| 摘要 |
PURPOSE:To minimuze the substantial length of uncorrected part by making correction of the end part of a tube including an upset part at lower speed than feeding speed at the time of correcting the intermediate part of the tube. CONSTITUTION:In correcting an upset steel tube, the front upset part Uf an the neck Nb of rear upset part Ub are detected and correction for the front tube end part including the front upset part Uf and front neck part Nf and the rear tube end part including the rear upset part Ub and rear neck part Nb is made at lower feeding speed than that for correction for the intermediate part of the tube. The rolls of correcting rolls R1, R2, R3 are opened and closed during this slow-speed correcting. By this way, the part of imperfect biting in the neck part of upset part can be shortened and the part where glassing can be made is made greater. Thus, the length where correction including bending is not given can be minimized. |
