| The hydrostatic support guide-way has many advantages such as high precision,small friction coefficient and good stability,and is widely used in large and heavy machine tools as well as precision machine tools.The labyrinth seal is a non-contact seal structure with simple structure,convenient maintenance and reliable performance.It is mainly used in rotating machinery such as centrifugal pumps,steam turbines and aero engines.In order to improve the machining accuracy and stability of the hydrostatic support system and ensure the machining quality of the machine tool,the structural innovation of the oil chamber is carried out.The characteristics of straight-through labyrinth seal and its influence on the static and dynamic characteristics of hydrostatic support guide-way are studied.The research content of this paper is mainly composed of the following four parts:(1)Detailed analysis of the working principle of the hydrostatic support system and the straight-through labyrinth seal.In order to improve the static and dynamic performance of the hydrostatic support guide-way,combined with its working principle and common characteristics,the scheme of applying straight-through labyrinth seal on the oil seal side of the oil chamber is proposed without changing the geometric parameters of bearing surface of the hydrostatic oil chamber.(2)This paper analyzes the main factors that affect the oil leakage of straight labyrinth seal.The internal flow field of labyrinth seal is simulated by CFD method.The Fluent solver is solved by the Realizable k-? turbulence model,and the static pressure distribution of the oil film and the flow velocity distribution of the lubricating oil flow field are obtained.The labyrinth seals with different clearance width(oil film thickness),number of grooves(cavity number),depth of grooves(cavity depth)and pressure difference are simulated,and the data obtained are compared and analyzed.The results show that the clearance width,the number of grooves and the geometry structure size of the groove have an important influence on the performance of the straight-through labyrinth seal.(3)Based on the three-control body theory,referring to the establishment process of governing equations for circumferentially-grooved liquid seals,the analysis and solution method of the straight-through labyrinth seal in the plane direction of the oil chamber are derived.The governing equations that characterize the seal flow characteristics are established and derived,and the dimensionless parameters are defined and the equations are dimensionless.The perturbation method is used to solve the governing equation,and the steady flow field is obtained from the zero-order dimensionless equation,and then the first-order dimensionless equation is solved.The numerical results are compared with the Fluent simulation results to verify the reliability and accuracy of the established model,which provides a theoretical basis for the numerical solution of the planar straight-through labyrinth seal.(4)The application of straight-through labyrinth seal on oil sealing belt of oil chamber will have an impact on the overall static and dynamic performance of the hydrostatic guide-way.Starting from the static and dynamic equations of the closed hydrostatic guide-way,the bearing capacity,static stiffness and power loss of the hydrostatic guide-way are taken as its static performance indexes,and the natural frequency,adjustment time and dynamic stiffness are taken as its dynamic performance indexes.The influence of the design parameters such as the width of the oil sealing belt,the thickness of the oil film and the viscosity of the oil on the hydrostatic guide-way rail is studied.The straight labyrinth seal is creatively applied to the oil sealing belt of the hydrostatic support oil chamber,which expands the application range of the labyrinth seal,improves the static and dynamic performance of the hydrostatic support systerm,and has high practical value. |
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