• 제목/요약/키워드: Hollow-part

검색결과 122건 처리시간 0.033초

중공 T형상의 형단조에 관한 연구 (A Study on Die Forging of a Hollow T-shaped Part)

  • 김현수;김용조
    • 한국정밀공학회지
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    • 제21권1호
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    • pp.32-39
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    • 2004
  • Traditional forging of a hollow T-shaped part has been applied to forge a solid T-shaped product from a solid billet and then to machine the hollow in that. In a case, a hollow T-shaped part can be forged by backward-extruding from a solid billet. In this study, four types of forging were suggested for manufacture of hollow T-shaped parts. Forging simulations for each of these forging methods were carried out to investigate folding defect, metal flow pattern, effective strain, and forging loads. Experimental works were carried out to be compared with the simulation results. Here, the ratio of the thickness of the hollow tube to that of the flange was selected to investigate a forging defect like folding.

내부 구속 중공 RC 기둥의 내진성능에 관한 매개 변수 연구 (A Parametric Study on Seismic Performance of Internally Confined Hollow RC Columns)

  • 원덕희;한택희;김정훈;최준호;강영종
    • 복합신소재구조학회 논문집
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    • 제3권2호
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    • pp.28-35
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    • 2012
  • Recently, there is to increase interest in seismic performance of piers. Hollow section is applied to increasing the seismic performance of piers. However, hollow RC pier becomes the biaixial confining state because hollow part is not confined. The pier is developed brittle failure from inner face in hollow part. A tube is inserted in hollow part to become the weakness. This is ICH RC(Internally Confined Hollow RC) pier. This pier is enhanced stiffness, strength, and ductility by core concrete has triaxial confining stress. In this paper is researched about parameters effect the seismic performance. Parameters are hollow ratio, transverse reinforcement, longitudinal reinforcement, and concrete strength.

플랜지형 중공 스핀들의 복합단조 공정설계를 위한 유한요소 시뮬레이션 (Finite Element Simulation for Design of Compound Forging Process for a Hollow Flanged Spindle)

  • 김용조
    • 한국기계가공학회지
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    • 제9권3호
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    • pp.69-75
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    • 2010
  • A hollow flanged spindle is generally used for the assembly of the driving shaft in some vehicles. This part has conventionally been manufactured by both hot forging and machining process, in which case a circular billet is hot-forged into a flanged spindle blank and then its central part is machined for hollow. Therefore, the development of a new forming technology without further machining processes has strongly been in demand. In this study, a new compound forging process of the hollow flanged spindle was proposed through the finite element simulation. By the proposed compound forging process, both extruding of the spindle body part and piercing for the hollow inside it can be performed at the same time. Metal flow patterns, forging defects and forging forces were investigated through the finite element simulation results.

중공품 성형시 삼중관의 액압성형성에 미치는 압력경로의 영향 (Effect of Loading Path on the Hydroformability of a Three-layered Tube for Fabrication of a Hollow Part)

  • 한상욱;김상윤;주병돈;문영훈
    • 소성∙가공
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    • 제22권1호
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    • pp.17-22
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    • 2013
  • Tube hydroforming is a technology that utilizes hydraulic pressure to form a tube into desired shapes inside die cavities. Due to its advantages, such as weight reduction, increased strength, improved quality, and reduced tooling cost, single-layered tube hydroforming is widely used in industry. However in some special applications, it is necessary to produce multi-layered tubular components which have corrosion resistance, thermal resistance, conductivity, and abrasion resistance. In this study, a hollow forming process to fabricate a part from multi-layered tubes for structural purposes is proposed. To accomplish a successful hydroforming process, an analytical model that predicts optimal load path for various parameters such as tube material properties, thickness of tubes, diameter of holes and the number of holes was developed. Tubular hydroforming experiments to fabricate a hollow part were performed and the optimal loading path developed by the analytical model was successfully verified. The results show that the proposed hydroforming process can effectively produce hollow parts with multi-layered tube without defects such as wrinkling or fracture.

영역분할에 의한 격자세분화기법을 사용한 철도차량 마루부재 압출공정의 3차원 유한요소해석 (Three-Dimensional Finite Element Analysis for Hollow Section Extrusion of the Underframe of a Railroad Vehicle Using Mismatching Refinement with Domain Decomposition)

  • 박근;이영규;양동열;이동헌
    • 소성∙가공
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    • 제9권4호
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    • pp.362-371
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    • 2000
  • In order to reduce weight of a high-speed railroad vehicle, the main body has been manufactured by hollow section extrusion using aluminum alloys. A porthole die has utilized for the hollow section extrusion process, which causes complicated die geometry and flow characteristics. Design of porthole die is very difficult due to such a complexity. The three-dimensional finite element analysis for hollow section is also an arduous job from the viewpoint of appropriate mesh construction and tremendous computation time. In the present work, mismatching refinement, an efficient domain decomposition method with different mesh density for each subdomain, is implemented for the analysis of the hollow section extrusion process. In addition, a modified grid-based approach with the surface element layer is utilized lot three-dimensional mesh generation of a complicated shape with hexahedral elements. The effects of porthole design are discussed through the simulation for extrusion of an underframe part of a railroad vehicle. An experiment has also been carried out for the comparison. Comparing the velocity distribution at the outlet with the thickness variation of the extruded part, it is concluded that the analysis results can provide reliable measures whether the die design is acceptable to obtain uniform part thickness. The analysis results are then successfully reflected on the industrial porthole die design.

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The Application of TiO2 Hollow Spheres on Dye-sensitized Solar Cells

  • Cho, H. J.;Jung, D.
    • Bulletin of the Korean Chemical Society
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    • 제32권12호
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    • pp.4382-4386
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    • 2011
  • $TiO_2$ hollow spheres were fabricated by using $SiO_2$ as an inorganic template. Spherical $SiO_2$ particles were coated by $TiO_2$ through the nucleation process, and then the core $SiO_2$ part was eliminated by using HF solution. Finally, $TiO_2$ hollow spheres were obtained. The size of the $TiO_2$ hollow spheres was about 300-400 nm and the thickness of the hollow wall was about 20-30 nm. The hollow has several holes whose diameters were within 100-200 nm. Dye-sensitized solar cells fabricated by using the $TiO_2$ hollow spheres were characterized. The solar conversion efficiency of the cell was 8.45% when $TiO_2$ hollow spheres were used as a scattering material, while it was 4.59% when $TiO_2$ hollow spheres were used as a normal electrode material.

내부 구속 중공 CFT 교각의 내진성능에 대한 매개변수 연구 (Parametric Study on Seismic Performance of Internally Confined Hollow CFT Column)

  • 염응준;김현종;한택희;강영종
    • 한국방재학회 논문집
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    • 제8권1호
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    • pp.15-21
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    • 2008
  • 내부 구속 중공 CFT(ICH-CFT) 기둥은 콘크리트의 양쪽(중공부와 외부)에 두 개의 강관이 삽입된 형태이다. 외부 강관과 내부 장관은 강관과 중공 부분으로 인하여 좋은 내진 성능과 연성을 발휘하며, 또한 에너지 흡수도 하는 기능을 가지고 있다. 그러므로 본 교각 형태의 실용성을 위한 연구가 필요하다고 할 수 있다. 본 논문에서는 ICH-CFT 기둥의 실용적인 설계를 목적으로, 내진성능에 대한 매개변수 연구를 실시하였다. 매개변수는 교각의 지름과 중공비 그리고 같은 모멘트 성능을 발휘하는 장관의 두께이다. 또한 경제성에 따른 연성도 평가와 CFT기둥과의 비교를 통하여 좀 더 실용적인 평가를 하고자 하였다. 특히, 중공비와 외부강관 두께에 따라 내진성능이 차이를 보였으며, ICH-CFT 교각의 외부강관의 두께에 따른 경제적인 중공비를 제시하였다.

Thixoforging에 의한 중공형 금속복합재료 부품의 기계적 특성 (Mechanical Properties for Hollow Shape Part of Metal Matrix Composites by Thixoforging)

  • 허재찬;이승후;강충길
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2001년도 추계학술대회 논문집
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    • pp.281-284
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    • 2001
  • MMC was developed that had distinguished mechanical properties and light weighted. MMC has excellent mechanical properties in many ways in automotive industrial, and get into the spotlight as a light materials substituted for iron and steel. But the know-how about MMC research lack, MMC is expensive and difficult to apply the sound parts. Especially it is difficult to produce the hollow type parts composed with MMC. Therefore, hollow type parts of metal matrix composites by thixoforging process which as co-existing solidus-liquidus phase, it is very important to obtain forming condition. In this study, used materials were A357, A380, A380 $10\%$vol, and $20\%$vol SiCp, and the size of particulates were $14{\mu}m$ and $5.5{\mu}m$

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내부 구속 중공 CFT 교각의 내진성능에 대한 매개변수 연구 (Parametric Study on Seismic Performance of Internally Confined Hollow CFT Column)

  • 김현종;염응준;한택희;강영종
    • 한국방재학회:학술대회논문집
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    • 한국방재학회 2007년도 정기총회 및 학술발표대회
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    • pp.144-147
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    • 2007
  • Internally Confined Hollow-Concrete Filled Tube(ICH-CFT) column which has two tubes on both side of concrete, inner tube and outer tube perform great seismic abilities, ductility and absorption of energy, by the tubes and the hollow part. So this study does qualitative analysis about seismic capacities depending on parameters - diameter of column, hollow ratio, thickness of tubes - by moment-curvature analysis.

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Rheological Analysis in a Spinning Process of a hollow fiber membrane

  • Jang, Moon-Seog
    • 한국막학회:학술대회논문집
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    • 한국막학회 1995년도 추계 총회 및 학술발표회
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    • pp.5-9
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    • 1995
  • In the dry-jet-wet-spinning process of a hollow fiber membrane, the polymer solution is pumped into a coaxial tube, jet spinneret. The threadline emerging from the spinneret is stabilized by an internal coagulating medium(liquid or gas) as it emerges from the jet orifice. The nascent hollow thread is further stabilized in a quench bath as shown in Fig. 1. In this scheme, three mechanism of formatiota(temperature gradient, solvent evaporation, and solvent-nonsotvent exchange) can be combined. The changes which promote stabilization often play a dominant role in determining the ultimate fiber wall structure as well. Hence, in pratice, hollow fiber stabilization and development of membrane structure are commonly inseparable. However, fiber dimension(the inside diameter and wall thickness of the hollow fiber) is mainly a rheological problem and is determined by dope pumping rate, spinneret diatance from the coagulation bath, inner coagulant flow rate, and fiber draw-rate. Besides rheological phenomena play a prominent part in the final properties of the hollow fiber.

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