Ziyao Ma

Underground bauxite comprehensive mechanized mining has attracted growing attention, yet regional differences in bauxite characteristics challenge its applicability and economic efficiency. The conical pick, a key cutting tool for this mining method, has cutting load characteristics that directly impact the cutting mechanism’s efficiency and reliability. Three typical bauxite samples from different mining areas were selected as research objects. After testing their composition and firmness coefficients, a linear cutting test bench was used to measure their tri-axial cutting forces at various cutting depths. Regression analysis and the linear fitting of cutting coefficients were conducted to study cutting force and normal force (two core cutting loads). The results show that power functions effectively describe the relationships between the cutting force, normal force, fluctuation coefficient and cutting depth. As the bauxite firmness coefficient and cutting depth rise, the cutting force peak value, fluctuation amplitude and frequency all increase. Excessively high or low cutting coefficients reduce the cutting efficiency; only when both the cutting coefficient and the depth are in an optimal range can the cutting efficiency reach its maximum.

In certain mining areas, bauxite ore exhibits high and uneven hardness, causing frequent overloads in the cutting heads of bauxite mining equipment and challenging the dynamic performance and reliability of its gear transmission system. To investigate the influence of macro-geometric parameters, a dynamic model was built using MASTA software (version 13.0.1). This study systematically analyzed the effects of pressure angle, face width, and bottom clearance coefficient on gear meshing characteristics, service life, and vibration noise under various loads. A preferred set of parameters was determined and validated through vibration and noise tests. The results show that increasing the pressure angle and face width improves gear meshing and fatigue life, while the bottom clearance coefficient has an optimal value of 0.4. Increasing the bottom clearance coefficient exacerbates vibration and noise, with other parameters causing fluctuations under different conditions. The optimal parameters of 23° pressure angle, 75 mm face width, and 0.4 bottom clearance coefficient effectively reduce vibration and noise, providing a theoretical and practical basis for improving the cutting transmission system.

The loading rate of coal is significantly influenced by the number of vanes on shearer drums. However, in actual production, 1400 mm diameter drums feature two-vane and three-vane designs, while 2240 mm diameter ones have three-vane and four-vane designs, with the vane number corresponding to the optimal coal-loading rate remaining unclear. To reveal the correlation between vane number and coal-loading rate for such drums, parameters were calibrated through multiple physical tests in this study. Supported by field data, simulation analyses were conducted via the discrete element method to investigate the effect of the vane number on the drum coal-loading rate under different moisture contents and traction speeds. The results indicated that particle adhesion initially increases and then decreases with the moisture content, with the peak characteristics influenced by the particle size. Particle movement during drum coal mining is jointly governed by multiple factors. For 1400 mm drums, two or three vanes should be selected depending on moisture fluctuations and coal transportation requirements, whereas for 2240 mm drums, three or four vanes are recommended based on the balance between coal-cutting volume, conveying capacity, and traction speed.