Tension Control of Paper Machine Rewinding and Unwinding System

The tension control of the rewinding and unwinding system of the paper machine, such as the rewinding machine and the off-machine coating machine. There are two forming methods for papermaking, namely flat paper and web paper. Due to the large number of high-speed printing presses, the demand for web paper is increasing day by day. Compared with flat paper, web paper can increase the speed of paper machine. However, the paper machine's processing of web paper is a relatively complicated process, especially in the center winding process. With the continuous increase of the roll diameter, the speed of the web roll must be continuously reduced while ensuring the paper web The tension is relatively stable. Therefore, for the winding and unwinding system, the tension control is the core technology, and it is also the difficulty of frequency conversion speed regulation.

For such a complicated paper machine tension control system, the frequency conversion technology must be able to overcome the following 4 technical problems:

1. Simplify the mathematical model of the complex AC asynchronous motor.

2. Taking into account the delay and overshoot of the tension feedback signal.

3. Describe the dynamic parameters of the winding tension control process as a time-varying function.

4. Ensure that the tension closed loop has high anti-fluctuation ability and good instant adjustability.

At present, the following two control methods are most commonly used in coiling:

1. Speed control winding (SPW), using PID to correct the speed setting through the tension feedback of the load cell or the position feedback of the adjusting roller.

2. Current-controlled winding (CPW), using PID to adjust the tension setting, can be applied to the central winding method, this type of control is generally open loop.

The paper machine frequency conversion control system with tension control is generally composed of modules such as diameter, compensation, torque and speed calculation.