| Force induced rheology polishing is to remove the surface material of the workpiece by using the unique shear thickening characteristic of the polishing liquid.Deterministic polishing mainly refers to the quantitative removal of the surface material of the workpiece by controlling the removal function and residence time,which focuses on the control of the shape accuracy of the machined workpiece.The establishment of the removal function plays an important role in the removal and removal distribution,and is one of the keys to deterministic removal polishing.Therefore,this paper will study the removal function of force rheological deterministic polishing,establish an experimental platform for force rheological deterministic polishing,analyze the rheological properties of polishing fluid and the principle of deterministic polishing,combined with computational fluid dynamics and specific Experiments reveal the distribution law and establishment method of the force rheological deterministic polishing removal function.The specific research content is as follows:The experimental platform for force rheological deterministic polishing is constructed.The experimental platform includes a force measuring platform,a four-axis linkage device,a workpiece fixture,a force rheology polishing liquid circulation cooling system,and a viscosity control system,and develops a multi-axis linkage mechanism to drive the spindle.The maximum speed is 3000 rpm and the maximum speed of the polishing tank is 400 rpm.The deterministic polishing head is designed,and according to the characteristics of the polishing liquid,a wedge-shaped groove polishing head is selected for deterministic removal polishing.The rheological properties of the rheological polishing fluid were studied.The effects of different dispersed phase concentrations and particle sizes on the rheological properties of the polishing base were investigated.Studies have shown that the rheological properties of the polishing fluid are roughly divided into three regions,shear thinning,shear thickening,and shear thinning.After experiments with different parameter variables,the most suitable polishing ratio for the shear thickening zone was selected: PHHP particle size was 13 μm,mass fraction was 52.5%,abrasive grain size was 3000#,and abrasive grain concentration was 10 wt%.The finite element simulation of force rheological deterministic polishing was carried out.The computational fluid simulation software CFX was used to simulate the motion state of the polishing fluid during the polishing process,including the selection of theoretical model,the setting of grid encryption,and the setting of material properties.Then the polishing conditions under specific rotation speed and polishing clearance are simulated.The distribution of pressure field and velocity field is approximate Gaussian,and the peak velocity and peak pressure are theoretically calculated and experimentally verified.The correction coefficient of simulation pressure is obtained.The influence of different tooth numbers and groove depth on the pressure field and velocity field of the wedge-shaped polishing head was explored.A wedge-shaped polishing head(slot number 12,groove depth 3 mm)suitable for deterministic polishing research was selected.The force rheological determination removal function is studied.According to the classical Preston equation,combined with the characteristics of force rheological deterministic polishing,the basic equation of the removal function is established.Then,using the results of the pressure field and the velocity field obtained by the simulation,the exact mathematical formula of the removal function is fitted by origin;Finally,combined with the experimental results,the simulation correction coefficient and the polishing fluid concentration correction coefficient are obtained,and the removal function exhibits a good Gaussian distribution.Using the analysis of variance,the influence of the main parameters on the removal rate was the polishing head rotation speed(34.38%),the polishing gap(33.45%),and the polishing liquid concentration(32.17%).Experiments on the removal function and stability of force rheological deterministic polishing were carried.Polishing experiments under different polishing parameters were carried.The experimental results were compared with the theoretical values of the established removal functions,error within 7%.The cross-sectional profile is basically the same.Through the linear trajectory polishing experiment,Force rheology deterministic polishing has high stability. |
