Air film pressure field characteristics of aerostatic thrust bearing with orifice blockage

Aerostatic bearings are the key component of ultra-precision machine tools, and the bearing performance is critical to the machining accuracy and reliability. The characteristics of the air film pressure field (AFPF) mainly determine the bearing performance and are closely related to parameters such as the air supply pressure, the number, and position distribution of orifices. However, the orifices of aerostatic bearing were usually assumed to be ideal for the available related research. The phenomenon of orifice blockage is common in the actual working conditions, which has great impact on the bearing performance. In this study, the AFPF characteristics of aerostatic thrust bearing was analyzed by the theoretical and experimental way with the commonly single-orifice blockage (SOB) or double-orifice blockage (DOB) cases. The air film pressure distribution, load capacity, and tilting moment are obtained for each case. The effectiveness of simulation results is verified by the experiments. The results indicates that the air film pressure decreases significantly in the area of about three orifices adjacent to the blocked orifice in the condition of SOB. Different cases of orifice blockage have different bearing tilting moment, and resulting in different bearing tilting angle. According to different bearing tilting direction and tilting angle, a preliminary prediction method of the orifice blockage is proposed to judge the different cases of orifice blockage.