How Tension Frames Affect Strip Quality in Second-Hand Slitting Machines​

Tension frames (also known as tension 牌坊) are critical intermediate components in second-hand slitting machines, positioned between the unwinding unit and slitting knives. They maintain stable tension in metal strips during processing, directly influencing slit strip flatness and 收卷 (rewinding) quality.​

Tension Stability Control​

In second-hand slitting machines, tension frames use pneumatic or hydraulic cylinders to apply adjustable pressure (0.2-0.8 MPa) on pinch rolls, creating consistent tension (50-500 N/m depending on strip thickness). Stable tension prevents strip wrinkling (a common issue with thin strips ≤0.5mm) and ensures uniform knife engagement, reducing edge burr height to ≤0.05mm—meeting the requirements of electronic-grade copper strips (EN 1652:2020). For second-hand machines with fluctuating tension, upgrading to a load cell-based tension feedback system can reduce tension variation to ±3%, compared to ±8% with traditional mechanical controls.​

Strip Flatness Improvement​

Tension frames in well-maintained second-hand slitting machines work with leveling rollers to correct minor strip camber (≤1mm/m) before slitting. This is particularly important for high-strength steel strips (e.g., DP600) that retain residual stresses from previous processing. By adjusting the frame’s pinch roll pressure according to strip thickness (e.g., 0.3 MPa for 1mm strips, 0.6 MPa for 3mm strips), operators can reduce post-slitting strip warpage by 40-50%, eliminating the need for secondary leveling.​

Slitting Speed Optimization​

High-rigidity tension frames (constructed from cast iron HT300) in second-hand slitting machines withstand the dynamic forces of high-speed slitting (up to 600m/min for aluminum strips). Weak or deformed frames cause tension spikes, forcing operators to reduce speed by 20-25% to avoid strip breakage. Reinforcing frame joints with steel plates and replacing worn pinch roll bearings can restore the frame’s stability, allowing the machine to operate at rated speed and increasing throughput by 18-22%.​

Maintenance Best Practices​

To ensure reliable performance of tension frames in second-hand slitting machines:​

• Check cylinder air/hydraulic pressure daily; adjust to recommended values if deviations exceed 0.05 MPa.​

• Inspect pinch roll surface for indentations weekly; replace rolls if surface defects exceed 0.1mm in depth.​

• Clean tension sensor surfaces monthly to remove oil and dust, which can cause false tension readings.​

• Calibrate the tension control system quarterly using standard weights to verify accuracy.​

For second-hand slitting machines processing wide strips (≥1200mm), installing additional tension rolls in the frame can distribute tension more evenly, reducing edge-to-center tension differences by 30% and improving slitting consistency.​

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