Roll Introduction to Development

　　The main working parts and tools used for the continuous plastic deformation of metal on rolling mills. Rolls are mainly composed of three parts: roll body, roll neck, and shaft head. The roll body is the middle part of the roll, which is actually involved in rolling metal. It has a smooth cylindrical or grooved surface. The roller neck is installed in the bearing, and the roll force is transmitted to the frame through the bearing seat and clamping device. The drive end shaft head is connected to the gear seat through a connecting shaft, transmitting the rotating torque of the motor to the roll. Rolls can be arranged in the form of two rolls, three rolls, four rolls, or multiple rolls in the rolling mill frame.

　　With the development of metallurgical technology and rolling equipment, the varieties and manufacturing processes of rolls are also constantly developing. In the Middle Ages, low-strength gray cast iron rolls were used to roll soft non-ferrous metals. In the mid-18th century, Britain mastered the technology of producing cold cast iron rolls, which were used to roll steel plates. The progress of European steelmaking technology in the second half of the 19th century required the rolling of larger ingots, and neither gray cast iron rolls nor cold-hardened cast iron Roll could meet the requirements in terms of strength. This led to the birth of ordinary cast steel rolls with a carbon content of 0.4% ~ 0.6%. The emergence of large forging equipment further improved the strength and toughness of forged rolls of this composition. At the beginning of the 20th century, the use of alloying elements and the introduction of heat treatment significantly improved the wear resistance, strength, and toughness of cast steel and forged steel cold and hot rolling rolls. The addition of molybdenum to cast iron rolls improved the surface quality of hot-rolled strip steel. Through flushing and composite casting, the strength of the cast roll core was significantly improved.

　　 Roll The large-scale use of alloying elements began after World War II. This was the result of the development of rolling equipment towards large-scale, continuous, high-speed, and automated operations, as well as the result of higher requirements for roll performance after the improvement of rolling strength and deformation resistance. During this period, semi-steel rolls and ductile iron rolls appeared successively. After the 1960s, hard alloy powder rolls were successfully developed. In the early 1970s, centrifugal casting technology and differential heat treatment technology were widely introduced in Japan and Europe, greatly improving the comprehensive performance of strip steel rolls. Composite high-chromium cast iron rolls have also been successfully applied to hot strip mills. At the same time, Japan adopted forged white iron and semi-steel rolls. In the 1980s, Europe introduced high-chromium steel rolls, cold rolls for ultra-deep hardened layers, and special alloy cast iron rolls for small steel and wire rod finishing mills. The development of rolling technology has promoted the development of high-performance rolls. Core materials produced using centrifugal casting and new composite methods such as continuous casting composite method (CPC), spray deposition method (fishhook method), electroslag welding method, and hot isostatic pressing method, etc., are made of tough forged steel or ductile iron. Core materials are series of high-speed steel composite rolls and metal ceramic rolls have been applied to the new generation of profile, wire rod, and strip mills in Europe and Japan, respectively.