Controlling method of wall thickness in stretch reducing mill for steel pipe

TLDR: In this paper, the authors proposed a method to make the wall thickness of a blank pipe uniform by controlling the tension between stands, by detecting the bulge width at the time of stretch-reducing, and controlling the peripheral speed of a roll at each stand basing on the distribution of bulge-width of the pipe in the longitudinal direction.

Abstract: PURPOSE:To make the wall thickness of a blank pipe uniform by controlling the tension between stands, by detecting the bulge-width at the time of stretch- reducing, and controlling the peripheral speed of a roll at each stand basing on the distribution of the bulge-width of the pipe in the longitudinal direction. CONSTITUTION:In a mandrel mill, the distribution of bulge-width in the longitudinal direction, detected by a bulge-width detecting device 11 at the time of elongator-rolling, is transmitted to a bulge-width recording device 12 and then is stored in a host arithmetic device 13. The device 13 calculates to obtain a roll- peripheral-speed controlling pattern in accordance with a calculating formula basing on the distribution of the bulge-width in the longitudinal direction. Then in stretch-reducing a blank pipe by a stretch reducer 14, a driving motor at each stand is controlled in accordance with the calculated controlling pattern of the peripheral speed of a roll through a drive-controlling device 15.