| 摘要 |
PROBLEM TO BE SOLVED: To provide a die capable of working well without having contact between a material and the die for a shaft part in two stage reduction forging and to provide a forging method by the die which conducts good two stage reduction without generating jamming. SOLUTION: In two stage reduction, when working with a punch stroke specified by S<1.2.D0+H1, the die, which satisfies the formula of 271R1+281R2+221θ1+1000θ2-30837<0 wherein a cross sectional area reduction R1(%) of a first tapered part and a die half angleθ1 (deg) of the die, a cross sectional area reduction R2(%) of a second tapered part and a die half angleθ2 (deg) of the die, is excellent in two stage reduction.
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