Research On Mechanism Of Ultrasound En-Hancing And The Experiment Based On Softness Abrasive Flow

Soft Abrasive Flow Machining (SAFM) is a method that cut the Machined parts on the surface by using the mixture of turbulence. However, this approach has some shortcomings: the flow pressure distribution and the Turbulence kinetic energy in the Processing flow runner are to be uneven; processing time is quite longer and its Efficiency is not so high at a time. Proposing a new method that applyment of the ultrasonic excitation technology to the sol-id-liquid two-phase soft abrasive flow machining. This method can enhance turbulence through disturbance flow field, so as to improve the processing, realize the optimization of the soft abrasive flow precision machining. The main conclusions are described as follows:(1) Aimed to the difference between the standard k-ε model and the k-ε two eq-uation model. The latter have some benefits in reflecting the characteristics of jet flow, free flow and the flow in complex passage Analyzed the flowing features of SAP in near wall area, and dissipation rate equation of realizable k-s model is modified based on the analyzing results; the new model can reflect the turbulence dissipation which caused by the finishing in the near wall area previously, It is capable of fully describing the turbulent kinetic energy and pressure in the soft Abrasive Flow.(2) On the basis of the SAFM loading the ultrasonic excitation, As the complex condi-tion of the flow rate in the SAFM, the impact for the ultrasonic excitation can be simplified to the coupling model based on the k-ε two-equations model and Navier-Stokes equations. Analyzing the inflection of the loaded ultrasonic excitation,and the appropriate simulation model is designed.(3) Aimed at the special condition of SAFM loading ultrasonic excitation. Based on the coupling model. Make use of the UDF Function to modify the ultrasonic excitation to solved the flow dynamics equations Analyze the dififience about the fluid pressure, velocity and turbulent kinetic energy distribution on unsteady loading ultrasonic flow channel at different times Through simulation. The results show that ultrasonic excitation have the affection in the Perturbations of turbulent flow. And it changed the kinetic energy, it lay the theoretical basis.For the next step on the soft abrasive flow ultrasound enhanced observing experiments.(4) Aimed to the case of unclear picture in the simulation, make use of the Digital Image Processing Toolbox to process the pictures,at the same time, it need to be morphed with the Bwmorph function, the processing is the Further evidence of the ultrasonic excitation for soft abrasive flow turbulence.(5) Based on the above conclusion of numerical simulation and image processing, take part sic, water mixed solution as a soft abrasive flow machining solution, the soft abrasive flow and transparent flow were observed through the PIV speed camera. It can gain cavitation loaded ultrasonic in the flow channel cavitation, then go on the further analysis using regional to get velocity vectors, vorticity distribution and other information in the whole observation area, and proved that ultrasonic excitation have the siginificant influence for SAFM.(6) Based on the simuliation and the PIV Experiment. Completed the experiment study by putting up the experimental platform for soft abrasive SAFM and design the ultrasonic excitation load constraint module. Machining experiments show that this method can indeed achieve improved processing efficiency and quality, restrain SAFM’s over-processing in high efficient processing area and eliminate dead angle appears, meanwhile, proved the validity of the above simulation method.