| 摘要 |
PROBLEM TO BE SOLVED: To lessen an unpleasant oscillation at shooting and the weight of a frame in a midair racket frame. SOLUTION: A mandrel core material 50 is covered with a PTFE tube 16 and a nylon tube 66. A lamination layer body 70 is formed by placing pre-preg 53 which is obtained by impregnating a carbon fiber with an epoxy resin on the periphery of the PTFE tube 16 and the nylon tube 66. This lamination layer body 70 is removed from the mandrel core material 50 and is set in a cavity of a metal mold M. Under the conditions of increasing an inner pressure of the PTFE tube 16, a hardened layer 17 of a thermosetting resin whose fibers are enhanced is formed by heating the metal mold M. After that, the PTFE tube 16 which sticks out of an end opening part 80a of the formed frame 80 is extracted from the frame 80 by pulling the stick out end of the PTFE tube 16. |
