| 摘要 |
PURPOSE:To obtain a shaft which is lightweight and has good shape and dimensional accuracy with less man-hour for working by blanking the bases of groove parts by pressing to a drawn pipe which is formed by forming preliminarily groove parts to a round pipe to punch a groove hole then providing continuously stepped fixing ends. CONSTITUTION:Both upper and lower side faces of a drawn pipe 10 mentioned above are recessed to a sectorial shape toward the central part to form groove parts 11, 12 having the sectional shape in which the outside surface side is wide and the base side is narrow. The respective bases 11a, 12a are pressed to each other to provide a closed part 13. The part 13 is blanked with a blanking die 19c to form a narrow communicating hole 20, thereby forming a groove 30 for setting a belt which is wider on both sides and is narrower in the central part. Both upper and lower side parts of the material 10 at the part having a length l1 are then fitted and held to round blocks 21A, 21B and both right and left side walls 14, 15 are pressed by press dies 22A, 22B to flatten the walls 14, 15. The front side part in the part l1 and the rear side part in the central part are flat crushed and pressed by pressing by press dies thereto from both upper and lower directions. The pipe is then subjected to one or two stages and the shaft of the prescribed length which has fixed shaft parts 24, 29 at both ends and of which both side parts expand outward along the axial center in the central part 40 having the diamter larger by one side is obtd. |
