Coal is not only the basic energy of our country, but also an important industrial raw material. With the rapid development of coal mining mechanization, over the past decade, China’s annual coal output has continuously reached new highs, the reserves of medium thick coal seams that are easy to mine in major mining areas have been continuously reduced, and the proportion of thin and extremely thin coal seams has increased. In order to avoid resource waste and realize balanced mining of coal resources, many mining areas have increased the mining of thin and extremely thin coal seams. Due to the high mining height, high mining labor intensity and bad working conditions of thin coal seam, in order to ensure the production efficiency, it is necessary to achieve efficient mining, which objectively determines the development of thin coal seam shearers towards high power density.
Planetary transmission gear system has many advantages, such as compact structure, small mass, large bearing capacity, high energy density, high transmission efficiency and so on. Due to the mining height, the thin seam shearer is equipped with a drum with smaller diameter. In order to ensure a good coal loading effect, the radial size of the planetary transmission gear inside the drum is limited. Due to the special geological conditions of thin coal seams in China, narrow cutting depth mining is adopted, and the axial size of planetary transmission gear is subject to the body and mining depth. The above-mentioned objective factors seriously restrict the development process of high power density of thin seam drum shearers. On the premise of ensuring the reliable operation of the shearer, it is of great practical significance to optimize the design of its rocker planetary transmission gear system.
In the process of traditional shearer design, researchers only check the contact and bending fatigue strength of rocker planetary gears; The selection of safety factor is mainly based on empirical data, which has some shortcomings such as excessive design margin and imprecise design. The shearer in medium thick coal seam has large size, fast heat dissipation and good mining conditions, and is less affected by the traditional design. However, this method is not conducive to the modern design of high power density thin coal seam shearers. In order to better solve the shortcomings of traditional design and realize the characteristics of low mining height, small volume and high power density; Taking the NGW type planetary transmission gear inside a thin seam shearer as an example, taking the total volume of the planetary transmission gear as the objective function, the mathematical model of the transmission system structure is established, and the modern optimization design theory and method are fully used to optimize its solution and research.