PURPOSE: To improve productivity and rollability by selectively rotating caliber rolls forward or backward during rolling of a pipe stock and providing a rotating device for the pipe stock and a driving device for axially moving a mandrel bar.
CONSTITUTION: The mandrel bar 13 is disposed at the center of a pair of the caliber rolls 11 to form a rolling region for the pipe stock 12 with the rolls 11. A roll motor 14 drives the rolls 11 to selectively rotate the same forward or backward via a control device 24 during rolling of the stock 12. The stock 12 is elongated to the reduced thickness between the rolls 11 and the bar 13 and thereafter the stock 12 is rotated 90° by a pipe stock rotating motor 19 in the 1st pass. After return rolls 23 are brought near to each other, the rolls 11 are rotated backward and at the same time a bar driving motor 15 is operated to move the bar 13 by which the pipe stock is again elongated to the reduced thickness. The wear of tools is thereby decreased and the productivity and rollability of the pipe are improved.
KASAHARA HIROJI
IMAE TOSHIO
TAGUCHI YOSHIO
| JPS51132158A | 1976-11-17 |