Analysis of machining-induced residual stresses of milled aluminum workpieces, their repeatability, and their resulting distortion
Analysis of machining-induced residual stresses of milled aluminum workpieces, their repeatability, and their resulting distortion
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DOI：
10.1007/s00170-021-07171-7
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发表时间：
2021-05
期刊：
影响因子：
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通讯作者：
D. Weber;B. Kirsch;C. R. Chighizola;C. D'Elia;B. Linke;M. R. Hill;J. Aurich
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文献类型：
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作者：
D. Weber;B. Kirsch;C. R. Chighizola;C. D'Elia;B. Linke;M. R. Hill;J. Aurich
加工残余应力是薄壁铝整体件变形的主要驱动因素。在开发补偿技术以最小化畸变之前，必须充分了解加工对MIRS的影响。这意味着，不仅研究不同工艺参数对MIRS的影响是重要的。此外，必须考虑相同加工条件下产生的MIRS的可重复性。在过去的研究中，没有关注加工样品的MIRS的统计置信度。在本文中，研究了不同加工模式下，包括每齿进给量和切削速度的变化，MIRS的重复性。在一个样品和不同样品上进行多次钻孔测量，使用相同的参数集进行加工，是调查的一部分。此外，还研究了两种不同夹紧策略对MIRS的影响。结果表明，对于稳定加工（最大正常MIRS的重复性标准偏差在16 - 34%之间），给出了MIRS的总体重复性，而不稳定加工（通过力信号中的振动检测）的重复性较差（54%），与所使用的夹紧策略无关。在进一步的实验中，在铣削表面移除1毫米厚的晶圆，显示了MIRS与其畸变之间的联系。数值应力分析表明，在不同的加工模式下，实测应力数据与加工引起的变形是一致的。研究发现，更多和/或更深的MIRS会导致更多的失真。
Machining-induced residual stresses (MIRS) are a main driver for distortion of thin-walled monolithic aluminum workpieces. Before one can develop compensation techniques to minimize distortion, the effect of machining on the MIRS has to be fully understood. This means that not only an investigation of the effect of different process parameters on the MIRS is important. In addition, the repeatability of the MIRS resulting from the same machining condition has to be considered. In past research, statistical confidence of MIRS of machined samples was not focused on. In this paper, the repeatability of the MIRS for different machining modes, consisting of a variation in feed per tooth and cutting speed, is investigated. Multiple hole-drilling measurements within one sample and on different samples, machined with the same parameter set, were part of the investigations. Besides, the effect of two different clamping strategies on the MIRS was investigated. The results show that an overall repeatability for MIRS is given for stable machining (between 16 and 34% repeatability standard deviation of maximum normal MIRS), whereas instable machining, detected by vibrations in the force signal, has worse repeatability (54%) independent of the used clamping strategy. Further experiments, where a 1-mm-thick wafer was removed at the milled surface, show the connection between MIRS and their distortion. A numerical stress analysis reveals that the measured stress data is consistent with machining-induced distortion across and within different machining modes. It was found that more and/or deeper MIRS cause more distortion.