| 摘要 |
PURPOSE:To shorten uncorrected length allowance at front end and tail end of an upset steel pipe by correcting a mother pipe making the open part of the front side roll to which upset parts of the front end and tail end advance as an amount of upsetting. CONSTITUTION:An upper roll 2 is opened at full stroke L, and a lower roll 3 and an offset roll 5 are opened at limited setting stroke l, l+S. After detecting the front end of the pipe at the entrance of a pass line, each roll is operated, and the pipe is rotated and sent by a set of closed front rolls, and each roll is closed successively when the front end of the pipe passes. Rotating bending action is applied on the mother pipe 6A from the time when the tip of the pipe comes to the position shown by solid lines. Consequently, uncorrected length allowance at the tip of the pipe can be made very short. At the tail end part, front side rolls 2, 3 are opened before arrival of a tail end upset part 6B'. As the roll 3 is opened by stroke l, rotating bending action is applied on the mother pipe 6A while the part 6B' is passing on the roll 3. Consequently, uncorrected length allowance can also be shortened remarkably at the tail end. |
