Experimental Research On Sapphire Ultrasonic Vibration Assisted Scratching

Sapphire has been widely used due to its superior mechanical and physical properties.However,the processing of sapphire is difficult,and the processing effect needs to be improved.A large number of studies have shown that ultrasonic vibration-assisted grinding of sapphire can improve processing efficiency and surface quality,but its mechanism still remains to be studied.Therefore,this subject proposes a pendulumtype ultrasonic vibration-assisted scratching device with equal depth of cutting.Using this device,a single-factor variable comparative test test of axial ultrasonic vibrationscratching is performed on a sapphire single crystal.To compare the effects of various parameters on the scratch characteristics with and without ultrasonic vibration,the main contents include:(1)A pendulum-type ultrasonic vibration-assisted scratch device of equal cut depth was built,and a multilayer structure grinding wheel was designed to simplify the operation of the device.The feasibility of verifying the device proved that it is usable for the scratch with equal depth of cutting.(2)From the perspective of kinematics and mechanics,combined with modeling and simulation work,theoretical analysis found that there are periodic changes in displacement,velocity,acceleration,and force when the axial vibration is applied,Under the same conditions,axial ultrasonic vibration-assisted scratching compared to the ordinary scratching has the characteristics of long scratch trajectory,wide scratch groove,and large removal volume.The material removal volume increases with increasing amplitude,decreasing scratch speed,or increasing vibration frequency..(3)A single-factor variable comparative test test for axial ultrasonic vibrationassisted scratching of sapphire was designed.The effects of ultrasonic amplitude,scratch speed,and scratch depth on the C-plane sapphire scratch force,force ratio,and scratch morphology were compared,The axial ultrasonic vibration-assisted scratch force is less than the ordinary scratch force.With the increase of the scratch speed and depth,and the decrease of the ultrasonic amplitude,the force and force ratio of the two scratch methods will increase.With the application of axial ultrasonic vibration,the bottom of the scratch is more densely broken,and crack propagation and spalling mostly occur near the corners of the track.With the increase of the scratch speed,the crack width becomes smaller at the same scratch depth,and the small degree of fragmentation decreases.With the increase of the scratch depth,the degree of crack propagation and fragmentation increase,and massive flaking is likely to occur.(4)The effects of four different sapphire crystals on the scratch force,force ratio,scratch morphology,and surface grinding morphology were compared.The forces of the two scratching methods decrease in the order of C,M,A,and R.Force ratio is decreasing in the order of M,A,C,R.And the morphological differences of the surface after scratching and grinding on different crystal planes were analyzed.It shows that axial ultrasonic vibration assisted grinding can effectively reduce pits and improve surface quality.