Abstract: An injection molding system for molding a hollow plastic article employs a hollow mold core having a longitudinal axis and a core runner cavity that has a uniform cross section throughout and which extends to the open end of the mold core. The mold core includes at least one core ejection gate and at least one core inlet gate leading from the outer surface of the core wall to the core runner cavity. When molding is performed in stages, there is it least one core ejection gate for each stage of molding. The core is clamped in between separate sets of molding blocks for each stage of molding. A core end closure cap having a core extension cavity aligned with the core runner cavity is used to close the open end of the mold core. A molten plastic is injected into the outer molding blocks and is confined to travel through the core inlet gate of the core without entering the mold cavity directly so that the molten plastic is forced to pass through the core runner cavity in order to reach the core ejection gates.

Abstract: An injection molding system for molding a hollow plastic article employs a hollow mold core having a longitudinal axis and a core runner cavity that has a uniform cross section throughout and which extends to the open end of the mold core. The mold core includes at least one core ejection gate and at least one core inlet gate leading from the outer surface of the core wall to the core runner cavity. When molding is performed in stages, there is it least one core ejection gate for each stage of molding. The core is clamped in between separate sets of molding blocks for each stage of molding. A core end closure cap having a core extension cavity aligned with the core runner cavity is used to close the open end of the mold core. A molten plastic is injected into the outer molding blocks and is confined to travel through the core inlet gate of the core without entering the mold cavity directly so that the molten plastic is forced to pass through the core runner cavity in order to reach the core ejection gates.

Abstract: A golf club grip is formed of a hollow, inner socket and an outer jacket produced from different charges of thermoplastic rubber. The socket and jacket differ in stiffness characteristics, colors, or both stiffness and color. The outer jacket is molded onto the socket and bonded thereto throughout the surfaces of contact therebetween. The torsional stress on the jacket is transmitted to and resisted by the inner socket through the bonding that occurs throughout the interface between the jacket and the socket. Preferably, the socket has an inner socket core portion with a plurality of radially projecting protrusions. The structure of the jacket laterally surrounds the protrusions so that the outermost surfaces of the protrusions are exposed. The golf club grip is produced from a pair of identical mounting cores which are rotated between a pair of molding dies.