| The spindle is an important part of the rotating machinery system,and its motion accuracy affects the performance of the system directly,as the core part of the spindle,the performance of the bearing is particularly important.Therefore,studying and improving the motion accuracy and performance requirements of bearings is of great significance for the development of precision machining.During the operation of the mechanical equipment,the bearing is subjected to both axial and radial loads,especially for the hydrostatic thrust bearing,the axial load is more prominent.Due to the errors in the machining process,resulting in dimensional errors in the end faces of the bearings in various degrees,coupled with the axial vibration and temperature rise in the working conditions,these all determine that the thrust bearings will inevitably produce axial forces during operation.As a result,end surface fluctuations occur,which has an important influence on the accuracy of the machining.Therefore,it is particularly important to study the effect of end face fluctuation on the performance of hydrostatic thrust bearing.Aiming at the problem of end face fluctuation of hydrostatic thrust bearing,the paper starts with the dominant harmonic of the fundamental frequency harmonics,and incorporates it into the clearance change equation of the oil seal surface.By constructing the thrust bearing end face model,the variation of the gap between the sealing surfaces is simulated.The finite difference method was used to solve the Reynolds equation in the polar coordinate system.The pressure distribution on the seal surface was obtained.The characteristics of the static pressure thrust bearing,which is influenced by the periodicity,amplitude and phase of the fundamental wave,the thickness of the oil film,and the number of static pressure chambers,were analyzed and discussed.The specific work is as follows:Firstly,the model of the hydrostatic thrust bearing under the influence of end face wave is established,the structural parameters of the bearing are determined.The Reynolds equation in the cylindrical coordinate system including the centrifugal inertia force is derived,and the calculation formula of the oil film gap function is established according to the model of the thrust bearing.Secondly,the numerical analysis and calculation of the hydrostatic thrust bearing model under the influence of end wave are carried out.The Reynolds equation and the continuous equation in the flow are considered,and the finite difference method is used to solve it.The mathematical expressions of pressure distribution of the cover surface of the thrust bearing and the pressure of the static pressure cavity are derived.On this basis,the calculation is calculated by using the MATLAB finite difference program.Then,a series of formulas for static characteristic of static pressure thrust bearing are derived,and the concept of dynamic pressure ratio coefficient is put forward and its calculation method is explained and deduced.Using self-programmed finite-difference method,the parameters of end-face fluctuations and operating parameters were transformed to obtain the effects of different rotation speeds,oil film thickness,numbers of static pressure chambers,end-face fluctuation period,surface amplitude,and static pressure chamber phase angle.And the static influence of different parameters on the thrust bearing is analyzed.Lastly,the unsteady motion Reynolds equation and the stiffness and damping calculation formula of the bearing are deri-ved.The influence of the parameters of the face surface fluctuation on the stiffness and the damping coefficient was analyzed,such as different speeds,oil film thickness,number of static pressure chambers and end-face fluctuation cycles,surface amplitude,phase angle,etc.The influence of end face fluctuation on the performance of hydrostatic thrust bearing is analyzed in this paper,which has a certain reference value for precision machining. |
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