• 제목/요약/키워드: Semi-solid phase

검색결과 73건 처리시간 0.031초

알루미늄재료의 Rheo-forming을 위한 성형공정해석 (Process Analysis for Rheo-Forming of Aluminum Materials)

  • 서판기;정영진;정경원;강충길
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2001년도 춘계학술대회 논문집
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    • pp.124-128
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    • 2001
  • Two-dimensional solidification analysis during rheology forming process of semi-solid aluminum ahoy has been studied Two-phase fluid flow model to investigate the velocity field and temperature distribution is proposed. The unposed mathematical model is applied to the die shape of the two type. To calculate the velocities and temperature fields during rheology forming process, the each governing equation correspondent to the liquid and solid region are adapted. Theoretical model on the basis of the two-phase flow model is the mixture rule of solid and liquid phases. This approach is based on the liquid and solid viscosity.

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결정립 제어 소재의 레오로지 유동이 고상입자의 거동에 미치는 영향 (The Effect of Rheology Flow with Grain Size Controlled Material on Solid Particles Behavior)

  • 정용식;서판기;강충길
    • 소성∙가공
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    • 제14권4호
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    • pp.351-359
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    • 2005
  • The semi-solid processing is now becoming of great interest for the production of various parts by pressure die casting. Also, the rheo-casting has been substituted for thixo-casting, because the rheo-casting can control the solid particles to globular and non-dendritic solid phase. In the rheo-casting process, the important thing is to control the solid particles behavior in semi-solid materials. So in this paper, to control solid particles behavior in semi-solid materials, we experimented about the die filling tests during the semi-solid die casting in 0.3, 0.4, 0.5 and 0, 6 solid fraction. The die filling in semi-solid die casting were simulated by MAGMA soft/thixo module. By the die filling tests and computer simulation, the effect of solid particles behavior in rheology flow had been investigated.

결정립 제어소재의 레오로지 유동이 고상입자의 거동에 미치는 영향 (The Effect of Rheology flow with Grain Size Controlled Material on Solid Particles Behavior)

  • 정용식;서판기;강충길
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2004년도 추계학술대회 논문집
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    • pp.664-667
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    • 2004
  • The semi-solid processing is now becoming of great interest for the production of various parts by pressure die casting. Also, the rheolory casting has been substituted for thixo casting, because the rheology casting can control the solid particles to globular and non-dendritic solid phase. In the rheology casting process, the important thing is to control the solid particles behavior in semi-solid materials. So in this paper, to control solid particles behavior in semi-solid materials, we experimented about the die filling during the semi-solid die casting in 0.3, 0.4, 0.5, 0,6 solid fraction. The die filling in semi-solid die casting were simulated by MAGMAsoft/thixo module. By the die filling tests and computer simulation, the effect of solid particles behavior in rheology flow had been investigated.

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Mg합금의 반용융가압주조시 주조조건에 의한 금형충전성 및 유동성 변화 (A Study on Mold Filling and Fluidity of Mg Alloy in Thixocasting)

  • 정운재;김기태;홍준표
    • 한국주조공학회지
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    • 제15권2호
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    • pp.184-193
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    • 1995
  • Effects of process parameters during thixocasting, such as solid volume fraction, mold temperature and extrusion ratio, on the mold filling behaviour and fluidity of Mg alloy(AZ91D) have been investigated. The semi-solid ingot held for 60 minutes at the semi-solid temperature range did not contain the equilibrium volume fraction of solid as expected from the phase diagram. Therefore, in order to obtain the desired solid fractions, and to suppress the exaggerated grain growth during heating, it was required to heat the ingot rapidly up to the temperature $10^{\circ}C$ higher than the semi-solid temperature suggested from the phase diagram for a specific volume fraction of solid. The experimental results show that mold filling behaviour and fluidity can be improved with the use of the higher mold temperature and the lower volume fraction of solid, but remain nearly unaffected by the change of extrusion ratio.

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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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레이저를 이용한 균일 금속액적 적층에 관한 연구 (A Study on the Uniform Metal-Droplet Deposition Using Laser)

  • 유성복;김용욱;양영수
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 추계학술대회 논문집
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    • pp.667-670
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    • 2002
  • Uniform metal-droplet deposition using laser is analyzed. Using the variation principle and modeling the semi-solid phase as a non-Netwonian slurry, this model can greatly save the computational expenses that conventional numerical procedures have suffered from. The simulation results revealed that the developed model could reasonably describe the collision behavior of molten metal with solid surface. Simulations were made with variation of the falling distance and time.

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혼합이론에 근거한 반용융 재료의 고상률 분포 예측 (Prediction of Distribution of Solid Volume Fraction in Semi-Solid Materials Based on Mixture Theory)

  • 윤종훈;김낙수;임용택
    • 소성∙가공
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    • 제8권4호
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    • pp.399-406
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    • 1999
  • It is more appropriate to treat that the semi-solid mixture as a single phase material that obeys incompressibility in the global sense and to analyze the liquid flow only locally than the approach based on compressible yield criteria. In the present study, a numerical algorithm of updating the solid volume fraction based on mixture theory has been developed. Finite element analysis of simple upsetting was carried out using the proposed algorithm to investigate the degree of macro-segregation according to friction conditions and compressive strain rates under the isothermal condition. The simulation results were compared to experimental results available in reference to test the validity of the currently proposed algorithm. Since the comparison results show a good agreement it is construed that the proposed algorithm can contribute to the development of numerical analysis of determining the solid volume fraction semi-solid processing.

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반응용재료의 압축거동 및 액상의 유동을 고려한 유한요소해석 (A Compression Behavior of Semi-Solid Material and Finite Element Analysis Considering Flow of Liquid Phase)

  • 강충길;윤종훈
    • 대한기계학회논문집A
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    • 제20권12호
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    • pp.3715-3727
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    • 1996
  • Compression behavior of semi-solid aluminum alloys with controlled solid fractions was investigated in the present study. The stress and strain relationships were obtained from the compression test. Variations of the solid fraction distribution and the material behaviour were investigated for various friction coeffieiants and die speedsd. For a finite element analysis, the semi-solid material was described by a compressible regid viscoplastic model for the solid region and darcy's law for the liquid region. The computed results were compared with experimental data for the validity of the yield criteria.

강-열점소성 유한요소법을 이용한 반용융단조시 성형인자들의 영향에 관한 연구 (A Study on Effect of Forming Parameters in Semi-Solid Forging by Rigid-Thermoviscoplastic Finite Element Method)

  • 윤종훈;김낙수;임용택;이준두
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1998년도 춘계학술대회논문집
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    • pp.179-184
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    • 1998
  • Semi-solid forging can be applied in industry only with enough knowledge of the effects of the forming parameters related with the process and their exact control which can be obtained by empirical or numerical methods. In the current study, the effects of process variables on semi-solid forging are discussed based on mainly numerical results. Die preheating temperature, initial solid fraction of the workpiece, and die velocity were selected as process variables, and numerical analyses using a rigid-thermoviscoplastic finite element approach that considered the release of latent heat due to phase change were carried out. In the analyses, a proposed flow stress material characterization and a solid fraction updating algorithm were employed. The obtained results from numerical analysis are discussed and are compared with some experimental observations.

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반용융 단조품의 제조 (Manufacturing of Product by Semi-Solid Forging)

  • 박형진;강충길;김병민;최재찬
    • 한국정밀공학회지
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    • 제16권6호
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    • pp.45-51
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    • 1999
  • The semi-solid forging is a new forging technology in which the billet is heated to the semi-solid state coexisting liquid and solid phase for making globular microstructure and subsequently formed. As the semi-solid forging is compared with conventional casting such as die casting and squeeze casting for the characteristics of its process, the product without inner defects such as gas porosity and segregation can be obtained and its microstructure is globular grain. Simutaneously, its mechanical properties are improved by globular microstructure and the lower temperature of the slug causes the cycle time of manufacturing to be shortened and the die life to be lengthened. As it is compared with conventional cold and hot forging, it is possible to minimize the equipment of production owing to a lower forming load and reduce the number of process by a followed treatment for complex shaped product. Therefore it is needed to confirm the quality of a semi-solid forged product by defining its characteristics quantitatively under these advantages. This paper investigates the formability of a master cylinder by its forming variables. And the microstructural characteristics and mechanical property of it is also studied.

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