• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.311-318
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• 2001

A three-dimensional numerical analysis of the flow and heat transfer characteristic of wood-flour-filled polypropylene melt in an extrusion die was carried out Used for this analysis were Finite Concept Method based on FVM, unstructured grid and non-Newtonian fluid viscosity model. Temperature and flow fields are closely coupled through temperature dependent viscosity and viscous dissipation. With large Peclet, Nahme, Brinkman numbers, viscous heating caused high temperature belt near die housing, Changing taper plate thickness and examining some predefined parameters at die exit investigated the effect of taper plate on velocity and temperature uniformities. In the presence of taper plate, uniformity at die exit could be improved and there existed an optimum thickness to maximize it.

• Elastomers and Composites
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• 제46권1호
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• pp.54-59
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• 2011

점탄성 흐름의 특성은 압출시 다이 스웰 현상에서 확인 할 수 있다. 본 연구는 이러한 점탄성 특성을 갖는 고무 컴파운드를 모세관 다이에서 비선형 점탄성 모델인 PTT 모델과 간략화된 점탄성 모델을 이용하여 압출현상을 모사하고 다이 스웰을 실험과 비교 하였다. 실험은 Fluidity Tester를 이용하였고 해석은 상용화된 CFD Code인 Polyflow를 이용하였다. 두 모델에 의해 예측된 다이 스웰은 실험과 유사한 결과를 보였다. 그러나 PTT 모델에서는 압력과 속도분포, 레저버의 모서리에서의 와류현상을 예측할 수 있었지만 간략화된 점탄성 모델에서는 예측할 수 없었다. 간략화된 점탄성 모델은 다이 내부의 세밀한 흐름현상을 예측하지는 못하지만 다이 스웰은 잘 예측할 수 있으며 PTT모델보다 해석시간이 매우 짧아서 이의 응용에 큰 장점을 갖고 있다고 판단된다.

• 고무기술
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• 제14권2호
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• pp.93-106
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• 2013

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.128-131
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• 2004

Magnesium alloys are being extensively used in weight-saving applications and as a potential replacement for plastics in electronic and computer applications. Magnesium alloy has some good characteristics, EMI shielding property and high specific strength. Nevertheless their high brittleness make it uneasy to process the magnesium. Magnesium alloys are extruded like aluminium alloys. The present work was done to find a characteristic of magnesium alloy(AZ31) changing the extrusion ratio 8.5, 19.1, 49 respectly and changing the die half angle $30^{\circ},\;45^{\circ},\;60^{\circ}$. Here this present done by the hydrostatic extrusion in the hot condition, $310^{\circ}$. The higher the extrusion ratio goes, the higher the extrusion force goes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.463-466
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• 2005

Restoring ductility or removing residual stresses is a necessary operation when a large amount of cold working is to be performed, such as in a cold-forging or warm forging process. The advantage of annealing temperatures was investigated. After Hydrostatic Extrusion process, extruded materials were annealed at $200^{\circ}C,\;350^{\circ}C,\;450^{\circ}C$ for 1 hour. Microstructure of the annealed material was observed to make an understand about the difference in mechanical properties.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.202-205
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• 2002

The micro-extruding die is a die for manufacturing of fine-wire by extruding process. The fine-wire made from the micro-extruding can be effectively applied to fields of semiconductor parts and medical parts etc. It is predicted that the demand of fine-wire in industry is more and more increasing. In this study $\Phi$ 50${\mu}{\textrm}{m}$ micro-drill which is coated with diamond is used for drilling of super micro-hole sues. For the machining of taper parts of entrance and exit, drill having $\Phi$ 9mm inclination angle 20$^{\circ}$ is used. This is useful for anti tool-breakage in drilling process. After micro-drilling, the polishing process by abrasive is carried out for increasing surface roughness.

• 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.

• 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.

• 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.

• 청정기술
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• 제4권2호
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• pp.32-40
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• 1998

Polypropylene(PP)과 polyethylene(PE) 분체를 혼합하여 공기정화용 여과재로 사용하기 위한 기공성 고분자 소재를 압출 소결법으로 제조하였다. PP와 PE로 구성된 기공성 고분자 소재는 녹는점이 낮은 PE가 용융되어 PP를 결합시킨 구조임을 주사전자현미경(scanning electron microscope) 분석으로 관찰할 수 있었으며, 고분자 소재의 압출 소결시 압출기 다이 헤드의 온도, 압출 속도, PE의 용융지수 및 첨가량 변화 등에 따른 기공성 고분자 소재의 기계적물성과 여과특성 변화를 시험하였다. 일정한 압출기 헤드 다이 온도와 압출 속도하에서 압출 소결법으로 제조된 기공성 고분자 소재의 여과효율이 PE의 첨가량과는 비례 관계를 나타내었으나 PE의 용융지수에는 반비례 관계를 나타냄을 관찰할 수 있었다. 압출 소결법으로 제조된 기공성 고분자 소재의 여과특성을 시험한 결과, PP와 PE로 구성된 기공성 고분자 소재가 공기정화용 여과재로 적용될 수 있음을 확인할 수 있었다.