Tension Control System And Application Of A Copper Slitting Line

This paper presents the control system design and application to a copper 1250 slitting line, which introduces the units, composed of the equipments and simply explains the every parts'function. According to the technology and quality requirements, the selection of electrical control equipments is analyzed and compared. The communication network for logic control and AC drive control are selected as the Profibus network, as well as the MPI network for man-machine interface operation. The AC drive technology using common DC bus and three type brake modes are analyzed and the common DC bus and brake resistor approach are finally applied to the AC drive system. Siemens 6SE70 convert optimization commissioning and network configuration are introduced, the vector control was achieved by the optimization.Because the speed and torque control are coupled each other, a constant tension control depending on the constant speed control are used. This paper compares and analyzes several methods to the recoiler diameter measurement, and the slitting line recoiler diameter is calculated by an area equivalence scheme, and speed mode is selected in the slitting shear and recoiler with master drive mode of Siemense vector control with encoder.This slitting line includes two types of tension control, the one is slitting strip with looper, tension is set up between the RB21 strap station and the recoiler, and the advantages and disadvantages of the RB21 are analyzed. Another tension is set up between the tension roll and the recoiler with no looper, it is an indirect and open loop control mode. The recoiler motor works in speed mode to keep constant linear velocity. The tension roller works in torque mode, that is, slave control type of Siemense vector control with encoder, then the tension roller is driven by a given tension, it follows the recoiler velocity. To guarantee strap tower form tightness and flatness strap side, the slitting line has to use tension gradient, such as line type gradient or curve type gradient, two types are compared and finally selects the curve type gradient.How to analyze constant tension, this paper adopts an approximate and qualitative method, that is, an AC motor complex torque formula under vector control is replaced with a equivalent and terse, constant tension formula under maximum torque is introduced. In the slitting line decoiler tension control, the tension fluctuations is caused by many reasons, such as the line acceleration and deceleration, that are avoided by dynamic and static compensation feedforward control, and the fixed inertia of the measurement and the calculated variable inertia are used to the compensation.Some of the control system tuning experiences are also presented, for example digital filter technique is used to eliminate dynamic error of diameter measurement.Finally, the real control process' records are introduced, which are obtained by the oscillograph of Siemense convert software drive monitor, the slitting line control performance is quite good, this is verified by the actual production.