• Title/Summary/Keyword: Flow Forming

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Prediction and Evaluation of Drawbead Restraining Force with Finite Element Analysis (유한요소해석을 통한 드로우비드 저항력의 예측 및 평가)

  • Bae G. H.;Song J. H.;Kim S. H.;Kim D. J.;Huh H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.87-90
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    • 2005
  • The drawbead is used to control the material flow into the die and increase the forming quality during the binder wrap process and the stamping process in the sheet metal forming. Drawbead restraining force (DBRF) is controlled by geometrical parameters and influenced by process parameters such as friction coefficient and blank thickness. In order to inspect the effect of process parameters, parameter studies are performed with the variation of parameters using finite element model of drawbead which is utilized reliably for the calculation of the drawbead restraining force. Drawbead analysis is carried out with 2-D plane-strain element and 3-D shell element. After the verification of the accuracy of the drawbead model with 3-D shell element, it is utilized to the prediction and the investigation of the effect of process parameters. The result of parameter studies can be utilized to the die design in the tryout stage.

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Finite-Element Analysis of Formability in Warm Square Cup Deep Drawing of Magnesium Alloy AZ31 Sheet (마그네슘 합금 AZ31 판재의 온간 사각컵 딥드로잉 성형성의 유한요소 해석)

  • Kim Heung-Kyu;Lee Wi Ro;Hong Seok Kwan;Han Byoung Kee;Kim Jong Deok
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.122-125
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    • 2005
  • Magnesium alloys are expected to be widely used for the parts of structural and electronic applications due to their lightweight and EMI shielding characteristics. While the die casting has been mainly used to manufacture the parts from the magnesium alloys, the press forming is considered as an alternative to the die casting for saving the manufacturing cost and improving the structural strength of the magnesium alloy parts. However, the magnesium alloy has low formability at room temperature and therefore, in many cases, forming at elevated temperatures is necessary to obtain the required material flow without failure. In the present study, square cup deep drawing tests using the magnesium alloy AZ31 sheet were experimentally conducted at various elevated temperatures as well as room temperature, and the corresponding finite-element simulations, which calculated the damage evolution based on the Oyane's criterion, were conducted using the stress-strain relations from the tensile tests at various temperatures. The formability predictability by the finite-element analysis was investigated by comparing the predicted damage distributions over the deformed AZ31 sheet at elevated temperatures with the corresponding experimental deformations with failures.

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Development of the controller for peeling off the enamel and forming of deflection yoke coil (편향요크코일의 에나멜 탈피 및 통전성형을 위한 탈피통전기의 개발)

  • Jeong, Soo-Hoa;Yun, Jong-Soon;Kwon, Woo-Hyun
    • Proceedings of the KIEE Conference
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    • 1995.07a
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    • pp.202-205
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    • 1995
  • Developed controller is the part of deflection yoke winding machine which controls the power to form the deflection yoke coil into desired shape after winding. So as to form the deflection yoke coil, it is needed to melt the bonding material which is spreaded on the coil. The heat melt the bonding material which is produced by flowing the current through the winded coil. Therefore, at first it is needed to peel off the enamel from the winded coil so as to flow the current, and then supply the power to produce the heat which form the winded coil into desired shape. Naturally developed controller is composed of the peeling part and the conduction and forming part. All of them consist of the inverter structure and control the output current. The peeling is achieved by low voltage and high AC current, the conduction and forming is by DC current. Developed controller also has a function that detect the resistance of the deflection yoke coil to prevent the damage of the load which is produced by poor peeling.

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Evaluation of the Temperature Dependent Flow Stress Model for Thermoplastic Fiber Metal Laminates (열가소성 섬유금속적층판의 온도를 고려한 유동응력 예측에 대한 연구)

  • Park, E.T.;Lee, B.E.;Kang, D.S.;Kim, J.;Kang, B.S.;Song, W.J.
    • Transactions of Materials Processing
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    • v.24 no.1
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    • pp.52-61
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    • 2015
  • Evaluation of the elevated temperature flow stress for thermoplastic fiber metal laminates(TFMLs) sheet, comprised of two aluminum sheets in the exterior layers and a self-reinforced polypropylene(SRPP) in the interior layer, was conducted. The flow stress as a function of temperature should be evaluated prior to the actual forming of these materials. The flow stress can be obtained experimentally by uniaxial tensile tests or analytically by deriving a flow stress model. However, the flow stress curve of TFMLs cannot be predicted properly by existing flow stress models because the deformation with temperature of these types of materials is different from that of a generic pure metallic material. Therefore, the flow stress model, which includes the effect of the temperature, should be carefully identified. In the current study, the flow stress of TFMLs were first predicted by using existing flow stress models such as Hollomon, Ludwik, and Johnson-Cook models. It is noted that these existing models could not effectively predict the flow stress. Flow stress models such as the modified Hollomon and modified Ludwik model were proposed with respect to temperatures of $23^{\circ}C$, $60^{\circ}C$, $90^{\circ}C$, $120^{\circ}C$. Then the stress-strain curves, which were predicted using the proposed flow stress models, were compared to the stress-strain curves obtained from experiments. It is confirmed that the proposed flow stress models can predict properly the temperature dependent flow stress of TFMLs.

Flow Visualization of Oscillation Characteristics of Liquid and Vapor Flow in the Oscillating Capillary Tube Heat Pipe

  • Kim, Jong-Soo;Kim, Ju-Won;Jung, Hyun-Seok
    • Journal of Mechanical Science and Technology
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    • v.17 no.10
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    • pp.1507-1519
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    • 2003
  • The two-phase flow patterns for both non-loop and loop type oscillating capillary tube heat pipes (OCHPs) were presented in this study. The detailed flow patterns were recorded by a high-speed digital camera for each experimental condition to understand exactly the operation mechanism of the OCHP. The design and operation conditions of the OCHP such as turn number, working fluid, and heat flux were varied. The experimental results showed that the representative flow pattern in the evaporating section of the OCHP was the oscillation of liquid slugs and vapor plugs based on the generation and growth of bubbles by nucleate boiling. As the oscillation of liquid slugs and vapor plugs was very speedy, the flow pattern changed from the capillary slug flow to a pseudo slug flow near the annular flow. The flow of short vapor-liquid slug-train units was the flow pattern in the adiabatic section. In the condensing section, it was the oscillation of liquid slugs and vapor plugs and the circulation of working fluid. The oscillation flow in the loop type OCHP was more active than that in the non-loop type OCHP due to the circulation of working fluid in the OCHP. When the turn number of the OCHP was increased, the oscillation and circulation of working fluid was more active as well as forming the oscillation wave of long liquid slugs and vapor plugs in the OCHP. The oscillation flow of R-142b as the working fluid was more active than that of ethanol and the high efficiency of the heat transfer performance of R -142b was achieved.

FE Analysis of Extrusion Process for Heat sink (방열판 직접압출 공정의 유한요소해석)

  • 이정민;김병민;조형호
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.313-317
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    • 2003
  • Porthole die extrusion is the method which put the billet in the container and push it between die hole by ram. This method make it possible that product manufacture which have complex shape of area with excellent induction of area, in addition that this is economical. So this method is used as the basic manufacturing method of many industrial materials. The subject of this research is the forming technology development of heat sink which is being produced by extrusion process in my country. Flow condition of extrusion for heat sink, and metal flow of billet in the die are estimated by the means of rigid-plasticity finite element method.

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The Effect of Swirl Flow on Combustion Characteristics in a Marine Diesel Engine (박용 디젤기관에서 스월유동이 연소특성에 미치는 영향)

  • 김병현;박권하;이상수;성낙원
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.2
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    • pp.38-49
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    • 2000
  • A diesel engine has been studied for many years to improve fuel economy and to reduce emissions as important factors governing the emission performance of diesel engines. This study addresses to swirl effects on combustion characteristics in a large diesel engine. The transport equations of flows and chemical reactions are given for fully compressible fluid. The simulations have been done for compression and expansion strokes and the results are given at several crank angles which are the angles at just before injection start, TDC, ATDC 90 and just before exhaust valve open. The results show that the strength of the swirl flow makes many effects on burning fuel and forming emissions.

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The influence of Mixture Flow and the Ignition Conditions on the Initial Flame Propagation Characteristics (혼합기의 유동 및 점화조건에 따른 초기화염의 전파특성)

  • Kim, Jin-Young;Lee, Joong-Soon;Ha, Jong-Yul
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.6
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    • pp.57-64
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    • 1999
  • Initial flame development and propagation were visualized under the new ignition system developed to estimate the effects of ignition characteristics on the engine performance in a port injection SI engine. Effects of intake air flow characteristics were also investigated by three different kinds of the swirl control valve. Experiments were performed in an optical single cylinder engine modified form a commercial engine. Flame images were captured through the quartz window mounted in the piston by the high speed video camera and analyzed to compare initial flame development. Results show that IMEP tends to rise slightly as the ignition duration gets longer. The direction of flame propagation is decisively governed by the in-cylinder flow motion. Every flame grows toward the exhaust valve forming a kind of turbulent flame. Initial flame propaagation characteristics are very similar to ones analyzed form pressure data.

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A Study on the spatial Layout of Modern Settlements in Hwangjon Korea (한국 근대 주거 및 취락의 공간적 질서체계에 관한 연구)

  • 이현희
    • Korean Institute of Interior Design Journal
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    • no.13
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    • pp.197-202
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    • 1997
  • In this study, we surveyed historical housing settlements of Hwangjon in Bonghwa-a clan village in Youngnam district which was formed in the Chosun Dynasty. We observe the relationships among the spatial layout of clan villages, the water flows and the family hierarchies as follows; (1) when a clan village was initially formed, the water flow, which is the phylosophical foundation of Poong Soo, was the most important factor for determining the original location; (2) as villages prosper, the water flow and the family hierarchy still played an important role in determining the following geological locations; (3) in modern age, however, the water flow and the family hierarchy lost the role in detrmining the geological locations; (4) consequently, in present days, each household becomes isolated from the village. Reflecting on these observations, for village to be maintained, we conclude that we need novel practical and cohesive village forming drives that can replace the water flows and the family hierarchy in the past.

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Optimal Configuration of a Liquid Ramjet Combustor using PIV Method (PIV측정을 통한 램제트 연소기의 최적 형상)

  • 손창현;김규남;문수연;이충원
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2002.04a
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    • pp.46-49
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    • 2002
  • Three-dimensional flow characteristics in a liquid fuel ramjet combustor were investigated using the PIV method. The combustor has two rectangular inlets that loin a 90-degree angle each other. Three cases of test combustors are made in which those inlet angles are 30 degree, 45degree and 60 degree. The experiments were performed in a water tunnel test with the same Reynolds number as Mach 0.3 at the inlet. PIV software was developed to measure the characteristics of the flow field in the combustor. Accuracy of the developed PIV program was verified with a rotating disk experiment and standard data. The characteristics of the internal flows of the combustor are large swirling flows which appear symmetric with respect to the symmetric section. This is attributed to the fact that the flows introduced from the right and left intakes collide with each other, thus forming symmetrically large vortices. A large and complex three-dimensional recirculating flow was measured behind the intakes. An inlet angle of 30 degrees is the most suitable angle as a frame he]der in the performed experimental ranges.

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