| The high reliability of mining equipment is the basic guarantee for the sustainable and efficient exploitation of coal resources. Coal mining conditions are relatively complex in our country. The mining depth is increasing at a rate of 8~12m per year, and coal mining is still the main source of energy in China. Therefore, making researches on high performance coal mining machine is the only way to realize safe, green and efficient development of coal.Cutting unit is an important part of the shearer and cutting drive system is responsible for the realization of the function of cutting speed and power transmission. At present, the cutting transmission system of the coal mining machine adopts the long chain gear transmission, and the roller speed is not adjustable. In the case of load mutations, transmission system is often subjected to a larger impact load, the reliability of the work components and rocker box deformation has a serious impact. In view of the problems existing in the cutting drive system of the shearer, this paper presents a kind of mechanical-electrical-hydraulic short cut transmission system. For the new type of cutting drive system, this paper mainly focuses on these works:(1)The composition and principle of the cutting drive system are introduced in detail, then, the coupling gear is designed and the power transmission form of planetary gear mechanism is selected. According to the function demand of coal mining machine, the reasonable closed-circuit hydraulic drive system is designed, and the suitable hydraulic components are selected.(2)Established including plunger piston parameter model of pump and hydraulic motor, purely torsional model of coupling gear and planetary gear, drum load model and other components models. Then the short cutting system coupling model is established, the basic performance of individual components is simulated.(3) The effects of pump flow-pressure fluctuation and motor speed-torque fluctuation on the cutting drive system are analyzed. Dynamic characteristics of gear transmission system and hydraulic system under the action of time-varying meshing stiffness excitation are also analyzed. The results show that the time varying meshing stiffness is the main reason for the dynamic response of the gear system. The flow fluctuation excitation of the piston pump has a certain influence on the dynamic characteristics of the cutting drive system, and the influence is gradually decreasing along the direction of the power transmission.(4)The dynamic response characteristics of cutting drive system during load variation, the response characteristics of variable displacement pump during variable speed cutting process and the dynamic characteristics of gear dynamics are analyzed during this process. The analysis results show that the impact load is generated by the abrupt load and the drum speed regulation. The reasonable selection of variable pump parameters can effectively reduce the impact load and improve the reliability of the system. |
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