What are the main causes of roll cracks?
A: Most commonly caused by excessive local pressure and rapid heating/cooling of the roll. For example, clogged emulsion nozzles in the mill can worsen local cooling conditions for the roll; low winter temperatures and drastic temperature changes in the roll make it more prone to cracking than in summer.
What are the consequences and related causes of roll peeling?
A: The consequences range from minor issues where the roll can be reused after regrinding to severe issues requiring immediate scrapping. It is a follow-up problem to untreated roll cracks; continued cracking leads to blocky or flaky peeling.
How does the roll sticking defect form during cold rolling?
A: The main causes include excessive local reduction, broken edges in the strip, strip overlap, and strip edge damage. These conditions can cause excessive local adhesion and sticking between the strip and the roll.
What causes the roll sticking defect in cold-rolled coils?
A: Excessive reduction can cause the strip to develop heavy layers or slight folds, or the strip may deviate from its designated path, resulting in heavy layers and ultimately causing roll defects. In minor cases, marks will be left on both the strip and the roll.
What factors typically cause roll breakage accidents?
A: Support roll breakage is often caused by a combination of factors, including excessive reduction (excessive rolling force), defects such as non-metallic inclusions and bubbles inside the roll, and temperature stress generated during operation.