PURPOSE: To improve the correction effect for wall thickness deviation of a metal tube by installing a plug positioner at a prescribed position in the rolling direction and rolling a stock for a prescribed period after a rolling start with the plug located at a position bringing good biting condition.
CONSTITUTION: A plug 2 is installed between slant rolls 1a, 1b of a slant rolling mill and a mandrel bar 3 jointed with the plug 2 is connected to a cylinder 5 through a coupling 4. Rolling is performed for a prescribed period of time before and after the peripheral surface of a hollow shell 6 is brought in contact with the roll surface of the rolls 1a, 1b with the plug 2 located at a position preventing insufficient biting. After the rolling, another rolling is performed with the plug 2 is shifted by the cylinder 5 to a position in the vicinity of the outlet side of the mill. Thus, rolling is performed to prevent troubles caused by bucking in a biting time and the correction effect for wall thickness deviation of a metal tube is improved because the rolling is performed after shifting the plug 2.
KIRIMOTO TAKESHI
URAYAMA TAKESHI
| JPS5496462A | 1979-07-30 |