阎秋生,梁智镔,潘继生.集群磁流变抛光加工表面磁轨迹强度建模优化及加工均匀性研究[J].表面技术,2022,51(12):243-254.
YAN Qiu-sheng,LIANG Zhi-bin,PAN Ji-sheng.#$NP Modeling Optimization and Uniformity of Cluster Magnetorheological Polishing via Magnetic Trajectory Intensity in Machining Surface[J].Surface Technology,2022,51(12):243-254 |
| 集群磁流变抛光加工表面磁轨迹强度建模优化及加工均匀性研究 |
| #$NP Modeling Optimization and Uniformity of Cluster Magnetorheological Polishing via Magnetic Trajectory Intensity in Machining Surface |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.12.025 |
| 中文关键词: 磁流变抛光 数值分析 磁轨迹 表面粗糙度 均匀性 |
| 英文关键词:magnetorheological polishing numerical analysis magnetic trajectory roughness evenness |
| 基金项目:国家自然科学基金(U1801259，52075102) |
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| 中文摘要: |
| 目的 探究集群磁流变抛光过程中工艺参数和空间磁场分布特征对加工表面粗糙度不均匀性的影响，通过优化工艺参数，改善加工表面粗糙度的不均匀性。方法 提出一种包含有效加工轨迹和磁轨迹特征的磁轨迹强度数值模型，在数值模型基础上分析转速比、偏心距和往复摆动速度等运动参数对工件不同位置上有效加工轨迹和磁轨迹2种特征的影响，优化不同运动条件下的转速比。在集群磁流变抛光装置上进行硅片的抛光加工实验，利用白光干涉仪检测加工表面粗糙度和表面形貌，总结加工表面粗糙度的分布规律。结果 数值计算结果表明，无理数的转速比能避免出现不同周向位置的周期性波动特征，选用合适的转速比能够减小不同径向位置轨迹长度的差异，提高轨迹特征的均匀性。在无理数转速比条件下，通过改变工件偏心距和增加往复摆动会增大有效加工轨迹的覆盖范围，同时会缩短有效轨迹长度，使得加工效率降低。改变偏心距的运动模式可以改变运动轨迹上磁频数的分布规律，在偏心距为115 mm条件下，工件不同径向位置之间的平均磁场差值可以减小至0.019 T。实验结果表明，通过优化工艺参数后，加工表面粗糙度的变异系数相较于对照组平均下降了约37%。对照组在抛光后的不均匀情况与数值计算结果中的磁轨迹强度径向分布规律相吻合，在小转速比下表现为中心光滑、边缘粗糙的分布规律，在大转速比下表现为边缘光滑、中心粗糙的分布规律。在偏心距为115 mm、转速比为223∶60的优化工艺条件下，抛光硅片的粗糙度变异系数最小达到0.309，平均粗糙度为Sa 4.19 nm。结论 对比实验结果与数值模拟结果可知，磁轨迹强度数值模型能有效优化集群磁流变抛光工艺参数，有利于加工轨迹与磁轨迹特征的匹配，改善了工件抛光后的加工不均匀性。 |
| 英文摘要: |
| Cluster magnetorheological polishing is an efficient planar processing method, which can obtain nano-scale ultra-smooth surface roughness in the polishing process of photovoltaic wafers. The movement mode of the workpiece and the distribution characteristics of the spatial magnetic field have an important effect on the surface uniformity after polishing. The work aims to explore the effects of motion process parameters and spatial magnetic field distribution characteristics on the unevenness of roughness after processing in cluster magnetorheological polishing, and optimize the process parameters to improve the uniformity of surface roughness after processing. A numerical model of the magnetic trajectory intensity including the effective processing trajectory and magnetic trajectory features was proposed. On the basis of the numerical model, the effects of the three motion parameters, namely the rotational speed ratio, the eccentric distance and the reciprocating oscillation, on the two characteristics of the effective processing trajectory and the magnetic trajectory at different positions of the workpiece were analyzed and the speed ratio values in different motion modes were optimized by the model. The polishing experiments of silicon wafers were carried out on a cluster magnetorheological polishing device, and the surface roughness and surface morphology of multiple positions after processing were detected by a white light interferometer, and the roughness distribution was observed. Numerical analysis results showed that the irrational speed ratio could avoid the periodic fluctuation characteristics of different circumferential positions, and choosing the appropriate speed ratio could reduce the difference in the length of the trajectory at different radial positions and improve the uniformity of the trajectory characteristics. Under the condition of irrational speed ratio, changing the eccentricity of the workpiece and increasing the reciprocating swing increased the coverage of the effective processing trajectory, but increased the duty cycle, which resulted in a decrease in the length of the trajectory and a decrease in processing efficiency. Changing the motion pattern of the eccentricity could change the distribution of the magnetic field frequency on the trajectory. Under the condition of the eccentricity 115 mm, the average magnetic field difference between different radial positions of the workpiece was reduced to 0.019 T. The experimental results showed that the variation coefficient of the processed surface roughness under the optimized process parameters was reduced by an average of 37% compared with the control group. The unevenness after polishing in the control group was consistent with the radial distribution law of the magnetic trajectory intensity in the numerical calculation results. At a small speed ratio, the center was smooth and the edge was rough, and at a large speed ratio, the edge was smooth and the center was rough. Under the optimized process conditions of eccentricity of 115 mm and rotational speed ratio of 223∶60, the roughness variation coefficient of the polished silicon wafer was at least 0.309, and the average roughness was Sa 4.19 nm. By comparing the experimental results with the numerical simulation results, the numerical model of the magnetictrajectory intensity can effectively optimize the process parameters of the cluster magnetorheological polishing, which is conducive to the matching of the processing trajectory and the magnetic trajectory characteristics, and improves the unevenness of the workpiece after polishing. The method can further provide guidance for the optimal design of the magnetic field generating device and the structure dimension of the motion part of the cluster magnetorheological polishing device. |
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