The Theory of Extrusion

Bishop, Justin

doi:10.1179/mtlr.1957.2.1.361

Cited by 4 publications

(2 citation statements)

References 5 publications

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“…They suggested that the pressure for plane strain and axisymmetric extrusions for equal reductions of area might be expected to be approximately the same. This suggestion was argued by Johnson [11] and Bishop [12], who presented empirical formulas for extrusion pressure. The upper bound approach was applied by Avitzur [5] to compute the energies expended in wire drawing and extrusion through a rigid conical die and by Osakada and Nimi [13] to calculate the extrusion pressure for the radial flow field through a conical die for a rigid perfectly plastic material.…”

Section: Introductionmentioning

confidence: 96%

Plastic flow in extrusion and drawing through conical and wedge-shaped dies: Prediction of central bursting

Samy

Saleh

Ragab

2006

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this article, the plastic flowfields for extrusion and drawing - for rigid plastic materials forced through conical and wedge-shaped dies - are analysed on the basis of Shield's work. A modification to Shield's analysis is developed to account for the redundant deformation. Solutions for axisymmetric and plane strain flows are given. The total forces estimated for both drawing and extrusion operations are compared favourably with available experimental data. On the basis of the present modified Shield's analysis, expressions for the stresses within the die are then derived. These expressions are then employed to predict central bursting by applying two fracture criteria, namely: the hydrostatic stress criterion and the plastic instability criterion. The deformation zone geometry criterion has also been used for comparison. The predictions fairly agree with the experimental results.

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Section: Introductionmentioning

confidence: 96%

Plastic flow in extrusion and drawing through conical and wedge-shaped dies: Prediction of central bursting

Samy

Saleh

Ragab

2006

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…After a steep increase, the temperature graph flattens out, and then remains flat during the stroke, or it may increase all the time, eventually drop down towards the end of the stroke, after having passed over a maximum value. As regards temperature determined by theory, already in 1956, Bishop 5 showed the presence of a hot spot in the extrusion metal at the entrance to/ in the die bearing, by calculation and drawing of iso-temperature lines on the longitudinal section of the billet. Numerical methods, as the finite-difference method, were later developed.…”

Section: Introductionmentioning

confidence: 99%

The hot spot in Al-rod extrusion investigated by FEM-analysis

Valberg¹,

Lefstad

Costa

2019

AIP Conference Proceedings

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FEM-analysis is applied to study thermo-mechanical conditions in an industrial Al-rod extrusion process using long billets as stock material. In the analysis, focus is on the conditions in the hot spot present inside the metal of the billet material near to the die edge during extrusion. Here the strain-rate and the temperature in the hot zone reaches critical conditions if the extrusion ram speed is set too high. When overcritical conditions exist here, speed cracking will occur in the metal. The Lagrangian version of the software DEFORM 3D is applied to model the process numerically, and it is investigated how the distribution of the temperature as state-variable is predicted in the hot spot and else how inside the billet, and how it depends on the extrusion conditions. Through the analysis, new information on this important issue is achieved.

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Extrusion Theory and Calculations

Backofen¹

1961

JOM

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The Theory of Extrusion

Cited by 4 publications

References 5 publications

Plastic flow in extrusion and drawing through conical and wedge-shaped dies: Prediction of central bursting

Plastic flow in extrusion and drawing through conical and wedge-shaped dies: Prediction of central bursting

The hot spot in Al-rod extrusion investigated by FEM-analysis

Extrusion Theory and Calculations

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