| 摘要 |
PURPOSE:To improve productivity considerably without requiring the stage for reducing the bore at the preceding end of a blank pipe in a push bench system rolling method of Ehrhardt roll type by driving the caliber rolls of an end biting stand for the blank pipe successively. CONSTITUTION:After a mandrel bar 18 is inserted into a bottomless blank pipe 26 after piercing, the pipe is forced into a roll type push bench 24 having many caliber roll stands of plural roll types, whereby the pipe is reduced and elongated continuously. In this stage, the caliber rolls 24a of the end biting stand of the pipe 26 is forcibly driven successively in the rolling direction. More specifically, in the stage of forcing the bar 18 into each stand, first the rolls of the 1st stand 24-1 into which the preceding end of the pipe 26 is bitten first is kept driven so that the bar 18 then the pipe 26 are bitten therein. Thereafter, the rolls of the 2nd stand 24-2 are kept driven to bite the bar and the pipe similarly. After biting, the stand 24-1 is not driven or is kept driven auxiliary. In such a way, the pipe is rolled successively. |
