As the core equipment in the field of metal processing, rolling mill exerts pressure on metal billet to make it plastic deformation, which is widely used in steel, non-ferrous metals, automobile manufacturing and other industries. In this paper, the classification system and technical characteristics of rolling mill are systematically introduced to provide reference for industrial practitioners in equipment selection.
First, according to roll configuration classification
Two high rolling mill
The basic rolling mill adopts two rolls arranged parallel up and down, and the reduction is controlled by adjusting the roll gap. It is typically used in billet rolling and rough processing of medium and thick plates, such as preliminary forming of billets. Its structure is simple but its precision is limited, and it is gradually replaced by multi-roll models.
Four high rolling mill
It consists of two work rolls and two support rolls, which enhance the rigidity of the system. After the diameter of the work roll is reduced, the rolling precision is significantly improved, and the thickness tolerance of cold rolling sheet can reach ±0.005mm. Widely used in automotive plate, tinplate and other precision strip production.
Six high rolling mill
Intermediate rollers are added on the basis of four rollers to form the technical basis of CVC (continuously variable crown). The shape of the roll gap can be dynamically adjusted by moving the intermediate roll axially, which is especially suitable for ultra-thin stainless steel (less than 0.1mm) rolling. In 2022, the six-roll cold rolling unit introduced by a domestic steel mill successfully achieved mass production of copper foil for new energy battery pole sheets.
Second, according to the processing temperature classification
Hot rolling mill
The working temperature is above the recrystallization temperature (steel parts are usually >1100℃), equipped with high pressure water descaling system. Typical production lines include roughing mill units and finishing mill units, which can produce 5-150mm thick steel plates for building structures, shipbuilding and other fields.
Cold rolling mill
Rolling at room temperature can improve the strength and surface quality of materials, and it is necessary to configure high stiffness frame and rolling oil circulation system. The speed of modern tandem cold rolling mill can reach 1500m/min, and the products are used in high-end fields such as household appliance panels and precision instrument components.
3. Classification by product form
Strip mill
Including furnace rolling mill, planetary rolling mill and other special models. The 2250mm hot continuous rolling mill, which will be put into operation in 2023, adopts hydraulic AGC automatic thickness control, with an annual output of 3 million tons of automotive plates.
Section mill
H-shaped steel mill adopts universal rolling technology, and the horizontal roll and vertical roll cooperate to form. The section steel continuous rolling unit developed by a domestic heavy machinery enterprise can realize the continuous production of complex section profiles, and the products are applied to the construction of high-speed railway tracks.
Tube mill
The limited movement mandrel continuous rolling pipe unit (MPM) adopts multi-stand tandem arrangement and dynamic control of mandrel speed, which can produce oil casing with diameter of 219-426mm and wall thickness accuracy of ±5%.
