ABSTRACT
The semi-hollow sections of the flow guide protection type die structures are formed, that is, for some of the profile sections with a length to width ratio of more than three of the narrow and long sections, according to the structural characteristics of the profile. The porthole bridges are used to cover and protect the cantilever, and there is a certain stress space between the bridge and cantilever. In the extrusion process, even if the porthole bridge bends downward flexibly under force, it would not touch the cantilever instead of bearing the force, and the cantilever will not bear the extruded metal’s positive pressure. In the die, the cantilever can be considered as a cantilever beam, and the bridge is a simple supported beam under a uniform load and the strength of the simple supported beam is greatly improved under the same loading conditions. Obviously, the change or shift of the force conditions can improve the strength of the mold. And so, as long as the bridge has sufficient strength, the strength of the cantilever will be ensured. At the same time, as the cantilever beam, this bending moment that the end of the beam exerts on the root is the biggest, and so in order to improve the stress state and metal supply of the
1 INTRODUCTION
Semi-hollow Al-profiles are quite common in the production of aluminum profiles extrusion dies. The key to the production of a semi-hollow section is the die. The die design of semi-hollow profiles is more difficult and complicated, and the main problem to be solved is the strength of the die. In order to solve the problem, domestic and foreign scholars, experts and engineering and technical personnel have carried out a wide range of exploration and research. In addition to the study of mold materials and heat treatment, more studies are required to explore the die structure, by changing the die structure and changing the stress condition of the cantilever to improve the die strength. This way is particularly effective. In recent years, with the rise of land, labor and energy costs, the overall cost of enterprises rose significantly. In such an economic environment, it is not realistic for enterprises to depend on increasing the number of equipment, the expansion of the plant or to human-intensive and other traditional investments to expand the production scale. The best way to improve productivity and reduce costs is to rely on technological innovation and the use of innovative ways to drive. The extrusion technology of multi-cavities in a die is one of the best ways and methods. The key factor in this extrusion technology is the die, especially for a wide variety of semi-hollow sections, because this type of material usually forms a relatively small section. Therefore, it is more practical to use a model of multi-cavities extrusion. Through an actual example, a new structure named protection type of flow-guided porthole with twin cavities in
cantilever end, the guide grooves must be set in the place of the corresponding bridge, and the end of the cantilever is completely under the protection of the bridge; through the bridge, the metal will perform welding and diversion actions into the sites, thereby reducing the extrusion force of the end, so as to improve the strength of the cantilever.
