Belt molding manufacturing method

A belt molding manufacturing method which is a method for manufacturing a belt molding configured to be attached along an upper edge of a door panel of a door for a vehicle, the belt molding comprising a molding body extending in a longitudinal direction and an end cap attached to one end portion of the molding body in the longitudinal direction, at least one of the molding body and the end cap being made of a thermoplastic resin, the method comprising:

• preparing the molding body, the molding body comprising a vehicle exterior side wall portion, a vehicle interior side wall portion facing the vehicle exterior side wall portion, and a top wall portion integrally connecting the vehicle exterior side wall portion and the vehicle interior side wall portion, the molding body having an opening end in the longitudinal direction;
• preparing the end cap, the end cap comprising a lid portion configured to close the opening end of the molding body, and an insertion portion extending from the lid portion and configured to be inserted between the vehicle exterior side wall portion of the molding body and the vehicle interior side wall portion of the molding body;
• inserting the insertion portion of the end cap into the molding body such that the insertion portion of the end cap is disposed to face a facing portion of the molding body, the facing portion being a part of the molding body;
• performing an ultrasonic vibration pressing, the ultrasonic vibration pressing comprising pressing an ultrasonic horn in an ultrasonic vibration state against at least one of the facing portion of the molding body and the insertion portion of the end cap, and pushing the ultrasonic horn from a vehicle interior side toward a vehicle exterior side, such that a pressed portion pressed by the ultrasonic horn is melted and deformed to form a hole portion recessed on a pressing surface of the pressed portion and a protruding portion protruding on a surface opposite to the pressing surface;
• performing a non-vibration pressing, the non-vibration pressing comprising stopping an ultrasonic vibration of the ultrasonic horn and further moving the ultrasonic horn in a vibration stopped state from the vehicle interior side toward the vehicle exterior side at the pressed portion;
• and
• removing the ultrasonic horn from the pressed portion.