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신봉철(B. C. Shin),하석재(S. J. Ha),강민형(M. H. Kang),허영무(Y. M. Heo),윤길상(G. S. Yoon),조명우(M. W. Cho) 한국소성·가공학회 2009 소성가공 : 한국소성가공학회지 Vol.18 No.2
Recently, the monitoring technology of machining process is very important to improve productivity and quality in manufacturing filed. Such monitoring technology has been performed to measurement using vibration signal, acoustic emission signal and tool dynamometer. However, micro machining is limited small-scale parts machining because micro tool is very small and weakness to generate signal in micro machining process. Therefore, this study has efficient sensing technology for real monitoring system in micro machine that is proposed to supplement a disadvantage of single-sensor by multi sensor. From experimental result, it was evaluated tool wear and cutting situation according to repetitive slot cutting condition and changing cutting condition, and it was performed monitoring spindle rpm and condition according to compare acceleration signal with current signal.
홍영준,김순호,강민철,김인 배 ( Y . J . Hong,S . H . Kim,M . C . Kang,I . B . Kim ) 한국열처리공학회 1993 熱處理工學會誌 Vol.6 No.3
Effects of aging treatment on the microstructural evolution of a rapidly solidified Al-Li-Cu alloy were investigated by diffcerential scanning calorimetry (DSC) and transmission electron microscopy(TEM). It was found that the precipitation sequence was : supersaturated solid solution α`→metastable δ`+stable precipitate T₁→stable precipitates δ+T₁. Two exothermic and two endothermic peaks are detected by DSC analysis. The two exothermic and endothermic peaks corresponded to δ` and δ+T₁ precipitation and dissolution reactions respectively. The enthalpy of δ` precipitation decreased with increasing of aging temperature and time until the finishing point of precipitation. The activation energy for precipitation of δ` was measured as 80KJ/㏖ and the energy for dissolution was 93KJ/㏖. These values are higher than those of Al-Li binary alloy. Peak hardness value (Hv 170) was obtained at 210℃ for 1hr aging treatment which coincided with finishing point of δ` precipitation.