| 摘要 |
The present invention relates to a method for manufacturing a serration merging specification for a pinion used in a steering device. More specifically, the present invention relates to the method for manufacturing the serration merging specification for the pinion which is difficult to be manufactured by a thread rolling method since a serration is merged. The method for manufacturing the pinion according to the present invention is to form a merged serration on a forth diameter surface by pushing a shaft for processing into a multi-stage mold, wherein an upper guide mold, a center guide mold and lower molds are coaxial-aligned. The upper guide mold has a first guide hole of a first diameter. The center guide mold has a second guide hole of a second diameter smaller than the first diameter on an upper part, and has a third guide having a third diameter smaller than the second diameter on a lower part of the second guide hole. The lower molds have a serrated protrusion part for merged serration processing on a surface of a processing hole having a fourth diameter smaller than the third diameter in an inside. The shaft for processing has a first diameter part having a diameter corresponding to the first diameter, a second diameter part having a diameter corresponding to the second diameter, a third diameter part having a diameter corresponding to the third diameter, and a fourth diameter part having a diameter corresponding to the fourth diameter. |
