• Title/Summary/Keyword: Sheet Metal Friction Test

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Friction Model for Sheet Metal Forming Analysis (Part1 : Experiment) (박판성형 해석용 마찰모델 (1부 : 실험))

  • 이봉현;금영탁
    • Transactions of Materials Processing
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    • v.11 no.4
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    • pp.349-354
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    • 2002
  • In order to find the effect of lubricant viscosity, sheet surface roughness, tool geometry, and forming speed on the frictional characteristics in sheet metal forming, a sheet metal friction tester was designed and manufactured and friction test of various sheet were performed. Friction test results showed that as the lubricant viscosity becomes lower, the friction coefficient is higher. When surface roughness is extremely low or high, the friction coefficient is relatively high. The result also show that as the punch radius and punch speed becomes bigger, the friction coefficient is smaller. Using experimental results, the mathematical expression between friction coefficient and lubricant viscosity, surface roughness, punch comer radius, or punch speed is also described.

Experimental Study on Frictional Characteristics of Sheet Metal Forming (박판성형 마찰특성의 실험적 연구)

  • 금영탁;이봉현;차지혜
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2002.05a
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    • pp.54-57
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    • 2002
  • In order to find the effect of lubricant viscosity, sheet surface roughness, tool geometry, and forming speed on the frictional characteristics in sheet metal forming, a sheet metal friction tester was designed and manufactured and friction tests of various sheets were performed. Friction test results showed that as the lubricant viscosity becomes lower, the friction coefficient is higher. When surface roughness is extreme1y low or high, the friction coefficient is high. As punch comer radius and punch speed are bigger, the value of friction coefficient is smaller. The sensitivity of friction coefficient is mainly governed by lubricant viscosity and sheet surface roughness.

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A Cup Drawing Test for Measuring the Coefficient of Friction in Sheet Metal Forming (컵드로잉에 의한 판재의 마찰특성 평가)

  • Kim, Y.S.;Choi, W.J.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.1
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    • pp.96-105
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    • 1994
  • Cup drawing tests were performed to evaluate the friction characteristics of sheet metals. The linear relationship between drawing force and blank holding force obtained from the cup drawing test was used to calculate the coefficient of friction of the sheet metal. The friction coefficient was compared to that from conventional draw bead friction test. It was clarified that the cup drawing test can be used as a simple and convenient method for evaluating the friction characteristic of the sheet metal and also lubricity of the lubricant used.

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Effects of Blank Holding Force on Friction Behavior in Sheet Metal Forming (박판성형 마찰거동에 미치는 블랭크 홀딩력의 영향)

  • Shim, J.W.;Keum, Y.T.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.394-396
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    • 2007
  • In this study, in order to see effect of the blank holding force on the friction behavior in the sheet metal forming, a sheet metal friction tester is designed and manufactured, which can measure friction forces in various forming conditions, such are lubrication, die roughness, drawing speed, radius of die corner, blank holding force, etc., and performed the friction test in which friction coefficients in various blank holding forces and pulling speeds are calculated using Coulomb's friction law. The friction test reveals that friction coefficient decreases maximum 30% as the blank holding force and the drawing speed are increased to 2.5kN and 1500mm/min, respectively.

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Friction Model for Finite Element Analysis of Sheet Metal Forming Processes (박판 성형공정 유한요소 해석용 마찰모델)

  • Keum Y.T.;Lee B.H.
    • Transactions of Materials Processing
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    • v.13 no.6 s.70
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    • pp.528-534
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    • 2004
  • In order to find the effect of lubricant viscosity, tool geometry, forming speed, and sheet material properties on the friction in the sheet metal forming, friction tests were performed. Friction test results show that as the lubricant viscosity becomes lower, the friction coefficient is higher. When surface roughness is extremely low or high, the friction coefficient is high. The bigger die corner radii and punch speed are, the smaller is the friction coefficient. From the experimental observation, the friction model which is the mathematical expression of friction coefficient in terms of lubricant viscosity, roughness and hardness of sheet surface, punch corner radius, and punch speed is constructed. By comparing the punch load found by FEM using the proposed friction model with that obtained from the experiment in 2-D stretch forming, the validity and accuracy of the friction model are demonstrated.

Effects of Blank Holding Force on the Friction Behavior in Sheet Metal Forming (박판성형 마찰거동에 미치는 블랭크 홀딩력의 영향)

  • Shim, J.W.;Keum, Y.T.
    • Transactions of Materials Processing
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    • v.16 no.5 s.95
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    • pp.381-385
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    • 2007
  • In order to examine the effect of the blank holding force on the friction behavior in the sheet metal forming, a sheet metal friction tester is designed and manufactured, which can measure friction forces in various forming conditions such as lubrication, die roughness, drawing speed, radius of die corner, blank holding force, etc., and the friction tests are performed, in which friction coefficients in various blank holding forces and pulling speeds are calculated using Coulomb's friction law. The friction test reveals that friction coefficient decreases as the blank holding force, the drawing speed and lubricant viscosity increase together or individually.

Comparison of Friction Coefficients of Sheet Materials in Various Deformation Modes (변형모드별 판재의 마찰특성 비교)

  • Kim, Young-Suk;Kim, Ki-Soo
    • Transactions of Materials Processing
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    • v.3 no.1
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    • pp.51-62
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    • 1994
  • Cup drawing test and U-bending test were performed to evaluate the friction characteristics of sheet materials for the different deformation modes involved in stamping process. The coefficient of friction calculated from the each test was compared to that obtained from the draw bead friction test. It was clarified that the cup drawing test could be simply used for evaluating the friction characteristic of sheet material in deep drawing process with high contacting pressure. However the U-bending test is suitable to evaluate the frictional characteristic of sheet material in bending process with low contacting pressure.

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Study on the Calculation of Friction Coefficient for Sheet Metal Forming Analysis (박판 성형해석을 위한 마찰계수의 산정에 관한 연구)

  • Keum, Y.T.;Shim, J.W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.10a
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    • pp.27-30
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    • 2007
  • In order to measure the friction coefficient used in sheet metal forming analysis, a friction tester was manufactured and friction tests were performed in various forming conditions. Based on the friction coefficients measured, a mathematical friction model was constructed in terms of lubricant viscosity, blank holding force, punch velocity and sheet roughness. In addition, the effect of the number of forming parameters in the calculation of friction coefficient on the accuracy of sheet metal forming analysis was investigated by comparing the punch loads obtained from the FEM simulation, in which the friction coefficients were determined by a few parameters with the experimental measurement.

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Study on the Friction Model for Sheet Metal Forming (Part1:Lubrication/Surface Roughness) (박판 성형을 위한 마찰 모델에 관한 연구 (1부:윤활/표면 조도))

  • Keum Y. T.;Lee B. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2001.05a
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    • pp.24-27
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    • 2001
  • Friction between the sheet and tools is one of the important factors affecting the sheet metal forming. Therefore, the clarification of the friction is essential to improve the formability of the sheet. In order to find the effect of material property and lubricant viscosity on the frictional characteristics, tensile test, surface roughness test and friction test are performed. The results showed that friction characteristics are mainly influenced by the surface roughness and lubricant viscosity. A mathematical model of the friction is developed for calculating friction coefficient in terms of surface roughness and lubricant viscosity. The validity and accuracy of the mathematical model of the friction are verified through the experiment and FEM analysis.

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Analysis on Parameters Affecting the Friction Coefficient in Drawbead Forming of Sheet Metal (드로우비드 성형시 박판재 마찰계수 영향인자 해석)

  • Kim W. T.;Lee D. H.;Suh M.S.;Moon Y. H.
    • Transactions of Materials Processing
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    • v.14 no.8 s.80
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    • pp.668-674
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    • 2005
  • In sheet metal forming, drawbeads are often used to control uneven material flow which may cause deffets such as wrinkles, fractures, surface distortion and springback. Appropriate setting and adjusting of the drawbead force is one of the most important parameters in sheet forming process control. Therefore in this study, drawbead friction test with circular shape bead was performed at various sheets, lubricants(dry, three kinds of lubricants having different viscosities), bead materials and surface treatments of bead surface. The results obtained by drawbead friction test show that the friction and drawing characteristics of deforming panels were mainly influenced by strength of sheet, viscosity of lubricant and hardness of bead surface.