空间弯管内表面磁粒研磨位姿轨迹优化试验研究OA北大核心CSTPCD

In the magnetic particle grinding test on the inner surface of the elbow, the yoke usually works in a single vertical grinding attitude. The magnetic abrasive particles driven by the yoke will continue to move in a single and parallel grinding trajectory on the inner surface of the elbow, which will lead to insufficient grinding coverage in the grinding area, and the grinding traces are likely to overlap and deepen, which is not conducive to the uniformity of grinding. Considering the flexible controllability of the manipulator to the attitude of the end grinding device, this paper proposes a processing method of yoke cyclic transformation grinding attitude. In the grinding process, the grinding trajectory of the magnetic abrasive particles was changed by adding a deflection angle to the initial grinding attitude of the head and end of the yoke grinding area, so that the superimposed grinding trajectory of the magnetic abrasive particles after the alternating movement of the forward feed and the reverse feed could show a cross-network structure, so as to increase the grinding coverage area of the grinding area, thereby improving the uniformity of grinding. On the premise of avoiding motion interference and insufficient magnetic stability, the deflection angle range of the yoke was selected through actual test. ADAMS simulation was used to simulate the trajectory of magnetic abrasive particles on the inner surface of the elbow driven by a single grinding attitude ( 0° deflection angle ) and a changing grinding attitude (5°, 10°, 15° deflection angle ). EDEM software was used to simulate and verify the grinding effect of the above grinding trajectory by placing dynamic magnetic field and magnetic abrasive particle group, and the grinding pressure of magnetic abrasive particles in the grinding process was simulated and analyzed. In order to improve the grinding efficiency, the magnetic field of spherical auxiliary magnetic poles of different sizes in the tube was simulated, and the selection of test size was completed. In the simulation results, it could be observed that with the increase of the initial grinding attitude angle of the magnetic yoke, the coverage rate, structural compactness and interleaving frequency of the magnetic abrasive particle trajectory were improved, which was beneficial to improve the grinding uniformity of the inner surface of the elbow. At the same time, the magnetic field gradient was increased in the grinding process, which had a positive impact on the cutting edge replacement and service life. After grinding, the cumulative energy on the inner surface of the elbow also increased, which meant that the grinding efficiency was improved. The simulation results were verified by the real test platform. The workpiece was a copper elbow with a diameter of 25 mm and a wall thickness of 1 mm. The processing parameters were set as follows: the yoke feed speed was 1 mm/min, the deflection angle was 0°, 5°, 10°, 15°, the rotation speed was 750 rad/min, the grinding gap was 4 mm, the auxiliary magnetic pole was ϕ5 mm, and the abrasive particle size was 150 μm. From the surface morphology after 50 min of processing, it could be seen that the grinding marks in the processing area of a single grinding attitude (0° deflection angle) were different in depth and had strong distribution differences. The measured surface roughness was reduced from 1.063 μm before grinding to 0.3 μm. In the processing area of 5°, 10° and 15° alternate grinding attitude of the magnetic yoke, with the increase of the grinding attitude angle of the magnetic yoke, the grinding trace gradually became shallower, the surface flatness and the integrity of the defect removal were higher. The measured surface roughness was 0.273 μm, 0.222 μm and 0.189 μm, respectively. The amount of material removal was 72 mg, 78 mg, 89 mg and 106 mg, respectively. Observing the law, it can be found that the two are consistent with the change trend of the simulation results. Therefore, increasing the initial grinding angle of the yoke reasonably can effectively improve the grinding efficiency and obtain better surface quality after grinding.