• 대한기계학회논문집A
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• 제25권10호
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• pp.1541-1550
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• 2001

This paper describes experimental investigations in the direct extrusion of copper clad aluminum rods through conical dies. Composite materials consist of two or more different material layers. Copper clad aluminum composite materials are being used fur economic and structural purposes and the development of an efficient production method of copper clad aluminum composite material rods by extrusion is very important, It is necessary to know the conditions in which successful uniform extrusion ,and sound cladding may be carried out without any defects in the direct extrusion. There are several variables that have an influence on determining a sound clad extrusion. In order to investigate the influence of these parameters on the hot direct extrudability of the copper clad aluminum composite material rods, the experimental study have been performed with various extrusion temperatures, extrusion ratios and semi-cone angles of die. Subsequently, the microscopic inspection of interface bonding is carried out for extruded products. By measuring hardness, along extrusion way of products, a variation of hardness has been discussed. Proportional flow state has been considered by measuring radius ratio of Cu sleeve and Al core before and after extrusion.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.54-59
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• 2006

An analytical solution for deflection-load characteristics of a conical disk spring used especially in the automotive manual transmission clutch applications is proposed in order to take into account the effects of friction and large deformation. The conical disk spring, or the diaphragm spring, has a hinge support, an application point of release load at the tip of the fingers and an application point of clamp load near but inside the outer perimeter of the conical disk spring. The friction coefficient is assumed to be a constant regardless of the speed of deflection and the magnitude of loads. Comparison with experimental shows a good agreement with the analytical prediction. Also, the sensitivity of the clamp load due to variations in the geometrical parameters of the conical disk spring is calculated and discussed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 제5회 압출 및 인발가공 심포지엄
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• pp.23-32
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• 2002

The torsional forward extrusion is the process that is executed by punch travel and die rotation. The advantages of having the die rotation on this process are that forming load can be reduced and optimal die angle can be increased. This provides a possibility to extrude cold-worded material where a large extrusion force and die angle are required. Also, this process can improve the material properties owing to the high deformation and uniform strain distribution. The forming load and optimal die angle of this process are determined by the upper bound analysis using stream function and the optimization technique. To verify the theoretical result, we have carried out experiments and FE simulations using DEFORM3D.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.329-332
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• 2002

The upper bound analysis by stream function is used to study the torsional forward extrusion. The torsional forward extrusion process not only reduces forming load but also increase optimal die angle. Optimal die angle is determined by the optimization technique. The advantages of this process are that the low capacity of pressing machine can be used and the process with a large die angle can be applied. To verify the theoretical result, we have carried out experiments using model material (plasticine) and FE simulations using DEFORM3D.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.31-34
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• 2004

A new extrusion process of the circular section product with helical fins could be developed by using rotating extrusion dies. The twisting of extruded product is caused by the twisted conical die surface connecting the die entrance section and the die exit section linearly. But, until now, because the process has used fixed extrusion dies, it needs high pressure in order to twist billet and form fin shape on the surface of billet. So, during extruding billet, in order not to twist billet, the extrusion dies is needed to rotate itself instead of twisting billet. And in order to rotate dies, the shape of inside contour of extrusion dies must have conical type with twisted Inclined die surface connecting the die entrance section and the die exit section linearly. The results of experiments show that, in spite of using twisted extrusion dies, twisting of the billet should not happen because of rotating dies in the opposite direction of twisting direction of billet during extruding billet, and, from the results, it shows that it can decrease the power of extrusion pressure and could prevent crack of teeth for fin forming.

• 대한기계학회논문집
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• 제11권3호
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• pp.509-518
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• 1987

본 연구에서는 냉간 축대칭 전방 압출에 가중잔류항법을 적용하여 재료의 가 공 경화 및 강소성 경계를 고려하는 프로그램을 개발하여 변형도, 응력, 변형력, 강소 성 경계등을 FEM과 동일한 조건에서 비교 해석하고 다른 공정에 적용할 수 있게 하고 또한 곡면다이와 원추형다이를 설계 제작하여 다이의 형상과 단면 감소율이 변형도와 응력 분포에 미치는 영향을 검토하고 압출된 제품의 성질을 분석하여 실제 공정에 이 바지하며 이론 계산과 실험을 비교함이 목적이다.

• 한국광학회지
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• 제10권6호
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• pp.500-506
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• 1999

레이저 다이오드와 수신광검출기가 집적된 소자를 V-홈을 가진 실리콘 광학벤치에 flip-chip 본딩하고, 경사면을 가진 하나의 단일모드 광섬유와 수동정렬하는 방법을 사용하여 가입자망을 위한 저가의 양방향 송수신 모듈을 설계, 제작하였다. 광섬유의 단면 경사각에 따른 송신광결합 효율과 수신광결합 효율사이의 병목점을 찾기 위해 Gaussian빔 모델을 사용하여 수평정렬거리, 광섬유 단면 경사각, 수직정렬오차등의 변수에 따른 광결합계수를 계산함으로써, 최적의 광정렬조건을 예측하였다. 또한 실리콘 광학벤치에서 광결합효율을 측정하여 광섬유의 수직정렬오차에 따른 광결합계수의 감소가 광섬유의 경사각에 의해 보상될 수 있다는 계산결과의 타당함을 확인하였다. 실제의 sub-module 제작 및 광결합 실험에서 송신빔이 광섬유 단면에 반사되어 PD로 입사되는 것을 최소화하기 위하여 광섬유 단면을 경사절두원추형으로 제작함으로써 PD의 수신 잡음을 $30mu$m 이상의 정렬거리에서 -35dB이하로 유지할 수 있었다. 같은 조건에서 단면 경사각이 $12^{\circ}$인 광섬유에 의해 -12.1dB의 송신출력과 0.2A/W의 responsivity를 얻을 수 있었다.