Transactions of Materials Processing (소성∙가공)

The Korean Society for Technology of Plasticity and materials processing (한국소성∙가공학회)
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Effect of Punch Design and Flow Stress on Frictional Calibration Curve in Boss and Rib Test

보스-리브 시험 시 마찰보정선도에 대한 펀치형상 및 유동응력의 영향

  • 윤여웅 (한국기계연구원 부설 재료연구소 산업기술지원본부) ;
  • 강성훈 (한국기계연구원 부설 재료연구소 융합공정연구본부) ;
  • 이영선 (한국기계연구원 부설 재료연구소 융합공정연구본부) ;
  • 김병민 (부산대학교 기계공학부)
  • Published : 2009.12.01
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Abstract

Recently, boss and rib test based on backward extrusion process was proposed to quantitatively evaluate the interfacial friction condition in bulk forming process. In this test, the tube-shaped punch with hole pressurizes the workpiece so that the boss and rib are formed along the hole and outer surface of the punch. It was experimentally and numerically revealed that the height of boss is higher than that of the rib under the severe friction condition. This work is focused on the effect of the punch design and flow stress on deformation pattern in boss and rib test. From the boss and rib test simulations, it was found that there is slight variation in both the heights of boss and rib according to the length of punch land, nose radius, and face angle. However the hole diameter of the punch and the clearance between the punch and die have a significant influence on the calibration curves showing the heights of the boss and rib. In addition, the effect of flow stress on the calibration curves was investigated through FE simulations. It was found that there is no effect of strength coefficient of the workpiece on the calibration curves for estimation of friction condition. On the other hand, the strain-hardening exponent of the workpiece has a significant influence on the calibration curve.

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References

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