Patent Application
20080064538
The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. In the drawings:
When assembled the two-piece bat comprising the barrel and handle has an overlapping junction region where the taper sections engage one another. The taper sections are sized to provide an interference fit between the handle and barrel. That is, at least a portion of taper section 24 nearest joint end 26, and at least a portion of taper section 30 nearest joint end 28 overlap one another and form junction region J. The dashed vertical line in
The two-piece bat comprising the barrel and handle are assembled as shown schematically in
An alternative embodiment bat 10′ of the present invention employs a mixture of glass shafting beads in the rigid adhesive compound. The junction area labeled J′ in
The mixture of glass shafting beads and rigid adhesive ensures self-alignment of the barrel and handle, and even distribution of the adhesive throughout the junction. As employed in the manufacture of golf clubs, the glass shafting beads help to self-center and align the joint, and ensure that the adhesive is evenly distributed over the joining surfaces and that the joining surfaces are separated from one another by a specific and consistent distance as determined by the diameter of the glass beads. Glass shafting beads are available in multiple sizes, mostly very fine such as 0.002 inch to 0.020 inch in diameter. The preferred range of sizes for the present invention is between 0.005 inch and 0.010 inch in diameter.
The use of rigid adhesive in the present invention, with or without glass shafting beads, provides a rigid connection that does not damp energy, but rather maximizes the stiffness and liveliness of the joint. For the rigid adhesive, the preferred compounds are epoxy or acrylic based rigid glues. In contrast, elastomer compounds which have been used in ball bat construction serve an isolation function. That is, they are designed to absorb and dissipate energy, not store and return it. The rigid connection of the present invention enhances performance by ensuring that energy from the impact of the ball is returned to the ball instead of dissipated in the bat. The ball bat of the present invention relies on inherent vibration damping characteristics of the composite material of the handle, and the engineering of that handle to reduce sting to the player's hands when the ball is hit. As the vibration wave travels down the barrel and into the handle, the composite handle damps vibration along its entire length to provide comfort to a player's hands. This is a particularly effective approach given that the ball to bat collision is so brief and instantaneous. This collision is largely a local event and occurs so quickly that before the vibration or sting reaches a player's hands, the ball has been hit. The composite handle enables the damping to occur closer to the player's hands so that any damping action takes place after the bat as returned the maximum amount of collision energy to the ball and the ball is no longer in contact with the bat.
The barrel of the present invention is preferably made of an aluminum alloy for durability and strength. It is also possible that a resin with carbon and/or glass fiber composite could be engineered to have similar durability, strength and hardness characteristics as a metal barrel. Such an engineered material for the barrel is within the purview of the present invention, and in this application is referred to as being metal-like. The handle is preferably a composite of curable resin impregnated with carbon and glass fibers which is amenable to tuning and engineering for desired performance characteristics. This engineering is simply a way to tune the conversion of potential energy into kinetic energy when a ball is hit. Potential energy is stored when the ball and bat undergo a physical deformation at collision. That energy is converted to kinetic energy as the ball and bat return to their respective original shapes and the stored energy is released into the energy of the ball's movement away from the bat. With prior art wooden bats, the ball undergoes more deformation upon impact. With an aluminum or composite barrel, the bat is able to store and release a portion of the potential energy of impact. The composite handle enables the bat designer to change the degree of flexibility in the handle portion to maximize bat speed and strength. A handle portion with optimized flexibility based on the swing speed of the player will enable the bat to return more of the energy of the player's swing to the ball by strong swing energy in the form of handle flex and releasing it by straightening at the moment of impact. Depending on the strength of the player, it may be better to stiffen or increase the flexibility of the handle, and composite enables that type of tuning.
The ball bat of the present invention having a rigid connection between the barrel and handle employing a combination of mechanical interference and a rigid adhesive that prevents direct contact between the barrel and handle results in enhanced performance with reduced complexity and cost of manufacture. Eliminating direct contact between the barrel and handle at the junction eliminates the need to provide any mating features which also eliminates costly manufacturing steps and enables assembly to be greatly simplified. The composite handle provides opportunities to engineer the bat for optimum performance without sacrificing the durability and strength of a metal or metal-like barrel. Interposing a layer of rigid adhesive between the barrel and handle results in a rigid joint that maximizes the distance the ball will travel by ensuring that as much energy from the impact is returned to the ball.
While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that may more embodiments and implementations are possible that are within the scope of the invention.
