Games using tangible projectile – Projectile – per se; part thereof or accessory therefor – Having solid core within outer cover; core or cover therefor
Reexamination Certificate
2000-09-28
2004-04-13
Wong, Steven (Department: 3711)
Games using tangible projectile
Projectile, per se; part thereof or accessory therefor
Having solid core within outer cover; core or cover therefor
Reexamination Certificate
active
06719653
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to game balls and more particularly is directed to game balls having a hollow central core for use in playing baseball and softball.
BACKGROUND OF THE INVENTION
Professional and competitive play game balls such as baseballs and softballs are traditionally constructed with a solid, spherical central core formed of cork, kapok, or other similar material, surrounded by windings of thread or yarn, and covered with a stitched-on leather cover. These traditionally constructed game balls typically possess excellent play characteristics, particularly when they are new. However, they are also relatively expensive and thus are rarely used outside high levels of game play.
In spite of the expense and the care that goes into manufacturing, balls having a traditional construction often have a very limited playing life. Striking a ball with a bat in the normal course of play often causes the surface of the ball to become flattened at the point of impact, or to otherwise depart from its original spherical shape. Forces from the impact between the ball and bat also travel through the ball and contribute to the breakdown and destruction of the central core. A ball with traditional construction that receives repeated bat impacts may loose much of its liveliness as the central core deteriorates. Therefore, baseballs of traditional construction are often removed from play in professional and high level competitive play after relatively little use.
An additional problem associated with balls having a central core of cork or kapok resides in variation of the core density. As cork and kapok are naturally occurring materials, little can be done to control their density. It will be appreciated that core densities which are significantly out of average will contribute to a ball falling outside of acceptable weight range limits and may cause the ball to have non-standard performance. Therefore, central cores made of cork and kapok are subject to rejection due to wide variations in density. Naturally, this contributes to increasing the expense of the finished game ball.
A further problem associated with a baseball or softball of traditional construction resides in the physical distribution of the ball's mass within the structure of the ball. The traditional solid central core centralizes the mass of the ball, resulting in a lower moment of inertia when compared to a ball having its mass distributed nearer its exterior surface. A lower moment of inertia manifests itself in certain aspects of ball performance such as a higher spin rate and an increased influence from Magnus effect. The net effect of higher spin rates and increased Magnus effect makes such a ball tend to fly higher and/or curve more strongly in flight. For play in confined areas or for use as a “training ball” by less skilled players, a ball with a higher moment of inertia and consequently, lower spin rate and less Magnus effect influence is preferred.
It is therefore a goal of sporting goods manufacturers to develop game balls, such as baseballs and softballs, which have the look, feel and handling characteristics of traditional game balls but which are economical for the consumer to use and are highly durable. In addition, it is a goal of sporting goods manufacturers to develop such game balls which have play characteristics including lower spin rate and lower influence from Magnus effect. To this end a number of balls have been developed wherein the traditional central core materials of cork and kapok are replaced with various non-traditional materials, the central core has new configurations or in some balls, the windings are eliminated.
U.S. Pat. No. 5,035,425 discloses a non-regulation light weight play ball comprising a spherical shell of high density elastomeric polyurethane material wherein the shell has a wall thickness believed to be sufficient to return the shell to its original shape following deformation from bat impact. The central core may be hollow or optionally filled with a low-density foam. Preferably, the shell has a thickness in the range of {fraction (1/16)} to ¼ inch (approximately 1.60-6.41 mm).
U.S. Pat. No. 4,610,071 relates to a method of making a game ball, such as a baseball or softball. The method includes forming two hemispherical shells of a polyolefin material, placing within the hemispherical shells chemicals which, when they react, expand to form a plastic foam material. The two hemispherical shells are welded together and the foaming materials react to fill the hollow central core within the welded hemispheres with a plastic foam. A cover may then be sewn in place over the core structure.
U.S. Pat. No. 4,880,233 discloses a game ball that is both lighter and softer than regulation game balls. The game ball of the '233 patent is comprised of a resilient, central core tightly enclosed within a durable cover. The core is formed from two hemispherical shells molded from a rubber-based compound. The hemispherical shells define a hollow central core that may optionally be pressurized relative to the ambient atmospheric pressure in order to impart specific desired rebound characteristics to the game ball. The composition of the core includes 30-40 wt. % of a styrene butadiene rubber, 16-20 wt. % natural rubber, 33-37 wt. % calcium carbonate, and 5-9 wt. % silica powder.
U.S. Pat. No. 4,861,028 discloses a softball comprising a hollow spherical central core and a leather cover which surrounds the core. The spherical core is molded from a mixture of low-density polyethylene and ethylene acid copolymer resin. The '028 patent discloses that a desired coefficient of restitution of about 0.47-0.52 for the ball may be obtained when the core comprises 40-90 weight percent low density polyethylene and 10-60 weight percent of ethylene acid copolymer. The spherical core disclosed is preferably manufactured using conventional rotational molding techniques.
While the hollow balls previously known in the art may have a higher moment of inertia than do baseballs and softballs of traditional construction, they often tend to “oil can” or become permanently dented upon making solid striking contact with a baseball bat. Balls having a foamed core, as in U.S. Pat. Nos. 4,610,071 and 5,035,425, tend to resist permanent dents better than hollow core balls due to the structural support provided by the foam. However, a foamed core typically tends to concentrate mass toward the ball's center, lower moment of inertia and thus increase the rate of spin and Magnus effect influence, both of which are preferably avoided in a ball intended for play in a confined area or for a ball to be used by less skilled players.
SUMMARY OF THE INVENTION
An object of the invention is to provide a game ball with a center core having a hollow cavity which is resistant to permanent deformation or damage from making striking contact with a bat.
Another object of the present invention is to provide a game ball having the look and feel of a softball of traditional construction, but which has a hollow central core.
A further object of the present invention is to provide a game ball, such as a softball, which is less costly to manufacture than a game ball made using traditional construction techniques, yet retains the look and feel of a traditional softball.
A still further object of the present invention is to provide a game ball having a higher moment of inertia compared to a softball of traditional construction.
Other objects will be in part obvious and in part pointed out more in detail hereinafter. These and related objects are achieved by providing a game ball with a core defining a hollow central cavity. The core is preferably spherical in shape. The core is formed of a thermoset elastomeric material which, after molding and curing, may be characterized as a hard, rubber-like substance. The combination of the hard elastomeric material, selected for its physical properties, and the thickness of the core walls provide a ball which is less likely to “oil can” or otherwi
Russell Asset Management Inc.
Thomas Kayden Horstemeyer & Risley LLP
Wong Steven
LandOfFree
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