Journal of the Korean Society for Precision Engineering (한국정밀공학회지)

Korean Society for Precision Engineering (한국정밀공학회)
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Analysis of the Corner Cavity of Axisymmetric Backward Extrusion by the Upper Bound Approach

상계해석을 이용한 축대칭 후방압출 공정의 Corner Cavity 해석

  • 박재훈 (부산대학교 정밀기계공학과 대학원) ;
  • 변홍석 (부산대학교 정밀기계공학과 대학) ;
  • 김영호 (부산대학교 기계기술연구소)
  • Published : 2000.02.01
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Abstract

In this paper, the formation of a corner cavity in the final stage of axisymmetric backward extrusion process is studied by means of upper bound analysis using kinematically admissible velocity. The quantitative relationships between corner cavity formation and process parameters are studied. And analytical results are compared with those of experiment to which plasticine is used. It is found that the analytical results agree well with experimental one. In addition, to restrict the formation of a corner cavity, driven container is applied to backward extrusion and the results are compared with those of FEM. The critical thickness of the bottom of the billet decreases with increase in reduction of area, and increases with decrease in friction. To prevent the formation of corner cavity, the concept of moving container was applied. Throughout this process, the occurrence of a corner cavity is delayed and forming limit area is enlarged.

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References

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