| 摘要 |
PURPOSE:To prevent the decrease in working efficiency occuring in the cutting in the bottom part of a pipe and to improve the safety of operation by advancing a mandrel into the through-hole of a backing plate thereby punching the bottom part of a bottomed finish pipe obtd. by molding with the final horizontal press. CONSTITUTION:A bottomed blank pipe P1 which is obtained by Ehrhardt's piercing process is inserted onto an ironing mandrel 3 with a horizontal press and is passed through dies 4, whereby a finish pipe P2 having a prescribed outside diameter OD and a wall thickness (t) is finally obtained. Thereafter, a backing plate 5 with a through-hole 5b is installed in place of the dies 4 or in front of the dies 4 and the bottom part PB of the pipe is brought into contact with the plate 5. When the mandrel 3 is advanced forwared from the plate 5, the part PB is punched through by the shearing force, and the bottomless pipe is obtd. Since the temp. of the part PB is usually about 700-1,000 deg.C, the bottom is punched easily. |
