I. Upgrade to a closed-loop tension control system
Using a closed-loop control scheme of vector frequency converter + tension sensor + PLC is the most effective technical path to solve tension fluctuations.
1. Real-time feedback adjustment: The actual tension value is dynamically collected by the tension sensor, and the control system responds in milliseconds, automatically adjusting the motor torque to control fluctuations within ±5%.
2. Automatic roll diameter compensation: Combining encoder data with real-time calculation of roll diameter changes, the speed is dynamically adjusted to avoid tension imbalance caused by increased roll diameter.
3. Recommended configuration: Use frequency converters with built-in tension control modules, such as the Huichuan MD330, to reduce external controller costs and improve system integration and stability.
II. Optimize frequency converter control mode and parameter settings
1. Dynamic switching of take-up/unwinding roles: The take-up side uses torque mode, and the unwinding side uses speed mode. The roles are automatically switched after the roll reaches the end to ensure constant tension.
2. Enable Pre-drive and Taper Compensation Functions: Utilize the "pre-drive" function to automatically match the angular velocity based on the relationship between linear speed and roll diameter, achieving constant linear speed operation; set a reasonable tension taper (e.g., tighter inside, looser outside) to prevent inner layer damage or outer layer sagging.
3. Fine-tune PID Parameters: Optimize the proportional (P), integral (I), and derivative (D) parameters in the PLC to avoid overshoot or slow response, improving system dynamic stability.
III. Strengthen Mechanical System Maintenance and Calibration
1. Check Guide Roller Parallelism and Surface Condition: The parallelism deviation of the fabric roll and guide roller should be ≤0.5mm/m, with smooth, unworn surfaces and no foreign matter adhering to prevent uneven fabric stress.
2. Clean Yarn Ends of Tangle and Contamination: Regularly clean the yarn ends on the stainless steel rollers at the bottom of the cylinder to prevent sudden changes in local resistance that could cause tension fluctuations.
3. Calibrate the Tension Detection Device: Regularly calibrate the tension sensor using standard weights to ensure detection accuracy and avoid miscontrol.
IV. Reasonable Setting of Process Parameters
1. Setting Tension Ranges According to Fabric Type
Lightweight silk and elastic knitted fabrics: 300–500N (low tension to prevent deformation)
Heavy cotton and polyester fabrics: 600–800N (high tension to prevent loosening and curling)
2. Controlling Operating Speed
It is recommended to control the linear speed at 15–20 meters/minute, especially for sensitive fabrics, to avoid high-speed amplification of fluctuations.
3. Maintaining Environmental Stability
Workshop temperature and humidity fluctuations should be controlled within a reasonable range to prevent tension changes caused by fabric moisture absorption or shrinkage.
V. Implementing Dynamic Monitoring and Preventive Maintenance
1. Real-time Monitoring of Tension Curves: View historical tension data through the inverter backend and intervene promptly upon detecting abnormal trends.
2. Establishing Inspection Logs: Regularly check bearing lubrication, transmission chain tension, and electrical wiring tightness to prevent problems before they occur.
3. Verification by trial dyeing of greige fabric: Conduct an empty dyeing test before formal production to observe the fabric condition and identify potential problems in advance.
