Research on the contact characteristics of rocker arm gears in shearer under lubrication containing coal powder impurities

To study the contact characteristics of the shearer rocker arm gear transmission system under lubrication containing coal powder impurities, the MG500/1130 shearer rocker arm transmission system was selected as the research object, and a gear elastohydrodynamic lubrication (EHL) model was constructed based on Hertz-Reynolds theory. Considering the impact of coal powder impurities on the viscosity of the lubricant, the kinematic viscosity of coal powder-laden lubricant was measured under different coal powder particle sizes, concentration ratios, and temperatures using a mixed orthogonal experimental method. A polynomial fitting method was employed to establish the functional relationship between particle size, concentration ratio, temperature, and viscosity of the lubricant. A multi-software collaborative simulation approach was used to construct a simulation model of the shearer rocker arm gear transmission system, analyzing the effects of coal powder-laden lubricant with different particle sizes and concentration ratios on gear contact stress and lubricant film thickness. The results indicate that, under four different conditions of coal powder particle size and concentration, the maximum contact stress of the Z1 gear in the rocker arm transmission system ranged from 1134 to 1177 MPa. As the particle size and concentration of coal powder increased, the maximum contact stress of the Z1 gear showed a decreasing trend. Additionally, under the same coal powder particle size and concentration, the contact stress of the gears near the output end was significantly higher than that of the gears near the input end. The minimum lubricant film thickness during gear meshing under the four conditions varied between 0.08 μm and 0.26 μm. Furthermore, the coal powder particle size and concentration in the lubricant were positively correlated with the lubricant film thickness: larger particle sizes and higher concentrations resulted in greater minimum lubricant film thickness. These findings provide theoretical support for improving the reliability of the shearer rocker arm transmission system.