• 제목/요약/키워드: Combined Extrusion

검색결과 69건 처리시간 0.024초

COMBINED FORWARD-BACKWARD EXTRUSION WITH REVERSE RAM MOTION -APPLICATION TO FORMING OF GEAR-

  • Otsu M.;Hayashida D.;Osakada K.;Hanami S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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    • pp.158-161
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    • 2003
  • Extrusion of forward-gear and backward-rod by combined extrusion with controlling the extrusion velocity using a counter tool is studied. In the combined forward-backward extrusion with controlling extrusion velocity, only parts with short gear can be formed. To obtain longer gear parts, extrusion with reverse ram motion is carried out after the combined forward-backward extrusion process. In this method, combined forward-backward extrusion is carried out until excessive extrusion length is attained and then, the motion of the punch is stopped and the counter tool is moved in the inverse direction and returned to the position for obtaining the desired extrusion length. The experiment is carried out by using lead for billets as a model material. With reverse ram motion, longer gear teeth without under-filling defect can be formed than that by only combined extrusion with controlling extrusion velocity.

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A Study on the Forming Characteristics of Radial Extrusions Combined with Forward Extrusion (전방압출과 연계된 레이디얼압출의 성형특성에 관한 연구)

  • 장용석;황병복
    • Transactions of Materials Processing
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    • 제9권3호
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    • pp.242-248
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    • 2000
  • This paper is concerned with the family of parts that generally feature a central hub with radial protrusions. Radial Extrusion is usually used in order to produce complex parts, which is combined with upsetting and/or forward and backward extrusion. Typical parts that fall into this category include cross pieces for universal joints, key-shaft type parts, tube fittings, and differential gears. In this paper, the forming characteristics of radial extrusion combined with forward extrusion is investigated by comparing the punch and mandrel loads. The design factors during radial extrusion combined with forward extrusion are applied to the simulation to see how much those factors have effect on the forming loads. The rigid-plastic FEM is applied to the simulation.

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COMBINED FORWARD-BACKWARD EXTRUSION WITH CONTROLLED REVERSAL RAM MOTION -Effect of Reversal Ram Motion-

  • Hanami S.;Matsumoto R.;Otsu M.;Osakada K.;Hayashida D.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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    • pp.162-166
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    • 2003
  • In combined forward-backward extrusion with controlled forward speed by a counter punch, accurate parts with forward rod can be formed. As an extension of this method, reverse extrusion is proposed, in which the extruded forward rod is pushed back while the main punch is kept at the final position after the forward-backward extrusion process. The experiment is carried out using lead as a model material. With the reverse extrusion method, longer forward rods can be formed without under-filling defect than that by combined extrusion with controlling extrusion speed.

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Forming Characteristics of the Forward and Backward Tube Extrusion Using Pipe (중공축 소재를 이용한 전후방 복합압출의 성형 특성)

  • Kim S. H.;Lee H. Y.
    • Transactions of Materials Processing
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    • 제14권9호통권81호
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    • pp.772-778
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    • 2005
  • This paper is concerned with the analysis of material flow characteristics of combined tube extrusion using pipe. The analysis in this paper concentrated on the evaluation of the design parameters for deformation patterns of tube forming, load characteristics, extruded length, and die pressure. The design factors such as punch nose radius, die corner radius, friction factor, and punch face angle are involved in the simulation. The combined tube extrusion is analyzed by using a commercial finite element code. This simulation makes use of pipe material and punch geometry on the basis of punch geometry recommended by International Cold Forging Group. Deformation patterns and its characteristics in combined forward and backward tube extrusion process were analyzed for forming loads with primary parameters, which are various punch nose radius relative to backward tube thickness. The results from the simulation show the flow modes of pipe workpiece and the die pressure at the contact surface between pipe workpiece and punch. The specific backward tube thickness and punch nose radius have an effect on extruded length in combined extrusion. The combined one step forward and backward extrusion is compared with the two step extrusion fer forming load and die pressure.

Forming Characteristics of Magnesium Alloy in Cup-Rod Combined Extrusion Process (AZ31B 마그네슘 합금의 Cup-Rod 복합압출 성형특성 연구)

  • Yoon, D.J.;Kim, E.Z.;Cho, C.D.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 한국소성가공학회 2007년도 추계학술대회 논문집
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    • pp.70-73
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    • 2007
  • The forming characteristics of cup-rod combined extrusion process were investigated with process parameter change. Simultaneous forward rod extrusion and backward cup extrusion was conducted with magnesium alloy, AZ31B. Process parameters such as forward extrusion ratio, backward extrusion ratio, and working temperature were controlled in a specific region and the effects of the parameter change were examined. Surface crack was developed in a certain state of the process parameters combination. The crack-free forming limit of the alloy in the combined process was disclosed by the parameter study. The microstructures of the initial and extruded workpieces were observed.

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A Study of the Plastic Deformation in Axisymmetric Combined Extrusion (축대칭 복합압출공정의 소성변형 연구)

  • 한철호
    • Transactions of the Korean Society of Mechanical Engineers
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    • 제18권8호
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    • pp.2005-2015
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    • 1994
  • An analytical method based on the upper bound approach for the cup-bar axisymmetric combined extrusion is presented to determine the deformation zones as well as extrusion load and deformed geometry in the early stage. A new kiematically admissible velocity field is derived by the appropriate transformation of the original velocity field and applying the flow function approach. The derived velocity field is directly related to the boundary function for the plastically deforming zones and the parameter controlling the flow direction to the forward part or backward part. Experiments are carred out with the annealed aluminum 2024 at room temperature for the various area reductions. The workhardening effect is considered in the formulation as a function of the height ratio between the deformed billet and the orighinal billet to calculate the extrusion pressures. The theoretical predictions for the extrusion loads and deformed configuration are in good agreement with the experimental results.

A Study on Process Improvement of Combined Extrusion with Aluminum Alloy 7075 (유한요소 시뮬레이션을 이용한 알루미늄 7075 복합 압출재에 대한 공정개선 연구)

  • 김진복;이지억;강범수
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 한국추진공학회 1996년도 제6회 학술강연회논문집
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    • pp.197-205
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    • 1996
  • A combined extrusion process studied here consists of forward and backward extrusion, and it is formed in single operation. The metal flow involved in the operation has appeared to be difficult to analyze accurately because of mixed directions of the flow. In this study, conventional two operations of a forward and a backward extrusions is transformed into one operation of mixed extrusion. A process designed by an industry expert is simulated by the rigid-plastic finite element method to investigate the metal flow and defects. In addition to the FEM simulation, experimental analysis has been carried out to confirm the design in industry, which includes material characterization, preliminary expriment, and whole experimental forming operation. The experimental results show that warm forming of extrusion is more desirable than cold working and hot forming in view of grain growth. Also two conditions of lubrication between workpiece and die has been investigated.

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Analysis and Design of a Forming Porcess for Combined Extrusion with Aluminum AIIoy 7075 (알루미늄 7075 복합압출재에 대한 공정해석 및 설계)

  • 김진복;변상규
    • Transactions of Materials Processing
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    • 제6권5호
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    • pp.446-455
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    • 1997
  • A Combined extrusion operation consists of forward and backward extrusion forming and it is possible to make the process be simple by employing it. But the metal flow pattern induced by the operation is hard to analyze accurately because the flows are non-steady, which have at least two directions dependent upon each other. So engineers in the industrial factories had conducted the two extrusion operations separately. A new process was designed by the industrial expert for forming of an alu-minum preform using the combined extrusion operation. In this study, experiments and finite element analysis was carried out to determine the process parameters. Through the preliminary experiment, it was shown that warm forming condition was more desirable than cold or hot ones. And optimal shape of initial billet could be also determined. From the compatibility test, bonde-lube was chosen as the optimal lubricant and 20$0^{\circ}C$ as the material temperature by the inspection of micro-structure. The operation was simulated by the rigid-plastic finite element method to examine the metal flow. Disap-pearing of dead metal zone was observed as the punch fell down and desirable shape was obtained from the one operation. As a result of this study, 7 operations could be reduced and 225% of material saved.

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Finite Element Analysis and Experiment of Combined Extrusion in Semi-Solid State (반용융 복합압출 제품의 성형실험 및 유한요소해석)

  • 최재찬;박준홍;김병민
    • Transactions of Materials Processing
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    • 제8권3호
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    • pp.313-318
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    • 1999
  • Many products related to automobile and airplane industry have been manufactured by semi-solid forging. In this paper finite element analysis of product by combined extrusion in semi-solid state was performed and its experimental verification using A356 was conducted. distribution of solid fraction was analyzed and compared with the experimental microstructure in the product. In addition, distribution of temperature in the product was analysed by finite element method.

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An Influence of the Frictional Condition on Material Flow in Forward/Backward Combined Extrusion Process (전/후방 복합 압출공정에서 마찰조건이 재료 유동에 미치는 영향)

  • Kim, M.T.;Noh, J.H.;Hwang, B.B.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 한국소성가공학회 2009년도 추계학술대회 논문집
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    • pp.433-436
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    • 2009
  • This study is concerned with an effect of frictional condition in a forward/backward combined extrusion process. Generally, the material flow of the billet is influenced by the corners of the die cavity, the ratio in reduction in area, and thickness ratio of backward can thickness to forward can thickness. In addition, the frictional condition in contact area between the billet and the punch/die also affect the material flow. This paper investigated the effect of frictional condition for variable friction factors. The FEM simulation has been carried out in order to examine the effect of frictional condition. Deformation patterns and flow characteristics were examined in terms of design parameters such as extruded length ratio etc. Die pressure exerted on the die-workpiece interface is calculated by the simulation results and analyzed for safe tooling. Therefore the numerical simulation works provide a combined extrusion process of stable cold forging process planning to avoid the severe damage on the tool.

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