• Tribology and Lubricants
• /
• 제15권4호
• /
• pp.297-303
• /
• 1999

O-rings in automotive engines are important components such as a coolant pipe, engine oil circulating lines and fuel injector for sealing that makes efficient performance of the engine. Life cycle of O-rings is effected in environments of the O-ring seal, like that applied pressure, working temperature, precompressed ratio and materials. It is related in extrusion, expansion and fatigue failure of O-rings. In this paper, an pressurized, compressed elastomeric O-ring inserted into a rectangular groove is analysed numerically using the nonlinear finite element method. The calculated FEM results showed that extrusion ratio and contact stress are strongly related to the gap clearance and edge radius of the groove.

• 소성∙가공
• /
• 제15권2호
• /
• pp.143-147
• /
• 2006

Effect of processing condition on the hot extrusion of Al-Zn-Mg-Sc alloy was investigated. For this purpose, hot compression test and FE-simulation were conducted via Thermecmaster-Z and DEFORM-3D, respectively. The microstructure evolution during hot extrusion and post heat-treatment was investigated and deformation mechanisms were analyzed by constructing processing map. FE-simulation results show that the temperature difference between container and billet has considerable influence on the final shape of extruded T-shape bar. The relation between applied load and processing time was predicted by the FE-analysis as well as punch speed vs. stroke chart.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2005년도 추계학술대회 논문집
• /
• pp.202-205
• /
• 2005

Effect of processing condition on the hot extrusion of Al-Zn-Mg-Sc alloy was investigated. For this purpose, hot compression test and FE-simulation were conducted via Thermecmasteer-Z and DEFORM-3D, respectively. The microstructure evolution during hot extrusion and post heat-treatment was investigated and deformation mechanisms were analyzed by constructing processing map. FE-simulation results show that the temperature difference between container and billet has considerable influence on the final shape of extruded T-shape bar. The relation between applied load and processing time was predicted by the FE-analysis as well as punch speed vs. stroke chart.

• 한국정밀공학회지
• /
• 제12권11호
• /
• pp.91-97
• /
• 1995

In this study, a deformation model for the regular polygonal-shaped tubes from hollow-cylindrical billets is proposed and a kinematically admissible velocity field is obtained from this deformation model. The final stage upper-bound extrusion load and the average extruded length are determined by minimizing the total power consumption with respect to chosen parameters. Experiments have been carried out with hard solder billets at room temperature. The theoretical predictions of the extrusion load are in good agreements with the experimental results and there is generally reasonable agreement in average extruded height between theory and experiment.

• 소성∙가공
• /
• 제8권4호
• /
• pp.374-383
• /
• 1999

To determine the flow stress of semi-solid materials, a new combined method has been studied by experimental and analytic technique in the current approach. Using backward extrusion experiment and its numerical analysis, the characterization scheme of semi-solid materials according to the change of initial solid volume fraction has been proposed. Because that solid volume fraction is sensitive to temperature change, it is required to precisely control the temperature setting. Model materials can guarantee the establishment of material characterization technique from the noise due to temperature change. Thus, clay mixed with bonded abrasives was used for experiment and the change of initial solid fraction was copied out through the variation of mixing ratio. Upper bound method was adapted to increase in efficiency of the calculation in numerical analysis and new kinematically admissible velocity field was employed to improve the accuracy of numerical solution. It is thought that the material characterization scheme proposed in this study can be applied to not only semi-solid materials, but also other materials that is difficult to obtain the simple stress state.

• 한국주조공학회지
• /
• 제17권5호
• /
• pp.494-501
• /
• 1997

In order to manufacture large rod preforms of 2014 Al alloy with a good mechanical property by spray forming method, it was spray-formed at a droplet temperature of $715^{\circ}C$, a droplet flight distance of 400mm, and a spraying angle of $35^{\circ}$. The rod preforms were extruded at $397^{\circ}C$ with the die temperature of $420^{\circ}C$ under the hot extrusion ratio 21:1 and T6 heat treatment was performed. The 2014 Al alloys cast by hot top process were also extruded and heat-treated at the same condition as a reference material. Microstructural observation and tensile test were carried out to investigate the effects of extrusion on microstructure and mechanical property of spray-formed Al alloy. Spray-formed Al alloys had many porosities due to inappropriate process conditions such as long droplet flight distance and low droplet temperature but have fine equiaxed grain. These porosities were reduced with decreasing in grain size by hot extrusion. Ultimate tensile strength and yield strength of spray formed-extruded 2014 Al alloy were inferior to those of the normal cast-extruded 2014 Al alloy, but elongations were superior. The control of porosity was important to get spray formed preform with a good mechanical property.

• 소성∙가공
• /
• 제31권3호
• /
• pp.117-123
• /
• 2022

In this study, a commercial AZ61 magnesium alloy is extruded at 300 ℃ and 400 ℃ and the microstructures, mechanical properties, and high-cycle fatigue properties of the extruded materials are investigated. Both extruded materials have a fully recrystallized microstructure with no Mg₁₇Al₁₂ precipitates. The average grain size and maximum basal texture intensity of the extruded material increase with increasing extrusion temperature. The material extruded at 400 ℃ (AZ61-400) has higher tensile yield strength and lower compressive yield strength than the material extruded at 300 ℃ (AZ61-300) because of the stronger basal texture of the former. Because of coarser grain size, the tensile elongation of AZ61-400 is lower than that of AZ61-300. Despite the differences in microstructures and tensile/compressive properties, the two extruded materials have the same fatigue strength of 110 MPa. This is because the finer grain size of AZ61-300 causes an increase in fatigue strength, but its weaker texture causes a decrease in fatigue strength. In both extruded materials, fatigue cracks initiate at the surface of fatigue specimens at all stress amplitudes tested.

• 한국식품영양과학회지
• /
• 제44권8호
• /
• pp.1212-1218
• /
• 2015

본 연구는 저온 및 재래식 압출성형 공정에 따른 쌀 야채류 압출성형의 항산화 활성에 대해 분석하였다. 압출성형 조건은 수분 함량 25%, 스크루 회전속도 150 rpm으로 고정하였다. 저온 압출성형 조건은 사출구 온도 $80^{\circ}C$, $CO_2$ 주입량 300 mL/min, 재래식 압출성형은 사출구 온도 $140^{\circ}C$, $CO_2$ 0 mL/min으로 조절하였다. 원료는 쌀 분말에 단호박, 토마토, 딸기 및 녹차 분말을 각각 10%씩 혼합하여 사용하였다. 단호박 및 토마토 첨가한 압출성형물의 DPPH 라디칼 소거능은 저온 압출성형 공정보다 재래식 압출성형 공정에서 더 높았다. 단호박, 토마토 및 딸기를 첨가한 압출성형물은 압출성형 후 총 페놀 함량이 증가하였으며, 저온 압출성형물보다 재래식 압출성형물에서 총 페놀 함량이 다소 높았다. 총 플라보노이드 함량은 녹차를 첨가한 재래식 압출성형물이 18.82 mg/g으로 가장 높았다. 압출성형 후 단호박을 첨가한 압출성형물의 총 카로티노이드 함량은 낮아졌으나 토마토 압출성형물은 증가하였다. 토마토 압출성형물의 라이코펜 함량은 압출성형 후 증가하였으며, 재래식 압출성형에서 더 높았다. 딸기 압출성형물의 안토시아닌 함량은 저온 압출성형보다 재래식 압출성형 공정에서 높았다. 압출성형 후 녹차 압출성형물의 총 클로로필 함량은 감소하였으며 클로로필 a, b 및 총 클로로필은 저온 및 재래식 공정에 따른 유의적인 차이는 없었다.

• 한국식품영양과학회지
• /
• 제32권8호
• /
• pp.1270-1277
• /
• 2003

두유박과 옥분 혼합물의 압출성형물을 제조하기 위한 공정 조건의 위하여 스크류 속도 150∼250 rpm, 혼합물의 수분함량 20∼30%, 온도 100∼15$0^{\circ}C$의 조건에서 압출 성형하고, 반응표면분석법 (RSM)을 이용하여 최적 조건을 분석하였다. 공정 조건에 따른 팽화율에서는 스크류 속도가 높고 수분함량이 낮을수록 팽화가 크게 일어났고, 수분함량이 많을수록 용적 밀도를 높이는 것으로 나타났다. 절단강도의 경우 수분 함량에 따라 감소하다 증가하는 추세를 보여주었고, WSI는 스크류 속도와 수분함량에 WAI는 수분함량과 온도에 많은 영향을 받았다. 색도에서는 b＊ 값을 제외하고는 유의적인 차이를 보이지 않았다. 각 조건별 실험결과를 반응표면분석을 한 결과 팽화율과 용적 밀도, WSI, b＊ 값은 linear모델로 결정되었고, 절단강도와 WAI는 quadratic 모델이 유의성을 나타내었다. 압출 성형 공정의 최적화는 결정된 반응식과 반응표면 그래프를 이용한 결과 수치 최적화에서는 스크류 속도 250 rpm, 수분함량 22.43%, 온도 128.16$^{\circ}C$이었고, 모형적 최적화에서는 desirability가 0.727인 스크류 속도 250 rpm, 수분함량 22.43%, 온도 128.02$^{\circ}C$로 결정되었다.

• 한국식품과학회지
• /
• 제47권2호
• /
• pp.149-157
• /
• 2015

본 연구는 압출성형 된 옥수수 섬유질로부터 화학적 추출을 통해 SAX와 CFG 수율을 향상시키기 위해 반응표면분석법을 이용하여 최적의 압출성형조건을 확립하였다. 압출성형공정 조건 중 수분함량($X_1$), 스크루 회전속도($X_2$), 배럴온도($X_3$)를 독립 변수로 하고 옥수수 섬유질의 residual solid, final solution, 그리고 CFG의 수율과 각각의 SAX값을 종속 변수로 하여 화학적으로 추출 하였다. 그 결과, 수율의 경우 final solution은 EDCF가 DCF보다 낮은 경향을 보였고, residual solid와 CFG의 경우, EDCF가 DCF보다 높은 경향을 나타내었다. SAX값은 모든 조건의 EDCF가 DCF보다 높은 경향을 나타냈다. 각각의 결정된 최적의 압출성형 조건에서 분석한 결과 모든 조건에서 예측값과 결과값이 유사하여 반응표면 분석의 결과가 양호한 것으로 나타났다. 이상의 연구결과에서 반응표면 분석법이 압출성형 공정에 의한 CFG의 수율과 총 SAX값의 최적화를 위한 적절한 방법 중 하나라는 것을 보여주었다.