| 摘要 |
<p>PURPOSE:To make approximately uniform the wall thickness of the hollow cylinder over entire circumference, by rotating at least one of piercing rolls most adjoining to the thin walled part in the hollow cylinder to be formed from the work at peripheral speed higher than that of other piercing rolls. CONSTITUTION:In case of forming the hollow cylinder from the work by the press roll piercing machine, the main rolling work is carried out by the piercing rolls 3, 3', possessing a long circular arc plane, and the spread part in the breadth due to the first rolls 3, 3', is reformed with the piercing rolls 4, 4', possessing a short circular arc plane. Hereupon, if the lower side of the cylinder is always apt to be thick, the peripheral speed of the upper piercing roll 3 is made higher than that of the lower roll 3'; hereby, the generation of thickness deviation is prevented, or the thickness deviation caused around the tip end of the cylinder is improved toward the tail end of the cylinder. In the meantime, when the thickness deviation is caused on the left and the right sides, the peripheral speed of the roll on the side of the thin walled part is increased in order to improve the thickness deviation; or when the thick wall is caused at the boundary between the rolls 3' and 4', the peripheral speed of the roll 3 is increased from that of the roll 3', and the peripheral speed of the roll 4 is increased from that of the roll 4', and the thickness deviation can be improved.</p> |
