Research On The Wear Characteristics Of Interference Fitting Parts During Ultrasonic Assisted Press-fitting

Interference fitting parts are widely used in automotive,electronics,aerospace and other mechanical industries.The quality of connection directly affects the reliability and stability of the equipment.And the interference fitting parts is usually assembled by press-fitting method.Due to the large friction force and wear between the parts,the connection force decreases.In order to reduce the friction and wear and increase the connection force,the application of ultrasonic vibration to the process of the press-mounting is proposed.The wear of the contact parts during ultrasonic press-fitting is mainly studied.Firstly,according to the content of the subject,the research status and friction and wear characteristics of the traditional press-fit assembly and ultrasonic assisted machining are studied.The basic principle of friction and wear,the Archard wear model and the abrasive wear model are also studied.Then,by measuring the temperature of the shaft and sleeve,the effect of ultrasonic softening on the friction and wear process is eliminated.Combined with the analysis of the mechanism of ultrasonic friction reduction and the wear calculation model of traditional press-fit assembly,the wear calculation model of ultrasonic press-fitting is determined.According to the wear calculation model,it is determined that the change of the wear of ultrasonic press-fitting relative to the traditional press-fit assembly on the contact interface is mainly the change of radial stress and tangential stress.The emphasis is the influence of the indenter amplitude on the tangent stress.Based on the Abaqus software,the ultrasonic press-fitting model of interference fitting parts is established.The change rule of radial stress and tangential stress in the traditional press-fit assembly and ultrasonic press-fitting,as well as the influence of the change rule on the wear are analyzed.In order to facilitate the measurement of subsequent experiments,the study of tangential stress is converted to the study of friction.The effects of ultrasonic amplitude,frequency,interference,friction coefficient and press-fitting speed on friction force are analyzed.The simulation results show that the frequency and press-fitting speed have no effect on the friction reduction effect.In general,the factors that cause the increase of friction force will reduce the friction reduction effect,for example,the increase of interference amount and the friction coefficient.When other factors are constant,the friction reduction effect increases with the increase of amplitude.According to the wear calculation formula of ultrasonic press-fitting,the frequency and press-fitting speed have no effect on the wear.The wear increases with the increases of interference amount or friction coefficient.But the wear decreases with the increases of amplitude.The prediction model of ultrasonic friction reduction rate based on neural network is established.And the prediction error is within 6%,which provides a theoretical basis for the calculation of press-mounting force and wear control in ultrasonic press-fitting.Finally,an experimental platform was built to carry out traditional press-fit assembly and ultrasonic press-fitting experiments.The results show that the ultrasonic press-fitting can obviously reduce the friction force,and the smaller the interference amount,the better the antifriction effect.When the interference amount is 14 m,the friction force of the ultrasonic press-fitting can be reduced by 29.12% compared to the traditional press-fitting.It can be deduced that the smaller the interference amount is,the smaller the wear of interference fitting parts during ultrasonic press-fitting.The friction and friction reduction rates obtained by Abaqus finite element simulation are basically consistent with the experimental values.So the finite element model is reasonable.The shaft and sleeve are cut after the press-fitting and the scanning electron microscope is used to observe their contact surfaces.The wear type of the press-fitting process is mainly the plow wear in the abrasive wear,and the wear degr ee of the interference fitting parts of the ultrasonic press-fitting is less than the the traditional press-fitting.And the adhesive wear has also occurred in the process of tradition press-fitting.Finally,the connection force measurement experiment further shows that ultrasonic press-fitting can reduce wear and improve the connection quality of interference fitting parts.