CFD-based investigation and experimental study on the performances of novel back-flow channel aerostatic bearings

Pocketed orifice-restricted aerostatic bearings (PORABs) are broadly used in ultraprecision machining. Increasing the load capacity, stiffness and stability of PORABs is the continuing need for the development of ultraprecision machining. Traditionally, the load capacity and stiffness of PORABs are improved by optimizing the pocket. However, the vortex, which is a critical reason to decrease the bearing stability to influence the precision of machining, always exists in the pocket. Thus, increasing the load capacity, stiffness, and stability of the aerostatic bearings simultaneously is difficult. This paper presents a novel aerostatic bearing with back-flow channels, which are designed to connect the feed pocket and low-pressure region of the bearing clearance directly. Numerical results of air flow show that the high-pressure region of back-flow channel aerostatic bearings (BCABs) can be increased coupling with the vortex in the feed pocket being disappeared. The theoretical load capacity and stiffness of BCABs are larger and higher than those of PORABs. Two experimental test-beds are designed to test the bearing performances. Experimental results of load capacity obtain agree with the predictions greatly. The micro vibration of BCABs measured from the experiments is smaller than that of PORABs. The numerical and experimental results prove that the load capacity, stiffness, and stability of PORABs are increased simultaneously relative to BCABS.