The Static And Dynamic Characteristics Analysis Of Hydrostatic Guidewayand Its Damping Identification

The performance of precision CNC machine tool reflects each country's technical strength and the development level of the equipment manufacturing industry,which have been paid much attention by each national industry.For the hydrostatic guide-way having many advantages such as low friction,high stiffness and high precision,it is widely used as the supporting part of CNC machine tool feed system.its static and dynamic characteristics is the key to ensure the accuracy of relative motion between the moving parts of the whole machine performance.This topic use the hydrostatic guide-way as the research object,dedicated to the study,static and dynamic characteristics of hydrostatic guide-way and damping identification.In this thesis we set up a mathematical model which describes the motion state of closed hydrostatic guide-way with quantitative oil in the load direction,the dynamic equation of guide rail sliding table is deduced,studied the dynamic performance of guide under the step load and sine load,listed the guide-way dynamic performance indicators--adjust time Ts,damping ratio ?,dynamic stiffness j,and analyses the effect of the oil viscosity,initial oil film thickness and oil sealing design parameters such as size and quality of guide.Studies have shown that transition time of the guide under the step load increased with the increase of initial oil film thickness,decreases first with the increase of the oil viscosity and then decrease slowly;the dynamic stiffness of the guide-way increase with the increase of loading frequency,decreases with the oil viscosity decreased,decreases with the increase of the oil film thickness.Adopt the method of computational fluid dynamics to simulation oil chamber internal flow field characteristics,a single oil cavity flow field model is established,through the numerical simulation obtained the oil chamber internal flow field distribution and pressure distribution,researched the bearing capacity and stiffness of the single oil cavity,and by changing the single parameter of numerical simulation to study the effect cause by the oil viscosity-temperature characteristics,sealing edge size and the inlet flow on the bearing capacity and stiffness of the oil chamber.The static stiffness of the hydrostatic guide-way experiment and modal experiment is finished,and identified the damping of vertical direction of guiding surfaces and feed direction,compared the acceleration response curve in the feed direction under oil and no oil,Experimental results show that the damping in the feed direction under the condition of no oil is higher than the condition of oil,the vibration resist ability of hydrostatic guide-way in the direction of feed is weaker than the condition of no oil.