The Impact of Work Roll Bending Devices on Second-Hand Cold Rolling Mills​

Work roll bending devices are key precision components in second-hand cold rolling mills, designed to adjust the curvature of work rolls. They play a critical role in correcting strip shape defects and ensuring uniform thickness across the strip width, especially for high-precision applications like automotive body panels.​

Strip Shape Correction​

In second-hand cold rolling mills, work roll bending devices apply hydraulic force (10-50 kN) to the ends or middle of work rolls, modifying the roll profile to counteract shape defects such as edge waves (caused by excessive rolling at strip edges) or center buckles (from over-rolling at the center). For example, applying 25 kN of positive bending force (pushing rolls outward) can reduce edge wave height from 5mm/m to ≤1mm/m for 1.2mm-thick cold-rolled steel strips (DC04 grade). This correction meets the strict shape tolerance requirements of automotive manufacturers (ISO 16160:2017), reducing rework rates by 35-40%.​

Thickness Uniformity Enhancement​

By adjusting the work roll profile, bending devices in second-hand cold rolling mills ensure consistent contact pressure between rolls and the strip. This reduces transverse thickness variation (TTV) from ±5% to ±1.5% for thin strips (0.1mm-0.5mm), critical for electronic components like lithium-ion battery casings. For second-hand mills with aging bending systems, replacing manual valves with proportional hydraulic valves can improve force control accuracy to ±2%, further reducing TTV by 10-15%.​

Roll Life Extension​

Proper use of work roll bending devices minimizes uneven roll wear. In second-hand cold rolling mills, uneven wear can reduce work roll life by 20-25% and cause periodic thickness variations in the strip. By alternating positive and negative bending forces during production runs (e.g., 15 kN positive for 2 hours, then 10 kN negative for 2 hours), operators can distribute wear evenly across the roll surface, extending roll life from 800 tons to 1000 tons per set.​

Maintenance and Calibration Tips​

To maintain the performance of work roll bending devices in second-hand cold rolling mills:​

• Check hydraulic oil cleanliness weekly; ensure particle count is ≤16/13 (ISO 4406) to prevent valve clogging.​

• Inspect bending cylinder seals monthly for leaks; replace seals if oil consumption exceeds 0.5L/day.​

• Calibrate the force sensor quarterly using a hydraulic test bench to verify force accuracy.​

• Measure work roll profile monthly using a roll contour measuring instrument; adjust bending parameters if profile deviation exceeds 0.02mm.​

Upgrading the bending device’s control system to a digital PLC-based system allows real-time adjustment of bending force based on strip shape feedback, improving shape correction efficiency by 25% compared to analog systems.​

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