| CHEN Xiao-ming,XU Cheng-yu,JI Dong-feng,LIU Ning,ZHU Yong-wei.Research on Low Roughness Magnetic Grinding of TC4 Titanium Alloy Based on Mixed Particle Size[J],52(12):112-118, 159 |
| Research on Low Roughness Magnetic Grinding of TC4 Titanium Alloy Based on Mixed Particle Size |
| Received:September 28, 2023 Revised:November 07, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.12.010 |
| KeyWord:mixed particle size magnetic abrasive finishing surface roughness magnetic chain |
| Author | Institution |
| CHEN Xiao-ming |
College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing , China;Jiangsu Maritime Institute, Nanjing , China |
| XU Cheng-yu |
College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing , China |
| JI Dong-feng |
College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing , China |
| LIU Ning |
College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing , China |
| ZHU Yong-wei |
College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing , China |
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| Abstract: |
| To obtain a lower roughness surface of TC4 titanium alloy parts, magnetic abrasives with different particle sizes were prepared by the bonding method in this paper. Abrasives with particle sizes of 150-250 μm, 63-106 μm, and mixed abrasives of both sizes were successively used for magnetic abrasive finishing (MAF) comparison experiments, and the feasibility of low roughness MAF of TC4 titanium alloy based on mixed-size abrasives (MSA) was analyzed. Based on the dynamic model of magnetic abrasives, the microstructure of the magnetic chains in MSA was analyzed by the minimum energy principle, and the magnetic chains of single-size abrasives (SSA) and MSA were compared by the stereomicroscope. Results showed that the surface roughness Ra of the titanium alloy workpiece processed by SSA and MSA was both about 0.11 μm at 12 minutes, but it would continue to decrease in the MSA finishing. The lowest roughness Ra in MSA finishing was 0.084 μm at 16 minutes, which was 20% lower than that of SSA finishing. The initial scratches and pits on the workpiece surface were better removed and the surface texture was denser after MSA finishing. In the observation experiment, it was found that the magnetic chain formed by the single-size particles had more bifurcations and voids, which were relatively loose, while the bifurcations and voids of the magnetic chain formed by the mixed-size particles were significantly reduced, and the combination was closer with the decrease of the particle size ratio. Besides, the particle energy of the magnetic chain formed by large-size particles was the smallest, which was about ‒3.6×10‒13 J, and then followed by mixed particle size magnetic chain structure with particle energy of approximately ‒2.1×10‒13 J. According to the principle of minimum energy, the smaller the energy is, the more stable the structure is. The magnetic chain structure of small-size particles with particle energy of approximately ‒0.45×10‒13 was hard to form, because the particle energy in the small-size magnetic chain was 5-9 times higher than that in the large-size and mixed-size. Obviously, the single-chain and double-chain structures formed by large-size particles were the most stable, and then followed by the double-chain formed by mixed-size particles. In the SSA, due to the large grinding pressure and diamond particles, the scratches on the workpiece surface were prominent in the MAF with large-size particles. Furthermore, it was difficult to obtain a lower surface roughness in the MAF with small-size particles attributed to its low grinding pressure and weak cutting ability. In the MSA, the small-size particles did not form a separate magnetic chain but were adsorbed in the gap of the large-size magnetic chains, which contributed to the rigidity and density of the magnetic brush. The large particle size abrasives had a strong cutting ability, and the small particle size abrasives helped to eliminate the scratches generated by the large particle size abrasives. Due to the synergistic processing of the different abrasive sizes, the surface roughness of the TC4 titanium alloy was significantly improved. |
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