Golf ball

Abstract

Golf balls including at least one modified dimple group are disclosed. The modified dimple group comprises one or more modified dimples forming an axially symmetric pattern about a Correction Area Centroid located on an axis of symmetry at a latitude greater than 0°, where 0° represents the hemispherical pole and 90° represents the equator. The modified dimples can be altered, for example, by changing dimple coverage, dimple diameter, dimple depth, dimple edge angle, dimple volume, dimple cross-sectional shape, and/or dimple plan shape. Optionally, the dimples have a catenary cross-sectional shape and the modified dimples are altered by changing the shape factor and/or chord depth. Such modifications preferably produce a golf ball that flies more consistently regardless of orientation when struck than a corresponding golf ball without such modifications.

Claims

1. A golf ball having dimples on the outermost surface thereof, wherein the dimples have a catenary cross-sectional shape and consist of a majority of unmodified dimples and a plurality of modified dimples; wherein the catenary cross-sectional shape of each unmodified dimple is expressed by the following formula: $Y=\frac{d\left(\cosh \left(a_{U}x\right)-1\right)}{\cosh \left(a_{U}r\right)-1}$ where: Y is the vertical distance from the dimple apex; x is the radial distance from the dimple apex to the dimple surface; a.sub.U is a constant from 20 to 100, and is the same for all of the unmodified dimples; d is the depth of the dimple; and r is the radius of the dimple; wherein the catenary cross-sectional shape of each modified dimple is expressed by the following formula: $Y=\frac{d\left(\cosh \left(a_{M}x\right)-1\right)}{\cosh \left(a_{M}r\right)-1}$ where: Y is the vertical distance from the dimple apex; x is the radial distance from the dimple apex to the dimple surface; a.sub.M is a constant from 20 to 100; d is the depth of the dimple; and r is the radius of the dimple; wherein a.sub.M is at least 10% greater than or at least 10% less than a.sub.U; and wherein the modified dimples are arranged in two or more groups, each group consisting of the modified dimples and forming an axially symmetric pattern about a different geometric center.

2. The golf ball of claim 1, wherein the geometric center of each group of modified dimples is located on a non-polar axis of the ball.

3. The golf ball of claim 1, wherein the geometric center of each group of modified dimples is located on an axis of the ball located at a latitude angle of greater than 5°.

4. The golf ball of claim 1, wherein the geometric center of each group of modified dimples is located on an axis of the ball located at a latitude angle of greater than 15°.

5. The golf ball of claim 1, wherein the geometric center of each group of modified dimples is located on an axis of the ball located at a latitude angle of greater than 30°.

6. The golf ball of claim 1, wherein the geometric center of each group of modified dimples is located on an axis of the ball located at a latitude angle of greater than 45°.

7. The golf ball of claim 1, wherein the geometric center of each group of modified dimples is located on an axis of the ball located at a latitude angle of greater than 50°.

8. The golf ball of claim 1, wherein the modified dimples are arranged in six to eight groups.

9. The golf ball of claim 1, wherein the pattern of one group of modified dimples is different from the pattern of another group of modified dimples.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith, and in which like reference numerals are used to indicate like parts in the various views:

(2) FIG. 1 is a polar view of a golf ball having an arrangement of modified dimples according to an embodiment of the present invention.

(3) FIG. 2 is a polar view of a golf ball having an arrangement of modified dimples according to another embodiment of the present invention.

(4) FIG. 3 is a polar view of a golf ball having an arrangement of modified dimples according to another embodiment of the present invention.

(5) FIG. 4 is a polar view of a golf ball having an arrangement of modified dimples according to another embodiment of the present invention.

(6) FIG. 5 is a polar view of a golf ball having an arrangement of modified dimples according to another embodiment of the present invention.

(7) FIG. 6A is a polar view of a golf ball having an arrangement of modified dimples according to another embodiment of the present invention.

(8) FIG. 6B is an equatorial view of the golf ball illustrated in FIG. 6A.

DETAILED DESCRIPTION

(9) While the present invention is not meant to be limited by any particular pattern of the overall dimple arrangement, golf balls of the present invention preferably have an overall dimple pattern formed by generating one or more domains from a polyhedron, and tessellating the domain(s) over the ball, as disclosed, for example, in U.S. Patent Application Publication No. 2010/0113187, the entire disclosure of which is hereby incorporated herein by reference. By arranging dimples in this manner, the symmetry of the underlying polyhedron is preserved and great circles due to parting lines are eliminated. The resulting overall dimple pattern has multiple axes of symmetry, typically including a polar symmetry axis and multiple non-polar symmetry axes. For purposes of the present disclosure, the symmetry axes are lines about which the overall dimple pattern can be rotated through some angle smaller than 360° which brings the pattern to a new orientation which appears identical to its starting position. The symmetry axes of an overall dimple pattern on a golf ball necessarily intersect at a common point at the center of the ball.

(10) Golf balls of the present invention include, on each hemisphere of the ball, at least one modified dimple group having a geometric center, also referred to herein as a Correction Area Centroid (“CAC”), located on one of the multiple axes of symmetry in the overall dimple pattern, preferably a non-polar axis of symmetry. Preferably, the modified dimple group is located such that its CAC is located at a latitude angle (“φ.sub.CAC”) of greater than 0°, or greater than 5°, or greater than 15°, or greater than 30°, or 45° or greater, or greater than 45°, or 50° or greater, or at a φ.sub.CAC within a range having a lower limit of 5° or 15° or 30° or 35° or 40° or 45° and an upper limit of 55° or 60° or 65° or 75° or 80° or 90°, where 0° represents the hemispherical pole and 90° represents the equator.

(11) Modified dimple groups of the present invention include groups of one or more modified dimples. For purposes of the present invention, the term “modified” means altered from the typical configuration based on the overall pattern of dimples on the ball, and the term “dimple” includes any texturizing on the surface of a golf ball, e.g., depressions and projections, which may have a variety of planform shapes, including, but not limited to, circular, polygonal, oval, or irregular shapes, and a variety of cross-sectional shapes, including, but not limited to, circular, catenary, elliptical, or conical shapes.

(12) The approximate total number of dimples to be modified and the location of the modified dimple groups on the outermost surface of the ball are determined based on the flight performance of the ball prior to modifying dimples and the desired flight performance of the final product. Preferably, the same modifications are performed on both hemispheres of the ball, i.e., the ball consists of identical hemispheres.

(13) The pattern of each modified dimple group can vary substantially, and the present invention is not meant to be limited by any particular pattern. Preferably, each modified dimple group has a pattern that is axially symmetric, i.e., symmetric about the axis of symmetry containing the group's CAC. In embodiments of the present invention wherein each hemisphere includes two or more modified dimple groups, the pattern formed by one group can be the same as or different than the pattern formed by another group.

(14) While the degree of dimple modification depends on the ball's overall dimple pattern and the total number of dimples, the total number of modified dimples is preferably ¼ of the total number of dimples or less.

(15) The modified dimples can be altered in any suitable manner, including, but not limited to, modifying diameter, depth, volume, edge angle, edge radius, cross-sectional shape, perimeter shape, and any combination of two or more thereof. In a particular embodiment, the majority of the unmodified dimples have a catenary cross-sectional shape and each of the modified dimples has a catenary cross-sectional shape, wherein each of the modified dimples has a shape factor and/or a chord depth that is different than the shape factor and/or chord depth of the catenary-shaped unmodified dimples. In a particular aspect of this embodiment, each modified dimple has a shape factor that is at least 10%, or at least 20%, different than that of the unmodified dimples, or a shape factor that is from 10% or 20% or 25% to 45% or 50% or 60% different than that of the unmodified dimples. Each modified dimple can have the same shape factor or a different shape factor than the other modified dimples. The shape factor is an independent variable in the mathematical function that defines a catenary dimple cross-sectional shape, as further disclosed in, for example, U.S. Pat. No. 6,796,912 to Dalton et al., U.S. Pat. No. 7,163,472 to Dalton et al., U.S. Pat. No. 7,491,137 to Bissonnette et al., and U.S. Pat. No. 7,887,439 to Aoyama et al., the entire disclosures of which are hereby incorporated herein by reference. In another particular aspect of this embodiment, each modified dimple has a chord depth that is at least 0.0001 inches, or at least 0.0002 inches, different than that of the unmodified dimples, or a chord depth that is from 0.0001 inches or 0.0002 inches to 0.0005 inches or 0.0010 inches different than that of the unmodified dimples. Each modified dimple can have the same chord depth or a different chord depth than the other modified dimples. In one embodiment of the present invention, the mathematical equation for describing the catenary cross-sectional profile of a dimple is expressed by the following formula:

(16) $Y=\frac{d\left(\cosh \left(\mathrm{ax}\right)-1\right)}{\cosh \left(\mathrm{ar}\right)-1}$
where:

(17) Y is the vertical distance from the dimple apex;

(18) x is the radial distance from the dimple apex to the dimple surface;

(19) a is a shape constant (also called shape factor);

(20) d is the depth of the dimple; and

(21) r is the radius of the dimple.

(22) The shape factor may be used to independently alter the volume ratio of the dimple while holding the dimple depth and radius fixed. The volume ratio is the fractional ratio of the dimple volume divided by the volume of a cylinder defined by a similar radius and depth as the dimple. Use of the shape factor provides an expedient method of generating alternative dimple profiles, for dimples with fixed radii and depth. For example, if a golf ball designer desires to generate balls with alternative lift and drag characteristics for a particular dimple position, radius, and depth on a golf ball surface, then the golf ball designer may simply describe alternative shape factors to obtain alternative lift and drag performance without having to change these other parameters. No modification to the dimple layout on the surface of the ball is required. Preferably, shape factors are between about 20 to about 100.

(23) In a particular embodiment, one or more dimple groups are modified in such a way as to make them less aggressive aerodynamically, such as by reducing dimple diameter, depth, volume, and/or edge angle. In another particular embodiment, one or more dimple groups are modified in such a way as to make them more aerodynamically aggressive, such as by increasing edge angle, volume, and/or by adding sub-dimples, i.e., dimples within a dimple. Sub-dimples are further disclosed, for example, in U.S. Pat. No. 6,569,038, the entire disclosure of which is hereby incorporated herein by reference.

(24) For dimples modified by altering the edge angle, the difference in the edge angle between the majority of the dimples and the edge angle of the modified dimples is preferably 4° or less, more preferably from 1° to 3°.

(25) The modified dimples can retain essentially the same appearance as or can be visually different from the unmodified dimples. Alterations that typically, but do not necessarily, result in modified dimples that retain essentially the same appearance as the unmodified dimples include, but are not limited to, changes to the dimple edge angle, depth, and volume, moderate changes to the cross-sectional profile, and moderate changes to the shape factor of catenary dimples. Alterations that typically, but do not necessarily, result in modified dimples that are visually different from the unmodified dimples include, but are not limited to, changes to the dimple diameter, plan shape and size, substantial changes to the cross-sectional profile, and substantial changes to the shape factor of catenary dimples. Dimples of the present invention having a modified depth preferably have a depth that is not greater than 90%, more preferably not greater than 80%, of the thickness of the outermost layer of the golf ball. Some dimples may be removed from the pattern by reducing their volume by about 100% to about zero. In this embodiment, by virtue of the types or magnitudes of the changes, the modified dimples are visually different from the unmodified dimples.

(26) In embodiments of the present invention wherein each hemisphere includes two or more modified dimple groups, the dimples of one group may be altered in the same manner as or a different manner than another. Similarly, one dimple may be altered in the same or a different way than another dimple in the same dimple group.

(27) Referring now to the figures, FIGS. 1-5 illustrate the polar view of a seamless golf ball having 352 dimples arranged in a tetrahedron-based pattern, with modified dimples designated by the letter A. Each hemisphere of the ball can be divided by imaginary grid lines into two pairs of identical regions, each region having one modified dimple group arranged about a CAC 10 located on a non-polar axis of symmetry at a latitude angle of 54.7°. In FIG. 1, each region of one pair has a modified dimple group consisting of a set of three pairs of modified dimples, and each region of the other pair has a modified dimple group consisting of six modified dimples forming a hexagon. In FIG. 2, each region of one pair has a modified dimple group consisting of seven modified dimples forming a hexagon, and each region of the other pair has a modified dimple group consisting of three modified dimples forming a triangle. In FIG. 3, each region of one pair has a modified dimple group consisting of six modified dimples forming a triangle, and each region of the other pair has a modified dimple group consisting of three modified dimples forming a triangle and a modified dimple at or near the center of the triangle. FIGS. 4 and 5 illustrate two additional non-limiting examples of suitable patterns for modified dimples of the present invention.

(28) FIG. 6A illustrates the polar view of a seamless golf ball having 360 dimples arranged in a cuboctahedron-based pattern, with modified dimples designated by the letter A. Each hemisphere of the ball can be divided by imaginary grid lines into three identical regions, each region having one modified dimple group arranged about a CAC 10 located on a non-polar axis of symmetry at a latitude angle of 54.7°. The modified dimple group of each region consists of four modified dimples forming a square and a set of four pairs of modified dimples forming a square. FIG. 6B is an equatorial view of the golf ball illustrated in FIG. 6A.

(29) Modifying dimples according to the present invention preferably produces a golf ball with improved flight symmetry compared to a corresponding golf ball without the modified dimples.

(30) In a particular embodiment, the present invention is directed to a seamless golf ball, wherein the dimples have been modified using the dimple modification method disclosed herein. Seamless golf balls and methods of producing such are further disclosed, for example, in U.S. Pat. Nos. 6,849,007 and 7,422,529, the entire disclosures of which are hereby incorporated herein by reference.

(31) While golf balls of the present invention are not limited to a particular dimple count, in a particular embodiment, the golf ball has a dimple count of 302 or 312 or 328 or 342 or 348 or 352 or 364 or 376 or 388.

(32) When numerical lower limits and numerical upper limits are set forth herein, it is contemplated that any combination of these values may be used.

(33) All patents, publications, test procedures, and other references cited herein, including priority documents, are fully incorporated by reference to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.

(34) While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those of ordinary skill in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein, but rather that the claims be construed as encompassing all of the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those of ordinary skill in the art to which the invention pertains.