Basic Research On The Method Of Shear Rheological Polishing For Concave Surface

In recent years,concave surfaces gradually cover many industrial products and components in medical,maritime,industrial parts,molds,biomedicine and other fields.Due to the structure limitation of polishing tools,it is difficult to polish concave surfaces.Based on the method of shear rheological polishing,various polishing schemes such as horizontal type and runner type is analyzed,an experimental platform for shear rheological polishing is established,the rheological characteristics and polishing principles of STP slurry is analyzed,computational fluid dynamics and specific experiments is combined to reveal establishment and distribution of the force rheological polishing removal function of concave surface.The polishing experiments of 6061 aluminum alloy concave surface and resin lens were carried out,specific research content is as follows:An experimental platform for concave curved surface force rheological polishing is set up.The experimental platform includes a force measuring device,a four-axis linkage device,a workpiece fixture,a circulating cooling system for force rheological polishing fluid,and a viscosity control system.A multi-axis linkage mechanism is developed to drive the spindle at a maximum speed of 3000 rpm and the polishing tank at a maximum speed of 400 rpm.According to the characteristics of STP slurry and polishing trajectory,the workpiece fixture is designed.The rheological properties of STP slurry were studied,and the effects of different dispersed phase concentrations and particle sizes on the rheological properties of polishing base slurry were investigated.Then,different types of abrasive,different abrasive particle size,different abrasive concentration,and different p H of STP slurry on rheological properties of polishing slurry were further explored.The results show that the rheological properties of polishing slurry can be roughly divided into three areas: shear thinning,shear thickening and shear thinning.Through the experiments of different parameter variables,the most suitable proportion for shear thickening polishing is selected: PHHP particle size is 13μm,mass fraction is 52.5%,abrasive component ratio is W1.6:W0.2=7:3,abrasive concentration is 4.5wt%,p H5 of polishing slurry.The finite element simulation of shear rheological polishing is studied.In order to get the setting of viscosity curve in the simulation model of the polishing slurry,the previous simulation of the polishing slurry was analyzed,and then the parameters of the polishing slurry were set with the setting parameters of the obtained polishing slurry.The simulation results show that the workpiece fixture has a great influence on the distribution of pressure field and velocity field.Taking the distribution of pressure field and velocity field as the evaluation index,the simulation results show a better polynomial distribution,and the peak pressure is verified by experiments and the correction coefficient of simulation pressure is obtained.The removal function of force rheological polishing is established.First,the basic equation of the removal function is established based on the classic Preston equation and the characteristics of force rheological polishing.Then the results of the pressure and velocity fields obtained by simulation are used to fit the specific mathematical formula of the removal function.Finally,combined with the experimental results,the simulation correction coefficient and the removal function which shows a good Polynomial distribution are obtained.The experimental study of the removal function and stability of the force rheological polishing was performed.The polishing experiments were performed under different polishing parameters.The experimental results obtained were compared with the theoretical values of the established removal function.Take five points on the contour and use the least square method to get the error within 4.7%.In order to investigate the high quality of the concave curved surface with force rheological polishing,polishing experiment was performed on the resin lens.Before polishing,there are a lot of obvious defects such as pits and scratches on the surface of the workpiece,after polishing,the workpiece basically reaches the mirror effect without obvious defects.