• Title/Summary/Keyword: Warm hydroforming

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Development of Manufacturing Technology for Aluminum Automotive part with Warm Hydroforming (온간하이드로포밍을 이용한 알루미늄 자동차부품 제조기술 개발)

  • Sohn, S.M.;Lee, M.Y.;Kim, B.J.;Moon, Y.H.;Lee, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.06a
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    • pp.93-98
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    • 2006
  • Warm forming technology was classified into hot gas forming of using compressible fluid as a nitrogen gas and warm hydroforming of using the incompressible fluid as a thermal oil by using medium fluid. In this study, the aluminum side-rail part was developed with warm hydroforming technology. For the warm hydroforming system, top and bottom die was designed to insert heating cartridge in die cavity and special indirect fluid heating system was designed to heat the thermal oil. As increase the temperature, hydroformability was increased linearly. Aluminum side-rail center part was formed 90% at the internal pressure of 100bar and perfectly formed at 300bar within a moderate temperature. The tube material used for warm hydroforming was a aluminum 6000 series alloy with the diameter of 120mm, thickness of 5mm, length of 1,300mm. Warm hydroformed side-rail center part had 20% of maximum expansion ratio and below 20% of maximum thinning ratio at corner radius. This results were provided to show warm hydroforming possibility for aluminum automotive components.

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Warm Hydroforming Characteristics of High Strength Aluminum Tubes (고강도 알루미늄 튜브의 온간 하이드로포밍 특성)

  • 이문용;강창룡;이상용
    • Transactions of Materials Processing
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    • v.13 no.5
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    • pp.403-408
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    • 2004
  • Hydroformability of 6061 and 7075 aluminum tube materials was studied by warm hydroforming experiments. A special tooling and heating system was designed and manufactured in order to perform warm hydroforming between room temperature and $300^{\circ}C$. The control of tube temperature for warm hydroforming was made by the control of temperature of oil medium. Warm hydroformability was analyzed by tube appearances, tube elongation and hardness values. Hydroforming characteristics of 6061 and 7075 tubes showed different temperature dependence between room temperature and $300^{\circ}C$. The difference in hydroformabilities of 6061 and 7075 at elevated temperatures was interpreted by the different sensitivity to dynamic strain aging of both aluminum materials.

A study on the formability with heat treatment and deformation temperature in warm hydroforming of Al 6061 tube (Al6061 tube의 열처리조건과 온도에 따른 액압성형성에 관한 특성 연구)

  • Yi H. K.;Lee Y. S.;Moon Y. H.;Lee J. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.255-258
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    • 2005
  • In this study, the effect of heat treatment conditions and deformation temperature on the formability were investigated in warm hydroforming of Al 6061 tube. Full annealing and T6-treatment for heattreatment of Al6061 tube were used in this study. To evaluate the hydroformability, uniaxial tensile test and bulge test were performed between room temperature and $300^{\circ}C$. And measured flow stress was used to simulate the hydroforming of Al 6061. A commercial FEM code, DEFORM2D, was used to calculate the damage and strain variation. The calculated values were efficient to predict the forming limit in hydroforming for real complex shaped part.

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A study on the formability in warm hydroforming of Al 6061 seamless tube (온간액압성형공정에서 Al 6061 튜브의 소성변형특성에 관한 연구)

  • Yi, H.K.;Lee, Y.K.;Lee, J.H.;Sohn, S.M.;Moon, Y.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.05a
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    • pp.318-321
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    • 2006
  • In this strudy, the free-bulge test and FE analysis have been used to define the fracture criteria based on the cockroft and Latham's criterion in warm hydroforming of Al 6061 tube. Full annealing and T6 treatment for heat treatment of Al 6061 tube ware used in this study. As-extruded, full annealed and T6-treated Al 6061 seamless tubes were prepared. To evaluate the hydroformability, uni-axial tensile test and bulge test were performed between room temperature and $200^{\circ}C$. And measured flow stress was used to simulate the warm hydroforming. A commercial FEM code, DEFORM-$2D^{TM}$, was used to calculate the damage value. A forming limit based ductile fracture criteria has been proposed by the results of experimental and FE analysis. The calculated values for fracture criteria will be efficient to predict the forming limit in hydroforming for real complex shaped part.

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Finite Element Analysis and Experimental Confirmation of Warm Hydroforming Process (온간 하이드로포밍에 관한 유한요소해석 및 실험적 검증)

  • Kim, B.J.;Park, K.S.;Choi, K.H.;Moon, Y.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.05a
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    • pp.277-280
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    • 2006
  • The hydroformability of aluminum alloy sheets at elevated temperatures have been investigated in this study. It is necessary to analyze the variations of the mechanical properties that depend on the forming temperature and the heat conduction during warm hydroforming. Therefore, in this study a coupled simulation of plastic deformation and temperature distribution in the warm hydroforming process is performed and compared with experimental data. The multi-purpose code DEFORM-2D can handle this type of calculations but it takes high computation time if contact heat transfer between die, tube and pressure medium occurs. Experiments were conducted by high temperature tribometer(pin-on-disk) allowing measuring the friction coefficients of the aluminum alloys at several temperatures and these results are applied to the coupled simulation by which the optimal process parameters such as internal pressure and preset temperature on hydroformability can be determined. The comparison of the FE analysis with the experimental results has shown that hydroformability given by bulge height, and temperature distribution of the tube specimen make a little difference with the FE results but the trend predicted by simulation agrees well with experiments.

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Process Design for the Tubular Hydroforming at Elevated Temperatures (온간 하이드로포밍 공정을 위한 시스템 설계)

  • Kim, B.J.;Park, K.S.;Sohn, S.M.;Lee, M.Y.;Moon, Y.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.05a
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    • pp.226-229
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    • 2006
  • Process design has been performed for the warm hydroforming of light weight alloy tubes. For the heating of tubes, specially designed induction heating system has been adopted to ensure rapid heating of tubes. The induction heating system uses 30kHz frequency induction coil in order to concentrate the energy in the tube and prevent the energy loss. But the induced heat by the integrated heating system, consisting of induction coil, tube, pressure oil and dies, was normally not equally distributed over the length and circumference of the tube specimen, and consequent temperature distribution was non-uniform. So additional heating element has been inserted into the inside of the tube to maintain the forming temperature and reduce temperature drop due to heat loss to the molds. And for that heat loss, a heat insulation system has also been installed. The drop in flow stress at elevated temperatures results in lower internal pressure for hydroforming and lower clamping forces. The proposed warm hydroforming process has been successfully implemented when applying 6061 aluminum extruded tubes.

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Prediction for Forming Limit of Tube Warm Hydroforming Based on the Ductile Fracture Criteria (연성파괴 이론을 적용한 튜브 온간액압성형의 성형한계 예측)

  • Yi, H.K.;Moon, Y.H.;Lee, J.H.;Lee, Y.S.
    • Transactions of Materials Processing
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    • v.16 no.6
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    • pp.426-431
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    • 2007
  • Hydroformability and fracture criteria of FE analysis based on ductile fracture were investigated in warm hydroforming of A16061 tube. To evaluate the hydroformability, uni-axial tensile test and bulge test were performed at room temperature and $200^{\circ}C$. The measured flow stresses were used as input parameters for FE analysis. The damage values were calculated by FE analysis based on ductile fracture criteria at maximum radius of free bulged tubes. Damage values were compared of hexagonal shaped hydroformed parts. As a result, the formability by critical damage value for extruded tube is lower than that of full annealed tube up to 0.5.

A study on the deformation characteristic of heat-treated 6061,7075 aluminum alloy with changes of elevated temperature and strain rate for warm hydroforming (열처리된 알루미늄 6061, 7075 합금의 온간 액압 성형 적용을 위한 온도 및 변형 속도 변화에 따른 변형 특성 연구)

  • Yi H. K.;Moon Y. H.;Sohn S. M.;Lee M. Y.;Suh D. W.;Lee S. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2004.10a
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    • pp.23-26
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    • 2004
  • The deformation behaviors of fully annealed or T6-treated 6061 and 7075 aluminum tubes are investigated at elevated temperature using uniaxial tensile test. Fully annealed 6061 and 7075 tube, and T6-treated 7075 tube do not show sharp local necking with an elongation of $50\%$ at tensile temperature of $300^{\circ}C$, accordingly, it is expected that warm hydroforming process can be applied. The increase of tensile temperature does not significantly affect the total elongation of T6-treated 6061 tube.

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Studies on the Warm Hydroformability of Aluminum Tubes (알루미늄 튜브 온간 하이드로포밍 성형성에 관한 연구)

  • Kim B. J.;Ryu J. S.;Kim D. H.;Kim D. W.;Moon Y. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2004.05a
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    • pp.198-201
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    • 2004
  • Aluminum alloys have high potential for weight reduction in automotive and other applications. But aluminum alloys have relatively low tubular hydroformability which can be enhanced by conducting the hydroforming at elevated temperatures. Hot working processes are commonly used in bulk forming such as forging and rolling, but still is rare in sheet metal forming like hydroforming. In this study hydroforming test at elevated temperatures is performed by special designed induction heating system to investigate the hydroformability of aluminum alloys. The high temperature formability characteristrics are obtained by 1?fitting forming test and circular bulging test and the effects of the process parameters such as feeding amount, internal pressure and temperatures on the tubular forming limits are mainly investigated.

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The Effect of the Heating Conditions on the Warm Hydro-Formability of the Alumium Alloys (알루미늄합금의 열간 액압성형법 성형성에 대한 가열조건의 영향도 분석)

  • Kim, Bong-Joon;Park, Kwang-Su;Ryu, Jong-Soo;Son, Sung-Man;Moon, Young-Hoon
    • Journal of the Korean Society for Heat Treatment
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    • v.18 no.3
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    • pp.172-176
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    • 2005
  • Modern automobiles are built with a steadily increasing variety of materials and semifinished products. The traditional composition of steel sheet and cast iron is being replaced with other materials such as aluminum and magnesium. But low formability of these materials has prevented the application of the automotive components. The formability can be enhanced by conducting the warm hydroforming using induction heating device which can raise the temperature of the specimen very quickly. The specimen applied to the test is A6061, A7075 extruded tubes which belong to the age-hardenable aluminum alloys. But in the case of A6061 age hardening occurs at room temperature or at elevated temperatures before and after the forming process. In this study the effects of the heating condition such as heating time, preset temperature, holding time during die closing and forming time on the hydroformability are analyzed to evaluate the phenomena such as dynamic strain hardening and ageing hardening at high temperatures after the hydroforming process.