Study On Grinding Mechanism And Surface Generation In Ultrasonic Vibration-assisted Grinding Of High Strength Gear Steel

Ultrasonic vibration assisted grinding(ultrasonic assisted grinding)has an obvious improvement on the grinding performance and quality.It has been widely used for the difficult-to-process metal materials such as high-strength gear steel and titanium alloy.However,the grinding mechanism with ultrasonic vibration assistance has not been fully revealed.Therefore,the research on the mechanism of ultrasonic assisted grinding is the important issue.Fatigue-resistant gear design and manufacturing,with tooth surface topography and residual stress as the main control objects,is the frontier of gear research.Among them.the surface generation of gear tooth with high accuracy is one of the key issues.This paper focus on the two main problems of ultrasonic assisted grinding: grinding mechanism and surface generation.The object of material is high-strength gear steel.Besides,two fundamental gear grinding technology is further studied.The main research content and highlights are as follows:1)This paper reported a new understand of ploughing behavior in the ultrasonic assisted grinding with single grain.Based on the analysis of instantaneous contact behavior,the overlap interface of grain-workpiece is calculated and the phenomenon of special contact state in the ultrasonic assisted scratch process is founded.Besides a model for the ploughing friction coefficient is developed and verified by the experiment.2)A prediction model of ground surface topography is established considering the material accumulation due to ploughing effect.The grinding wheel surface is generated based on the real measured wheel surface.And the instantaneous undeformed chip thickness with the ploughing effect and irregular grain shape.Based on the material removal mechanism the ground surface topography is generated.3)A surface generation model of ultrasonic assisted grinding considering Poisson effect is presented.Firstly,the kinematic characteristics of ultrasonic assisted grinding with imposed and additional vibration is analyzed.Secondly,the distribution of undeformed chip thickness and the number of dynamic effective grain is calculated and used to evaluate the surface generation process.Finally,the surface texture control method for ultrasonic assisted grinding considering the interference behavior of continuous wheel rotation cycle is proposed.4)A calculation model of continuous generation gear grinding is proposed.In this process,the complex kinematic relationship and geometric shapes of wheel-workpiece is analyzed.And an algorithm is used to overcome the calculation problem of intersection between cutting path and workpiece surface.5)A calculation model of gear profile grinding is proposed.In the process,the random grain distribution with complex wheel shape is proposed.Besides,the material removal and superposition mode in the process of grain-workpiece interference are analyzed in different local positions along the tooth profileThis paper focuses on the two main problems of ultrasonic vibration grinding: grinding mechanism and surface topography generation of highstrength gear steel.The grinding force reduction and surface generation mechanism under the influence of ultrasonic vibration is revealed.Besides,the three-dimensional tooth surface topography of gear with high precision is developed.The work of this paper provides some new understanding for the fatigue-resistant gear design and manufacturing.