| 摘要 |
PURPOSE:To form a stepped screw rod having threaded part of large diameter by inserting a cylindrical body into a small diameter screw rod inserted into a die, pressing in the direction of the die, and reducing the cylindrical body to fix it firmly to the screw rod, and thereby forming thread on the outer periphery of the cylindrical body. CONSTITUTION:After inserting a side 1a of a screw rod 1 into a die 2, a cylindrical body 3 provided with a through hole 3a having diameter a little larger than the screw rod 1 is inserted in a side 1a. A punch 4 is advanced in the direction of the die a holding the cylindrical body 3 in the same line with the screw rod 1, and 2 side 1a of the screw rod 1 and a side 3b of the cylindrical body 3 are placed on the same face. Then, the screw rod 1 and cylindrical body 3 are pressed by advance of the punch 4, and another side 3C of the cylindrical body 3 is reduced to small diameter, and a part of the cylindrical body 3 is fixed firmly to the screw rod 1. The punch 4 is inserted into the die 2 and the cylindrical body 3 is fixed to the screw rod 1 in a body, and after taking out from the die 2, thread 3d is formed on the outer periphery of the cylindrical body 3 by rolling or cutting. |
