Test on Magnetic Abrasive Finishing of Free-form Surface Based on Multi-axis Tool Path Trajectory

The work aims to obtain a better surface morphology and reduce the surface roughness of the workpiece through the magnetic abrasive finishing test of the free-form surface. UG was used to generate 3D surface model, and the processing module was entered after setting of the tool type, machining allowance and other pre-processing. The post-processing function was adopted to confirm the tool path, and obtain the standard tool position file including the tool position and attitude. The original path point of the tool was obtained after removal of the machining G code. The curvature value was obtained through the approximate solution of the three-point method, the mean value of curvature was set as the threshold for distinguishing feature points from non-feature points and the feature points from the original trajectory were drawn with the critical value of curvature. Cubic B-spline interpolation was performed on the feature points by the accumulated chord length parameterization. The corresponding coordinate values were extracted from the digital module and compared with the original point and the interpolation point, thus analyzing the error of the curve fitted in the z axis. Then, the posture of the end of the manipulator was calculated according to the tool axis vector. The different slot methods of magnetic pole were simulated and analyzed in Ansoft Maxwell software, and the better spherical slot magnetic pole form in theory was selected to increase the lapping force. The surface topography and surface roughness of aluminum alloy before and after grinding were compared through tests. By accumulating chord length parameter method for cubic B-spline interpolation, the trajectory points with uniform step length were obtained, and the initial tool path was optimized. To a certain extent, the disadvantage of the large difference in the stroke of the end effector at the same time was improved. Slotted was carried out on the spherical magnetic pole to change the uniform magnetic field into a non-uniform magnetic field, and at the same time, magnetic induction intensity of 20 mm diameter area at a distance of 2 mm from the magnetic pole increased from 0.556 T to 0.727 T, and on the grinding track with the same distance and length of 30mm, the change of the magnetic induction intensity gradient was increased, which increased the grinding force during the process of magnetic abrasive finishing. The above methods were used to grind the aluminum alloy and the surface roughness decreased from original average surface roughness of 8.38 μm to 3.37 μm after 20 minutes of grinding. Then, after continuous grinding for 40 minutes, the average surface roughness decreased from 3.37 μm to 0.56 μm. By observing the surface topography with super depth of field, it can be found that the spherical melt produced by WEDM on the original workpiece is removed, indicating that combined magnetic abrasive finishing of six degree of freedom manipulator and the optimized five-axis machining tool path can effectively improve the surface quality of the workpiece and reduce the surface roughness. Therefore, a new method is tried for the finishing of free-form surfaces. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.