Papers by Keyword: Porthole Die

Abstract: Aiming at the aluminum profile extrusion process of a large caliber aluminum tube with porthole die, this paper established the simulation models by using finite element method and finite volume method, respectively. The extrusion process was simulated by using the above two models. The advantages and disadvantages and the applicability of the two simulation methods in simulating large aluminum profile extrusion processes were compared. It is concluded that finite volume method is more suitable than finite element method for simulating aluminum profile extrusion processes with a severe deformation. In addition, the distributions of stress and strain and the material flow patterns in the large caliber aluminum tube extrusion process with porthole die were given in detail. The results can provide useful theoretical guidelines for the process and die design as well as process parameter optimal selection for large aluminum profile extrusion processes with porthole die.

Abstract: In the paper, extrusion process of hollow aluminum profile was simulated using DEFORM-3D; the metal flow velocity of setting baffle-blocks before and after is compared. Three kinds of welding chamber depth of 10 mm, 13 mm, 15 mm were used respectively for extrusion process simulation and got die load varying pattern. Also the strain field and temperature field were analyzed. The results show that the metal flow velocity was more well-distributed by setting A、B、C、D baffle-blocks. When the weld chamber depth is 13 mm, the die load is the smallest. By analyzing the strain field and temperature field,The results showed that the major cause of metal temperature rising in the extrusion process is deformation energy generating in the process of metal plastic deformation.

Abstract: Although still having certain limitations, the numerical simulation technology has been increasingly applied to aid in optimizing the aluminum extrusion process and die design. In the present research, numerical simulations of the profiles extrusion process were performed, using the Finite Volume Method (FVM) and Finite Element Method (FEM) to make use of the individual merits of the Euler approach and Lagrange approach, respectively. The application of the simulation technology to produce large, complex profiles has, however, been quite limited. In order to solve the limited, numerical simulation of aluminum profiles with large and complicated cross-section in extrusion process was achieved using Arbitrary Lagrangian-Eulerian (ALE) approach, and non-uniform velocities at the die exit, leading to extrudate distortions, were predicted. Extrusion experiments proved that the die with the optimized design could circumvent the distortion problem. The numerical simulation technology can indeed be effectively used to reduce the number of die trials and offer the potential to realize zero die trial.

Abstract: The present study focuses on the feasibility of non-destructive testing methods for the detection of transverse and longitudinal weld seams in extruded aluminum alloys. Two extrusion trials using billet on billet extrusion with a porthole die producing both types of weld seams were conducted. First, two billets of different types of alloy, AlMgSi1 (EN AW-6082) and AlZn4.5Mg1 (EN AW-7020), were extruded. In a second trial, two billets of AlZn4.5Mg1 were processed. The produced profiles were then tested by non-destructive testing using a tactile eddy current sensor as well as an encasing sensor at room temperature. The measured signals of both sensors were then evaluated and compared. Microstructural analyses have been carried out to correlate the occurrence of transverse and longitudinal weld seams with the results of the non-destructive testing.

Abstract: This paper describes a 3D-deform simulation of porthole die extrusion process for producing harmonica-shaped tubes used for a cooling system of automobiles. Designing the related structure of the porthole die and observing the simulation results, the study was designed to evaluate the welding effect when the length of bearing exit take different values.The mean pressure and exit velocity at the welding plane are analyzed at the same time. The welding effect is determined by the mean pressure at the welding plane .The behavior of metal flow in the container is analyzed in this paper. Through the above analysis, the best structure and size can be obtained in the process of deformation so as to obtain the better machanical properties.

Abstract: The material flow in porthole dies is of crucial importance with regard to the seam weld quality in aluminum extrusion. Thus, experimental as well as numerical investigations on the effect of die geometry on the material flow were conducted. The experimental tests were performed on a 10 MN laboratory extrusion press. During the experimental trials, the extrusion ratio was varied by means of exchangeable die plates. Since the modular die allows removal of the aluminum in the welding chamber as well as in the feeders after the process, the material flow could be inspected in detail. The experimental results were used to improve the accuracy of FEA simulations, which were also conducted by commercial software. An attempt was made to improve the result quality of Eulerian FEA model regarding the simulation of an extrusion process with a gas pocket in the welding chamber. The influence of the modeling approach on the predicted material flow and on the contact pressure was analyzed and finally linked to the seam weld quality.

Abstract: Although the extrusion process is regarded as a continuous process, in practice billets are discretely loaded into the press. The joining of two consecutive billets is guaranteed by the high hydrostatic pressure of the process. Nevertheless, mechanical proprieties of the profile in the welded region are lower than those of the adjacent area thus leading to the discarding of the welded segment. Extension of the segment is mainly affected by the interaction of seam and charge welding phenomena and, nowadays, its prediction is still a tricky task involving rough empirical relations or labour intensive analyses. Aim of this work was to identify the starting and exhausting points of the charge welds evolution inside an industrial multi-profiles die, in order to determine the exact position and the minimal length to be scraped. The extrusion of four AA6060 hollow profiles through a multi-hole die were preliminary monitored in an industrial press by accurate recording of the process loads, temperatures and speeds during the process. The four profiles were sectioned starting from the ‘stop mark’ then grinded and etched in order to investigate the location and the dimension of the zone to be ridded. While the experimental activity is detailed elsewhere, this paper is focused on the finite element modelling of the process. The numerical simulation was performed by means of the Altair HyperXtrude code and predictions compared to experimental data with a particular focus on the computation of the charge evolution. It was found a good agreement both in terms of general trend and prediction of the exhausting points so thus proving the code to be a reliable tool for an accurate determination of the scraps.

Abstract: In the work, numerical calculations of extrusion process of 2024 alloy through porthole dies were performed. The DEFORM 3D program based on Finite Element Method was used. The way of metal flow, distributions of stresses as well as temperature level within the welding chamber were predicted for different geometry of porthole die. Particularly, different height, width, and shape of the welding chamber were adopted in calculations. The calculations allowed predicting both hydrostatic pressure and temperature levels as well their distributions in the welding region providing the best welding conditions for the alloy tested.

Abstract: Porthole die extrusion has been always more used for the production of hollow profiles. The process is characterized by a complex die whose design is important for the product soundness. The quality of the welding line and, consequently, the quality of the extruded parts strictly depends on the extrusion optimization; for this reason, the influences that, each process parameter has on the pressure along the welding plane, have to be correctly understood. Unfortunately, the complexity of the die geometry generates great research difficulties if different parameters are analyzed; furthermore, even 3D numerical investigations present relevant drawbacks due to the high computational time and the results quality. In this work, a simplified and flexible porthole die is proposed; the equipment was designed and manufactured rectifying a quarter of a traditional porthole die. Moreover, the extruded part has flat shape with welding line in the middle; by doing that, its quality can be simply analyzed through standard tensile tests. Different geometrical variables were investigated, i.e., the bridge shape and width and the bearing length; their interactions on the process dynamics and on the product quality were also discussed. The Analysis of Variance (ANOVA) technique was used to evaluate the obtained results.

Abstract: The design of porthole dies for aluminum extrusion processes is very complex. For the accurate design, fundamental knowledge about material flow is of major importance. To gain these information, numerical methods are increasingly utilized. The accuracy of the simulation results depends mainly on the precision of the used boundary conditions in the model. Therefore, visioplastic analyses of the material flow inside a porthole die are presented in this paper. A special modular tool concept was developed to prepare and visualize the material flow inside the process. The results of the experimental analysis were used for the verification of numerical results which were calculated with the commercial software codes Deform3D and HyperXtrude.