• 제목/요약/키워드: 반용융 재료

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Thixoforming을 위한 금속복합재료의 재가열 공정 (Reheating Process of Metal Matrix Composite for Thixoforming)

  • 안성수;강충길;조형호
    • Composites Research
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    • 제13권4호
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    • pp.19-32
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    • 2000
  • 본 논문은 강화입자가 균일하게 분산된 금속 복합재료의 제조와 반용융 성형을 위한 재가열에 관한 연구결과이다. 강화재 크기의 종류에 따른 금속복합재료를 제조하기 위하여 전자기식 교반과 기계식 교반을 동시에 이용한 복합 교반법을 사용하였다. 복합 교반법에 의하여 제조된 금속복합재료의 분산 상태를 조사하였다. 복합재료를 제조하기 위한 전자기식 교반법과 기계식 교반법을 겸용으로 한 공정이 소개되었다. 금속복합재료의 반용융성형을 위해서, 금속복합재료의 빌렛과 코일표면사이의 길이, 코일의 지름과 빌렛사이의 길이로 구성된 함수로 최적의 코일을 설계하여 빌렛을 재가열하였다. 복합재료의 반용융 성형시에 필요한 재가열 공정 인자인 가열시간과 온도변화의 관계를 조사하였다. 재가열중 강화재의 분산상태가 온도변화에 미치는 영향에 대하여 검토하였다.

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상계법에 의한 반용융 재료의 항복과 압축거동 (Yield and Compression Behavior of Semi-Solid Materials by Upper-Bound Method)

  • 최재찬;박형진;박준홍
    • 한국정밀공학회지
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    • 제15권6호
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    • pp.139-144
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    • 1998
  • In Semi-Solid Forging, it is necessary to control the forming variables accurately in order to make near-net-shape products. Generally, the defects of products may occur due to liquid segregation which can be caused by the degree of deformation and strain rate, and condition of friction in Semi-Solid Forging, where the segregation is to be predicted by flow analysis. This paper presents the feasibility of theoretical analysis model using the new yield function for compressible P/M materials which is proposed by Doraivelu et at. to the flow analysis of the semi-solid dendritic Sn-15%Pb alloys instead of adopting the yield criterion of Shima and Oyane which is used by Charreyron and Flemings. The simple compression process is taken into consideration as the model to confirm the usefulness of the adopted yield function. The distribution of the liquid fraction at various strains and strain rates in radial direction, and the influence of friction are estimated by upper-bound method.

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유한요소법과 상계법에 의한 반용융 재료의 항복거동 연구 (Study on Yield Behavior of Semi-Solid Material by Finite Element Method and Upper-Bound Method)

  • 최재찬;박준홍;김병민
    • 한국정밀공학회지
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    • 제16권9호
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    • pp.89-95
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    • 1999
  • The compression behavior of semi-solid materials in studied from a viewpoint of yield criteria and analysis methods. To describe the behavior of materials in semi-solid state, several theories have been proposed by extending the concept of plasticity of porous compressible materials. in the present work, the upper-bound method and the finite element method are used to model the simple compression process using yield criteria of Kuhn and Doraivelu. Segregation between solid and liquid which cause defect of product is analysed for Sn-15%Pb alloy is compared with the experimental result of Charreyron et al..

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반용융 재료의 압출공정에 관한 유한요소해석 (Finite Element Analysis of Extrusion Process in Semi-Solid State)

  • 황재호;고대철;민규식;김병민;최재찬
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 고액공존금속의 성형기술 심포지엄
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    • pp.5-15
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    • 1997
  • It is the objective of this study that by conducting the serni-solid extrusion using A12024, the effect of various process variables on the quality of extruded product and extrusion force is understood. The results of experiment are compared with those of finite element simulation in order to verify the effectiveness of the developed FE-simulation code. In order to simulate densification in the deformation of serni-solid material, the semi-solid material is assumed to be composed of solid region as porous skeleton following compressible visco-plastic model and liquid region following Darcy's equation for the liquid flow saturated in the interstitial space. Then the flow and deformation of the semi-solid alloy are analyzed by coupling the deformation of the porous skeleton and the flow of the eutectic liquid. It is assumed that initial solid fraction is homogeneous. Yield and plastic potential function presented by Kuhn and constitutive model developed by Gunasekera are used for solid skeleton.

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반용융 재료의 압출공정에 관한 유한요소 해석 (Finite Element Analysis of Extrusion Process in Semi-Solid State)

  • 황재호;고대철;민규식;김병민;최재찬
    • 소성∙가공
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    • 제7권4호
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    • pp.364-374
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    • 1998
  • It is the objective of this study to analyze the effect of various process variables on the quality of extruded product and extrusion force for semi-solid extrusion of Al2024 with solid phase structure of globular type by the finite element method. Process variables are initial solid fraction, ram speed, semi-angle of die, and reduction in area. The results of experiment are compared with those of simulation in order to verify the usefulness of the developed finite element program. The flow and deformation of semi-solid alloy are analyzed by coupling by coupling the deformation of porous skeleton and the flow of liquid phase. It is also assumed that initial solid fraction is homogeneous.

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응고현상을 고려한 반용융 알루미늄재료의 단조공정에 관한 충전해석 (A Filling Analysis on Forging Process of Semi-Solid Aluminum Materials Considering Solidification Phenomena)

  • 강충길;최진석;강동우
    • 소성∙가공
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    • 제5권3호
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    • pp.239-255
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    • 1996
  • A new forming technology has been developed to fabricate near-net shape products using light metal. A semi-solid forming technology has some advantages compared with the conventional forming processes such as die casting squeeze casting and hot/cold forging. In this study the numerical analysis of semi-solid filling for a straight die shape and orifice die shape in gate pattern is studied on semi-solid materials(SSM) of solid fraction fs =30% in A356 aluminum alloy. The finite difference program of Navier-Stokes equation coupled with heat transfer and solidification has been developed to predict a filling pattern and the temperature distribution of SSM. The programdeveloped in this study gives die filling patterns of SSM and final solidifica-tion region.

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반용융 재료의 변형거동에 대한 변형률 속도의 영향 (Effect of strain-rate on deformation behavior of semi-solid material)

  • 황재호;고대철;최재찬
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1997년도 춘계학술대회 논문집
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    • pp.777-781
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    • 1997
  • In this study, the effect of strain-rate and inital solid fraction on the deformation behaviour of semi-solid material is investigated, when semi-solid forging is performed by the process of closed-die compression using A356 alloy of which the above results can be practically applied for industrical purpose. In order to simulate densification in the deformation of semi-solid material, the semi-solid material is assumed to be composed of solid region following rigid visco-plastic material, the liquid region following Darcy's law for the liquid flow saturated in the interstitial space. Simulation results of closed-die compression and simple upsetting under different strain-rate and initial solid fraction are compared.

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유도가열을 고려한 반용융 재료의 성형공정에 관한 유한요소 해석 (Finite Element Analysis for Forming Process of Semi-Solid Material Considering Induction Heating)

  • Park, W.D.;Ko, D.C.;Kim, B.M.;Park, J.C.
    • 한국정밀공학회지
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    • 제14권8호
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    • pp.82-91
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    • 1997
  • The major objective of this study is to establish analytical technique in order to analyze the behaviour of semi-solid material considering induction heating of the billet. Induction heating process is analyzed by using commerical finite element software. ANSYS. The finite element program, SFAC2D, for the simulation of deformation in semi-solid state is developed in the present study. The semi-solid behaviour is described by a viscoplastic model for the solid phase, and by the Darcy's law for the liquid flow. Simple compression and closed-die compression process considering induction heating are analyzed, and also it is found that the distribution of initial solid fraction of the billet has an important effect on deformation behaviour of semi-solid material. In order to verify the effectiveness of proposed analytical technique the simulation result is compared with experimental result.

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유도가열을 고려한 반용융 재료의 성형공정에 관한 유한요소 시뮬레이션 (A FE-simulation for forming process of semi-solid material considering induction heating)

  • 최원도;고대철;김병민;최재찬
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1996년도 추계학술대회 논문집
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    • pp.110-114
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    • 1996
  • The objective of this study is to consider the induction heating process and to develop the finite element program to analyze the behaviour of semi-solid materials. The semi-solid material is assumed to be composed of solid region as rigid visco-plastic model and liquid region following Darcy's law. Induction heating process is analyzed using finite element software, ANSYS, and also the behaviour of a semi-solid material considering induction heating is analyzed using developed finite element program.

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