Games using tangible projectile – Golf – Ball
Reexamination Certificate
2000-01-14
2002-05-07
Graham, Mark S. (Department: 3711)
Games using tangible projectile
Golf
Ball
Reexamination Certificate
active
06383093
ABSTRACT:
BACKGROUND OF THE INVENTION
The instant invention is directed to golf balls, and more particularly to a ball having the optimal core compression, core diameter, cover hardness, and dimple configuration to provide superior playability capabilities with respect to softness and spin without sacrificing superior distance capabilities.
DESCRIPTION OF THE PRIOR ART
There are a number of physical properties that affect the performance of a golf ball. The core of the golf ball is the source of the ball's energy. Among other things, the core affects the ball's “feel” and its initial velocity. The “feel” is the overall sensation transmitted to the golfer through the golf ball after striking a ball. The initial velocity is the velocity at which the golf ball travels when first struck by the golf club. The initial velocity, together with the ball's trajectory, determine how far a shot will travel.
Until the late 1960's most golf balls were constructed as three-piece wound balls. In the three-piece wound ball, a solid or liquid-filled center is wound with rubber windings to form a core, which is then covered with a cover of compounds based on natural (balata or guttta percha) or synthetic transpolyisoprene. During the manufacturing process, after the liquid-filled center is formed, it is frozen to make it as hard as possible so that it will retain its spherical shape while the rubber thread is wrapped around it.
These three-piece wound balls were known and are still known to provide acceptable flight distance and soft feel. Additionally, due to the relative softness of the balata cover, skilled golfers are able to impart various spins on the ball in order to control the ball's flight path (e.g. “fade” or “draw”) and check characteristics upon landing on a green.
With the advent of new materials developed through advances and experimentation in polymer chemistry, two-piece golf balls were developed. The primary difference between a two-piece golf ball and a three-piece golf ball is the elimination of the rubber thread windings found in the three-piece balls. A relatively large solid core in a two-piece ball takes the place of the relatively small center and thread windings of a three-piece ball core having the same overall diameter. With the elimination of the thread windings, there is no need to freeze the core during the manufacturing process of the two-piece golf ball.
Two-piece balls have proven to be more durable than three-piece balls when repeatedly struck with golf clubs and more durable when exposed to a variety of environmental conditions. An example of these environmental conditions is the high temperature commonly experienced in an automobile trunk. In addition, two piece balls are typically less expensive to manufacture than the three-piece wound balls. However, two-piece balls are, in general, considered to have inferior characteristics of feel and workability when compared to three-piece balls. Generally and historically, two piece balls use harder cover materials for increased durability. The “hardness” of a golf ball can affect the “feel” of a ball and the sound or “click” produced at contact. “Feel” is determined as the deformation (i.e. compression) of the ball under various load conditions applied across the ball's diameter. Generally, the lower the compression value, the softer the “feel.” Consequently, two-piece golf balls have a higher initial velocity. In addition, typically two-piece golf balls have more potential energy, which is derived primarily from the core. The cores in two piece golf balls are typically larger than the centers in three-piece golf balls.
In contrast, three-piece golf balls with their smaller centers historically use softer cover materials. These softer cover materials result in a lower initial velocity when compared to two-piece golf balls. However, this difference in the initial velocity may be somewhat made up by the windings in the three-piece golf ball.
In addition to manipulating the core and cover of a golf ball, for many years golf balls have been made with surface indentations or depressions, called dimples, to improve their aerodynamic properties in flight. Specifically, ball manufacturers have looked to dimple configurations in an effort to design a ball with superior distance capabilities. Many efforts have been made to select the optimum number, size and shape of dimples as well as their disposition around the outer surface of a generally spherically shaped golf ball.
Ball manufacturers are bound by regulations of the United States Golf Association (USGA) which control many characteristics of the ball, including the size and weight of the ball, the initial velocity of the ball when tested under specified conditions, the overall distance the ball travels when hit under specified test conditions, and the ball's aerodynamic symmetry. Under USGA regulations, the diameter of the ball cannot be less than 1.680 inches, the weight of the ball cannot be greater than 1.620 ounces avoirdupois, the initial velocity of the ball cannot be greater than 250 feet per second when tested under specified conditions (with a maximum tolerance of +2%), the driver distance cannot exceed 280 yards when tested under specified conditions (with a test tolerance of +6%), and the ball must perform the same aerodynamically regardless of orientation.
While the USGA sets a limit for the distance a ball can travel under set test conditions, there is no upper limit on how far a player can hit a ball. For example, U.S. Pat. No. 4,886,277 discloses the projection of a truncated octahedron onto the ball as a basis for a dimple configuration. A truncated octahedron is formed by removing portions of the eight-sided octahedron, which results in a solid with six (6) squares, and eight (8) hexagons. The preferred ball disclosed in this reference has a minimum of four (4) uninterrupted great circle paths present on the dimpled ball, and a major portion of the dimples present on the ball are within the boundaries of either a spherical hexagon or square. U.S. Pat. No. 4,765,626 discloses a golf ball having a dimple pattern based on the truncated octahedron used in conjunction three orthogonal uninterrupted parting lines which coincide with the diagonal bisectors of the squares.
A problem with the prior art dimple configurations is that they fail to take into account other features of the ball, such as core size, core compression and cover hardness, which also influence how far a ball will travel.
U.S. Pat. No. 5,368,304 to Sullivan discloses a ball having a low spin rate, which in turn enables the ball to travel greater distances. According to the Sullivan patent, the low spin rate is the result of a soft core and hard cover. While the '304 patent discloses the use of a soft core and hard cover to lower the spin rate, it does not disclose a dimple configuration for the ball.
OBJECT OF THE INVENTION
Accordingly, it is an object of the instant invention to provide a two-piece golf ball that has a soft feel in combination with superior distance capabilities.
It is another object of the instant invention to optimize the combination of core compression, core size, core composition, dimple configuration, cover composition, and cover hardness to provide a two-piece golf ball, which travels great distances, and at the same time complies with USGA regulations.
It is yet another object of the instant invention to provide a two-piece golf ball having a synthetic cover material that achieves the sound, feel, playability and flight performance qualities of balata covered golf balls.
It is a further object of the instant invention to lower the cost of manufacturing a two-piece golf ball that has a soft feel in combination with superior distance capabilities.
It is still a further object of the instant invention is to provide a two-piece golf ball having superior distance, trajectory and flight stability.
Another object of the instant invention is to provide a two-piece golf ball having a surface divided into a plurality of polygonal configu
Kuttappa Sanjay M.
Lemons Lane D.
Stanczak Matthew B.
Wallace George R.
Dunlop Slazenger Group Americas
Gorden Raeann
Graham Mark S.
Lorusso & loud
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