• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.81-81
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• 2003

최근 유한요소법을 이용하여 절삭가공을 해석하는 연구가 많이 발표되고 있다. 이 때 가장 문제되는 점이 피삭재에서 칩으로 분리하는 조건이다. 일반적으로 칩 분리 조건이라 일컬어지는 이 조건을 어떻게 설정할 것인가에 대해 현재까지도 많은 연구가 이루어지고 있다. 현재까지 제시된 칩 분리 판별 조건은 두 가지 유형 - 기하학적, 물리적으로 나눌 수 있다. 기하학적 칩 분리 조건은 공구 끝단과 바로 앞 요소의 거리를 기준으로 정해진 특정한 값에 도달하면 요소가 분리되는 혹은 없어지는 방법을 이용하는 것이며(Fig. 1 참조), 물리적 칩 분리 조건은 요소 내의 소성변형률 혹은 변형률 에너지 밀도함수 등의 값을 기준으로 분리시키는 방법이다. 본 연구에서는 상용 유한요소 해석 프로그램인 ANSYS를 이용하였으며 이 프로그램에서 제공하는 element birth/kill 기법을 이용하여 기하학적 판별조건에 도달하면 공구 끝단 앞의 요소가 사라지는 방법을 취하였다. Fig. 2는 절삭가공을 위한 유한요소 모델링을 나타낸다. 칩-공구 접촉 부위에 접촉요소를 사용하였으며, 피삭재의 왼쪽과 아래쪽 부위는 각각 변위구속을 하였다. 공구의 이동은 변위경계조건의 값을 변화시킴으로써 구현하였다. 절삭력을 비교함으로써 해석결과의 타당성을 검토하였으며, 피삭재 내의 응력, 변형률 분포 등을 살펴보았다.

• 한국정밀공학회지
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• 제19권2호
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• pp.228-236
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• 2002

In this study, the carbon steels, SM20C were machined with the tungsten carbide tipped circular saw to clarify the cutting-off characteristics in terms of tool wear. The results show that an improved performance in view of both the tool wear and the cutting efficiency was obtained by using oil base cutting fluid at the cutting speed of 100m/min with the feed of 0.06mm/tooth. The rake angle of 10$^{\circ}$ , clearance angle of 8$^{\circ}$ , nose radius of R0.1mm, and end cutting edge champer of 0.1mm$\times$25$^{\circ}$ are believed as the best tool geometries. The tool wear decreases due to using the saw of the disk of STS5 and the tool material of P30.

• 한국정밀공학회지
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• 제21권1호
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• pp.133-139
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• 2004

High speed machining (HSM) can reduce machining time with the high metal removal rate by high speed spindle and feedrate. This paper supports HSM technology using the small size tool with the optimal tool path generation and modification of tool change. The optimum tool path is generated to reduce cutting length of cavity pattern and change the cutting tool for preventing the tool breakage by wear. The tool path is modified with the experiment data of tool wear and breakage to support tool change on reasonable time. The result can contribute to HSM technology of high hardness materials using the small size end-mill.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.569-574
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• 2002

As consumer's desire becomes various, agility of mold manufacturing is most important factor for competence of manufacturer. In common works to use commercial CAM system to generate tool path, some decision making process is required to produce optimal result of CAM systems, The paper proposes a methodology for computer-assisted tool selection procedures for various cutting type, such as rough, semi-rough and finish cuts. The system provides assist-tool-items for machining of design model part of injection meld die by analyzing sliced CAD model of die cavity and core. Also, the generating NC-code of the tool size is used to calculate machining time. The system is developed with commercial CAM using API. This module will be used for optimization of tool selection and planning process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.126-130
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• 1993

소경드릴가공은 많은 기계가가공중에서도 가장 곤란한 가공의 하나이다.그것은 가공구멍단면 이하의 공간속에서 공구강성이나 칩처리들이 고려되어야 한다는 엄격한 제한이 소경이란 형태에서 한층 어려워지기 때문이다.소경의 구멍가공은 최근 전자제품,우주항공기 부품,소형정밀부품, 섬유산업의 광섬유관련품 등에 까지 수요가 증가함에 따라 레이져가공,전자빔가공,전해가공과 같은 전기물리적가공법이 많이 사용되고 있지만 생산성 및 가공정밀도의 관점에서 만족스러운 결과를 얻을 수 없는 실정이다, 이에반해 기계가공인 소경드릴가공은 공구강성저하로 인해 쉽게 파손된다는 점은 있지만 가공정도가 양호하고 종횡비가 높은 가공이 가능하여 실용화가 가장 좋은 분야라고 할수 있다. 이로 인해 최근에는 여기에 관한 많은 연구가 지행되고 있다. 또한 기계가공의 자동화가 진전됨에 따라서 단일공국의 대표적 공구인 바이트의 결함을 검출하는것 못지않게 드릴의 마멸이나 절손의 검출 또는 예측이 중요한 문제로 부각됨에 따라 절삭저항의 이용이 증가할 것으로 생각된다. 따라서 본 연구에서는 ADI에 포함된 Si량이 드릴가공시 ADI의 피삭성에 미치는 영향을 절삭조건을 변화시켜 고찰함과 동시에 공구수명에 대하여 고찰하였다.

• 한국공작기계학회논문집
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• 제13권4호
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• pp.23-29
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• 2004

In this study, four kinds of $Si_3N_4$-based ceramic cutting tools with different sintering time were fabricated to investigate the relation among mechanical properties, grain size and tool life. They were used to turn gray cast iron at a cutting speed of 330m/min and depth of cut of 0.5mm and 1mm in dry, continuos cutting conditions. Multiple linear regression model was used to determine the relations among the mechanical property, grain size and the density. It was found that the combination of hardness and fracture toughness showed a good relation with tool life. It was also shown that hardness was the most important single element for the tool life.

• 한국생산제조학회지
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• 제19권5호
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• pp.710-715
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• 2010

This study developed an automatic tool change system of the SMA-based tool clamping device for applications of micro-machine tools. This paper first describes clamping and unclamping procedures of the automatic tool change system and its basic configuration. Second, it presents fabrication techniques of components, such as a heating/cooling system and a tool loader. Finally, it describes automatic tool change test conducted with a prototype in which the fabrication techniques of components were employed. As the results of the test, times needed for clamping and unclamping operations were estimated to 18(s) and 8(s) respectively. The experimental results confirm that the proposed automatic tool change system can be sucessfully applied to micro-machine tools.

• 한국생산제조학회지
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• 제7권4호
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• pp.123-129
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• 1998

Ceramic and CBN tools are available for the difficult-to -cut-materials such as hardened carbon tool steel. stainless steel and etc. Ceramic tools are suitable for continuous turning cut, not for intermittent milling cut. Ceramic tools are likely to be chipped and abruptly broken before the appearance of normal wear in turning. In this study, TiN coated ceramic tools were found to restrain the chipping, breaking and early fracture and to increase the critical cutting velocity owing to TiN coating in PVD method.

• 한국정밀공학회지
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• 제15권5호
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• pp.110-119
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• 1998

Dynamic cutting force variations in milling process were measured indirectly using spindle motor current. Magnitude of the spindle motor current is independent of cutting direction. Quasi-static sensitivity of the spindle motor current is higher than that of the feed motor current. Dynamic sensitivity of the spindle motor current is lower but cutting force was correctly represented by spindle RMS current in rough milling. In rough milling, chipping and tool fracture were well detected by the proposed tool fracture index using spindle motor current.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.581-584
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• 2003

The austenitic STS 304 stainless steel was turned to clarify the effects of tool geometry on the tool wear. The wear of TiN-TiCN-TiC-TiAlN coated tungsten carbide tool was the smallest, exhibiting larger wear in the order of Si-Al-O-N ceramic, TiN coated tungsten carbide, TiN-TiCN-TiN coated tungsten carbide, TiC-TiN cermet and M20 tungsten carbide tools at the same cutting conditions. The S-type tool of M20 with large approach angle showed the longest tool life of all tools used in this tests due to preventing the groove wear of the side cutting edge. The wear of the S-type tool with the rake angle of 15$^{\circ}$became smaller than with that of -5$^{\circ}$, but the tool with the nose radius of 0.8mm did not perform much better with increasing the rake angle.