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Reasonable design and matching of die structures and process parameters play crucial roles in seam weld quality and variations in extrusion load and exit temperature during magnesium alloy porthole die extrusion. In this study, the arbitrary Lagrangian–Eulerian algorithm was employed to simulate the welding process of metal streams and calculate the peak extrusion load and exit peak temperature. Three-dimensional curved surfaces were applied to investigate the distributions of welding pressure, temperature, effective strain rate and stress on the welding plane, and seam weld quality was quantitatively assessed by the J- welding criterion. Four die structural and five process parameters were used as changeable design variables. Taguchi experiments and the signal-to-noise (S/N) ratio method were utilized to evaluate and optimize these parameters. The significance orders of all parameters to the three formability indexes were obtained by analysis of variance. It was found that for the studied magnesium extrudate, with the increase of welding angle, welding chamber height, bearing length, extrusion ratio and billet temperature, the S/N ratio of welding value decreases rapidly. The S/N ratio of exit peak temperature decreases rapidly as extrusion velocity, extrusion ratio, and billet temperature increase. The S/N ratio of peak extrusion load increase obviously with decreasing bearing length and extrusion ratio, and increasing extrusion velocity, billet, container and porthole die temperatures. The extrusion ratio, welding chamber height, bearing length, and welding angle significantly affect seam weld quality; the extrusion velocity has the greatest effect on exit peak temperature, followed by billet temperature and extrusion ratio, while extrusion ratio, billet, porthole die temperatures, and bearing length play important roles in the variation of peak extrusion load. The optimal combinations of all parameters for the three formability indexes were determined. The extrusion experiment and wedge expansion test verified the accuracy of the optimal parameters for seam weld quality by using the Taguchi method and S/N ratio analysis.

Thermoplastic extrusion, a widely used method for processing thermoplastic materials, requires precise temperature control to ensure product quality. However, existing computer-aided engineering tools often oversimplify the temperature distribution calculations, leading to additional discrepancies between simulations and the actual processes. This study introduces a novel multi-region modeling approach to address this issue. By employing realistic temperature control conditions, the methodology overcomes the limitations of current numerical modeling tools. The key contributions include the development of a transient, incompressible, non-isothermal solver integrated into the OpenFOAM computational library and the implementation of a specialized boundary condition that emulates Proportional-Integral-Derivative (PID) control using real-time thermocouple measurements. The findings highlight temperature deviations at the flow channel walls and total pressure drop while demonstrating a smaller impact on velocity and flow uniformity at the outlet under steady-state conditions. This research substantially advances the understanding of thermal dynamics in extrusion processes, offering crucial insights for enhancing temperature control and laying the groundwork for more effective and precise operational strategies.

Extrusion experiments and 3D numerical modeling were conducted to investigate the dynamic recrystallization and welding quality of a 6063 aluminum alloy hollow square tube extruded by a porthole die at the ram speeds of 3 mm/s, 7 mm/s, 9 mm/s and 11 mm/s. The results showed that average grain size of hollow square tube extruded at the ram speed of 7 mm/s was the smallest. The profile extruded at the ram speed of 3 mm/s exhibited the highest expansion ratio. Dynamic recrystallization (DRX) fractions were highly variable at different ram speeds. DRX fractions in the matrix zones were higher than those in the welding zones, resulting in smaller grain sizes in the matrix zones. Mechanical properties in the welding zones and matrix zones was different. A local strain concentration would occurred during expansion, which would affect the welding quality. Finally, it was found that the uniform microstructure near the welding line would also affect the welding quality.

This work presents a novel fully automated computational framework for optimizing profile extrusion dies, aiming to achieve balanced flow at the die flow channel outlet while minimizing total pressure drop. The framework integrates non-isothermal, non-Newtonian flow modeling in OpenFOAM with a geometry parameterization routine in FreeCAD and a Bayesian optimization algorithm from Scikit-Optimize. A custom solver was developed to account for temperature-dependent viscosity using the Bird–Carreau–Arrhenius model, incorporating viscous dissipation and a novel boundary condition to replicate the thermal regulation used in the experimental process. For optimization, the die flow channel outlet cross-section is discretized into elemental sections, enabling localized flow analysis and establishing a convergence criterion based on the total objective function value. A case study on a tire tread die demonstrates the framework’s ability to iteratively refine internal geometry by adjusting key design parameters, resulting in significant improvements in outlet velocity uniformity and reduced pressure drop. Within the searching space, the results showed an optimal objective function of 0.2001 for the best configuration, compared to 0.7333 for the worst configuration, representing an enhancement of 72.7%. The results validate the effectiveness of the proposed framework in navigating complex design spaces with minimal manual input, offering a robust and generalizable approach to extrusion die optimization. This methodology enhances process efficiency, reduces development time, and improves final product quality, particularly for complex and asymmetric die geometries commonly found in the automotive and tire manufacturing industries.

In the present work, an accurate 3D-FE model for simulating the extrusion process of AZ31 magnesium alloy tube was established based on the DEFORM 3D software package. The metal flow behavior and formation process of weld seam in the porthole die were revealed. The evolutions of temperature, velocity, and effective stress during the whole extrusion cycle were investigated. The K welding criteria was utilized to evaluate the influence of extrusion speed on the seam weld quality. Extrusion experiments were carried out at the extrusion speed ranging from 0.25 to 4 mm/s on an 800-t extrusion press. The simulation results show that the temperature distribution in the workpiece was not homogeneous. As the extrusion process proceeded, the greater the temperature gradient of workpiece was. The maximum temperature appeared at the bearing region. The dead metal zones existed at the corner between the container and the die face and between the bottom and the sidewall of welding chamber. The effective stress near the bearing and welding chamber was maximum, followed by the inlet ports of porthole die, and the minimum value was located in the container. As extrusion speed increased, the temperature, welding pressure, and effective stress on the welding plane increased simultaneously. The calculated K value decreased rapidly when extrusion speed increased from 0.5 to 2 mm/s and then reduced slowly when larger than 2 mm/s. Extrusion speed had a negative influence on the seam weld quality. The criteria exhibited a good predicting capability as compared with the experimental results. The optimum extrusion speed was about 0.5 mm/s for the extrusion of AZ31 magnesium alloy tube at the billet temperature of 400 °C on the 800-t extrusion press.

Currently, the extrusion process with traditional conical die or elliptic die will cause the problems of high energy consumption and stress concentration. In order to address these problems, a novel streamline die characterized by the Gaussian function is designed first. The corresponding velocity field is constructed on the basis of the condition of equal flow per second. By using the newly constructed velocity field, the energy analysis of the extrusion is conducted, and the concrete internal work rate of plastic deformation, shearing work rate, and work rate of friction are obtained by a new method, called the feature-fitting substituting method. Then, the analytical expressions of extrusion force and stress state coefficient are obtained by the upper bound method. Simultaneously, the finite element (FE) simulation is conducted to verify the accuracy of the analytical expression of extrusion force and to disclose the advantages of the present die over the existing dies. The results show that the extrusion forces obtained from the present die match well with the simulation results, and the maximum deviation is no more than 1.73%. Above all, it is proved that the present Gaussian die can consume less energy and reduce the possibility of die loss evidently.

Extrusion process has excellent capability in continuous manufactures with high production volume, low cost, and steady quality for very complex cross-sectional products. However, manufacturing a proper extrusion die is challenging, but essential for qualified products, which needs to consider many influence factors in the die design. This paper shows an improved inverse design method for thin-wall hollow profiled polymer extrusion die by using computational fluid dynamics simulation. Also, the design criteria of the inverse design method for extrusion die are proposed and discussed. The simulation results show that the thickness of the die lip gap can be enlarged with the decreasing of the inlet flow rate. Additionally, it shows that the geometry profile of the die lip gap can be widened with the increasing of the length of the free jet. The analytical results have been verified by experiments and show a good agreement. It is concluded that the improved inverse design method with FEM-CFD simulations can provide better accuracy and significantly reduce the manufacturing difficulty of micro and thin-walled extrusion die.

Biodegradable polymers are promising materials for films and sheets used in many widely diffused applications like packaging, personal care products and sanitary products, where the synergy of high biocompatibility and reduced environmental impact can be particularly significant. Plasticized poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) blend-based films, showing high cytocompatibility and improved flexibility than pure PLA, were prepared by laboratory extrusion and their processability was controlled by the use of a few percent of a commercial melt strength enhancer, based on acrylic copolymers and micro-calcium carbonate. The melt strength enhancer was also found effective in reducing the crystallinity of the films. The process was upscaled by producing flat die extruded films in which elongation at break and tear resistance were improved than pure PLA. The in vitro biocompatibility, investigated through the contact of flat die extruded films with cells, namely, keratinocytes and mesenchymal stromal cells, resulted improved with respect to low density polyethylene (LDPE). Moreover, the PLA-based materials were able to affect immunomodulatory behavior of cells and showed a slight indirect anti-microbial effect. These properties could be exploited in several applications, where the contact with skin and body is relevant.

The structure of the extrusion die has great influence on material flow balance and product quality for large-size aluminum alloy profiles, especially the pre-allocated structure, such as spread die and flat container. In this work, regarding the practical problems existing in practical production of a large-size, hollow, and flat-wide aluminum alloy profile used in the high-speed train, the porthole extrusion process with cylinder container and spread die is firstly simulated using HyperXtrude and verified experimentally. The spread die is then optimized by combining the design of experiments with response surface method. With the optimized spread die, the maximum velocity difference in the cross section of the profile reduces from 8.63 to 3.07 mm/s, and the corresponding SDV reduces from 1.56 to 0.69 mm/s. Finally, the different structures of containers are designed; the effects of cylinder container and flat containers with different transition form on material flow, billet skin, and die stress in numerical simulation process are comparatively analyzed; and the design rules of extrusion dies are summarized for large-size, hollow, and flat-wide aluminum alloy profiles. By comparison, the maximum velocity difference decreases from 14.41 to 3 mm/s, and the maximum stress on the extrusion dies decreases from 999 to 670 MPa, and the dead zone also greatly decreases in flat container extrusion.

Coat-hanger dies are widely used in the extrusion of polymer sheets and films. However, when designing the flat film/sheet extrusion dies manufacturing companies still facing difficulties in achieving the flow uniformity of the polymer melt. This affects the product quality and tool life. This study examines the existing extrusion die design which is used in in the industry in Kazakhstan for polypropylene sheet production and proposes better geometry of a die. These die geometries will be tested for flow uniformity in terms of velocity and pressure at the outlet.