• Journal of Magnetics
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• 제13권3호
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• pp.102-105
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• 2008

This study examined the feasibility of the combining HDDR-process (hydrogenation, disproportionation, desorption and recombination) with mechanical milling to prepare single domain $Nd_2Fe_{14}B$ particles from a Nd-Fe-B alloy ingot. The $Nd_{15}Fe_{77}B_8$ alloy was HDDR-treated and then subjected to a roller-milling. In the HDDR-treated $Nd_{15}Fe_{77}B_8$ alloy, very small $Nd_2Fe_{14}B$ grains comparable to their critical single domain size(0.3 ${\mu}m$) were observed. These fine individual grains were separated successfully along the grain boundaries by a roller-milling. The separated $Nd_2Fe_{14}B$ grains were found to be single domain particles. These results suggest that single domain particles of the $Nd_2Fe_{14}B$ phase can be prepared from a Nd-Fe-B ingot alloy by combining a HDDR-process with mechanical milling.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제3회 금형가공 심포지엄
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• pp.255-259
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• 2004

3-D micro structures and micro tools are fabricated using MEDM (Micro Electric Discharge Machining). To make micro structures, micro electro discharge milling process is applied. During micro electro discharge milling, electrode (tool) wears both axial and radial direction. To compensate tool wear which influences significantly machining accuracy, overlap machining path is proposed. Machining characteristics of micro electro discharge milling is investigated in considering of depth of cut and capacitance of discharge circuit. Micro complex shaped tools are fabricated using REDM (reverse electro discharge machining). Sacrificial electrode is machined through electro discharge milling process and is used as electrode to make micro tools. Using this process several micro tools shape of 'ㄷ', 'ㅁ' and 'o' are fabricated. With these complex shaped tools, micro machining is successfully applied repeatedly.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1221-1222
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• 2013

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.931-932
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• 2013

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.86-89
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• 2002

In NC machining, the ability to automatically generate an optimal process plan is an essential step toward achieving automation, higher productivity, and better accuracy. For this ability, a system that is capable of simulating the actual machining process has to be designed. In this paper, a milling process simulation system for the general NC machining was presented. The system needs first to accurately compute the cutting configuration. ME Z-map(Moving Edge node Z-map) was developed to reduce the entry/exit angle calculation error in cutting force prediction. It was shorn to drastically improve the conventional Z-map model. Experimental results applied to the pocket machining show the accuracy of the milling process simulation system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1054-1058
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• 1995

There have been many research works for the indirect cutting force measurement in machining process, which deal with the case of one-axis cutting process. In multi-axis cutting process, the main difficulties to estimate the cutting forces occur when the feed direction is reversed. This paper presents the indirect cutting force measurement method in contour NC milling processes by using current signals of servo motors. An artificial neural network (ANN) system are suggested. An artificial neural network(ANN) system is also implemented with a training set of experimental cutting data to measure cutting force indirectly. The input variables of the ANN system are the motor currents and the feedrates of x and y-axis servo motors, and output variable is the cutting force of each axis. A series of experimental works on the circular interpolated contour milling process with the path of a complete circle has been performed. It is concluded that by comparing the ANN system with a dynamometer measuring cutting force directil, the ANN system has a good performance.

• 자원리싸이클링
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• 제20권6호
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• pp.37-42
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• 2011

구리관의 절단 공정에서 구리 칩 스크랩이 발생해왔다. 분쇄에 의하여 구리칩 스크랩을 분말화하는 가능성이 연구되었다. 본 연구에서는 로드 밀링, 수평식 볼밀링과 같은 두 가지 타입의 분쇄 방식이 적용되었다. 구리 칩은 로드 밀링에 의하여 분말 형태로 분쇄될 수 없었다. 반면에 36시간 이상 수평식 볼밀링에 의하여 구리칩은 분말로 변화하였다. 수평식 볼밀링에 의한 구리 칩의 분말로 재활용이 가능하였고 48시간 동안 밀링된 원료중 $75{\sim}150{\mu}m$ 범위의 분말은 25.3%이였다.

• 한국정밀공학회지
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• 제31권5호
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• pp.381-387
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• 2014

This paper introduces a system to machine micro-sized patterns effectively on surface based on micro-milling process using tools with simultaneous rotation and oscillation, oscillation micro milling. To review the effectiveness of proposed concept, we integrated a micro-spindle supported by active magnetic bearings with a precision 3-axis air bearing stage using double-wedge mechanism, and tested this oscillation milling. Two types of oscillation milling were tested, which are linear oscillation milling with a flat end mill and elliptical oscillation milling with a ball end mill with 0.3 mm of diameter. The spindle was rotating 110 krpm and workpiece was moving constant speed of 2~8 mm/sec during the oscillation milling. As the results, multiple oval shape dimples were generated in regular spacing, and the variation of elliptical motion made different shapes of patterns. The results showed that proposed oscillation milling can be successfully used for machining repeated micro-patterns.

• 한국자기학회지
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• 제9권4호
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• pp.217-222
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• 1999

공업적으로 세라믹공정에 많이 사용되고 있는 습식 볼밀링으로 NiCuZn ferrite 제조과정 중 혼입되는 불순물의 양을 조사 검토하였다. NiO, CuO, ZnO 및 Fe2O3의 화학조성을 변화시켜 25 vol%로 혼합하고 스테인레스 볼밀로 습식방법을 이용하여 18시간 분쇄한 후 건조시켜 $700^{\circ}C$ 3시간 하소하였다. 하소한 분말을 다시 상기와 같은 방법으로 65시간 스테인레스 볼밀로 최종 분쇄하여 저온소결용 NiCuZn ferrite(NCZF) 소재를 제조하였다. NCZF 연자성 소재를 만드는 동안 혼합 분쇄과정에서 혼입되는 불순물의 스테인레스 스틸의 양은 산화철 및 산화니켈의 함량에 많은 영향을 받았고, 하소 후의 분쇄과정에서 혼입되는 불순물의 양은 결정화된 정도에 따라 영향을 받았다. 전자기적 특성을 갖는 화학조성의 조절을 위하여, 출발원료의 함량에 따라 분쇄과정에서 혼입되는 스테인레스 스틸의 함량을 도출하는 형식을 유도하였다.

• 한국재료학회지
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• 제13권3호
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• pp.169-173
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• 2003

W-Cu composite powders can be prepared by mechanochemical process, where the $WO_3$-CuO composite powders were mechanically synthesized from the elemental oxide powders and subsequently reduced to W-Cu composite powders. In the present work, reduction behavior of$ WO_3$-CuO composite powders that were synthesized at different milling time was examined in terms of hygrometric analysis. In case of $WO_3$-CuO ball-milled for 20 h, the reaction temperature of CuO\longrightarrowCu became lower than in case of 1 h. Also, the reaction of $WO_3$\longrightarrow$WO_{2.9-2.72}$ and $WO_{2.9-2.72}$ \longrightarrow$WO_2$were shifted to lower temperatures and the peaks were changed to much sharper shape. While the reaction of $WO_2$\longrightarrowW in case of ball-milling for 20 h started at lower temperature, the peak temperature was the same as in 1 h ball-milling. The reduced W particle size was somewhat finer fer 20 h ball-milling. It was considered that the refinement of oxide particles caused by ball-milling process leads to such a change in the reduction behavior.