# Effects of Solid Die Types in Complex and Large-Scale Aluminum Profile Extrusion
###### 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 deformation were used to assess the advantages and disadvantages of the dies. Transient simulations were performed to analyze the evolution of transverse weld in the pocket and spread dies. The effects of ram speeds on the related extrusion parameters were also investigated. The research results provide useful guides for designers and engineers in selecting these types of extrusion dies. s 2020 26 December 2019 29 December 2019 29 December 2019 2020 2019 2020 2  
parameters of extrusion process can be obtained such as extrusion velocity, product temperature, die deformation, die stress, welding seam etc. [10; 11; 12]. There are many parameters involved in the die design. Among them, the parameters of bearing length were considered by many designers [2; 13; 14]. Using variable bearing length is one of the traditional methods for adjusting the balance of material flow [2; 14]. The adjustment results usually rely on the experience of the engineer because of the complexity of the natural flow in the die. Several studies have introduced the methods for determining the appropriate bearing length. [PERSON] et al. [13] proposed some standards and rules for the bearing length calculation based on their practical experiences. [PERSON] et al. [15] used the numerical simulations to formulate an equation of bearing length in flat die hot extrusion. The bearing length equation is a function of the cross-sectional thickness and distance from the die center. The relationship between minimum bearing length and flow pressure was studied by [PERSON] [16]. [PERSON] et al. [17] proposed a method for calculating bearing lengths of simple solid geometry using numerical simulations. This method was verified by extrusion experiments for traditional flat-face die. In general, the calculation of bearing length is relatively complicated and time-consuming, especially in the case of complex cross-sectional profiles [16; 18]. Besides the bearing length, the design of solid extrusion dies also concerns with the geometries of the entrance and the pocket [14]. The pocket extrusion die provides the pressure needed for charge weld [2; 14]. On the other hand, using the pocket in front of the die exit is an effective solution for controlling the distribution of the velocity of metal flow in the die [2; 14; 19; 20]. The pocket geometry can be designed with single or multiple steps. Multiple cavity pocket is more advantage compared to single cavity one [21]. The design of the pocket has been considered by many authors. [PERSON], [PERSON] et al. [22] investigated the effect of the angle and volume of the cavity on metal flow in the pocket extrusion die using 2D finite element (FE) analysis. They showed that adjusting the pocket angle is an effective solution to balance the flow. [PERSON], [PERSON] et al. [23] revealed the effect of the entrance geometry and the pocket structure on flow in the solid die using simulation. They pointed out that using multiple steps can reduce the volume of the dead-metal zone, and the entrance geometry of the pocket can be used to eliminate the concave effect formed on the flat surface of a profile after extrusion. [PERSON] et al. [21] studied the influence of pockets in the two-cavity die extrusion employing three-dimensional (3D) FE simulations. They showed that the designed die with multi-step pockets can reduce extrusion pressure and distribute the flow more evenly. [PERSON] et al. [24] studied the optimal pockets' geometry of solid die for H-shaped aluminum profiles.