Due to mineral sizer crusher, the ratio of coal particle hardness Hm to grinding roller hardness Ha is higher than 1.3, so the wear behavior between grinding roller surface and coal particles of grinding mill belongs to coal wear. There are three main wear mechanisms of abrasive particles, namely microscopic chip, extrusion spalling and fatigue failure.
The current research on the coal wear problem is as follows: The analysis shows that the coal has hardened in the wear process, the hardness is higher than that of the grinding material, and the essence is still hard abrasive wear. The cyclic frictional stress field, subsurface cracks and deformation fatigue were found in the wear process. In addition, the ploughing phenomenon and wear difference of a small amount of hard abrasives cause the wear surface to fall off, and the friction temperature rise increases the hardness of soft abrasive particles and accelerates the wear. It is thought that hard particles in coal cause wear on soft parts in hard materials. We believe that the coal produces elastic deformation on the contact surface, and if the abrasive toughness is suitable, plastic deformation will appear and extend on the contact surface. The two produce sufficient friction and shear stress concentration, resulting in the wear of the tooth roller of mineral sizer crusher. We believe that this phenomenon is fatigue wear. The tooth roller of mineral sizer crusher produces complex stress state when it contacts with materials. The contact section is the compression zone and the non-contact section is the tension zone.
Mineral sizer crusher tooth roller is subjected to cyclic alternating load, resulting in roller surface wear due to cumulative damage. It is considered that the soft coal is in solid state and incompressible, and can resist the roll surface with greater force when it is pressed into the crushing area. Therefore, extrusion, grinding and shear stresses exist on the surface of tooth roller of mineral sizer crusher and coal abrasives. Due to the thermal energy converted by mechanical energy, the temperature of the rotating roll rises to 60-80℃, and the fatigue stress concentration can be formed at the micro-contact point between the abrasive and the metal surface when the abrasive is crushed, and the higher temperature is generated instantly to make the surface of the grinding roll soft and wear. The microstructure analysis of the wear surface of the grinding roll shows that the wear mechanism of the grinding roll is that the subsurface carbide breaks and cracks first, resulting in the stripping wear of the matrix. Secondly, the cracks on the carbide near the surface of the subsurface extend to the surface, and the roll surface wears gradually through plastic fatigue and multiple impact fatigue.
