CONTROLLING METHOD FOR ROLLING WORK BY REELING MILL

PURPOSE:To prevent the variation in the wall thickness of a pipe, and to improve the yield, by controlling the diameter of the pipe to an aimed size of a rolling pass of a sizing mill, while correcting the expansion of the pipe due to a rolling work of a reeling mill, correspondingly to a thickness deviation caused by a plug mill's rolling work. CONSTITUTION:An arithmetic control unit 21 receives following information; material temperature T measured by a thermometer 20; information about the rolling torque Trq sent from torque meters 16, 16' attached to spindles 22, 22' of rolling rolls 10, 10'; wall thickness tp of a blank pipe measured after a plug mill's rolling pass and before being fed to a reeling mill; and outer diameter DP of the blank pipe. The unit 21 then outputs a reduction control signal DELTAE on the basis of said information to a reduction controller 19 which thereby practices the position control for the rolling rolls 10, 10'. Hereby, the roll gap E of rolling rolls 10, 10' is adjusted correspondingly to a difference (DELTAtA-DELTAto) between an aimed wall thickness reduction DELTAto and the actual reduction DELTAtA in the wall thickness. For DELTAtA-DELTAto>0, the gap E is increased, and for DELTAtA-DELTAto