中文摘要：

评估数控机床的可靠性首先需要根据统计数据判断故障分布类型,并确定故障概率密度函数的参数.根据数控机床常见的故障分布类型,提出了故障统计数据的分组处理步骤,利用最小二乘法对概率密度函数进行参数估计的方法和可靠性指标MTBF的求解方法.利用所述方法对某型数控曲轴磨床的故障分布进行了参数估计和故障概率密度曲线拟合,对两种分布进行了拟合优度比较,对可靠性指标进行了计算.MTBF计算结果与利用定义直接计算的结果较为接近.所提出的可靠性评估方法可以方便地生成计算机程序,为研究数控磨床的可靠性提供了一种方法.

英文摘要：

Fault distribution type identification and probability density function parameters estimation are the prerequisite of CNC grinding machine tools＇reliability assessment. The procedure of fault data grouping, the technique of probability density function parameters estimation based on least square method and the method of reliability index （mean time between failures, MTBF） calculation are proposed. The probability density function parameters estimation and curve fitting, the comparison of goodness of fit, the MTBF solution of some type crankshaft are carried out by the method propased in the paper. The results of statistical calculation and direct calculation by definition are close. The procedure of reliability assessment proposed here can be programmed easily and it provides one measure for reliability assessment of CNC grinding machine tools.