Manufacturing technology of hollow section

Extrusion process for producing profiles. The extruded profiles are divided into two categories: hollow section and solid section. Hollow section refer to profiles with one or more closed through-holes. There are more than 30 thousand kinds and specifications of extruded profiles, especially aluminum profiles, up to 2.4 or more. Followed by copper profiles, magnesium profiles and hollow section and plastic profiles. Solid extrusion profiles accounted for about 65% of all extrusion profiles, while special section profiles accounted for the majority of ASTM A36 Square Hollow Section, followed by hollow extrusion profiles, such as aluminum doors and hollow section, plastic doors and windows profiles. Compared with other methods such as rolling and die forging, the strength of extruded profiles is higher. The replacement of hollow section is relatively simple and can be produced in small quantities. Using extrusion method to produce complex shape products, especially those with large cross-section changes, can greatly reduce the amount of mechanical processing, reduce metal losses, and improve the performance of parts and structures.

　　The hollow section mainly adopts forward extrusion, backward extrusion and combined extrusion. Combined extrusion is not widely used at present. Hollow section can be based on the shape of hollow profile, the number of holes, the degree of asymmetric distribution of holes to the center of profile section, and other factors, using piercing pin method and welding extrusion method. The former uses hollow section or solid billet for forward extrusion or reverse extrusion; the latter is suitable for forward extrusion of metals and alloys with good weldability, especially when extruding aluminium alloy building profiles.