Development of an Infinite-Stiffness Aerostatic Bearing

两种类型的主动限流器用于获得无限刚度空气静压轴承。主动限流器之一是空气静力学控制限流器（ACR），其并入空气静力学推力轴承中。推力轴承的推力板直径为65mm。主动节流器的开度由空气静压轴承控制，主动节流器的特性可以很容易地改变，轴承刚度可以调节到无穷大。当供油压力为0.49MPa时，轴承的推力刚度可以无限大，载荷小于240N。也可以实现负推力刚度。另一种主动限流器是排气控制限流器（ECR），它被集成到两排空气静压径向轴承中。径向轴承的孔径为40mm。ECR的打开由压电致动器控制，压电致动器由微计算机控制。当供油量为0.49MPa时，轴承的径向刚度可以无限大，载荷小于70N。这些无限刚度推力轴承和径向轴承组合起来构成一个空气主轴。空气主轴的旋转精度在轴向小于20nm，径向小于50nm。当载荷为

Two types of active restrictors are used for obtaining infinitestiffness aerostatic bearings. One of the active restrictors is an Aerostatically Controlled Restrictor(ACR), which is incorporated into an aerostatic thrust bearing. The diameter of the thrust plate of the thrust bearing is 65mm. Opening of the ACR is controlled by an aerostatic bearing, and the characteristic of the active restrictor can easily be changed, and the bearing stiffness is adjusted to be infinite. When the supply pressure is 0.49MPa, the thrust stiffness of the bearing can be infinite for the load smaller than 240N. Negative thrust stiffness can also be realized. Another active restrictor is an Exhaust Control Restrictor(ECR), which is incorporated into a two-row aerostatic radial bearing. Bore diameter of the radial bearing is 40mm. Opening of the ECR is controlled by a piezoelectric actuator which is controlled by a micro computer. When the supply is 0.49MPa, the radial stiffness of the bearing can be infinite for the load smaller than 70N. These infinite-stiffness thrust bearing and radial bearing are combined to construct an air spindle. Rotational accuracy of the air spindle is less than 20nm in the axial direction, and less than 50nm in the radial direction. Infinite stiffness can also be obtained when the load is