| 摘要 |
PURPOSE:To form a light weighted gear shaft by setting a gear, shaft core, and shaft hole on the shaft outside, partly pressing the outside of a small shaft part formed in both sides of the gear to form a spline part, and reducing the shaft hole. CONSTITUTION:A mandrel 3d is inserted into a shaft hole 1a of a long cylindrical billet formed from a short cylindrical billet, the long billet is pressed by an upper die 3c and a lower die 3b of an extrusion die 3B to make the outside diameter of an end of the long billet small and the long billet is named as a billet M3. Then, the billet m3 is reversed so that another end of the M3 is also made small. The billet M3 and the mandrel 3d are inserted into a spline forming die 3D and are passed through a spline projection 3p by a lower die 3b and an upper die 3c to form a spline 1e on the outside of the M3. In that time, recess parts of a shaft side spline is pressed from outside and swells into the shaft hole 1a to make a billet M5 having the reduced inner diameter. A speed changing gear 1b is engraved on the central large diameter part of the M5, is treated by a surface hardening, is subjected to a chemical polishing, and is finished to a prescribed dimension.
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