| 摘要 |
To sufficiently secure the width dimension, strength and rigidity of the rack teeth 10, and to realize the light weight construction and the manufacturing method of the rack 8, the rack teeth 10 is formed by plastic working on one side surface in the radial direction of part in the axial direction of a rod unit 9 having a circular cross-sectional shape, and the curvature radius of the portion which is separated in the radial direction from the portion where the rack teeth 10 is formed, is made greater than that of the cross sectional shape of the outer surface of the axial remaining portion of the rod unit 9. For this purpose, as shown in (A) to (B), while a portion in the circumferential direction of part in the axial direction of a material 13 is compressed, the remaining portion in the circumferential direction of this part in the axial direction is formed into a partial cylindrical surface 17 whose curvature radius is larger than that of the outer surface of the material 13, to form an intermediate material 20. Then, as shown in (C) to (D), the rack teeth 10 are formed on the circumferential portion of the axial part of the intermediate material 20. At last, as shown in (E) to (F), sizing is performed to obtain the rack 8. |
