JPH1043343A - Practice golf balls - Google Patents

Abstract

(57) Abstract: A golf ball having a large number of dimples formed on its surface has a weight of 46.5 to 49.0 g and a deformation amount of the ball at a constant load of 100 kg of 2.5 to 45.0 g. The ratio of the sum of all the dimples of the dimple space volume under the plane surrounded by the edge of each dimple to 4.0 mm and the total volume of the virtual sphere assuming that there is no dimple on the golf ball surface is 0.7 to 0.7%. A practice golf ball characterized by being 1.1%. The golf ball of the present invention has a good feeling at impact, has a sufficiently low trajectory at the time of flight, and suppresses a decrease in the flight distance. Therefore, the golf ball is particularly constructed in a limited space. It can be suitably used in urban driving ranges.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a practice golf ball which can achieve a low trajectory without deteriorating the flight distance performance, has a good feeling, and can be suitably used particularly in a narrow golf practice range. .

[0002]

2. Description of the Related Art
In cities, etc., so-called urban golf practice ranges, in which the site is limited by ball-proof nets due to location requirements, are often used, but practice golf balls used in such practice ranges have high trajectories. If the ball is easily formed, the ball may jump out beyond the ball-proof net and give danger to the surroundings.

[0003] Therefore, there is a need for a practice golf ball that provides a low trajectory with a low risk of jumping over a ball-proof net.

[0004] From such a point, Japanese Patent Laid-Open No. 4-11796
No. 9 discloses a weight of 43 to 48 g and a diameter of 1.65 to 1.65 g.
A practice golf ball having a size of 71 inches, 300 to 550 dimples, and a total dimple volume of 400 to 600 mm ³ has been proposed, but there is still room for improvement in trajectory height.

[0005] The practice golf ball not only has a low trajectory but also has a sufficient flight distance, has a good feeling, and gives a good feeling when shot. Although it is necessary to do so, conventional practice golf balls have not been sufficiently considered in this respect.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a practice golf ball that provides sufficient low trajectory while maintaining the flight distance performance and has a good hit feeling.

[0007]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above-mentioned object, and as a result, a normal golf ball for competition must satisfy the standards set forth in the Rules of Golf. It is specified that the weight should be 45.92 g or less. However, when obtaining a practice golf ball, it is not always necessary to satisfy this standard. The trajectory of golf balls has been reduced.

That is, 46.5 which is heavier than the upper limit of the golf rules.
By obtaining a golf ball weighing ４９49.0 g, the effect of gravity acting on the ball during flight was enhanced, the excessive climb of the ball was suppressed, and the trajectory was reduced. However, the gravitational effect alone does not achieve sufficient trajectory reduction, and there is a possibility that the flight distance may be reduced. Therefore, as a result of further study, the ratio of the sum total of all dimples of the dimple space volume under the plane surrounded by the edge of each dimple to the total volume of the virtual sphere assuming that there is no dimple on the golf ball surface (dimple total The volume ratio V _r ) is set in the range of 0.7 to 1.1%. In this case, more effectively, the dimple space volume below the plane surrounded by the edges of the individual dimples is defined as the above-mentioned plane as a bottom surface. maximum by a value V ₀ obtained by dividing the 0.40 to 0.65 in cylinder volume and depth height, finding that sufficient low trajectory of while suppressing a decrease in distance is achieved dimples did.

Further, when the ball weight is simply increased as described above, the impact force received by the hitter at the time of impact becomes larger than that of a ball having a normal weight, so that the hit feeling at the time of play is not reproduced, and the sense of practice is not obtained. Is not utilized in actual play, but when the amount of deformation when a 100 kg load is applied to the ball is formed to be 2.5 to 4.0 mm, the ball has an excellent hit feeling similar to that of a normal competition ball. This has led to the achievement of the present invention.

Therefore, the present invention provides a golf ball having a large number of dimples formed on its surface, and having a weight of 46.5.
４９49.0 g, the amount of deformation of the ball under a constant load of 100 kg is 2.5-4.0 mm, and the sum of all dimples in the dimple space volume below the plane surrounded by the edge of each dimple and golf A practice golf ball characterized by having a ratio of 0.7 to 1.1% with respect to the total volume of the virtual sphere assuming that there is no dimple on the ball surface, and as a preferred embodiment thereof, The value V _{0 obtained} by dividing the volume of the dimple space under the plane surrounded by the edge by the volume of a cylinder having the above-mentioned plane as the bottom surface and the maximum depth of the dimple from this bottom surface as the height is 0.40.
A training golf ball is provided.

Hereinafter, the present invention will be described in more detail. The practice golf ball of the present invention can be formed as a one-piece solid golf ball, a two-piece golf ball having a solid core covered with a cover, and the like, and its weight is 46.5. -49.0 g, especially 46.5-48.0 g. If the weight is more than 49.0 g, the gravity applied to the ball is too large to greatly reduce the flight distance, and the impact force at the time of impact is large, so that the hit feeling becomes very poor,
If the weight is less than 46.5 g, it is not possible to sufficiently reduce the trajectory due to the gravitational effect, and the trajectory tends to be high, so that the object of the present invention cannot be achieved.

In this case, the ball diameter is appropriately selected and is not particularly limited, but may be the same as a normal practice golf ball, and is 42.3 to 43.0 mm, more preferably 42.3 mm.
It can be 5 to 42.8 mm.

Further, the golf ball of the present invention has a
g The amount of deformation of the ball under a constant load is 2.5 mm or more,
Preferably 2.7 mm or more, more preferably 2.8 mm
The above is formed. If the deformation amount is less than 2.5 mm, the impact force at the time of impact becomes large, and the hit feeling becomes poor, so that the object of the present invention cannot be achieved. The upper limit of the deformation is 4.0 mm or less, particularly 3.8 mm or less. If the upper limit is greater than 4.0 mm, the ball is poorly separated at impact and impairs the feel at impact.

Further, in the golf ball of the present invention, a large number of dimples are formed on the surface of the golf ball. In this case, the sum of all the dimples in the dimple space volume below the plane surrounded by the edge of each dimple is the sum of the dimples on the surface of the golf ball. in 0.7 to 1.1% the percentage (total dimple volume ratio V _r) to the total volume of a phantom sphere assuming the dimple is not, preferably 0.8 to 1.05%, more preferably 0.9 ~ 1.0
%. More preferably, the value V ₀ obtained by dividing the dimple space volume below the plane surrounded by the edge of each dimple by the volume of a cylinder having the above-mentioned plane as the bottom surface and the maximum depth of the dimple from this bottom surface as the height is 0. .
40 to 0.65, especially 0.43 to 0.60. By thus performing the dimple design that satisfies V _r values and V ₀ values, respectively, reduce the drag coefficient of the ball, and is capable to measure the increase in distance increases the lift coefficient . In this case, if V ₀ exceeds 0.65, the ball may blow up and stall, and a sufficient flight distance may not be obtained. If V ₀ is less than 0.40, the trajectory may drop. Could be. on the other hand,
If the _Vr value is less than 0.7%, the spin is applied too much,
On the other hand, if it exceeds 1.1%, it is not possible to sufficiently reduce the drag coefficient.

Here, the dimple shape will be described in more detail. When the dimple planar shape is circular, FIG.
As shown in FIG. 5, a virtual sphere 2 having a ball diameter is set on the dimple 1 and a sphere 3 having a diameter smaller than the ball diameter by 0.16 mm is set. An intersection 4 between the circumference of the sphere 3 and the dimple 1 is obtained. A series of intersections 6 between the tangent line 5 at the intersection 4 and the virtual spherical surface 2 is referred to as a dimple edge 7. In this case, the setting of the dimple edge 7 described above is because the edge of the dimple 1 is usually rounded, and without such setting, the exact position of the dimple edge cannot be determined. Then, as shown in FIGS. 2 and 3, the volume V _p of the dimple space 9 below the plane (circle: diameter D _m ) 8 surrounded by the edge 7 is obtained. On the other hand, the plane 8
, And the maximum dimple depth D _p from this plane 8
Is calculated, the ratio V ₀ of the dimple space volume V _p to the volume V _Q of the cylinder 10 having the height as V is calculated.

[0016]

(Equation 1)

If the plane shape of the dimple is not circular, the maximum diameter (or maximum plane length) of this dimple is determined, and it is assumed that the dimple plane is circular having this maximum diameter (maximum length). Then, V ₀ is calculated in the same manner as above.

Further, the total dimple volume ratio V _r is a value which can be a sum of the dimple spatial volume V _p which is formed on the surface of the golf ball is calculated by the following equation.

[0019]

(Equation 2) (However, V _s is the sum of the dimple spatial volume V _p under the plane surrounded by the edge of each dimple, R is the radius of the ball.)

[0020] The above formula V _s can be represented by the following formula, the resulting V _s by substituting the equation for the V _r, can be calculated V _r.

[0021]

(Equation 3)(However, V _p1, V _p2... V _pnAre of different sizes.
Represents the volume of the sample, N₁, N_Two... N_nIs V _p1,
V _p2... V _pnRepresents the number of dimples having a volume of )

The total number, shape, size, type, etc. of the dimples formed on the golf ball of the present invention are not limited, but the total number is 350 to 450, especially 340 to 4
Preferably, the number is 40. Further, the arrangement of the dimples may be the same as that of a normal golf ball, and the number of dimples may be two or more, particularly two to four, having different diameters and depths. It is preferably in the range of 5 mm, especially 3.0 to 4.2 mm, and the depth is 0.18 to 0.27 mm, especially 0.19 to 0.25 m
m.

As described above, the golf ball of the present invention is formed as a one-piece solid golf ball, a two-piece solid golf ball, or the like. The materials for obtaining these balls and the manufacturing method are known materials and manufacturing methods. be able to. When obtaining a two-piece solid golf ball, it is recommended that the cover has a Shore D hardness of 50 to 70 and a thickness of 1.0 to 3.0 mm from the viewpoint of durability and hitting feeling.

[0024]

The golf ball of the present invention has a good feeling at impact, a sufficiently low trajectory at the time of flight, and a reduction in flight distance. It can be suitably used in an urban golf driving range to be constructed.

[0025]

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

[Examples 1 to 4, Comparative Examples 1 and 2] A rubber base having the composition shown in Table 1 was kneaded with a kneading roll,
One-piece golf balls (Examples 1 and 2 and Comparative Example 1) were obtained by heating and pressing at 25 ° C. for 25 minutes. Further, after kneading the rubber base material shown in Table 1, it was heated and pressed at 155 ° C. for 20 minutes to obtain solid cores (Examples 3, 4 and Comparative Example 2). In Examples 3 and 4 and Comparative Example 2, the obtained solid core was covered with a cover material (Ionomer resin, manufactured by Du Pont-Mitsui Polychemicals, H17).
06 / H1605 = 50/50 blend) to form a two-piece golf ball. Dimples as shown in Tables 2 and 3 were formed on the surfaces of these balls.

Each of the obtained golf balls was evaluated for the feel at impact, the maximum altitude of the trajectory, and the maximum altitude reach by the following methods. Table 3 shows the results. In addition,
In Table 3, the measurement and evaluation of various properties were performed based on the following criteria. Hit feeling ◎: Soft and good ○: Normal ×: Maximum altitude and maximum altitude reach robot with hard trajectory Loft angle 11 with a true temper robot
゜ The trajectory when hit at a head speed of 45 m / s was measured by photography to determine the maximum altitude.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

As is clear from the results shown in Table 3, the golf ball of the present invention has a good hit feeling, a low maximum altitude, a low trajectory, and a sufficient flight distance. It is recognized that there is.

[Brief description of the drawings]

FIG. 1 is an explanatory view (cross-sectional view) illustrating a method of calculating a V ₀ value of a dimple.

FIG. 2 is a perspective view of the same.

FIG. 3 is a sectional view of the same.

[Description of Signs] 1 dimple 2 virtual sphere 3 sphere 4 intersection 5 tangent line 6 intersection 7 dimple edge 8 plane 9 dimple space

Claims (4)

[Claims] 1. A golf ball having a large number of dimples formed on its surface, the weight of the golf ball is 46.5 to 49.0 g, and the deformation of the ball at a constant load of 100 kg is 2.5 to 4.0 mm. And the ratio of the sum of all the dimples of the dimple space volume below the plane surrounded by the edge of each dimple to the total volume of the virtual sphere assuming that there is no dimple on the golf ball surface is 0.7 to 1.1%. A practice golf ball, comprising: 2. A value V _{0 obtained} by dividing a dimple space volume below a plane surrounded by an edge portion of each dimple by a cylinder volume having the above-mentioned plane as a bottom surface and a maximum depth of the dimple from the bottom surface as a height is 0. 2. The composition according to claim 1, wherein the ratio is 40 to 0.65.
A practice golf ball as described. 3. A one-piece golf ball.
Or the practice golf ball of 2. 4. The practice golf ball according to claim 1, which is a two-piece golf ball having a core covered with a cover.