Design And Performance Analysis Of Bi-conic Hydrostatic Bearing

Hydrostatic support technology is a support method that can achieve high precision,high stiffness and large damping,which has a very important position in the field of ultra-precision machining.Hydrostatic bearings are the core functional components of hydrostatic rotary tables and hydrostatic spindles.Their design and development are of great significance for the study of these critical equipment.The main research content of this paper is based on the application and working principle of hydrostatic bearing.By theoretical studying of the bearing characteristics and the oil film characteristics inside the bearing under the condition of slit throttling,a hydrostatic bearing with bi-conic structure is developed and finally test its basic properties such as load capacity,stiffness and rotation accuracy are tested.Firstly,through the principle of slit throttling,the design parameters of the spindle and the requirements for use,the bi-conic hydrostatic bearing was selected as the supporting member for the rotary motion of the spindle.The entire design includes the design of the bearing structure,the oil circuit system,the pneumatic system and the motion control system,which focus on the influence of the step parameters and the gap size of the inherent flow control on the bearing performance.The static performance of the bearing is mainly guaranteed by the internal clearance of the bearing.Based on the structural characteristics of the oil film inside the bearing and the inherent flow control principle,a suitable mathematical model of bearing lubrication is established.By comparing and analyzing the bearing capacity and oil film stiffness of different step sizes and different bearing clearances,it is concluded that the optimum step sealing oil surface length ratio S=0.1 and height dimension ratio G=2.4.The modal analysis of the bearing was carried out by ANSYS,and the natural frequency and vibration mode of the bearing motion were obtained.The pressure distribution of the oil film inside the bearing of different structures was analyzed by FLUENT.The influences of the design of the step sealing surface,the bearing eccentricity,the bearing speed and the oil supply pressure on the oil film pressure distribution and bearing performance were obtained.The hydrostatic bearing that basically meets the design requirements was developed.The accuracy of theoretical calculation and FLUENT simulation analysis was verified by load capacity and stiffness experiments.The effectiveness of the bearing gas seal system was verified by the sealing test.