Abstract: Disclosed are a motor control circuit and a control method. The control circuit includes: a power supply; a drive circuit; a pulse width modulation (PWM) signal generation circuit; a controller; and a reverse electromotive force detection circuit. The power supply is connected to the motor through the drive circuit; the drive circuit is connected to the controller through the PWM signal generation circuit; the controller is configured to control the drive circuit by changing a PWM signal frequency; the controller is connected to the motor through the reverse electromotive force detection circuit to obtain a reverse electromotive force parameter; the controller stores a correspondence between the reverse electromotive force parameter and the PWM signal frequency; the controller is further configured to receive the reverse electromotive force parameter and send the PWM signal frequency corresponding to the reverse electromotive force parameter to the drive circuit, for driving the motor.

Abstract: The invention provides a roll profile for work rolls for both shape control and free ruled rolling. Each of the work rolls has a tapered end. The curve of respective tapered end is a quartic curve represented by a formula y(x)=a0+a1x+a2x2+a3x3+a4x4, x?[0,Le], y(x)?[0,He]. It is possible to partially eliminate the asymmetric deformation due to the difference between abrasion of the upper and lower rolls. Further, closed type abrasion of conventional roll is changed into open type abrasion and box shaped abrasion of conventional roll is eliminated, which eliminating “cat ear” hole and fulfilling the requirements of free ruled rolling.

Abstract: Disclosed herein is a roll profile for work rolls for both shape control and free ruled rolling. Each of the work rolls has a tapered end. Providing starting point of the tapered end of the rolls being origin of coordinates, the curve of respective tapered end is a quartic curve represented by a formula y(x)=a0+a1x+a2x2+a3x3+a4x4, x?[0,Le], y(x)?[0,He]. Because the transition between the tapered end and the roll body is smooth, asymmetric deformation due to the difference between abrasion of the upper and lower rolls is eliminated, which reducing wedged shape of strip and reducing unstable rolling due to asymmetrical strip stresses caused by the axial shifting of the roll.