基于可靠性分析理论的数控磨床故障排查方法

鉴于目前国内对数控磨床研究较少且相关数据匮乏,对某机床厂生产的30台MSK系列外圆数控磨床的故障情况采用无替换定时截尾试验方法进行了长期跟踪统计,分别根据故障模式和子系统对数控磨床的故障数据进行分组划分,找出故障频发的故障模式,并结合所提出的基于子系统算法的敏感度分析方法(sensitivity analyze,SA)求得对整机可靠性影响最大的关键子系统为电控系统(electrical control,EC),该系统的可靠性指标平均无故障时间(mean time between failure,MTBF)提高10%,可使整机MTBF提升2.06%,敏感度远高于其他子系统。为提高电控系统可靠性,采用故障树分析(fault tree analyze,FTA)对电控系统进行故障排查找出该系统故障频发的原因,采用上行法对该故障树进行定性分析,根据求得的29个最小割集发现,造成该系统故障频发的主要原因是外购外协零部件的可靠性较差。通过改善和优化,最终使得整机的可靠性提升至1500 h,验证了所提方法的有效性。

Troubleshooting method of CNC grinding machine based on reliability analysis theory

In view of the lack of research and related data on CNC grinders nowadays,the failure situation of 30 MSK series cylindrical CNC grinders manufactured by a machine tool factory was tracked and counted for a long time by using the method of non-replacement timing truncation test.To find out frequent failure modes,the failure data of CNC grinders were grouped according to the failure mode and subsystems respectively.It is result that the key subsystem which has the greatest impact on the reliability of the whole machine is the electronic control system(EC),while the mean time between failures(MTBF)of the system is increased by 10%,the MTBF of the whole machine would be able to increase by 2.06%.Then,in order to improve the reliability of electronic control system,FTA(Fault Tree Analysis)was used to find out the causes of frequent faults in the system.The qualitative analysis of the fault tree,via utilizing Semanderes method,obtained the 29 minimum cut sets,while the main cause of frequent faults in the system is the poor reliability of outsourced parts.By improving and optimizing,the MTBF of the whole grinding machine is improved to 1500 hours,which verifies the effectiveness of the proposed method.