| 摘要 |
PURPOSE:To improve the strength and the yield by setting a ratio of the outside diameter of a tubular base material and the outside diameter of a spherical hollow article, to a specified range, executing the rotational forging, and subsequently, bringing both end opening parts to a machine finish. CONSTITUTION:A ratio d/D of an outside diameter (d) of a tubular base material 3 and an outside diameter D of a hollow spherical article is set in advance to a range of 0.6-1. A punch 41 and a die 42 of a rotary forming machine 4 are inclined by an angle theta and provided, and in a state that the die 42 is made to stand still, the punch 41 is rotated around a shaft A and the shaft A is revolved around a shaft B. Thereafter, the tubular base material 3 is set to the forging machine 4 and the rotational forging is executed. Next, a necessary machine finish working is performed to opening parts 51, 52 of a hollow spherical body 5, and a hollow spherical article is completed. The base material 3 is brought to forming working for the most part by the rotational forging, therefore, the yield of a product is improved, and also the strength is improved by continuing a metallic flow.
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