JP6848423B2 - Golf ball - Google Patents

Description

The present invention relates to a golf ball in which a large number of dimples are formed on the ball surface, and more specifically, to a golf ball in which aerodynamic performance is improved by optimizing the cross-sectional shape of the dimples formed on the ball surface.

In order to improve the flight distance of a golf ball, it is important to increase the resilience of the ball and to reduce the air resistance during flight by the dimples formed on the surface of the ball to improve the aerodynamic performance. This is generally well known, and for example, a golf ball having a large number of dimples having an arcuate cross section as shown in FIG. 5 is used by many golfers. Further, in order to further improve the aerodynamic performance of the ball, for example, Japanese Patent Application Laid-Open No. 11-57065, Japanese Patent Application Laid-Open No. 2005-342407, Japanese Patent Application Laid-Open No. 2006-149929, Japanese Patent Application Laid-Open No. 2006-158778. , Japanese Patent Application Laid-Open No. 2006-187476, Japanese Patent Application Laid-Open No. 2006-187485, Japanese Patent Application Laid-Open No. 2008-93481, and the like have made various proposals regarding the shape and arrangement method of dimples.

Further, in U.S. Pat. Nos. 8,888,613 and 8974320, when determining the cross-sectional shape of a dimple, the inside thereof is divided into a plurality of specific regions, and the average depth in each region is defined as a specific relationship. A golf ball has been proposed in which a peculiar cross-sectional curved shape can be obtained by quantifying the ball so as to satisfy the above. However, even with these techniques, it cannot be said that the flight distance of a golf ball is sufficiently improved, and there is still room for improvement in the aerodynamic performance and flight performance of the ball. Further, there have not been many golf balls having a large number of dimples having a peculiar cross-sectional curved shape as described above.

It is important to develop a golf ball that can provide a satisfactory flight performance to more golfers in order to broaden the base of golfers, and further improve the aerodynamic performance of the ball in order to obtain better flight performance. Is indispensable.

Japanese Unexamined Patent Publication No. 11-57065 Japanese Unexamined Patent Publication No. 2005-342407 Japanese Unexamined Patent Publication No. 2006-149929 Japanese Unexamined Patent Publication No. 2006-158778 Japanese Unexamined Patent Publication No. 2006-187476 Japanese Unexamined Patent Publication No. 2006-187485 Japanese Unexamined Patent Publication No. 2008-93481 U.S. Pat. No. 8,888,613 U.S. Pat. No. 8,974,320

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a golf ball capable of further improving the aerodynamic performance of the ball and improving the flying performance.

As a result of diligent studies to achieve the above object, the present inventors have made an arbitrary one dimple edge and a virtual plane formed by the peripheral edge of the dimple from the deepest point of the dimple when determining the cross-sectional shape of the dimple. The straight line passing through the vertical line foot (hanging foot) is set as the reference line, and in the line segment from the dimple edge to the vertical foot, the dimple edge is set to 0% (base point) and the vertical line foot is set as the reference line. By dividing the line segment every 20% as 100% along the dimple depth and setting the amount of change ΔH of the dimple depth in the dimple region divided every 20% within a certain range, the cross-sectional shape of the dimple can be changed. It has been found that it is effective for stabilizing the effect of dimples during flight of a ball and improving aerodynamic performance, and has led to the present invention.

That is, it is indispensable to improve the aerodynamic performance of the ball in order to secure the flight. In the present invention, by further optimizing the cross-sectional shape of the dimples, the variation in flight is reduced, the aerodynamic performance is improved, and the rate of change in depth at a certain position in the dimples is kept within a certain range. As a result, the effect of the dimples can be stabilized and the aerodynamic performance can be improved.

Therefore, the present invention provides the following golf balls.
[1] A golf ball having a large number of dimples on its surface, which is presented by a curved line or a combination of a straight line and a curved line, and has a cross-sectional shape specified by the procedures (i) to (iv) below (specification). A golf ball characterized in that at least one dimple having a cross-sectional shape is arranged and the total number of dimples is 250 to 380.
(I) The dimple center is the foot (foot drop) of the perpendicular line drawn from the deepest point of the dimple to the virtual plane created at the periphery of the dimple, and the straight line passing through the dimple center and any one dimple edge is used as the reference line. To do.
(Ii) Of the reference line, the line segment from the dimple edge to the dimple center is divided into 100 points or more, and when the distance from the dimple edge to the dimple center is set to 100%, the distance between each point. Calculate the ratio of.
(Iii) The ratio of the dimple depth in every 20% of 0 to 100% of the distance from the dimple edge to the dimple center is calculated.
(Iv) At the ratio of the depth in the dimple region of 20 to 100% of the distance from the dimple edge to the dimple center, the amount of change ΔH of the depth every 20% of the distance is obtained, and this amount of change ΔH is the above. The cross-sectional shape of the dimples is designed so that it is 10% or more and 24% or less in all the regions corresponding to the distance of 20 to 100%.
[2] The golf ball according to [1], wherein the change amount ΔH of the ratio of the dimple depth at a distance of 20% from the dimple edge is maximum in the dimple having the specific cross-sectional shape.
[3] The golf ball according to [1] or [2], wherein the dimples having the specific cross-sectional shape are 60% or more of the total number of dimples.
[4] The golf ball according to any one of [1] to [3], wherein the dimples formed on the surface of the ball consist of two or more types having different diameters and / or depths.
[5] The golf ball according to any one of [1] to [4], wherein the curve exhibiting the cross-sectional shape of the dimple having the specific cross-sectional shape includes two or more inflection points.

According to the golf ball of the present invention, by having a peculiar cross-sectional shape of dimples, the cross-sectional shape stabilizes the effect of the dimples during flight of the ball, and the aerodynamic performance can be further improved.

FIG. 1 (A) is a plan view showing the appearance of a golf ball according to an embodiment of the present invention, and FIG. 1 (B) is formed on the surface of the golf ball shown in FIG. 1 (A). It is an enlarged sectional view which enlarged one of the dimples. FIG. 2 is an explanatory diagram showing the relationship between the cross section of the dimple and the area set inside the dimple. FIG. 3A is a plan view showing the appearance of a golf ball according to another embodiment of the present invention, and FIG. 3B is formed on the surface of the golf ball shown in FIG. 3A. It is an enlarged sectional view which enlarged one of the dimples. FIG. 4A is a plan view showing the appearance of a conventional golf ball on which double dimples are formed, and FIG. 4B is formed on the surface of the golf ball shown in FIG. 4A. It is an enlarged sectional view which enlarged one of the dimples. FIG. 5 (A) is a plan view showing the appearance of a golf ball having dimples having a conventional arc-shaped cross-sectional shape, and FIG. 5 (B) is a plan view of the golf ball shown in FIG. 5 (A). It is an enlarged sectional view of one of the dimples formed on the surface of. FIG. 6 is a schematic cross-sectional view showing an example of the structure of the golf ball of the present invention.

Hereinafter, the golf ball of the present invention will be described in detail with reference to the drawings.
FIG. 1 (A) is a plan view showing the appearance of a golf ball according to an embodiment of the present invention, and FIG. 1 (B) is formed on the surface of the golf ball shown in FIG. 1 (A). It is an enlarged sectional view which enlarged one of the dimples. In the figure, reference numeral D indicates a dimple, E and E indicate a dimple edge, P indicates the deepest point of the dimple, a straight line L indicates a reference line passing through the dimple edge E and the dimple center O, and a two-dot chain line indicates a virtual spherical surface. The foot of the perpendicular line drawn from the deepest point P of the dimple D to the virtual plane formed at the periphery of the dimple D (hereinafter referred to as the foot drop) coincides with the dimple center O. The dimple edges E and E are boundaries between the dimple D and the region (land portion) where the dimple D is not formed on the ball surface, and correspond to the point where the virtual spherical surface comes into contact with the ball surface (hereinafter, the same applies). .. Further, the dimple D shown in FIG. 1 is a circular dimple in a plan view, and the center O of the dimple and the deepest point P coincide with each other in a plan view.

The cross-sectional shape of the dimples shown in FIG. 1B gives priority to the understanding of the present invention and is not drawn according to the scale. This also applies to the cross-sectional shapes of the dimples shown in FIGS. 2, 3 (B), 4 (B), and 5 (B), which will be described later.

In the present invention, the cross-sectional shape of the dimple D needs to satisfy the following conditions. The conditions will be described below.

First, as the condition (i), the foot (foot drop) of the perpendicular line drawn from the deepest point P of the dimple to the virtual plane created at the periphery of the dimple is set as the dimple center O, and the dimple center O and any one dimple. The straight line passing through the edge E is defined as the reference line L.

Next, as the condition of (ii), the line segment from the dimple edge E to the dimple center O in the reference line L is divided into 100 points or more. Then, when the distance from the dimple edge to the dimple center is set to 100%, the ratio of the distances at each point is calculated. That is, as shown in FIG. 2, the wavy line in the figure is a dividing line represented along the depth of the dimples. The dimple edge E is a base point and is at a position of 0% on the reference line, and the dimple center O is at a position of 100% with respect to the line segment EO on the reference line.

Next, as the condition of (iii), the ratio of the dimple depth in every 20% of 0 to 100% of the distance from the dimple edge E to the dimple center O is calculated. In this case, the dimple center O is the deepest part P of the dimples and has a depth H (mm). With this as 100% of the depth, the ratio of the dimple depth at each distance is calculated. The ratio of the dimple depth at the dimple edge E is 0%.

Then, as the condition (iv), the amount of change ΔH of the depth every 20% of the distance is obtained at the ratio of the depth in the dimple region of 20 to 100% of the distance from the dimple edge to the dimple center. The cross-sectional shape of the dimples is designed so that the amount of change ΔH is 6% or more and 24% or less in all the regions of the distance 20 to 100%.

In the present invention, by quantifying the cross-sectional shape of the dimples in this way, that is, by setting the value of the change amount ΔH of the dimple depth to 6% or more and 24% or less, the dimples can be skipped by optimizing the cross-sectional shape. The variation is reduced and the aerodynamic performance is improved. The preferred value of the above change amount ΔH is 8 to 22%, more preferably 10 to 20%.

Further, in the present invention, from the viewpoint of further enhancing the effect of the present invention, it is preferable that the amount of change ΔH of the ratio of the dimple depth at a distance of 20% from the dimple edge is maximized in the dimple having the specific cross-sectional shape. Is. Further, it is also suitably adopted that the curve exhibiting the cross-sectional shape of the dimple having the specific cross-sectional shape includes two or more inflection points from the viewpoint of enhancing the effect of the present invention.

In FIG. 1, a circular dimple in a plan view has been described as an example, but the shape (plan view shape) is not limited to a circle, and may be appropriately selected from a polygonal shape, a teardrop shape, an elliptical shape, and the like. Can be done. The cross-sectional shape of the dimples having a shape other than the circular shape can be set by the same method as described above. Further, in the example shown in FIG. 1, the center O of the dimple and the deepest point P coincide with each other, but the deepest point P does not necessarily have to coincide with the center O of the dimple. Even when the center O of the dimple D and the deepest point P do not match, no particular problem occurs, and the amount of change ΔH in the dimple depth in the dimple region divided every 20% is obtained in the same manner as described above. Can be done.

Further, regarding the cross section of the dimple D, in FIG. 1, a gentle curve is mainly used and a shape including a straight line is shown, but the shape is not limited to this, and is presented by a curved line or a combination of a straight line and a curved line. Anything within the scope of the present invention will do.

The diameter of the dimple D (diagonal length in the case of a polygon) is not particularly limited, but is preferably 1.5 mm or more, and more preferably 2.0 mm or more. Further, the upper limit thereof is not particularly limited, but is preferably 7.0 mm or less, and more preferably 6.0 mm or less.

The depth H at the deepest point P of the dimple D is not particularly limited, but is preferably 0.05 to 0.5 mm, and more preferably 0.1 to 0.4 mm.

The method of arranging the dimples is not particularly limited, but a method using a geometrical arrangement pattern of regular polyhedrons such as a regular octahedron, a regular 12-sided body, and a regular 20-sided body, a 3-fold symmetry, and a 4-fold symmetry. A method of arranging the balls so as to be rotationally symmetric with respect to the pole points of the balls, such as 5-fold symmetry and 6-fold symmetry, can be preferably adopted.

The total number of dimples formed on the surface of the ball is not particularly limited, but may be preferably 250 or more, more preferably 275 or more, and even more preferably 300 or more. Further, the upper limit thereof is not particularly limited, but may be preferably 380 or less, more preferably 370 or less, and further preferably 360 or less.

In the present invention, the dimples having the above-mentioned cross-sectional shape include at least one dimple formed on the ball surface, and are included in a part of the entire dimple. Therefore, in the present invention, not all the dimples formed on the ball surface need to be dimples having the above-mentioned cross-sectional shape, and conventional dimples may be mixed. In this case, the ratio of the dimples having the above cross-sectional shape to the total number of dimples formed on the ball surface is not particularly limited, but may be 20% or more, preferably 50% or more, more preferably. Can be 60% or more, more preferably 80% or more, and most preferably 100%.

In the present invention, although not particularly limited, it is preferable that two or more types of dimples having different diameters and / or depths are formed, and more preferably three or more types are formed. Even if dimples that do not satisfy the above conditions are included, if they contain dimples having different diameters and / or depths, they are treated as different types of dimples.

The ratio (dimple surface occupancy) SR value (%) occupied by the total area of the virtual sphere surrounded by the edges of the dimples is usually 70% or more, preferably 80% or more. If the SR value is out of the above range, an appropriate trajectory may not be obtained and the flight distance may decrease.

The ratio of the total volume of dimple space formed downward from the plane surrounded by the edges of the dimples to the volume of the virtual sphere assuming that there are no dimples on the ball surface (dimple space occupancy) VR is particularly limited. However, it can be usually 0.7% or more, preferably 0.75% or more, and more preferably 0.8% or more. The upper limit thereof is also not particularly limited, but may be 1.5% or less, preferably 1.45% or less, and more preferably 1.4% or less. By setting the dimple space occupancy rate VR in the above range, it is possible to prevent the hit ball from being blown up too much when the ball is hit by a club that gains a flight distance such as a driver, or to prevent the hit ball from rising and dropping.

3DCAD / CAM is used to manufacture the mold for molding the above golf ball, and a method of directly cutting the entire surface shape into the master mold for inversion in three dimensions and the cavity part of the molding mold (inside). It is possible to adopt a method of directly carving the wall surface) in three dimensions.

The surface of the ball can be coated with various coatings such as white enamel coating, epoxy coating and clear coating, in the same manner as a normal golf ball. In this case, it is desirable to apply the dimples evenly and evenly so as not to damage the cross-sectional shape of the dimples.

The golf ball of the present invention is not particularly limited in terms of internal structure, and may be a solid golf ball such as a one-piece golf ball, a two-piece golf ball, or a multi-piece golf ball having a three-layer structure or more, or a thread-wound golf ball. Can be applied to golf balls. In particular, it is preferable to use a multi-piece solid golf ball G in which one layer or two or more intermediate layers 2 are formed between the solid core 1 and the cover 3 as shown in FIG. Reference numeral D in FIG. 6 indicates dimples.

Further, although not particularly limited, in the golf ball G shown in FIG. 6, it is preferable that the solid core 1 is formed of polybutadiene as a main material. The amount of deflection from the state in which the initial load of 98 N (10 kgf) is applied to the solid core 1 to the time when the final load of 1,275 N (130 kgf) is applied is not particularly limited, but is 2.0 mm or more. can do. Further, the upper limit thereof is not particularly limited, but may be 6.0 mm or less.

On the other hand, the materials of the intermediate layer 2 and the cover 3 are not particularly limited, but for example, known ionomer resins, thermoplastic elastomers, thermosetting elastomers and the like can be preferably used. Examples of the thermoplastic elastomer include various thermoplastic elastomers such as polyester-based, polyamide-based, polyurethane-based, olefin-based, and styrene-based.

The material hardness of the intermediate layer is not particularly limited, but the shore D hardness can usually be 30 or more. Further, the upper limit thereof is not particularly limited, but the shore D hardness can usually be 75 or less.

The material hardness of the cover is not particularly limited, but the shore D hardness can usually be 30 or more. Further, the upper limit thereof is not particularly limited, but the shore D hardness can be 75 or less.

Here, the above-mentioned material hardness is the hardness measured by molding a material into a sheet having a thickness of 2 mm with a press machine, superimposing the material on a thickness of 6 mm or more, and measuring using a type D durometer according to ASTM D2240. ..

The thickness of the intermediate layer and the thickness of the cover are not particularly limited, but are preferably 0.3 to 3.0 mm. The weight, diameter, and the like of the ball can be appropriately set according to the Rules of Golf.

As described above, according to the golf ball of the present invention, the formation of dimples having a characteristic cross-sectional shape on the surface reduces air resistance during flight and improves aerodynamic performance. Since a higher trajectory can be obtained, the flight distance can be further increased.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 and 2, Comparative Examples 1 and 2]
On the surface of the ball, Example 1 (FIG. 1), Example 2 (FIG. 3), Comparative Example 1 (FIG. 4, conventional double dimples) and Comparative Example 2 (FIG. 5, conventional arc-shaped dimples in cross section). Golf balls with each dimple formed were produced and their flying characteristics were compared. Four types of dimples in each of the above examples were used, and the details are shown in Tables 1 to 4.

At this time, the depth of each dimple from the reference line L to the inner wall surface of each dimple is obtained at 100 points at equal intervals between the dimple edge E of the reference line L and the dimple center O, and is shown in Tables 1 to 4. did.

Next, the amount of change ΔH of the ratio of the dimple depth at every 20% of the distance from the dimple edge E of the reference line L was determined and shown in Tables 1 to 4.

The internal structure of the golf ball of each of the above examples is a three-layer structure including a core 1, an intermediate layer 2, and a cover 3, as shown in FIG. Details of each of these layers are as follows.

Core polybutadiene A (product name "BR51", manufactured by JSR) 80 parts by mass, polybutadiene B (product name "BR11", manufactured by JSR) 20 parts by mass, zinc acrylate 28.5 parts by mass, 1,1-di (product name "BR11", manufactured by JSR) Mix of t-butylperoxy) cyclohexane and silica (product name "Perhexa C-40", manufactured by Nichiyu Co., Ltd.) 1.2 parts by mass, zinc oxide 4 parts by mass, barium sulfate 300 (manufactured by Sakai Chemical Industry Co., Ltd.) 19 A rubber composition containing 1 part by mass, 0.1 part by mass of an antioxidant (product name "Nocrack NS-6", manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.), and 0.1 part by mass of pentachlorothiophenol zinc salt. Was prepared. Then, the obtained rubber composition was vulcanized and molded by a core mold under vulcanization conditions at 155 ° C. for 13 minutes to prepare a solid core having a diameter of 37.7 mm. The amount of deflection of the solid core obtained above from the state in which the initial load of 98 N (10 kgf) was applied to the time when the final load of 1,275 N (130 kgf) was applied was measured and found to be 3.6 mm.

Intermediate layer and cover Around the core obtained above, an intermediate layer with a thickness of 1.7 mm is formed by the injection molding method using the following intermediate layer material, and then the thickness is increased by the injection molding method using the following cover material. A cover having a diameter of 0.8 mm was formed to produce a three-piece solid golf ball having a diameter of 42.7 mm and a weight of 45.4 g. The dimples were formed on the surface of the cover at the same time as the cover was formed. The intermediate layer materials are Hymilan 1605 (ionomer resin manufactured by Mitsui DuPont Polychemical), Hymilan 1557 (ionomer resin manufactured by Mitsui DuPont Polychemical), Hymilan 1706 (ionomer resin manufactured by Mitsui DuPont Polychemical), It is a resin composition in which trimethylolpropane is blended in a ratio of 50/15/35 / 1.1 by mass. The cover materials are Pandex T-8295 (polyurethane-based thermoplastic elastomer manufactured by DIC Bayer Polymer), titanium oxide, sun wax 161P (polyethylene wax manufactured by Sanyo Kasei Co., Ltd.), and isocyanate compound (4,4'-diphenylmethane). A resin composition containing diisocyanate) at a ratio of 100 / 3.5 / 1 / 7.5 by mass. The material hardness of the intermediate layer material and the cover material was 62 and 47, respectively, in terms of shore D hardness.

A performance test driver (W # 1) was set on the striking robot, and the height and flight distance at the highest reaching point when striking the ball were measured. The striking conditions were set so that the initial velocity of the ball was about 65 m / s, the launch angle was about 10 °, and the initial backspin amount was about 3000 rpm. The club used "TourStage X-Drive 701" (loft 9 °) manufactured by Bridgestone Sports Co., Ltd. The measurement results are shown in Tables 1 to 4.

From the results of Tables 1 to 4, the carry of Examples 1 and 2 was increased in Examples 1 and 2 even though the trajectory height was the same as that of Comparative Examples 1 and 2 due to the difference in the cross-sectional shape of the dimples. .. As a result, the golf balls of Examples 1 and 2 had a significantly increased flight distance as compared with the golf balls of Comparative Examples 1 and 2.

Claims (5)

A golf ball having a large number of dimples on its surface, which is presented by a curved line or a combination of a straight line and a curved line, and has a cross-sectional shape specified by the procedures (i) to (iv) below (specific cross-sectional shape). A golf ball characterized in that at least one dimple) is arranged and the total number of dimples is 250 to 380.
(I) The dimple center is the foot (foot drop) of the perpendicular line drawn from the deepest point of the dimple to the virtual plane created at the periphery of the dimple, and the straight line passing through the dimple center and any one dimple edge is used as the reference line. To do.
(Ii) Of the reference line, the line segment from the dimple edge to the dimple center is divided into 100 points or more, and when the distance from the dimple edge to the dimple center is set to 100%, the distance between each point. Calculate the ratio of.
(Iii) The ratio of the dimple depth in every 20% of 0 to 100% of the distance from the dimple edge to the dimple center is calculated.
(Iv) At the ratio of the depth in the dimple region of 20 to 100% of the distance from the dimple edge to the dimple center, the amount of change ΔH of the depth every 20% of the distance is obtained, and this amount of change ΔH is the above. The cross-sectional shape of the dimples is designed so that it is 10% or more and 24% or less in all the regions corresponding to the distance of 20 to 100%. The golf ball according to claim 1, wherein in the dimple having the specific cross-sectional shape, the amount of change ΔH of the ratio of the dimple depth at a distance of 20% from the dimple edge is maximum. The golf ball according to claim 1 or 2, wherein the dimples having the specific cross-sectional shape are 60% or more of the total number of dimples. The golf ball according to any one of claims 1 to 3, wherein the dimples formed on the surface of the ball consist of two or more types having different diameters and / or depths. The golf ball according to any one of claims 1 to 4, wherein the curve exhibiting the cross-sectional shape of the dimple having the specific cross-sectional shape includes two or more inflection points.

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