Patent ID: 7427331

Claim:
A method for manufacturing a composite product by welding a first resin part to a second resin part with a laser beam, the method comprising: preparing the first resin part and the second resin part, the first resin part having an opening of which inner diameter continuously decreases at a first angle in an axial direction thereof, the second resin part having a changing part of which outer diameter decreases at a second angle in the axial direction, the first angle and the second angle having a different value respectively from each other; inserting the changing part of the second resin part into the opening of the first resin part; pressing an outer surface of the second resin part to an inner surface of the opening of the first resin part; and radiating the laser beam to the contacting area between the outer surface of second resin part and the inner surface of first resin part, while pressing the outer surface to the inner surface, whereby the second resin part moves in the pressing direction, wherein the second resin part is prepared in such a manner that a smallest outer diameter of the changing part at its end is larger than a smallest inner diameter of the opening at its end, the end of the changing part having the smallest diameter is pressed into the inner surface of the opening while the laser beam is radiated, and the first resin part is prepared in such a manner that the opening is tapered; and the second resin part is prepared in such a manner that the changing part has a taper angle which is smaller than a taper angle of the opening.