| 摘要 |
PROBLEM TO BE SOLVED: To provide a working method by which tubular parts having a bulged part in the middle part are worked at a low working cost, at short cycle time, by easily maintained equipment and, even when a material to be worked is such an article as liquid leaks, without taking it into consideration. SOLUTION: In a tubular article 4 formed by expanding which is expanded including a region corresponding to the bulged part to be formed in an expanding and forming stage, a bulged part is formed by pushing out a wall in the above region of the expanded part from the inside with a cam die 23. At this time, the cam die 23 is pushed out by forcing in cam pushing dies 24, 25. After that, by reducing the expanded part except for the bulged part A, the tubular parts having the bulged part in the middle part is obtained. COPYRIGHT: (C)2004,JPO&NCIPI
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