Three Weibull distributions are put forward to evaluate the reliability on the basis of two Weibull distributions which can accurately reflect the quality index of CNC lathes.

• 实际上,根据现场获得的数据,首次故障时间并不为零,在二参数威布尔分布可靠性评价的基础上,又提出三参数威布尔分布的可靠性评价,可以更精确地反映出数控机床的各项指标。