板の曲げ加工時に生ずる長手反り変形の解析--板の曲げ加工時に生ずる反り変形の解析 第2報

摘要

In the bending of long and narrow sheet metal, saddle shape camber can be seen along the ridge line direction. The camber can be divided into edge camber and longitudinal camber by the difference of generation cause. Following the previous paper about the analysis of edge camber, the longitudinal camber is analyzed theoretically in this paper. The generation mechanism is demonstrated, and a practical, simple formula is proposed, by which the characteristic of the longitudinal camber deformation is investigated. It is clarified that the camber is caused by the difference of strain ratio in elastic and plastic deformation (the ratio is "Poisson's ratio" in elastic state). The camber becomes larger with increment of Lankford's anisotropy parameter r value. Moreover the amount of camber increases proportionally to the square of sheet length, spring back angle of bending. On the other hand, it decreases proportionally to moment of inertia of the bent products. The results calculated by the proposed equations are in good agreement with the experiments.