Research On Shear Thickening Mechanism And Prescription Of Non-newtonian Polishing Slurry

With the global technological revolution making process and breakthrough,the process performance of precision parts are getting better,the requirements for ultra-precision machining are increasing at the same time;especially for the complex surface,it is difficult to process well.A complex surface is a complex manifold of dimension two,it is a combination of many curvature surfaces;it has been the important working surface in many areas such as aerospace,auto parts,mould,and biomedical implants.With the improvement of performance requirements and increasing demand,the processing requirements need to improve at the same time:on the one hand,better surface quality and accuracy are needed;on the other hand,a processing method of high efficiency and low cost is urgent to put forward.A new polishing method is proposed in this paper though the shear thickening mechanism of slurry;a high efficient and high quality polishing results can be achieved with this polishing method.A high efficiency and low cost polishing method based on the shear thickening mechanism of non-Newtonian slurry is put forward in this paper,and the shear thickening mechanism of non-Newtonian polishing slurry is detailed discussed.Then the material removal model is proposed according to the shear thickening mechanism.For the complexity of shear thickening phenomenon,the shear thickening process is detailed analyzed by rheological curves and mathematical model.According to the constitutive equation of non-Newtonian fluid and hydromechanics,a mechanical model formula is derived which is used for force calculation of workpiece surface,and mechanical analysis on non-Newtonian slurry is researched in this paper.The feasibility of shear thickening method is verified by finite element simulation;the simulation results indicate that shear thickening accurse in the polishing process at the certain conditions.The pressure and velocity contours and trajectory of abrasives are got though analysis of simulation results.Through contrast of simulation results between non-Newtonian slurry and Al2O3/PEG200 slurry,the non-Newtonian slurry is better than Al2O3/PEG200 slurry in the aspect of removal rate,and shows the advantage of shear thickening mechanism in the polishing process.According to shear thickening property of non-Newtonian slurry,an experimental platform is set up which is suitable for non-Newtonian polishing slurry.In the polishing process,roughness,removal rate and surface quality are the evaluation indexes of polishing results by changing the experiment conditions.According to the results of single factor experiment and orthogonal experiment,the optimal experiment conditions and prescription of slurry are got with variance analysis.The results show that using the non-Newtonian polishing slurry,the removal rate can reach 10mg/h,and the roughness can reach 5nm;after polishing the workpiece has an extremely surface and there is no any scratches on the polished surface.