Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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GOLF BAI.L DIMPLB PATTERN
~ACgGROlJND OF THE lr~vls~..ION
This invention relates generally to golf balls and, in
particular, to a geodesic pattern for arranging dimples in an
outer spherical surface of a golf ball.
Dimples provide golf balls with important aerodynamic
characteristics. For example, dimples create a blanket of
air turbulence around a golf ball which reduces drag and
thereby increases distance. Dimples also enhance lift as a
golf ball spins in a backward direction after being struck by
a golf club. When a golf ball is backspinning, the dimples
improve air flow above the golf ball thereby resulting in
increased air pressure below the golf ball which enhances
lift.
It is known that lift and drag can be altered by
arranging the dimples in different geodesic patterns such as
icosahedrons, octahedrons and dodecahedrons. If lift is
increased, a golf ball has a higher trajectory. If drag is
reduced, a golf ball travels farther. A proper combination
of lift and drag gives satisfactory performance.
Presently, three types of golf balls are being used.
Three-piece golf balls have a small core around which
windings are wrapped, and a cover in which dimples are
formed. Two-piece golf balls have a large core with no
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windings, and a cover with dimples formed therein. One-piece
golf balls have a unitary core and cover. A further
aerodynamic characteristic of a golf ball is spin rate which
is determined by cover hardness relative to core hardness.
Generally, three-piece golf balls have a higher spin rate
than two-piece and one-piece golf balls. Therefore, a
particular dimple pattern may result in satisfactory
performance on a three-piece golf ball but unsatisfactory
performance on a two-piece or one-piece golf ball.
Geodesic dimple patterns for golf balls have many
variations. One such variation is a truncated octahedron
wherein dimples are arranged in six square regions and eight
hexagonal regions. Truncated octahedral dimple patterns are
disclosed in U.S. Patent Nos. 4,765,626 to Gobush and
4,886,277 to Mackey. Since most commercially available golf
balls have a cover constructed with a straight seam or
parting line lying on an equator of the golf ball, the dimple
patterns disclosed by Gobush and Mackey utilize false seams
or false parting lines to improve their geometric symmetry.
The straight seam or parting line is actually a dimple-free
great circular path on the outer spherical surface of a golf
ball that results from a conventional molding process used in
making golf balls. U.S. Patent No. 4,653,758 to Karsten
Solheim discloses a method of making a golf ball wherein the
cover has a seam that is undulating rather than straight and
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thus does not require the use of false seams to improve the
geometric symmetry of the dimple pattern.
In addition to being geometrically symmetrical, a golf
ball should also have what is referred to as "spherical
symmetry" by the United States Golf Association (USGA).
Spherical or aerodynamic symmetry is determined by launching
a golf ball so that it spins about one axis and then
launching the same golf ball so that it spins about another
axis. Any differences in length of flight (i.e. carry) and
time of flight are noted. In order to conform to the USGA
Rules of Golf, these differences must not be more than three
yards for carry or greater than 0.20 seconds for flight time.
While the dimple patterns discloses in the above-mentioned
Gobush and Mackey patents may improve a golf ball's geometric
symmetry, they may adversely affect its aerodynamic symmetry.
~UMMARY OF THE IN~ENTION
An object of the present invention is to provide a
geodesic dimple pattern for golf balls which results in
improved aerodynamic characteristics on three-piece,
two-piece and one-piece golf balls.
Another object of the present invention is to provide a
geodesic dimple pattern for golf balls which reduces drag and
enhances lift.
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A further object of the present invention is to provide
a geodesic dimple pattern for golf balls that results in a
golf ball being both geometrically and aerodynamically
symmetrical without utilizing false seams or false parting
lines.
The present invention provides a golf ball having an
outer spherical surface with dimples formed therein and
arranged in a geodesic pattern defined by a plurality of
immaginary grid lines which divide the outer spherical
surface into a truncated octahedron having six square regions
and eight hexagonal regions. Each hexagonal region is
defined by six of the grid lines which form a spherical
equilateral hexagon having six sides of equal length and
three diagonals of equal length. The dimples are arranged so
that alternating sides of the hexagon each intersect at least
two dimples and each diagonal intersects at least seven
dimples.
Each square region contains a first plurality of
dimples, and each hexagonal region contains a second
plurality of dimples which is greater than the first
plurality of dimples. The outer spherical surface of the
golf ball has no great circular paths that are dimple free.
In the preferred embodiment of the present invention,
the dimples intersected by the alternating sides of each
hexagon have a first diameter and two of the dimples
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intersected by each diagonal of each hexagon have a second
diameter. The first diameter is larger than the second
diameter. The golf ball has a total of 374 dimples including
200 dimples with the first diameter which is approximately
0.165 inch, 48 dimples with the second diameter which is
approximately 0.125 inch, and 126 dimples with a third
diameter of approximately 0.145 inch.
~RIEF DESCRIPTION OF THE DRAWING8
Fig. 1 is a top plan or polar view of a golf ball with a
dimple pattern according to the present invention;
Figs. 2 and 3 are side elevational or equatorial views
of the golf ball shown in Fig. 1; and
Fig. 4 is a schematic view of one hexagonal region of
the dimple pattern shown in Figs. 1 and 2.
DE~CRIPTION OF THE PREFERRED EMBODINENT
Referring to Figs. 1 and 2, a golf ball 10 has an outer
spherical surface 12 divided by a plurality of imaginary grid
lines 14 into a geodesic pattern such as a truncated
octahedron having six identical square regions 16 and eight
identical hexagonal regions 18. Two of the square regions 16
are located in polar sections of the outer spherical surface
12 while the other four square regions 16 are located in
equatorial sections of the outer spherical surface 12.
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Each square region 16 is bounded by four hexagonal
regions 18, and each hexagonal region 18 is bounded by four
square regions 16 and two hexagonal regions 18. The
truncated octahedral dimple pattern of the present invention
has the same appearance when viewed in either the polar view
of Fig. 1 or the equatorial view of Fig. 2.
As best seen in Fig. 4, each hexagonal region 18 is
defined by six of the grid lines 14 which form a spherical
equilateral hexagon H with six vertex points A, B, C, D, E, F
and six sides AB, BC, CD, DE, EF, FA of equal length. Each
hexagon H also has three diagonals of equal length designated
AD, BE, CF in Fig. 3 extending between the six vertex points
A, B, C, D, E, F. The three diagonals AD, BE, CF intersect
at a central point G.
Referring to Fig. 3, the golf ball 10 includes a core
(not shown) and a cover 20 formed of upper and lower
substantially hemispherical sections 22 and 24. A seam or
parting line 26 exists where the hemispherical sections 22,
24 of the cover 20 are joined together during a conventional
molding process. The cover 20 may be compression molded or
injection molded. The seam 26 extends generally along an
equator 28 of the golf ball 10, and is formed in an
undulating manner similar to that disclosed in U.S. Patent
No. 4,653,758 granted March 31, 1987 to Karsten Solheim,
~p. ~ r;
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Dimples 30, 32 and 34 are formed in the outer spherical
surface 12 and are arranged in the square and hexagonal
regions 16, 18 of the truncated octohedral pattern. Thirteen
of the dimples 30 are contained in each square region 16, and
six of the dimples 30 are contained in each of the hexagonal
regions 18. Twenty-five of the dimples 32 and six of the
dimples 34 are also contained inside each of the hexagonal
regions 18. The dimples 34 are arranged adjacent the vertex
points of the hexagonal regions 18. Each square region 16
contains a plurality of thirteen dimples, and each hexagonal
region 18 contains a plurality of thirty-seven dimples so
that the golf ball 10 has a total of 374 dimples formed in
its outer surface 12.
In each of the hexagonal regions 18, the dimples 30, 32
and 34 are arranged so that alternating sides BC, DE, FA of
the hexagon H each intersect two of the dimples 32, while the
diagonals AD, BE, CF each radially intersect a total of seven
dimples (i.e. five of the dimples 30, and two of the dimples
34). This dimple arrangement results in improved aerodynamic
characteristics for the golf ball 10 by reducing drag and
enhancing lift.
In the preferred embodiment of the golf ball 10, the
dimples 30 have a diameter of approximately 0.145 inch, the
dimples 32 have a diameter of approximately 0.165 inch, and
the dimples 34 have a diameter of approximately 0.125 inch.
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The dimples 30 and 32 have a depth of about 0.0115 inch, and
the dimples 34 have a depth of about 0.0105 inch. Therefore,
the diameter to depth ratios for the dimples 30, 32 and 34
are 12.6 to 1, 14.3 to 1, and 11.9 to 1, respectively. The
golf ball 10 has a total of 374 dimples which includes 126
dimples with the 0.145 inch diameter, 200 dimples with the
0.165 inch diameter, and 48 dimples with the 0.125 inch
diameter. Since 76.8 per cent of the outer surface 12 of the
golf ball 10 is covered by the dimples 30, 32 and 34, only
23.2 per cent of the outer surface 12 is undimpled.
The golf ball 10 may be of either the three-piece type
which has a small core around which windings are wrapped, the
two-piece type which has a large core and no windings, or the
one-piece type which has a unitary core and cover.
It will be understood that the present invention
provides an improved dimple pattern for use on three-piece,
two-piece and one-piece golf balls.
Unlike the dimple patterns disclosed in U.S. Patent Nos.
4,765,626 to Gobush and 4,886,277 to Mackey, the dimple
pattern of the present invention does not utilize any false
seams or false parting lines to improve its geometric
symmetry. Furthermore, with the dimple pattern of the
present invention, the outer spherical surface of a golf ball
has no great circular paths that are dimple free.
