Method for attaching water-repellent filter to inlet or outlet of air vent formed in thermoplastic resin molded article, thermally processing tip and thermally welding tip for molding filter attachment portion and for attaching filter, and molded article

A method for installing a filter on an inlet or outlet of a ventilation hole formed on a thermoplastic resin molded article, the method comprising the steps of:

• forming, with a thermal processing tip, a filter installation surface on the inlet or outlet of the ventilation hole formed on the thermoplastic resin molded article;
• providing the thermal processing tip with a construction in which a guiding portion is formed at a center of a top of the main body of the tip, the guiding portion being inserted into the inlet or outlet of the ventilation hole formed on the thermoplastic resin molded article during the step of forming, while a pressing heating surface is formed around the base part of the guiding portion, and a flange is further formed on an outer circumference of the heating pressing surface at a position slightly set back and to form the filter installation surface using the thermal processing tip, the guiding portion is inserted into the inlet or outlet of the ventilation hole on the thermoplastic resin molded article, with the thermal processing tip being heated electrically and pressed to cause the top of the thermal processing tip to sink in the inlet or outlet of the ventilation hole, thereby melting resin around the inlet or outlet of the ventilation hole, and the top is caused to sink until the molten resin comes in contact with the flange, thereby raising a circumference of the inlet or outlet of the ventilation hole to form a filter-fastening rib to receive the filter;
• providing a thermal welding tip, for fastening the filter, with a construction in which a thermal processing rib is jutted out at the center of the top surface of the thermal welding tip, and a gate rib is formed outside the thermal processing rib, thereby forming the pressing heating surface between the thermal processing rib and the gate rib;
• dropping the filter on the filter installation surface formed on the inlet or outlet of the ventilation hole through use of the thermal welding tip, the thermal welding tip is heated electrically and caused to descend so that the pressing heating surface is pressed against the top of the filter-fastening rib while the filter-fastening rib is bent inward in a circular manner along the pressing heating surface and is simultaneously molten, and the molten resin covers the periphery of the filter such that the periphery is wrapped with the resin, while the top of the thermal processing rib causes the filter to bite into the surface of the filter installation surface;
• and then cooling air is blown to cool and harden the molten resin.