Games using tangible projectile – Golf – Ball
Reexamination Certificate
1999-11-01
2001-11-13
Graham, Mark S. (Department: 3711)
Games using tangible projectile
Golf
Ball
C473S337000
Reexamination Certificate
active
06315681
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to the construction of regulation golf balls including golf balls having enhanced distance and feel characteristics. More particularly, the invention relates to improved multi-layer golf balls having one or more layers containing metal particles or other heavy weight filler materials to enhance the perimeter weight of the balls. Such weighting material may be incorporated in one or more of an inner layer or an outer layer. Preferably, the heavy weight filler particles are present in an outer cover layer. Most preferably, the weighting material is visible along the exterior of the ball. The inclusion of the particles along with the production of a smaller core produces a greater (or higher) moment of inertia. This results in less spin, reduced slicing and hooking and further distance. Additionally, the golf balls of the invention have essentially the same “feel” characteristic of softer balata covered balls.
BACKGROUND OF THE INVENTION
Golf balls utilized in tournament or competitive play today are regulated for consistency purposes by the United States Golf Association (U.S.G.A.). In this regard, there are five (5) U.S.G.A. specifications which golf balls must meet under controlled conditions. These are size, weight, velocity, driver distance and symmetry.
Under the U.S.G.A. specifications, a golf ball can not weigh more than 1.62 ounces (with no lower limit) and must measure at least 1.68 inches (with no upper limit) in diameter. However, as a result of the openness of the upper or lower parameters in size and weight, a variety of golf balls can be made. For example, golf balls are manufactured today which by the Applicant are slightly larger (i.e., approximately 1.72 inches in diameter) while meeting the weight, velocity, distance and symmetry specifications set by the U.S.G.A.
Additionally, according to the U.S.G.A., the initial velocity of the ball must not exceed 250 ft/sec. with a 2% maximum tolerance (i.e., 255 ft/sec.) when struck at a set club head speed on a U.S.G.A. machine. Furthermore, the overall distance of the ball must not exceed 280 yards with a 6% tolerance (296.8 yards) when hit with a U.S.G.A specified driver at 160 ft/sec. (clubhead speed) at a 10 degree launch angle as tested by the U.S.G.A. Lastly, the ball must pass the U.S.G.A. administered symmetry test, i.e., fly consistency (in distance, trajectory and time of flight) regardless of how the ball is placed on the tee.
While the U.S.G.A. regulates five (5) specifications for the purposes of maintaining golf ball consistency, alternative characteristics (i.e., spin, feel, durability, distance, sound, visibility, etc.) of the ball are constantly being improved upon by golf ball manufacturers. This is accomplished by altering the type of materials utilized and/or improving construction of the balls. For example, the proper choice of cover and core materials are important in achieving certain distance, durability and playability properties. Other important factors controlling golf ball performance include, but are not limited to, cover thickness and hardness, core stiffness (typically measured as compression), ball size and surface configuration.
As a result, a wide variety of golf balls have been designed and are available to suit an individual player's game. Moreover, improved golf balls are continually being produced by golf ball manufacturers with technologized advancements in materials and manufacturing processes.
Two of the principal properties involved in a golf ball's performance are resilience and compression. Resilience is generally defined as the ability of a strained body, by virtue of high yield strength and low elastic modulus, to recover its size and form following deformation. Simply stated, resilience is a measure of energy retained to the energy lost when the ball is impacted with the club.
In the field of golf ball production, resilience is determined by the coefficient of restitution (C.O.R.), the constant “e” which is the ratio of the relative velocity of an elastic sphere after direct impact to that before impact. As a result, the coefficient of restitution (“e”) can vary from 0 to 1, with 1 being equivalent to a perfectly or completely elastic collision and 0 being equivalent to a perfectly or completely inelastic collision.
Resilience (C.O.R.), along with additional factors such as club head speed, club head mass, angle of trajectory, ball size, density, composition and surface configuration (i.e., dimple pattern and area of coverage) as well as environmental conditions (i.e., temperature, moisture, atmospheric pressure, wind, etc.) generally determine the distance a golf ball will travel when hit. Along this line, the distance a golf ball will travel under controlled environmental conditions is a function of the speed and mass of the club and the size, density, composition and resilience (C.O.R.) of the ball and other factors. The initial velocity of the club, the mass of the club and the angle of the ball's departure are essentially provided by the golfer upon striking. Since club head, club head mass, the angle of trajectory and environmental conditions are not determinants controllable by golf ball producers and the ball size and weight are set by the U.S.G.A., these are not factors of concern among golf ball manufacturers. The factors or determinants of interest with respect to improved distance are generally the coefficient of restitution (C.O.R.), spin and the surface configuration (dimple pattern, ratio of land area to dimple area, etc.) of the ball.
The coefficient of restitution (C.O.R.) in solid core balls is a function of the composition of the molded core and of the cover. The molded core and/or cover may be comprised of one or more layers such as in multi-layered balls. In balls containing a wound core (i.e., balls comprising a liquid or solid center, elastic windings, and a cover), the coefficient of restitution is a function of not only the composition of the center and cover, but also the composition and tension of the elastomeric windings. As in the solid core balls, center and cover of a wound core ball may also consist of one or more layers.
The coefficient of restitution of a golf ball can be analyzed by determining the ratio of the outgoing velocity to the incoming velocity. In the examples of this writing, the coefficient of restitution of a golf ball was measured by propelling a ball horizontally at a speed of 125+/−1 feet per second (fps) against a generally vertical, hard, flat steel plate and measuring the ball's incoming and outgoing velocity electronically. Speeds were measured with a pair of Oehler Mark 55 ballistic screens (available from Oehler Research Austin Tex.), which provide a timing pulse when an object passes through them. The screens are separated by 36″ and are located 25.25″ and 61.25″ from the rebound wall. The ball speed was measured by timing the pulses from screen 1 to screen 2 on the way into the rebound wall (as the average speed of the ball over 36″), and then the exit speed was timed from screen 2 to screen 1 over the same distance. The rebound wall was tilted 2 degrees from a vertical plane to allow the ball to rebound slightly downward in order to miss the edge of the cannon that fired it.
As indicated above, the incoming speed should be 125+/−1 fps. Furthermore, the correlation between C.O.R. and forward or incoming speed has been studied and a correction has been made over the +/− fps range so that the C.O.R. is reported as if the ball had an incoming speed of exactly 125.0 fps.
The coefficient of restitution must be carefully controlled in all commercial golf balls if the ball is to be within the specifications regulated by the U.S.G.A. As mentioned to some degree above, the U.S.G.A. standards indicate that a “regulation” ball cannot have an initial velocity exceeding 255 feet per second in an atmosphere of 75° F. when tested on a U.S.G.A. machine. Since the coefficient of restitution of a ball is
Gorden Raeann
Graham Mark S.
Spalding Sports Worldwide Inc.
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