1. Non metallic press in
Main reasons: the equipment conditions of the rolling process are not clean; rolling process lubricant is not quiet; insufficient injection pressure of process lubricant; there are scratches on the slab surface.
Main causes: when the plate and belt are in contact with the guide and equipment during processing and production, they produce relative friction and cause scratch; the end face of cold rolled coil is not aligned, resulting in dislocation and scratch between layers during annealing turnover in vertical furnace; improper tension during cold rolling and scratch caused by interlaminar dislocation during uncoiling; scratches caused by sliding between plates due to improper finishing acceptance or packaging operation.
Main causes: the plate and coil collide with other objects during handling or storage; the plate and coil are caused by the collision of other protrusions on the annealing rack or chassis.
4. Edge warping
Main reasons: excessive reduction during rolling; uneven distribution of lubricating oil during rolling; improper adjustment of cutting edge during cutting.
Main reasons: incorrect feeding during feeding of multi roll straightener; the stress of a thin plate is unbalanced during turning or handling; when stacking the sheets, the force is unbalanced.
6. Collapse roll
Main reasons: improper tension during crimping; external pressure; low core strength; coreless coil is produced by annealing.
7. Staggered layer
Main reasons: the blank is not flat; improper control of uncoiling and coiling tension of rolling mill; the reduction is uneven and the sleeve moves in series; improper adjustment of flattening roller; during coiling, the centering system is abnormal; poor parallelism of the roll system.
8. Tower shape
Main reasons: bad shape of incoming sheet and improper tension control; the coiling alignment control system is abnormal. The head is not firmly bonded during coiling.
9. Loose roll
Main causes: uneven or too small tension during coiling; the pressure of the pressing roller is too small when uncoiling; the steel belt or clip is not firm, which occurs during hoisting.
10. Bird's nest
Main reasons: improper use of front and rear tension during tape coiling; the expansion ring is not round or the backing is not round during coiling, which is caused by the uneven distribution of stress after coiling; poor core quality.