| 摘要 |
PURPOSE:To form a coiled bushing of high out of roundness with simple working means by cutting a plate material of a width corresponding to the length of an intended bushing obliquely at a prescribed angle with respect to the side edge, pressing and coiling the cut piece and forming the bushing in such a way that the butt end parts thereof contact with each other tightly and spirally. CONSTITUTION:A belt-like steel plate 1 having a width corresponding to the length of an intended bushing and a required thickness is inclined at a prescribed angle alpha with respect to the side end thereof and is cut at equal intervals, whereby plate pieces 2 having a parallelogram are obtained. The cutting intervals of the pieces 2 are set at the size corresponding to the circumferential length of an intended coiled bushing 10. Plunger punches are opened, and the piece 2 is first bent is a U shape along the short side thereof; thereafter both ends assuming an acute angle are coiled, whereby the piece is formed to a cylindrical shape and the coiled bushing 10 is obtained. The bushing 10 has joined end parts 11, 11 in a tight contact state and the butt parts thereof 12 appear spirally, thus providing high out of roundness. |
