| 摘要 |
PROBLEM TO BE SOLVED: To provide an extrusion method and an extrusion device capable of suppressing a droop of a large diameter part of a spline. SOLUTION: The surface roughness Rz1 of a land 7 on the side for forming a small diameter part of a spline in a die 4 is set to be coarser than the surface roughness Rz2 of a land 9 on the side for forming a large diameter part of the spline. Therefore, the friction between the land 7 on the side for forming the small diameter part of the spline and a work is increased during the extrusion, and the plastic flow of the work in a vicinity of the land 7 is suppressed. Thus, the plastic flow of the work in a vicinity of the land 9 on the side for forming the large diameter part of the spline toward the work in a vicinity of the land 7 on the side for forming the small diameter part of the spline is suppressed, and generation of droop of the large diameter part of the spline can be prevented. COPYRIGHT: (C)2007,JPO&INPIT
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