| As an important component responsible for the mechanized mining, the maintenance work of the cutting transmission system has been a top priority of the shearer.Moreover, the requirement for mining technology in mechanized mining face is increasingly stringent, and the higher quality and performance requirements are needed. Therefore, the design for cutting transmission system is becoming more and more significant. However, in the designprocess of the cutting transmission system, the reliability is undoubtedly a key factor, and a comprehensive reliability evaluation of the cutting transmission system is conducted so as to control its probability of failure and improve the reliability.In order to reduce the operation risk of the cutting transmission system, a set of reliability analysis system applied to the cutting transmission system is proposed in this thesis. The main research contents and conclusions are presented as follows:(1) The reliability analysis model of the cutting transmission system was established by analyzing the structure and functional principle of the cutting transmission system. And then the agreed level and analysisprocess of reliability analysis were developed according to the relevant reliability analysis standards. Furthermore, the reliability of the cutting transmission system was analyzed based on the FMEA analysis method, and the failure mode database was generated, as well as the analysis report.(2) As for the reliability analysis technology FMECA and FTA, the analysis principle, the basic process, analysis purpose and significance as well as the precautions in analysis process wereintroduced. Comparing the advantages and disadvantages of FMECA and FTA, an FTF comprehensive reliability analysis method was proposed by taking advantage of two methods’ advantages and contact, and a comparative analysis of the forward and inverse FTF analysis was given as well. The FMECA analysis of the cutting transmission system was conducted by adopting the forward FTF reliability analysis method, and then FTA analysis was carried on in accordance with the top event which has high RPN value and hazard value in class I and II event. Furthermore, the cause of the malfunction and the risk parameter were gotten based on FTA analysis, also the evaluation parameters of system health states were obtained. On the basis of the research and analysis above, improving measures for the weak links of cutting transmission system were put forward.(3) For gear fault can be demonstrated by the gear meshing kinetic parameters, particularly, gear meshing stiffness and strength are sensitive to gear fault, analysis of gear meshing kinetic parameters is the basis of gear accurate fault diagnosis. Established a mathematic model of solving gear time-varying mesh stiffness based on materials mechanics and energy principles, afterwards, proposed a mathematic model of solving gear time-varying meshing stiffness with crack propagating along tooth width and crack depth. Because the high-speed zone in cutting transmission system is the high incidence of gear failure, a 9-degree-of-freedom dynamic model was proposed for the high-speed zone in ranging arm, with the model the dynamics of the high-speed zone, the influence of impact load on the high-speed zone gears, and the influence of gear with different crack width and length were analyzed, the results shown that the gear failure could be found by time-domain signal analysis.(4) According to the impacts of strong noise in the mine, the nonlinearity generated by gear transmission and the non-stationary vibration signals, the fault diagnosis model based on multi-sensor information fusion is established. The fault feature information is extracted by wavelet correlation feature scale entropy, the single sensor recognition is conducted by SOM neural network structure and then the multi-sensor information fusion is carried on by D-S evidence theory. Therefore, the key problems including recognizing the fault type under background of strong noise and eliminating uncertainties of recognition are solved.(5) The finite element analysis of the shearer cutting system is studied on by ANSYS, and its stress concentrated parts are determined. In the end, the design reliability of the shearer cutting system is developed by optimizating the stiffener structure. In line with the study on improving the mechanical property of shearer’s shell based on special casting steel materials, the reasonable and stable casting process of shearer cutting system is designed and the processing route is planned. The material and the composition are determination based on the mechanical properties and the tilling capacity of metallic liquid, and it is better to cast a mould shell of the shearer cutting system with good comprehensive mechanical properties. The acceptance test for mould shell shows that the precision of the processing route arrangement and the machining process design can satisfy machining requests. During underground application, the service performance of shearer cutting system can keep in a good condition, and the comprehensive mechanical properties can satisfy the operating requirements of the large power shearer.(6) By analyzing the high and low speed seals in shearer cutting transmission system and the problems in use, the test device of floating seal are developed. Moreover, the sealing performances of floating seals from different factories are copared according to the test device and the loading experiment, and the seal with superior performance as well as the best assembly space are screened out. Finally, measures to improve the reliability of the high and low speed seals, the damaged detection method and maintenance measures of the seals are proposed.At the end of this thesis, the summarizations of the research and expectation of the related technology development are presented. |
