Drawing of stainless shaped steel microwire of 400-600 mu m size

摘要

In the round-to-square and round-to-hexagon drawing for the formation of microwires, the effect of drawing conditions on the dimensional accuracy of the wires was evaluated. The following was found: It was possible to obtain shaped square microwires with a 400 mu m diameter and hexagonal microwires with a 600 mu m diameter. From experimental and FEM analysis results, the optimum drawing conditions required to obtain shaped microwires with good dimensional accuracy were determined. The optimum conditions include increasing the reduction RIP compared to the case of round-to-round drawing and increasing the die half angle slightly. There exists a die half angle which exhibits a minimum drawing stress in the shaped drawing using round mother wires, and this die half angle was determined. Regarding the residual stress distribution of the shaped drawn microwires, it was found by FEM analysis that tensile stress was generated at the surface and compressive stress was generated at the center of the wire, similar to the case of round-to-round drawing. To decrease the surface tensile stress, the die half angle should be decreased and reduction should be increased. Based on the above discussions, the optimum drawing conditions for the shaped microwires are: R/P =25 approx 35 percent and die half angle alpha= 12 deg approx 18 deg.