Four- and five-high rolling mills

Four rollers
The work roll has a smaller diameter and transmits the rolling torque, while the rolling pressure is borne by the backup roll with a larger diameter. The advantages of this kind of rolling mill are high relative rigidity, large reduction, small rolling force, and can roll thinner plates. There are two types of reversible and continuous rolling, which are widely used as medium and heavy plate rolling mills, plate and strip hot or cold rolling mills, and skin pass mills.
Five rollers
There are two types: one is the C-B-S (Contact-Bend-Straighten) rolling mill, which is a four-roll mill with a small diameter (1/20 of the work roll) idle roll that bends the rolled piece. The capacity is many times larger than that of a conventional four-high rolling mill. The rolled piece undergoes plastic bending deformation around the small idle roller, and can roll metal and alloy strips that are difficult to deform. The other is that the position of the middle small roller can be adjusted along the entrance or exit direction of the rolling mill to maintain the correct thickness of the rolled piece, and is used to roll stainless steel, carbon steel and non-ferrous metal strips with small thickness tolerances.
HC
High-performance rolling mill with controllable roll crown. It is equivalent to adding a pair of axially movable intermediate rollers between the work rolls and the back-up rollers of the four-high rolling mill, and adjusting the corresponding ends of the two intermediate roller bodies to positions corresponding to the two edges of the strip to improve The uniformity of pressure distribution and elastic flattening of the work roll ensures the dimensional accuracy of the strip and reduces defects such as ultra-thinness and cracking of its edges. HC rolling mill is suitable for cold rolling wide steel strips.
Partial eight roller
It is a variation of the four-high rolling mill. The diameter of the work roll is 1/6 of the backup roll, and is relatively offset to prevent the horizontal bending of the work roll. The rolling force is half that of the four-high rolling mill. The work roll has good stability and high horizontal stiffness, and can be used to roll some products that must be rolled by a twenty-high rolling mill. Its structure and adjustment are much simpler than the twenty-high rolling mill. This kind of rolling mill can be modified into two, four, eight and sixteen roller types, which is suitable for the needs of many varieties, so it is also called a multi-purpose rolling mill. It has two types: reversible and continuous rolling, and is used for cold rolling difficult-to-deform steel, silicon steel and non-ferrous metal strips.
six rollers
It consists of a pair of work rollers and two pairs of backup rollers, and has a relatively stable roller system. However, its rigidity is similar to that of a four-roll rolling mill and it is inconvenient to operate, so it is not widely used. It is generally used for rolling copper strips of high-precision submarine cables.
multi-roller
There are 3 types of twelve rollers, twenty rollers and thirty-six rollers. The pair of rolls with the smallest diameter in the middle of the rolling mill are the work rolls, and the rest are backup rolls. It has the advantages of relatively high stiffness, large reduction, small rolling force, and can roll extremely thin strips. The early multi-roll mill was driven by work rolls, and later it was driven by intermediate support rolls. It can roll foils with a width of 200 to 1000 mm and a thickness of 0.02 to 0.0015 mm.
Two large-diameter support rollers drive two sets of planetary roller systems. The slab or flat ingot can be hot-rolled into a thin strip in one pass, with a reduction rate of 90 to 95%. If the front process is equipped with a continuous casting machine and the back process is equipped with a tempering machine, the production process of hot-rolled strip steel can be simplified. The roll length of large planetary rolling mills can reach 1450 mm.