Research On The Design And Key Technology Of Magnetorheological Polishing Device With A Small Polishing Head

In recent years,with the wide application of high-performance optical element in the field of national defence and military industry,aerospace,nuclear power,medical detection,photography,etc.,the market demand for minor-caliber concave structure optical components continues to grow,and the requirements for its quality and performance are also increasing.The common forming process will inevitably leave machining marks and surface defects on the workpiece surface which lead to poor accuracy,and narrow processing space of minor-caliber concave structure,special properties of hard and brittle materials,high requirements of surface quality will also bring great difficulties to subsequent polishing processing.For the above problems,this paper proposed a magnetorheological polishing(MRP)device with a small polishing head to overcome the shortcomings of traditional wheel type MRP device which is difficult to adapt to minor-caliber concave structure,to expand the processing range of MRP technology,and to achieve high efficiency and surface quality.The main contents of this paper are as follows:Firstly,according to the characteristics of the workpiece and the technological requirements,a small polishing head MRP device was developed,and the excitation part of the polishing head was designed in detail and analyzed by the finite element method.The rheological property of MRP polishing fluid was studied,and the rheological property equation based on Bingham model was derived.On this basis,the multi-physical field coupling simulation analysis of MRP renewal unit was carried out.Furthermore,the paper analyzed the difference between the small polishing head and the traditional wheel device,and further analyzed the removal mechanism of MRP from the forces acted on the single abrasive and the effect on the material.It is considered thatthe positive pressure of the polishing fluid on the abrasive makes it press into the workpiece surface,while the tangential force provides the shear force for material removal.On this basis,the material removal model of workpiece surface was established,and the mathematical model of workpiece surface roughness was further deduced.According to the experimental data verification,in a certain range,the model error was within 10%,which can partly explain the actual processing situation.Finally,experiments were carried out by response surface method,and the influence of main process parameters(polishing head speed,polishing gap,polishing time)on the reduction percentage of roughness Ra(%?Ra)and the material removal rate were analyzed.The multi-objective genetic algorithm was used to optimize the process parameters of Ra%?and the removal rate.Compared with the middle level of each factor,the removal rate was improved by %6.7 and %?Ra was improved by 17.2%.