloy sheet steels (approximately 1/10 mm). As the quality of the final parts is largely influenced by the dimensions of the punch, the wear of the punch as low as a few micrometers must be avoided and consequently measured.So the difficulties to measure such a small wear amount on a high speed real industrial process (800 p/min) associated with the small overall dimensions of the punch is a great challenge.None of the existing measuring techniques (mainly geometrical) can ensure a continuous wear measurement without dismantling the blanking punch. The wear measurement technique developed for this study is the thin layer activation technique. The working area of the punch has been activated by means of a particles beam. The decay of the activity of the punch allows the punch wear to be monitored. Care has been taken to obtain a precise measurement of the punch wear during blanking.The results of the measurements of punch wear on an industrial stamping press are presented for various working conditions. For example, the influence of the punched material and the amount of lubrication upon the wear kinetics are described.