CALCULATING METHOD FOR ADVANCING AND BACKING RATIOS IN SHEET ROLLING

PURPOSE:To accurately measure advancing and backing ratios by comparing a deviation in rotation numbers of a rolling roll corresponding to an additional number to the number of rotations of winding and rewinding reels and a difference in reel diameters increasing or decreasing in accordance with the additional number to both above reel rotation numbers. CONSTITUTION:Pulse generators 5, 7 are installed on rotation shafts 6, 8 of a rolling roll 1, tension reel 4, and payoff reel 3 to generate signals proportioning to the number of rotations of the reels 4, 3; a deviation in rotation of the rolling roll against one rotation of the reel 4 or 3 is detected by comparing the above signals with a signal proportioning to the number of rotations of the rolling roll. An advancing or a backing ratio is calculated by a prescribed equation based on a difference between the number of rolling roll rotations at different winding numbers of the reel 4 or 3, a difference between diameters of the reels 4, 3 found based on sheet thicknesses in the inlet and outlet sides of a rolling mill, and a rolling roll diameter. Thus, a forwarding and backing ratios are accurately measured.