This article proposes a usage of rough collection theory by optimizing the BP nerve network model method, and will apply the optimized network model in the rolling bearing breakdown diagnosis.

提出了使用粗糙集理论优化BP神经网络模型方法，并将优化后的网络模型应用于滚动轴承的故障诊断中。

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The fatigue life for hybrid rolling ball bearing is researched on the base of its breakdown mechanism and fatigue life of steel bearings. Its fatigue life formula is given.

根据混合轴承的破坏机理，在钢轴承使用寿命公式的基础上，对混合轴承的使用寿命进行探讨，推导出它的寿命公式。

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Likewise, the increase in services mentioned above means, in the event of a breakdown, there is less spare rolling stock for contingency use.

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