Classifications

• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/14—Special surfaces
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
  • A63B37/0004—Surface depressions or protrusions
  • A63B37/0007—Non-circular dimples
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
  • A63B37/0004—Surface depressions or protrusions
  • A63B37/0007—Non-circular dimples
  • A63B37/0011—Grooves or lines
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/12—Special coverings, i.e. outer layer material

Definitions

• the present invention is related to a golf ball, and more particularly, to a golf ball which has not only an air resistance similar to or smaller than that of a dimpled golf ball, but also a significantly reduced area ratio of grooves relative to the total surface area of the golf ball, thereby achieving an enhanced carry distance and high accuracy in the directionality of putting.
• a golf ball which has a spherical surface divided into many spherical polygonal faces each being arranged with a circular dimple, has been used for a long time.
• Such a conventional dimpled golf ball is known to fulfill the symmetry of a spherical surface while achieving a reduced air resistance and consequently an increased carry distance thereof.
• examples of widely used divisional compositions of a sphere include a spherical icosahedron, a spherical icosi-dodecahedron, a spherical dodecahedron, a spherical octahedron, a spherical hexahedron, a spherical hexa-octahedron, or other further divided spherical polyhedrons having smaller faces.
• the above mentioned spherical divisional compositions can be actually overlapped with one another except for specially deformed ones.
• the dimpled golf ball is subjected to strong repulsive elasticity by a force applied from the head of a golf club, and simultaneously has a back spin by a loft angle of the club head.
• the dimpled golf ball has an initial flying velocity of approximately 190 to 300 km/hr and an initial back spin of approximately 2200 to 4500 rpm.
• dimples of the golf ball act to create a turbulent flow on the surface of the golf ball and in turn, the turbulent flow acts to delay the separation of air streams around the golf ball, thereby reducing a pressure difference between front and rear portions of the dimpled golf ball, and resulting in a reduction of air resistance acting on the golf ball.
• the area ratio of dimples relative to the total surface area of the golf ball has to be more than 75%. This makes it impossible to achieve a high accuracy in the directionality of putting.
• a putter 2 generally strikes irregular faces formed with the dimples of the dimpled golf ball 1 and this makes the golf ball 1 to move in a direction slightly different from the golfer's intension. In other words, the golf ball deviates from a hole cup even by an extremely small angular error occurred in putting.
• the present invention has been made in view of the above problems, and the objective of the present invention is to provide a golf ball which has not only an air resistance similar to or smaller than that of a dimpled golf ball by virtue of net-shaped grooves formed in a spherical surface thereof, but also a significantly reduced area ratio of the grooves relative to the total surface area of the golf ball, thereby achieving an enhanced carry distance and high accuracy in the directionality of putting.
• a golf ball has net-shaped grooves formed throughout a sphere.
• an air resistance acting on the golf ball is similar to or smaller than that acting on a dimpled golf ball, thus resulting in an improvement in the carry distance of the golf ball.
• FIG. 1 is a perspective view illustrating a dimpled golf ball in a putting position
• FIG. 2 is a sectional view taken along the line A-A of FIG. 1;
• FIG. 3 is a plan view illustrating a golf ball formed with grooves according to an embodiment of the present invention
• FIG. 4 is a schematic diagram of the grooves according to one embodiment of the present invention
• FIG. 5 is a schematic diagram of the grooves according to another embodiment of the present invention
• FIG. 6 is a schematic diagram of the grooves according to yet another embodiment of the present invention
• FIG. 7 is a photograph illustrating laboratory equipment having a model of a golf ball according to the present invention
• FIG. 8 is a schematic diagram illustrating grooves formed in the surface of the model of the golf ball according to the present invention
• FIG. 24 is a schematic diagram of the grooves formed in the surface of the model of the golf ball according to the present invention
• FIG. 9 is a photograph illustrating a model of a golf ball according to the present invention, which has grooves and protrusions formed at intervals along the grooves;
• FIGS. 10 and 13 are graphs illustrating the relationship between the Reynolds number and the air resistance coefficient;
• FIGS. 11 and 14 are graphs illustrating the relationship between the velocity of a golf ball and the air resistance;
• FIG. 12 is a photograph illustrating another model of a golf ball according to the present invention, which has grooves and protrusions continuously formed along the grooves; and
• FIG. 15 is a partial sectional view of a golf ball having grooves and protrusions formed along the grooves according to the present invention.
• the present invention provides a golf ball in which net-shaped grooves are formed on the outer surface of a sphere.
• net-shaped grooves are formed on the outer surface of a sphere.
• the golf ball in accordance with a preferred embodiment of the present invention includes net-shaped grooves 20 formed on the outer surface of a sphere 10.
• the net-shaped grooves 20 may be connected to or separated from one another.
• each groove 20 can be freely selected among a variety of different shapes so long as all the grooves 20 have a net shape.
• a spherical regular polyhedron is inscribed in the sphere 10 such that vertexes 31 of spherical regular polygons constituting the spherical regular polyhedron touch on the sphere 10.
• certain specific points 33a on a spherical surface of the sphere 10 are determined such that an included angle ⁇ between a straight line 32 connecting one of the vertexes 31 to a center 11 of the sphere 10 and a straight line 34 connecting the center 11 of the sphere 10 to one of the specific points 33a has a predetermined value.
• circular paths 35 are defined on the surface of the sphere 10 by connecting the specific points 33a to one another.
• the grooves 20 can be formed along the circular paths 35.
• each edge of the regular polyhedron is defined by connecting every two adjacent vertexes 31 to each other via the shortest path on the surface of the sphere 10.
• the spherical regular polyhedron may be a spherical regular hexahedron or regular icosahedron, and the included angle ⁇ may be 45 to 80 degrees.
• the spherical regular hexahedron has six spherical squares and eight vertexes 31, and the spherical regular icosahedron has twenty spherical regular triangles and twelve vertexes 31. Therefore, when each groove is formed along one associated circular path 35 defined about each vertex 31 and consequently, eight or twelve grooves are formed in the surface of the sphere 10 such that they are connected to one another, all the grooves 20 occupy only a small area ratio relative to the surface area of the golf ball.
• the groove be formed on the basis of the included angle ⁇ of 45 to 80 degrees.
• a spherical regular polyhedron which consists of spherical regular polygons each having a center of gravity 36, is inscribed in the sphere 10, and specific points 33b on the surface of the sphere 10 are determined such that an included angle ⁇ between a straight line 37 connecting one of the centers of gravity 36 to the center 11 of the sphere 10 and a straight line 38 connecting the center 11 of the sphere 10 to one of the specific points 33b has a predetermined value. If the specific points 33b are determined, circular paths 39 connecting the specific points 33b to one another are defined on the surface of the sphere 10. The grooves 20 can be formed along the circular paths 39.
• the spherical regular polyhedron is a spherical regular octahedron or regular dodecahedron, and the included angle ⁇ is 45 to 80 degrees.
• the spherical regular octahedron has eight spherical regular triangles and six vertexes 31, and the spherical regular dodecahedron has twelve spherical regular pentagons and twenty vertexes 31. Therefore, when each groove is formed about each vertex 31 and consequently, six or twenty grooves are formed along the circular paths 39 such that they are connected to one another.
• the area ratio of the grooves relative to the surface area of the golf ball may be too small to reduce an air resistance acting on the golf ball down to a desired level, or may be too large to improve the directionality of putting.
• each groove can be changed into a variety of different shapes other than the above described shapes, so long as all the grooves maintain a net shape and fulfill the symmetry of a spherical surface, and the surface area of the grooves occupies 14 to 69 % of the surface area of the golf ball.
• the sphere 10 has a divisional composition of a spherical polyhedron, and grooves are formed along edges 41 of the spherical polyhedron.
• the spherical polyhedron may be a spherical regular icosahedron, or may be a spherical icosahedron consisting of eight spherical regular pentagons and twelve spherical regular hexagons as shown in FIG. 6.
• the present invention is applicable in such a manner that grooves are formed along the edges 41 of the spherical polyhedron.
• the grooves, formed along the edges 41 of the spherical polyhedron, may be connected to or separated from one another.
• FIG. 7 illustrating laboratory equipment used in an experiment of the present invention
• an experimental model of a golf ball was installed in a wind tunnel, to measure an air resistance acting on the experimental model while increasing the velocity of wind from 5m/s to 30m/s by lm/s.
• the golf ball and the experimental model also have the same air resistance coefficient as each other. Accordingly, an air resistance actually acting on the golf ball could be calculated based on experimental values.
• a regular hexahedron is inscribed in the model such that the model has a divisional composition of a spherical regular hexahedron.
• a circular path 35a is defined about one vertex 31a of a spherical square constituting the spherical regular hexahedron by connecting three vertexes (only two vertexes 31b and 31c are visible from FIG. 8) closest to the vertex 31a to one another.
• the included angle ⁇ is approximately 70 degrees.
• circular paths 35b to 35h thereof can be defined, and grooves can be formed along all the circular paths 35a to 35h.
• grooves can be additionally formed along shorter diagonal lines 42a, 42b, 42c, 42d, ... of some cells containing the edges 41 of the spherical regular hexahedron.
• the diameter of the model was 150 mm.
• the outer surface of the model was formed with grooves having a width of 5 mm and a depth of 0.5 mm.
• protrusions having a height of 0.5 mm were additionally formed in the grooves.
• the protrusions were partially cut and removed at intervals as shown in FIG. 9.
• FIG. 10 is a graph illustrating the relationship between the Reynolds number and the air resistance coefficient
• FIG. 11 is a graph illustrating the relationship between the velocity of a golf ball and the air resistance.
• an air resistance acting on the grooved golf ball begins to be smaller than that acting on the dimpled golf ball from the critical point where the Reynolds number is approximately 190,000 (the velocity of the golf ball is 240 km/hr). Since the initial velocity of a drive shot is 190 to 300 km/hr, the overall air resistance acting on the grooved golf ball is larger than that acting on the dimpled golf ball, thus suffering from a reduction of a carry distance and consequently, being unsuitable for use as a golf ball.
• the air resistance acting on the grooved golf ball exceeds that acting on the dimpled golf ball, resulting in a reduced carry distance of the golf ball. Therefore, in this case, it is preferable that the number of the grooves, having the width of 2 mm or less, be increased as compared to that of Example 1, so as to increase the area ratio of the grooves relative to the surface area of the golf ball, for the sake of reducing the air resistance acting on the golf ball.
• Example 2 in which protrusions are formed in the grooves, it is seen from FIGS. 10 and 11 that the air resistance acting on the grooved golf ball is smaller than that acting on the dimpled golf ball except for a region where the Reynolds number is 50,000(80 km/hr) to 110,000(140 km/hr).
• the area ratio of the grooves relative to the surface area of the grooved golf ball is only approximately 23%. Therefore, the grooved golf ball of Example 2 could achieve a remarkable reduction in the occurrence of putting errors due to the curvature of the grooves, thus enabling accurate putting of the golf ball.
• Example 3 has the same experimental conditions as those of Example 2 except for the fact that the protrusions formed in the grooves are partially cut and removed at intervals, rather than being continuously connected to one another. Similar to Example 2, the air resistance acting on the golf ball of Example 3 is smaller than that acting on the dimpled golf ball.
• Example 5 In the experiment of the present invention, also, other models having a diameter of 150 mm are considered.
• the outer surface of the model is formed with grooves having a width of 10 mm and a depth of 1 mm.
• Example 5 continuous protrusions having a height of 1 mm are formed in the grooves as shown in FIG. 12.
• FIG. 13 is a graph illustrating the relationship between the Reynolds number and the air resistance coefficient
• FIG. 14 is a graph illustrating the relationship between the velocity of a golf ball and the air resistance.
• Examples 4 and 5 show the air resistances acting on the grooved golf ball similar to that acting on the dimpled golf ball, it could be appreciated that the area ratios of grooves relative to the surface area of the respective golf balls of Examples 4 and 5 are only approximately 46%, thereby enabling accurate putting of the golf ball as compared to the dimpled golf ball.
• the groove 20 When no protrusions are formed in the grooves, it is preferable that the groove 20 have a width W below 4 mm and a depth GH of 0.1 to 0.4 mm in consideration of the air resistance acting on the golf ball and the accurate directionality of putting. If the depth GH of the groove 20 is smaller than 0.1 mm, RPM of the backspin of the grooved golf ball decreases as compared to that of the dimpled golf ball, thus resulting in a reduced lift force.
• the width W of the groove 20 is preferably 1 to 5 mm, and the depth GH of the groove 20 is preferably 0.1 to 0.5 mm. Also, in consideration of the accurate directionality of putting, the height H of the protrusion 21 is preferably smaller than the depth GH of the groove 20. Similar to the grooves 20, the protrusion 21 may be connected to or separated from other protrusions.
• width W and the depth GH of the groove 20 and the height H of the protrusion 21, formed in the surface of the sphere 10, may be changed per their locations such that a variety of different sizes of grooves 20 or protrusions 21 exist together in the single sphere 10.
• a golf ball has net-shaped grooves formed throughout a sphere.
• an air resistance acting on the golf ball is similar to or smaller than that acting on a dimpled golf ball, thus resulting in an improvement in the carry distance of the golf ball.

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• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Physical Education & Sports Medicine (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)

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• 2007
  • 2007-02-22 KR KR1020070017963A patent/KR100803528B1/ko active IP Right Grant
• 2008
  • 2008-02-20 US US12/449,731 patent/US20120270683A1/en not_active Abandoned
  • 2008-02-20 WO PCT/KR2008/000985 patent/WO2008102977A2/en active Application Filing
  • 2008-02-20 EP EP08723023.1A patent/EP2112948B1/de active Active

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