What are the performance requirements for rolls?
Resistant to thermal cracking
Usually, the main requirements for roughing rolls are strength and resistance to thermal cracking; the working roll of a small 20-high rolling mill weighs only about 100 grams, while the weight of the backup roll of a wide and thick plate rolling mill exceeds 200 tons. When selecting rolls, first select the main material for safe load-bearing (various grades of cast iron, cast steel or forged steel, etc.) based on the basic strength requirements of the rolling mill.
hardness
The finishing roll speed is high, and the final rolled product must have a certain surface quality, for which hardness and wear resistance are the main requirements. Then consider the wear resistance that the roller should have when used. Since the wear mechanism of rolls is very complex, including mechanical stress, thermal effects during rolling, cooling, chemical effects of lubricating media and other effects, there is no unified index to comprehensively evaluate the wear resistance of rolls. Since hardness is easy to measure and can reflect wear resistance under certain conditions, the radial hardness curve is generally used to approximately express the wear resistance index of the roll.
Shock proof
In addition, there are some special requirements for the rolls. For example, when the reduction amount is large, the rolls are required to have strong bite ability and be more resistant to impact;
smoothness
When rolling thin-spec products, the requirements for roll rigidity, uniformity of structural properties, processing accuracy and surface finish are stricter;
cutting performance
When rolling steel sections with complex sections, the cutting performance of the working layer of the roll body must also be considered.
When selecting rolls, some performance requirements for the rolls are often contradictory to each other, and the purchase and maintenance costs of the rolls are very expensive. Therefore, the technical and economic pros and cons should be fully weighed to decide whether to use cast or forged, alloy or non-alloy. , single material or composite material.