Since the invention of the multi-high mill in the early 20th century, various multi-high mills have been greatly developed.More than 95% of the world’s stainless steel strips and hard-to-deform metal strips are produced by multi-roll mills.The characteristics, application and development history of multi-high rolling mill are mainly introduced.Century-old events of multi-roll mill;Various types of tower roll system and compound multi-high rolling mill;The Rohn type, Sendzimir type, Frohling type multi-high mill, CR mill, Demag and DMS 20 h double arch mill, Mitsubishi and Hitachi HZ20 h double arch mill, HDK 10 h mill, MKW are introduced emphaticallyRolling mill, Z-HI 18-h rolling mill, and sr12/20 h interchangeable multi-high mill and integrated multi-high mill designed and developed by The Chinese.
Title：Features of multi – high rolling mill
Keyword：Rolling mill, features,introduction
Related Product：Rolling mill rolls
Cold-rolled strips were originally rolled on 2-h and 4-h mills. With the development of science and industry technology, thinner, wider and finer strips are needed, and the 4-h mill can not meet this requirement. Because the work roll diameter of a 4-h mill is larger, the elastic deformation of the roll itself during rolling is larger than the thickness of the strip to be rolled. The elastic deformation of the roll is proportional to the diameter of the roll at the same unit pressure. When the roller material is constant, to reduce the elastic deformation value of the roller, it is necessary to reduce the diameter of the roller, and the reduction of the diameter of the roller will reduce the stiffness of the roller system. In order to solve this contradiction, a new type of rolling mill with small roll diameter and large rigidity tower supporting roll system appeared — multi-high rolling mill.
Compared with 4 and 6 h rolling mills, multi-high rolling mills have the following advantages:
(1) The stiffness of the roller system is large due to the multi-point support of the back lining bearing roller structure.The vertical and horizontal deflection of the roll is reduced, allowing the use of a small diameter work roll;
(2) Due to the use of small diameter of the work roller, reduce the rolling pressure, and the roller stiffness is large.Therefore, a more ideal thickness tolerance can be obtained by using AGC.
(3) Small diameter work roller can get a large pass down rate (up to 60%) and rolling process compression rate (up to 90%), without intermediate annealing to achieve the desired product thickness, so as to achieve the purpose of saving energy and reducing product cost;
(4) the use of small diameter work roller, you can get larger width ratio of products.Generally, the minimum rolling thickness of a rolling mill is 1/1000 ~ 1/2000 of the diameter of the work roll.
(5) It is convenient and fast to change the work roll (only 1-2 minutes), which improves the production efficiency;
(6) The use of hard alloy work roller becomes a reality;
(7) Small rollers do not need special large roller grinding machine, but only general cylindrical grinding machine, can meet the production requirements;
(8) With special roll shape adjustment mechanism, so that the roll shape can be adjusted and controlled in the rolling process.In order to ensure the thickness accuracy, flatness and surface quality of strip, automatic control of strip shape can be achieved.
(9) Because of the high stiffness of the roll system, the multi-high mill can obtain high strip thickness accuracy even without thickness control;
(10) The use of small diameter work roller reduces the stress in the deformation zone and the width decreases, thus reducing the strip crack edge;
(11) Expanded rolled strip specifications.The ratio of blank to finished product thickness is more than 50, and the ratio of maximum width to minimum width is 2∶ 1.
(12) When rolling refractory metals and alloys, compared with 4 and 6 h rolling mills, energy consumption can be reduced (some experts hold negative opinions on this);
(13) The weight of rolling mill is less than that of 4-h and 6-H rolling mills, thus reducing the construction cost of rolling mill and workshop;
(14) The cost of rolled strip is low, about 40% of the 4-h mill.Cold rolled sheet and strip of high strength steel and precision alloy produced by multi-high mill occupies a special position in the field of sheet metal production.Multi-roll mills almost monopolized the stainless steel strip product market, multi-roll mills are also used to produce most oriented silicon steel strip and corrosion resistant steel strip.Multi – high mills account for more than 10% of cold strip mills worldwide.Only senjimil type multi – high mill has more than 500 units in the world operation.