Research On Low Friction Cylinder Based On High Frequency Vibration Of Piston Rod Sleeve And Its Trajectory Tracking

Pneumatic technology has been widely used in food processing,medical equipment,aerospace,automobile installation and processing industry,because of its advantages of clean and pollution-free,low maintenance cost and high safety performance.However,due to the compressibility,low damping,low stiffness and other non-linear factors of the gas,the cylinder in the process of low-speed motion will be unstable,and the control accuracy will be reduced.Therefore,improving the motion accuracy of the cylinder is of great significance to the application of the propulsion pneumatic system,in this paper,vibration friction reduction technology is applied to the cylinder,and a low friction cylinder based on vibration friction reduction effect is designed to improve the motion accuracy of the cylinder by improving the friction characteristics of the cylinder.Friction is the key factor affecting the motion accuracy of the cylinder.In order to explore the friction characteristics of the cylinder under different vibration modes,the longitudinal vibration,transverse vibration and the friction force models at any angle in the longitudinal vibration and transverse vibration plane are established based on Dahl friction model.The key factors of reducing friction effect are analyzed by numerical simulation,and the results show that:for the above three vibration modes,with the increase of the ratio of the vibration speed of the sealing ring to the sliding speed of the piston,the effect of vibration friction reduction is enhanced.For longitudinal vibration,the vibration friction reduction phenomenon only appears when the ratio of the vibration speed of the sealing ring to the sliding speed of the piston is greater than 1;For transverse vibration,when the vibrationsliding speed ratio is less than 1,the friction reduction effect is better than longitudinal vibration,and when the vibration-sliding speed ratio is greater than 1,the friction reduction effect is less than longitudinal vibration;For the vibration at any angle in the plane of the longitudinal vibration and the transverse vibration,the friction reduction effect is between the longitudinal vibration and the transverse vibration,when the vibration-sliding speed ratio is less than 1,the friction reduction effect becomes better with the increase of the angle between the vibration and the piston movement direction,it becomes opposite when the vibration-sliding speed ratio is greater than 1.A low friction cylinder based on vibration friction reduction effect is designed,and the vibration response of the cylinder under different resonance frequencies is studied by modal analysis and harmonic response analysis,which verifies the rationality and feasibility of the low friction cylinder structure.Through the processing of the corresponding parts,the vibration friction reduction cylinder prototype was set up,and the actual resonance frequency was measured by impedance analyzer,and the friction test under each vibration mode was carried out,the results show that the first-order longitudinal vibration has the best friction reduction effect,which can reduce the dynamic friction by 33.8%,followed by the secondorder longitudinal vibration,which can reduce the dynamic friction by 10%.In order to verify that the vibration friction reduction cylinder can improve the motion accuracy of the cylinder,the PID control algorithm is used to research the trajectory tracking control,the results show that the maximum motion accuracy of the cylinder can be improved by about 19% under the vibration condition,but compared with the original cylinder,the motion accuracy is reduced when there is without vibration,after analyzing the reasons,the piston rod parts of the vibration friction reduction cylinder are improved,and the motion accuracy of the cylinder is improved to 1.7mm under the without vibration condition,under the condition of vibration,the motion accuracy is improved to 1.35 mm,and the motion accuracy is improved by about 21%.Finally,through the control of the signal generator,the vibration friction reduction is realized only at the two ends of the cylinder stroke,which can ensure the improvement of the cylinder motion accuracy and reduce the power consumption and noise generation.