Cold rolling mainly adopts the belt method production process, and a four-high reversible rolling mill or a four-high irreversible rolling mill is used for cold rolling. Currently, irreversible rolling mills are being developed for cold rolling. The rolling mill is equipped with hydraulic pressing, hydraulic roll bending, automatic thickness control system or thickness automatic control system for measuring roll gap and flatness controller. Various parameters are controlled, recorded and stored by micro-electronic computer to obtain accurate size and flatness. The tolerance of flat plate and strip, such as 0.18 mm strip, can reach ±5 micron. Small factories also produce plates using the block method. The cold deformation rate of aluminum after annealing can reach more than 90%. Multiphase duralumin alloys are significantly hardened by cold work and require intermediate annealing. The cold deformation rate after intermediate annealing is 60 to 70%. Hot rolling uses emulsion lubrication, and cold rolling has developed from emulsion to full oil lubrication.
A multi-stage cooling system with individually controlled nozzles is used to reduce the friction between the aluminum plate and the roll, cool the roll, control the roll shape, and wash away aluminum powder and other impurities to obtain good surface quality and plate shape. The coils after cold rolling and heat treatment are often finished on a roller straightening machine or on a stretch-bending continuous straightening machine train. Flattening and quenching the plate should be carried out during the aging incubation period, which is usually completed within 30 to 40 minutes after quenching. The total deformation of the quenched plate after straight calendering should not exceed 2%.