Study On The Technology Of Ultrasonic Vibration Assisted Belt Grinding

Ultrasonic vibration assisted belt grinding(UABG)is a new processing technology.Compared with the conventional belt grinding,the advantages of the technology are less grinding force and less grinding heat and high surface quality.In view of the analysis of the relevant literatures in this field,the grinding principle of the UABG is systematically studied.On the basis of the experimental study,trajectory characteristics of the normal UABG are clarified.The grinding force mathematic model of the normal UABG is founded,and the characteristics of grinding force are analyzed.The removal process of single abrasive grit is simulated,and the surface quality of the specimen is verified by experiments.Design ultrasonic amplitude transformer is based on theoretical analysis and finite element,and the amplification test of amplitude shows that the accurate control of the amplitude can be realized by controlling the frequency and power.It is found that the output amplitude reaches the maximum at the resonant frequency,and decreases far from the theoretical resonant frequency,and the output amplitude is proportional to the power.The grinding process of UABG is the cutting process of numerous abrasive grits.According to the kinematic trajectory characteristics of the belt grinding assisted by ultrasonic vibration,the equation of the kinematic trace of single abrasive grit is deduced,and the simulation model of the kinematic trace of single abrasive grit is established.The results show that the grinding path length of single abrasive grit is longer than that of conventional belt grinding,and the grinding path is a sine curve.The number of periodic oscillation of the grinding path is proportional to the frequency and inversely proportional to the grinding speed.The grinding force mathematic model of single abrasive grit is established in conventional belt grinding and UABG.The verification experiment of belt grinding force is designed.The results show that the grinding force of UABG is lower than that of conventional belt grinding.With the increasing of grinding depth and vibration amplitude,the grinding force increases,and with the increasing of spindle speed,the grinding force decreases.Based on the material constitutive model,failure criterion,contact and friction theory,the simulation model of single abrasive grinding is established.The analysis shows that the tangential force and normal force of the single abrasive grinding by ultrasonic vibration are lower than that of conventional belt grinding.Under different grinding parameters,the grinding force of single abrasive grit is consistent with the predicted results of the grinding force mathematical model.With the increasing of grinding depth,grinding speed and vibration amplitude,the grinding temperature increases,and the grinding temperature decreases under the ultrasonic vibration.Comparing the surface quality of ultrasonic assisted abrasive belt grinding with conventional belt grinding,it is founded that the machined surface quality is better than that of conventional belt grinding under the condition of ultrasonic vibration.The surface of the specimen after conventional belt grinding shows parallel and scratched stripe,and stripe depth is inconsistent.Under the ultrasonic vibration assisted belt grinding,the specimen surface shows closely aligned imbricated pattern,and the depth of the pattern is less than that of the common grinding.The surface roughness of the specimen under normal grinding is graded and there are obvious parallel boundaries.Under the condition of ultrasonic vibration assisted belt grinding,the distribution of surface roughness of the specimen is disordered,and there is no obvious boundary condition.The roughness value is lower,and the distribution of high roughness is decreases,with the increasing of the grinding depth,the surface roughness of the specimen increases,and with the increasing of spindle speed,abrasive grit size and vibration amplitude,the surface roughness of the specimen decreases.When the vibration amplitude is too large,the surface roughness will increase.The surface roughness of the machined surface under ultrasonic vibration assisted belt grinding is less than that of the conventional belt grinding.