| 摘要 |
PROBLEM TO BE SOLVED: To reduce uncomfortable vibration at the time of hitting a ball and to reduce the weight of a frame in a hollow racket frame. SOLUTION: A mandrel core material 50 is covered with a PTFE tube 16 and a 66 nylon tube 15, a pre-preg 53 formed by impregnating carbon fiber with epoxy resin is fitted to the outer peripheries of the PTFE tube 16 and the 66 nylon tube 15 to form a layered product. Subsequently the layered product 70 is removed from the mandrel core material 50 to be set in a cavity of the metal mold, and with the internal pressure of the PTFE tube 16 increased, the metal mold is heated to form a hardened layer of the fiber reinforced thermosetting resin. After that, one end of the PTFE tube 16 projected into the end opening in the formed frame 80 is held to pull out the PTFE tube 16 from the interior of the frame. |
