| 摘要 |
PURPOSE:To execute forming with a high efficiency without generating a chip, by inserting and holding a discoid base material so as to be rollable by a pair of rack tools having a rolling tooth part, and using a part of the rolling tooth part as a shaping part of particulars which are engaged with a worm wheel which is formed. CONSTITUTION:A pair of rack type tools 16, 18 are provided in a state that a disk- shaped base material 14 is inserted and held so as to be rollable, and as for the tools 16, 18, a tooth part 20 and a tooth part 22 are formed in one side and the other side, respectively. The tooth part 20 becomes a bitten part, and a large irregularity is formed in the discoid base material 14 by applying a large driving fore to the outside periphery of the discoid base material 14. The tooth part 22 is a shaping part for forming exactly this formed irregularity to a worm wheel of a desired size, and becomes particulars to be engaged with the formed worm wheel. In the first half part of forming, the tooth part 20 executes a swell of the tooth and a generating deformation to the outside periphery of the base material 14, and in the latter half, a finish sizing is executed by the tooth part 22. In this way, since the worm wheel is manufactured by a plastic deformation, no chip is generated, and the working efficiency is raised.
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