| 摘要 |
PURPOSE:To prevent generation of troubles in the elongator mill, by controlling rolling conditions of the cross helical rolling mill, at again piercing and elongating the hollow rolling blank manufactured by the cross helical rolling mill, with the elongator mill. CONSTITUTION:The seamless pipe is manufactured from the round billet, etc., by the cross helical rolling mill, and this seamless pipe is again pierced and elongated by the elongator mill. Hereupon, when the seamless hollow pipe blank is manufactured, the range of possible rolling conditions satisfying formulas I, II, III, for giving conditions to prevent generation of the incorrect biting and the rear jamming, and the formula IV for giving conditions to prevent the tear of the rear end at piercing the extremely thin walled pipe, and the condition to lessen generation of the thickness deviation, are selected in order to prevent the generation of troubles at passing the elongator mill; and the rolling conditions like as the diameter of plug 14, the gap of rolls 12, the forward slip of plug 14, the clearance of guide shoes 18, etc., of the cross helical rolling mill are determined so as to set the rolling conditions at approximate middle of the range of possible rolling conditions. |
