多台数控机床强度函数浴盆曲线建模技术研究
Research on Intensity Function Bathtub Curve Model for Multiple CNC Machine Tools

为了准确描述复杂产品故障过程的浴盆曲线趋势,建立多台数控机床的强度函数浴盆曲线模型,并采用极大似然方法对模型进行参数估计。利用基于试验总时间(TTT)的趋势检验方法验证故障过程的浴盆曲线趋势。从浴盆曲线两转折点的可靠性含义出发,对累计平均无故障工作时间进行分析,提出一种确定浴盆曲线转折点的方法。通过对3台数控磨床的实例计算和分析,说明本文模型与方法在实际应用中的有效性。
To accurately describe the bathtub curve trend of complex products during the failure process, the intensity function bathtub curve model for multiple CNC machine tools is built, and its parameters are estimated through Maximum Likelihood Estimation, along with some numerical method. The hypothesis testing for trend based on TTT(Total Time on Test) is introduced and applied to test and verify the bathtub failure trend. Considering the reliability implication of two turning points of bathtub curve, we propose a method of determining the turning points on the basis of analyzing features of the cumulative mean time between failures. The model and method proposed in this paper are demonstrated to be effective in practical applications, through computing and analyzing failure data of three CNC grinding machines from field test