The Characteristics of Cold Rolling Production Process

The so-called cold rolling production of forged steel is not simply "cold rolling". Annealing, pickling, grinding, etc. are required before cold rolling, and flattening, straightening, shearing, and stacking are required after cold rolling, so it is actually the whole process from the hot-rolled coil to the production of the cold-rolled product. .

　　 Due to the characteristics of forged steel cold rolling and the special requirements for product quality, the cold rolling production process has the following characteristics:

　　① Cold rolled forged steel is a kind of high-alloy steel, which has greater resistance to rolling deformation. In order to carry out high-efficiency and high-precision rolling, a rigid rolling mill should be used, and a multi-roll cold rolling mill is generally used.

　　②When strip steel is cold rolled on a reversing mill, the head and tail parts wound on the coiler cannot be pressed down, and are cut off and become waste products. In order to change this situation and increase the yield rate, both ends of the strip steel must be welded and leaded before rolling; in addition, if the weight of the hot rolled coil is too small, in order to improve the rolling efficiency and yield rate, the steel coil needs to be combined and welded in advance. ; On the continuous annealing and pickling line, because it is a continuous operation, the steel strip head and tail connections also need to be welded. Therefore, welding is an indispensable link in the production of forged steel cold rolling. However, the welding of forged steel cold-rolled steel is different from ordinary steel, and it is much more difficult to weld than ordinary steel; in particular, some welds need to be pressed down, and the requirements for welding quality are much stricter. Therefore, the special welding process is also a feature of forged steel cold-rolled cold-rolled strip production.

　　③In the process of cold rolling of forged steel, the raw material (hot rolled coil) needs to be annealed, during the cold rolling process, intermediate annealing is needed, and the final product needs to be annealed, so annealing is an important part of the production. However, there are many types of forged steel cold-rolled, and the properties of various steels are different. The purpose, method and requirements of heat treatment are different from the general, and there is a unique process system.

　　④ Cold-rolled forged steel is a high-grade steel product. It has very strict requirements on the surface quality. Not only does it not allow the metallurgical defects caused by the previous process, but also the obvious defects caused by the cold-rolling process. For this reason, a series of elimination and protection measures have been taken in the production process. For example: in order to eliminate the oxide scale of hot rolling, hot-rolled strip steel should be shot peened and pickled; in order to eliminate the defects caused by the blank and the defects caused by cold rolling and heat treatment, the strip steel is often grinded on the grinding unit ; In order to ensure the surface quality after cold rolling, there are very strict requirements on the grinding of the rolls; in order to prevent scratches during the production process, the steel coils of each unit are required to be tightly coiled, and many units before and after cold rolling are coiled In addition, some special protective measures have been taken on the operations and equipment that are prone to scratches; in order to obtain a good and uniform surface gloss, the finished product should be sour after annealing. For washing, the bright panels with special requirements must be annealed in protective atmosphere; in order to protect the surface of the finished product, the surface of some products must be covered with a film and so on. In short, the production of forged steel cold rolling is a meticulous process, which is unmatched by other steel grades.

     ⑤The finishing of forged steel cold rolling is also different from ordinary steel. It has some special requirements. For example, the flattening process must not only improve the shape of the plate, but also use rolls with high smoothness (except for hemp panels) to produce smooth 2B steel plates. Ferritic steel also needs to control the flat reduction (or elongation) to improve the forming performance of the steel plate, which is actually a quenched and tempered rolling. Forged steel cold-rolled steel is harder and has strict requirements on flatness, so it must be straightened with a powerful straightening machine, and products with different thicknesses often require different straightening methods. Forged steel cold-rolled cold-rolled products are usually delivered in two ways, coils and cut plates, and some need to be delivered in strips. Therefore, the modern forged steel cold-rolling and cold-rolling plant should be equipped with slitting and cross-cutting units respectively.

　　⑥ The production of cold-rolled stainless steel is a multi-unit joint operation. Process balance and process management are very important. A strong production scheduling system must be in place to ensure continuous high-quality production. In addition, the equipment of the cold-rolled stainless steel plant is relatively complicated. There are many units, high-quality, sophisticated, and sophisticated equipment, involving various aspects of technology such as machinery, electricity, instrument automation, and thermal engineering. Good equipment management is to improve the production level and The fundamental guarantee of product quality.