| The magnetorheological jet composite finishing technology combines the advantages of the magnetorheological technology and the water jet technology,and has unique advantages for the machining of parts with high steepness and complex profiles.In the magnetorheological jet composite processing technology,the stability of the jet beam is an important factor affecting the processing quality and processing efficiency.In this paper,the jet stability,workpiece surface flow field and material removal of the magnetorheological jet composite process are analyzed and simulated,and verified by experiments.The details are as follows:Firstly,the three main factors affecting the stability of the jet are determined according to the dynamic equation.The multiphase flow model in the COMSOL simulation software is used to analyze the interface between the jet and the air after being ejected from the nozzle.By comparing the changes of the beam diameter of the jet,the effects of the three factors of different volume fractions of carbonyl iron powder,different jet velocities and different magnetic field strengths on the jet stability are studied.After that,the k-? flow model suitable for magnetorheological jet is selected according to the abrasive jet impact theory,and Fluent finite element simulation software is used to analyze the flow field distribution(i.e.,the velocity distribution and pressure distribution on the surface of the workpiece)when it hits the workpiece surface under normal incidence and 60-degree angle incidence.According to the flow field distribution,the material removal mechanism on the workpiece surface is discussed,and the material removal shape is analyzed by the normalized flow field distribution.The theoretical material removal at different speeds is calculated using the material removal formula.Finally,the experiments are carried out using the built-up magnetorheological jet finishing experimental device.Three experiments are implemented.First,the effects of different volume fractions of carbonyl iron powder,different jet velocities and different intensity of magnetic field on the stability of magnetorheological jet beams are tested.By comparing the changes of the beam diameter from the three locations of the jet beam which are at the beginning,the middle and the end,the influence of each parameter on the stability of the magnetorheological jet is verified;Second,the magnetorheological jet finishing workpiece of 45# steel is carried out to verify the shape of the workpiece surface material removal by observing the workpiece surface before and after processing via of the metallographic microscope;The third experiment is to use the magnetorheological jet,the workpiece is processed under different jet speeds for 20 minutes each,and the quality changes before and after processing are measured to verify the influence of the jet speed on the theoretical material removal by measuring the quality changes of workpiece before and after the magnetorheological jet finishing workpiece of 45# steel. |
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