| Gear transmission is one of the most widely used transmission modes and plays an irreplaceable role in the field of mechanical engineering.In recent years,with the rapid development of industries such as automobiles,high-speed trains,aerospace and construction machinery,we also put forward higher requirements on the performance of gear transmission.However,the performance of gear transmission is closely related to the strength and surface quality of gears.Therefore,studying how to improve gear strength and surface quality will have very important practical significance.The main research content is as follows:Combined with characteristics of ultrasonic extrusion strengthening technology and the formation principle of gear involute,a set of ultrasonic extrusion strengthening device of gear tooth surface is designed to realize the irregular surface strengthening.The finite element software ANS YS Workbench is used to analyze the modal analysis and harmonic response of the horn in the ultrasonic vibration system.The amplification coefficient,resonant frequency,axial displacement distribution curve and the maximum stress and strain distribution curve of the horn are obtained,which can help to determine the amplification and reliability of the horn.The influence of different feed speed,machining times and electric current on the roughness and hardness of tooth surface is studied by orthogonal experiment.The experimental results show that the roughness of the tooth surface is reduced and the hardness of the tooth surface is also improved after ultrasonic extrusion strengthening.Under the experimental conditions of this paper,the influence of feed speed,machining times and electric current on the roughness and hardness of tooth surface are similar.The most influential factor is the feed speed,the second is the electric current,and the influence of repetitive machining times is relatively small.Based on the experimental results,the prediction models of surface roughness and surface microhardness are established.The significance test is conducted by F test.The results show that the regression equation is significant in the 95%confidence interval.In addition,the white light interference surface profilometer is used to test the tooth surface before and after ultrasonic strengthening,which further proves that the ultrasonic strengthening has a certain degree of repair effect on the tooth surface micro-roughness.The finite element simulation of the tooth surface after ultrasonic extrusion strengthening is performed by using ABAQUS/explicit.The stress distribution of the gear tooth surface after strengthening,as well as the influence law of static pressure,feed speed and amplitude on the residual stress of tooth surface is obtained.The results of finite element simulation show that the residual stress is produced on the tooth surface after ultrasonic extrusion strengthening and the static pressure and the feed speed greatly influence the residual stress,but the amplitude has little effect on the residual stress. |
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