Study on contact compress stress variation rule on fineblanking blank holder

A new film sensor using PVDF film as sensing element was developed to measure the contact stress,which overcame two weaknesses as follows:when calculating blank holder force by hydraulic pressure,the accuracy of transmission link was reduced;when researching the blank holder force,the difference of contact stresses caused by different contact areas were ignored.The fineblanking process of H62 sheet with thickness of 0.65 mm was testet by the developed stress sensor.The results show that the existing of contact stress is performed in the two waves with exponential decay after the peak,the contact stress rises as the result of the increase in metal flow resistance caused by the V-shaped tooth being pressed into sheet.