Chipping damage of die for trimming advanced high-strength steel sheet: Evaluation and analysis

摘要

The tool life becomes one of the critical manufacturing issues in the metal forming process of advanced high-strength steel as the material strength continually increasing. In this paper, an evaluation method on trim die chipping damage was developed. This method is based on the measurement of chipped volume, which is achieved from the area measurement on two chipped die surfaces on front and top views, to construct a missing metal triangle, which is further integrated along the die cutting edge line to obtain the loss metal volume. 18 dies made of three different materials (Caldie, AISI D2, and Vanadis 4) and six trim uphill angles were received and measured with the known total trimming cycles (hits). The measurement was achieved with two methods using two combinations of camera view directions. The die materials and trim uphill angle effect on the die performance (chipping resistance) were obtained based on average chipping rate, defined as the loss metal volume per hit. For AISI D2 dies, wide scattering of the chipping rates was seen. And it was identified that the unfavorable carbide/grain orientation relative to the trim die cutting edge line is responsible to the obtained unusual low cycle to failure. Furthermore, a simple in-line real-time die damage monitoring and measurement system is proposed, and the favorable die machining orientation relative to the rolling coordinate is suggested.