吴金忠,邢百军,邹艳华,郑菲.低频交变磁场超精密平面磁力研磨加工研究[J].表面技术,2018,47(11):281-289.
WU Jin-zhong,XING Bai-jun,ZOU Yan-hua,ZHENG Fei.Ultra-precision Surface Magnetic Grinding by Low Frequency Alternating Magnetic Field[J].Surface Technology,2018,47(11):281-289 |
| 低频交变磁场超精密平面磁力研磨加工研究 |
| Ultra-precision Surface Magnetic Grinding by Low Frequency Alternating Magnetic Field |
| 投稿时间：2018-04-27 修订日期：2018-11-20 |
| DOI：10.16490/j.cnki.issn.1001-3660.2018.11.040 |
| 中文关键词: 磁力研磨 低频交变磁场 纳米级加工 研磨压力 SUS304不锈钢 |
| 英文关键词:magnetic abrasive finishing low frequency alternating magnetic field nano processing grinding pressure SUS304 stainless steel plate |
| 基金项目:辽宁省教育厅基金（2016TsPY04）；辽宁科技大学校青年基金（2016QN14） |
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| 中文摘要: |
| 目的 通过利用低频交变磁场下产生的变动磁力，改善传统磁力研磨加工中磁力刷变形、磨料结块、磨料利用率低等问题，实现平面超光滑、纳米级加工。方法 在电磁线圈中通入频率为3 Hz的交流电流，产生低频交变磁场。利用磁通密度测量仪（EMIC Gauss Meter GM 4002）对加工区域磁感应强度进行测定，考察低频交变磁场的磁场强度分布状况。设计组装一套研磨压力测量系统，利用数据记录处理软件对比分析低频交变磁场和直流磁场所产生的研磨压力，深入研究研磨工具（磁簇）在低频交变磁场作用下的变化规律。研制一套低频交变磁场平面磁力研磨加工装置，以SUS304不锈钢板为加工对象，并与直流磁场进行对比实验，验证利用低频交变磁场进行磁力研磨的可行性及加工性能。结果 低频交变磁场中各点磁感应强度均在峰值与谷值之间不断变化，其变化规律近似于正弦分布。在磁极边缘（R=7.5 mm），产生最大峰谷值；从磁极半径（R=6 mm）到磁极中心（R=2 mm），磁场强度逐步减弱。低频交变磁场下研磨压力值呈周期性变化，且研磨压力的平均值大于直流磁场下的值。磁簇在低频交变磁场作用下产生周期性振动。磁簇呈收缩状态时，磁性粒子带动磨料上浮于磁簇前端。当磁场方向改变时，磁簇先呈发散状态，然后收缩，此过程中磨料颗粒与磁性粒子再次混合。如此循环更新，不仅解决磁簇与工件接触后产生的变形问题，而且提高了磨料的利用率，保证研磨工具稳定。分别使用低频交变磁场和直流磁场对SUS304不锈钢板进行研磨，使用油基研磨液，主轴转数为350 rad/min，交流电流有效值为1.9 A，频率为3 Hz。第一阶段选择平均粒径为30 μm的电解铁粉和WA#10000的磨料颗粒，经过60 min研磨，表面粗糙度值分别为35.28 nm和81.36 nm；第二阶段选择平均粒径6 μm的羰基铁粉和1 μm的金刚石粉，研磨时间60 min，最终表面粗糙度值分别达到4.51 nm和17.58 nm。结论 利用低频交变磁场能够实现研磨工具（磁簇）的循环更新，提高磨料利用率。与直流磁场相比，利用低频交流磁场磁力研磨法所获得的加工表面均匀、无划痕，实现了平面超光滑纳米级加工。 |
| 英文摘要: |
| The work aims to solve the problems of magnetic brush distortion, caking of abrasive particles and lower utilization of abrasive particles by the variable magnetic force from the low frequency alternating magnetic field, so as to obtain ultra-smooth and nanoscale polishing surface. Alternating current with frequency of 3Hz was connected in the electromagnetic coil to generate the low frequency alternating magnetic field. The magnetic flux density of the processing area was measured by the EMIC Gauss Meter GM 4002 to investigate the magnetic field intensity distribution of the low frequency alternating magnetic field. A set of grinding pressure measurement system was designed and assembled and the KYOWA PCD-300A data recording and processing software was used to compare and analyze the magnetic force produced by the low frequency alternating magnetic field and the direct magnetic field. The change law of the grinding tool (magnetic particle cluster) under the action of low frequency alternating magnetic field was deeply studied. A set of plane magnetic grinding machine at low frequency alternating magnetic field was developed. The SUS304 stainless steel plate was used as the processing workpiece, and compared with direct magnetic field to verify the feasibility and processing performance of low frequency alternating magnetic field during the magnetic grinding. The magnetic flux density of each point in the low frequency alternating magnetic field changed continuously between peak value and valley value and, the law of change approximated to the sinusoidal distribution. The maximum value was generated at the pole edge (R=7.5 mm) and the magnetic intensity gradually decreased from the magnetic pole radius (R=6 mm) to the magnetic pole center (R=2 mm). The change law of grinding pressure was periodic change under low frequency alternating magnetic field, and the average value of grinding pressure was larger than that of direct magnetic field. Periodic vibration of magnetic cluster was produced under low frequency alternating magnetic field. When the magnetic cluster was at contraction state, the magnetic particles drove the abrasive particles to the front of the magnetic cluster. When the direction of the magnetic field changed, the magnetic cluster was divergent first, and then contracted. the abrasive particles and magnetic particles were mixed again. This cycle and update not only solved the deformation problem caused by the contact between the magnetic cluster and the workpiece, but also improved the utilization rate of the abrasive particles and ensured the stability of the grinding tool. Low frequency alternating magnetic field and direct magnetic field were used to grind SUS304 stainless steel plate respectively with oily grinding fluid, spindle speed at 350 rad/min, alternating current at 1.9 A (average value) and frequency at 3 Hz. In the first stage, the electrolytic iron powder with an average diameter of 30 μm and the abrasive particles of WA#10000 were selected, and the surface roughness values were improved to 35.28 nm and 81.36 nm after 60 min grinding. In the second stage, the carbonyl iron powder with average particle diameter of 6 μm and diamond powder of 1 μm were selected, the surface roughness reached 4.51 nm and 17.58 nm respectively after 60 min grinding. MAF process by low frequency alternating magnetic field can cycle and update the grinding tool (magnetic cluster) and improve the utilization ratio of the abrasive particles. Compared with the direct magnetic field, the surface obtained by MAF at low frequency alternating magnetic field is uniform and free from scratch, thus realizing the processing of ultra-smooth and nanoscale plane. |
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