US Patent 7305792 Tip rod

Where a super-elastic alloy is used as a core material, boundary separation can be prevented on substantial deflection. The super-elastic alloy is used as the core material, an outside layer made with fiber-reinforced resin is provided outside except the tip part region of the core material, and a resin-rich layer greater in resin ratio than the outside layer is provided between the outside layer and the core material so as to be adjacent to the core material.