| With the development of oil industry, mud-pump has been extensively applied in the oil field exploitation. Gear transmission mechanism, as the significant equipment connecting the prime motor with driving terminal(mud-pump), plays a pivotal role. In the actual project, it needs us to take full account of its operating reliability and practicability in gear transmission mechanism design, owing to the mud-pump performing characteristics, such as atrocious working conditions, serious vibration and shocks, high transmission power. With the thorough study on gear transmission optimal design, the common reliability optimal design contains not only random factors but extensive fuzziness factors, moreover, the latter plays a more important role in obtained results.The gear lubrication problems are the main factor that affects its performance, especially the oil film thickness, which has been extensively in attention. Some international organizations and institutions are preparing for putting the elastohydrodynamic oil film thickness into gear transmission design. Meanwhile,to promote the quality and efficiency and decrease the loading and dynamic stress of gear transmission, the dynamic performance indexes should be applied in static optimal mathematical model by using the vibration theory.According to above questions, this paper combines reliability theory and optimal design method based on the fuzzy mathematics. The fuzzy reliability optimal design with multi-specification restriction and its design quality fuzzy comprehensive evaluation based on entropy method and analytic hierarchy process were researched with the mud-pump gear transmission mechanism as a target. The following works were done.(1) The influencing factors for gear transmission performance were wholly analyzed, the volume calculation method of helical gear and arc bevel gear wheel was inquired, and the independent and controllable design parameters were selected as the independent variable with the minimum volume as objective function. Considering the effects of minimal oil film thickness and critical transmission ratio on gear transmission mechanism, an reliability optimal design mathematical model was established on the basis of reliability theory.(2) Under fuzzy mathematical theory, the fuzzy constraint transfer methods were discussed. The fuzzy constraint condition translation was studied by choosing relevant membership function to transform and the optimal level cut set value was solved by two level fuzzy comprehensive evaluation. Finally, the transformed common constraint was attained, which lays a foundation for the following optimal design model.(3) The relevant optimal design solving method was selected and the problem of dispersed independent variable was investigated on the basis of established model, whose solution was founded by means of Matlab genetic algorithm, and the result was analyzed.(4) After conducting a deep investigation in design quality estimate, with the effective combination of qualitative analysis and quantitative analysis, a scientific and systemic fuzzy comprehensive evaluation was proposed for the mud-pump gear transmission mechanism design quality based on entropy method and analytic hierarchy process.Through the above researches, the volume of the gear transmission mechanism is reduced, and its reliability, lubrication indicators, dynamic performance are effectively improved simultaneously. The correctness and rationalization of optimization method is verified by the analysis of one example finally. |
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