PURPOSE: To bend shapes by extruding through in high shape precision while error element due to spring back is suppressed.
CONSTITUTION: When a moving die is arranged at the displaced position relative to a fixed die and shapes is bent through the fixed die and moving die, a correcting coefficient C represented with the ratio Ma/Mt of an actual operating quantity Ma to theoretical operating quantity Mt of moving die is calculated by the next equation, an operating quantity of the moving die is determined based on the correction coefficient calculated. C=(A×(Z×σ0.2)+0.3)×10-3×R+B, wherein, A: coefficient in a range of (8-11)×10-6, B: constant in a range of 3.0-3.6, Z: average value (mm3) of section modulus of tension side and compression side at shape cross section, σ0.2: 0.2 proof stress (kgf/mm2) in tensile test, R: curvature radius (mm), by this method, working condition is easily set without repeating trial and error.
HAKAMATA TADASHI
HINO HARUMICHI
SUGIYAMA KEIICHI
