Impact of Hydrostatic Bearings on the Dynamic Performance of Electric Spindle Rotor Device
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摘要: 静压轴承的性能对高精密平面磨床电主轴转子系统的动态特性起决定性的影响。以某高精密平面磨床电主轴转子系统为研究对象，应用弹簧阻尼单元模拟静压轴承，建立电主轴转子系统的有限元模型，分析其动态特性，得到静压轴承刚度及阻尼值对电主轴转子系统固有频率、动刚度及临界转速的影响特点。结果表明：前后端静压轴承刚度相同时，电主轴转子系统固有频率、临界转速与轴承刚度、阻尼成正变关系，动刚度与轴承刚度成反变关系与轴承阻尼成正变关系，轴承刚度大于3×105 N/mm时，轴承阻尼值对系统临界转速影响很小，此时提高轴承阻尼值可以提高系统固有频率和动刚度，减小振动幅度，获得良好的动态性能；前后端静压轴承刚度不相同时，轴承刚度的波动对系统最小动刚度的影响比轴承刚度相同时更柔和，加工更稳定。Abstract: Performance of hydrostatic bearing plays a decisive influence on dynamic performance of spindle rotor device in high-precision planar grinding machining. Based on the electric spindle rotor device of a high-precision planar grinding machining, the finite element model of electric spindle device is established, finding out how the hydrostatic bearing stiffness and damping values affect the natural frequencies, dynamic stiffness and critical speed of electric spindle rotor device. When the stiffness of front and rear hydrostatic bearings is the same, the natural frequencies of electric spindle rotor device have positively change relationships with the hydrostatic bearing stiffness and bearing damping; the dynamic stiffness has positively change relationships with the bearing stiffness and negative change relationships with the bearing damping; the critical speed has positively change relationships with the bearing stiffness. When the bearing stiffness is greater than 3×105 N/mm, the bearing damping has little impact on the critical speed, at this point increasing the bearing damping value can improve the natural frequencies and dynamic stiffness, reduce vibration amplitude, achieving good dynamic performance. When the stiffness of front and rear hydrostatic bearing is different, the impact of bearing stiffness fluctuations on the minimum dynamic stiffness of the device is gentler compared with when bearing stiffness are the same, consequently the influence on the machining accuracy is more stable.
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Key words:
- bearings(machine parts) /
- damping /
- dynamics /
- finite element method /
- grinding(machining) /
- natural frequencies
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