Abstract: A current control method and a motor control circuit are provided. The motor control circuit includes a first rectification circuit and a second rectification circuit connected in parallel between a live wire and a natural wire of a power supply, a sampling resistor, and a controller connected to the second rectification circuit. The first rectification circuit is connected to the motor. The current control method include obtaining a periodic waveform signal of a bus voltage; collecting a bus current value through the sampling resistor; sampling the periodic waveform signal for a plurality of times; linearly fitting multiple voltage values obtained at a plurality of sampling time points to obtain multiple slopes; obtaining a power frequency according to the multiple slopes; calculating a compensation current value according to the power frequency; and generating a control signal according to the compensation current value and the bus current value.

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.