Hybrid golf club shaft

Abstract

A hollow golf club shaft of circular cross-section comprises a tubular core layer, a tubular outer layer, and a tubular intermediate member juxtaposed to both the core layer and the outer layer, wherein the core layer and the outer layer coextend substantially the entire length of the shaft.

1 . A golf club shaft comprising a core layer, an intermediate layer about the core layer, and an outer cover layer about the intermediate layer, wherein the intermediate layer comprises metallic fibers, filaments, wires, strips, or ribbons; the outer cover layer is a non-porous metal sheath; and at least two of the three layers coextend the shaft's entire length.  
   
   
       2 . The shaft of  claim 1 , wherein the outer cover layer comprises titanium, steel, stainless steel, aluminum, tungsten, nickel, copper, zinc, chromium, brass, bronze, magnesium, tin, gold, silver, alloys thereof, or metallic matrix composites.  
   
   
       3 . The shaft of  claim 1 , wherein the outer cover layer consists essentially of metal fibers or filaments.  
   
   
       4 . The shaft of  claim 3 , wherein the metal fibers or filaments are stainless steel or titanium.  
   
   
       5 . The shaft of  claim 1 , wherein the outer cover layer comprises at least one ferrous metal and at least one non-ferrous metal.  
   
   
       6 . The shaft of  claim 1 , wherein the intermediate layer comprises titanium, steel, stainless steel, aluminum, tungsten, nickel, copper, zinc, chromium, brass, bronze, magnesium, tin, gold, silver, alloys thereof, or metallic matrix composites.  
   
   
       7 . The shaft of  claim 1 , wherein the intermediate layer comprises at least one ferrous metal and at least one non-ferrous metal.  
   
   
       8 . The shaft of  claim 1 , wherein the intermediate layer further comprises at least one reinforcement material in the forms of particles, flakes, whiskers, continuous or discontinuous fibers, filaments, ribbons, sheets, or mixtures thereof.  
   
   
       9 . The shaft of  claim 8 , wherein the reinforcement material is chosen from boron fibers, ceramic fibers or whiskers, metal-coated fibers, ceramic-coated fibers, diamond-coated fibers, carbon nanotubes, aramid fibers, extended-chain polyethylenes, poly-p-phenylenebenzobisoxazole fibers, polythenes, polyarylates, polyacetals, liquid crystalline polymers, aromatic polyesters, polyallylates, or combinations thereof.  
   
   
       10 . The shaft of  claim 1 , wherein the intermediate layer further comprises at least one non-isotropic reinforcement fiber meshed or interleaved with the metallic fibers.  
   
   
       11 . The shaft of  claim 1 , wherein the intermediate layer comprises a grid, mesh, woven member, braided member, or lattice network member comprising the metallic fibers, filaments, wires, strips, or ribbons.  
   
   
       12 . The shaft of  claim 11 , wherein the grid, mesh, woven member, braided member, or lattice network member is porous.  
   
   
       13 . The shaft of  claim 1 , wherein the intermediate layer adjoins at least one of, or both, the core layer and the outer cover layer.  
   
   
       14 . The shaft of  claim 1 , wherein the intermediate layer further comprises a viscoelastic material.  
   
   
       15 . The shaft of  claim 14 , wherein the viscoelastic material has a strain energy ratio of at least about 2%.  
   
   
       16 . The shaft of  claim 14 , wherein the viscoelastic material has a storage modulus of at least about 10 psi.  
   
   
       17 . The shaft of  claim 14 , wherein the viscoelastic material comprises vinyl copolymers; polyvinyl acetate or copolymers thereof; acrylics; polyesters; polyurethanes; polyethers; polyamides; polybutadienes; polystyrenes; polyisoprenes; polyethylenes; polyolefins; polyvinyl butyral; styrene/isoprene block copolymers; metallized polyesters; metallized acrylics; epoxy-acrylate interpenetrating networks; natural or synthetic rubbers; silicon rubbers; nitrile rubbers; butyl rubbers; styrene-butadiene copolymers; piezoelectric ceramics; thermosetting or thermoplastic rubbers; foamed polymers; ionomers; bitumen; air bladders; liquid bladders; low-density granular materials; or mixtures thereof.  
   
   
       18 . The shaft of  claim 17 , wherein the low-density granular materials comprise perlite; vermiculite; polyethylene beads; glass microspheres; expanded polystyrene; nylon flock; ceramics; polymeric elastomers; rubbers; dendritic particles; or mixtures thereof.  
   
   
       19 . The shaft of  claim 14 , wherein the viscoelastic material expands about 25% to about 100% of the shaft's entire length.  
   
   
       20 . The shaft of  claim 1 , wherein the outer cover layer has a thickness of about 0.02 inches to about 0.05 inches.  
   
   
       21 . A golf club shaft comprising a core layer, an intermediate layer about the core layer, and an outer cover layer about the intermediate layer, wherein the intermediate layer comprises metallic fibers, filaments, wires, strips, or ribbons; the outer cover layer is a non-porous sheath of a material having a Young's modulus of about 5 Mpsi or greater; and at least two of the three layers coextend the shaft's entire length.