Common failure forms and causes of rolls

1, cracks.
Roll cracks are mainly caused by excessive local pressure on the rolls and the rolls are cooled and heated sharply. Rolling mill, if the emulsion nozzle blockage, resulting in roll local cooling conditions are not good, it will produce cracks. Winter due to lower temperatures, so it is easier to produce cracks than in summer.


2, falling skin.
Cracks continue to develop on the formation of block or sheet peeling, peeling light can be regrinded to continue to use, peeling serious rolls are scrapped.
3, pitting.
Pitting is mainly due to the strip weld or other debris into the mill, so that the roll surface was scratched out of different shapes of the pit. Generally pitted rolls must be replaced. Strip weld quality is not good, rolling operation to the weld should be lifted and pressed to prevent pitting.
4, sticky roll.
Sticky roll is due to the cold rolling process, broken fragments, wave folding and broken edges appear, and due to high pressure instantaneous high temperature, it is very easy to form a steel strip and roll bonding, resulting in small area of damage to the roll. Through grinding, roll surface cracks can continue to use after elimination, but its service life is significantly reduced, and in the future use of easy to peel off the accident.


5, le roll.
Le roll is mainly caused by too much pressure down the strip to produce heavy skin or slight folding and strip run-off to produce heavy skin. Le roll serious, sticky roll, the strip was rolled crack. Le roll slight, strip and rolls have le marks.
6, broken rollers.
Roll breakage is mainly due to overpressure (i.e., rolling pressure is too large), roll internal defects (non-metallic inclusions, bubbles, etc.) and roll temperature is not uniform to produce a stress field and so on.

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