| 摘要 |
A worm is formed by rolling to reduce the number of processing steps while ensuring the worm accuracy satisfactorily. A work material is positioned between a first rolling die ( 100 ) and a second rolling die ( 101 ) by rotation of the rolling dies and a servomotor ( 76 ) for feeding the work material. When the lead angle of a worm is large and there is a large difference between the finished diameter and the blank diameter, the lead angle changes during the progress of rolling process, resulting in occurrence of through-feed. A slide plate ( 55 ) is freely slidable on a slide ( 53 ). Therefore, when through-feed occurs owing to the lead angles of the first and second rolling dies ( 100 ) and ( 101 ) and the workpiece, the slide plate ( 55 ) slides freely, and this is detected with a detecting sensor. The rotation of the first and second rolling dies ( 100 ) and ( 101 ) is stopped. Then, the first and second rolling dies ( 100 ) and ( 101 ) initiate reverse rotation, and at the same time, the slide plate ( 55 ) also initiates movement in the reverse direction. Thus, rolling is started. Thereafter, similar processing is repeated to perform rolling.
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