Development of Walking Control Technology in Hot Strip Rolling

Abstract

Synopsis : This paper describes walking control suppressing the lateral unstable movement of the strip in a hot strip finishing mill. The conventional method for controlling walking is well known as "load difference method", in which the measured load difference between the drive and operator sides of the rolling stand is fed back to the roll gap slant reference. However, analyzing the relationship between the feedback control gains of load difference and control effects, we found that the conventional method had a defect that the control effect extremely decreased, as the strip width became wide. Therefore, we developed a new control method that the manipulated value of the roll gap slant was determined based on the strip position measured by a newly developed measuring instrument. In this method, because the strip position sensor is equipped at the entry side of the controlled rolling stand with some distance, the measured strip position is not equal to that at the rolling stand, which is the controlled variable. We overcome the difficulty by applying the model predictive control having the function to predict a future value of the controlled variable and optimizing the manipulated value of the roll gap slant. The effectiveness of the new control method has been demonstrated in an actual plant.

Development of a Shape Meter Employing the LED Dot Pattern Projection Method for a Hot Strip Finishing Mill

“…1) The interstand strip position sensor, which measures the sudden rotation of the strip tail end, was applied to the leveling control of the rolling stand to reduce the strip walking trouble. 2) The fountain pyrometer, which measures the strip temperature in the cooling zone, was applied to cooling pattern control to improve the temperature accuracy and mechanical properties of the strip. 3,4) For further improvement of these productivity and quality, it is effective to control the strip to be accurately flattened at hot rolling.…”

Effect of Clearances in Mill Stands on Strip End Motion During Finishing Rolling

“…An analytical model describing the dynamic equations of motions of the strip during a stable finishing process was introduced in [4]. Finishing parameters such as reduction, mill modulus, roll deformation, tension of the strip, and restraint moment were considered as variables that would affect the strip motion.…”

Development of FEM Simulator Combined with Camber Reducing Output Feedback Fuzzy Controller for Rough Rolling Process

“…In real situation, although the off-center value at the rolling position cannot be measured, it can be estimated by using simple equation with small error deviation based on the measuring device (i.e., CCD camera) located upstream of rolling position. 31) Although this configuration is recommended in 31), various modified methods can be applied to get yc. It should be noted that another measuring device (i.e., off-center meter or CCD camera) is assumed to be located downstream of the roll axis with some distance apart ( Fig.…”