Joint making method for sheet metal, involves providing sheet metal with thickness lesser than preset percent of nominal thread diameter of flange or thread screw, and forming flange by forming die using extrusion press

摘要

The method involves providing a sheet metal with a sheet metal thickness (14) lesser than 25 percent of the nominal thread diameter of a sheet metal flange or a thread screw. The sheet metal flange is formed by a forming die (18) using an extrusion press. The sheet metal flange is exclusively formed using a forming punch (20) by an extrusion press forming process or a superimposed irregular and extrusion press forming process. A forced flow movement of a sheet metal flange material occurs in a forming movement direction of the forming punch.