How to Prevent the Hazards of Rolls and Improve Work Efficiency?

Among the rolling mill components, the operating conditions of the rolls are the messiest. Residual stress and thermal stress will occur in the preparation process before the roll is manufactured and used. During the working process, it is further subjected to the effects of various periodic stresses, including twists, changes, shear forces, contact stresses, and thermal stresses. The distribution of these stresses along the roll body is uneven and constantly changing. The reason is not only the planning factors, but also the continuous changes of the roll wear, temperature and roll shape during use.

In addition, abnormal rolling conditions often occur. If the roll is not properly cooled after use, it will also be harmed by thermal stress. Therefore, in addition to abrasion, the roller often shows various partial damages and surface damages such as cracks, cracks, shedding, and indentation.

A good roll should have a better match between its strength, wear-resistance and various other performance indicators. In this way, it is not only durable under normal rolling conditions, but also less damage when presenting some abnormal rolling conditions. Therefore, when making rolls, the metallurgical quality of the rolls must be strictly controlled or supplemented by external measures to enhance the bearing capacity of the rolls.

Reasonable roll shape, pass, deformation criteria and rolling conditions can also reduce the work load of the roll, prevent part of the peak stress, and extend the life of the roll. The reason is related to the residual stress of the roll itself, the mechanical stress during rolling and the thermal stress of the roll, especially when the temperature difference between the outer surface of the roll body and the core part is large. This temperature difference can be caused by poor roll cooling, discontinuation of cooling, or overheating of the roll surface at the start of a new rolling cycle. The infinite temperature difference between the outer surface of the roll and the core leads to a large thermal stress. When the large thermal stress, mechanical stress, and residual stress of the roll exceed the strength of the core of the roll, the roll breaks.

The cold welding repair method can be used to repair the broken roller. Cold welded rolls use the principle of high-frequency electric spark discharge to perform non-thermal surfacing welding on the metal surface, so it will not deform, anneal, undercut and residual stress during the process of repairing the defects of rolls such as sand holes and scratches, and does not change the metal arrangement. . The correction accuracy is high. The thickness of the coating ranges from a few microns to a few millimeters, which can correct the defects of metal workpieces such as wear, scratches, pinholes, cracks, defect deformation, hardness reduction, trachoma, damage, etc. It can also be used for turning, milling, planing, grinding and other mechanical processing, as well as electroplating and other post-processing.