随机载荷冲击下采掘机械截齿竞争失效可靠性分析

Reliability analysis of mining machinery pick subject to competing failure processes under random load shock

采掘机械的高效运行是煤矿企业降低生产成本,提高生产效率,实现利润最大化的主要途径之一。截齿作为采掘机械的关键消耗部件,其可靠性直接决定了采掘机械的工作性能和使用寿命。在采掘过程中,将煤岩视为正常工作载荷,将矸石和断层视为随机冲击载荷。截齿受煤岩引起的自然磨损及矸石和断层引起的载荷冲击的影响,其失效是磨损退化导致的软失效和随机载荷冲击导致的硬失效相互竞争的结果。由于矸石和断层具有一定的体积和硬度,随机载荷冲击会持续一定的时间,并在不同硬度下对截齿的磨损产生不同的加速作用。同时,截齿抵御致命性冲击的能力会随着磨损程度的增加而减弱。通过考虑持续冲击、变速率加速退化和硬失效阈值变化对截齿磨损的影响,研究了随机载荷冲击下截齿竞争失效的可靠性建模。首先,通过同时考虑自然磨损退化、冲击瞬时退化以及冲击持续时间内的变速率加速退化,构建了随机载荷冲击下截齿的退化模型。其次,在此基础上构建了竞争失效模式下截齿的可靠性模型。最后,基于工程数据对截齿的可靠性模型进行了数值实验和有效性分析。结果表明考虑持续冲击、变速率加速退化和硬失效阈值变化的截齿竞争失效可靠性模型符合工程实际,为截齿的设计优化、维修决策和备件管理提供了理论基础。

Efficient mining machinery operation is essential for coal mining enterprises to reduce production costs,improve production efficiency,and maximize profits.As a key consumable part of mining machinery,the reliability of machine picks directly determines the operational performance and service life of the machinery.During the mining process,the coal and rock are regarded as normal working loads,the gangue and faults being regarded as random shock loads.The picks can be affected by natural wear and tear caused by the coal and rock,and by load shocks caused by the gangue and faults.The pick failure is the result of the competing influence of soft failure caused by natural wear and tear and hard failure caused by random load shocks.Because the gangue and faults have a certain volume and hardness,a random load shock may last for a certain period of time,producing different acceleration effects on the pick wear under different hardness.At the same time,the ability of the pick to resist the fatal shock may be weakened as the wear degree increases.The reliability of the pick competing failure process under random load shocks is modeled by considering the influence of continuous shocks,the accelerated degradation at changing rates during shock periods,and the changing hard failure threshold on the pick wear.Firstly,the pick-degradation model under random load shocks is established by considering the natural wear degradation,instantaneous shock degradation,and accelerated degradation at changing rates during shock periods.Secondly,the pick reliability model under the competing failure mode is established on this basis.Finally,a numerical experiment and an effectiveness analysis of the pick reliability model are conducted based on the engineering data.The results show that the competing failure reliability model of the pick considering continuous shocks,a changing degradation rate and changing hard failure threshold is in line with engineering practice,which provides a theoretical basis for pick design optimization,maintenance decision and spare parts management.