How to solve the tension control system? From control to drive

The twisting machine is also called the twisting unit, which is the subsequent rope forming process in the metal products industry. It combines multiple rigid wires or aluminum wires according to the twisting distance requirements and rope diameter requirements of different processes to achieve multiple strands in order. Combined into a rope, it is widely used in industrial and agricultural applications such as oil drilling, power transmission, ship lifting, loading and unloading, and elevator lifting.

After research and analysis, it is found that the tension control of the steel wire or strands during the twisting process of the steel wire rope has an important influence on the quality of the steel wire rope. On the other hand, winding control is often seen in the industry. For example, in the production process of papermaking, printing, textile, wire and cable, metal strip and wire, the tension on the product during the unwinding and rewinding of materials and the intermediate processing The quality of the product is very important, and constant tension control of the material is required during the production process.

In the coiling system, a suitable tension control system can make the coil maintain a constant tension during the dynamic processing process, so that the product will not cause processing quality problems due to tension changes, and at the same time can ensure the normal operation of the system.

NiMotion combined the product features and advantages of integrated servo motors and motion controllers to design mature and complete synchronous control and constant tension control solutions to provide mature, stable and complete control solutions for the core technical difficulties that have plagued customers for a long time.

The following introduces the application of the integrated servo motor and EtherCAT bus motion controller of Limaison's products and technology in the tension control of the wire rope twisting machine, and solves the technical problems of servo motor synchronization control and constant tension control.

Traditional twister tension control solution

At present, most of the twisting machines produced at home and abroad adopt passive pay-off and mechanical tension control methods. Traditional friction elements, such as brake bands, brake shoes, brake wheels, etc., are used in the pay-off spool. The frictional resistance torque generated between the components is used to adjust the speed of the I-shaped wheel to control the tension of the steel wire. This tension control method that generates resistance through the damping rope or brake shoe has a simple structure and the generated braking torque is constant. The wire tension increases with the decrease of the radius during the pay-off process, and cannot be kept constant. It must be stopped when adjustment is required.

The traditional constant tension control method is mainly based on PID control. At present, the relatively novel control methods at home and abroad are all improved on the basis of PID control, such as fuzzy adaptive PID control with adjustment factors, neural network PID control and so on. Theoretically, these algorithms compensate to a certain extent the problems of traditional PID control, such as untimely adjustment and insufficient stability. However, in actual engineering applications, although the complexity of the algorithm has increased, it has not fully considered the changes of other influencing factors, and only adjusted according to the output error, resulting in the problems of low precision and high delay in its control. Therefore, these algorithms are different from traditional PID The comparative advantage of control strategy is not obvious.

NiMotion technology twister tension control solution

Based on the servo tension control method of Limax twister, it includes the following steps:

1. Obtain the actual tension at the detection point from the tension detection point sensor in the tension control production line

2. Pre-set the value of the given amount of tension in the motion controller, based on the actual detected tension and the given amount of tension to form a deviation

3. Combine the proportional P, integral I and derivative D of the deviation to form a control variable through a linear combination to control the controlled object (the armature current of the actuator of the constant tension control system)

Advantages of application cases:

1. It adopts integrated servo motor (integrating permanent magnet synchronous motor, encoder, and servo drive in one) and supports EtherCAT/CANopen bus servo control. It has the characteristics of small size and simple wiring. There is no need to add additional electrical cabinets in an industrial environment, simplifying the field wiring environment.

2. The electric energy generated by the permanent magnet synchronous servo motor driven by the power source motor is fed back to the battery for charging, which realizes energy saving, saves the cooling system in the prior art, and reduces the device cost.

3. Using EtherCAT bus, EtherCAT embeds its messages into standard Ethernet data frames (forms EtherCAT data frames). The adjustment of tension is more agile and rapid and the bus topology is simple, easy to troubleshoot, and can be expanded to more axes, which can make the system online maintenance and update, with high real-time performance, more stable performance, and correspondingly faster, achieving 1ms response cycle and 5% Tension fluctuations.

4. The low-voltage integrated servo motor is adopted, which has higher safety in the on-site industrial production and effectively protects the personal safety of the operators.

5. Use the encoder of the motor to measure the change of the coil diameter in real time to adjust its own braking torque, so that the constant tension control is more stable, accurate and fast, and effectively ensures the winding more stable, so as to avoid wire breakage Happening.