Games using tangible projectile – Golf – Ball
Reexamination Certificate
1998-10-01
2001-05-29
Graham, Mark S. (Department: 3711)
Games using tangible projectile
Golf
Ball
Reexamination Certificate
active
06238305
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a wound golf ball having satisfactory spin, feel and durability and featuring increased distance.
2. Prior Art
In prior art wound golf balls each having a solid center, thread rubber and a cover, the cover is often formed of ionomer resins and balata rubber. Covers of two-layer structure are also known. Although many attempts have been made on wound golf balls to improve the spin properties and distance thereof, there is still a desire for further improvements.
In general, the spin properties of golf balls are determined by an amount of deformation of the ball upon impact and the frictional force between the ball and the club face. The ball shows the tendency that the spin rate decreases as the deformation amount of the ball upon impact becomes greater, and also as the cover becomes harder.
In order to improve the controllability of the ball upon iron shots, it is required that the cover be made soft and the deformation amount of the ball be optimized relative to the cover hardness.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a wound golf ball which has appropriate spin properties compatible with different clubs and which is improved in durability, hitting feel and flight distance.
The invention pertains to a wound golf ball comprising a wound core consisting of a solid center and a thread rubber layer thereon, and a cover surrounding the wound core. In order to improve the spin properties, hitting feel, durability and flight distance of the wound golf ball of this type, we made investigations on the respective components of the ball. We have found that by setting the surface hardness of the ball in the range of 70 to 85 on JIS C hardness scale, and setting the contact area of the ball with the club face of No. 9 iron driven at a relatively slow head speed in the range of 3.5 to 4.1 cm
2
, the wound golf ball is optimized so as to fully meet the requirements of spin properties, hitting feel and durability and travel a longer distance.
The wound golf ball is further improved in performance by optimizing the diameter and deflection of the solid center and their relationship and/or by optimizing the density of the thread rubber layer.
According to the invention, there is provided a wound golf ball comprising a wound core consisting of a solid center and a thread rubber layer, and a cover around the wound core. The ball has a surface hardness of 70 to 85 on JIS C hardness scale. The ball presents a contact area with a club face of 3.5 to 4.1 cm
2
when the ball is hit with No. 9 iron at a head speed of 35 m/s.
In one preferred embodiment, the solid center has a diameter D of 30 to 36 mm and yields a deflection C of 0.8 to 4.0 mm under an applied load of 30 kg, and C and D satisfy the following relationship:
−0.15
D+
6.2≦
C≦−
0.4
D+
16.
Also preferably, the thread rubber layer has a density of 0.65 to 0.85 g/cm
3
.
REFERENCES:
patent: 5607366 (1997-03-01), Yokota et al.
patent: 5743814 (1998-04-01), Endo
patent: 5766096 (1998-06-01), Maruko et al.
Kakiuchi Shinichi
Umezawa Junji
Bridgestone Sports Co. Ltd.
Gorden Raeann
Graham Mark S.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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