• Title/Summary/Keyword: near-net shape

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Finite Element Analysis of Compression Holding Step Considering Solidification for Semi-Solid Forging (반용융 단조에서 응고 현상을 고려한 가압유지 단계의 유한요소해석)

  • 최재찬;박형진;조해용
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.597-601
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    • 1997
  • The technology of Semi-Solid Forging(SSF) has been actively developed to fabricate near-net shape products using light and hardly formable materials. Generally, the SSF process is composed of slug heating,forming,compression holding and ejecting step. After forming step in SSF, the slug is comperssed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. This paper presents the analysis of temperature,solid fraction and shrinkage at compression holding step for a cylindrical slug,then predicts the solidification time to obtain the final shaped part. Enthalpy-based finite element analysis is performed to solve the heat transfer problem considering phase change in solidification.

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Forging Process with Al6061 Alloy Rheology Material by Electromagnetic Stirring System (전자교반을 응용한 Al6061 레오로지 소재의 단조공정)

  • Kang, S.S.;Oh, S.W.;Kang, C.G.
    • Transactions of Materials Processing
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    • v.16 no.6
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    • pp.443-446
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    • 2007
  • The semi-solid process has been developed near net-shape components for kinds of methods. Thixo-forming with reheating prepared billet and rheo-forming with cooled melt until semi-solid state. Material is applied electromagnetic stirring system to slurry with aluminum 6061 alloy. An experiment has variation factors which are pressure, solid-fraction, stirring current and stirring time. The mechanical properties are compared to forge sample with to apply heat treatment T6. This study is researched function a virtual pressure and fine shape zone. Optimum pressure is found to prevent defect of porosity.

Process Sequence Design in Cold Forging of Constant Velocity Joint Housing (등속조인트 하우징의 냉간단조 공정설계)

  • 이진희;강범수;김병민
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.9
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    • pp.2234-2244
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    • 1994
  • A process sequence of multi-operation cold forging for actual application in industry is designed with the rigid-plastic finite element method to form a constant velocity joint housing(CVJ housing). The material flow during the CVJ housing forming is axisymmetric until the final forging process for forming of ball grooves. This study treats the deformation as an axisymmetric case. The main objective of the process sequence design is to obtain preforms which satisfy the design criteria of near-net-shape product requiring less machining after forming. The process sequence design also investigates velocity distributions, effective strain distributions and forging loads, which are useful information in the real process design.

Die design for the cold forging spur gears

  • Kwon, Hyuk-Hong
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.1
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    • pp.120-126
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    • 2002
  • The near net shape forging of gears offers significant technical and economic advantages ever other forms of manufacture. These potential benefits can however only be realized by careful die design. This paper describes a computer-based methodology fur achieving this. A Visual-BASIC program has been developed on a rule based system that enables optimal design of the dies taking into account the elastic deflections generated in shrink-fitting the die inserts and that caused by the stresses generated in the forging process. The method also enables the profile of the spark erosion electrode to be determined. An example of the application to forging spur gears is given.

A Finite Element Heat Transfer Analysis with Coupling of Roll and Molten Metal in Direct Rolling Process (직접압연공정에 있어서 롤과 용탕을 연계한 유한요소 열전도해석)

  • 김영도;강충길
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.946-957
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    • 1994
  • In the steel industries, direct rolling process for production of strip from molten metal has been investigated to simplify processes, to minimize energy consumption, and to improve quality of the strip. In this study, two kinds of practicable scale cooling rollers are proposed. And heat transfer analysis of pool region and cooling roller considering flow of molten metal and roll rotation respectively using the finite element method are performed to obtain the proper initial condition and to observe cooling characteristics of cooling roller. From the results, variations of solidification final points and temperature distribution in roller are observed quantitatively according to roll rotation.

A Study on Infiltration Limits in Forming Process of Metal Matrix Composites by Squeeze Casting (용탕단조법에 의한 금속복합재료의 성형공정에 있어서 함침한계성에 관한 연구)

  • Kang, C.C.;Ku, G.S.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7
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    • pp.1751-1760
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    • 1993
  • The squeeze casting process is considered as an attractive way to form the primary product of near net shape metal matrix composites for wide use in automobile industry. To understand for infiltration limit in squeeze casting processes, the SAFFIL short fiber preform of volume fraction $10%{\sim}23%$ were fabricated by vaccum pumping and speed control press, and the optimal condition for fiber preform fabrication had been experimentally obtained. The composite materials were fabricated by forced infiltration of molten metals such as Al6061, Al7075, pure Al, AC8A, and Al2024. The infiltration distance and deformation of fiber preform are observed, and tensile strength were measured from at the room temperature.

Microstructure and Mechanical Properties of $SiC_p/6061$ Al Composites Fabricated by Indirect Squeeze Casting (간접 용탕단조법에 의하여 제조한 $SiC_p/6061$ Al 복합재료의 조직과 기계적 성질)

  • Seo, Young-Ho;Kang, Chung-Gil
    • Journal of Korea Foundry Society
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    • v.18 no.4
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    • pp.373-382
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    • 1998
  • Particulate reinforced aluminum alloys produced by indirect squeeze casting are difficult to shape by cutting or milling. Therefore near net shape forming of complex shapes is of high economic and technical interest. The complex shape products of $SiC_p/6061$ Al composites are fabricated by the melt-stirring and indirect squeeze casting process. The mold temperatures are $200^{\circ}C$ and $300^{\circ}C$ and applied pressures are 70, 100, and 130 MPa. The volume fractions of the reinforcements are in the range of 5 vol% to 15 vol%. The reinforcement dispersion state are observed using on optical microscope. By employing observed results systematically a correlation is demonstrated among the microstructure, particles behavior, mechanical properties and processing parameters for an optimum melt-stirring(compocasting) and indirect squeeze casting process of MMCs. A procedure to establish the optimum squeeze casting of Al-MMCs is proposed.

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Front Tracking Finite Element Analysis of Heat Transfer in Spray Forming Process (경계추적 유한요소법을 이용한 분무성형공정에서의 열전달 해석)

  • 장동훈;강신일
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.148-152
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    • 1997
  • A numerical method is presented to predict and analyze the shape and the temperature history of a growing billet produced form the "spray forming" which is a fairly new near net-shape manufacturing process. It is important to understand the mechanism of billet growing and the cooling history of the spray deposited body, because one can obtain a billet with the desired final shape without secondary operations by accurate control of the billet shape and, moreover, growing velocity together with the cooling rate define the microstructure of the final formed product. In the present study, a theoretical model is first established to predict the shape of the billet and next the transient axisymmetric heat conduction problem with growing domain is solved using the so called "front tracking finite element technique".ent technique".uot;.

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Manufacture of 3D Textile Preform and Study on Mechanical Properties of Composites (3D Textile 프리폼 제조 및 복합재료 기계적 특성 연구)

  • Jo, Kwang-Hoon;Klapper, Vinzenz;Kim, Hyeon-Woo;Lee, Jeong-Woon;Han, Joong-Won;Byun, Joon-Hyung;Joe, Chee-Ryong
    • Composites Research
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    • v.32 no.1
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    • pp.65-70
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    • 2019
  • The aircraft composites wing parts are usually integrated with adhesive or fastener. These laminated composites have weak interlaminar strength, which can lead to delamination. In order to compensate the disadvantages of laminated composites, it is possible to improve the strength, durability, shock and fatigue resistance by reinforcing the fiber in the thickness direction. In addition, using a single structure near-net-shape saves the manufacturing time and the number of fasteners, thus can reduce the overall cost of the composite parts. In this study, compression test, tensile test and open-hole tensile test are carried out for three structural architecture of 3D (three-dimensional) textile preforms: orthogonal(ORT), layer-to-layer(LTL) and through-the-thickness(TTT) patterns. Among these, the orthogonal textile composite shows the highest Young's modulus and strength in tensile and compression. The notch sensitivity of the orthogonal textile composite was the smallest as compared with UD (unidirectional) and 2D (two-dimensional) fabric laminates.

Axial Pressing Method Using Pulse Magnetizing Field for the Preparation of Nd-Ee-B Sintered Magnets (펄스자장을 이용한 고이방화 Nd-Fe-B자석의 종축자장성형방법)

  • Kim, Dong-Hwan;Kang, Byung-Kil;Jang, Dong-Youl;Kim, Andrew S.;Kim, Sang-Myun;Jang, T.S.
    • Journal of the Korean Magnetics Society
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    • v.13 no.4
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    • pp.182-186
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    • 2003
  • A new axial pressing method using pulse magnetizing field was studied to improve the remanence of Nd-Fe-B sintered magnets. In order to make near-net shape green compacts of butterfly, disk, or coin magnets, conventional axial-type pressing has been normally used. However, compared to the transverse-type pressing, it is not possible to obtain higher remanence by this method because the magnetic alignment of powder begins to deteriorate when the density of green compacts increases over a critical value. On the other hand, we found that an axial pressing under pulse magnetizing field was very effective to increase the degree of magnetic alignment of powder, yielding remanences even higher than those obtained by the transverse pressing. In this study, it was revealed that appropriate tapping density and how to apply pulse magnetic held were important to improve the grain alignment and thus remanence of Nd-Fe-B sintered magnet.