Coal is China’s basic energy and important chemical raw materials. Coal industry is an important basic industry related to national economic lifeline and energy security. According to the latest data released by the National Bureau of statistics in June 2018, coal accounts for 62.0% of China’s total energy consumption. At present, China is vigorously promoting the adjustment of energy structure, striving to improve the level of clean energy substitution, and plans to reduce the proportion of coal as energy consumption to 58%. However, China is still in the historical stage of accelerated development of industrialization and urbanization, and there is still room for total energy demand to grow. Only by improving the ability of energy self-sufficiency can we grasp the initiative of energy security. Coal accounts for more than 90% of China’s fossil energy resources, and is the most stable, economic and independent energy resource. Therefore, although the proportion of coal in energy consumption will gradually decrease, its main energy status will not change for a long time.
At present, comprehensive mechanized mining is the main mining method in the world’s advanced coal mining countries, including China. Through the unified and coordinated deployment of the main production links (mining, support and transportation) of underground coal mining, it greatly improves the production efficiency of coal mining and significantly reduces the occurrence of mine disasters. Drum shearer (Shearer for short)
Machine is one of the three key equipments in fully mechanized working face. The amount of coal that the shearer can excavate per unit time determines the coal output of the fully mechanized working face, and the cutting parameters of the shearer also determine the quality of the output coal (lump coal rate, gangue rate, etc.).
According to the thickness of coal seam, the power of the shearer ranges from 300 kW to 2500 kW, and the weight of the shearer ranges from 20 tons to 120 tons. It is a typical large complex system integrating mechanical, electrical and hydraulic. Once the shearer is shut down due to failure, it often needs to be transported back to the ground for maintenance, which will lead to the paralysis of the whole fully mechanized working face, and directly reduce the mining efficiency and economic benefits of the enterprise. According to statistics, the comprehensive operating rate of fully mechanized working face in the United States, Australia and other countries has reached more than 90%, while the comprehensive operating rate of domestic ordinary fully mechanized working face is generally lower than 60%, there is still a big gap. Therefore, improving the working reliability of shearer is of great significance to improve the efficiency of national economy and ensure the energy security of our country.
Shearer is mainly composed of cutting part, walking part and intermediate (control) box, as shown in the figure. The cutting part is responsible for cutting and loading coal, and can swing up and down to adjust the height of the drum. When the shearer is working, the front drum cuts the top coal seam on the top, and the back drum cuts the bottom coal seam on the bottom, and adapts to the change of coal seam thickness by adjusting the height of the drum. The walking part is responsible for the moving function of the shearer, which makes the front and rear drum move back and forth in the whole working face to ensure the continuous process of coal cutting and loading. The walking wheel of the walking part is cycloid or involute gear, which is driven by the traction motor through the reduction mechanism. The walking wheel is engaged with the pin rail fixed on the scraper conveyor to realize the traction of the shearer. The communication and control system of the shearer is placed in the middle box, which is responsible for collecting the position and posture data and equipment status data of the shearer in the cutting process, and is responsible for the traction speed regulation and drum height adjustment of the shearer.