| 摘要 |
PURPOSE:To inhibit the relief of a material in a center direction from a corner part in the bottom part by forming a projection part on a male die or female die surface constraining the bottom part of a toothed drum and interposing this projection part in said bottom part material. CONSTITUTION:The die for drawing is composed of the female die 11 consisting of a male die 12, fixed female die 11a (die) and movable female die 11b (knockout). The semi-finishing product 13 preworked in a cup shape is pushed into the male die 12 and female die 11a to perform the forming of a toothed drum 13. At the initial step, the growth of a tooth profile and the bending of a cylindrical part are promoted and the bending of the cylindrical part and a tooth profile are completed by reaching the final step from the ironing stage of the medium step. The projection part 17 of the male die 12 or female die 11b is interposed to a bottom part 16 and said bending and tooth profile forming are performed with limiting the relief of the bottom part material in the drum center direction. The thickness reduction of the corner part is thus inhibited, the drop of the tooth profile end part is prevented, the thickness is secured and the strength is secured as well.
|
