Types of rolling mills



All-round rolling mills can be classified according to the arrangement and number of rolls, and can be classified according to the arrangement of racks.

two rolls

 Simple structure and wide range of uses. It is divided into reversible and irreversible. The former includes primary, rail beams, medium and thick plates, etc. The irreversible type includes billet continuous, stacked thin plate, thin plate or strip steel cooling, tempering machine, etc. In the early 1980s, the diameter of the second roll was 1500 mm, the length of the roll body was 3500 mm, and the rolling speed was 3-7 m/s.


Alternately rolled left or right from the upper and lower roll gaps, generally used as profile steel and rail beams. This has been replaced by high-efficiency two-rollers.

Lauter three-roller

The upper and lower rolls are driven, the center roll floats, and the rolled piece passes through the top or bottom of the middle roll. Due to the small diameter of the middle roll, the rolling force can be reduced. It is often used for rolling rail beams, section steel, medium and thick plates, and can also be used for billeting of small steel ingots. This rolling mill is gradually replaced by four rolls.

four rolls

The diameter of the work roll is small, and the rolling torque is transmitted, and the rolling pressure is accepted by the backup roll with a large diameter. The advantages of this type are relatively high rigidity, large reduction, small rolling force, and thinner plates can be rolled. There are two kinds of reversible and continuous rolling, widely used as medium and thick plate, strip hot rolling or cold rolling and tempering machine.

five rolls

There are two types: one is CBS (contact-bending-straightening), which is a four-roller with a small diameter (1/20 of the work roll) idler roll that bends the rolled piece, and its reduction ratio is The general four-roller is many times larger. The rolled piece undergoes plastic bending deformation around a small idle roll, and can roll difficult-to-deform metal and alloy strips. The other is that the position of the central small roll can be adjusted along the entrance or exit direction to maintain the correct thickness of the rolled piece, which is used to roll stainless steel, carbon steel and non-ferrous metal strips with small thickness tolerances.


High performance, controllable roll crown. It is equivalent to adding a pair of axially movable center rolls between the four-roll work rolls and backup rolls, and adjusting the corresponding ends of the two center roll bodies to the positions corresponding to the two edges of the strip to increase the pressure. The uniformity of the distribution and elastic flattening of the work rolls ensures the standard accuracy of the strip and reduces defects such as ultra-thinness and cracking at the edge. HC mills are suitable for cold rolling wide strips.

partial eight roll

It is a variant of the four-roller. The diameter of the work roll is 1/6 of that of the back-up roll, and the relative offset is made to prevent the horizontal bending of the work roll, and the rolling force is half that of the four rolls. The work roll has good stability and high horizontal rigidity, and can be used to roll some products that need to be rolled by 20 rolls. Its structure and its adjustment are much simpler than that of a twenty-high rolling mill. This type can be converted into two, four, eight, and sixteen roller types, which is suitable for various needs, so it is also called multi-purpose. It has two types of reversible and continuous rolling, and is used for cold rolling difficult-to-deform steel, silicon steel and non-ferrous metal strips.

six rolls

Consisting of a pair of work rolls and two pairs of support rolls, it has a relatively stable roll system. However, its rigidity is similar to that of four rolls, and its operation is inconvenient, so it is not widely used. It is generally used for rolling copper strips for high-precision submarine cables.


There are 3 types of 12-roll, 20-roll and 36-roll. A pair of rolls with the smallest diameter in the middle are work rolls, and the others are back-up rolls. It has the advantages of high relative rigidity, large reduction, small rolling force, and can roll extremely thin strips. The initial multi-roller was driven by the work roll, and later by the center support roll. It can roll foils with a width of 200-1000 mm and a thickness of 0.02-0.0015 mm.


Two large-diameter back-up rolls drive two sets of planetary roll systems, and the slab or slab can be hot-rolled into thin strips in one pass, with a reduction rate of 90-95%. If the continuous casting machine is used in the previous process and the tempering machine is used in the subsequent process, the production process of hot-rolled strip can be simplified. Large planetary mills have roll body lengths up to 1450 mm.


It consists of a pair of horizontal rolls and vertical rolls, and all rolls are driven by power. For rolling slabs or flat bars.

Almighty Steel Beam

The structure is similar to the universal rolling mill, only the axes of the vertical roll and the horizontal roll are placed in the same vertical plane, and the vertical roll is driven. It is suitable for rolling wide-rim steel beams with a rolling height of 300-1200 mm.

Disc piercer

The axis of the rolled piece is lower than the axis of the disc. When the disc rotates, the rolled piece will travel against the mandrel in a spiral, and the solid round steel will be rolled into a hollow blank tube. It is suitable for rolling 60-150 seamless steel pipes. There is also a cross-rolling piercer, whose drum-shaped rolls are skewed and rotated. The working principle is similar to that of a disc piercer, and is suitable for rolling 60-650 seamless steel pipes. The cross-rolling piercing machine is matched with the automatic pipe rolling mill, leveling, sizing (reducing) machine and skew-roll straightening machine in Figure 7 to form a seamless steel pipe thermal group.


The inner and outer circles of the tire are rolled by a pair of opposite rollers, and the two ends of the tire are rolled by a pair of inclined tapered rollers. Inner and outer rings for rolled wheels or rolling bearings.

The ball has a roll with a spiral semi-circular groove, and the bar is rolled into a ball by spiraling between the rotating rolls, and the ball with a diameter of 60-650 mm can be rolled.