The Impact Action Study Of The Cavitation Bubble Collapsing To A Rigid Boundary In Ultrasonic Honing

Cavitation bubble existed near a rigid boundary in ultrasonic honing can produce high-temperature and high-pressure cavitation erosion.effect on the rigid boundary,after a series of expanding contracting and collapsing bubble wall motion.cavitation erosion effect of the rigid boundary is mainly effected by the shock wave and micro jet generated in the process of cavitation bubble breaking.The deformation of a rigid boundary material is also effected certainly by the cavitation bubble breaking pressure field.This paper took cavitation bubble produced from grinding fluid in ultrasonic honing as the research object,applying the theories including cavitation bubble dynamics,shock wave propagation theory of interfaces and material failure criterion,to analyse the impact of the cavitation bubble breaking pressure field and its shock wave from ultrasonic honing parameters and cavitation bubble initial radius and calculate the threshold of the shock wave and micro jet required for material failure.Finally,the cavitation degree changes of the surface material of the workpiece under different conditions was studied by ultrasonic vibration experiment.It provides a theoretical and experimental basis for the further research that the impact action produced by the cavitation bubble collapsing in ultrasonic honing act on rigid boundary.The main work and conclusions of this paper are as follows:(1)The finite element model of the thermal-mechanical coupling single abrasive grinding of ultrasonic honing has been established.The simulation results showed that the abrasive edge chip under a certain grinding depth had plastic removal,when the abrasive edge radius was 0.1 ?m and 10 ?m about,which was promoted by the grinding heat effect.However,when the abrasive edge radius was 0.1 ?m about,abrasive edge chip almost had happened no phenomena of plastic flow,the grinding heat effect was unapparent either.(2)Under environment pressure in the ultrasonic honing gringing area,the mathematical model of the distribution of pressure field outside a bubble was deduced when it was collapsing,and the influence of the cavitation bubble volume ratio for the maximum pressure value and its position.Obtained by analysis: The effect of cavitation bubble collapsing pressure field in ultrasonic honing grinding area for the most metal materials surface belong to the elastic deformation which does not influence directly the cavitation erosion effect to a rigid boundary.(3)cavitation bubble produced from grinding fluid in ultrasonic honing was considered as the research object,considering the liquid surface tension,deducing the theoretical model of cavitation bubble maximum radius,calculating that the maximum value of the cavitation bubble maximum radius is obtained when the normalized time is 0.751.The value increases with the sound pressure amplitude and the initial radius of cavitation bubble increaseing,and decreases with the increase of honing pressure.The smaller the cavitation bubble of initial radius was,the greater the magnification of cavitation bubble maximum radius related to its initial radius was.(4)Cavitation bubble's energetic model in ultrasonic honing grinding area was derived in theory,and the effect of acoustic pressure amplitude,honing pressure and cavitation bubble initial radius to the cavitation bubble' energy in the three characteristics of one ultrasonic vibration cycle time.The results showed: cavitation bubble' energy can achieve maximum value influenced respectively by the above three parameters around 0.249 of the normalized time.The initial cavitation bubble radius plays a decisive role in the change of cavitation bubble's energy relative to the acoustic pressure amplitude and honing pressure.Combining with the relationship between the explosion energy and the propagation velocity and pressure of the shock wave given by the strong explosion theory,the same effect trend that the cavitation bubble collapsing shock wave and the cavitation bubble's energy is influenced by the above three parameters was obtained when other conditions were constant,and the effect that the initial radius of the cavitation bubble influence its shock wave was the largest correspondingly.(5)When theoretical calculation for the strength of the cavitation bubble collapsing shock wave arrived at a rigid boundary was greater than 203.77 MPa,the rigid boundary materials 2024 Al would occur plastic deformation;for the same situation,the micro jet speed arrived at a rigid boundary was greater than 262.59m/s.(6)Building the cavitation erosion experiment platform of ultrasonic vibration near a rigid boundary,some results given: with the increase of experimental time,the roughness and Vickers hardness on the workpiece surface were increasing.And after a certain respectively rapid growth,its would go into the slowly increasing stage at different time points.With the increase of the ultrasonic amplitude,the roughness and vickers hardness on the workpiece surface rapidly increased first,then turned to slow growth stage when the ultrasonic amplitude was 10.8 ?m about.With the increase of the experimental solution viscosity,roughness on the workpiece surface basicly showed a trend of decrease,and the values of the roughness and vickers hardness on the workpiece surface before and after the experiment has certain positive correlation.The impact experiment of the cavitation bubble collapse acting on the rigid boundary in ultrasonic vibration has a certain guiding significance for the part of a shock effect that was produced from the cavitation bubble collapse acting on the rigid boundary in the ultrasonic honing gringing area.