How to Improve Slightly Loose Copper Wire Strands?
How to improve slightly loose copper wire strands without adjusting lay length?
When the lay length cannot be adjusted, the key to improving loose copper wire strands lies in optimizing process parameters, equipment conditions, and material treatment. Specific measures are as follows:
Precision Tension Control
Segmented Tension Adjustment:
Unwinding Tension: Ensure stable unwinding tension.
Stranding Tension: Add tension compensation devices near the stranding point to prevent copper wire slackness due to inertia.
Rewinding Tension: Maintain slightly higher tension during rewinding (higher than unwinding tension) to prevent post-stranding loosening.
Tension Sensor Calibration: Regularly check tensioner accuracy to avoid tension fluctuations caused by equipment errors.
Lubrication Optimization (Copper-Specific)
Lubricant Selection:
Use water-soluble lubricants designed for copper wires (e.g., fatty acid amides) to reduce friction while ensuring easy cleaning and minimal residue that could affect conductivity.
Control lubricant coating to form a uniform film on the copper surface (approx. 0.2–0.5 μm thickness).
Lubrication Method Improvement: Adopt felt impregnation or spray lubrication to avoid excessive lubrication-induced slippage.
Critical Equipment Component Maintenance
Mold and Guide Wheel Inspection:
Replace worn stranding molds (recommended aperture: 5%–8% smaller than the bundle’s outer diameter to ensure compression force).
Use ceramic or chrome-plated guide wheels to minimize surface scratches on copper wires.
Stranding Machine Concentricity Calibration: Regularly inspect spindle concentricity (deviation ≤0.02 mm) to prevent uneven stranding due to eccentricity.
Copper Wire Pretreatment
Annealing Process Optimization:
If copper wires are too hard, restore ductility through annealing (200–300°C), but control post-annealing tensile strength (e.g., soft-state copper ≤250 MPa).
Cool promptly after annealing to avoid excessive oxide layer formation.
Surface Cleaning: Use acid washing (5%–10% dilute sulfuric acid) or ultrasonic cleaning to remove oxides and enhance stranding adhesion.
Process Parameter Fine-Tuning
Stranding Speed Matching:
Control copper wire stranding speed at 20–50 m/min (depending on wire diameter); increase tension synchronously at high speeds.
Pre-Twist Device: Add a pre-twist mechanism (pre-twist angle: 3°–5°) before stranding to improve compactness.
Environmental Control: Maintain workshop temperature at 20–25°C and humidity at 40%–60% to prevent thermal expansion/contraction or accelerated oxidation.
Quality Inspection & Feedback
Online Monitoring System:
Install real-time tension/diameter monitors with threshold alarms (e.g., ±10% tension fluctuation triggers shutdown).
Use laser diameter gauges to detect strand outer diameter; automatically adjust processes if deviations exceed ±0.03 mm.
Destructive Sampling:
Regularly cut samples for cross-sectional analysis, requiring wire gaps ≤5% of wire diameter.
Troubleshooting Flowchart
1. Unstable tension → Check tension device/calibrate sensor;
2. Worn mold → Replace stranding mold (reduce aperture by 5%);
3. Insufficient lubrication → Increase lubricant coating or switch type;
4. High copper hardness → Optimize annealing (250°C × 2h);
5. Environmental interference → Control temperature/humidity or add anti-oxidation coating.
By implementing these comprehensive measures, the compactness of copper wire stranding can be significantly improved without adjusting the lay length, while avoiding wire breaks or surface damage.
