• Title/Summary/Keyword: Draw Bead Surface

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Analysis-based Die Face Design for the Improvement of Surface Quality for a Heat Protect Panel of an Automobile (차량용 열차단판의 면품질 개선을 위한 성형해석 기반 금형면 설계)

  • Kim, K.P.;Kim, S.H.;Lee, D.G.;Jang, K.C.
    • Transactions of Materials Processing
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    • v.17 no.4
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    • pp.278-283
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    • 2008
  • This paper concerns the die face design for a heat protect panel aided by the finite element forming analysis in order to eliminate the surface defect and to improve the surface quality. The CAE procedure of the stamping process is introduced in order to reveal the reason of surface inferiorities and to improve surface quality. Complicated shape of the product induces the surface inferiorities such as wrinkling due to the insufficient restraining force of the forming blank and the non-uniform contact of the blank with the tools. This paper proposes a new guideline for the die design which includes the modification of tool shapes and addition of the draw-beads on the tool surface for ensuring the increased the restraining force with the uniform contact condition. The effectiveness of the proposed design is verified by the forming analysis and is confirmed by the tryout operation in the press shop. The analysis and test results show that the modified process parameters such as tool shapes and draw-beads can reduce the tendency of wrinkling and improve surface quality.

Stress-Based Springback Reduction of an AHSS Front Side Member (고강도강 프런트 사이드멤버의 음력분포 최적화를 통한 스프링백 저감)

  • Song, J.H.;Kim, S.H.;Huh, H.;Park, S.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.06a
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    • pp.61-67
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    • 2006
  • Optimization is carried out to determine process parameters which reduce the amount of springback and improve shape accuracy of a deep drawn product in sheet metal forming process. The study uses the amount of stress deviation along the thickness direction in the deep drawn product as an indicator of springback instead of springback simulation. The scheme incorporates with an explicit elasto-plastic finite element method for calculation of the final shape and the stress deviation. The optimization method adopts the response surface method in order to seek for the optimum condition of the draw-bead force. The present scheme is applied to the design of draw-bead force in a front side member formed with advanced high strength steel (AHSS) sheets of DP60. Results show that design of process parameter is well performed to decrease the stress deviation through the thickness and to reduce the amount of springback. The present analysis provides a guideline in a design stage for controlling the springback based on the finite element simulation of the complicated parts.

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An Angle-Binder Drawbead Simulator for Measuring Drawbead Forces on Inclined Binder Surface (경사진 바인더면의 드로우비드력을 측정하기 위한 모의실험장치)

  • Yang, W.H.;Choi, K.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.180-184
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    • 2009
  • A novel set of experimental test tooling for measuring pulling and holding forces for drawbeads on binders inclined at a wide range of angles is introduced. A mechanical design featuring a single load cell, a male-female draw bead set, translation and rotation degrees of freedom, and a screw-driven clamping system has been incorporated into a standard tensile test machine. On a real time basis, restraining and holding force data with respect to draw-in displacement may be directly downloaded into a PC for data processing. The proposed experimental system represents a significant breakthrough in drawbead simulation technology due to its relatively low cost, clever design, and versatility. The system is shown to yield excellent experimental data suitable for verifying theory and numerical model predictions.

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Multi-objective Optimization to Reduce Wrinkle & Thinning in Sheet Metal Forming of Ultra High Strength Steel (1.2GPa) (1.2GPa 강판의 판재성형에서 주름 및 성형성 향상을 위한 다중 목적함수 최적 설계)

  • Lee, Y.S.;Kwon, S.H.;Kim, H.L.;Kim, S.W.;Jung, C.Y.;Hong, S.
    • Transactions of Materials Processing
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    • v.25 no.5
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    • pp.295-300
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    • 2016
  • Recently, Ultra High Strength Steel (UHSS) sheet metal has been widely used to improve lightweight structures in the automobile industry. Because UHSS sheets have high strength but low elongation, it is difficult to control winkle and thinning for complex shaped products. The draw beads on die surface were introduced in this study to reduce wrinkle and thinning. The positions and strength values of draw beads were selected as design variables and optimized using finite element analysis. The beads positions and strength of a mold for B-pillar part were designed with the proposed optimization method. The accuracy of die design from optimization was verified by comparing with the results from 3-D scanned geometry.

Effect of various surface roughness of steel sheet on characteristic of surface friction in stamping (판재의 표면 거칠기에 따른 표면 마찰 특성 변화)

  • 조상헌;허보영;아라이히로시;주상응;김상열;이용진;문만빈;이영수;고흥석
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.24-24
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    • 2003
  • 최근 자동차 산업이 발달함에 따라 철강업계와 자동차 회사에서는 전에 많이 사용하던 내연 무도금강판 대신 부식에 저항력이 강한 도금강판을 사용한 이후로 냉연강판의 가공 시에 야기되지 않았던 많은 문제점들이 나타났다 자동차용 강판의 경우 판재의 체적에 비하여 금형과 판재의 접촉면적이 큰 프레스 공정에서는 판재의 표면에 작용하는 마찰력의 크기가 판재의 스탬핑 성형성에 큰 영향을 미친다. 이는 마찰특성이 비록 재료고유의 성형한계에서는 영향을 미치지 못하나 스탬핑 공정에 있어서 금형과의 접촉면에서 마찰력의 크기가 패널의 변형률분포를 변화시켜 스탬핑 성형성에 큰 영향을 주는 것이다. 따라서 본 연구는 자동차용 도금강판의 표면 거칠기에 따른 판재의 표면 마찰 특성 변화를 알아보았다. 소재의 기계적 특성 측정은 UTM을 사용하였고, 도금층은 XRD, SEM을 이용하여 상분석 하였으며, 표면 거칠기는 AFM(Atomic Force Microscope), SJ-400(Mitutoyo)을 사용하여 표면 거칠기를 측정하였다. 또 드로잉 하중을 비드부에서의 굽힘-굽힘 풀림 소성변형에 의한 변형력 성분과 마찰력 성분으로 분리하여 강판의 쿠롬 마찰계수를 DBS(Draw bead simulation)로 측정하였다.

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Frictional characteristics of electro Zn-Ni alloy coated steel sheets (Zn-Ni계 합금도금강판의 마찰특성에 관한 연구)

  • 김영석;박기철;조재억
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.6
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    • pp.1807-1818
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    • 1991
  • The frictional characteristic of Zn-Ni electrogalvanized steel sheet was investigated by experimental procedures. To clarify the effect of surface property on the frictional characteristic of Zn-Ni coated steel sheet, Micro-hardness test, SEM analysis and X-ray diffraction analysis were carried out. Coefficients of friction for various stamping lubricant and Ni content in coated layer were measured by a draw bead friction test. The results show that frictional characteristic is very sensitive to Ni content of coated layer and depends on stamping lubricant. For Ni content less than about 11%, selection of proper lubricant is necessary to obtain low coefficient of friction in Zn-Ni coated steel sheet such as in case of cold rolled steel sheet.

Tool Design and Numerical Verification for Thick Plate Forming of Hollow-Partitioned Steam Turbine Nozzle Stator (스팀 터빈용 중공 분할형 노즐 정익의 후판 성형을 위한 금형 설계 및 해석적 검증)

  • Kang, B.K.;Kwak, B.S.;Yoon, M.J.;Jeon, J.Y.;Kang, B.S.;Ku, T.W.
    • Transactions of Materials Processing
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    • v.25 no.6
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    • pp.379-389
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    • 2016
  • As a stator for steam turbine diaphragm, hollow-type nozzle stator to substitute for conventional solid one is introduced in this study. This hollowed stator can be separated into two parts such as upper and lower plates with large and curved surface area. This study focuses on thick plate forming process for the upper plate of the hollow-partitioned nozzle stator. First, to reduce forming defects such as under-cut and localized thinning of the deformed plate, and to avoid tool interruption between forming punch and lower die, tool design including the position determination of forming surfaces is performed. Uni-axial tensile tests are carried out using SUS409L steel plate with initial thickness of 5.00mm, and plastic strain ratio (r-value) is also obtained. Due to the asymmetric curved configuration of the upper plate, it is hard to adopt a series of blank holder or draw-bead, so the initial plate during this thick plate forming experiences unstable and non-uniform contact. To easy this forming difficulty and find suitable tool geometry without sliding behavior of the workpiece in the die cavity, two geometric parameters with respect to each shoulder angle of the lower die and the upper punch are adopted. FE models with consideration of 21 combinations for the geometric parameters are built-up, and numerical simulations are performed. From the simulated and predicted results, it is shown that the geometric parameter combinations with ($30^{\circ}$, $90^{\circ}$) and ($45^{\circ}$, $90^{\circ}$) for the shoulder angle of the lower die and the upper punch are suitably applied to this upper plate forming of the hollow-partitioned nozzle stator used for the turbine diaphragm.