What Is The Function of The Grinding Rolls in The Grinding Mill?

Rollers are the most crucial grinding components in mills, especially roller mills such as vertical mills and roller presses. Their main function can be summarized as applying tremendous pressure to materials, causing them to be crushed, ground and turned into fine powder.

Core Function: Crushing and Grinding

This is the most fundamental role of the rolls. After the material enters the mill, it is sent between the rolls and the grinding plate (or grinding ring).

• Applying pressure: Under the action of the hydraulic system or springs, the rolls exert an enormous pressure (up to several hundred tons) on the material bed moving on the grinding table.

• Extrusion crushing: The material is first crushed under high pressure, generating a large number of fine particles and cracks.

• Shearing and grinding: Due to the relative speed difference between the rolls and the grinding discs, while extruding, a shearing force is also exerted on the material, further grinding it into finer powder.

Form a stable material bed

The combination of the rolls and the grinding disc can form a stable and moderately thick material layer (referred to as the "material bed"). A stable material bed is the prerequisite for efficient grinding, and it can:

• Uniform force application: Ensure that the pressure is evenly distributed over the majority of the materials, thereby enhancing the grinding efficiency.

• Buffer protection: An excessively thick material bed can prevent the rolling mill rolls from directly contacting the grinding disc, thereby reducing wear and vibration.

Affecting product fineness and output

The working condition of the rolls directly determines the quality (fineness) of the final product and the output of the mill.

• Pressure adjustment: By adjusting the pressure applied to the rolls, the degree of material pulverization can be controlled. The greater the pressure, the finer the product, but energy consumption will also increase; if the pressure is reduced, the product becomes coarser and the output may increase.

• Wear condition: The degree of wear on the surface of the roller will affect the grinding efficiency. The severely worn roller surface becomes uneven, which will reduce the grinding effect, leading to a decrease in output and uneven product fineness.

The key to energy transfer

The energy generated by the drive device (motor) of the mill is mainly transferred to the materials through the rolls, to overcome the internal crystal force of the materials and cause them to deform and break. Therefore, the rolls are the key components for energy conversion and performing the crushing action.

In summary, the rolls are the "heart" of the mill. Through high-pressure compression and shearing grinding, they transform the blocky or granular raw materials into the required fine powder. Their performance directly determines the efficiency, energy consumption and product quality of the entire grinding system.