JPS5825180A - Golf ball - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Background of the Invention Various attempts have been made to improve the flight distance of a golf ball for a given impact velocity and momentum within the limits of tradition and operational rules and regulations. Most efforts have focused on the internal structure and structural configuration of the ball, as advances have been made possible by continuous improvements in materials. However, this method
We encountered a somewhat arbitrary set of limits, as the sport's governing body created a rule prohibiting poles that exceeded the maximum. Therefore, for a given compression and compliance, aerodynamic factors and inertia considerations govern.

Previous efforts to improve the properties of golf balls by altering their aerodynamic properties long ago incorporated the distribution of depressions or dimples to improve flight stability.

Subsequently, U.S. Patent No. 4ρ by Martin et al.
No. 90,716, US Pat. No. 1+ to Melvin et al., 1111.559 and Shaw
), extensive research has been done on various surface features, as evidenced by other US Pat. No. 14,142,727. Some of these techniques significantly improve stability based on dimple area distribution or dimple size. The general trend is to use shallow dimples, as are many of these technologies, but only one ball has been provided that uses extremely large and deep dimples. These variations and other types of specialized modifications are used for specific purposes such as improving flight stability, increasing resistance to abrasion and cutting, and facilitating molding. As far as is known to date, patents and other literature do not examine in detail the interrelationships between various aspects of surface topography and their effects on flight distance.

This is because the surface shapes of most golf balls, although clearly designed empirically with a specific purpose in mind, were crude. The golf ball that was hit.

The initial translational speed and rotational speed differ depending on the club used. Both of these speeds, along with the surface geometry, affect aerodynamic lift and drag. The two velocities decrease during flight, and their interrelationship along with their magnitude determines the lift and drag forces at every instant. Additionally, the moment of inertia (and the resulting change in angular velocity) varies depending on the type of ball used, and there is a significant difference in this between the two-piece and three-piece balls currently in widespread use. People also recognize that in real life, they are interested in the composite distance from the tee to the green using two or more clubs, so the optimal flying distance for only one club is not the objective. There is a need to. Since the rotational speed provided by the driver is lower than the rotational speed provided by the lofted club, the aerodynamic response of the golf ball is very different under these two different conditions. The relatively low rotational speed of a ball struck with a driver means that the ball is less affected by aerodynamic factors.

Therefore, under normal conditions with various rubs, achieving the best overall result requires considerable subtlety in arriving at a new aerodynamic surface figure.

(2) SUMMARY OF THE INVENTION Golf balls according to the present invention are constructed such that the total number of dimples, the total volume of surface dimples, and the shape of the individual dimples are kept within objectively determinable limits. 400
Using 250-500 depressions with a total volume of ~700-, each depression is characterized by an arcuate or angular-edged depression near the periphery that increases the individual volume while maintaining the shallow depression shape. It is said that What is the individual volume?

The depth and perimeter of the indentation are normalized to be kept within selected limits by comparison to a reference cone volume related to the perimeter. It was found that when the total volume ■1 is corrected by multiplying by the normalization factor, the resulting value should fall within the range of 700-800-. As a result, the tests showed that the lift-to-force ratio increases without an increase in drag. Balanced to optimally improve composite distance from tee to green, improvements can be seen with both the driver and more lofted clubs.

Further in accordance with the present invention, a normalization criterion for the depression shape is defined in terms of an inscribed cone or other diverging solid having a focal point at the center of the depression base and whose outer edge coincides with the circumference of the depression. The volume of this reference cone 'Iv. Results are obtained for both the binding and dimple volumes iV, with the two-piece and three-piece balls occupying different positions within this range. It is possible to use only the value of Δ as a simplification criterion and leave the other conditions as described above.1
For example, a Δ of 0.75 represents the nominal optimum for a 5 iron. The improved dimple shape can be viewed as a shallow dimple with a peripheral dimple that increases the peripheral volume to the desired extent. Various arcs and straight segments can be used to meet these requirements for the depression.

A better understanding of the invention may be obtained by reference to the description given below in conjunction with the accompanying drawings.

(3. DETAILED DESCRIPTION OF THE INVENTION A golf ball 10 according to the invention is depicted in general form in FIG. Reference should be made to the figures. However, although the golf ball 10 in this example may use between 250 and 500 dimples in accordance with the present invention, a total of 336 dimples or dimples is commonly used.

Furthermore, the total volume of the dimples 12 is 400 to 700 m
d, but the volume chosen preferably varies depending on whether a two-piece or three-piece ball is used. When a low-handicap golfer (e.g., handicap 5 or below) hits a driver, a two-piece pole will have a low rotational speed in the range of 5 to 50 revolutions per second, whereas a two-piece pole will have a rotational speed in the range of 60 revolutions per second. I found out that it does. Therefore, according to the present invention, 500 to 600 for a three-piece ball.
It is preferred to use a total dimple volume (■T) of - and a slightly larger total volume of 530-650+d for two-piece poles.

Below are the hollows 12. The volume of the recess is referred to as ■ and is selected with respect to a number of factors that affect aerodynamic and inertial properties, including the depth of the recess, its shape, and the total recess volume. These factors are the inscribed cone volume V. They are related to each other by an internal reference volume called . This reference volume is the theoretical volume that would be removed by a flared shape with a focal point in the center of the bottom of the depression 12 and a flared edge space with the same extent as the periphery of the depression 12. This cone is
They are usually circular in cross-section, but may also have different curved shapes or polygonal cross-sections. The internal volume represents both the depth and the across dimension of the recess. Therefore,
Two other relations can be defined as follows.

Δ=VD−v.

Referring to Figure 2, the depth h of the depression (which is also the inverse of the height of the depression seen from the center of the bottom) and the constant radius rt
The reference volume is defined by the outer periphery having k according to the following formula.

The total volume VD of the individual depressions or dimples is measured,
It can be determined by calculation or approximate calculation. Second
In the case of a truncated spherical dimple with benthic diameter rxk in the truncated plane as shown in the figure, the volume calculation formula is VD = 77rh (3(rI) + 3 (rz) +h
It is J.

According to the present invention, the differential volume whose relationship to the reference volume falls within a certain range and has an allowable total volume improves the net aerodynamic properties of the golf ball by a factor of 9, resulting in a greater A series of tests have shown that it gives a composite distance from the tee to the green. The actual total volume vT is modified by the standardization factor l. The relationship to be observed is that for a three-piece golf ball according to the U.S. standard, Δ It must be within the range.

Δ ■T (ding) -750-±100- The maximum value of the distance to the driver is obtained when a three-piece ball is 700-±50-, and when only a 5-iron is used, the value is 800 ad±50- It was also found that In the case of a two-piece pole, the base values are somewhat more specific because the rotational speed and moment of inertia are slightly lower, and a slightly larger normalized recess volume should be used. Similarly, if low rotation is primarily of interest, a larger recess volume may be used. However, even in the case of these variations, the normalized indentation volume will be within the ranges mentioned above. Furthermore, since one must be primarily interested in the composite response characteristics to using clubs of various lofts, the driver and 5-iron combination provides the best way to characterize the use of a range of clubs.

Referring to FIG. 2, two examples of shallow depressions with peripheral edge depressions according to the present invention are as follows.

Table 1 VD 1.546*yl 1.608vrdVC0
,83511d 0.858adΔ 0.71
1id o, 77i+4R'0.54 0.52 rl ill! 4+n 1.77mrg,,
0.879m 0.93m Deimpuno Ishio 3
36 336VT 519
mil 540-h 0.2
37■ 0.256mΔ TR6g31111 799114 These configurations clearly do not impose any unconventional requirements on either ball construction or user acceptance. However, as pointed out below, it is important to note that it is not only the shape of the shallow indentations that provides the desired overall result, but also the total indentation volume and the total number of indentations.

In contrast, conventional configurations were either high or low outside the prescribed range for normalized indentation volume. Referring to the third factor, most of the conventional ball shapes currently in use typically have 322 to 556 dimples, but the normalized dimple volume is too low.

“Wilson” belongs to the higher end of this lower range.
Although the Pro Staff has dimples that can be thought of as truncated cones, most ball constructions simply use spherical arcs, but in a different way.

At the opposite end of the normalized indentation volume is given by a royal ball with a small number of very large spherical dimples giving a normalized indentation volume of 1000-.

However, according to the present invention, the normalized indentation volume for a three-piece ball peaks within 750 ad for the driver and 5-iron combination. Referring to FIG. 4, the peak is in the 800 md range for the normalized indentation volume for the 5 iron only. Referring to FIG. 5, in the case of only the driver, 71
It is in the range of 0-.

At the extremes of these ranges the flight distance response levels off. The tests were performed under standardized conditions and analyzed statistically, and the curves are ±1 for this reason.
．． It is understood to be accurate at 4 m (1,5 yards). Any golfer will attest that the resulting improved response is significantly advantageous.

The profound effect that this particular shape of the dimple geometry has on aerodynamic properties appears to arise from the fact that although it positively affects lift, it does not result in a comparable increase in drag. A mathematical solution may be possible, but it is extremely complex and beyond the immediate scope. Although the interaction is not completely understood, it is believed that the benefits of the graphics according to the invention are realized in the pre-apex and apex portions of the flight, rather than in the initial portion of the flight. The initial forward velocity of a ball for a given configuration will be the same for the same strike regardless of the dimple pattern. Although the initial rotational speed will be the same, the effects of lift and drag will differ depending on the shape of the cavity and the total volume of the cavity. Drag forces immediately begin to slow down the rotational speed, but lift forces have no substantial effect until the translational speed has slowed down somewhat. The moment of inertia is greater for a three-piece ball than for a two-piece ball, but this also has an adverse effect on reducing rotational speed. Therefore, the extra indentation around the periphery of the indentation can increase lift with little increase in drag, or can both increase lift and decrease drag. However, these conditions are only true if the other parameters, namely the total number of dimples and the total dimple volume, are within the aforementioned ranges. Of course, both the lift and drag forces change as the translational and rotational speeds decrease.

However, the effect on the ball is clearly visible, as the ball hit with a lofted iron will rise to the top of its flight before beginning its steep downward descent. Therefore, the greatest benefits are seen in the middle of the flight and in the pre- and apex portions of the flight.

Δ normalization factor must be greater than 1, preferably 1
．． Should be greater than or equal to 1. This places further constraints on the size and shape of the depression. Furthermore, as shown in FIG. 6, C can be obtained which shows that there is a significant direct relationship between the difference Δ and the carry distance. FIG. 6 shows the change in carry distance for a golf ball hit with a 5-iron and shows that the maximum distance is achieved with a Δ value of 0.5- for a three-piece ball. The test results for the two-piece configuration appear to show the same optimum i, but no test points were taken near Δ-0, 75- for the two-piece ball. The equation provides a basis for writing how the carry distance falls in contrast for values of Δ higher and lower than 0.751111, and the change is about ±0.20 from the reference value of 0.75. It shows that it extends almost in a straight line up to the point.

Within the parameters previously defined, the depression shape may be arcuate, as shown in FIG. 2, or it may be a series of cones that merge into the bottom of the depression.

Furthermore, the dimples do not have to have a circular periphery; polygonal dimples also satisfy the requirements, as do cylindrical dimples whose bottom corners may be rounded.

Although various forms of construction of a golf ball according to the invention have been shown and described in the drawings, the invention is not limited thereto, but is contemplated to include all forms and variations that fall within the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is an illustration of a golf ball according to the present invention 1 in which the dimples are not to scale and the specific shape of the dimples is not apparent. FIG. 2 is an enlarged side cross-sectional view of the golf ball segment of FIG. 1, showing the nature of the curvature of the indentation and the internal reference for the shape of the normalizing cone, and Δ FIG. Graph of composite distance for pigeon middle irons, FΔ Figure 4 is a graph of distance vs. VT (T) value for middle irons, Δ Figure 5 is a graph of driver distance vs. VT (T), Figure 6 is a graph of distance for middle irons vs. VT (T). The distance vs. Δ is the only variable 10--golf ball, 12--(indentation or dimple. FIG, 2 FIG, 3) νT (threat) day G, 6 11.0-o, nl

Claims (1)

[Claims] 1. A spherical surface with 250 to 500 dimples, each dimple having a rim indentation that increases the dimple volume without increasing the dimple depth, and the total indentation volume of said dimples being 1100 to 700 zd. In the range, VD is the volume of the individual dimple, and V
A golf bowl having a surface figure in which C is the internal volume of a diverging solid whose focal point is at the center of the bottom of the dimple and whose end of the divergence coincides in contour with the periphery of the dimple. 2. The golf ball according to claim 1, wherein the value of Δ is 1.1 or more. If the value of Δ 3, +1.0--1 is smaller than 020, then 0.
75. The golf ball according to claim 2, characterized in that: