| Frequency response characteristics of hydraulic cylinder is mainly limited to friction characteristics of elastic ring,friction is inversely proportional to the sealed interface distance,which makes the friction and leakage become a pair of violent conflicts,and the conflicts are the main factors to testrict the hydraulic cylinder frequency response performance.Servo hydraulic cylinder is the control center and key equipment of high-power and high precision automation equipment in the hydraulic servo system.How to develop the traditional equipment in the direction of advanced and green energy saving,become the basis for the survival and the key point to sustainable development of future manufacturing.So higher requirements are put forward in the frequency response performance and service life of servo hydraulic cylinder.In order to achieve good friction performance of hydraulic cylinders,texture is designed on the gas-liquid phase lubricating surface,a dynamic pressure lubrication support force model was established based on gas coupled liquid film.Calculating the cavitation lubrication characteristics and extending the model to which can solve the compressible film LCP equation coupling the cavitation and wedge effect,the neural network and the algorithm is applied to design the optimal grid parameters.The texture is applied to the hydraulic cylinder surface,the texture effects on the leakage is studied,the lubrication characteristics can optimized the conflicts between the drag reduction and the leakage,the reasearch provides a theoretical and technical foundation for the realization of the new high speed servo hydraulic cylinder.1 Hydrodynamic lubrication surface texture design and numerical solution.In order to study the friction characteristics of surface texture under different morphology conditions,first the different morphologies numerically equations were solved based on the traditional Reynolds equation.After comparing the Sommerfeld boundary condition and the semi-Sommerfeld boundary condition,finally the Reynolds boundary condition is applied.Five points difference method is used to solve the numerical solution,then the composite trapezoidal formula is used to solve by integral the pressure,and the required tribology properties is obtained.This mathematical model studied surpport force,friction and coefficient of friction under different texture shape and the arrangement.2 Numerical compensation LCP model for surface texture cavitation effect.The traditional Reynolds equation does not consider the formation of cavitation in surface lubrication,and it cannot explain the evolution of oil film accurately.In this paper,the linearly compensated LCP model based on improved pressure and variable density is deduced.It can accurately predict the friction performance and steam volume fraction link with the gas-liquid two-phase CFD simulation.Reasonable cavitation effect is beneficial to obtain good promoting effect on the lubrication and to reduce the friction between the friction pairs,thereby improving the oil film support.3 Study on the compressible two-dimensional LCP model with wedge coupling cavitation effect.The above cavitation model is considered as incompressible fluid,but in the actual working conditions,due to the errors of manufacture and assembly in hydraulic cylinder and the impact of the load,there is a certain angle between the relative friction pairs,so the oil film need to consider the extrusion effect in addition to dynamic pressure support,the squeezing effect need to be considered,extended the one-dimensional LCP equation of cavitation effect to two-dimension compressible LCP equation of wedge coupled cavitation effect,analyzed the condition that the piston friction is not parallel,studied the microscopic characteristics of the wedge film and its tribological properties.4 Comparative analysis of the textured surfaces friction properties.The texture parameters and morphology have important effects on the surface lubrication characteristics,and the friction coefficient can be greatly reduced by rationally designing the texture size.In order to obtain the ideal texture parameters,the surface response analysis and mixed BP-GA neural network method was used to screen and optimize the friction characteristics under the surface cavitation condition and to establish the prediction between the texture parameters and the lubrication model.Finally,the prediction and optimization results of the two methods are validated by experimental data.The hybrid BP-GA neural network can accurately check the friction performance under different texture parameters.5 Experimental study on texture leakage and friction in hydraulic cylinder.Texture was processed on the inner wall of the hydraulic cylinder,respectively tested the traditional sealing ring piston and the new types of seal clearance type piston,through the cross-test of two kinds of pistons and two kinds of cylinder,it can be concluded that: tests under two kinds of pistons,the textured cylinder friction coefficient can effectively reduce;the variable clearance seal hydraulic cylinder friction coefficient is less than the traditional lubricant,the variable clearance seal hydraulic cylinder has better characteristics,but has large amount of leakage;whether the traditional piston or the new kind piston,the influence of the structural hydraulic cylinder on the leakage volume is stabilize,whereas the friction coefficient has been reduced more than 50%. |
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