The backup roll is an important part in the rolling mill. It is used to support the work roll or the intermediate roll to prevent the work roll from flexing and deforming and affecting the output and quality of the plate and strip. The quality characteristics of the backup roll are high surface hardness of the roll body, good hardness uniformity, deep hardened layer of the roll body, good toughness of the roll neck and the body of the roll body; the quality characteristics of the backup roll are high wear resistance, peeling resistance Good and accident resistant. With the development of cold and hot rolling mills towards high-speed, large-scale and high-precision, the requirements for backup rolls are also increasing. In view of the requirements of hard layer depth and residual stress, it is more suitable to use forged steel backup rolls. Compared with the composite cast steel backup roll, the forged steel backup roll has the characteristics of uniform material, better wear resistance and peeling resistance. Large-scale forged steel backup rolls are high value-added products. Due to high technical requirements, complex processes, difficult manufacturing, many production processes, and long cycles, only a few enterprises in my country can produce them, and their output cannot meet market demand, resulting in modern refrigeration. , The large-scale forged steel backup rolls used by hot tandem mill enterprises have to rely on imports.
Back-up roller working conditions and performance requirements:
1. During the rolling process, the backup roll supports the work roll to ensure that the work roll has high rigidity and small deformation during operation. Therefore, the backup roll should have good rigidity.
2. During the use process, the backup roll is always in rolling contact with the work roll or the intermediate roll, which is very easy to produce work hardening. When overloaded, the local yield causes subcutaneous micro-cracks at the bottom of the hardened layer, and the expansion of the micro-cracks eventually causes the roll body to peel off. Therefore, the backup roll is required to have high contact fatigue strength, reasonable stress state and crack growth resistance.
3. The middle of the backup roll will form a concave shape due to wear, and the contact stress at both ends of the roll body will increase sharply, resulting in peeling. Therefore, the roll is required to have excellent wear resistance to delay and reduce the formation of the concave roll shape.
4. The backup roll has a long service cycle, and the roll neck bears alternating bending stress for a long time. In order to prevent the roll neck from breaking, the roll neck is required to have good yield strength, toughness and fracture resistance.
In a word, the perfect combination of high wear resistance, high yield strength and high resistance to peeling of the roll body and high strength, high toughness and fracture resistance of the roll neck is the necessary performance of the backup roll.
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Post time: Mar-28-2022