Badminton racket and manufacturing method of badminton racket

A badminton racket manufacturing method comprising:

• a resin sheet tube forming process that forms a resin sheet tube by placing an expandable resin that expands when heated on an inner side of a thermoplastic resin sheet and rolling the thermoplastic resin sheet into a cylindrical shape;
• an expandable resin placing process that places an expandable resin that expands when heated on an outer periphery of a portion of a joint,
• the joint being to be installed to reach
• inside a frame formed with the resin sheet tube and
• inside a shaft,
• the portion being to be installed in the frame;
• and
• a joining process that joins the frame and the shaft by
• installing the joint placed with the expandable resin inside
• both end portions of the resin sheet tube, bent circularly and butted against each other, and
• the shaft, and
• setting the frame, the shaft and the joint in a die, and then heating the frame, the shaft and the joint, and spreading out the both end portions along the die by the expandable resin placed on the joint,
• wherein
• in the joining process,
• a pushing of the resin sheet tube against the die with the expandable resin in the resin sheet tube, and
• a pushing of the both end portions of the resin sheet tube against the die with the expandable resin on the joint
• are performed substantially simultaneously.