The Design And Analysis Of Thin Film Restrictor Of Active Control Hydrostatic Bearing

For its characteristics of small friction coefficient,excellent load capacity,high rigidity,stable operation,long service life,hydrostatic bearing is widely used in all kinds of heavy equipment,and has become the core component of heavy machine tools.Restrictor is one of the key component of hydrostatic bearing,determines whether the hydrostatic bearing operate well,it plays an important role for the accuracy and load of hydrostatic bearing.However,the traditional fixed restrictor and changeable restrictor can't adjust actively in application,so they have no accurate control for the position of spindle.In order to achieve high precision,this paper put forward an active control restrictor,it can control the throttle clearance to change the support state of spindle,according the demand of hydrostatic bearing.On the one hand,spindle no move with the change of external load,which means hydrostatic bearing has infinite stiffness.On the other hand,spindle can move actively to meet micro feed at the same time.The main research contents are as follows:1.Take four oil cavities hydrostatic bearing with constant oil flow as an example in this article,analyze the working principle and the theory of fluid lubrication,and conduct the Reynolds equation of hydrostatic bearing oil film,then mesh the Reynolds equation by the use of finite difference method.Finally,cavity pressure?flow and capacity of the capillary restrictor hydrostatic bearing and film restrictor hydrostatic bearing are calculated with the application of MATLAB.2.Propose the use of piezoelectric ceramics on thin film restrictor,two control schemes are designed: the piezoelectric bimorph film restrictor and the piezoelectric stack film restrictor,discuss hydrostatic bearing with the piezoelectric bimorph film restrictor and the piezoelectric stack film restrictor.Finally,chose the piezoelectric stack film restrictor as the feasible scheme.Design the structure model of the piezoelectric stack film restrictor,get the relation between force and displacement and the voltage of the piezoelectric ceramic actuator.3.Solve the control relationship of piezoelectric stacked thin film restrictor by use of FLUENT,the fluid solid coupling method is used to analyze the deformationof the piezoelectric stack thin film restrictor with the oil pressure and piezoelectric ceramic actuator.The relationships including voltage and displacement of the film displacement,film displacement and oil pressure,oil the cavity pressure and loads,are obtained,finally,get the relationship between loads and voltage.In addition,make a study of the factors that may affect the control relationship,such as frequency,throttle size etc.4.Set up the control model of ordinary thin film restrictor and piezoelectric stack thin film restrictor,then simulate the dynamic simulation of the two systems individually,obtain the system dynamic response curves,finally get the eccentric displacement and the response time of the spindle under different load.Make a comparison of two dynamic response,prove the superiority control of piezoelectric stacked thin film restrictor.