| 摘要 |
PURPOSE:To improve the yield of the rough shape having the necessary shape by cutting a pipe in the necessary dimension, heating the end part and fitting it to a die for forming and press-fitting a punch performing an upsetting and pipe expansion simultaneously into a heating end part. CONSTITUTION:The end part of a pipe material 56 cut in the necessary size is heated by high frequency induction heating or adequate heating furnace and fitted into a die 58. On the other hand a punch 60 is fitted to a head or ram and press-fitted into the heated end part of a pipe 56. The punch 60 is equipped with a papillate or conical pipe expansion part 60a and the shoulder part 60b plastically deforming the pipe material 56 by pressing it in the axial line direction by abutting to the pipe end part. On the die 58 the papillate or conical recessed part 58a in the shape corresponding to the pipe expansion part 60a of the punch 60 is provided. A papillate or conical diameter expansion part 56a is formed at the heating end part of the pipe material 56 with the cooperation of the die 58 and punch 60.
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