JP2751601B2 - Golf ball - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball having improved flight characteristics and improved flight characteristics by improving aerodynamic symmetry by improving a dimple arrangement. About the ball.

2. Description of the Related Art The role of dimples in a golf ball is to promote a transition from a laminar flow to a turbulent flow in a boundary layer near the surface of the golf ball caused by the movement and rotation of the golf ball, and the separation point Is shifted rearward, thereby reducing the pressure resistance and further obtaining the lift from the difference in the separation point between the upper and lower sides of the golf ball. Therefore, the trajectory of the golf ball changes depending on the shape and arrangement of the dimples, and this trajectory greatly affects the flight distance of the golf ball.

For this reason, it is desired to develop dimple shapes and arrangements that provide an effective trajectory for increasing the flight distance.

On the other hand, golf balls are required to have aerodynamic symmetry specified by the attached rule III ball (C) of the Rules of the Japan Golf Association. In other words, it is required that the flight distance and the trajectory have no difference regardless of where the ball is hit.

Conventionally, commercially available golf balls can be said to be balls having aerodynamic symmetry within the range specified in the above rules, but there are some differences in flight distance and trajectory depending on the hitting position of the ball It is. When using a slightly, but aerodynamically asymmetrical ball, this asymmetry can lead to shot instability, especially at the level of advanced and professional golfers.

The cause of the aerodynamic asymmetry of a golf ball is the presence of a seam line. This is because when manufacturing a golf ball, compression molding is performed using two molds each having a hemispherical molding surface, so that dimples formed on the combined buds of the molds do not cross each other. Is a circle,
Golf balls are inevitably present in their production.

Here, in the above rule III ball (C), as shown in FIGS. 6A and 6B, two opposing points c and c on the seam line b of the golf ball a and the center d When the ball a is hit f so as to generate a backspin having a straight line e connecting the three points as a rotation axis (FIG. A), it is orthogonal to a circular plane g having a seam line b of the ball a as a circumferential line, and When the ball a is hit i so as to generate a backspin around the straight line h passing through the center d of the ball a (B
Aerodynamic symmetry based on differences in flight distance, peak angle (angle of a straight line connecting the highest point of the ball and the hitting point with respect to a horizontal line), and flight time. The striking method shown in the drawing is called a pole striking, and the striking method shown in the drawing B is called a seam striking.
When such a ball hitting test is performed on a golf ball having a seam line as described above, it is known that the trajectory of the ball hit by the pole has a larger peak angle than the trajectory of the ball hit by the seam, For this reason, the flight distance and flight time also change.

Therefore, it has been proposed to form a large number of great circles on the ball surface similar to those of the seam line where no dimples intersect to improve the aerodynamic symmetry of the ball. For example, the ball surface is divided into 20 triangles as a regular icosahedron,
One example is a so-called icosahedral arrangement in which dimples are arranged, and various geometrically high uniformity balls have been proposed.

However, at present, there is still room for improvement even in a golf ball having such a high geometric uniformity.

The present invention has been made in view of the above circumstances, and by improving the dimple arrangement, improves aerodynamic symmetry, shows stable flight characteristics, and shows a golf trajectory that is effective in increasing the flight distance. Aim to provide the ball.

Means for Solving the Problems In order to achieve the above object, the present invention draws one first virtual great circle on the ball surface, and further comprises three second virtual great circles orthogonal to the first virtual great circle. The intersection of the virtual great circle line and the first virtual great circle line is drawn so as to divide this first virtual great circle line into six equal parts, and the two ball surfaces having a length of 1/4 of the great circle length are formed on the ball surface. Equally divided into 12 spherical isosceles triangles consisting of the long side and one short side having a length of 1/6 of the great circle, and dimple arrangement in one spherical isosceles triangle on the ball surface And the dimple array in the other two spherical isosceles triangles adjacent to each other on the two long sides of the spherical isosceles triangle becomes a line symmetry with the long sides shared with each other as axes of symmetry, and the spherical isosceles The dimple arrangement in another spherical isosceles triangle adjacent to the short side of the triangle is located at the midpoint of the short side shared with each other. That the dimples are arranged so as to be symmetrical and that the dimples do not intersect on the first virtual great circle line and that the centers of at least one dimple intersect on the three second virtual great circle lines. A golf ball is provided.

Hereinafter, the configuration of the golf ball of the present invention will be described in more detail with reference to the drawings.

As shown in FIG. 1, the golf ball of the present invention first draws a first virtual great circle 2 on the surface of the ball 1, and further makes three second virtual great circles orthogonal to the great circle 2. The circles 3, 3, 3 are so divided as to make six intersections 3a, 3b, 3c,... (Three not shown) with each great circle 2 divide the first virtual great circle 2 into six equal parts. The surface of the ball 1 is composed of two long sides 4a and 4b having a length of 1/4 of the great circle 3 and a short side 5 having a length of 1/6 of the great circle 2. 12 spherical isosceles triangles I, II, III…
XII (XI and XII are not shown) is equally divided.

Next, dimples are uniformly arranged on the surface of the ball 1. In this case, as illustrated in FIG. 2, the dimple arrangement in one spherical isosceles triangle I is equal to 2 of this isosceles triangle I. The two long sides 4a and 4b are adjacent to each other and the dimple arrangement in the other two spherical isosceles triangles II and VI are line-symmetric with respect to the long sides 4a and 4b that are shared with each other. The dimple arrangement in the spherical isosceles triangle VII adjacent to the short side 5 of the triangle I and the two isosceles triangles I
And the point is symmetrical with respect to the midpoint 6 of the common short side 5, and no dimples intersect on the first virtual great circle line 2 and there are no dimples on the second virtual great circle line 3, 3. The dimples are arranged such that at least one dimple crosses at the center.

That is, in FIG. 2, the dimples Ia, Ib, Ic and the semicircle dimple Id, Ie in the isosceles triangle I are respectively the dimples IIa, IIb, IIc and the dimples in the isosceles triangle II. It has the same shape as the semicircular dimples II d and II e, and is arranged at a line symmetric position with the shared long side 4 a as the axis of symmetry,
Similarly, the dimples VI a, VI b, VI in the isosceles triangle VI
c and the semicircular dimples VI d and VI e (VI c is not shown) have the same shape and are located at line-symmetric positions with the long side 4b as the axis of symmetry. Furthermore, these dimples Ia, Ib, Ic and semicircular dimples Id, Ie are dimples in an isosceles triangle VII.
VIIa, VIIb, VIIc and semicircular dimples VIId, VIIe (VI
Ia, VIIb, VIIc are not shown) and have the same shape as
In addition, they are arranged at point-symmetric positions with respect to the middle point 6 of the common short side 5. In addition, one dimple does not intersect on the first virtual great circle line 2, while dimples straddling two isosceles triangles on the second virtual great circle line 3, 3, 3 respectively (for example, Semicircular dimples I d and I in isosceles triangles I and II
A dimple d) consisting of I d intersects at its center. The first virtual great circle line 2 where the dimples do not intersect
Can be a seam line formed in the manufacture of a golf ball, and there are no dimples crossing other than at the center on the second virtual great circle lines 3, 3, 3.

Here, an isosceles triangle I is specified as one spherical isosceles triangle, and three isosceles triangles adjacent thereto are specified.
Although the relationship between II, VI and VII has been described, this golf ball 1 has dimples arranged so as to have the same dimple arrangement as described above regardless of which spherical isosceles triangle on the surface is specified. is there.

Further, the golf ball has only a very small number of dimples for convenience of explanation, but actually has more dimples. In particular,
Although not particularly limited, 360 to 460, particularly 390
Up to 440 dimples are suitably arranged.

Further, the types of dimples may be one or more, but it is particularly preferable that three types of dimples having different diameters and depths are uniformly arranged on the ball surface.
At this time, although not particularly limited, the largest dimple has a diameter of 3.9 to 4.2 mm, a depth of 0.17 to 0.21 mm, the middle dimple has a diameter of 3.3 to 3.7 mm, a depth of 0.15 to 0.19 mm, and the smallest dimple has a diameter of 2.4. It is preferable that the thickness is about 3.2 mm and the depth is 0.08 to 0.15 mm.

When a plurality of types of dimples are provided in this manner, the number of types of dimples is n, and the diameter of each type of dimple is
D _m k, when the depth was set to Nk D _p k, the number (where, k = 1, 2,
3 ... n), the following formula (1) (Where R is the ball radius, and Vo is the volume of the dimple below the plane surrounded by the edge of the dimple k, the volume of which is a cylinder whose height is the maximum depth of the dimple k from this bottom. Divided value (JP-A-60-166367)
And Nk is the number of dimples k. By setting the dimple total surface area index (Dst) of 4 or more to 4 or more, more excellent increase in flight distance and improvement in aerodynamic symmetry are exhibited. Furthermore, the average of all dimples of the value Vo obtained by dividing the dimple space volume under the plane surrounded by the edge of the dimple by the above-mentioned plane as a bottom surface and dividing the maximum depth of the dimple from the bottom surface by a cylinder volume as a height Vo is 0.4 to 0.4. It is preferably 0.52, especially 0.45 to 0.5.

Specifically, the arrangement shown in FIGS. 3 and 4 can be exemplified as the dimple arrangement of the golf ball of the present invention. That is, Fig. 3 shows that the Vo value is 4.05mm in diameter and 0.18mm in depth.
With a maximum of 204 dimples of 0.47, a diameter of 3.50 mm and a depth of 0.17 mm
Vo value is 0.47, medium dimple 168, diameter 2.50mm, depth 0.12
In this example, 48 minimum dimples having mm and Vo value of 0.47 are arranged according to the present invention, and Dst is 4.43. Also, the third
The figure shows 144 dimples with a diameter of 4.00 mm, depth of 0.19 mm and a Vo value of 0.47, 144 dimples with a diameter of 3.60 mm, depth of 0.18 mm and a Vo value of 0.47, and 216 medium dimples with a diameter of 2.45 mm and a depth of 0.13 mm. An example in which 60 minimum dimples with a value of 0.47 are arranged according to the present invention,
Dst is for 4.24.

The golf ball of the present invention is a one-piece ball,
The golf ball may be a solid golf ball such as a two-piece ball or a thread-wound golf ball, and its production method may be an ordinary method.

Effect The golf ball of the present invention has the above-described dimple arrangement, thereby improving aerodynamic symmetry and allowing a difference in a flight distance and a trajectory caused by a different hitting point of the ball, that is, a difference in the rotation axis of the back spin. Can be reduced as much as possible,
Therefore, it always shows stable flight characteristics and shows an effective trajectory for increasing the flight distance.

Effects of the Invention As described above, the golf ball of the present invention has improved aerodynamic symmetry by improving the arrangement of dimples, exhibits stable flight characteristics, and is effective in increasing the flight distance. It has a good trajectory and a good flight distance.

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

[Examples and Comparative Examples] Three types of two-piece golf balls having dimples having the properties shown in Table 1 were produced. Except for the properties of the dimples, all had the same configuration.

The following tests were conducted and investigated on the flight characteristics of these golf balls.

True Temper for each ball
Pole and seam strikes are performed 24 times at a head speed of 45 m / sec using a company's impact robot, carry (flight distance) total distance (carry + run), peak angle (appearance of the trajectory observed from the strike point) height)
Was measured, and the average value of 24 measurements was taken as the final measured value. The symmetry of each ball was evaluated for each measurement item, and the flight characteristics were considered. Table 2 shows the measured values.

As can be seen from the results shown in Table 2, the golf ball of the comparative example does not necessarily have a bad symmetry in carry, but the symmetry in the total distance is equal to that of the golf ball of the present invention (Examples 1 and 2). Significantly inferior. This is because the trajectory of the golf ball of this comparative example by hitting the pole has a high peak angle, as shown in the difference in the peak angle. This is caused by a small amount. This means that the flight characteristics (such as trajectory) due to the dimple arrangement are poor, which means that the flight distance is reduced. In other words, the difference in trajectory between seam hitting and pole hitting means that the flight distance is sometimes large and the flight distance is sometimes small, which reduces the absolute non-distance of the ball. become. Further, such a ball has poor flight stability and is difficult to handle.

In contrast, the golf balls of the present invention (Examples 1 and 2) have excellent aerodynamic symmetry, exhibit stable flight characteristics, and exhibit an effective trajectory for increasing the flight distance.

[Brief description of the drawings]

1 and 2 are explanatory views for explaining the dimple arrangement of the golf ball of the present invention, FIGS. 3 and 4 are plan views each showing an embodiment of the present invention, and FIG. 5 is a golf ball of a comparative example. FIGS. 6 (A) and 6 (B) are plan views showing a ball and are explanatory diagrams for explaining a method of evaluating aerodynamic symmetry. 1 golf ball 2 first virtual great circle line 3,3,3 second virtual great circle line 4a, 4b long side 5 short side 6 midpoint I to XII ...... spherical isosceles triangle

Claims (1)

(57) [Claims] 1. A first virtual great circle line is drawn on the ball surface, and three second virtual great circle lines orthogonal to the first virtual great circle line are connected to the first virtual great circle line. The intersection is drawn so as to divide this first virtual great circle line into six equal parts, and the ball surface has two long sides having a length of 1/4 of the great circle length and a length of 1/6 of the great circle length. The ball is equally divided into 12 spherical isosceles triangles each having one short side, and a dimple arrangement in one spherical isosceles triangle is formed on the ball surface by two long sides of the spherical isosceles triangle. The dimple arrangement in the other two spherical isosceles triangles adjacent to the sphere becomes axisymmetric with the long side shared by each as the symmetry axis, and the other spherical isosceles triangle adjacent to the short side of the spherical isosceles triangle. The dimple arrangement in the equilateral triangle is point-symmetrical with respect to the midpoint of the short side shared by both sides. Sample is not cross, and the 3
A golf ball, wherein dimples are arranged on the second virtual great circle line of the book such that the centers of at least one dimple intersect.