Traditional flatness control methods include roll tilt, work roll bending and adjustment roll cooling system, but these methods can not fully meet the requirements of flatness control. Although the bending equipment responds, the rolling force and rolling torque workpiece width outside the harmful interference make a considerable part of the bending force offset, hindering the development of the bending roll; In order to improve the resolution accuracy of coolant flow, the flow ratio of the nozzle is increased to 10:1. In addition, aluminum plate manufacturers use various mechanical methods to modify the roll system to achieve the purpose of rapid roll change:
(1) HC (high camber) six roll mill - a pair of intermediate rolls can be added between the work roll and the back-up roll of the four roll mill to move relatively along the axial direction. The defined moving distance of the strip width is used to eliminate the relationship between the harmful strip width work roll and the back-up roll, reduce the dilution of the strip on both sides, and improve the influence of the roll bending force control panel shape.
(2) VC (variable radian) roll adopts the back-up roll in the hydraulic cavity. By changing the cavity pressure, the radian of the back-up roll is adjusted to counteract the magic of deflection caused by the roll rolling force.
(3) TP (conical piston) roller both ends support the conical piston ring in the roller, and the adjustment arc magic of the piston and the hydraulic drive roller ring.
(4) DSR (dynamic camber) roll 7 hydraulic cylinder liner is on the back-up roll, which uses the hydraulic rotating shaft sleeve to directly adjust the roll camber (5) at the position required by the flatness of the rolled piece. CVC roll (continuous variable camber) uses two working rolls whose shape is like a bowling ball. The two rolls are of the same grinding degree, but they are arranged up and down in dislocation 18, When the actual diameter difference of the roll length is less than 1mm, when the gap shape of the roll moves relatively, according to the law of linear continuous change position, when the working roll moves axially between 150 mm, the radian of each roll can be 0. 5mm to + 0mm. 3 m3) the movement of the intermediate roll system and CVC working roll of the zero resistance HC mill takes several seconds, so it is usually preset to adjust the no-load operation of the mill, instead of rolling a VC roll, TP roll, safety zone roll and preset adjustment under dynamic load. It can also be applied to the use of dynamic long VC roll and TP roll, and the rolling force also acts on the supporting roll at the neck. When the DSR roll is used, the hydraulic cylinder in the supporting roll replaces the pressing device at the roll neck.
Therefore, the platform deviation of hot rolled strip can be changed without affecting the roll deflection, which is the main reason for the thickness deviation of the final product. The advanced equipment and control system adopted in the cold rolling mill can be less than a thousandth of the vertical thickness tolerance, but the horizontal thickness tolerance is usually greater than the skip close. This is due to the cold rolling of strip steel, because the thickness is very small and the horizontal flow of metal is limited, so the original crown is improved, and the thickness of aluminum alloy strip is greater than 12mm when the straightness deviation does not occur, It can be corrected without affecting the crown of the rolled piece. Since the thickness of the finishing mill of the hot rolling finishing mill is less than the minimum thickness, it is necessary to use the flatness meter to monitor the flatness of the product in addition to using the profilometer to detect the convexity of the product when coiling on the finishing mill for the last time after hot rolling. The strip rolled from the hot rolling mill should have a slight intermediate crown, but not an intermediate crown, because the central part of the strip can accommodate more stress than the edge, but still maintain its flatness.
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