ABSTRACT
The section of the profile is provided with a hollow part and a typical semi-hollow part, the area of the section is 291 mm2, and the maximum tongue ratio of the semi-hollow part is 6.5.
Compared with the determination principle of the semi-hollow section, the ratio of the tongue is more than the maximum value allowed in the opening, and so the part can be determined as a semi-hollow section. In practice, if the die structure is still an ordinary structure, then the strength of the cantilever in the extrusion process is very dangerous and prone to fracture, thereby resulting in premature failure of the die. Therefore, this section should be ruled as a semihollow section with a hollow part. For single-cavity dies, in order to solve the strength of the cantilever in semi-hollow profile extrusions, more structures are usually used in a cutting type porthole die, and its cantilever is cut into two parts, and one part is separated as the core of the male die. In the die with single
1 INTRODUCTION
The porthole extrusion die with four cavities, in particular for the semi-hollow section, is a multi-cavity die extrusion technology. It is designed particularly for semi-hollow profiles, with four cavities in a die, where four identical profiles will be extruded synchronously at a time. It is a good method to rely on technological innovation to cope with the continued rise of cost of human resources and energy costs and the lack of land supply. Especially in an extrusion machine equipped with a trend of large scale, it can solve the problem since a small machine has too many orders to complete, and a large machine has not enough orders to work on. In the extrusion of multi-cavities, the die is the key. Research on this technology exhibits an ascending trend in our country; especially in recent years, the majority of experts, scholars, and engineering and technical personnel carry out lot of research and exploration. Through an actual case, a new kind of four cavities protection type structure will be introduced, which is specially designed for the semihollow section, as a reference to designers.
