• Title/Summary/Keyword: Thixoforming

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A Study on Development of Program for an Automated Thixoforming Process Design (Thixoforming 공정설계 자동화를 위한 프로그램 개발에 관한 연구)

  • Kim, Nam-Seok;Jeong, Hong-Gyu;Gang, Chung-Gil
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.1
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    • pp.44-55
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    • 2001
  • The flow behavior of semi-solid materials (SSM) is required to assist the industrial application of thixoforming technology. Particularly, to reduce many lead times, many numerical analysis packages have been developed to simulate required metal forming processes. The objectives of the development of SEMI-FORM for thixoforming process design are to predict the effect of various process variables such as pressing force, die temperature, and die velocity. However, there have not been any reports which adapt these packages to the specific characteristics of SSM. SO, this paper presents an overview of the development of thixoforming simulator of SEMI-FORM. The solver and post-processor of SEMI-FORM S/W for an automated thixoforming process design with arbitrarily shaped die are composed of FORTRAN Power Station 4.0 and Visual Basic 5.0, respectively. This developing SEMI-FORM S/W would be very useful for thixoforming practitioners and engineers to select the optimal process conditions to produce automotive parts with high quality.

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Multi-Step Reheating Process of Metal Matrix Composites for Thixoforming (Thixoforming을 위한 금속 복합재료의 다단 재가열 공정)

  • 허재찬;강충길
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.180-183
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    • 1997
  • The forming process of metal matrix composites by the die casting and squeeze casting process are limited in size and dimension in term of final parts without machining. The thixoforming process for metal matrix composites has numerous advantages compared to die casting, squeeze casting and compocasting. The characteristics of thixoforming process can decrease the liquid segregation because of he improvement in fluidity in a globular microstructure state and utilizes flow without air entrapment. Therefore, in order to obtain the sound parts of metal matrix composites by using thixoforming process which as co-existing solidus-liquidus pahse, it si very important to obtain reheating condition. However, for he thixoforming process, the billet with the desired volume fraction must be heated to obtain a uniform temperature distribution over the entire cross-sectional areas. To obtain the reheating conditions of composites, the particulate reinforced metal matrix composites for thixoforming were fabricated by combined stirring process which is simultaneously performed with electro-magnetic stirring process which is simultaneously performed with electro-magnetic stirring and mechanical stirring process.

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Effect of Viscosity Variation on Flow Characteristic in Thixoforming Process of Semi-Solid Aluminium Alloys (반용융 알루미늄 합금의 Thixoforming 공정에서 점도의 변화가 유도특성에 미치는 영향)

  • 강충길;이유철
    • Transactions of Materials Processing
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    • v.8 no.2
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    • pp.188-199
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    • 1999
  • Semi-Solid Forming Process(Thixoforming, Rheocasting) is a novel forming process which has some advantages compared with conventional die casting, squeeze casting and hot/cold forging. In this study. Thixoforming process was selected as analysis processing in terms of billet handling and easiness of automation process. The Thixoforming process consists of reheating process of billet, billet handling, filling inot the die cavity and solidification of SSM part. In filling process, two rheology models which were Newtonian and Non-Nettonian model (Ostwald-deWaele)were verified with experimental results. The Ostwald-deWaele model shows the good agreement to the real flow and filling phenomena in die cavity. To give a boost the economical efficiency of Thixoforming process and to ensure the good forming result, reheating device coupled die set was proposed and the initial billet temperature for system that was found from experimental resluts. This study presents an overview of application of numerical analysis for simulation of semi-solid metal forming process to reduce the lead time for development of manufacturing part in industrial field.

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A Study on Conrol of Surfacial and Internal Microsructure in Thixoforming Process (반용융 성형공장에서 표면 및 내부 조직 제어에 관한 연구)

  • 이동건
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.03b
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    • pp.169-172
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    • 1999
  • Thixoforming process has been accepted as a new method for fabricating near net shaped products with lighweight aluminum alloys. The thixoforming process consists of reheating process of billet, billet handing filling into the die cavity and solidification of thixoformed part,. in this paper the thixoforming experiments are performed with two different die temperature ({{{{ TAU _d}}}}=20$0^{\circ}C$ 30$0^{\circ}C$) and orifice gate type. The microstructures of SSM(357, A490 and ALTHIX 86S) fabricated in thixoforming process are evaluated in therms of globularization and grain size. effect of alloying elements onthe surface and internal defects is investigated. Finally the methods to obtain the thixoformed products with good mechanical propertis are proposed by solution for avoiding the surface and internal defects.

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Forming of Compressor Piston Part of Metal Matrix Composites by Thixoforming Process (Thixoforming을 응용한 금속복합재료의 콤푸레서용 피스톤 제품의 성형)

  • 이동건;강충길
    • Transactions of Materials Processing
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    • v.10 no.3
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    • pp.223-234
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    • 2001
  • The characteristics of thixoforming process can decrease liquid segregation because of the improvement in fluidity in a globular microstructure state and utilizes flow without an air entrapment. Therefore, in order to obtain the sound parts of metal matrix composites by using thixoforming process which has co-existing solidus-liquidus phase, it is very important to design a die shape property and to obtain the fabrication conditions which affect the unifomity of the solid fraction on unfilling state and various defects throughout the fabricated parts. The die designs and fabrication conditions to obtain the good piston part are proposed for thixoforging process of metal matrix composites. When reheated metal matrix composites billets were transferred to the closed die gate, thixoforging were carried out under the various pressure(60, 80, 100MPa) with controled forging speed. The mechanical properties such as hardness and tensile strength for thixoforged parts have been investigated after T6 heat treatment.

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Process Control and Thixoforming of Cu Rotor for High Efficiency Motors (고효율 전동기용 Cu Rotor의 반응고 성형과 공정변수 제어)

  • Jung, W. S.;Lee, S. Y.;Shin, P. W.
    • Transactions of Materials Processing
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    • v.14 no.7 s.79
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    • pp.642-648
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    • 2005
  • Rotor in small-medium induction motor has been usually manufactured by aluminum diecasting. In order to improve the efficiency of induction motors, newly developed Cu-Ca alloys have been investigated. The electrical conductivity in the Cu alloys containing Ca less than $1.0wt\%$ was higher than $80\%$ IACS. Cu-Ca alloy is desirable for the thixoforming process because it has wide semi-solid range over $150^{\circ}C$. In this study, Cu-rotor with thixoforming process was developed to replace the conventional aluminum diecasting rotor. Analysis was performed for the microstructure of thixoforming rotor. Effect of incomplete filling on the efficiency of induction motor was discussed.

Fabrication of a Joint Node for an Aluminum Frame for a Low Speed Electric Vehicle using Thixoforming Technology (저속 전기자동차용 알루미늄 차체 조인트 노드의 반응고 성형)

  • Lee, S.Y.
    • Transactions of Materials Processing
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    • v.23 no.4
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    • pp.244-249
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    • 2014
  • The thixoforming process has been applied to forming of a joint node for the aluminum frame of a low speed electric vehicle. A joint node should connect three aluminum extruded chassis showing different profiles. The MHS(magnetohydrodynamic stirring) A357 billet was selected because homogeneous globular grains are necessary as the billet materials for thixoforming. A careful design of joint node has been performed by the considerations of structural demands and the simulation results for the thixoforming process using the MAGMAsoft. Optimum heating temperature for the A357 billet was between 580 and $585^{\circ}C$ corresponding to the semi-solid temperatures showing 20-30% of liquid fraction. An injection speed of around 100mm/s and preheating of die at temperatures of $200^{\circ}C$ were also necessary conditions to obtain reasonable thixoformed parts.

The effect of the size of the Si on mechanical properties of large suspension part in thixoforming process (Thixoforming 공정에서 Si의 크기가 대형 suspension 부품의 기계적 성질에 미치는 영향)

  • 신현기;서판기;박계주;강충길
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.808-811
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    • 2002
  • In thixoforming process, the size of Si particles is changed by many parameters of forming. Especially, reheating and heat treatment are very important parameters. It was found that the mechanical properties was significantly improved by the thixoforming process. In this study, to investigate the relation between the mechanical properties and Si particles, the experiment of semi-solid die casting has been performed. Large suspension part with A356 alloy was fabricated with controlled ram speed. The effect of the size and shape of silicon particles on microstructure of tensile test has been investigated.

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Process Control and Thixoforming Cu Rotor for High Efficiency Motors (고효율 전동기용 Cu Rotor의 반응고 성형과 공정변수 제어)

  • Jung W. S.;Lee S. Y.;Shin P. W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.233-236
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    • 2005
  • Rotor in small-medium induction motor has been usually manufactured by aluminum diecasting. In order to improve efficiency of induction motors, newly developed Cu-Ca alloys have been investigated. The electrical conductivity in the Cu alloys containing Ca less than $1.0wt\%$ was higher than $80\%$ IACS. Cu-Ca alloy is desirable for the thixoforming process because it has wide semi-solid range over $150^{\circ}C$. In this study, Cu-rotor with thixoforming process was developed to replace the conventional aluminum diecasting rotor. Analysis microstructure of thixoforming rotor. effect of incomplete filling defect on the efficiency of induction motor was discussed.

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A Study about Relationship between the Mechanical Properties and Globule Size in Thixoforming Process of Aluminum Alloys (알루미늄재료의 Thixoforming공정에서 구상의 크기가 기계적 성질에 미치는 영향)

  • Park S. M.;Shin H. G.;Kang C. G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2001.10a
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    • pp.236-239
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    • 2001
  • In thixoforming, the globule size is determined by the hoding time of last reheating stage. In this study, some experiments to investigate the relationship between the mechanical properties and the holding time were performed A357, A390 and A3l9 alloys are used in this study. This paper shows the evolution of the microstructure according to the holding time of last reheating stage. Tensile test was performed for each reheating condition to examine the effect of globule size.

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