Fast cutting clearance evaluation in piercing processes by means of vision system

Abstract

Cutting is one of the most commonly used processes in sheet metal forming. One of the most important parameters of this process is the clearance. Clearance value is defined as the distance between the cutting edge of the punch and the cutting edge of the die. It is relative to the sheet thickness and has a significant effect on the quality of the cutting hole surface, the size of the hole and the possibility of a burr occurring or the rollover area on the edge of the product. In the cutting process clearance value increase during tools wear. Its correct evaluation allows to determine moment when the tools should be replaced. In the presented paper authors have proposed fast clearance evaluation method base on the geometry measurement of the finished product. Measurements was carried out by means of vision system equipped with specially designed illumination, which allows to extract the rollover area at the edge of the hole. Then measured rollover area diameter was compared to clearance values.