CONTROL DEVICE FOR ROLLING MILL

PURPOSE:To improve rolling accuracy by correcting the influences of the thermal expansion and abrasion of rolling rolls and plugs. CONSTITUTION:Target wall thickness value T, target elongating length l, and target diameter value D of product pipes, specifications eta of blank materials, and specifications phi of rolling mills are inputted to an arithmetic unit 20 for set values. The unit 20 calculates rolling reduction F and plug forward slip L and outputs the same to an arithmetic control device 30 for rolling down positions and an arithmetic control device 40 for forward positions. An arithmetic unit 10 for correction values takes number (n) of rolling pieces, roll changing specifications phi, ambient tep. Tm, rolling time tr and rolling downtime ti, and calculates the correction value DELTAF of the rolling reduction and the correction value DELTAL of the plug forward slip. The value DELTAF from the unit 10 and the rolling reduction F from the device 20 are taken into an arithmetic control device 30 for rolling down positions, which device calculates drawing down positions and controls the gaps of rolling rolls. Further, the value DELTAL from the unit 10 and the forward slip from the unit 20 are taken into the device 40 which calculates forward positions and controls the position of a plug 2.