Rollers play a vital role in the rolling process. They rely on friction between the rotating rollers and the rolled piece. This friction drags the rolled piece into the gap between the rollers, compressing it to produce plastic deformation. Rolling aims to shape, size, and improve the performance of the rolled material. Rollers, which directly contact the rolled piece, cause the metal to deform. They are consumable parts and significantly affect production quality, efficiency, and costs. High-end rolling equipment often uses forgings for rollers to improve the process.
Working Characteristics of Rolling Mill Rollers
Rollers withstand large rolling pressure and torque during work. Sometimes, they face dynamic loads. For instance, primary rolling mill rollers endure large inertia and impact.
Rollers work under high temperatures or experience large temperature changes. The rolled piece’s high temperature and cooling water exposure cause hot and cold conditions. These conditions lead to cracks under alternating stress. In cold rolling, rollers face high contact stress and rolling pressure, making their working conditions extremely challenging.Constant wear affects rolled product quality and roller life.
Working Conditions of Cold Rolling Mill Rollers
Cold rolling rollers endure large rolling cycle stress and strong friction. Their working conditions include:
- High and uniform surface hardness, usually above 62HRC.
- A deep hardened layer with lower hardness at the roller edge.
- Lower hardness at the roller neck.
- Sufficient resistance to cracking and peeling caused by torsional, bending, and shear stress.
- High wear resistance, contact fatigue strength, fracture toughness, and thermal shock strength.
Working Conditions of Hot Rolling Mill Rollers
Hot rolling rollers work in high temperatures of 700℃~800℃ and withstand strong rolling forces. Their working conditions are:
- High hardenability.
- Low thermal expansion coefficient.
- High thermal conductivity and high-temperature yield strength.
- High oxidation resistance and high-temperature creep strength.
- Excellent tempering resistance and uniform surface hardness.
By understanding and optimizing these working conditions, steel mills can enhance production efficiency, product quality, and roller longevity.
