Extrusion Of Sections Research Articles

Development and application of rock breaking platform with variable cross section extrusion pulsed water jet

Development and application of rock breaking platform with variable cross section extrusion pulsed water jet

An Applied Analytical Method for the Forward Extrusion of Metals

An applied analytical formulation was developed to deal with the forward extrusion of non-symmetric sections based on the upper bound method. This method of solution has been developed as an alternative to finite element method with the advantages of less time consumption and expense. The deforming region where the material flow occurs was formulated in a new and more realistic fashion by streamlines and stream surfaces. Streamlines and stream surfaces were defined parametrically for the material flow and the development of the kinematically admissible velocity field. The newly developed velocity field incorporated features such that the real physical aspects of the problem were followed more closely than before. The internal, shear and frictional power terms were obtained from the upper bound solution. Using the present method of analysis, the pattern of material flow and the relative extrusion pressure were computed. Results compared to previous works indicated substantial improvements. Experimental and numerical investigations were carried out, and the proposed theoretical model was verified. Close agreement was observed between the analytical results and those from the simulation and the experiment.

Tests of perforated aluminium alloy SHSs and RHSs under axial compression

This paper presents an experimental investigation on a wide range of aluminium alloy stub, intermediate and slender columns containing multiple circular openings. Three series of compression tests including six different cross-section dimensions of columns with different lengths were conducted by applying uniform axial load to the pin-ended specimens, which were fabricated by extrusion of square and rectangular hollow sections (SHS and RHS) using 6061-T6 and 6063-T5 heat-treated aluminium alloys. In test series I, the specimens were fabricated by welding aluminium alloy plates at both ends of the columns for pin-ended compression tests. In test series II, the specimens were further reinforced by carbon fiber-reinforced polymer (CFRP) at the heat-affected zone resulted from the welding. In test series III, the special aluminium alloy sleeves were designed instead of welding at both ends of the columns to preclude the form of the heat-affected zone. The column strengths, failure modes, load versus axial shortening curves, and strain distributions along the circular openings of test specimens were all obtained from the experimental investigation. In addition, the test strengths of aluminium alloy SHS and RHS columns with or without openings were compared with the design strengths calculated using the design rules given in the current design guidelines. It is shown from the comparison that the first design method proposed by Zhu and Young for aluminium alloy SHS and RHS welded columns is comparatively appropriate for the design of aluminium alloy SHSs and RHSs under axial compression. Whereas, the current design rules for cold-formed steel structural members with openings may be inapplicable to the design of perforated aluminium alloy SHSs and RHSs under axial compression.

A Procedure for Determining Force/Power Parameters of the Conform Process with Prechamber

The subject of analysis is the real process of continuous extrusion of copper section on a Conform machine with a prechamber. The machine is operated at the Kamensk-Uralsky Non-Ferrous Metal Working Plant. Perlin’s method is used, which involves determining the total pressing force, to calculate the following stability-critical parameters of the Conform process: the length of the split container (which should be such that the frictional force on its movable surface be sufficient for extruding the metal from the prechamber to the die hole), the wheel torque, the power of the electric motor. Comparing the calculated and measured data shows that the discrepancy is less than 8%. The derived equations are simple and easy to use in technical and technological design of the Conform process with prechamber, which is exactly the purpose of this study.

Mathematical Analyses and Numerical Simulations for Forward Extrusion of Circular, Square, and Rhomboidal Sections From Round Billets Through Streamlined Dies

In the present investigation, an analysis using three-dimensional upper-bound method based on continuous velocity filed has been carried out for the extrusion of circular, square, and rhomboidal sections from round billets. The die surface representation in the present work could easily be applied to the extrusion of many different shapes just by defining the functions that describe the entry and exit sections and putting them into the general formulation. The die profile was tested for the third- and fifth-order polynomial functions. The extrusion process is also simulated using the finite element code, ansys (V 14.0), in order to assist the mathematical solution and to show the stress and strain distributions for the products when the strain hardening effect is taking into the account. Effects of friction, shape complexity, reduction of area, and die length on the extrusion pressure were also investigated. The results obtained in this work were compared with the theoretical results of other workers and found to be in highly compatible.

Die Profile Optimization of Rectangular Cross Section Extrusion in Plane Strain Condition Using Upper Bound Analysis Method and Simulated Annealing Algorithm

Extrusion die profile has a significant role on material flow characteristics, product microstructure, die life, and required load. Nowadays, economic requirements and effort to improve and homogenize metallurgical product properties have compelled the researchers to modify the conventional constant angle extrusion dies by employing streamlined die profiles. In the present research work, an optimum plane strain extrusion profile has been presented through implementation of upper bound analysis and Bezier curve in a simulated annealing (SA) algorithm to minimize the process force and its redundant work. The effect of material properties, friction conditions, reduction of area, and cross-sectional ratio on the optimum die profile is considered. The results of finite-element simulation proved that utilizing the optimum curved die instead of the constant angle die is superior regarding the decrease of the maximum required force, 10.5%, and the product inhomogeneity factor (IF), 50%. In addition, based on stress analysis of die/work piece interfaces, it is expected that the die life of optimal curved dies be longer than that of the optimum constant angle dies. Also, it has been demonstrated that the material work hardening characteristics does not have remarkable effect on the optimum curved die profile.

Continuous Rotary Extrusion (CRE) of Flat Sections from 6063 Alloy

The study relates to a process of continuous rotary extrusion (CRE), also known under the name of a Conform Process. This method is used more and more extensively for the plastic working of metals and alloys. In CRE, the feedstock is fed into a profiled groove on the rotating extrusion wheel and is pressed by the pressing wheel. The friction of the extruded material against the rotating wheel generates a force that is pushing the material into the deformation chamber followed by extrusion through the die orifice. The extrusion by CRE was performed on an MC-260 device supplied by Meltech-Confex and installed at IMN - OML for processing of the 6063 aluminium alloy. The feedstock was composed of annealed rods. Two parameters were controlled during extrusion: the temperature of the shoe (element of the housing pressing the extruded material to the wheel) and the speed of the driving wheel. The 6063 alloy was extruded using the wheel speed of 2, 5, 10 and 15 rpm and the shoe temperature of 90°C and 105°C. The extruded flat sections were examined visually for continuity and quality of the resulting surface. In the feedstock rod and in the extruded flat sections (before and after heat treatment), the microstructure and grains were examined by light microscopy. Mechanical properties were also determined (static tensile test and hardness measurement). The study shows how the structure and the mechanical properties of the extruded flat sections are changing depending on the extrusion parameters applied. From the 6063 alloy rods extruded by CRE, flat sections of satisfactory quality were obtained. It was found that CRE yields the highest mechanical properties combined with the correct structure and high surface quality when the feedstock is extruded with the wheel rotational speed of 10 rpm and the shoe temperature of 105°C.

3D profile modelling and accurate representation of the deforming region in the extrusion process of complex sections using equi-potential lines method

The deforming zone in the die determined by the cross-sectional shape of the final product plays a key role in the extrusion process affecting the extrusion pressure and product quality. Therefore, prediction of the optimal profile of the deforming region is the main objective for an effective extrusion process. In this study, using the analogy between the conventional plasticity theorem and electrostatics, the notion of equi-potential lines (EPLs) was applied to accurate representation and 3D design of the deforming region in the extrusion process of a complex section. To implement the analogy in the extrusion, the initial and final shapes were considered, and two different potentials were assigned between the inlet and outlet surfaces. Then, the EPLs were drawn that show the minimum work path between the entry and exit sections. The drawn EPLs were connected to build up a 3D-profile for the deforming region in the extrusion process. In addition, the EPLs were used in accurate representation of the deforming region using high-order polynomial curves. The effectiveness of the proposed method was examined using a complex section (U-shaped) from the literature. Then, the extrusion pressure for different profiles in the deforming region was analyzed numerically and experimentally. Moreover, the obtained polynomial curves were used in the upper bound (UB) solution for prediction of the extrusion pressure. There were reasonable agreements between the analytical, numerical, and experimental results. An acceptable reduction in the extrusion pressure for 3D modelling of the deforming region with the EPLs was reported. It was shown that the EPLs could be used for accurate representation of the deforming region in the extrusion of complex sections.

On the minimization of the exit profile curvature in extrusion through multi-hole dies: a methodology and some verifications

In this study, a methodology has been presented for radial positioning of the die holes in multi-hole extrusion of non-symmetric sections. The objective of radial positioning is to minimize exit profile curvature. For this purpose, a two-hole die with non-symmetric T-shaped holes has been investigated. A kinematically admissible velocity field at deformation zone has been developed. The deformation region includes the dead metal zone (DMZ) which is assumed to be linear. The DMZ length was obtained by energy minimization through the upper bound method. To predict the exit profile curvature a deviation function has been suggested. Using the proposed function, the velocity field has been used for prediction of the exit profile curvature and thereby positioning of the die holes. The predictions of the proposed methodology were validated with physical modeling. With little development, this methodology could be applied to dies, which have more holes and/or generate profiles that are more complex. This will help die designers enhance the quality of extrusion process.

Extrusion of sections by immuring technique

To improve homogeneity in extrusion of sections, extrusion of aluminium by an immuring technique using lead has been studied. In steady state extrusion, the immuring material is trapped in a triangular region surrounded by a die wall, a container wall and a deforming billet, and behaves like a part of an extrusion die. The flow pattern obtained by this technique is far more homogeneous than that by using the conventional technique, and also the extrusion load is 20% lower than that by the conventional technique. The profile of the withdrawn billet can be regarded as the optimum die profile required. The profile determined in this way is very close to the theoretical optimum profile. This experimental technique can also be used to determine the die profile for the near homogeneous internal deformation.

Model-based controlling of extrusion process

Functional data analysis (FDA) is a statistical method applicable in various areas of human activities. This method allows the prediction of different process parameters based on input data that are continuously recorded during the manufacturing. The present study shows how exit section temperature in the direct extrusion of aluminum sections can be predicted enabling ram speed adjustment to obtain isothermal extrusion. A new linear regression mathematical model has been proposed for the prediction of extrudate temperature. The mathematical model has been developed using technological extrusion parameters that were measured and recorded on the real extrusion press. Simulation of the mathematical model shows that its predictions are in good accordance with the measured data on the extrusion press. In order to obtain isothermal extrusion, adequate ram speed curve was calculated from the proposed mathematical model.

METAL FLOW DURING EXTRUSION OF NON-CIRCULAR SECTIONS

The paper presents the analysis of nature of metal flow during extrusion of non-circular sections and determining the relationship between extrusion force and geometrical parameters of extrudate (the shape of the extrudate). Experimental procedure was curried out for the simplest cases of non-circular profiles (triangle, square, rectangular) of various geometrical parameters. The extrusion load and punch displacement have been registered during experimental work. By determining parameters of metal plastic flow (the depth of plastic zone Lp and the dead zone angle sm) it has been shown the difference in nature of metal flow during extrusion product differing in non-circular sections. This differentiation results in the complex nature of flow consequential from change with circular section of the billet to non-circular section of extrudate.It has been shown that flow resistance can be different with regard to appearing configurations of deformation zones (the size and shape of plastic zone, dead and shear zones) and dependent from for example geometrical parameters of a die (shape and size of an die orifice).

An analytical formulation as an alternative to FEM software giving strain and stress distributions for the three-dimensional solution of extrusion problems

A new improved analytical method based on the upper bound theorem is presented for the solution of extrusion problems. This method has been formulated in such a way as to eliminate the deficiencies in the previous works in order to enable it as a powerful analytical tool as an alternative to finite element software. The proposed formulation is a general method of solution, which could be used for the analysis of many bulk forming processes. However, in this paper, the forward extrusion of a square section from a round billet has been presented as an example. Kinematically admissible velocity fields were computed which gave a more physically realistic material flow patterns as compared to previous works. The distribution of strain and stress as well as the results for the effect of process parameters on the extrusion load and die geometry was also given. These results were compared with FEM data to observe the accuracy and effectiveness of the present method. For the extrusion of square sections from round billets, detailed analysis of strain distribution on the exit section was carried out using the components of the power due to internal deformation, interface friction, and velocity discontinuities at the entry and exit surfaces. Comparison with experimental data was made, and verification of the theoretical results was carried out. The improvement of the results computed using the present method was shown by comparison with the previous works.

A new analytical definition of the dead material zone for forward extrusion of shaped sections

This article aims to provide a new formulation for the analysis of the extrusion process for non-axisymmetric sections. The upper bound theorem has been used to obtain a generalized kinematically admissible velocity field. The geometry of the deforming region has been formulated considering variation of the dead zone size at different angular positions and three-dimensional curved surfaces have been employed to define the entry and exit surfaces of the deformation zone. Using this analytical method, extrusion of square, rectangular and L-shaped sections were analyzed and the effect of shape complexity on material flow and dead material zone (DMZ) formation under different conditions has been investigated. Physical modelling experiments and finite element analysis were carried out to reveal the capability of the proposed theoretical method.

Development of a more realistic upper bound solution for the three-dimensional problems in the forward extrusion process

This paper provides a new generalized formulation based on the upper bound method for the three-dimensional analysis of the forward extrusion of non-symmetrical sections. The proposed method has been formulated in such a way as to present a more realistic definition of deforming region by eliminating internal discontinuities and also velocity discontinuities at the entry and exit surfaces which are defined by three-dimensional curved surfaces. Using this new formulation, extrusion of shapes such as L-shape, rectangle, hexagon and a spur gear was analyzed. The distribution of velocity and strain, three-dimensional material flow as well as extrusion load were obtained. Finite element analysis for the same problem was also carried out and the comparison of the results showed the capability of the present method. In fact, the results of the analytical velocity and strain distributions are in close agreement with those given by the simulation in terms of magnitude and distribution. Influence of the process parameters such as extrusion ratio and aspect ratio on the strain distributions was investigated. Comparison between theoretical and experimental data was carried out and close agreement was observed. Also, improvements of the results of the present method were observed comparing with previous works.

Effect of die inlet geometry on extrusion of clover sections through curved dies: Upper bound analysis and experimental verification

The effect of die inlet and transition geometry on the extrusion loads and material flow for extrusion of clover sections were investigated and presented both theoretically and experimentally. For this purpose, four different die geometries including straight tapered and cosine transition profile and each of them having round and clover inlet geometries were chosen. In the experimental study, commercially pure lead was used because of its hot forming characteristic at room temperature. A newly kinematical admissible velocity field to analyze different profiles of extrusion dies of clover section from round bars was proposed by upper bound analysis. It is clear that the extrusion loads obtained from the theoretical analysis for various die inlet-die transition geometry combinations are in good agreement with the experimental results. Axis deviations of the parts which define the dimensional quality of the products were also investigated.

FEM Analysis of Extrusion of Triangular Sections from Round Billets through Curved Dies

The curved die plays a significant role in reduction of extrusion load, refinement of microstructure and improvement in quality of product. In the present investigation, a numerical FEM modeling has been carried out for extrusion of triangular section from round billet through a curved die using DEFORM-3D software for steady state deformation using rigid plastic material. The extrusion load has been predicted. The effective stress, strain, strain rate velocity and temperature distribution have been determined. An experimental test rig has been fabricated. The experimental results are compared with the theoretical results. The results of computations are found to be in good agreement with those of the experiments.

Theoretical and Experimental Analyses for the Forward Extrusion of Nonsymmetric Sections

A new generalized formulation for the analyses of the forward extrusion of nonsymmetric sections is presented in this article. In the formulation presented by the authors it is assumed that all points on the cross-section of the initial billet map to similar points on the final section of the extruded profile. The division of deforming region into subsections is done in such a way so that the theoretical concept for the material flow follows the real situation more closely than was done in previous works. This procedure provides a simpler and better way to tackle the extrusion of nonsymmetric shapes and could be used for shapes that could not been analyzed before. Based on the new formulation upper bound solutions were obtained. Using the present analysis the positioning of the die cavity was also optimized. Dies were designed and manufactured for the nonsymmetric C section profile, and experiments were carried out. Theoretical results were obtained for the extrusion pressure, force, optimum die length, and the influence of friction and reduction of area were investigated. Theoretical and experimental data were compared, and close agreement was observed. Also comparing the previous works with the present method, improvements on upper bound values were observed.

A universal formulation for the extrusion of sections with no axis of symmetry

The subject of theoretical analysis for the extrusion of profiled sections has been heavily worked on by many researchers. However most of these have concentrated on the extrusion of sections with some axes of symmetry. This paper aims to provide a new formulation for the analysis of the extrusion process for non symmetric profiled sections with no axis of symmetry. The upper bound theorem has been used to obtain an approximate solution. Both flat faced dies and bilinear dies were used in the present work. In fact this formulation could be applied to the extrusion process of hollow sections as well as solid parts. The advantage of the proposed method is the new way of discretizing the deforming region in the extrusion of shaped sections based on which a generalized kinematically admissible velocity field was formulated. For a given extruded profiled section this method employs fewer number of sub-divisions than before, giving a lower upper bound value for the extrusion power. The generality, easy application to different sections, short computing time and fairly realistic outcomes of the analysis could be regarded as other strengths of the present method. The lack of incorporation of temperature effects for hot extrusion processes could be mentioned as one of the disadvantages of the present method. The position of the die cavity was also optimized using the new method. A design map for the extrusion die geometry was also given as a graph of extrusion pressure versus the optimum die length for the bilinear dies with different frictional conditions and reductions of area. The extrusion of L-shape profiled section was chosen as a sample since it had no axis of symmetry. Extrusion dies were also manufactured and experiments carried out to verify the theoretical results. Finite element simulation for the extrusion of U, T and I-shape profiled sections was also carried out using ABAQUS\\CAE\\Explicit commercial software.

Elastic Deformation Predicting Design and Numerical Simulation for an Asymmetry Multi-Mandrel Aluminum Extrusion Die

Detail analysis is presented for the influence of elastic deformation on profile wall thickness, the metal flowing and stress load situation of an asymmetry multi-mandrel die. Through the combination of numerical simulation and traditional experimental design, the method on complex section extrusion dies by quantitative prediction of the elastic deformation situation, can improve the accuracy and success rate effectively. In addition, profiles can be extruded stably when the exit velocity fluctuation is under a corresponding range. Under this range, deformation stress caused by uneven metal flowing is under the critical stress, which relates to the thickness to width ratio t/b.