| 摘要 |
PURPOSE:To prevent the occurrence of the internal surface flaw in the shell, by partially changing the inner diameter of the tip of shell before being fed into the plug mill so as to be smaller than the diameter of plug of the plug mill, and by applying the rolling work to the shell. CONSTITUTION:The inner diameter of the shell 2, laid on the pipe end aligning roller conveyer 20, is partially changed so as to be smaller than the diameter of plug of the plug mill; for this purpose, as the upper die 23 is fixed to a specified position, the armlike lower die 22 is elevated by a specified stroke of the hydraulic cylinder 27, and the tip of the shell 2 is pinched between the armlike lower die 22 and the upper die 23; hereby, the tip of the shell 2 is flattened. The shell 2 with thus flattened tip is transmitted onto the trough on the feed-in side of the plug mill. These actions are automated by incorporating them into the automatic remote control sequence. |
