• Title/Summary/Keyword: Side-Wall Curl

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Effects of sheet and stamping process variables on side wall curl (딥 드로잉 벽면 만곡에 미치는 소재 및 가공조건의 영향)

  • 박기철;한수식;조태현;황상무
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.03a
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    • pp.53-57
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    • 1998
  • In order to investigate the effects of the variables during the stamping process upon the side wall curl behavior, experiments and finite element analyses were done using a 90 degree draw-bending test. The variables considered were the die radius, the forming speed, the restraint force, the lubrication and the sheet grade. The experiments and simulation conditions were selected according to the design of experiment (DOE) approach. The effects of the restraint force, the lubrication and the forming speed were the same for both high strength and mild steels, but the effects of the die radius on the side wall curl were dependent on the magnitude of the die radius and the sheet grade. A straight side wall was observed for both high strength and mild steels when the die radius was about 2∼3 times of the sheet thickness. It was recommended that the restraint force, the forming speed and the friction be increased in order to reduce the side wall curl.

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A Simplified Approach for Predicting Springback in U-Draw Bending of Sheet Metals (U 드로오 벤딩에서의 스프링백 예측을 위한 이론적 단순화)

  • 장성호;허영무;서대교
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.125-131
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    • 2003
  • The U-draw bending operation is known as a representative test method for springback evaluation of sheet metals since the sheet in U-draw bending operation undergoes stretching, bending and unbending deformations occurred at read stamping process. In this study, a simplified approach was proposed for predicting springback and side-wall curls in U-draw bending operations, using moment-curvature relationships derived for sheets undergoing stretching, bending and unbending deformation.

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A Simplified Approach for Predicting Springback in U-Draw Bending of Sheet Metals (용접 판재의 U 드로오 벤딩에서 스프링백 예측을 위한 이론적 단순화)

  • Chang S. H;Seo D. G.
    • Transactions of Materials Processing
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    • v.13 no.8
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    • pp.678-688
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    • 2004
  • The U-draw bending operation is known as a representative test method for springback evaluation of sheet metals since the sheet in U-draw bending operation undergoes stretching, bending and unbending deformations occurred at the stamping process. In this study, a simplified approach was proposed for predicting springback and side-wall curls of tailor-welded blank in U-draw bending operations, using moment-curvature relationships derived for sheets undergoing stretching, bending and unbending deformation. Two different welded strips were adopted to compare the effects of weld-line locations on the springback. One (type A) was welded along the centerline of the strip-width and the other (type B) was welded along the centerline of the strip-length. To investigate the effect of different thickness combination on the springback, the tailor-welded strips were joined by the laser welding process and consisted of three types of thickness combinations of sheets, SCP1 0.8t * SCP1 1.2t, SCP1 0.8t * SCP1 1.6t and SCP1 0.8t * TRIP 1.0t. Some calculated results by the simplified formula were compared with experimental results.

Robust design of springback in U-channel forming using complex method (콤플렉스법을 이용한 U-채널 성형의 스프링백 강건 설계)

  • Yin, Jeong-Je;Kim, Kyung-Mo;Park, Jong-Cheon
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.12 no.1
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    • pp.117-125
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    • 2013
  • Variations of springback in stamped parts are induced by the uncontrollable noises including the variation of incoming material properties, lubrication and other forming process parameters. Reduction of springback variation is very important during springback compensation processes on stamping dies and assembly processes. To reduce the variation of springback, a robust optimization methodology which uses complex method combined with orthogonal array is proposed. The proposed method is applied to the robust design of U-channel die for the reduction of side wall curl. It is shown that the drawbead and die radius of U-channel draw die can be effectively optimized by the proposed method.

A Forming and Springback Analysis for the U-channel Draw (U-channel Draw 성형 및 스프링백 해석)

  • Choi, E.K.;Park, K.S.;Oh, H.K.;Yu, D.H.;Lee, S.W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.465-468
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    • 2008
  • In this paper, ABAQUS, one of the implicit finite element codes, is used to analyze the U-channel Draw benchmark problem of NUMISHEET 2005. Forming and springback stages have been done consecutively to compare their results with the experimental ones. The main measures for comparing are the side wall curl and angle. The result by numerical analysis are shown generally to be correspondent with the experimental results that the max. error is confined under about 10%.

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Experimental Simulation of Local External Forcing of the Contained Rotating Flow (회전반 유체실험에서 국지적 외력의 실험적 모의)

  • Yi, Chang-Won;Na, Jung-Yul
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.5 no.2
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    • pp.77-85
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    • 2000
  • Simulation of local external forcing and its response in the rotation table experiment has been investigated. Spatially-uniform external forcings have been applied in many experimental studies, however, based on the fact that the north-south distribution of the wind-stress curl and the existence of local maximum of the sea surface heat loss in the northern part of the East Sea, new method of combined effects of local forcings has been employed in separate experiments. Carefully designed local source or sink at the bottom of the cylindrical container can produce horizontal pressure gradient within the Ekman layer, and consequently the interior also attains the same pressure gradient that produces geostrophic interior circulation. In order to keep free surface during the local-surface cooling, a side-wall cooling method is suggested. For the various type of local forcing including the effects local cooling and the periodic change of local wind-stress curl, western-boundary flow in terms of its strength, position of separation from the boundary have been observed.

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