Abstract: A method for manufacturing a golf club head comprising the steps of abutting a joining end surface of a hosel to a joining end surface of a ball-striking member, rotating the hosel while the ball-striking member and the hosel are under pressing contact, thus heating the joining end surfaces of the two members by the heat of friction generated between the joining end surfaces, stopping the rotation of the hosel, and then applying a further, stronger pressure to the joining end surfaces, thus joining them together so as to form the ball-striking member and the hosel into an integral, single unit.

Abstract: A golf club with a ferrule mounted in the opening end of a club shaft insertion hole formed in the hosel of a club head. A plurality of recessed grooves are formed in the inner circumferential surface of the through-hole of the ferrule in which the tip-end of the club shaft is press-fitted, and these recessed grooves are filled and coated with a bonding agent so that the ferrule is securely attached to the tip-end of the club shaft.

Abstract: A metal-wood golf club head having a metallic acoustic adjustment member installed on the inside surface of a sole shell part of the head main body. The acoustic adjustment member is installed so as not to be in contact with the face shell part, crown shell part and peripheral wall shell part that form the head main body.

Abstract: In production of iron golf club from soft-iron material, surface hardening treatment typically such as cementation is applied at least locally to a main body to provide an irregular internal composition made up of a carbonized surface layer and a soft-iron core. Thanks to fortification via surface hardening treatment, a face on the main body can be reduced in wall thickness for reduction in total weight without any substantial degradation in endurance against mechanical shocks at shooting balls.

Abstract: In construction of a metallic wood golf club head having a shell structure made up of a plurality of shell pieces united together, at least one shell piece is at least locally provided with a laminated construction which includes laminated and intermediate layers made of different materials. Changes in combination of materials and allocation of laminated construction allows free adjustment In weight distribution, thereby achieving high ball shooting characteristics and maneuverability at swing. Fortification of the face is made compatible with enlargement in size of a club head.

Abstract: A golf club with one or more annular grooves formed on the outer circumferential surface of the hosel portion of the head, the hosel portion being provided with an outwardly widened tapered surface on the inner circumferential surface of the opening end of a shaft insertion hole of the hosel portion, thus preventing brakeage of the shaft by way of the groove(s) and the tapered surface. The grooves can be filled with non-rigid cosmetic members for a better appearance.

Abstract: A golf club with a head and a hosel which are separate pieces. The hosel connected to the head is made from a material with a low specific gravity and a high strength such as titanium (Ti), a titanium alloy, an aluminum alloy and a fiber-reinforced plastic (FRP), which is different from the material used for the head.

Abstract: In construction of a wood type golf club head, its main body made of a material unsuited for plastic deformation such as FRP and its and hosel made of a material suited for plastic deformation such as metal are separably coupled to each other. Subtle adjustment of ball striking characteristics such as loft and lie angles can be practiced quite freely independently of the material used for the main body.

Abstract: In construction of a shell-type golf club head having a cavity and a hosel shaft hole communicating with the cavity, a mass made of solidified low melting point metal or synthetic resin containing dispersed metallic balls is provided at a selected position within the cavity through infusion via the shaft hole. Supplemental mass addition and weight distribution adjustment can be both carried out very simply without any substantial rise in cost. When located on an internal wall of the cavity contiguous to the club head face, the mass provides enlarged sweet spot on the face.

Abstract: In construction of a golf club in which a shaft is fixed along its lower tip to a main body within a shaft hole formed in a hosel of the main body, an elongated cylindrical core is inserted into the lower tip of the shaft whilst projecting beyond the upper end location of the hosel. Presence of the cylindrical core well fortifies a shaft/hosel joint whilst withstanding impact is generated at shooting balls.

Abstract: In constructioln of a golf club head, presence of a light FRP plate located in a through opening in the face side region allows free weight assignment to other regions for ideal inertia moment adjustment. A metal layer may be provided on the FRP plate to produce a locally laminated face side construction in which thickness ratio of components can be adjusted for better feel at shooting.

Abstract: A method of forming a golf club head by placing an infusion tube with a core in a mold. Sheets of long fibrous material are placed around the core and the mold is closed. Fiber reinforced plastic is forced into the mold and a substantial portion passes through the sheets of long fiber reinforcement and orients the fiber. The material is hardened and the golf club head is removed from the mold.

Abstract: In production of a wood-type golf club head having a rigid shell, metal pieces are dispersed in the matrix of crude foamable synthetic resin filled in the interior of a crude rigid shell for long maintenance in position of the center of gravity of the product despite shocks at shooting balls. The golf club head is formed of a hollow shell having a sole side provided with a first opening. A lid is received within the first opening to form an enclosure. The lid includes a second opening in direct communication with the interior of the hollow shell. The synthetic resin is provided within the interior of the hollow shell through the second opening within the lid. The synthetic resin forms a foam core upon application of heat to the resin.

Abstract: An improved golf club head includes a metallic main body 1 having a face side section 2 providing a face side surface for shooting balls. A rearwardly opening gouge 3 is formed within the main body, extending to an end wall 3a provided by the face side section. An FRP plate 4 is inserted into the gouge and attached to the end wall. Presence of the light FRP plate in the face side region allows free weight assignment to other regions for ideal inertia moment adjustment and produces locally laminated face side construction in which thickness ratio of components can be adjusted for better feel at shooting.

Abstract: A hollow golf club head made from fiber reinforced plastic is provided with a sole plate of composite construction. The sole plate includes an inner resin block interengaged with an outer metal layer. A projection on the resin block extends upward into an opening in the bottom surface of the club head. An aperture passes through the center of the sole plate and through a nut embedded in the resin block. A threaded bolt is screwed into the embedded nut for weight adjustment.

Abstract: An improved golf club head includes a metallic main body 1 having a face side section 2 providing a face side surface for shooting balls. A rearwardly opening gouge 3 is formed within the main body, extending to an end wall 3a provided by the face side section. An FRP plate 4 is inserted into the gouge and held against the end wall 3a by an open frame 5 which engages a circumferential portion of the plate 4. Presence of the light FRP plate in the face side region allows free weight assignment to other regions for ideal inertia moment adjustment and produces locally laminated face side construction in which thickness ratio of components can be adjusted for better feel at shooting.

Abstract: In production of a wood-type golf club head having a rigid shell, metal pieces are dispersed in the matrix of crude foamable synthetic resin filled in the interior of a crude rigid shell for long maintenance in position of the center of gravity of the product despite shocks at shooting balls.

Abstract: In production of a wood-type golf club head having a fiber reinforced shell, a fiber reinforced plastic covering containing long fibers is molded into the shell by application of heat under pressure which enables the shell to fairly assume the complicated configuration of the club head, and use of long fibers assure uniformly oriented reinforcement which results in enhanced elastic impact at hitting balls.

Abstract: A wood-type golf club head includes an additional weight strap embedded, on the sole side, in the section of the fiber reinforced plastic shell preferably in a secured relationship to the sole plate for lower positioning of the center of gravity and firm holding of the sole plate against shock at hitting balls.

Abstract: A fiber reinforced plastic racket frame advantageously usable for a tennis racket has a head portion accompanied with at least an elongated, relatively thin metallic protective member, which has cut-outs or meshes in the construction, formed integral with the outer surface layer of the fiber reinforced plastic envelope at the racket frame. Protection by this additional member assures enriched frictional resistance and reduced collapse of the head portion and presence of the meshes or cut-outs provides firm anchoring of the protective member to the envelope outer surface layer.