Amin Samadi Ghoushchi; Caren Abrinia; Mohammad Kazem Besharati Givi
Abstract
Slab method of analysis has been used for solving metal forming problems for a long time. However it has been restricted to plane strain and axisymmetric problems due to limitations in its formulations. In this paper a new formulation has been proposed so that it could be applied to three dimensional ...
Read More
Slab method of analysis has been used for solving metal forming problems for a long time. However it has been restricted to plane strain and axisymmetric problems due to limitations in its formulations. In this paper a new formulation has been proposed so that it could be applied to three dimensional problems in metal forming. A parametric slab has been considered in this analysis and the force balance on the slab was carried to obtain equilibrium equations in terms of these parameters. The parameters in fact are related to the geometry of the final extruded shape, the die and the material flow regime assumed in the formulation. In this way most of the limitations encountered in previous formulations were surpassed. The effect of reduction of area, frictional conditions and other process parameters on the extrusion pressure was investigated. The theoretical results obtained in this paper were compared with the results of finite element method and a good agreement was observed between them.
Caren Abrinia; Rahim Tahriri Masoule
Abstract
Many metal forming problems have been solved using the slip line field method but all of them have either been two-dimensional (plane strain or plain stress) or axisymmetric problems. In this paper a procedure has been proposed by which the slip line field solution to three dimensional problems of metal ...
Read More
Many metal forming problems have been solved using the slip line field method but all of them have either been two-dimensional (plane strain or plain stress) or axisymmetric problems. In this paper a procedure has been proposed by which the slip line field solution to three dimensional problems of metal forming becomes possible. For this purpose the extrusion of shaped sections has been taken as a case study. For this problem the geometry of the deforming zone has been defined by streamlines and stream surfaces. Clearly for the three dimensional extrusion of shaped sections the stream surfaces are not plane surfaces, and on the other hand the slip line field formulation could only be applied to plane surfaces, therefore an approximation has been made to accommodate this difficulty. In fact the three dimensional surface has been approximated to a plane surface so that for each three dimensional stream surface there exists an approximate plane surface. Unlike the case for the axisymmetric problem where there was only one plane surface on which the formulation was defined and the revolved 360 degrees to complete the deforming zone here there are many plane stream surfaces that by summing them up together the deforming zone is defined. The slip line field formulation was then applied to each and every one of these surfaces and the extrusion pressure on each surface was calculated separately and by adding up all the components of the pressure on each surface the total extrusion pressure was obtained.
To account for the error evolved from the approximations made in the formulations, error functions were developed which showed how much error was developed due to the approximations. To verify the results comparison were made to the results obtained by upper bound and experimental methods. These comparisons showed very good agreements.
Caren Abrinia; Jalal Pour Hosseini Baboddashti
Abstract
In this paper the eccentric forward extrusion of sections has been simulated and analyzed using FEM Abaqus-explicit. The results have been compared to those obtained from upper bound theorem and experimental works. Close agreements was observed between the FEM and experimental work and as compared with ...
Read More
In this paper the eccentric forward extrusion of sections has been simulated and analyzed using FEM Abaqus-explicit. The results have been compared to those obtained from upper bound theorem and experimental works. Close agreements was observed between the FEM and experimental work and as compared with the upper bound data more realistic and better predictions were made by the authors’ method. The sections considered in this work were circular and square shaped cross sections. Process parameters such as die length, friction factor and percentage of eccentricity have been investigated and their influence on the relative extrusion pressure and the curvature of the extruded profiles has been illustrated. The effect of die profile has also been studied and shown that a 10 percent reduction in the extrusion pressure could be achieved by using the optimum die profile.
