MANUFACTURING METHOD OF METAL BAR TO BE BENT

摘要

PROBLEM TO BE SOLVED: To improve the yield of non-defective articles by enabling the bending without causing small cracks, of a metal bar such as a cast tube and a hot extruded tube in the surface of which small cracks tend to generate when it is bent. SOLUTION: In manufacturing a bent bar by allowing a metal bar to be subjected to the continuously moving type hot bending, the heat treatment for eliminating work hardening of a surface layer part on a bar stock before the bending, is applied, and then the heat-treated bar is subjected to the hot bending.