Effect of Punch Shape on Multiprocess Tube Flaring for Eccentric Parts

Abstract

In this work, by focusing on multiprocess tube flaring for eccentric parts, we studied the effect of punch shape on deformation behavior by FEM analysis. In the case of using only the eccentric punch, thickness deviation occurs in the circumferential direction and thickness reduction is enhanced because the tube is greatly flared at the circumferential position of 180 degrees. However, it is found that the thickness deviation and thickness reduction are improved by evenly flaring both sides using a concentric punch. Furthermore, although the punch shoulder radius has a negligible effect on formability, it is confirmed that the deformation near the tube edge transitions from uniaxial tension to pure shear as the punch semiangle is increased. The above result clarify that by using concentric punches with punch semiangle larger than the taper angle of the parts shape from the initial process, the thickness reduction is drastically minimized compared with other forming methods.