Causes and Preventive Measures of Aluminum Alloy Dimensional Accuracy and Shape Defects

Too thin: unreasonable adjustment of the reduction amount; poor control of the tolerance of the reduction indicator; improper adjustment of the micrometer; improper control of the roll shape

Excessive thickness: unreasonable adjustment of the reduction amount; poor control of the reduction indicator tolerance; improper adjustment of the micrometer; improper control of the roll shape

Too narrow: the distance between the disc shears is too narrow; when the hot-pressed disc shears are adjusted, the cold yield and the shear allowance during pre-shearing are not well considered

Too short: the automatic shearing control of the pre-shearing machine row is abnormal, the adjustment of the double-row shearing distance of the finishing machine row is too small, the cross-cutting machine row is out of control, and the cold shrinkage cannot be well considered when the thick plate machine row is cut to length.

The thickness of the aluminum cladding layer does not match: the reduction amount of the hot-rolled welding and pressing is too large, and the aluminum-clad plate is used incorrectly.

Unevenness (wave warpage): The plate stretches unevenly in the transverse direction during rolling; when the cold-rolled strip is coiled, when it is rolled into a drum shape, the uneven distribution of curling stress occurs in the transverse direction, causing uneven stretching; The uneven temperature distribution in the transverse direction of the strip will cause distortion, which will also affect the unevenness.

Edge wave: The edge stretches more than the center part during rolling; when the edge part of the strip becomes thicker, the aluminum coil becomes a drum shape, and the lateral edge part stretches during curling; change the initial crown of the roll, enhance cooling, and increase the roll deflection, Improves edge waves

Middle wave: the extension of the middle part is larger than that of the side part during rolling; the tower-shaped material appears in a drum shape when the coiling tension is large; changing the new crown of the roll, strengthening the cooling, and reducing the deflection of the roll can change the middle wave

Two-rib wave: Combination of roll deformation caused by rolling and improper roll thermal crown, caused by expansion from lateral edge to middle part; effective combination of roll initial crown to control the degree of cooling in different areas of the roll can be improved

Compound wave: The initial crown of the roll is too large, the thermal crown increases, and the middle wave quickly rises. If it is modified to reduce the roll bending, the edge wave is easy to appear; the cooling of the middle part of the roll can be strengthened, and the bending force of the roll can be changed, etc. Preventive measures Partial depression or partial blockage of the unilateral wave fuel injection pipe, local heating of the roller bulges and develops into local depression; adjust the fuel injection system to supply oil as required

Camber: Incorrect roll shape of the roll; misalignment of the strip during rolling; blockage of the emulsion nozzle, uneven cooling of the roll; different thicknesses on both sides of the incoming sheet; uneven deformation on both sides during rolling or calendering

Short cycle buckling: uneven lubrication and cooling; improper roll profile control

Longitudinal bending: The inner diameter of the plate reel is small, and the curling tension is large: the straightening conditions and processes are not suitable; the plate thickness deformation distribution is asymmetric, and the internal stress distribution is unbalanced and non-parallel

Lateral bending: the coiled shape of the plate is too “barrel-shaped”; when straightening with a tension roller straightener, the tension control between the rolls is not appropriate; the transverse thickness of the plate is deformed unevenly, asymmetrically, and the internal stress is not parallel

Distortion: Causes the same as unevenness

Middle arch: Uneven distribution of extension and thickness during rolling; improper control of roll initial crown, thermal crown, reduction ratio, tension, roll crown, etc.; rolling force causes roll distortion and flat deformation, roll roll during rolling The change of the gap along the lateral distribution of the plate is rolled with multiple passes and small reductions, which reduces the rolling load and can reduce the middle arch

Thinning of the end face: The lateral edge of the sheet is in a state of plane stress during rolling; the surface pressure of the roll becomes lower, and the flat deformation of the roll is caused by other reasons.

Wedge-shaped edge: the left and right sides of the rolling mill are not pressed down, and the transverse temperature difference of the plate is too large

Bell edge: Too many burrs on the edge of the board; the middle part of the board is thinner

Telescopic shape: the tension is too low during coiling; the rolling oil on the surface of the plate is excessive; the left and right pressing of the rolling mill is out of balance; the center of the plate is not positioned correctly