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During the slitting process on fully automatic high-speed slitting machines, if steel coils are wound in a slack state, internal layer slippage occurs within the coil. This can lead to various surface scratches on the steel plate, as well as repeated friction marks caused by scratched points.
In practice, even normally wound coils can develop scratches when wound beyond their normal tension during operation. Based on production experience, this primarily occurs in the following three scenarios:
First, scratches caused by improper uncoiler settings.
Key scenarios include: During operation of the fully automatic high-speed slitting machine, excessive counter-tension applied by the uncoiler exceeding the parent material's winding tension, insufficient braking force from the uncoiler, or inadequate pressure from the uncoiler's pressure rollers can all cause coil slackening, leading to scratches. Additionally, when a loosened coil enters the uncoiler, it may be re-tensioned during unwinding, causing scratches. If the uncoiler's counter-tension is excessively high, sudden re-tensioning of the loosened steel plate can also result in scratches. Therefore, measures should be taken to reduce braking force upon completion of operations.
Second, scratches caused by improper rewinder settings during coiling.
After a fully automatic high-speed slitting line stops and restarts, loose coils are prone to occur. Looseness in the outer ring during shearing, lateral misalignment of the coil during unwinding, and other factors can all cause scratches. Additionally, straight-pull shearing or re-winding a loose coil onto a mandrel can result in winding scratches.
The third scenario involves winding scratches caused by manual tensioners.
When a loose coil is wound under insufficient tension on the automatic high-speed slitter, using a manual tensioner to tighten it can cause misalignment during winding, resulting in scratches. Furthermore, lateral swaying or overlapping of the steel strip within the loop can also cause scratches.