Research On Position Control Technology Of Ultrasonic Assisted Double Nozzle Baffle Valve Pressing

The double-nozzle flapper valve is often used as a pilot valve in a multi-stage servo valve,in which the initial gap size accuracy requirement of the nozzle-baffle is extremely high.In actual production,the manual press-fit method is still adopted,which has low work efficiency and poor accuracy consistency.In this work.the ultrasonic-assisted method is used to study the nozzle press-position control technology to improve the press-fit efficiency and realize the automatic press-fit of the nozzleFirstly,a simplified model of the flow field in the nozzle cavity is established to analyze the nozzle cavity pressure characteristics,and the relationship between the nozzle cavity oil pressure and the nozzle-baffle gap size is fitted.The influence of key structural parameters such as oil source pressure,nozzle front-end flow channel roundness error,coaxiality error,dimensional error,surface roughness and nozzle cavity diameter on nozzle cavity pressure characteristics is analyzed by control variable method and orthogonal test method.Then,the nozzle cavity pressure control accuracy index is transformed into the nozzle displacement feed accuracy index,which lays a foundation for the nozzle press position control accuracy analysis.Then,the influence of ultrasonic vibration on nozzle displacement feed accuracy is analyzed,and the mathematical model of ordinary press-fit and ultrasonic-assisted press-fit is established.The feasibility of ultrasonic-assisted press-fit is analyzed from two aspects: ultrasonic friction reduction effect and ultrasonic-assisted elastic release.The finite element simulation analysis of the crawling state and displacement feed precision during the nozzle press-fitting process is carried out.The correctness of the mathematical model is verified by comparing the normal pressfit and ultrasonic-assisted press-fit results.The effect of ultrasonic vibration parameters on the creep phenomenon is analyzed.The control parameters of ultrasonic-assisted press-fit is obtained by investigate the influence of size error,shape error,machining error and assembly error on the press-fit force in the press-fit processFinally,build the ultrasonic assisted nozzle press equipment,program an automatic press-fit control algorithm,calibrate the displacement sensor,and test the system accuracy.Through the comparison test of multiple sets of nozzles,it is verified that the press-fit equipment meets the requirements of nozzle position control accuracy.