| 摘要 |
PROBLEM TO BE SOLVED: To improve the operation efficiency by forming a teeth at the periphery of a disclike material, the thickness of which is increased by performing a rotation roll forming, wherein a cutting treatment process is reduced as a result that a clearance groove is formed due to increase of thickness. SOLUTION: An in-low groove W1 having a bottom is formed by applying an in-low half punching at a center part of the disclike material W with a press forming. A rotation roll forming is applied to a periphery of the disclike material W as a center part of the in-low groove W1 so as to increase the thickness of the periphery W3 and form a clearance groove C4 at inside of the disclike material W. A reference hole C2, a light weight hole C3 and the like are formed on the disclike material W by punch processing. A turning is performed to the inner diameter of the reference hole C2 for reaming. The periphery W3, whose thickness is increased, is processed with HOB gear cutting for forming the teeth at periphery of the disclike material W, to which a cam chain is hooked around. Then, a carburizing treatment, a shot treatment and a reference hole inside diameter finishing treatment are performed for obtaining a cam sprocket.
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