Research On Double-frequency Ultrasonic Vibration Abrasive Flow Polishing Technology For Titanium-tantalum Alloy

Biomedical titanium-tantalum alloy surface micro and nano dual structure in clinical medicine has excellent performance,in order to solve the problem of micro and nano manufacturing of biomedical titanium-tantalum alloy surface leads to the research content of this paper dual frequency ultrasonic vibration abrasive flow polishing.Ultrasonic vibration-assisted abrasive flow polishing is a composite polishing technology that combines traditional abrasive flow polishing and ultrasonic vibration in one.During ultrasonic polishing process,the flow field of the suspension in the abrasive appears turbulent,and the abrasive particles are affected by the flow field and vacuoles and other factors to occur complex kinetic behavior.The material removal is achieved by the grinding action of the abrasive,so it is necessary to analyze the motion characteristics of the abrasive flow field under ultrasonic conditions.Based on ultrasonic vibration theory,this thesis is a theoretical exploration of ultrasonic vibration abrasive processing mechanism and material removal mechanism,and the main research contents and conclusions are as follows.(1)Based on computational fluid dynamics(CFD),the abrasive flow field was simulated under the condition of dual-frequency ultrasonic resonance,and the variation of pressure,velocity vector and abrasive motion trajectory in the flow field in time and space were analyzed,so as to predict the mechanism of abrasive grinding on the material surface.The study showed that: the pressure of the abrasive flow field changes with the change of ultrasonic resonance period,and there is a large amplitude pressure difference between the pressure in the ultrasonic tool head area and the boundary area inside the flow field and it is easier to produce cavitation effect;when the tool head moves downward,the abrasive flow flows to both sides of the tool head,while when the tool head moves upward,its motion trend is opposite,and the reciprocating motion of the abrasive flow will cause turbulence to form near the tool head;the abrasive impacts The specimen has a certain incidence angle,and the incidence angle of the abrasive in the middle region of the flow field is very small,which can be approximated as vertical impact,and the incidence angle in the peripheral region increases gradually,the vertical velocity decreases gradually,the tangential velocity increases gradually,and the abrasive shear effect is strengthened;the kinetic energy of the abrasive decreases with the increase of the processing distance.(2)The impact experiment of micro abrasive particles under dual-frequency ultrasonic excitation was designed to examine the abrasive motion law and grinding mechanism by using the surface morphological characteristics of the experimental material,and the effects of different factors on the significance of the experimental indexes were investigated by means of polar difference and ANOVA.The analysis showed that: the strength of abrasive grinding material was greater than the cavitation effect,and the spot-like pits produced by the cavitation jet acting on the surface of the experimental material,while the abrasive grains would produce qualitatively dense point-like micro-pits;the processing distance played a major role in the maximum micro-pit depth and surface roughness of the experimental material surface,and its polar difference and variance were much greater than those of other factors,and the abrasive impact effect continuously weakened with increasing distance;the optimal parameters of the dual-frequency ultrasonic excitation abrasive flow test were analyzed,and the optimal parameters were obtained at the processing distance.The optimal parameters of the dual-frequency ultrasonic excited abrasive flow test were analyzed,and it was concluded that the polishing efficiency was higher and the surface quality of the specimen was better under the conditions of processing distance of 1 mm,Si C abrasive particle size of 5 μm,dual-frequency angle of 15°,and processing time of 180 s.The conclusion was basically consistent with the simulation prediction.