To eliminate the adjustment or the changing work of the drawing device of a pierced shell with setup change in tube making by automating the drawing device of the pierced shell and making it size-free.
(1) In a piercing mill provided with a device for pulling a plug and core bar out of the pierced shell and device for conveying the pierced shell, the drawing device of this piercing mill is provided with means 11, 12 for restraining the movement of the shell in the same direction as the plug and core bar and means 13, 16 for adjusting the opening degree of these means for restraining the movement of the shell. It is preferable to provide means 18, 19 for mitigating the shock generated at the time of restraining the movement of the shell in the same direction as the plug and core bar on the pulling- out device of the plug and core bar. (2) This method is a drawing method of the pierced shell which is used in the piercing mill and, after only the movement of the shell is restrained by adjusting the opening degree of shell stoppers 11 and the plug and core bar are pulled out of the inside of the shell, the shell is conveyed to the next stage.
YOKOI YOICHI
OISHI TOSHIMITSU
YAMANAKA KODAI
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