Rollers are subjected to bending, friction, impact, and other effects during the rolling process, which mainly cause peeling and wear of the roll surface. Therefore, the roll surface is generally required to have high strength, hardness, wear resistance, and fatigue limit. These surface properties are not only related to the material of the roll but also to the surface treatment process of the roll. The surface treatment process of the roll mainly includes the overall quenching process of the roll, the induction heating quenching process, the surfacing process, the thermal spraying process, the thermal spraying process, and the laser surface modification process. Our company can provide tungsten rollers of various shapes and sizes. If you need to order, you can contact us by email.
1. Overall quenching process
Integral quenching is to uniformly heat the entire roll to the austenitizing temperature for quenching, and at the same time, the roll neck is protected by insulation material to ensure that it maintains good toughness. The overall quenching process will cause high residual compressive stress on the roll surface, making the roll have the disadvantages of a shallow hardened layer, weak matrix, and poor accident resistance.
2. Induction heating quenching process
The induction heating quenching process uses a high-frequency AC magnetic field to heat the roll twice in succession so that the roll surface is quickly heated to above the critical temperature, and then quickly cooled to obtain martensite.
3. Overlay welding process
After the roll is damaged, its surface needs to be repaired. Overlay welding is a commonly used repair process, which is to melt the metal by electric welding or gas welding and pile it on the roll surface. Although the overlay welding process can ensure the wear resistance of the roll, the entire process is too complicated, the productivity is low, and the technical requirements for workers are high. At the same time, the roll will produce pores, cracks, slag inclusions, and other problems during overlay welding.
4. Thermal spraying process
The thermal spraying process is to spray the molten or semi-molten spraying material on the roller surface at high speed to form a micro-metallurgical bonding or mechanical bonding coating. Due to the low bonding strength between the coating and the substrate, mainly mechanical bonding, the coating has gaps and residual stress, which makes the toughness and machinability of the roller poor.
5. Thermal spraying process
The thermal spraying process is based on the thermal spraying process. The spray layer is remelted again to make the spray layer and the substrate surface material reach a molten state, and then a tighter metallurgical bonding layer is further formed. Thermal spraying can be regarded as a combination of alloy spraying and metal surfacing. It overcomes the shortcomings of low bonding strength and low hardness of the thermal spraying layer. At the same time, due to the use of high-alloy powder, the spraying layer has a series of special properties, which are not available in general surfacing.
6. Laser surface modification process
Laser strengthening is to irradiate the roller with a high-density, high-power laser beam to increase the surface temperature of the roller instantly, thereby causing the surface organization of the roller to be modified. Therefore, it has a series of advantages such as high automatic control accuracy of the heat treatment area, the highly refined structure of the strengthening area, small thermal deformation of the workpiece, and the use of point processing or line scanning processing to obtain a discrete strengthened surface with the same softness and hardness, strength and toughness.
