| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a product uniformly forming a serration even at near the boundary with a tapered tube without needing the excessive product cost, in the forming apparatus and the forming method for arranging the serration on the inner surface in a small diameter portion of a hollow tube. <P>SOLUTION: After performing a primary formation arranging the serration to a range coming to the boundary with the tapered tube 33 on the inner surface of a first small diameter tube 31 of the hollow tube 30, a secondary formation (finish formation) for shaping the serration generating the distortion is performed. The primary formation is performed by using a first die 280 assembled so as to be slidable in a hollow die case 210 and a core 220 for forming the serration part 221 on the outer peripheral surface at the tip end part. The secondary formation is performed by using a second die 400 having smaller inner diameter than the first die 280 to push in a mandrel 420 into the tapered tube 33 in the hollow tube 30. <P>COPYRIGHT: (C)2007,JPO&INPIT |
