JPS6336267B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a golf ball having a dimple arrangement uniformly formed on the ball surface. Conventionally, in the production of golf balls, dimples have been determined mainly empirically and experimentally. Recently, the pitch between the centers of dimples, diameter, shape,
Various efforts have been made to determine parameters related to dimples, such as depth. For example, in JP-A-53-115330, the depth of dimples and the center-to-center pitch of dimples are determined experimentally regarding the adoption of a new material for the cover of a golf ball. Conventionally, there is no perfect arrangement of dimples, and the arrangement method based on the rhombic cuboctahedron (Fig. 7), which was considered to be better than others, has been empirically adopted, and most of them are A total of 336 dimples are arranged, 16 on the square sides and 6 on the triangular sides (Figure 8). Of course, as seen in JP-A-19325-1972 and JP-A-50-8630, there is a method of placing a predetermined number of dimples on the spherical triangle of the ball surface based on the regular icosahedron, and the method of arranging a predetermined number of dimples on the spherical triangle of the ball surface, There are methods such as 115330 in which dimples are arranged along concentric circles drawn at equal intervals on a spherical surface, and methods based on dodecahedrons. According to each of the above-mentioned arrangement methods, the distribution of dimples is close to a uniform arrangement, but even so, in the rhombic cuboctahedral method (Figure 8), the pitch between dimple centers is up to 18% in the case without brand space. A difference of up to 15% is observed in the sequence shown in the above-mentioned Japanese Patent Application Laid-open No. 48-19325. Therefore, these differences inevitably cause the directionality of the array. For example, in Figure 8, the respective arrays with respect to the vertical axis and the axis forming 45 degrees to this have directionality with respect to each other, and any arbitrary point penetrating the ball Regarding the rotating shaft, there was a problem that the dimples did not appear uniformly. The present invention provides a dimple arrangement in which the pitch difference between the dimple centers is zero, and therefore the dimples appear uniformly with respect to any rotational axis. An embodiment of the present invention will be described in detail below with reference to the drawings. The shortest distance connecting two points on any spherical surface is called a geodesic line, and it lies on the great circle connecting the two points.Since it is the shortest distance, it is on the inferior arc side of the great circle, and is the basic route for airplanes and ships. is well known. By the way, a spherical polyhedron whose edges are all geodesic lines is called a geodesic polyhedron. For example, the figure on the spherical surface that is created by projecting from the center of the sphere onto a sphere circumscribing a regular icosahedron is a spherical regular icosahedron in which all edges 4 are geodesic lines, and is a geodesic regular icosahedron (Figure 4). ). The present invention is directly related to the subdivision of geodesic icosahedrons. The following method is available for dividing a geodesic icosahedron into one. In Figure 5, the geodesic positive 20 indicated by the broken line
A curve that vertically bisects each edge 4 of the face piece, for example, a curve 5
By extending 0, the vertices 51 of the icosahedron,
Reach 52. Similarly, for all remaining edges, draw perpendicular bisector curves ending at the nearest vertex of the icosahedron (Figure 5). As a result, the geodesic regular icosahedron was divided into 60 hexahedrons.
It is called a two-frequency triangular triacon division of an icosahedron. Frequency is the number of equal divisions of the edge, and the triangular shape is so called because the shape created by division is a spherical triangle. Next, the edges of the geodesic icosahedron shown by the broken lines are 4
The resulting geodesic icosahedron 4-frequency triangular triacon division is shown in Figure 6. In addition to the pattern shown in FIG. 5, in FIG. 6, great circles 64, 65, and 66 perpendicular to the edge passing through the 1/4 dividing point 61, 2/4 dividing point, and 3/4 dividing point 63 of the edge are shown. When drawn, each great circle passes through the 1/4, 2/4, or 3/4 dividing points of the other edges. Similarly, all other edges are great circles and are divided into 240 faces. Further ridge 8
If you divide it into equal parts and draw a great circle perpendicular to the edge through each division point of 2/8, 4/8, and 6/8 in Figure 6 for all edges, it will be divided into 960 planes as shown in Figure 3. The resulting figure is obtained. The figure shows the geodesic icosahedron divided into 8 frequency triangular triacons. In FIG. 3, the center of the dimple 1 is placed at two vertices 3, 3 of the triacon-divided spherical triangle, and the remaining one apex 31 is left as is and nothing is placed. The part where dimples are not placed is called hill 2. To describe the arrangement method of this embodiment in more detail, the center point of the figure shown in FIG. Place the dimple center at the apex. If the arrangement is continued and completed according to the above-mentioned rules using the above as a reference, the dimple arrangement shown in FIG. 1 will be obtained. The dimples are drawn with the vertex of the spherical triangle as the center and the radius is 40 to 50% of the length of the ridge, so the dimples are drawn close to each other. In FIG. 1, the number of dimples is 320. When the radius of the dimple is 1/2 of the edge, circular dimples 1 of the same diameter are adjacent to each other and there is no overlap or gap, so it can be understood that the pitches between the centers of all adjacent dimples are equal. That is, the pitch between the dimple centers is the same for all dimples, and the pitch difference is 0. In order to understand the dimple arrangement of the present invention, it is recommended to refer to the dimple center connection diagram (FIG. 2) in which the dimple centers are connected. In Figure 2, the pitch between dimple centers is
It is given by 0.0875×D, and the pitch difference between the dimple centers is 0 as described above. However, D is the diameter of the golf ball without the dimple 1, that is, the diameter of the ball at the hill 2 portion. Further, the distances between the center of dimple 1 and the center of hill 2 are the same within a difference of 10%. The difference in distance between the center of dimple 1 and the center of hill 2 varies because, as can be seen in Figure 2, the spherical regular polygon formed by connecting the centers of dimple 1 is mostly spherical regular 6 This is because although it is a polygon 6, a spherical regular pentagon 5 is included in a part. Therefore, there are two types of distance between the center of the dimple 1 and the center of the hill 2: one related to the spherical regular hexagon 6 and the other related to the spherical regular pentagon 5, and the former is 10% longer than the latter. The center of the spherical regular pentagon 5 is the geodesic regular
It coincides with the vertices of the icosahedron. Therefore, there are 12 spherical regular pentagons 5, which are perfectly evenly arranged on the spherical surface and are not offset. The purpose of the dimple is to create turbulence through backspin, keep the ball in stable flight, and extend the carry. Therefore, it is desirable that the dimple arrangement be equivalent with respect to any rotational axis, that is, the appearance of the dimples and hills should be equivalent with respect to any rotational axis. In this respect, the dimple arrangement of the present invention can be said to be close to ideal, as the pitch difference between dimple centers is 0 as described above, and the distances between the dimple centers and the centers of the hills match within a difference of 10%. I can do things.
The stable generation of turbulent flow due to back spin to extend the carry and the backward movement of the separation point at the bottom of the ball affect not only the pitch between the dimple centers mentioned above but also the shape, size, and depth of the dimples. be done. As described above, the object of the present invention is to provide a dimple arrangement in which the pitch difference between the dimple centers is zero. Therefore, the shape and major axis of the dimple 1 shown in FIG. The shape and diameter are not limited to those shown in FIG. 2, but various changes can be made in order to extend the carry, and increasing or decreasing the diameter can be done according to the present invention as well as changing the depth of the dimples. is within the range of In the present invention, the frequency is not limited to 8, but other values (even numbers) can be used. That is, the frequency of the present invention is any of the even numbers N. It is obvious that the present invention is applicable to all golf balls including thread-wound balata balls, thread-wound Surlyn balls, two-layer solid balls, and one-layer solid balls. The table below shows a comparison of the flight characteristics of balls of Examples of the present invention and Comparative Examples. Comparative Example 1 is a graph on the surface of a sphere that is virtually partitioned by lines formed by projecting the edges of a regular octahedron whose vertices are on the surface of the sphere.
The same dimple arrangement within each of the 12 areas. Comparative Example 2 has the same dimple arrangement in each area projected onto a regular dodecahedral sphere using the same method as Comparative Example 1. However, the dimples have different diameters and depths4.
The diameter and depth of the dimples are the average value (Japanese Patent Application Laid-Open No. 1972-
No. 32730). Comparative Example 3 uses the same method as Comparative Example 1 to arrange dimples in roughly the same pattern within each area of a regular icosahedron projected onto a sphere (Japanese Patent Application Laid-open No. 8630/1983). In Comparative Example 4, dimples were arranged in roughly the same pattern in each area of a regular icosahedron projected onto a sphere using the same method as Comparative Example 1 (Japanese Patent Laid-Open No. 49-52029).

[Table] As described above, the carry of a golf ball depends on the above-mentioned parameter group related to dimples, but the present invention provides an ideal arrangement in which the pitch difference between dimple centers is one of the parameters, and the pitch difference is zero. In addition to extending the carry, the dimple arrangement of the present invention is close to the ideal arrangement in experiments to determine the optimal conditions for the carry, and there is no need to experiment with the dimple arrangement, and it is sufficient to experiment with other parameters, reducing the number of experiments. This is an excellent invention that can reduce the amount of

[Brief explanation of the drawing]

FIG. 1 is a front view of a golf ball with a dimple arrangement according to the present invention. Figure 2 is a front view of the dimple center connection diagram in Figure 1, and Figure 3 is the geodesic correct view.
Figure 4 is a front view of a geodesic regular icosahedron divided into 8 frequency triangular triacons. Figure 5 is a front view of a geodesic regular icosahedron divided into 2 frequency triangular triacon.
The figure shows a front view of a geodesic regular icosahedron divided into 4-frequency triangular triacons, Figure 7 is a front view of a conventional rhombic cubic octahedral sphere, and Figure 8 shows the dimple arrangement of a rhombic cubic octahedral sphere. front view. 1... dimple, 2... hill, 3... vertex where dimple is placed, 4... vertex where nothing is placed, 5
... Spherical regular pentagon, 6... Spherical regular hexagon.

Claims (1)

[Claims] 1. Divide the virtual sphere into geodesic regular icosahedrons,
Further, it is divided into N (N is an even number) frequency/triangular triacon, and the center of the dimple is placed at two vertices of the entire spherical triangle created by the above division, and no dimple is placed at the remaining one vertex. Golf ball. 2. The golf ball according to claim 1, wherein the N is an even number from 2 to 10. 3. The golf ball according to claim 2, wherein the N is 8. 4 Dimple diameter is 80% of the pitch between dimples
100%.