In order to realize high speed machining,the special requirements for the transmission and sturctrue of CNC machine tool have to be satisfied.A high speed spindle unit driven by a built-in motor is developed.An oil-wa...In order to realize high speed machining,the special requirements for the transmission and sturctrue of CNC machine tool have to be satisfied.A high speed spindle unit driven by a built-in motor is developed.An oil-water heat exchange system is used for cooling the spindle motor.The spindle is supported by Si4N3 ceramic ball angular contact bearings. An oil-air lubricator is used to lubricate and cool the spindle bearings.Some special structures are taken for balancing the spindle.展开更多
Small sample size problem is one of the main problems that heavy numerical control(NC) machine tools encounter in their reliability assessment. In order to deal with the small sample size problem, many indirect reliab...Small sample size problem is one of the main problems that heavy numerical control(NC) machine tools encounter in their reliability assessment. In order to deal with the small sample size problem, many indirect reliability data such as reliability data of similar products, expert opinion, and engineers' experience are used in reliability assessment. However, the existing mathematical theories cannot simultaneously process the above reliability data of multiple types, and thus imprecise probability theory is introduced. Imprecise probability theory can simultaneously process multiple reliability data by quantifying multiple uncertainties(stochastic uncertainty,fuzzy uncertainty, epistemic uncertainty, etc.) together. Although imprecise probability theory has so many advantages, the existing natural extension models are complex and the computation result is imprecise. Therefore,they need some improvement for the better application of reliability engineering. This paper proposes an improved imprecise reliability assessment method by introducing empirical probability distributions to natural extension model, and the improved natural extension model is applied to the reliability assessment of heavy NC machine tool spindle to illustrate its effectiveness.展开更多
基金This project is supported by National Natural Science Foundation of China(59575063), the Provincial Natural Science Foundation o
文摘In order to realize high speed machining,the special requirements for the transmission and sturctrue of CNC machine tool have to be satisfied.A high speed spindle unit driven by a built-in motor is developed.An oil-water heat exchange system is used for cooling the spindle motor.The spindle is supported by Si4N3 ceramic ball angular contact bearings. An oil-air lubricator is used to lubricate and cool the spindle bearings.Some special structures are taken for balancing the spindle.
基金the National Natural Science Foundation of China(No.51405065)the National Science and Technology Major Project of China(No.2014ZX04014-011)
文摘Small sample size problem is one of the main problems that heavy numerical control(NC) machine tools encounter in their reliability assessment. In order to deal with the small sample size problem, many indirect reliability data such as reliability data of similar products, expert opinion, and engineers' experience are used in reliability assessment. However, the existing mathematical theories cannot simultaneously process the above reliability data of multiple types, and thus imprecise probability theory is introduced. Imprecise probability theory can simultaneously process multiple reliability data by quantifying multiple uncertainties(stochastic uncertainty,fuzzy uncertainty, epistemic uncertainty, etc.) together. Although imprecise probability theory has so many advantages, the existing natural extension models are complex and the computation result is imprecise. Therefore,they need some improvement for the better application of reliability engineering. This paper proposes an improved imprecise reliability assessment method by introducing empirical probability distributions to natural extension model, and the improved natural extension model is applied to the reliability assessment of heavy NC machine tool spindle to illustrate its effectiveness.
