golf ball
The golf ball's dimple design, optimized for utility clubs, addresses the lack of performance in existing balls by enhancing flight characteristics through a calculated dimple volume and vector angle relationship, resulting in superior utility club shots.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SUMITOMO RUBBER INDUSTRIES LTD
- Filing Date
- 2022-01-31
- Publication Date
- 2026-05-15
AI Technical Summary
Existing golf balls do not prioritize superior flight performance when struck with utility clubs, which are commonly used for short and second shots on golf courses.
A golf ball design featuring multiple dimples optimized to achieve a specific relationship between the average dimple volume and maximum vector angle, calculated using drag and lift coefficients, to enhance flight performance with utility clubs.
The golf ball exhibits excellent flight performance when hit with utility clubs, achieving appropriate trajectories and distances.
Smart Images
Figure 0007859071000010 
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Figure 0007859071000012
Abstract
Description
[Technical Field]
[0001] This specification discloses a golf ball having a number of dimples on its surface. [Background technology]
[0002] Golf balls have numerous dimples on their surface. These dimples disrupt the airflow around the golf ball during flight, causing turbulent separation. This phenomenon is called "turbulence." Turbulence shifts the point at which air separates from the golf ball backward, reducing drag. Turbulence also exacerbates the misalignment between the upper and lower separation points of the golf ball caused by backspin, increasing the lift acting on the golf ball. This reduction in drag and increase in lift is called the "dimple effect." Superior dimples disrupt the airflow more effectively. Superior dimples result in greater flight distance.
[0003] Golfers' main concern with golf balls is their flight performance. They prefer golf balls that travel a long distance when struck with a driver (W#1). A golf ball capable of achieving long distances in driver shots is disclosed in Japanese Patent Publication No. 2014-140638. [Prior art documents] [Patent Documents]
[0004] [Patent Document 1] Japanese Patent Publication No. 2014-140638 [Overview of the project] [Problems that the invention aims to solve]
[0005] On short holes, golfers frequently use utility clubs for tee shots. They also frequently use utility clubs for second shots on longer holes. Golfers' interest is also focused on the distance the ball travels when hit with a utility club.
[0006] The applicant's intention is to provide a golf ball that exhibits superior flight performance when struck with a utility club. [Means for solving the problem]
[0007] The golf ball according to this embodiment has multiple dimples on its surface. Using the drag coefficient CD and lift coefficient CL obtained at an indoor test range according to the rules set by the United States Golf Association, and based on the model disclosed in "Science and Golf IV, Chapter 30, A Generally Applicable Model for the Aerodynamic Behavior of Golf Balls," published in 2002 and proposed by SJ Quintavalla of the United States Golf Association, the trajectory calculated under the conditions of an initial velocity of 260 ft / s, a launch angle of 15.0 degrees, and an initial backspin speed of 3000 rpm by a program created in accordance with the manual provided by the United States Golf Association, satisfies the following formula. Amax ≥ 4.0 * Vave + 13.10 In this formula, Amax represents the maximum value (degrees) of the vector angle A in the ballistic trajectory, and Vave represents the average volume (mm²) of the dimple. 3 This represents the vector angle A. This vector angle A is calculated by the following formula. A = ATAN(Vy / Vx) In this formula, Vx represents the horizontal component of the golf ball's velocity, and Vy represents the vertical component of the golf ball's velocity. [Effects of the Invention]
[0008] This golf ball has excellent flight performance in shots with utility clubs.
Brief Description of the Drawings
[0009] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a golf ball according to an embodiment. [Figure 2] FIG. 2 is an enlarged plan view showing the golf ball of FIG. 1. [Figure 3] FIG. 3 is a front view showing the golf ball of FIG. 2. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a part of the golf ball of FIG. 1. [Figure 5] FIG. 5 is a graph showing the relationship between the average volume of the dimples and the maximum vector angle of the golf ball of FIG. 1. [Figure 6] FIG. 6 is a plan view showing the golf ball of Example 3. [Figure 7] FIG. 7 is a front view showing the golf ball of FIG. 6.
Mode for Carrying Out the Invention
[0010] Hereinafter, preferred embodiments will be described in detail with reference to the drawings as appropriate.
[0011] The golf ball 2 shown in FIG. 1 includes a spherical core 4 and a cover 6 located outside the core 4. This golf ball 2 has a large number of dimples 8 on its surface. The portion of the surface of the golf ball 2 other than the dimples 8 is the land 10. This golf ball 2 has a paint layer and a mark layer outside the cover 6, but the illustration of these layers is omitted. The golf ball 2 may have one or more intermediate layers between the core 4 and the cover 6.
[0012] The diameter of this golf ball 2 is preferably between 40 mm and 45 mm. From the viewpoint of meeting the standards of the United States Golf Association (USGA), a diameter of 42.67 mm or more is particularly preferred. From the viewpoint of reducing air resistance, a diameter of 44 mm or less is more preferred, and 42.80 mm or less is particularly preferred.
[0013] The mass of this golf ball 2 is preferably between 40g and 50g. From the viewpoint of obtaining a large inertia, a mass of 44g or more is more preferable, and 45.00g or more is particularly preferable. From the viewpoint of satisfying USGA standards, a mass of 45.93g or less is particularly preferable.
[0014] Core 4 is formed by crosslinking a rubber composition. Examples of base rubbers for the rubber composition include polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-propylene-diene copolymer, and natural rubber. Two or more types of rubber may be used in combination. From the viewpoint of rebound performance, polybutadiene is preferred, and high-cis polybutadiene is particularly preferred.
[0015] The core 4 rubber composition contains a co-crosslinking agent. Preferred co-crosslinking agents from the viewpoint of rebound performance are zinc acrylate, magnesium acrylate, zinc methacrylate, and magnesium methacrylate. It is preferable that the rubber composition contains an organic peroxide together with the co-crosslinking agent. Preferred 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.
[0016] The core 4 rubber composition may contain additives such as fillers, sulfur, vulcanization accelerators, sulfur compounds, antioxidants, colorants, plasticizers, and dispersants. The rubber composition may contain carboxylic acids or carboxylates. The rubber composition may contain synthetic resin powder or crosslinked rubber powder.
[0017] The diameter of core 4 is preferably 30.0 mm or more, more preferably 37.0 mm or more, and particularly preferably 38.0 mm or more. The diameter of core 4 is preferably 42.0 mm or less, more preferably 41.5 mm or less, and particularly preferably 41.0 mm or less. Core 4 may have two or more layers. Core 4 may have ribs on its surface. Core 4 may be hollow.
[0018] Cover 6 is made of a resin composition. The preferred base polymer of this resin composition is an ionomer resin. A preferred ionomer resin is a binary copolymer of an α-olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms. Another preferred ionomer resin is a terpolymer of an α-olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester having 2 to 22 carbon atoms. In these binary and terpolymers, the preferred α-olefins are ethylene and propylene, and the preferred α,β-unsaturated carboxylic acids are acrylic acid and methacrylic acid. In these binary and terpolymers, 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.
[0019] The resin composition of cover 6 may contain other polymers in place of, or together with, the ionomer resin. Examples of other polymers include polyurethane, polystyrene, polyamide, polyester, and polyolefin. The resin composition may contain two or more polymers.
[0020] The resin composition of cover 6 may contain colorants such as titanium dioxide, fillers such as barium sulfate, dispersants, antioxidants, UV absorbers, light stabilizers, fluorescent agents, fluorescent whitening agents, etc. For the purpose of adjusting the specific gravity, this resin composition may also contain powders of high-density metals such as tungsten and molybdenum.
[0021] The thickness of cover 6 is preferably 0.3 mm or more, more preferably 1.0 mm or more, and particularly preferably 1.5 mm or more. The thickness of cover 6 is preferably 2.5 mm or less, more preferably 2.2 mm or less, and particularly preferably 2.0 mm or less. The specific gravity of cover 6 is preferably 0.90 or more and 1.10 or less. Cover 6 may have two or more layers.
[0022] As shown in Figures 2 and 3, the outline of each dimple 8 is circular. This golf ball 2 has dimple A with a diameter of 4.40 mm, dimple B with a diameter of 4.30 mm, dimple C with a diameter of 4.15 mm, dimple D with a diameter of 3.75 mm, and dimple E with a diameter of 3.00 mm. There are 5 types of dimples 8.
[0023] There are 76 dimples A, 158 dimples B, 76 dimples C, 16 dimples D, and 8 dimples E. The total number of dimples N is 334. These dimples 8 and lands 10 form a dimple pattern.
[0024] Figure 4 shows a cross-section of the golf ball 2 along a plane passing through the center of the dimple 8 and the center of the golf ball 2. The vertical direction in Figure 4 is the depth direction of the dimple 8. The dashed line 12 in Figure 4 represents a virtual sphere. The surface of the virtual sphere 12 is the surface of the golf ball 2 as it would be if the dimple 8 did not exist. The diameter of the virtual sphere 12 is the same as the diameter of the golf ball 2. The dimple 8 is recessed from the surface of the virtual sphere 12. The land 10 coincides with the surface of the virtual sphere 12. In this embodiment, the cross-sectional shape of the dimple 8 is substantially an arc. The radius of curvature of this arc is indicated by the symbol CR in Figure 4.
[0025] In Figure 4, the arrow Dm indicates the diameter of dimple 8. This diameter Dm is the distance between two tangent points Ed when a common tangent line Tg is drawn on both sides of dimple 8. The tangent points Ed are also the edges of dimple 8. The edges Ed define the contour of dimple 8.
[0026] The diameter Dm of each dimple 8 is preferably between 2.0 mm and 6.0 mm. Dimples 8 with a diameter Dm of 2.0 mm or more contribute to turbulence. From this viewpoint, a diameter Dm of 2.5 mm or more is more preferable, and 2.8 mm or more is particularly preferable. Dimples 8 with a diameter Dm of 6.0 mm or less do not impair the essential nature of the golf ball 2, which is substantially spherical. From this viewpoint, a diameter Dm of 5.5 mm or less is more preferable, and 5.0 mm or less is particularly preferable.
[0027] In Figure 4, the double-headed arrow Dp1 indicates the first depth of the dimple 8. This first depth Dp1 is the distance between the deepest part of the dimple 8 and the surface of the virtual sphere 12. In Figure 4, the double-headed arrow Dp2 indicates the second depth of the dimple 8. This second depth Dp2 is the distance between the deepest part of the dimple 8 and the tangent line Tg.
[0028] From the viewpoint of suppressing the hop of the golf ball 2, the first depth Dp1 of the dimple 8 is preferably 0.10 mm or more, more preferably 0.13 mm or more, and particularly preferably 0.15 mm or more. From the viewpoint of suppressing the drop of the golf ball 2, the first depth Dp1 is preferably 0.65 mm or less, more preferably 0.60 mm or less, and particularly preferably 0.55 mm or less.
[0029] The area S of dimple 8 is the area of the region enclosed by the outline of dimple 8 when the center of golf ball 2 is viewed from infinity. In the case of a circular dimple 8, the area S is calculated by the following formula. S = (Dm / 2) 2 * π
[0030] In the golf ball 2 shown in FIGS. 2 and 3, the area of dimple A is 15.21 mm 2 while the area of dimple B is 14.52 mm 2 while the area of dimple C is 13.53 mm 2 while the area of dimple D is 11.04 mm 2 while the area of dimple E is 7.07 mm 2 respectively.
[0031] In this specification, the ratio of the sum of the areas S of all the dimples 8 to the surface area of the virtual sphere 12 is referred to as the occupancy rate So. From the viewpoint of obtaining sufficient turbulence, the occupancy rate So is preferably 78% or more, more preferably 80% or more, and particularly preferably 82% or more. The occupancy rate So is preferably 95% or less. In the golf ball 2 shown in FIGS. 2 and 3, the total area of the dimples 8 is 4711.4 mm 2 while the surface area of the virtual sphere 12 of this golf ball 2 is 5728.0 mm 2 Therefore, the occupancy rate So is 82.3%.
[0032] From the viewpoint that an appropriate trajectory can be achieved in a shot with a utility club, the total number N of the dimples 8 is preferably 250 or more and 450 or less. The total number N is more preferably 270 or more, and particularly preferably 280 or more. The total number N is more preferably 410 or less, and particularly preferably 380 or less.
[0033] In this specification, the "volume V of the dimple" means the volume of the portion surrounded by the surface of the virtual sphere 12 and the surface of the dimple 8. The total volume TV of the dimples 8 is preferably 450 mm 3 or more and 750 mm 3 or less. In the golf ball 2 where the total volume TV is 450 mm 3 or more, the hop during flight is suppressed. From this viewpoint, the total volume TV is more preferably 480 mm 3 or more, and particularly preferably 500 mm 3 or more. In the golf ball 2 where the total volume TV is 750 mm 3 or less, the drop during flight is suppressed. From this viewpoint, the total volume TV is 700 mm3 The following is more preferable: 670mm 3 The following are particularly preferable.
[0034] In this specification, the average volume of dimple 8, Vave(mm²), is calculated using the following formula. 3 ) is calculated. Vave = TV / N From the perspective of achieving a proper trajectory in shots with utility clubs, the average volume Vave is 1.40 mm. 3 2.10mm 3 The following is preferable: Average volume Vave is 1.50 mm 3 The above is more preferable, 1.55 mm 3 The above is particularly preferable. The average volume Vave is 2.00 mm³. 3 The following is more preferable: 1.95 mm 3 The following are particularly preferable.
[0035] In the golf ball 2 shown in Figures 2 and 3, the volume of dimple A is 1.833 mm³. 3 Therefore, the volume of dimple B is 1.713 mm³. 3 The volume of dimple C is 1.545 mm³. 3 Therefore, the volume of dimple D is 1.159 mm³. 3 Therefore, the volume of dimple E is 0.637 mm³. 3 Therefore, the total volume TV of Dimple 8 is 551.1 mm². 3 Therefore, the total number of dimples N on this golf ball 2 is 334, and the average volume Vave is 1.650 mm³. 3 That is the case.
[0036] This specification describes how the drag coefficient CD and lift coefficient CL of golf ball 2 are measured under 15 conditions defined by the rules of the United States Golf Association (USGA) at an indoor test range (ITR). These drag coefficient CD and lift coefficient CL are used to calculate the trajectory of golf ball 2 using a program created in accordance with the USGA manual. The following conditions are also input into the program: Ball initial velocity: 260 ft / s (260 feet per second) Launch angle: 15.0 degrees Initial backspin speed: 3000 rpm This program calculates ball flight based on a model proposed by SJ 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.
[0037] This trajectory calculation allows us to determine the horizontal component Vx and the vertical component Vy of the golf ball 2's velocity every 0.1 seconds from the launch point to the landing point. From these horizontal component Vx and vertical component Vy, the vector angle A can be calculated using the following formula. A = ATAN(Vy / Vx) In other words, the vector angle A is calculated using the inverse tangent function of the ratio (Vy / Vx). This calculation yields the vector angle A (degrees) every 0.1 seconds from the launch point to the landing point. For example, for a trajectory with a flight time of 5.5 seconds, a vector angle A of 55 is obtained.
[0038] In this specification, the maximum value among multiple vector angles A from the launch point to the landing point is referred to as the maximum vector angle Amax (degree). According to the findings of the inventors, the maximum vector angle Amax affects the trajectory of a shot with a utility club. From the viewpoint of achieving a proper trajectory in a shot with a utility club, the maximum vector angle Amax is preferably between 18.50 degrees and 22.50 degrees. The maximum vector angle Amax is more preferably between 19.50 degrees and above, and particularly preferably between 20.00 degrees and above. The maximum vector angle Amax is more preferably between 21.50 degrees and below, and particularly preferably between 21.00 degrees and below.
[0039] Figure 5 is a graph showing the relationship between the average volume Vave of dimple 8 and the maximum vector angle Amax. In Figure 5, the points indicated by the symbol P1 are plots of golf ball 2 shown in Figure 1-4.
[0040] The straight line indicated by the sign L1 in Figure 5 is represented by the following formula. Amax = 4.0 * Vave + 13.10 As is clear from Figure 5, point P1 is located above the line L1. In other words, this golf ball 2 satisfies the following equation (1). Amax ≧4.0 * Vave + 13.10 (1) In this golf ball 2, the volume V of each dimple 8 is small, and the maximum vector angle Amax is large. According to the inventors' findings, the trajectory of a golf ball 2 that satisfies this equation (1) when struck with a utility club is appropriate. This golf ball 2 has excellent flight performance when shot with a utility club.
[0041] The straight line indicated by the sign L2 in Figure 5 can be expressed by the following formula. Amax = 4.0 * Vave + 13.24 As is clear from Figure 5, point P1 is located above the line L2. In other words, this golf ball 2 satisfies equation (2) below. Amax ≧4.0 * Vave + 13.24 (2) In this golf ball 2, the volume V of each dimple 8 is small, and the maximum vector angle Amax is large. According to the findings obtained by the inventors, the trajectory of a golf ball 2 that satisfies this equation (2) when struck with a utility club is appropriate. This golf ball 2 has excellent flight performance when shot with a utility club.
[0042] The straight line indicated by the symbol L3 in Figure 5 can be expressed by the following formula. Amax = 4.0 * Vave + 13.73 As is clear from Figure 5, point P1 is located above the line L3. In other words, this golf ball 2 satisfies equation (3) below. Amax ≧4.0 * Vave + 13.73 (3) In this golf ball 2, the volume V of each dimple 8 is small, and the maximum vector angle Amax is large. According to the inventors' findings, the trajectory of a golf ball 2 that satisfies this equation (3) when struck with a utility club is appropriate. This golf ball 2 has excellent flight performance when shot with a utility club.
[0043] For golf ball 2 on line L1, the value (Amax-4.0*Vave) is 13.10. For golf ball 2 on line L2, the value (Amax-4.0*Vave) is 13.24. For golf ball 2 on line L3, the value (Amax-4.0*Vave) is 13.73. From the viewpoint of flight performance in shots with a utility club, a value (Amax-4.0*Vave) of 13.10 or higher is preferable, 13.24 or higher is more preferable, and 13.73 or higher is particularly preferable. [Examples]
[0044] The effects of the golf balls described in the following examples will be clarified, but the scope disclosed herein should not be interpreted as limiting based on the description of these examples.
[0045] [Example 1] A rubber composition was obtained by kneading 100 parts by mass of polybutadiene (JSR's trade name "BR-730"), 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 in a mold consisting of an upper and lower mold, both equipped with hemispherical cavities, and heated at 170°C for 18 minutes to obtain a core with a diameter of 39.7 mm. Meanwhile, a resin composition was obtained by kneading 50 parts by mass of ionomer resin (Mitsui DuPont Polychemicals' trade name "Hymiran 1605"), 50 parts by mass of another ionomer resin (Mitsui DuPont Polychemicals' trade name "Hymiran 1706"), and 3 parts by mass of titanium dioxide. The above core was placed into a final mold equipped with numerous pimples on its inner surface, and the above resin composition was injected around the core by injection molding to form a cover with a thickness of 1.5 mm. Numerous dimples, which are inverted pimples, were formed on the cover. A clear coating based on two-component curing polyurethane was applied to this cover to obtain the golf ball of Example 1, which has a diameter of approximately 42.7 mm and a mass of approximately 45.4 g. The PGA compression of this golf ball is approximately 85. This golf ball has the dimple pattern shown in Figures 2 and 3. The detailed specifications of the dimples are shown in Table 1 below.
[0046] [Example 2 and Comparative Examples 1 and 2] Except for changing the final mold, golf balls for Example 2 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1. These golf balls have the dimple patterns shown in Figures 2 and 3, respectively. The specifications of the dimples on these golf balls are shown in Table 2-4 below.
[0047] [Example 3] Except for changing the final mold, the golf ball of Example 3 was obtained in the same manner as in Example 1. The dimple pattern of this golf ball is shown in Figures 6 and 7. The specifications of the dimples of this golf ball are shown in Table 5 below.
[0048] [Comparative Example 3-16] As comparative example 3-16, commercially available golf balls were prepared.
[0049] [Flight Test] A utility club (Sumitomo Rubber Industries' product name "XXIO-12 Hybrid H#3", shaft stiffness: S, loft angle: 18°) was mounted on Golf Laboratory's swing machine. A golf ball was struck under the condition of a head speed of 41.5 m / sec, and the distance was measured. The distance is the distance from the point of impact to the point where the golf ball came to rest. Twelve measurements were taken, and the average value of the obtained data was calculated. These results are shown in Table 6-9 below.
[0050] [Table 1]
[0051] [Table 2]
[0052] [Table 3]
[0053] [Table 4]
[0054] [Table 5]
[0055] [Table 6]
[0056] [Table 7]
[0057] [Table 8]
[0058] [Table 9]
[0059] As shown in Table 6-9, the golf balls of each embodiment exhibit superior flight performance in shots with utility clubs. This evaluation clearly demonstrates the superiority of these golf balls.
[0060] [Disclosure items] Each of the following items is a disclosure of a preferred embodiment.
[0061] [Item 1] A golf ball having multiple dimples on its surface, A golf ball whose trajectory, calculated using drag coefficients CD and lift coefficients CL obtained at an indoor test range according to the rules set by the United States Golf Association, and based on the model disclosed in "Science and Golf IV, Chapter 30, A Generally Applicable Model for the Aerodynamic Behavior of Golf Balls," published in 2002 and proposed by SJ Quintavalla of the United States Golf Association, satisfies the following formula, under the conditions of an initial velocity of 260 ft / s, a launch angle of 15.0 degrees, and an initial backspin speed of 3000 rpm. Amax ≥ 4.0 * Vave + 13.10 (In this formula, Amax represents the maximum value (degrees) of the vector angle A in the above trajectory, and Vave represents the average volume (mm²) of the dimples.) 3 This represents the above vector angle A. The above vector angle A is calculated by the following formula. A = ATAN(Vy / Vx) In this formula, Vx represents the horizontal component of the golf ball's velocity, and Vy represents the vertical component of the golf ball's velocity.
[0062] [Item 2] A golf ball as described in item 1, wherein the total number of dimples is between 280 and 380.
[0063] [Item 3] The above average volume Vave is 1.40 mm 3 2.10mm 3 The golf balls listed in item 1 or 2 below.
[0064] [Item 4] A golf ball having multiple dimples on its surface, A golf ball in which the drag coefficient CD and lift coefficient CL obtained at an indoor test range according to the rules set by the United States Golf Association (USA), and whose trajectory value (Amax-4.0*Vave) calculated under the conditions of an initial velocity of 260 ft / s, a launch angle of 15.0 degrees, and an initial backspin speed of 3000 rpm is 13.10 or higher, is calculated using a program created in accordance with the manual provided by the USA, based on the model disclosed in "Science and Golf IV, Chapter 30, A Generally Applicable Model for the Aerodynamic Behavior of Golf Balls," published in 2002 and proposed by SJ Quintavalla of the USA, and using drag coefficient CD and lift coefficient CL obtained at an indoor test range according to the rules set by the USA, and based on the model, the launch angle of 15.0 degrees, and an initial backspin speed of 3000 rpm. Vave: Average volume of the above dimple (mm²) 3 ) Amax: The maximum value (in degrees) of the vector angle A calculated by the following formula in the above trajectory. A = ATAN(Vy / Vx) (In this formula, Vx represents the horizontal component of the golf ball's velocity, and Vy represents the vertical component of the golf ball's velocity.) [Industrial applicability]
[0065] The aforementioned golf balls are suitable for playing on a golf course, practicing at a driving range, etc. [Explanation of Symbols]
[0066] 2. Golf balls 4 cores 6. Cover 8... Dimples 10...land 12.. Virtual sphere
Claims
1. A golf ball having multiple dimples on its surface, The drag coefficient CD and lift coefficient CL obtained at an indoor test range, as per the rules set by the United States Golf Association, are used. Based on the model disclosed in "Science and Golf IV, Chapter 30, A Generally Applicable Model for the Aerodynamic Behavior of Golf Balls," published in 2002 and proposed by SJ Quintavalla of the United States Golf Association, a program created in accordance with the manual provided by the United States Golf Association, calculated under the conditions of an initial velocity of 260 ft / s, a launch angle of 15.0 degrees, and an initial backspin velocity of 3000 rpm, the value (Amax - 4.0 * Vave) for the trajectory is 13.24 or higher. Here, Amax represents the maximum value (degree) of the vector angle A in the above trajectory, and Vave represents the average volume (mm²) of the dimple. ３ ) represents the above vector angle A, and is calculated by the following formula: A = ATAN(Vy / Vx) In this formula, Vx represents the horizontal component of the golf ball's velocity, and Vy represents the vertical component of the golf ball's velocity.
2. The golf ball according to claim 1, wherein the total number of dimples is 280 or more and 380 or less.
3. The above average volume Vave is 1.40 mm ３ The above is 2.10 mm. ３ The golf ball according to claim 1 or 2, wherein the golf ball is as follows: