I. Core Cause Analysis
1. Outdated Control System
Traditional single-frequency converters or DC motor controls have slow response and lack real-time feedback, making it difficult to cope with tension fluctuations caused by changes in roll diameter.
2. Insufficient Drive Performance
Ordinary frequency converters have inaccurate torque control at low speeds (e.g., 1–3Hz), resulting in unstable low-tension output.
3. Poor Mechanical Condition
Mechanical problems such as non-parallel guide rollers, bearing wear, and yarn knots directly interfere with tension transmission.
4. Mismatched Process Parameters
Tension settings that are too high or too low, excessively high operating speeds, and large fluctuations in temperature and humidity all affect the stress state of the fabric.
II. Solutions and Practical Suggestions
1. Upgrade to a Closed-Loop Tension Control System
Adopting a closed-loop solution of a high-performance vector frequency converter + tension sensor + PLC achieves millisecond-level response adjustment, ensuring steady-state tension fluctuations are controlled within ±5%.
It is recommended to use dedicated tension control frequency converters such as the Huichuan MD330, which supports automatic roll diameter calculation and taper compensation.
2. Optimize Variable Frequency Control Mode
Use speed mode on the winding side and torque mode on the unwinding side. The roles are automatically switched after the fabric roll reaches its end.
Enable the "pre-drive" function to dynamically match the angular velocity based on the linear speed and roll diameter, achieving constant linear speed operation.
3. Enhance Mechanical Maintenance and Calibration
Regularly check the parallelism of the rollers; deviation ≤ 0.5mm/m.
Clean the yarn ends and knots on the stainless steel rollers at the bottom of the cylinder, keeping the roller surface clean and smooth.
Calibrate the tension detection roller to avoid lateral force or contamination affecting signal accuracy.
4. Set Process Parameters Appropriately
Adjust tension according to fabric type: use low tension (300–500N) for lightweight or elastic fabrics, and appropriately increase it for heavy fabrics.
Control the operating speed, especially for knitted fabrics, it is recommended to control it at 15–20 meters/minute to reduce vibration.
Maintain stable temperature and humidity in the workshop to prevent fabric shrinkage and deformation due to environmental changes.
5. Implement Regular Calibration and Monitoring
Regularly calibrate the tension sensor using standard weights to ensure accurate detection.
Monitor the tension curve in real time through the inverter's backend and intervene promptly if any abnormalities are detected.
