GOLF BALL

CROSS REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to Japanese patent application JP 2022-013356, filed on Jan. 31, 2022, the entire contents of which is incorporated herein by reference in its entirety.

BACKGROUND
Technical Field

The present disclosure relates to a golf ball having a relatively large number of dimples on the surface thereof.

Background Art

Golf balls can have dimples on the surfaces thereof. The dimples disturb the air flow around the golf ball during flight to cause turbulent flow separation. This phenomenon is referred to as “turbulization.” Due to turbulization, separation points of the air from the golf ball shift backwards leading to a reduction of drag. The turbulization promotes the displacement between the separation point on the upper side and the separation point on the lower side of the golf ball, which results from the backspin, thereby enhancing the lift force that acts upon the golf ball. The reduction of drag and the enhancement of lift force are referred to as a “dimple effect”. Excellent dimples efficiently disturb the air flow. Excellent dimples produce a large flight distance.

An interest to golf players concerning golf balls is flight performance. Golf players may prefer a golf ball with which a flight distance is large when the golf ball is hit with a driver (W#1). Japanese Laid-Open Patent Publication No. 2014-140638 describes a golf ball with which a large flight distance can be achieved upon a shot with a driver.

Golf players frequently use fairway woods for second shots on long-distance holes. Typical fairway woods are a spoon (W#3) and a baffy (W#4). Golf players are also interested in a flight distance upon hitting with a fairway wood.

SUMMARY

A golf ball according to an aspect can have a plurality of dimples on a surface thereof. A trajectory calculated using a drag coefficient CD and a lift force coefficient CL obtained in an indoor test range which is a rule set by the United States Golf Association, on the basis of a model proposed by S. J. Quintavalla of the United States Golf Association and disclosed in “Science and Golf IV, Chapter 30, A Generally Applicable Model for the Aerodynamic Behavior of Golf Balls” published in 2002, by a program created in accordance with a manual provided by the United States Golf Association, under conditions of an initial speed of 260 ft/s, a launch angle of 15.0 degrees, and an initial backspin rate of 3000 rpm, satisfies the following mathematical formula,

Amin≥−5.0*Vave−38.98,

wherein A min represents a minimum value (degree) of a vector angle A in the trajectory, and Vave represents an average volume (mm³) of the dimples. The vector angle A is calculated by the following mathematical formula,

A=ATAN(Vy/Vx),

wherein Vx represents a horizontal component of a speed of the golf ball, and Vy represents a vertical component of the speed of the golf ball.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing a golf ball according to an embodiment of the present disclosure;

FIG. 2 is an enlarged plan view showing the golf ball in FIG. 1;

FIG. 3 is a front view showing the golf ball in FIG. 2 with annotations;

FIG. 4 is an enlarged cross-sectional view showing a part of the golf ball in FIG. 1;

FIG. 5 is a graph showing a relationship between an average volume of dimples and a minimum vector angle of the golf ball in FIG. 1;

FIG. 6 is a plan view showing a golf ball of Example 3 described herein; and

FIG. 7 is a front view showing the golf ball in FIG. 6 with annotations.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments will be described in detail with appropriate reference to the drawings.

A golf ball 2 shown in FIG. 1 can include a spherical core 4 and a cover 6 positioned outside the core 4. The golf ball 2 can have a relatively large number of dimples 8 on the surface thereof. Of the surface of the golf ball 2, a part other than the dimples 8 is a land 10. The golf ball 2 can include a paint layer and a mark layer on the external side of the cover 6. The golf ball 2 may have one or more mid layers between the core 4 and the cover 6.

The golf ball 2 can have a diameter of not less than 40 mm and not greater than 45 mm, as an example. From the viewpoint of conformity to the rules established by the United States Golf Association (USGA), the diameter can be not less than 42.67 mm. From the viewpoint of suppression of air resistance, the diameter can be not greater than 44 mm, for instance, not greater than 42.80 mm.

The golf ball 2 can have a mass of not less than 40 g and not greater than 50 g, as an example. From the viewpoint of attainment of great inertia, the mass can be not less than 44 g, for instance, not less than 45.00 g. From the viewpoint of conformity to the rules established by the USGA, the mass can be not greater than 45.93 g.

The core 4 can be formed by crosslinking a rubber composition. Examples of the base rubber of the rubber composition include polybutadienes, polyisoprenes, styrene-butadiene copolymers, ethylene-propylene-diene copolymers, and natural rubbers. Two or more rubbers may be used in combination. From the viewpoint of resilience performance, polybutadienes may be preferable, and high-cis polybutadienes may be particularly preferable.

The rubber composition of the core 4 can include a co-crosslinking agent. Preferable co-crosslinking agents from the viewpoint of resilience performance can include zinc acrylate, magnesium acrylate, zinc methacrylate, and magnesium methacrylate. The rubber composition can include an organic peroxide together with a co-crosslinking agent. Examples of preferable organic peroxides include dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and di-t-butyl peroxide.

The rubber composition of the core 4 may include additives such as a filler, sulfur, a vulcanization accelerator, a sulfur compound, an anti-aging agent, a coloring agent, a plasticizer, and/or a dispersant. The rubber composition may include a carboxylic acid or a carboxylate. The rubber composition may include synthetic resin powder or crosslinked rubber powder.

The core 4 can have a diameter of not less than 30.0 mm, for instance, not less than 37.0 mm, such as not less than 38.0 mm. The diameter of the core 4 can be not greater than 42.0 mm, for instance, not greater than 41.5 mm, such as not greater than 41.0 mm.

The core 4 may have two or more layers. The core 4 may have a rib on the surface thereof. The core 4 may be hollow.

The cover 6 can be formed from a resin composition. Abase polymer for the resin composition can be an ionomer resin. Examples of ionomer resins include binary copolymers formed with an α-olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms. Examples of other ionomer resins include ternary copolymers formed with: an α-olefin; an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms; and an α, β-unsaturated carboxylate ester having 2 to 22 carbon atoms. For the binary copolymers and the ternary copolymers, α-olefins can be ethylene and propylene, and α, β-unsaturated carboxylic acids can be acrylic acid and methacrylic acid. In the binary copolymers and the ternary copolymers, some of the carboxyl groups are neutralized with metal ions. Examples of metal ions for neutralization include sodium ions, potassium ions, lithium ions, zinc ions, calcium ions, magnesium ions, aluminum ions, and neodymium ions.

The resin composition of the cover 6 may include another polymer instead of or together with an ionomer resin. Examples of the other polymer include polyurethanes, polystyrenes, polyamides, polyesters, and polyolefins. The resin composition may include two or more polymers.

The resin composition of the cover 6 may include a coloring agent such as titanium dioxide, a filler such as barium sulfate, a dispersant, and antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent material, a fluorescent brightener, etc. For the purpose of specific gravity adjustment, the resin composition may include powder of a metal with a high specific gravity such as tungsten and molybdenum.

The cover 6 can have a thickness of not less than 0.3 mm, for instance, not less than 1.0 mm, such as not less than 1.5 mm. The thickness of the cover 6 can be not greater than 2.5 mm, for instance, not greater than 2.2 mm, such as not greater than 2.0 mm. The cover 6 can have a specific gravity of not less than 0.90 and not greater than 1.10, as an example. The cover 6 may have two or more layers.

As shown in FIGS. 2 and 3, the contour of each dimple 8 can be circular. The golf ball 2 can have dimples A each having a diameter of 4.40 mm, for instance; dimples B each having a diameter of 4.30 mm, for instance; dimples C each having a diameter of 4.15 mm, for instance; dimples D each having a diameter of 3.75 mm, for instance; and dimples E each having a diameter of 3.00 mm, for instance. The number of types of the dimples 8 can be five.

The number of the dimples A can be 76, for instance; the number of the dimples B can be 158, for instance; the number of the dimples C can be 76, for instance; the number of the dimples D can be 16, for instance; and the number of the dimples E can be 8, for instance. The total number N of the dimples 8 can be 334, for instance. A dimple pattern can be formed by these dimples 8 and the land 10.

FIG. 4 shows a cross section of the golf ball 2 along a plane passing through the central point of the dimple 8 and the central point of the golf ball 2. In FIG. 4, the up-down direction is the depth direction of the dimple 8. In FIG. 4, a chain double-dashed line 12 indicates a phantom sphere. The surface of the phantom sphere 12 is the surface of the golf ball 2 when it is postulated that no dimple 8 exists. The diameter of the phantom sphere 12 is equal to the diameter of the golf ball 2. The dimple 8 is recessed from the surface of the phantom sphere 12. The land 10 coincides with the surface of the phantom sphere 12. In the present embodiment, the cross-sectional shape of each dimple 8 is substantially a circular arc. The curvature radius of this circular arc is shown by reference character CR in FIG. 4.

In FIG. 4, an arrow Dm indicates the diameter of the dimple 8. The diameter Dm is the distance between two tangent points Ed appearing on a tangent line Tg that is drawn tangent to the opposite ends of the dimple 8. Each tangent point Ed is also the edge of the dimple 8. The edge Ed defines the contour of the dimple 8.

The diameter Dm of each dimple 8 can be not less than 2.0 mm and not greater than 6.0 mm, for instance. The dimple 8 having a diameter Dm of not less than 2.0 mm can contribute to turbulization. From this viewpoint, the diameter Dm can be not less than 2.5 mm, for instance, not less than 2.8 mm. The dimple 8 having a diameter Dm of not greater than 6.0 mm does not impair a fundamental feature of the golf ball 2 being substantially a sphere. From this viewpoint, the diameter Dm can be not greater than 5.5 mm, for instance, not greater than 5.0 mm.

In FIG. 4, a double headed arrow Dp1 indicates a first depth of the dimple 8. The first depth Dp1 is the distance between the deepest part of the dimple 8 and the surface of the phantom sphere 12. In FIG. 4, a double headed arrow Dp2 indicates a second depth of the dimple 8. The second depth Dp2 is the distance between the deepest part of the dimple 8 and the tangent line Tg.

From the viewpoint of suppression of rising of the golf ball 2 during flight, the first depth Dp1 of each dimple 8 can be not less than 0.10 mm, for instance, not less than 0.13 mm, such as not less than 0.15 mm. From the viewpoint of suppression of dropping of the golf ball 2 during flight, the first depth Dp1 can be not greater than 0.65 mm, for instance, not greater than 0.60 mm, such as not greater than 0.55 mm.

The area S of the dimple 8 is the area of a region surrounded by the contour line of the dimple 8 when the central point of the golf ball 2 is viewed at infinity. In the case of a circular dimple 8, the area S can be calculated by the following mathematical formula.

S=(Dm/2)²*π

In the golf ball 2 shown in FIGS. 2 and 3, the area of each dimple A can be 15.21 mm², for instance; the area of each dimple B can be 14.52 mm², for instance; the area of each dimple C can be 13.53 mm², for instance; the area of each dimple D can be 11.04 mm², for instance; and the area of each dimple E can be 7.07 mm², for instance.

In the present specification, the ratio of the sum of the areas S of all the dimples 8 relative to the surface area of the phantom sphere 12 can be referred to or regarded as an occupation ratio So. From the viewpoint of achieving sufficient turbulization, the occupation ratio So can be not less than 78%, for instance, not less than 80%, such as not less than 82%. The occupation ratio So can be not greater than 95%, for instance. In the golf ball 2 shown in FIGS. 2 and 3, the total area of the dimples 8 can be 4711.4 mm², for instance. The surface area of the phantom sphere 12 of the golf ball 2 can be 5728.0 mm², so that the occupation ratio So is 82.3%.

From the viewpoint that an appropriate trajectory can be achieved upon a shot with a fairway wood, the total number N of the dimples 8 can be not less than 250 and not greater than 450, for instance. The total number N can be not less than 270, for instance, not less than 280. The total number N can be not greater than 410, for instance, not greater than 380.

In the present disclosure, the “volume V of the dimple” can mean or be regarded as the volume of a portion surrounded by the surface of the phantom sphere 12 and the surface of the dimple 8. The total volume TV of the dimples 8 can be not less than 450 mm³and not greater than 750 mm³, for instance. With the golf ball 2 in which the total volume TV is not less than 450 mm³, for instance, rising of the golf ball 2 during flight can be suppressed. From this viewpoint, the total volume TV can be not less than 480 mm³, for instance, not less than 500 mm³. With the golf ball 2 in which the total volume TV is not greater than 750 mm³, for instance, dropping of the golf ball 2 during flight can be suppressed. From this viewpoint, the total volume TV can be not greater than 700 mm³, for instance, not greater than 670 mm³.

In the present specification, an average volume Vave (mm³) of the dimples 8 can be calculated by the following mathematical formula.

Vave=TV/N

From the viewpoint that an appropriate trajectory can be achieved upon a shot with a fairway wood, the average volume Vave can be not less than 1.40 mm³and not greater than 2.10 mm³, for instance. The average volume Vave can be not less than 1.50 mm³, for instance, not less than 1.55 mm³. The average volume Vave can be not greater than 2.00 mm³, for instance, not greater than 1.95 mm³.

In the golf ball 2 shown in FIGS. 2 and 3, the volume of each dimple A can be 2.075 mm³, for instance; the volume of each dimple B can be 1.945 mm³, for instance; the volume of each dimple C can be 1.761 mm³, for instance; the volume of each dimple D can be 1.335 mm³, for instance; and the volume of each dimple E can be 0.750 mm³, for instance. Therefore, the total volume TV of the dimples 8 can be 626.1 mm³, for instance. Since the total number N of the dimples 8 of the golf ball 2 can be 334, the average volume Vave can be 1.87 mm³, for instance.

In the present specification, a drag coefficient CD and a lift force coefficient CL of the golf ball 2 can be measured under 15 conditions specified in an indoor test range (ITR) which is a rule set by the United States Golf Association (USGA). A trajectory of the golf ball 2 can be calculated, using these drag coefficient CD and lift force coefficient CL, by a program created in accordance with a manual provided by the USGA. The following conditions can also be inputted to the program.

- Initial ball speed: 260 ft/s (260 feet per second)
- Launch angle: 15.0 degrees
- Initial backspin rate: 3000 rpm
  
  In this program, a trajectory can be calculated based on a model proposed by “S. J. Quintavalla” of the USGA. This model is disclosed in “Science and Golf IV, Chapter 30, A Generally Applicable Model for the Aerodynamic Behavior of Golf Balls” published in 2002.

By calculating the trajectory, a horizontal component Vx of the speed of the golf ball 2 and a vertical component Vy of the speed of the golf ball 2 can be calculated per 0.1 seconds from a launch point to a landing point. A vector angle A can be calculated from the horizontal component Vx and the vertical component Vy by the following mathematical formula.

A=ATAN(Vy/Vx)

In other words, the vector angle A can be calculated by an inverse tangent function of a ratio (Vy/Vx). The vector angle A (degree) can be obtained per 0.1 seconds from the launch point to the landing point by this calculation. For example, for a trajectory having a flight duration of 5.5 seconds, 55 vector angles A can be obtained.

In the present disclosure, the minimum value among a plurality of vector angles A from a launch point to a landing point can be referred to or regarded as minimum vector angle A min (degree). According to the finding by the present inventors, the minimum vector angle A min can influence a trajectory upon a shot with a fairway wood. From the viewpoint that an appropriate trajectory can be achieved upon a shot with a fairway wood, the minimum vector angle A min can be not less than −50.0 degrees and not greater than −46.0 degrees, for instance. The minimum vector angle A min can be not less than −49.5 degrees, for instance, not less than −49.0 degrees. The minimum vector angle A min can be preferably not greater than −46.5 degrees, for instance, not greater than −47.0 degrees.

FIG. 5 is a graph showing a relationship between the average volume Vave of the dimples 8 and the minimum vector angle A min. In FIG. 5, a point indicated by reference character P1 is a plot of the golf ball 2 shown in FIGS. 1 to 4.

In FIG. 5, a straight line indicated by reference character L1 can be represented by the following mathematical formula.

Amin=−5.0*Vave−38.98

As shown in FIG. 5, the point P1 is located above the straight line L1. In other words, the golf ball 2 can satisfy the following mathematical formula (1).

Amin≥−5.0*Vav−38.98 (1)

In the golf ball 2, the volume V of each dimple 8 can be sufficiently large, and the minimum vector angle A min can be relatively large. According to the finding by the present inventors, a trajectory obtained when the golf ball 2 that satisfies the mathematical formula (1) is hit with a fairway wood can be appropriate. The golf ball 2 can have excellent flight performance upon a shot with a fairway wood.

In FIG. 5, a straight line indicated by reference character L2 can be represented by the following mathematical formula.

Amin=−5.0*Vave−38.85

As shown in FIG. 5, the point P1 is located above the straight line L2. In other words, the golf ball 2 can satisfy the following mathematical formula (2).

Amin≥−5.0*Vave−38.85 (2)

In the golf ball 2, the volume V of each dimple 8 can be sufficiently large, and the minimum vector angle A min can be relatively large. According to the finding by the present inventors, a trajectory obtained when the golf ball 2 that satisfies the mathematical formula (2) is hit with a fairway wood can be appropriate. The golf ball 2 can have excellent flight performance upon a shot with a fairway wood.

In FIG. 5, a straight line indicated by reference character L3 can be represented by the following mathematical formula.

Amin=−5.0*Vave−38.40

As shown in FIG. 5, the point P1 is located on the straight line L3. In other words, the golf ball 2 can satisfy the following mathematical formula (3).

Amin≥−5.0*Vave−38.40 (3)

In the golf ball 2, the volume V of each dimple 8 can be sufficiently large, and the minimum vector angle A min can be relatively large. According to the finding by the present inventors, a trajectory obtained when the golf ball 2 that satisfies the mathematical formula (3) is hit with a fairway wood can be appropriate. The golf ball 2 can have excellent flight performance upon a shot with a fairway wood.

For the golf ball 2 on the straight line L1, a value (A min+5.0*Vave) can be −38.98, as an example. For the golf ball 2 on the straight line L2, the value (A min+5.0*Vave) can be −38.85, as an example. For the golf ball 2 on the straight line L3, the value (A min+5.0*Vave) can be −38.40, as an example. From the viewpoint of flight performance upon a shot with a fairway wood, the value (A min+5.0*Vave) can be not less than −38.98, for instance, not less than −38.85, such as not less than −38.40.

EXAMPLES

Hereinafter, advantageous effects of golf balls according to Examples will be described, but the scope of the present disclosure should not be construed in a limited manner based on the description of these Examples.

Example 1

A rubber composition was obtained by kneading 100 parts by mass of a polybutadiene (trade name “BR-730”, manufactured by JSR Corporation), 30 parts by mass of zinc acrylate, 6 parts by mass of zinc oxide, 10 parts by mass of barium sulfate, 0.5 parts by mass of diphenyl disulfide, and 0.5 parts by mass of dicumyl peroxide. This rubber composition was placed into a mold including upper and lower mold halves each having a hemispherical cavity, and heated at 170° C. for 18 minutes to obtain a core having a diameter of 39.7 mm. Meanwhile, a resin composition was obtained by kneading 50 parts by mass of an ionomer resin (trade name “Himilan 1605”, manufactured by DOW-MITSUI POLYCHEMICALS COMPANY, LTD.), 50 parts by mass of another ionomer resin (trade name “Himilan 1706”, manufactured by DOW-MITSUI POLYCHEMICALS COMPANY, LTD.), and 3 parts by mass of titanium dioxide. The above core was placed into a final mold having a large number of pimples on the inside face thereof, and the above resin composition was injected around the core by injection molding to form a cover having a thickness of 1.5 mm. A large number of dimples having a shape that is the inverted shape of the pimples were formed on the cover. A clear paint including a two-component curing type polyurethane as a base material was applied to this cover to obtain a golf ball of Example 1 having a diameter of about 42.7 mm and a mass of about 45.4 g. The golf ball has a PGA compression of about 85. The golf ball has the dimple pattern shown in FIGS. 2 and 3. The specifications of the dimples are shown in detail in Table 1 below.

Example 2 and Comparative Examples 1 and 2

Golf balls of Example 2 and Comparative Examples 1 and 2 were obtained in the same manner as Example 1, except that the final mold was changed. Each of these golf balls has the dimple pattern shown in FIGS. 2 and 3. The specifications of the dimples of these golf balls are shown in Tables 2 to 4 below.

Example 3

A golf ball of Example 3 was obtained in the same manner as Example 1, except that the final mold was changed. The dimple pattern of this golf ball is shown in FIGS. 6 and 7. The specifications of the dimples of this golf ball are shown in Table 5 below.

Comparative Examples 3 to 16

Commercially available golf balls were prepared as Comparative Examples 3 to 16.

Flight Test

A spoon (trade name “XXIO-12 W#3”, manufactured by Sumitomo Rubber Industries, Ltd., shaft hardness: S, loft angle:15°) was attached to a swing machine manufactured by Golf Laboratories, Inc. A golf ball was hit under a condition of a head speed of 43.0 m/sec, and the flight distance was measured. The flight distance is the distance from the hitting spot to the spot at which the golf ball stopped. The measurement was conducted 12 times, and the average value of the obtained data was calculated. The results are shown in Tables 6 to 9 below.

TABLE 1

Table 1 Specifications of Dimples Example 1

Dm
Dp2
Dp1
CR
V
Total

Number
(mm)
(mm)
(mm)
(mm)
(mm³)
(mm³)

A
76
4.40
0.1589
0.2726
15.31
2.075
157.7

B
158
4.30
0.1589
0.2674
14.62
1.945
307.2

C
76
4.15
0.1589
0.2600
13.63
1.761
133.8

D
16
3.75
0.1589
0.2414
11.14
1.335
21.4

E
8
3.00
0.1589
0.2117
7.16
0.750
6.0

334

626.1

TABLE 2

Table 2 Specifications of Dimples Example 2

Dm
Dp2
Dp1
CR
V
Total

Number
(mm)
(mm)
(mm)
(mm)
(mm³)
(mm³)

A
76
4.40
0.1526
0.2663
15.93
2.027
154.0

B
158
4.30
0.1526
0.2611
15.22
1.899
300.0

C
76
4.15
0.1526
0.2537
14.18
1.718
130.6

D
16
3.75
0.1526
0.2351
11.60
1.300
20.8

E
8
3.00
0.1526
0.2054
7.45
0.728
5.8

334

611.2

TABLE 3

Table 3 Specifications of Dimples Comparative Example 1

Dm
Dp2
Dp1
CR
V
Total

Number
(mm)
(mm)
(mm)
(mm)
(mm³)
(mm³)

A
76
4.40
0.1462
0.2599
16.63
1.978
150.3

B
158
4.30
0.1462
0.2547
15.88
1.852
292.6

C
76
4.15
0.1462
0.2473
14.80
1.675
127.3

D
16
3.75
0.1462
0.2287
12.10
1.265
20.2

E
8
3.00
0.1462
0.1990
7.77
0.705
5.6

334

596.1

TABLE 4

Table 4 Specifications of Dimples Comparative Example 2

Dm
Dp2
Dp1
CR
V
Total

Number
(mm)
(mm)
(mm)
(mm)
(mm³)
(mm³)

A
76
4.40
0.1399
0.2536
17.37
1.930
146.7

B
158
4.30
0.1399
0.2484
16.59
1.806
285.3

C
76
4.15
0.1399
0.2410
15.46
1.632
124.0

D
16
3.75
0.1399
0.2224
12.63
1.230
19.7

E
8
3.00
0.1399
0.1927
8.11
0.682
5.5

334

581.2

TABLE 5

Table 5 Specifications of Dimples Example 3

Dm
Dp2
Dp1
CR
V
Total

Number
(mm)
(mm)
(mm)
(mm)
(mm³)
(mm³)

A
108
4.40
0.1457
0.2594
16.68
1.974
213.2

B
48
4.30
0.1457
0.2542
15.94
1.848
88.7

C
152
4.15
0.1457
0.2468
14.85
1.671
254.0

D
30
3.65
0.1457
0.2238
11.50
1.173
35.2

E
12
2.85
0.1457
0.1933
7.04
0.618
7.4

350

598.5

TABLE 6

Evaluation Results

Com-
Com-

Ex-
Ex-
parative
parative
Ex-

ample
ample
Example
Example
ample

1
2
1
2
3

Front view
FIG. 2
FIG. 2
FIG. 2
FIG. 2
FIG. 6

Plan view
FIG. 3
FIG. 3
FIG. 3
FIG. 3
FIG. 7

N
334
334
334
334
350

TV (mm³)
626.1
611.2
596.1
581.2
598.5

Vave (mm³)
1.875
1.830
1.785
1.740
1.710

Amin (deg.)
−47.78
−48.13
−48.17
−48.54
−47.40

Amin + 5.0 * Vave
−38.40
−38.98
−39.24
−39.84
−38.85

Flight distance (m)
214.1
212.7
211.5
209.5
212.8

TABLE 7

Evaluation Results

Com-
Com-
Com-
Com-
Com-

parative
parative
parative
parative
parative

Ex-
Ex-
Ex-
Ex-
Ex-

ample
ample
ample
ample
ample

3
4
5
6
7

Front view
—
—
—
—
—

Plan view
—
—
—
—
—

N
348
352
328
352
346

TV (mm³)
570.1
591.7
583.2
567.2
564.4

Vave (mm³)
1.638
1.681
1.778
1.611
1.631

Amin (deg.)
−47.85
−48.28
−48.05
−47.36
−47.93

Amin + 5.0 *
−39.66
−39.87
−39.16
−39.31
−39.77

Vave

Flight
209.1
209.3
212.0
210.9
208.9

distance (m)

TABLE 8

Evaluation Results

Com-
Com-
Com-
Com-
Com-

parative
parative
parative
parative
parative

Ex-
Ex-
Ex-
Ex-
Ex-

ample
ample
ample
ample
ample

8
9
10
11
12

Front view
—
—
—
—
—

Plan view
—
—
—
—
—

N
330
330
338
338
338

TV (mm³)
586.5
572.4
567.2
574.6
593.6

Vave (mm³)
1.777
1.735
1.678
1.700
1.756

Amin (deg.)
−48.51
−48.14
−48.32
−48.06
−47.86

Amin + 5.0 *
−39.62
−39.47
−39.93
−39.56
−39.08

Vave

Flight
210.6
210.4
209.2
210.3
212.1

distance (m)

TABLE 9

Evaluation Results

Com-
Com-
Com-
Com-

parative
parative
parative
parative

Example
Example
Example
Example

13
14
15
16

Front view
—
—
—
—

Plan view
—
—
—
—

N
326
332
332
332

TV (mm³)
605.7
610.1
554.7
588.0

Vave (mm³)
1.858
1.838
1.671
1.771

Amin (deg.)
−48.71
−48.31
−47.46
−48.03

Amin + 5.0 * Vave
−39.42
−39.12
−39.10
−39.17

Flight distance (m)
210.7
212.2
211.9
211.8

As shown in Tables 6 to 9, the golf ball of each Example can have excellent flight performance upon a shot with a fairway wood. From the evaluation results, advantages of this golf ball are clear.

Disclosure Items

Each of the following items can be regarded as a preferred embodiment.

Item 1

A golf ball having a plurality of dimples on a surface thereof, wherein a trajectory calculated using a drag coefficient CD and a lift force coefficient CL obtained in an indoor test range which is a rule set by the United States Golf Association, on the basis of a model proposed by S. J. Quintavalla of the United States Golf Association and disclosed in “Science and Golf IV, Chapter 30, A Generally Applicable Model for the Aerodynamic Behavior of Golf Balls” published in 2002, by a program created in accordance with a manual provided by the United States Golf Association, under conditions of an initial speed of 260 ft/s, a launch angle of 15.0 degrees, and an initial backspin rate of 3000 rpm, satisfies the following mathematical formula,

Amin≥ 5.0*Vave−38.98,

wherein A min represents a minimum value (degree) of a vector angle A in the trajectory, and Vave represents an average volume (mm³) of the dimples, and

the vector angle A is calculated by the following mathematical formula,

A=ATAN(Vy/Vx),

wherein Vx represents a horizontal component of a speed of the golf ball, and Vy represents a vertical component of the speed of the golf ball.

Item 2

The golf ball according to Item 1, wherein a total number of the dimples is not less than 280 and not greater than 380.

Item 3

The golf ball according to Item 1 or 2, wherein the average volume Vave is not less than 1.40 mm³and not greater than 2.10 mm³.

Item 4

A golf ball having a plurality of dimples on a surface thereof, wherein a value (A min+5.0*Vave) in a trajectory calculated using a drag coefficient CD and a lift force coefficient CL obtained in an indoor test range which is a rule set by the United States Golf Association, on the basis of a model proposed by S. J. Quintavalla of the United States Golf Association and disclosed in “Science and Golf IV, Chapter 30, A Generally Applicable Model for the Aerodynamic Behavior of Golf Balls” published in 2002, by a program created in accordance with a manual provided by the United States Golf Association, under conditions of an initial speed of 260 ft/s, a launch angle of 15.0 degrees, and an initial backspin rate of 3000 rpm, is not less than −38.98,

Vave being an average volume (mm³) of the dimples, A min being a minimum value (degree) of a vector angle A calculated by the following mathematical formula, in the trajectory,

A=ATAN(Vy/Vx),

wherein Vx represents a horizontal component of a speed of the golf ball, and Vy represents a vertical component of the speed of the golf ball.

The above-described golf ball can be suitable for, for example, playing golf on golf courses and/or practicing at driving ranges.

Preferably, a total number of the dimples is not less than 280 and not greater than 380.

Preferably, the average volume Vave is not less than 1.40 mm³and not greater than 2.10 mm³.

This golf ball can have excellent flight performance upon a shot with a fairway wood.

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Priority Claims (1)