Due to different treatment methods in the coating process, the surface conditions of cold-rolled coils are also different, such as ordinary galvanized zinc coils, refined zinc coils, flat zinc coils, zinc-free coils, surface phosphating, etc. Cold-rolled coils should have good appearance and should not have defects such as coating, holes, cracks and scum, excessive coating thickness, scratches, chromic acid stain, white rust and other defects that are harmful to the use of the product.
Cold rolling is the core process of cold rolling production. First, the pretreated raw materials are fed into the cold rolling mill. Through the action of the roller table and rolling, the raw materials are gradually narrowed and thinned, and the required plate shape is formed. During the cold rolling process, the spacing of the roller tables and the rolling intensity need to be adjusted according to product requirements to control the size and performance of the product.
Cold-rolled products also require a series of post-processing processes. The first is annealing treatment, which restores the product to a softened state by heating and cooling it to improve the mechanical properties and processing performance of the product. Then cutting, trimming and sizing are carried out to obtain the final product that meets the requirements. Finally, surface treatments such as rust removal and spray painting are carried out on the product to improve the appearance quality and corrosion resistance of the product.
The reason why cold-rolled coils are coated with a layer of zinc on the surface of steel is because steel is easily oxidized by oxides such as water in the air and corroded. Galvanizing is actually to better protect the steel. Cold rolled coils have two major advantages, one is adhesion and the other is weldability. It is precisely because of these two advantages that it has been widely used in construction, industry, automotive industry, commerce and other fields. Another important feature is corrosion resistance, which can play a good role in the manufacturing of home appliance casings.
