JP2003290391A - Golf ball - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf ball 1 superior in both a ball hitting feeling and a carry. <P>SOLUTION: Mass of the golf ball 1 is ≥41.0 g and ≤44.5 g. The golf ball 1 is provided with a multiplicity of dimples on its surface. A surface area occupation ratio Y of the dimples is ≥0.80 and ≤0.90. An average occupation ratio (y) that is a value of dividing the surface area occupation ratio Y by a total number of the dimples is ≥0.00220. A sum total X of outline lengths (x) of the dimples and the surface area occupation ratio Y satisfy a relationship of a mathematical expression I of X≤3882×Y+1495. A proportion R of dimples with the outline length x of ≥10.5 mm in the total number of dimples is ≥91%. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball, and more particularly to improvement of a golf ball dimple.

[0002]

2. Description of the Related Art A golf ball hit by a golf club flies in the air and eventually falls. During flight, the golf ball gradually slows down. A major concern for golfers is flight distance. Golfers want a golf ball with excellent flight performance. The higher the velocity (initial velocity) of the golf ball immediately after hitting, the longer the flight distance tends to be. Golf ball manufacturers have been making efforts to develop golf balls with high initial velocity for many years, but the initial velocity cannot exceed the current level. This is because the upper limit of the initial velocity is defined in the rules of the American Golf Association (USGA), and the initial velocity of a golf ball of a leading manufacturer almost reaches this upper limit.

The USGA also sets in its rules an upper mass limit for golf balls of 45.92 g.
This rule only sets the upper limit of mass, not the lower limit. In other words, the golf ball cannot be judged to be non-compliant with the rule because of its light mass. However, the mass of commercially available golf balls is set to a large value within the range of not exceeding 45.92 g. This is because the larger the mass, the greater the inertia of the golf ball, and therefore the less deceleration during flight. With the exception of floating balls used in water practice ranges, the mass of most commercially available golf balls is controlled within the range of 45.0 g to 45.92 g.

A golf ball has about 200 to 550 dimples on its surface. The role of dimples is to promote the turbulent transition of the boundary layer by disturbing the air flow around the golf ball during flight.
This is to cause turbulent flow separation (hereinafter referred to as "dimple effect"). By promoting the turbulent transition, the separation point of air from the golf ball is lowered backward, and the drag coefficient (C
d) becomes smaller and the flight distance of the golf ball increases.
In addition, the promotion of the turbulent flow transition promotes the difference in the separation points between the upper side and the lower side of the golf ball due to backspin, and the lift force acting on the golf ball is increased. Various proposals have been made to improve dimple patterns intended to improve flight performance.

The shot feeling of a golf ball is an important required characteristic as well as the flight performance. Golfers prefer golf balls that have a light feel at impact. This is because a golf ball with a heavy feel at impact gives a golfer pain. A golfer's swing form may be disturbed by repeated pain. The shot feeling correlates with the impact force when the golf ball and the golf club collide. The smaller the impact force, the lighter the shot feeling.

Japanese Patent Laid-Open No. 4-314462 (Patent No. 3)
No. 005066) discloses a golf ball which has an improved shot feeling due to its reduced weight. The lighter the golf ball, the greater the degree of deceleration during flight. However, in the golf ball disclosed in the above publication, the reduction in flight distance is suppressed by the improvement of the dimples.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to further improve the flight performance of a lightweight golf ball. In other words, the object of the present invention is to provide a golf ball excellent in both shot feeling and flight distance.

[0008]

A golf ball according to the present invention has a large number of dimples on its surface. The surface area occupation ratio Y of the dimples in this golf ball is 0.8.
The average occupancy y, which is a value obtained by dividing the surface area occupation ratio Y by the total number of dimples, is 0 to 0.90 and is 0.00
220 or more. The golf ball has a mass of 41.
It is 0 g or more and 44.5 g or less.

According to the knowledge obtained by the present inventor, a golf ball having a larger average occupancy y tends to have superior flight performance. The golf ball according to the present invention has an average occupation ratio y of 0.
Since it is 00220 or more, it is excellent in flight performance despite being lightweight. Since this golf ball is lightweight, it has a small impact force when hit. This golf ball is excellent in both shot feeling and flight distance.

Preferably, the total (total contour length) X of the contour lengths x of the dimples and the surface area occupation ratio Y satisfy the relationship represented by the following mathematical expression (I). X ≦ 3882 × Y + 1495 --- (I) This golf ball is provided with a dimple pattern having a small total contour length X instead of the surface area occupation ratio Y. This golf ball exhibits more excellent flight performance.

Preferably, the ratio R of the number of dimples having the contour length x of 10.5 mm or more to the total number of dimples is 91% or more. This golf ball exhibits particularly excellent flight performance.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, with reference to the drawings,
The present invention will be explained in detail based on the preferred embodiments.

FIG. 1 is a partially cutaway sectional view showing a golf ball 1 according to an embodiment of the present invention. The golf ball 1 includes a spherical core 2 and a cover 3. The core 2 is formed by crosslinking a rubber composition. The cover 3 is made of a resin composition containing a synthetic resin (typically, an ionomer resin) as a main component.
A large number of dimples 4 are formed on the surface of the cover 3. The golf ball 1 includes a paint layer and a mark layer on the outer side of the cover 3, but these are not shown. The diameter of this golf ball 1 is usually 40
mm to 45 mm, in particular 42 mm to 44 mm. The diameter is 4 from the viewpoint of reducing the air resistance within the range where the standards of the US Golf Association (USGA) are satisfied.
It is preferably 2.67 mm or more and 42.80 mm or less.

This golf ball 1 is lighter than a normal golf ball 1 and has a mass of 41.0 g or more and 44.5 g or less. The impact force when the lightweight golf ball 1 is hit by a golf club is small. A golfer who hits the golf ball 1 feels that the shot feeling is light. From the viewpoint of feel at impact, the mass is more preferably 44.2 g or less, and 4
It is particularly preferably 4.0 g or less. If the mass is too small, inertia is insufficient and the golf ball 1 decelerates greatly during flight,
Therefore, flight performance may be insufficient. From this viewpoint, the mass is more preferably 41.5 g or more and 42.0 g.
The above is particularly preferable.

The base rubber of the core 2 is polybutadiene,
Polyisoprene, styrene-butadiene copolymer, ethylene-propylene-diene copolymer, natural rubber and the like are preferable. Two or more of these rubbers may be used in combination.
From the viewpoint of resilience performance, it is preferable that polybutadiene is the main component. Among polybutadiene, cis-1,
High-cis polybutadiene having a ratio of four bonds of 40% or more, particularly 80% or more is preferable.

The core 2 is generally mixed with a filler such as zinc oxide or barium sulfate. By reducing the amount of the filler, the core 2 has a low specific gravity, and the lightweight golf ball 1 is obtained. The low specific gravity of the core 2 can also be achieved by blending a filler having a small specific gravity such as zinc stearate in place of the filler or together with the filler. By using a porous material for the core 2,
The core 2 may have a low specific gravity. The lightweight structure of the golf ball 1 may be achieved by having a hollow structure.

FIG. 2 is an enlarged plan view showing the golf ball 1 of FIG. 1, and FIG. 3 is a front view thereof. This golf ball 1 has an A dimple having a circular plan shape and a diameter of 4.5 mm and a circular dimple having a plan shape of 4.
It has a B dimple having a diameter of 1 mm, a C dimple having a circular plane shape and a diameter of 3.6 mm, and a D dimple having a circular plane shape and a diameter of 2.8 mm. The number of A dimples is 130, the number of B dimples is 150, and the number of C dimples is 6.
The number is 0 and the number of D dimples is 32. The total number of dimples in this golf ball 1 is 372.

FIG. 4 is a schematic enlarged sectional view showing a part of the golf ball 1 of FIG. In this figure, a cross section passing through the deepest part of the dimple 4 is shown. In this figure, what is indicated by a double-headed arrow d is the diameter of the dimple 4. This diameter d is the distance between both contact points when a common tangent line is drawn on both ends of the dimple 4. Further, the volume of the portion surrounded by the phantom sphere of the golf ball 1 (a sphere when it is assumed that the dimples 4 do not exist, which is indicated by the chain double-dashed line in FIG. 4) and the surface of the dimples 4 , The dimple volume.

The area of the dimple 4 is the area of the region surrounded by the contour of the dimple 4 (that is, the area of the plane shape) when the center of the golf ball 1 is viewed from infinity.
In the case of the dimple 4 having a circular shape, the area s is calculated by the following mathematical formula. s = (d / 2) ² × π FIGS. 2 and 3
The golf ball 1 shown in FIG.
Is 15.9 mm ² , and the area s of the B dimple is 1
It is 3.2 mm ² , and the area s of the C dimple is 10.2.
mm ² and the area s of the D dimple is 6.2 mm ² . Therefore, the sum (total area) S of the dimple areas is
It is 4855.7 mm ² . The surface area occupation ratio Y is calculated by dividing the total area S by the surface area of the phantom sphere. In this golf ball 1, the surface area occupation ratio Y is 0.8.
48. The surface area occupation ratio Y means the area ratio of all the dimples 4 to the spherical surface of the virtual sphere. The average occupancy y is calculated by dividing the surface area occupancy Y by the total number of dimples. In this golf ball 1, the average occupation ratio y is 0.00228. The average occupation rate y means the area ratio of the dimples 4 having the average area to the spherical surface of the phantom sphere.

When the designer intends to design a dimple pattern having a large surface area occupation ratio Y, there is a means for increasing the number of dimples to achieve the surface area occupation ratio Y. Further, by increasing each individual dimple 4, There are also means for achieving the surface area occupation ratio Y. The designer mainly adopts the means for increasing the dimple 4 to achieve the surface area occupation ratio Y, whereby the golf ball 1 having the average occupation ratio y of 0.00220 or more can be obtained.

In the golf ball 1 having an average occupancy y of 0.00220 or more, the drag coefficient (Cd) is small in a region where the flight speed in the trajectory is large. Since this golf ball 1 is lightweight, it has a small inertia, but its flight force is supplemented by its small drag force. Although this golf ball 1 is lightweight, it has an excellent flight distance. From this viewpoint, the average occupation ratio y is more preferably 0.00225 or more, further preferably 0.00230 or more, and 0.002 or more.
50 or more is particularly preferable. In the golf ball 1 having an extremely large average occupancy y, the original characteristic that the golf ball is substantially spherical cannot be maintained.
It is preferably 00300 or less.

The surface area occupation ratio Y is 0.80 or more and 0.90.
The following are preferred. If the surface area occupation ratio Y is less than the above range, the lift of the golf ball 1 during flight may be insufficient. From this viewpoint, the surface area occupation ratio Y is more preferably 0.81 or more, and particularly preferably 0.83 or more. Further, if the surface area occupation ratio Y exceeds the above range, there is a possibility that the trajectory will rise. From this viewpoint, the surface area occupation ratio Y is particularly preferably 0.87 or less.

In the golf ball 1 shown in FIGS. 2 and 3, the contour length x of the A dimple is 14.1 mm,
The contour length x of the B dimple is 12.9 mm, the contour length x of the C dimple is 11.3 mm, and the contour length x of the D dimple is 8.8 mm. In this golf ball 1, the total contour length X, which is the sum of the contour lengths x, is 47
It is 30.0 mm.

The contour length x of the dimple 4 is a length measured along the contour of the dimple 4. For example, in the case of a dimple having a triangular planar shape, the total length of the three sides is the contour length x. Since this side exists on the spherical surface, it is not a straight line but a circular arc in a strict sense.
The length of this arc is the length of the side. In the case of the circular dimple 4, the contour length x is calculated by the following mathematical formula. x = d × π

It is preferable that the surface area occupation ratio Y and the total contour length X satisfy the relationship represented by the following formula (I). X ≦ 3882 × Y + 1495-(I) In this golf ball 1, the total contour length X is small in place of the surface area occupation ratio Y. This golf ball 1 is a golf ball 1 having a small drag coefficient (Cd) during flight, and has excellent flight performance. To the inventor's knowledge, no golf ball 1 satisfying the above formula (I) has ever existed.

From the viewpoint of reducing the drag coefficient (Cd), it is more preferable that the total contour length X and the surface area occupation ratio Y satisfy the following formula (II), further preferably the following formula (III), and It is particularly preferable to satisfy the formula (IV). X ≦ 3882 × Y + 1445 −− (II) X ≦ 3882 × Y + 1335 −− (III) X ≦ 3882 × Y + 1085 −− (IV) In order to maintain the original characteristic of the golf ball, , The total contour length X and the surface area occupation ratio Y need to satisfy the relationship of the following mathematical expression (V). X ≧ 3882 × Y + 95 --- (V)

The total contour length X is appropriately determined from the relationship with the surface area occupation ratio Y within a range satisfying the above mathematical expression (I).
Usually 2800 mm or more and 5000 mm or less, especially 31
It is set to 00 mm or more and 4700 mm or less.

From the viewpoint of reducing the drag coefficient (Cd), the ratio R of the number of dimples 4 having the contour length x of 10.5 mm or more to the total number of dimples is preferably 91% or more, and 95% or more. Is particularly preferred. This ratio R is ideally 100%. In the golf ball 1 shown in FIGS. 2 and 3, the ratio R is 91.4%.

The size of each dimple 4 is not particularly limited, but the diameter d of the circular dimple 4 is usually 2.0 mm or more and 8.0 mm or less, and particularly 3.0 mm or more and 7.0 mm or less. . The dimples 4 formed may be of a single type or a plurality of types. Further, instead of the circular dimples or together with the circular dimples, a non-circular dimple (a dimple whose planar shape is not circular) may be formed.

The total dimple volume (total volume) is 30.
It is preferably 0 mm ³ or more and 700 mm ³ or less. If the total volume is less than the above range, the trajectory may blow up. From this viewpoint, the total volume is particularly preferably 350 mm ³ or more. When the total dimple volume exceeds the above range,
There is a risk that the trajectory will drop. From this perspective,
It is particularly preferable that the total volume is 600 mm ³ or less.

The total number of dimples 4 is 200 or more and 50 or more.
0 or less is preferable. If the total number is less than the above range, it is difficult to maintain the desired surface area occupation ratio Y. From this perspective,
It is particularly preferable that the total number is 250 or more. If the total number exceeds the above range, the average occupation ratio y may be small. From this viewpoint, the total number is preferably 400 or less.

The structure of the golf ball is not particularly limited and may be a so-called wound golf ball or a solid golf ball (one-piece golf ball, two-piece golf ball, three-piece golf ball, etc.). The material is not particularly limited, and known materials can be used.

[0033]

EXAMPLES The effects of the present invention will be clarified below based on Examples, but the present invention should not be construed in a limited way based on the description of the Examples.

[Example 1] A core made of solid rubber and having a diameter of 38.4 mm was placed in a mold, and the ionomer resin composition was injected around the core to form a cover layer. The surface of this cover layer is painted and the plan view is shown in FIG.
A golf ball of Example 1 having a dimple pattern whose front view is FIG. 3 was obtained. The golf ball has an outer diameter of about 42.70 mm, a mass of 44.5 g, a compression (by ATTI compression tester of Atti Engineering Co., Ltd.) of about 93, and a total dimple volume of about 500 mm ³ .

[Examples 2 to 8 and Comparative Examples 1 to 7] The molds were changed so that the dimple specifications were as shown in Tables 1 and 2 below, and the type and blending amount of the filler in the core were changed. Golf balls of Examples 2 to 8 and Comparative Examples 1 to 7 were obtained in the same manner as in Example 1 except that the weights were adjusted as shown in Tables 3 and 4 below. A plan view of golf balls according to Examples 2 to 4 and Comparative Examples 1 and 2 is shown in FIG. 2, and a front view thereof is shown in FIG. A plan view of the golf balls according to Examples 5 and 6 is shown in FIG. 5, and a front view thereof is shown in FIG. A plan view of golf balls according to Examples 7 and 8 is shown in FIG.
The front view is shown in FIG. A plan view of golf balls according to Comparative Examples 3 to 6 is shown in FIG. 9, and a front view thereof is shown in FIG. A plan view of the golf ball according to Comparative Example 7 is shown in FIG. 11, and a front view thereof is shown in FIG.

[0036]

[Table 1]

[0037]

[Table 2]

[Flying Distance Test] A swing machine (manufactured by Golf Lab) was equipped with a driver (“XXIO W # 1” manufactured by Sumitomo Rubber Industries, loft: 8 °, shaft hardness: X) equipped with a metal head. . And the head speed is 5
The machine conditions were set so as to be 0 m / sec. A golf ball kept at 23 ° C. was hit with this swing machine and the flight distance (distance from the launch point to the rest point) was measured. Average values of 20 measurement results are shown in Tables 3 and 4 below.

[Evaluation of shot feeling] Ten advanced golfers were made to hit a golf ball with a driver equipped with a metal head, and the shot feeling was evaluated. The results are shown in Tables 3 and 4 below.

[0040]

[Table 3]

[0041]

[Table 4]

In Tables 3 and 4, the golf balls of Comparative Examples 1 and 3 are inferior in shot feeling. Comparative Examples 2, 4, 5, 6
The golf balls of 7 and 7 are inferior in flight distance. In contrast,
The golf balls of each example are excellent in both flight distance and shot feeling. From this evaluation result, the superiority of the present invention is clear.

[0043]

As described above, the golf ball of the present invention is excellent in both shot feeling and flight distance. This golf ball gives the golfer hitting it a refreshing feeling,
And contribute to the improvement of the score.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view showing a golf ball according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing the golf ball of FIG.

FIG. 3 is an enlarged front view showing the golf ball of FIG.

FIG. 4 is a schematic enlarged cross-sectional view showing a part of the golf ball of FIG.

FIG. 5 is a plan view showing golf balls according to Examples 5 and 6 of the present invention.

FIG. 6 is a front view showing the golf ball of FIG.

FIG. 7 is a plan view showing golf balls according to Examples 7 and 8 of the present invention.

FIG. 8 is a front view showing the golf ball of FIG. 7.

FIG. 9 is a plan view showing golf balls according to Comparative Examples 3 to 6.

FIG. 10 is a front view showing the golf ball of FIG. 9.

FIG. 11 is a plan view showing a golf ball according to comparative example 7.

FIG. 12 is a front view showing the golf ball of FIG. 11.

[Explanation of symbols]

1 ... golf ball 2 ... core 3 ... Cover 4 ... Dimples A ... A dimple B ... B dimple C ... C dimple D ... D dimple E ... E dimple

Claims (3)

[Claims] 1. A surface is provided with a large number of dimples,
The surface area occupation ratio Y of these dimples is 0.80 or more and 0.90 or less, and the average surface occupation ratio y which is a value obtained by dividing the surface area occupation ratio Y by the total number of dimples is 0.00220.
The above is the golf ball having a mass of 41.0 g or more and 44.5 g or less. 2. The golf ball according to claim 1, wherein the total X of the contour lengths x of the dimples and the surface area occupation ratio Y satisfy the relationship represented by the following formula (I). X ≦ 3882 × Y + 1495 −−− (I) 3. The golf ball according to claim 1, wherein a ratio R of the number of dimples having the contour length x of 10.5 mm or more to the total number of dimples is 91% or more.