| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for reducing the diameter of an end part of a hollow rack bar by which the number of processes of working for reducing the diameter of the end part of the hollow rack bar is decreased. SOLUTION: In this method, the diameter of the end part 4a on a cylindrical other end side portion 4 of a hollow bar 1A on the one end side portion 3 of which a rack 2 is formed is reduced, and the following bar 1A is taken as an object to be worked. In the bar 1A, recesses 12, 15 are formed between rack teeth 2a, 2b located on both ends of the rack 2 and adjoining portions 11, 14 having inclined portions 11a, 14a opposing to the tooth side-faces of these teeth and continuous to the both ends of the rack 2. First, the one end side portion 3 is held by a jig 21 including a jig member 22 having a pair of projecting parts 25 which are brought into contact with the tooth side-faces and the inclined portions and fit into the recesses and a jig member 28 which performs die-clamping and die opening with respect to this member 22. After that, the diameter of the end portion 4a is reduced by press fitting a compression die 31 having an inside diameter smaller than the diameter of an outer periphery on the outer periphery of the end portion 4a of the portion 4 of the side of the other end projected from the jig 21 up to the press-in depth M preliminarily determined with the rack 2 as a reference. COPYRIGHT: (C)2009,JPO&INPIT
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