Dynamics And Collapse Temperature Of Single Cavitation Bubble In The Grinding Area Of Power Ultrasonic Honing

A large number of cavitation bubbles are produced in the grinding area while Power ultrasonic is honing. They expand rapidly and compress to collapse, and high temperature and high pressure also appear in the collapse process. Dynamics and collapse characteristic of single cavitation bubble is necessary to be researched for studying the effect of ultrasonic honing process.The dynamics of single cavitation bubble in the ultrasonic honing was studied, regarding the grinding fluid as the work medium. The motion process of cavitation bubble which is greater than the initial radius is as isothermal process, and which is less than the initial radius is as adiabatic process. Depend on these, the model of single cavitation bubble in the ultrasonic honing area was established in this paper, and used4-5Runge-Kutta method in MATLAB software to calculate, discussed the influence of factors on single cavitations bubble motion. It can be found that, compared with the ordinary ultrasonic cavitation bubble, the cavitation bubble in the grinding area of ultrasonic honing is steadier, but its frequency is rapider and amplitude is smaller. Honing pressure has an obvious influence on cavitation bubble motion, and promotes the process of cavitation bubble to collapse. The influence of rotary speed、reciprocating speed is relatively small. The greater the viscous coefficient of grinding fluid, the smaller amplitude of the cavitation bubble. With the increase of ambient temperature, the smaller cavitation bubble movement becomes more intense, while larger cavitation bubble gradually becomes stable. The influence of sound pressure amplitude on cavitation bubble motion also is obvious. As pa<po+pH cavitation is hard to happen, while pa≥po+pH with the increase of sound pressure amplitude, the amplitude of cavitation bubble can significantly larger, and much easier to crush, cavitation effect is moreobviously.Then the max temperature and pressure formula and calculated the results to singlebubble were established, the influence of various factors on max temperature and the maxpressure were also be analyzed. It shows that, the instantaneous max temperature Tmax andmax pressure Pmax in cavitation bubble in ultrasonic honing grinding area is bigger thannormal ultrasonic cavitation. With the increase of ambient temperature, the gap can begradually decreased. The Tmax、Pmax increases quickly with honing pressure and soundpressure amplitude increasing, while it decreases when ambient temperature increases.Although with the increase of honing head and reciprocating rotary speed the values increase,but the amplitude is small.At last, single cavitation bubble CFD geometric model in the ultrasonic honing area wasestablished to analyze the diffusion process of high temperature which produced in cavitationbubble breaking instant. FLUENT software was used to solve that. Conclusions are as follows:The instantaneous high temperature produced in cavitation bubble will pass to the grindingfluid first, and as it flow the high temperature passed to the workpiece and sharpening stone.The system temperature of the research object will increase1~2K with the diffusion oftemperature. As the grinding fluid flow the high temperature area will change, andinstantaneous high temperature would be produced in the workpiece surface, affecting theultrasonic honing processing.