| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that when a cam shaft is manufactured by inserting a hollow tube stock into a cam piece made of sintered alloy and bulging then to fit them each other, machining is required for the cam piece and manufacturing cost of the cam shaft is raised accordingly. SOLUTION: A hollow tube stock 5 inserted into the inside of hollow bodies 6a, 6c made of a plastically workable bearing steel is contained in the inside of a bulging die 3, a bulging is conducted to the hollow tube stock 5, the outer shape of the hollow bodies 6a, 6c is formed to a prescribed shape by sticking the hollow bodies 6a, 6c to the inner face of the bulging die 3 further, the hollow tube stock 5 and the hollow bodies 6a, 6c are fitted. By this method, a cam shaft 9, which has a rotation shaft 11 and cam pieces 10b, 10c fitted to the outer peripheral face of the rotation shaft 11 and is formed by forming the outer shape of the cam pieces 10b. 10c by bulging, is manufactured.
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