• Title/Summary/Keyword: Draw-bending

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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.

Springback for the Warm 2D Draw-bending of Steel Sheets (박판의 온간 2차원 드로오 벤딩에서의 스프링백)

  • Lee S. M.;Chang S. H.;Choi Y. C.;Heo Y. M.;Seo D. G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2001.10a
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    • pp.75-80
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    • 2001
  • The purpose of this study is to investigate the characteristics of springback for various process conditions of the 2D draw-bending operation. The process variables are the forming temperature, the geometry of tools such as punch profile radius(Rp) and die profile radius(Rd). Especially, in order to control the springback, the use of the warm forming method is applied. For the warm draw-bending, five steps of temperature ranges, from room temperature to $200^{\circ}C$, were adopted. And two kinds of steel sheets, namely SCP1 and TRIP(transformation-induced plasticity), the newly developed high strength Steel, were adopted. As a result, the springback was affected by the elevated temperature and the geometry of tools in two kinds of steel sheets.

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Manufacturing Technique on the U Type Draw-Bending of Inner Groove Tube (Inner groove tube의 U형 Draw-Bending 가공기술에 관한 연구)

  • Kang, H.S.;Kim, D.S.;Hur, S.;Hong, S.I.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.148-151
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    • 2003
  • The purpose of this study is to investigate the manufacturing technique on the U type Draw-Bending of inner groove tube. The U type tube requires the quality of product that satisfy sufficient conditions for a heat exchanger. The mandrel components act the important roles that prevent wrinkles and keep the shape of cross section of bended tube at bending process. We performed the FEM simulation using LS-DYNA software and the bending test of inner groove tube and then, compared bending simulation with bending test results about mandrel ball diameter, mandrel position and optimal clearance between mandrel and tube.

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Springback in Warm Forming of Aluminum Alloy Sheets (알루미늄 합금박판 온간 성형의 스프링백)

  • 한병엽;정기욱;금영탁
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.152-155
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    • 2003
  • In order to examine the springback of aluminum alloy sheets, AL1050 and AL5052, in the warm forming which forms the sheet above room temperature, the stretch bending and draw bending tests in various working temperatures were carried out. While the springbacks of AL5052 and AL1050 are tremendously reduced over 150$^{\circ}C$ in the stretch bending test, the springbacks in the draw bending test are rapidly reduced in 150$^{\circ}C$-200$^{\circ}C$ for AL5052 and 200$^{\circ}C$-250$^{\circ}C$ for AL1050. Using the FEM program, the forming and springback processes are analyzed. Though springback amounts of analysis result are slightly bigger than those of experiment, they showed the same trend in the decreasing springback as the forming temperature increases.

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A Study of Bending Process for Development of Subframe by Hydroforming (일체화 성형 서브프레임 개발을 위한 벤딩 공정의 영향성 연구)

  • 서창희;이우식;김헌영;임희택
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.262-265
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    • 2003
  • In the present study, subframe was developed using hydroforming technology. The manufacturing process for subframe consists of tube bending, pre-forming and hydroforming. The effects of bending process for manufacturing hydroformed subframe were researched. And the variables of bending process were studied by FEM simulation. The bending method is rotary draw bending that is the most popular, cost-effective bending method for thin walled tubes.

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Analytic Factor Effects Analysis of Bending Process of Double Pipe for Tube-Hydroforming using Experimental Design (실험계획법을 이용한 튜브 하이드로 포밍용 이중관 벤딩 공정의 해석적 요인 효과 분석)

  • Shim, D.S.;Jung, C.G.;Seong, D.Y.;Yang, D.Y.;Park, S.H.;Kim, K.H.;Choi, H.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.310-313
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    • 2007
  • This paper covers finite element simulations to evaluate the bending limit of double pipe for tube-hydroforming. The tube-hydroforming process starts with a straight precut tube. The tube is often prebent in a rotary draw bending machine to fit the hydroforming tool. During the bending the tube undergoes significant deformation. So forming defects such as wrinkling, thinning and flattening are generated in the tube. Consequently we analyzed the effect of process parameters in rotary draw bending process and searched the optimized combination of process parameters to minimize the forming defects using orthogonal arrays. The characteristic to evaluate the effects of the process parameters is the bending angle which wrinkling is generated, we define the bending angle at that time as bending limit. Of many process parameters, the process parameters of the bending process such as gab between inner and outer tube, boosting force, dimensions of mandrel were analyzed. And we observed the deformation modes of bent double pipe at specific bending angle in each parameter combination.

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Development of Finite Element Program for Analyzing Springback Phenomena of Non-isothermal Forming Processes for Aluminum Alloy Sheets(Part 1 : Experiment) (알루미늄 합금박판 비등온 성형공정 스프링백 해석용 유한요소 프로그램 개발 ( 1부 : 실험 ))

  • 금영탁;유동열;한병엽
    • Transactions of Materials Processing
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    • v.12 no.3
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    • pp.202-207
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    • 2003
  • In order to examine the springback amount and material properties of aluminum alloy sheets (AL1050 and AL5052) in the warm forming which forms the sheet above the room temperature, the stretch bending and draw bending tests and tensile test in various high temperatures are carried out. The warm forming temperature 15$0^{\circ}C$ is a transition in terms of the material properties: over the forming temperature 15$0^{\circ}C$, them $\sigma$$_{YS}$ , $\sigma$$_{TS}$ , E, K, n, etc. are bigger but $\varepsilon$ and plastic strain ratio are smaller. Below the forming temperature 15$0^{\circ}C$, there are no big differences in material properties as the forming temperature changes. AL5052 sheet has more springback effect than AL1050 sheet. While the springbacks of AL5052 and AL1050 sheets show a big reduction over the warm forming temperature 15$0^{\circ}C$ in the stretch bending test, the springback rapidly reduces in the warm forming temperature 15$0^{\circ}C$-20$0^{\circ}C$ for AL5052 sheet and 20$0^{\circ}C$-25$0^{\circ}C$ for AL1050 sheet in the draw bending test.

Experiments for Forming Limit Diagram and Springback Characteristics of AZ31B Magnesium Alloy Sheet at Elevated Temperature (AZ31B 마그네슘 합금판재의 온간 성형한계도 및 스프링백 특성 시험)

  • Choi, C.S.;Lee, H.S.;Kim, H.J.;Lee, K.T.;Kim, H.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.289-293
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    • 2007
  • The effect of temperature on the forming limit diagram was investigated for AZ31B magnesium alloy sheet through the limit dome height test in the range from room temperature to $300^{\circ}C$. The formability of AZ31B sheet was improved significantly according to the increasing temperature. Also we studied the springback characteristics through the 2D draw bending test with different blank holding forces at elevated temperatures. Springback quantity was considerably reduced as temperature went up. The blank holding force in the range used, however, had little influence on springback. Experimental results obtained in this study may provide a material database for AZ31B sheet.

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