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Prediction of the Dead Metal Zone for Determination of the Exit Curvature Profile in the Extrusion of Non-Symmetrical Flat

Rastegar Borkhyli, Meysam | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42626 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Assempour, Ahmad
  7. Abstract:
  8. The extrusion process of flat dies in non-symmetrical sections is among processes which in spite of enormous applications, has not been thoroughly understood due to complexities of analyzing the section deformation process. In these dies, a zone is formed during egression of billet from die in which the material is stationary and accordingly the material on profile of this zone shears. This zone is called the dead metal zone. Dead metal zone is a natural non-linear die and it is pragmatic to obtain the value of the deviation. In the present work, determine the curvature of the exit profile by using prediction of the dead metal zone profile is target. The dead metal zone profile is assumed based on Hermite cubic spline. To determination of geometrical parameters of the dead metal zone curve, this fact that material tends to use minimum energy is used. First the velocity field near actually velocity is calculated. Subsequently, the required power for the process is estimated using the upper bound method. The coefficients of the curve are set so as to minimize the consumed power. Finally, using estimation of this curve, the value of the exit profile curvature is estimated. Dead zone and exit profile curvature results for non-symmetrical T-shape and U-shape dies with known off-centric and dimentions compared with the results acquired from finite element software simulations (ABAQUS v6.9) and (Deform-3D v5) and physical modeling. The analytical results are in good agreement with results of the finite element simulations and physical modeling
  9. Keywords:
  10. Direct Extrusion ; Exit Curvature Profile ; Upper Bound Method ; Flat Die ; Dead Metal Zone

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