| 摘要 |
PROBLEM TO BE SOLVED: To provide a rack-and-pinion type steering device comprising a rack reduced in the weight but capable of securing bending strength equal or more in relation to a solid rack. SOLUTION: A steel pipe raw material is used for a main body part of the rack 10, and a tubular first rack raw material 10a is formed by cold forging, and a bar-like second rack raw material 10b is inserted into an inner space of a part forming rack teeth 10c, and the rack teeth 10c are formed by cold forging pushing with a teeth-shaped die from the outside. Cross section of the rack 10 is formed into a shape having a swelling part 10d swelling in a direction crossing the axial direction of the rack 10. The rack teeth can be thereby formed without complicated processes, and since the rack teeth part is practically formed into a solid body, the rack 10 strong against the bending stress can be formed. Since the swelling part 10d is formed with the rack teeth 10c, length in the tooth trace direction engaged with a pinion is increased, and a ratio of engagement with the pinion can be improved. COPYRIGHT: (C)2008,JPO&INPIT |
