Abstract:Increasing customer requirements for quality and productivity in extruding aluminum products has led to the development of different types of extrusion dies. In this study, three different types of dies, including traditional flat die, pocket die and spread die were designed to extrude complex and large-scale solid profiles. The design parameters for these dies were used from actual extrusion experience. The results obtained from steady-state simulation such as velocity, temperature, extrusion force, and die d… Show more
“…Here, the curving behavior was found when the grain size approached the billet size. Crystal plasticity finite element (CPFE) simulations were conducted to demonstrate that the grain orientations played an important role [34]. Although both grain sizes and grain orientations were found to affect the deformation behaviors, it was still unclear what the mechanism was that drove the micro-extrusion part to curve and how the curving direction was dictated.…”
The precision and accuracy of the final geometry in micro-parts is crucial, particularly for high-value-added metallic products. Micro-extrusion is one of the most promising processes for delivering high-precision micro-parts. The curving tendency observed in micro-extrusion parts is a major concern, significantly affecting the final part geometry. The purpose of this paper was to investigate the driving mechanism behind the curvature in micro-extrusion at room temperature. A finite element (FE) simulation was carried out to observe the influential primary factors: (1) grain size, (2) grain boundary, (3) grain orientation, and (4) bearing length of a 6063 aluminum alloy. The Extrusion Curvature Index (ECI) was also established to indicate the level of curvature in micro-extruded parts. The results showed that the grain boundary at the high strain and die opening area was the dominant factor for single-grain conditions. The interactive effects of the grain boundary and grain orientation also affected the curvature under single-grain conditions. If the number of grains across the specimen increased up to 2.7 (poly-grains), the curvature effect was dramatically reduced (the pins were straightened). For all conditions, the curvature in micro-extrusion could be eliminated by extending the bearing length up to the exit diameter length.
“…Here, the curving behavior was found when the grain size approached the billet size. Crystal plasticity finite element (CPFE) simulations were conducted to demonstrate that the grain orientations played an important role [34]. Although both grain sizes and grain orientations were found to affect the deformation behaviors, it was still unclear what the mechanism was that drove the micro-extrusion part to curve and how the curving direction was dictated.…”
The precision and accuracy of the final geometry in micro-parts is crucial, particularly for high-value-added metallic products. Micro-extrusion is one of the most promising processes for delivering high-precision micro-parts. The curving tendency observed in micro-extrusion parts is a major concern, significantly affecting the final part geometry. The purpose of this paper was to investigate the driving mechanism behind the curvature in micro-extrusion at room temperature. A finite element (FE) simulation was carried out to observe the influential primary factors: (1) grain size, (2) grain boundary, (3) grain orientation, and (4) bearing length of a 6063 aluminum alloy. The Extrusion Curvature Index (ECI) was also established to indicate the level of curvature in micro-extruded parts. The results showed that the grain boundary at the high strain and die opening area was the dominant factor for single-grain conditions. The interactive effects of the grain boundary and grain orientation also affected the curvature under single-grain conditions. If the number of grains across the specimen increased up to 2.7 (poly-grains), the curvature effect was dramatically reduced (the pins were straightened). For all conditions, the curvature in micro-extrusion could be eliminated by extending the bearing length up to the exit diameter length.
“…4. The bearing length at the tip of the extrudate is approximated as 0.6 times the adjacent bearing length [19]. It is noted that the upper die does not contain a mandrel as the traditional hollow dies.…”
Section: Geometry Of the Aluminum Heatsink And Initial Die Structurementioning
confidence: 99%
“…• ε is the effective strain rate; Q, R, and T are the activation energy, gas coefficient, and absolute temperature, respectively. The parameters of AA6063 material used in Equation ( 1) are as follows [19]: β = 4 × 10 −8 m 2 /N; Q = 1.4155 × 10 5 J/mol; R = 8.314 J/(mol . K); A = 5.90152 × 10 9 s −1 ; n = 5.385.…”
Section: Construction Of Finite Element Modelmentioning
confidence: 99%
“…The bearing length at the tip of the extrudate is approximated as 0.6 times the adjacent bearing length [19].…”
In this study, porthole die used for extrusion of a solid heatsink profile with wall thickness variation ratio up to 15.3 was designed using finite element (FE) simulations. To improve the flow balance in the die, a design approach was introduced to find the appropriate die structure, which includes the porthole and pocket geometry correction, the bearing length adjustment, and the port bridge structure modification. Using the proposed die, the predicted velocity relative difference (VRD) and the maximum velocity difference (ΔV) of extrudate were significantly lower than those of an initial die, which was preliminarily designed based on general design experiences. The required extrusion force and the residual stress in the product were also reduced significantly. Then, the effects of the port bridge structure and welding chamber height on the behavior of the metal flow in the die were investigated. To verify the proposed die design, experimental extrusions were conducted on a 930-ton extruder. The experiment results showed that the extruded product fulfilled the requirements for dimensional tolerances. The design approach presented in this paper can be useful for practical implementation of die design when extruding similar solid heatsink profiles with large wall thickness variation.
“…A technological variant possible to apply for obtaining welded constructions as safe as possible is represented by the application of the welding technique "temper bead welding" (TBW) which consists in depositing one or more welding rows on a certain surface or on another weld, in order to improve the metallurgical properties of the heat affected zone (HAZ) or to the previously deposited layer. The TBW technique is mainly applied to steels that can show cracking in the area of thermomechanical influence or to those that can develop cracking on reheating [8,9].…”
Welded constructions are subject to high stresses during operation. One solution for improving the behavior in exploitation of welded constructions in various cases is to use the welding technique “temper bead welding” (TBW). In the paper, the optimization of the geometry of the welded joints by the TBW technique was performed. Thus, corner welded joints made of S355 steel were analyzed. To make the welded joints, three layers of welding seams were deposited, and the intermediate layers were processed through cutting with various radii. To analyze the influence of the size of these rays on the behavior of welded constructions, a research program based on factorial experiences was designed. The samples were tested in terms of fatigue behavior by applying loads between ±8 kN and ±12 kN. The research also focused on determining the hardness of the materials in the joints welded and on determining the microstructure of the materials in the heat affected zone (HAZ). Research has shown that it is possible to improve the characteristics of joints made by the TBW technique in the sense that it can be achieved an improvement in fatigue stress, a decrease in the hardness of the HAZ material and an improvement in the metallographic structure of the HAZ material, meaning that it has a structure made of ferrite and fine pearlite.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.