| 摘要 |
PURPOSE:To obtain a holed part having a shaft part such as a joint member or the like at a good material yield by forming a preliminary recess in the bulging part of a shaft-shaped blank material, forming the shape approximate to an intended shape then forming two recesses facing each other by indentation. CONSTITUTION:A blank material 13 having a bulging part 13a is formed by forging from a round bar blank material. The preliminary recess 14d for the 1st recess is formed to the part 13a to form a preform 14a. The bottom part 14a of the recess 14d is upset to expand the outside size A of the head part to C in succession to said forming so that the intermediate part 15e between the head part and the shaft part is made into the shape approximate to the intended finish forged shape. The 2nd recess 16f is formed by indentation to the bottom wall part 15a of such intermediate part 15. The formed article having high accuracy and high strength is obtd. by the above-mentioned method. |
