Production method and apparatus for filter, forming die for filter, forming assembly for forming filter, and filter

摘要

In a filter production method of the invention, a filter having a shape substantially identical to the shape of a forming surface (31) by extruding semi-molten fibers to the forming surface (31). When the semi-molten fibers are extruded to the forming surface (31), the semi-molten fibers are gathered to upstanding surface portions (31e) of the forming surface (31). Therefore, a sufficient amount of fibers can be layered onto the upstanding surface portions (31e), so that the layering amount of fibers on the upstanding surface portions (31e) of the forming surface (31) will not considerably reduce in comparison with the layering amounts on other portions (31f) of the forming surface (31).