小子样高速电主轴寿命分布模型参数估计

Parameters estimation of lifetime distribution model of high-speed motorized spindle with small-scaled sample

为分析高速电主轴的可靠性,需测试小子样电主轴性能退化量,以此评估高速电主轴的可靠性指标。该方法首先假设电主轴寿命分布模型,估计小子样电主轴模型参数,检验并确定电主轴寿命分布模型。针对Weibull寿命分布模型,应用修正极大似然函数推导了小子样高速电主轴寿命分布模型参数估计式,并应用经验分布函数检验分布模型及参数估计值。为验证参数估计方法的正确性,利用两根170MD18Y16型高速电主轴试样轴端跳动量测试数据和参数估计式,完成该型电主轴分布参数估计,拟合检验结果为寿命服从Weibull分布,且模型参数估计为真值;据此参数值确定的170MD18Y16型电主轴特征寿命与实际失效寿命值一致,表明分布模型参数的修正极大似然函数估计方法正确,可用于小子样高速电主轴的可靠性评估。

In order to analysis the reliability of high-speed motorized spindle, the degradation performance of high-speed motorized spindle with small-scaled sample was tested. And the reliability index of high-speed motorized spindle was evaluated based on this. The lifetime distribution model of spindle was assumed first. The model parameters of motorized spindle with small-scaled sample were estimated. Aiming at the Weibull lifetime distribution model, the maximum likelihood function was adopted to deduce the lifetime distribution model parameter estimation function of high-speed motorized spindle with small- scaled samples. In order to verify the feasibility of parameter estimation, the shaft end run-out testing data of two 170MD18Y16 motorized spindles and the estimation formula of parameters were used to estimate the parameters. The Weibull model and the estimation value of parameters was true according to the fitting-test. The characteristic lifetime of 170MD18Y16 motorized spindle achieved by these parameters is consistent with the actual value. The result indicated that the modified function of maximum likelihood estimation method was correct. This could be applied to evaluate the reliability of high-speed motorized spindle with small-scaled sample.