• Title/Summary/Keyword: Drawing strain

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A Study on Reduction Distribution in Tube Drawing Process (튜브 인발공정시 압하량 배분에 관한 연구)

  • Lee D. H.;Kim D. W.;Kim D. H.;Moon Y. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2004.05a
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    • pp.35-38
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    • 2004
  • In general, tube drawing process is composed of two steps, so called first drawing and second drawing. Drawing cracks are mainly occurred during the 2nd drawing process due to the improper drawing process. In order to analyze the reduction distribution in successive two-step drawing process, tube drawing process was simulated by finite element method. From the finite element analysis, the balance between first and second reduction is proved to be important factor to prevent drawing cracks. Hence the numerical expression was developed for tube drawing process to distribute even strain and criteria curves that can predict the safe drawing region were also proposed using this numerical formula.

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Strain Evolution in High-Mn Steel Ellipsoidal Vessel Head during Multi-forming Process: A Finite Element Analysis (다단 성형 공정 시 고-Mn 강의 타원형 용기 헤드에서의 변형률 분포: 유한요소해석)

  • Preetham Alluri;Lalit Kaushik;Shi-Hoon Choi
    • Transactions of Materials Processing
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    • v.32 no.5
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    • pp.268-275
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    • 2023
  • ISO 21029 cryogenic vessel is used to transport cryogenic fluids. High-manganese steel (High-Mn steel) is widely regarded as suitable for use at cryogenic temperatures. The conventional way of manufacturing an ellipsoidal vessel head involves incremental stretching, followed by a spinning process. In this study, an alternative method for forming an ellipsoidal vessel head was proposed. Finite element analysis (FEA) was used to theoretically examine the strain evolution during a multi-stage forming process, which involved progressive stretching, deep drawing, and spinning of High-Mn steel. The distribution of effective strain and strain components were analyzed at different regions of the formed part. The FEA results revealed that only normal strains were evident in the dished region of the vessel head due to the stretching process. However, the flange region experienced complex strain evolution during the subsequent deep drawing and spinning process.

Simulation of Texture Evolution and Anisotropic Properties in DP Steels during Deep Drawing Process (디프도로잉 시 DP강의 집합조직 및 이방성 거동 모사)

  • Song, Y.S.;Kim, B.J.;Han, S.H.;Chin, K.G.;Choi, S.H.
    • Transactions of Materials Processing
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    • v.17 no.7
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    • pp.517-522
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    • 2008
  • A visco-plastic self-consistent (VPSC) polycrystal model has been applied to simulate texture simulation and anisotropic properties of DP steels during deep drawing process. In order to evaluate the strain path during deep drawing, a steady state was assumed in the flange part of deep drawn cup. The final stable orientations were strongly dependent on the initial location in the blank. The evolution of anisotropy of DP steel sheets has been demonstrated through comparison of plastic strain rate vector at the different plastic strain levels.

Press Formabilities of Aluminum Sheets for Autobody Application (차체용 알루미늄 판재의 프레스 성형성)

  • Kim, Y.S.;Kim, K.S.;Kwon, N.C.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.1
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    • pp.73-83
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    • 1994
  • Press formabilities of aluminum sheets for automobile body were investigated. Plane strain stretching test (called RIST-PSST), cupping test and U bending test were performed to assess the press formability of aluminum sheets respectively. The results showed that aluminum sheets are generally inferior to cold-rolled steel sheet of deep drawing quality (CSP3N) in press formability. The limiting punch height (LPH) and limiting plane strain (FLCo) of aluminum sheets are 50%-70% level compared to that of CSP3N. Moreover, the limiting drawing ratios(LDR) of aluminum sheets are ranged between 1.95 and 2.1. The poor press formability of aluminum sheets is responsible for low values of total elongation and plastic anisotropy parameter in tensile characteristic. The shape fixability of aluminum sheets evaluated in U bending test is very poor due to its low elastic modulus compared to CSP3N.

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Finite Element Analysis and Experimental Verification for the Drawing Characteristics Through Drawbeads (드로오비드 인출특성에 관한 유한요소해석 및 실험적 검증)

  • 김창만;임영석;서대교
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.8
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    • pp.1844-1853
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    • 1995
  • Theoretical and experimental drawing characteristics for the single circular and square drawbeads are discussed. During the blank holding process, the strain distributions of upper and lower skins of specimens, and the die reactional forces are analysed by F. E. M., and they are compared with the experimental results. The drawbead restraining forces and strain distributions for the drawn specimens by the various drawing length are also analysed and compared with the experimental results. It is concluded that the theoretical simulations and results could be very useful for the prediction of real cases.

Simulation of Texture Evolution and Anisotropic Properties in DP steels during Deep Drawing Process (디프드로임 시 DP강의 집합조직 및 이방성 거동 모사)

  • Song, Y.S.;Kim, B.J.;Han, S.H.;Chin, K.G.;Choi, S.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.396-399
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    • 2008
  • A visco-plastic self-consistent (VPSC) polycrystal model has been applied to simulate texture simulation and anisotropic properties of DP steels during deep drawing process. In order to evaluate the strain path during deep drawing, a steady state was assumed in the flange part of deep drawn cup. The final stable orientations were strongly dependent on the initial location in the blank. The evolution of anisotropy of DP steel sheets has been demonstrated through comparison of plastic strain rate vector at the different plastic strain levels.

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Drawing Strain Distribution Model for the Two-Pass Drawing Process (2단 튜브인발 공정시 인발변형률 배분모델 재발)

  • Lee D. H;Chung U. C;Moon Y. H
    • Transactions of Materials Processing
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    • v.13 no.8
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    • pp.671-677
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    • 2004
  • For the large reduction in tube cross section, the tube drawing process is usually performed by two successive passes, so called first drawing and second drawing. In multi-pass drawing process, the reduction balance is important to prevent drawing cracks. Therefore in this study, the model for uniform reduction distribution in two-pass drawing process has been developed on the basis of cross sectional variation of drawn tube. For the given product geometry the model provides optimal diameter and thickness that can evenly distribute drawing reductions. The capability of model is well confirmed by finite element analysis of tube drawing process. Criteria curves at various limit strains to determine whether the drawn tube would fail during drawing process are also proposed by using newly developed model.

Evaluation of Radial Direction Non-uniform Strain in Drawn Bar (인발 봉재의 반경방향 불균일 변형률 평가)

  • Lee, S.M.;Lee, I.K.;Lee, S.Y.;Jeong, M.S.;Moon, Y.H.;Lee, S.K.
    • Transactions of Materials Processing
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    • v.29 no.6
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    • pp.356-361
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    • 2020
  • In general, the drawing process is performed in a multi-pass to meet the required shape and cross section. In the drawn material, the surface strain is relatively higher than the center due to the direct contact with the die. Therefore, a non-uniform strain distribution appears in the surface of the material where the strain is concentrated and the center having a relatively low strain, thus it is difficult to predict the strain in the drawn material. In this study, the non-uniform strain distribution was evaluated using a finite element analysis and the non-uniform strain distribution model based on the upper bound method. In addition, the relationship between the hardness and the strain was established through a simple compression test to evaluate the distribution of the strain in the experimentally multi-pass drawn bar.

A Study on the Prediction of Limit Drawing Ratio And Forming Load in Redrawing of Sheet Metal (박판의 재인발 가공 에서의 한계인발비 및 성형하중 의 예측 에 관한 연구)

  • 박장호;양동열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.7 no.3
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    • pp.249-256
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    • 1983
  • The study is concerned with the analysis of sheet metal for the prediction of limit drawing ratio and forming load. The direct redrawing process is analyzed by using an equilibrium approach and strain increment theory both for non-workhardening material and for workhardening material. Computations are carried out numerically for the workhardening case. Limit drawing ratios are predicted for some chosen variables. The forming loads are also computed with respect to punch travel. Then the predicted loads are compared with the experimental results. For ordinary lubricated conditions, the comparison shows reasonable agreement between the theory and experimental observation. It is also shown that limit drawing ration can be increased by using a greater die angle and proper lubrication significantly reduces the punch load. Finally numerical results show that material of greater R-value and strain-hardening exponent(n)is better for direst redrawing of sheet metal.

Prediction of Earings in the Deep Drawing Processes of a Cylindrical Cup (원통컵 디프드로잉 공정의 귀발생 예측)

  • 이승열;이승열;금영탁;정관수;박진무
    • Transactions of Materials Processing
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    • v.4 no.3
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    • pp.222-232
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    • 1995
  • The planar anisotripic FEM analysis for predicting earing profiles and draw-in amounts in the deep-drawing process is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-based unit vector and normal contact pressure. The consistent full set of governing relations, which is comprising euilbrium and geometric constraint equations, is appropriately linearized. Barlat's strain-rate potential is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and potential parameters. The linear triangular membrane elements are used for depicting the formed sheet. In the numerical simulations of deep drawing processes of a flat-top cylindrical cup for 2090-T3 aluminum alloy sheet show good agreement with experiments, although some discrepancies were observed in the directional trend of cup height and thickness strains.

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