JPS57199506A - Production of large diameter seamless pipe - Google Patents

Abstract

PURPOSE:To improve the roundness of the sectional shape of products by driving a pair of rolling rolls respectively independently, and controlling the rotating speeds of the respective rolling rolls in such a way that the central axial line of a cylindrical rolling blank material under rolling is located on the plane inclusive of the central axial line of the rolling rolls. CONSTITUTION:A rolling roll 2 on an inside circumferential side and a rolling roll 3 on an outside circumferential side which roll a cylindrical rolling blank material 1 are connected to respectively independent driving devices 4, 5, and the rotating speeds of the rolls 2, 3 are so controlled by a controller 6 that the central axial line of the material 1 under rolling is located on the plane inclusive of the centerline of the rolls 2, 3, thereby performing rolling. For example, if the central axial line of the material 1 deviates by a deviation quantity delta to the rolling outlet side, a material position detector 9 detects this, and emits a detection signal to the controller 6. Upon receiving this, the controller 6 instructs the devices 4, 5 so as to decrease their rotating speeds.