Free-tension setup system for bar rolling based on fuzzy inference

摘要

Precision rolling of a bar with a nominal diameter tolerance of ±0.1 mm has been put into practical operation. The precision bar rolling system comprises two parts: an interbillet dimensional control system consisting of a finishing size setup based on influence coefficients and a profile meter signal processing and a free-tension setup based on fuzzy inference, and an inbillet dimensional control system with multivariable control consisting of tension control and automatic gauge control (AGC) This paper deals with the interbillet dimensional control system. A free-tension setup was developed as follows. The difference in the rate of change in the rolling torque-load (=load parameter) of the No.i+1 stand between before and after the tail of the rolled material leaves the No.i stand is proportional to the interstand tension and is controlled to zero. Since large fluctuation of the rolled material temperature weakens the correlation between the rate of change of the load parameter and that of the interstand tension, the roll speed correction to be made for the next billet was determined based on fuzzy rules.