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

摘要

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