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Common quality defects and causes of aluminum coil

Date: 2019-05-17 11:30
Common quality defects and causes of aluminum coil
 
First, non-metal pressing
 
Definition: Non-metallic debris is pressed into the plate and belt surface. The surface has obvious dot-like or long strips of yellow-black defects.
 
The main reason: the equipment conditions in the rolling process are not clean; the rolling process lubricant is not quiet; the process lubricant injection pressure is insufficient; the surface of the slab is scratched.
 
Second, the bruise
 
Definition: A bundle (or group) distribution of scratches on the surface of the board or belt due to the relative sliding or dislocation of the edge or surface between the objects or the surface.
 
The main reason: when the plates and belts are in contact with the guides and equipment during the processing and production, the relative friction causes scratches; the end faces of the cold rolled coils are not aligned, and the displacement, layer and layer are generated when the vertical furnace is annealed and inverted. There is a scratch between the two; the tension is improper during cold rolling, and the interlayer is displaced during the unwinding to cause scratches; the improper inspection or packaging operation causes the sliding between the plates to cause scratches.
 
Third, bruises
 
Definition: Scratches on the surface of the plate, belt or end surface after the aluminum plate and aluminum coil collide with other objects, and most of the metal is extruded at the margin of the depression.
 
The main reason: the board and the coil collide with other objects during the handling or storage process; the board and the coil are generated by the collision of other protrusions on the annealing rack or the chassis.
 
Fourth, the edge
 
Definition: After rolling or shearing, the edges of the strip are lifted.
 
The main reason: excessive reduction during rolling; uneven distribution of lubricating oil during rolling; improper adjustment of cutting edges during shearing.
 
Five, broken
 
Definition: Deformation creases produced after the sheet is bent.
 
The main reason: the feeding of the multi-roll straightening machine is not correct; the sheet is unbalanced during the turning or handling; the force is unbalanced when the upper sheet is loaded.
 
Six, collapse
 
Definition: The core is severely deformed and the roll is not round.
 
The main reason: improper tension in the aluminum coil during crimping; external force compression; low core strength; no core roll is annealed.
 
Seven, the wrong layer
 
Definition: Irregularly displaced between the end face of the strip and the layer, resulting in uneven end faces.
 
The main reason is that the blank is not flat; the rolling mill unwinding and the winding tension are improperly controlled; the pressing amount is uneven, the sleeve is strung; the flattening roller is improperly adjusted; during the winding process, the centering system is abnormal; the roller system is not parallel.
 
Eight, tower shape
 
Definition: The belt layer and the layer are swayed to one side to form a tower-like offset.
 
The main reason: the shape of the incoming plate is not good, the tension control is improper; the adjustment control system of the take-up centering is abnormal; the leader is not firmly bonded during winding.
 
Nine, loose rolls
 
Definition: When the coiling and unwinding, the layer and the layer are loosened, and when it is serious, the whole volume is affected.
 
The main reason: the tension is uneven or too small during the coiling process; the pressure of the pressure roller is too small when the coil is unwound; the steel strip or the clamp is not firm and is generated during lifting.
 
Ten, bird's nest
 
Definition: A local "V" type defect is produced on the end face of the tape. This defect is generated during or after the coil take-up process, and some are generated after a certain period of time.
 
The main reason is that the tension before and after the coil winding process is improperly used; the expansion ring is not round or the bottom is not round when coiled, and the unbalanced stress is generated after the unwinding; the core quality is poor.
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