JPH11178952A - Method for determining bending point of golf club, golf club shaft with features expressed by the method, and golf club equipped with the golf club shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To match measured characteristics of a golf club with a feeling in a swing by judging characteristics including bending point of the shaft by curvature distribution calculated from data of measurement of the distribution of bending moment loaded on a shaft in a swing and bending rigidity distribution. SOLUTION: The grip side of a shaft 2 is fixed by a fixing part 11. Bending moment is applied loaded on the tip end part of the shaft 2 by a torque sensor 12. A laser sizer 13 is moved from a measuring part 11 side to the tip end side. A flexure curve and an outer shape Dere measured and inputted into CPU. A load is inputted from the torque sensor 12. Then the flexure curve of the shaft center axis is calculated. CPU circular-approximates by the least square method to calcualte the curvature radius on which binding moment acts and the center to calculate the curvature distribution. CPU also calculates the bending moment from the load and the distance from the load to complete. The CPU calculates the bending rigidity distribution of the shaft 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the condition of a golf club shaft, a golf shaft characterized by the characteristics expressed by the method, and a golf club equipped with the shaft, and more particularly to a golf club shaft. The present invention relates to a method, a golf shaft and a golf club, in which a distribution of a bending moment is measured and a condition of a shaft is determined based on a curvature distribution obtained from a bending rigidity distribution.

[0002]

2. Description of the Related Art In general, it is one of important matters that a golf club has a performance of accurately hitting a hit ball farther to a target position. Here, attention is paid to the behavior of the golf shaft during the swing. From the address to the impact, the shaft reaches the impact by bending and twisting unique to each golfer, and the impact portion is transformed into various forms. Of particular importance is the ability of the club head to move just before impact and achieve the correct impact, not to mention that the role of the shaft is of utmost importance, especially the flex and tone of the shaft. Such characteristics cannot be neglected.

[0003] Conventionally, golf shafts are referred to as a first tone, a middle tone, and a hand tone, respectively, based on the difference in the bending of the shaft (which part on the tip side, the center, and the grip side is better). In addition, there are several determination methods, all of which involve applying a static bending moment and measuring and evaluating the bending of the shaft.

The most typical conventional determination method is to fix the grip side of the shaft and to bend the shaft tip when a load is applied to the tip (hereinafter, abbreviated as Tip def).
Conversely, the smaller the value of the ratio “Tip def / Butt def” of the amount of deflection of the grip portion (hereinafter abbreviated as Butt def) when a load is applied to the grip portion while fixing the tip of the shaft, the smaller the value Condition. " In addition, there is a place where the condition is determined by using these values by a similar method other than the above.

As another typical example of the conventional determination method, a static buckling load is applied to the shaft from both the tip and the grip side of the shaft, and the peak position of the bent curve is close to the tip of the shaft. There are also places where judgment is made from the front condition to the hand condition depending on the proximity to the grip side.

Further, as still another example of the conventional judging method, a bending curve at that time is measured in a state where a static load is applied to the shaft in the same manner as in the above two examples, and each position is measured. There are also places where the condition of the shaft is determined from the curvature of the shaft.

[0007]

FIG. 4 shows a typical steel shaft [: S1] which is the background of the present invention and to which the present invention is applied, and a unique carbon fiber reinforced plastic shaft (hereinafter abbreviated as CFRP shaft). FIG. 7 is a diagram showing the outer diameter and bending rigidity distribution of FIG.

In the above-mentioned conventional first typical measuring method, the outer diameter gradually increases from the tip of the shaft to the grip portion, as in a typical steel shaft shown in FIG. In the design where the thickness becomes small, the value of “Tip def / Butt def” expresses the characteristic of the difference of the front rigidity distribution of the shaft, though it is indirect in the shaft where the bending rigidity distribution gradually increases. Did not.

However, in recent CFRP shafts, as shown in FIG. 24, combinations of carbon fibers having different elastic moduli, fiber orientation angles (angles formed by carbon fibers with respect to the shaft length direction; straight layer, bias Various designs are possible, such as changing the number of layers partially and the number of laminations, and examples of unique CFRP shafts as shown in FIG. 4 have come to be seen. As a result, it is difficult to express the characteristics of the shaft in the condition determination method as in the three conventional examples described above, and the performance such as the “condition” measured by the shaft itself and the “ There has been a problem that the performance such as "tone" may be felt as a feeling or may not match the sensory to be evaluated.

[0010] Therefore, a main object of the present invention is to make it possible to match the performance such as the condition measured on the shaft itself with the sensation that the golfer feels or evaluates the condition such as the condition of the shaft when swinging. It is an object of the present invention to provide a method of determining the condition of a golf club shaft, a golf shaft characterized by characteristics expressed by the method, and a golf club equipped with the shaft.

[0011]

Means for Solving the Problems Claims 1, 8 and 15
The invention according to the invention measures the distribution of the bending moment applied to the shaft of the golf club during the swing from the address to the impact, determines the characteristics including the tone of the shaft from the data and the curvature distribution obtained from the bending rigidity distribution of the shaft, Consisting of a golf shaft expressed by those characteristics and a golf club equipped with such a golf shaft, the performance including the tone measured by the shaft itself, and the golfer feels as a feeling during a swing,
The sensory to be evaluated can be matched.

The invention according to claims 2, 9 and 16 measures the distribution of the bending moment applied to the shaft during the swing from the address to the impact. In particular, the distribution of the bending moment in the swing direction applied to the shaft immediately before the impact is measured. Measure the rate of change, determine the characteristics including the condition of the shaft from the rate of change of the curvature distribution obtained from the data and the bending rigidity distribution of the shaft, and configure the shaft with such a condition and a golf club equipped with such a shaft. Is done.

The invention according to claims 3, 10 and 17 is
Measure the distribution of the bending moment applied to the shaft during the swing from the address to the impact, especially measure the rate of change of the distribution of the bending moment in the swing direction applied to the shaft immediately before the impact, and use the data and the bending rigidity distribution of the shaft The characteristic including the condition of the shaft is determined from the ratio (area ratio) of each part of the change rate of the curvature distribution obtained,
A golf shaft is constituted by such a condition, and a golf club is constituted by including such a golf shaft.

The invention according to claims 4, 11 and 18 is
Measures the distribution of the bending moment applied to the shaft during the swing from address to impact, measures the rate of change of the distribution of the bending moment in the swing direction applied to the shaft immediately before the impact, and obtains it from the data and the bending stiffness distribution of the shaft. In the rate of change of the curvature distribution, the characteristics including the tone of the shaft are determined from the ratio (area ratio) of each of the equally divided portions in the shaft portion excluding the portion corresponding to the neck portion and the grip portion of the club head. A golf shaft is constituted by a simple shaft, and a golf club is constituted by including such a golf shaft.

The invention according to claims 5, 12 and 19 is:
Measure the distribution of the bending moment applied to the shaft during the swing from the address to the impact, especially measure the rate of change of the distribution of the bending moment in the swing direction applied to the shaft immediately before the impact, and use the data and the bending rigidity distribution of the shaft A characteristic including the condition of the shaft is determined from the position of the peak of the rate of change in the curvature distribution obtained, and a golf shaft is formed with the shaft having such condition, and a golf club having such a golf shaft is formed.

The invention according to claims 6, 13 and 20 is as follows:
Measure the distribution of the bending moment applied to the shaft during the swing from the address to the impact, and especially measure the distribution of the maximum bending moment generated on the shaft near the top of swing and when the cock is released. The characteristics including the condition of the shaft are determined from the curvature distribution obtained from the bending stiffness distribution, and a golf shaft is constituted by such a shaft, and a golf club having such a golf shaft is constituted.

The invention according to claims 7, 14 and 21 is as follows:
Measure the distribution of the bending moment applied to the shaft during the swing from the address to the impact, especially measure the distribution of the maximum bending moment in the toe-down direction that occurs on the shaft immediately before the impact, and use the data and the bending rigidity distribution of the shaft to measure A characteristic including the condition of the shaft is determined from the obtained curvature distribution, a golf shaft is configured using the determined shaft, and a golf club including such a golf shaft is configured.

[0018]

FIG. 1 is a view showing a shaft bending rigidity measuring device used in an embodiment of the present invention. In FIG. 1, a shaft bending stiffness measuring device 1 measures a bending curve y (x) and an outer diameter D (x) of a shaft 2 of a golf club, and the grip side of the shaft 2 is fixed by a fixing portion 11. In addition, a torque sensor 12 that can move in the y direction is provided on the tip end side of the shaft 2.
A jig 2a is mounted on the tip of the shaft 2. When the jig 2a is moved in the y direction in FIG. 1 to give a bending moment, the torque sensor 12
d is detected.

The shaft bending rigidity measuring device 1 is provided with a laser size measuring device 13. The laser dimension measuring device 13 includes a pair of gauges 14 and 15 facing each other so as to sandwich the shaft 2, is movable in the length direction of the shaft 2, and has a pair of gauges 14 and 15 and a distance between the pair of gauges 14 and 15. Is adjustable. The bending curve y (x) and the outer diameter D (x) of the shaft 2 are measured by sequentially moving the laser size measuring device 13 from the fixed portion 11 side to the tip portion side of the shaft 2 as indicated by 13a and 13b.

FIG. 2 is a schematic block diagram of an embodiment of the present invention. 2, the load Load and the deflection y measured by the shaft bending rigidity measuring device 1 shown in FIG.
The data of (x) and the outer diameter D (x) are given to the CPU 4. The input unit 3 and the output unit 5 are connected to the CPU 4. The input unit 3 is composed of, for example, a keyboard or the like, and inputs necessary data. The CPU 4 processes a program based on a flowchart shown in FIG. 3 described later, and outputs the result to the output unit 5. As the output unit 5, for example, a printer or a display is used.

FIG. 3 is a flowchart showing an operation of measuring the bending stiffness distribution of the golf club shaft according to one embodiment of the present invention.

Next, referring to FIGS.
A method of obtaining the bending rigidity EI in the length direction will be described. As shown in FIG. 1, the grip side of the shaft 2 is fixed by the fixing portion 11, a bending moment is applied to the tip of the shaft 2 by the torque sensor 12, and the laser dimension measuring device 13 is moved from the fixing portion 11 side of the shaft 2 to the tip. Move to the side to measure the deflection curve y (x) and the outer diameter D (x)
Input to PU4. The CPU 4 has a torque sensor 1
2, the load Load is also input.

In general, when a bending moment M (x) acts on a beam (here, a shaft), when a radius of curvature of a neutral surface in a cross section of the beam is R (x), an x-axis extends in a longitudinal direction of the shaft 2. And the bending rigidity EI (x) is obtained as follows. That is, the CPU 4 calculates the deflection curve y (x) of the shaft neutral shaft based on the input data by the following equation.

Y (x); (x, y) Next, the CPU 4 approximates the circle by the least squares method and calculates the radius R
And the center (a, b) are calculated by the following equation.

(X−a) ² + (y−b) ² = R ^{2 Then} , the curvature distribution 1 / R (x) is calculated by the following equation.

1 / R (x) =-｛d ² y (x) / d
x ² ｝ / ｛1+ (dy (x) / dx) ² ｝ ^{3/2 Further} , the CPU 4 calculates and complements the bending moment M (x) from the load amount Load and the distance x from the load.

M (x) = Load × x Then, the CPU 4 calculates the bending stiffness distribution EI of the shaft 2.
(X) is calculated by the following equation.

EI (x) = M (x) / {1 / R (x)} FIG. 4 shows the measurement results of the bending rigidity EI and the outer diameter D in the longitudinal direction of the shaft measured in one embodiment of the present invention. It is a figure showing an example. Regarding the measurement accuracy of the result measured in this embodiment, when measuring an iron round bar with a known bending rigidity,
Good agreement was found. Table 1 is a table showing the results of the measurement accuracy in the embodiment shown in FIG. As is clear from Table 1, it is clear that the difference between the measured value and the calculated value of the bending stiffness is small.

[0029]

[Table 1]

Further, a bending moment M (x) acting on a minute portion of the straight beam is obtained from the relationship of the bending of the straight beam.

M (x) = EI (x) · {d ² y (x) / dx ² } By solving the differential equation for x from the above equation and obtaining the bending y of the shaft, y (x) = {M (x) / EI (x)} dx · dx +
C1 · x + C2 C1, C2: integration constant A static analysis result of a bending amount y (x) of a cantilever bending test under a static load of the shaft using the equation and data of a bending rigidity distribution measured by a shaft bending rigidity measuring device,
Good agreement was also found in the comparison of the measurement results of the amount of deflection in the cantilever deflection test under a static actual load. Table 2 shows the results of the measurement accuracy of the measuring device according to the embodiment of the present invention.

[0032]

[Table 2]

As described above, by establishing a shaft bending rigidity measuring device with high measurement accuracy, it is possible to measure the distribution of the bending moment applied to the shaft during the swing as described below.

FIG. 5 is a diagram showing an apparatus for measuring a distortion generated on a shaft during a swing from an address to an impact. As shown in FIG. 5 (a), the shaft 2 of FIG.
As shown in the cross-sectional view, strain gauges 61 and 62 are provided in the x-axis direction and the y-axis direction. These strain gauges 6 have x
The amount of distortion in the directions y and y is detected. The detected output of the strain gauge 6 is input to the amplifier 8 via the bridge box 7 and amplified as shown in FIG. 5C, the distortion waveform is analyzed by the FFT analyzer 9, and the distortion waveform is input to the personal computer 10. You.

FIG. 6 shows data measured by the apparatus shown in FIG. 5, data of the shaft outer diameter, bending rigidity distribution, the position of the strain gauge attached to the measurement graph, and the assembling conditions of the club head and the shaft. FIG. 8 is a diagram showing a flowchart for measuring a distribution of a bending moment applied to a shaft during a swing from an address to an impact according to various measurement conditions such as measurement.

In order to analyze the distribution of the bending moment applied to the shaft during the swing of a typical golfer by processing the program based on the flowchart shown in FIG. 6, various types of golfers, including professional golfers, from women to men. 29 subjects (experts to amateurs; 20 men [: A01 to A20], 9 women [: B01 to B09]) performed 5 swings per club, and each club performed 1 to 3 clubs. A hit was performed.

Table 3 shows the specification values of the club and shaft used in the experiment. The experimental clubs [: C1 to C9] were wood clubs using a driver (1 W). Then, the bending strain is measured for each club by the apparatus shown in FIG.
Here, the tensile / compressive strain was ignored because it was smaller than the bending strain.

[0038]

[Table 3]

FIG. 7 is a diagram showing the distribution of the bending moment M (x, t) applied to the shaft in the x and y directions during the swing measured by the apparatus shown in FIG. 5, and FIG. 8 is a diagram showing the shaft just before impact. FIG. 9 is a diagram showing the distribution of the bending moment in the swing direction according to FIG.

FIG. 10 shows M in the x direction just before the impact.
It is a figure which shows the classification | category by the cluster classification method of a multivariate analysis using (x, t), and extracts the data of the distribution of the bending moment applied to the shaft during the swing of a typical golfer by this analysis. FIG. 11 is a view showing the outer diameter and bending rigidity distribution EI (x) of a typical pre-toned steel shaft and a hand-toned shaft, and FIG. 12 is a typical pre-toned steel shaft and a hand-toned steel shaft. FIG. 9 is a diagram showing a rate of change dK (x, t) / dt of the curvature distribution of the shaft immediately before impact of FIG.

As a second embodiment of the present invention, the distribution of the bending moment applied to the shaft during the swing from the address to the impact shown in FIG. 7 is measured.
As shown in FIG. 9, the distribution M (x, t) of the bending moment in the swing direction applied to the shaft immediately before the impact and the rate of change dM (x, t) / dt shown in FIG. 9 are measured. Next, the change rate dM (x, t) / dt and FIGS. 11 (a) and 11 (b)
12A and 12B, the rate of change dK of the curvature distribution obtained from the bending rigidity distribution EI (x) of the shaft shown in FIG.
The condition of the shaft is determined from (x, t) / dt. Then, the golf shaft and the golf club equipped with the shaft are realized by the shaft having the determined condition.

8 and 9, the data of M (x, t) immediately before the impact and the change rate dM (x,
In the data of t) / dt, it is almost intermediate data among 29 subjects, and it is predicted that most golfers are classified here. In the following description, an analysis result for an intermediate golfer is shown. In this classification, FIG.
As shown in FIG. 0, M (x,
Using t), classification is performed by a cluster analysis method of multivariate analysis; agglutination method [tree clustering method] (distance velocity: Euclidean distance: connection rule: group average method (UPGMA method) is used). An intermediate golfer (representative golfer) was extracted.

Next, as a third embodiment of the present invention, the distribution of the bending moment applied to the shaft during the swing is measured, and in particular, the distribution M (x, t) of the bending moment in the swing direction applied to the shaft immediately before impact is measured. ) And its rate of change dM (x, t) / dt are measured, and then its rate of change dM (x, t) / dt and the bending stiffness distribution E of the shaft.
Change rate of curvature distribution dK (x, t) obtained by I (x)
The condition of the shaft is determined from the ratio (area ratio) of each part of / dt. Then, a golf shaft and a golf club equipped with the shaft are realized by the shaft whose tone is determined.

FIG. 13 shows the rate of change dK (x, t) / of the curvature distribution immediately before impact of a typical pre-toned steel shaft having the bending rigidity distribution EI (x) shown in FIG.
FIG. 14 is a diagram showing the ratio of dt, and FIG. 14 shows the rate of change d in the curvature distribution immediately before impact of a typical hand-shaped steel shaft having the bending rigidity distribution EI (x) shown in FIG.
It is a figure which shows the ratio of K (x, t) / dt.

FIG. 13 (a) shows the rate of change dK of the curvature distribution of a typical pre-toned steel shaft immediately before impact.
(X, t) / dt shows the ratio (area ratio) of the shaft portion occupied by half of each of the head side and the grip side,
FIG. 14 (a) shows the ratio (area ratio) of the head portion and the grip side of the shaft portion at the rate of change dK (x, t) / dt of the curvature distribution immediately before the steel shaft of a typical hand tone, on the head side and the grip side, respectively. ). However, in each case, the neck portion of the head and the portion corresponding to the grip portion are excluded.

Next, a fourth embodiment will be described.
In the fourth embodiment, the distribution of the bending moment applied to the shaft during the swing is measured. In particular, the distribution M of the moment in the swing direction applied to the shaft immediately before impact is measured.
(X, t) and its rate of change dM (x, t) / dt are measured. Next, at the rate of change dM (x, t) / dt and the rate of change dK (x, t) / dt of the curvature distribution determined by the bending stiffness distribution EI (x) of the shaft, the club head neck portion and the grip portion have the following characteristics. The condition of the shaft is determined from the ratio (area ratio) of each of the three equally divided portions in the shaft portion excluding the corresponding portion. Then, a golf shaft having the determined condition and a golf club equipped with the shaft are realized.

As an example of the fourth embodiment, FIG.
As shown in FIG. 3 (b), a change rate dK (x, t) / dt of the curvature distribution immediately before the impact of a typical pre-toned steel shaft occupies one third of the head side, middle part and grip side of the shaft part. The ratio (area ratio) is shown in FIG. 14 (b), and the change rate dK (x, t) / dt of the curvature distribution immediately before the impact of the typical hand-held steel shaft, the head side, the middle part, and the grip of the shaft part The ratio (area ratio) occupied by one third of each side is shown. However, in each case, a portion corresponding to a head neck portion and a grip portion is excluded.

Here, the ratio of the change rate dK (x, t) / dt of the curvature distribution on the head side to the change rate dK (x, t) / dt of the curvature distribution of the entire shaft is newly referred to as “dynamic flexible The ratio, which is called "Dynamic Flexible Ratio", is divided into three equal parts, the head side, the center part, and the grip side of the shaft.
Ratio middle "and" DF Ratio butt ".

Next, a fifth embodiment will be described.
In the fifth embodiment, the distribution of the bending moment applied to the shaft during the swing is measured. In particular, the distribution M (x, t) of the bending moment in the swing direction applied to the shaft immediately before impact and the change rate dM (x, t) / dt is measured. Next, the condition of the shaft is determined from the position of the peak of the rate of change dK (x, t) / dt of the curvature distribution obtained from the rate of change dM (x, t) / dt and the bending rigidity distribution EI (x) of the shaft. Is done. Then, a golf shaft and a golf club equipped with the shaft are realized using the shaft whose tone is determined.

According to the fifth embodiment, the aforementioned FIG.
According to (a) and FIG. 12 (b), the position of the peak of the rate of change dK (x, t) / dt of the curvature distribution immediately before the impact of the representative pre-toned and hand-toned steel shafts is It can be confirmed that the peak exists at 400 to 500 mm, and the hand tone shaft has a slight peak around 700 to 800 mm.

The rate of change dK (x,
Since t) / dt indicates the speed of change (rate of change) of the bending of the shaft during the swing, the maximum point of this distribution in this embodiment is the largest before the impact, and The position of this peak will be referred to as a “dynamic kick point”.

Next, a sixth embodiment will be described.
In the sixth embodiment, the distribution of the bending moment applied to the shaft during the swing is measured, and in particular, the distribution of the maximum bending moment generated on the shaft near the top of swing or when the cock is released is measured. Next, the characteristics of the shaft are determined from the data of the bending moment distribution and the curvature distribution obtained from the bending rigidity distribution of the shaft. Then, a golf shaft and a golf club equipped with the shaft are realized using the shaft whose characteristics are determined.

FIG. 15 shows the distribution of the maximum bending moment generated on the shaft near the top of swing and near the cock release according to the sixth embodiment described above, and FIG. 16 shows the distribution near the top of swing and near the cock release when the cock is released. 3 shows a curvature distribution of a shaft.

Next, a seventh embodiment will be described.
In the seventh embodiment, the distribution of the bending moment applied to the shaft during the swing is measured, and the distribution of the maximum bending moment in the toe-down direction generated on the shaft immediately before impact is measured. Next, the characteristics of the shaft are determined based on the bending moment distribution data and the curvature distribution obtained from the bending rigidity distribution of the shaft. Then, a golf shaft and a golf club equipped with the shaft are realized using the shaft whose characteristics have been determined.

FIG. 17 shows the distribution of the maximum bending moment in the toe-down direction generated on the shaft immediately before impact, and FIG. 18 shows the curvature distribution of the shaft in the toe-down direction generated on the shaft immediately before impact.

Next, an eighth embodiment will be described.
In the eighth embodiment, the distribution of the bending moment applied to the shaft during the swing is measured. Next, the data of the bending moment during the swing and the rate of change thereof and the curvature distribution and the rate of change obtained from the bending rigidity distribution of the shaft are used to determine the shaft. Is determined. Then, a golf club is realized by using the shaft whose characteristics have been determined and by mounting the golf shaft and the shaft.

According to the above-described embodiment, it is possible to match the performance including the tone measured by the shaft itself with the sensation that the golfer feels or evaluates as a feeling during a swing.

FIG. 19 shows the ratio of the rate of change dK (x, t) / dt of the curvature distribution on the head side to the rate of change dK (x, t) / dt of the curvature distribution of the entire shaft. 1 and the “tilt angle of the shaft tip” immediately before the impact. The larger the ratio, the larger the "tilt angle of the shaft tip", and the tendency became almost linear.

FIG. 20 is a diagram showing "DF Ratio tip" and "the tilt angle of the shaft tip" immediately before impact. In the same manner as in FIG. 19 described above, the larger the ratio, the larger the “tilt angle of the shaft tip”, and the tendency becomes almost linear. In particular, when the rate of change dK (x, t) / dt of the curvature distribution of the head side third is taken, as a result of the first-order approximation by the least squares method, the correlation coefficient is 0.88 (y = 0 0.0688 · x + 1.3144: n =
21; Flex S), showing the maximum.

From the above, it has been clarified that the magnitude of the “DF Ratio tip” is indispensable for the “tone” judgment and is greatly related to the launch angle of the hit ball. In addition, "DF Ratio
No correlation was found between any of the parameters for "middle" and "DF Ratio butt", but it is presumed that they affect the golfer's feeling and how to take the timing of the swing.

FIG. 21 shows “DF Ratio tip” and “DF Ratio b”.
It is a figure which shows the relationship of "utt" / "DF Ratio middle".
In FIG. 21, “DF Ratio tip” on the horizontal axis indicates the rate of change dK (x,
At a rate of t) / dt, there is a correlation with the launch angle of the hit ball (the tilt angle of the shaft tip). On the other hand, the vertical axis "DF Rat
"io butt" / "DF Ratio middle" is the rate of change dK in the curvature distribution of the shaft grip with respect to the shaft middle.
This is a ratio of the ratio of (x, t) / dt. When this value is large, it indicates that the rate of change of the bending of the grip portion is larger than that of the middle portion of the shaft.

In FIG. 21, ● (n = 17) shows data of a typical steel shaft used since the 1960's. These steel shafts are "pre-toned",
It is universally divided into "medium tone" and "hand tone"
When the “tone” is determined based on the data, the DF Ratio
It can be seen that “first tone” and “hand tone, medium tone” are classified with a tip of 20%. Also, DF Ratio b
utt / DF Ratio middle $ 1.2

The circles (n = 71) in FIG. 21 indicate the distribution of CFRP shafts currently on the market. It can be seen that the dispersion state of the CFRP shaft is considerably discrete with respect to the dispersion state of the steel shaft, and it is clear that the degree of design freedom is large. Also, as can be seen from the histogram for each axis, the above-mentioned boundary value “DF Ratio tip ≒
20 (%) "and" DF Ratio butt / DF Ratio middl
It can be confirmed that “e ≒ 1.2” is almost an intermediate value of each histogram. Therefore, in the same manner as described above,
"Tone" classification is possible. In addition, it can be inferred that in the era of the heyday of the steel shaft and the heyday of the CFRP shaft, the standards such as the concept and the design have not changed much.

FIG. 22 is a diagram showing an example of the relationship between "dynamic kick point" and "shaft tip inclination angle".
In FIG. 22, the “dynamic kick point” tends to increase the inclination angle of the tip of the shaft near the head, but no significant correlation was obtained.

FIG. 23 shows the first to fifth embodiments described above.
It is a figure showing a 7th embodiment by a flow chart.

[0066]

As described above, according to the present invention, the distribution of the bending moment applied to the shaft during the swing is measured, and the bending moment during the swing at a specific time (for example, before the impact, near the top of the swing, etc.) is measured. Golf club and a golf club equipped with the shaft, the performance including the condition of the shaft can be determined from the curvature distribution and the rate of change obtained from the data of the rate of change of the shaft and the distribution of the bending rigidity of the shaft. In the above, the performance including the tone measured by the shaft itself can be matched with the sensation that the golfer feels or evaluates as a feeling during the swing.

[Brief description of the drawings]

FIG. 1 is a view showing a shaft bending rigidity measuring device used in an embodiment of the present invention.

FIG. 2 is a schematic block diagram of an embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of determining the condition of the golf club shaft according to the embodiment of the present invention.

FIG. 4 is a diagram showing an example of a measurement result of a bending rigidity EI and an outer diameter D in a longitudinal direction of a shaft measured in an embodiment of the present invention.

FIG. 5 is a diagram showing an experimental device for measuring a distribution of a bending moment applied to a shaft during a swing from an address to an impact.

FIG. 6 is a diagram for measuring and analyzing a distribution of a bending moment applied to a shaft during a swing from an address to an impact, based on data measured by the apparatus of FIG. 5, data on a shaft outer diameter and bending stiffness distribution, and various measurement conditions. It is a flowchart.

7 is a diagram showing a distribution of a bending moment M (x, t) applied to a swing shaft measured by the device shown in FIG.

FIG. 8 is a diagram showing a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact.

FIG. 9 is a diagram showing a rate of change of a bending moment in a swing direction applied to a shaft immediately before an impact.

FIG. 10: Bending moment M in x direction just before impact
It is a figure showing classification by a cluster classification method of multivariate analysis using (x, t).

FIG. 11 is a diagram showing the outer diameter and bending rigidity distribution EI (x) of (a) a typical pre-toned steel shaft and (b) a hand-toned shaft.

FIG. 12 is a diagram showing a change rate dK (x, t) / dt of a curvature distribution immediately before impact of (a) a typical pre-toned steel shaft and (b) a hand-toned steel shaft.

FIG. 13 shows a ratio of a change ratio dK (x, t) / dt of a curvature distribution of a typical pre-toned steel shaft having a bending rigidity distribution EI (x) shown in FIG. FIG.

FIG. 14 shows the rate of change dK (x, t) of the curvature distribution immediately before impact of a typical hand-held steel shaft having the bending rigidity distribution EI (x) of the shaft shown in FIG. 11 (b).
It is a figure which shows the ratio which each part of / dt occupies.

FIG. 15 is a diagram showing a distribution of a maximum bending moment generated in a shaft near a top swing or when a cock is released.

FIG. 16 is a diagram showing a curvature distribution of a shaft near a top of swing or when a cock is released.

FIG. 17 is a diagram showing the distribution of the maximum bending moment in the toe-down direction generated on the shaft immediately before impact.

FIG. 18 is a diagram showing a curvature distribution of the shaft in the toe-down direction generated on the shaft immediately before impact.

FIG. 19 shows a rate of change dK (x,
FIG. 9 is a diagram showing the ratio of dK (x, t) / dt on the head side to t) / dt.

FIG. 20 is a diagram showing a “DF Ratio tip” and a “tilt angle of a shaft tip” immediately before impact.

[Figure 21] “DF Ratio tip” and “DF Ratio butt” /
It is a figure which shows the relationship of "DF Ratio middle."

FIG. 22 is a diagram illustrating an example of a relationship between a “dynamic kick point” and a “tilt angle of a shaft tip”;

FIG. 23 is a flowchart showing the operation of the first to seventh embodiments.

FIG. 24 is a view showing the structure of a conventional CFPR golf shaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft bending rigidity measuring device 2 Shaft 3 Input part 4 CPU 5 Output part 11 Fixed part 12 Torque sensor 13 Laser dimension measuring instrument 14, 15 gauge 6, 61, 62 Strain gauge 7 Bridge box 8 Amplifier 9 FFT analyzer 10 Personal computer

Claims (21)

[Claims] 1. A method for determining the condition of a golf club shaft during a swing from an address to an impact, comprising measuring a distribution of a bending moment applied to the shaft during the swing, and measuring the measured data and the data of the shaft. A method for determining a characteristic including a condition of a shaft from a curvature distribution obtained from a bending rigidity distribution. 2. A method for determining a condition of a golf club shaft during a swing from an address to an impact, wherein a distribution of a bending moment applied to the shaft during the swing is measured, and in particular, a swing applied to the shaft immediately before the impact is measured. Measuring a rate of change of the distribution of the bending moment in the direction, and determining a characteristic including a condition of the shaft from the measured data and a rate of change of the curvature distribution obtained from the bending rigidity distribution of the shaft. 3. A method for determining a condition of a golf club shaft during a swing from an address to an impact, wherein a distribution of a bending moment applied to the shaft during the swing is measured, and in particular, a swing applied to the shaft immediately before the impact is measured. The rate of change of the distribution of the bending moment in the direction is measured, and the characteristic including the condition of the shaft is determined from the measured data and the ratio (area ratio) of each part of the rate of change of the curvature distribution obtained from the bending rigidity distribution of the shaft. A method comprising: 4. A method for determining a condition of a golf club shaft during a swing from an address to an impact, wherein a distribution of a bending moment applied to the shaft during the swing is measured, and in particular, a swing applied to the shaft immediately before the impact is measured. The rate of change of the distribution of the bending moment in the direction is measured, and the measured data and the rate of change of the curvature distribution obtained from the bending rigidity distribution of the shaft exclude the portion corresponding to the neck portion and the grip portion of the club head. And determining a characteristic including a condition of the shaft from a ratio (area ratio) of each of the three parts in the part. 5. A method for determining a condition of a golf club shaft during a swing from an address to an impact, wherein a distribution of a bending moment applied to the shaft during the swing is measured, and in particular, a swing applied to the shaft immediately before the impact is measured. Measuring the rate of change of the distribution of the bending moment in the direction, and determining characteristics including the condition of the shaft from the position of the peak of the rate of change of the curvature distribution obtained by the measured data and the bending rigidity distribution of the shaft. how to. 6. A method for determining a condition of a golf club shaft during a swing from an address to an impact, wherein a distribution of a bending moment applied to the shaft during the swing is measured, and particularly, a vicinity of a top of swing or a cock release. A method of measuring a distribution of a maximum bending moment generated in a shaft near the time, and determining a characteristic including a condition of the shaft from the measured data and a curvature distribution obtained from a bending rigidity distribution of the shaft. 7. A method for determining a condition of a golf club shaft during a swing from an address to an impact, wherein a distribution of a bending moment applied to the shaft during the swing is measured, and the distribution is particularly generated on the shaft immediately before the impact. A method of measuring a distribution of a maximum bending moment in a toe-down direction, and determining a characteristic including a condition of a shaft from the measured data and a curvature distribution obtained from a bending rigidity distribution of the shaft. 8. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured, and a characteristic including a condition of the shaft is determined by the data and a curvature distribution obtained from a bending rigidity distribution of the shaft. A golf shaft, characterized by being made. 9. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured, and in particular, a change rate of a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact is measured. A golf shaft, wherein characteristics including a condition of the shaft are determined based on a change rate of a curvature distribution obtained from data and a bending rigidity distribution of the shaft. 10. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured, and particularly, a change rate of a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact is measured. A golf shaft, wherein characteristics including a condition of the shaft are determined by a ratio (area ratio) of each portion of a rate of change of a curvature distribution obtained from data and a bending rigidity distribution of the shaft. 11. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured, and particularly, a change rate of a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact is measured. In terms of the rate of change of the curvature distribution obtained from the data and the bending rigidity distribution of the shaft, the condition of the shaft is determined by the ratio (area ratio) of each of the three equally divided portions of the shaft portion excluding the portion corresponding to the neck portion and the grip portion of the club head. A golf shaft characterized in that characteristics including: are determined. 12. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured. In particular, a rate of change of a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact is measured. A golf club shaft, wherein characteristics including a condition of the shaft are determined from a peak position of a rate of change of a curvature distribution obtained from data and a bending rigidity distribution of the shaft. 13. A distribution of a bending moment applied to a shaft during a swing from an address to an impact is measured. In particular, a distribution of a maximum bending moment generated in a shaft near a top-of-swing or when a cock is released is measured. A golf shaft, wherein characteristics including a condition of a shaft are determined by a curvature distribution obtained from data and a bending rigidity distribution of the shaft. 14. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured. In particular, a distribution of a maximum bending moment in a toe-down direction generated on the shaft immediately before the impact is measured. A golf shaft, wherein characteristics including a condition of a shaft are determined by a curvature distribution obtained from data and a bending rigidity distribution of the shaft. 15. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured, and characteristics including a condition of the shaft are determined from the data and a curvature distribution obtained from a bending rigidity distribution of the shaft. A golf club comprising a shaft. 16. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured, and in particular, a rate of change of a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact is measured. A golf club characterized in that the characteristics including the condition of the shaft are determined from the change rate of the curvature distribution obtained from the data and the bending rigidity distribution of the shaft, and such a shaft is mounted. 17. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured, and particularly, a change rate of a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact is measured. A golf club characterized in that the characteristics including the condition of the shaft are determined from the ratio (area ratio) of each part of the rate of change of the curvature distribution obtained from the data and the bending rigidity distribution of the shaft, and such a shaft is mounted. 18. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured. In particular, a rate of change of a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact is measured. In the rate of change of the curvature distribution obtained from the data and the bending rigidity distribution of the shaft, the condition of the shaft is calculated from the ratio (area ratio) of each of the three portions of the shaft portion excluding the portion corresponding to the neck portion and the grip portion of the club head. A golf club characterized in that characteristics including the following are determined, and such a shaft is mounted. 19. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured, and in particular, a rate of change of a distribution of a bending moment in a swing direction applied to a shaft immediately before an impact is measured. A golf club comprising: a characteristic including a condition of a shaft determined by a peak position of a rate of change of a curvature distribution obtained from data and a bending stiffness distribution of the shaft. 20. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact, and particularly, a distribution of a maximum bending moment generated on the shaft near a top of swing or when a cock is released. A golf club characterized in that characteristics including the condition of the shaft are determined based on the data and the curvature distribution obtained from the bending rigidity distribution of the shaft, and such a shaft is mounted. 21. A distribution of a bending moment applied to a shaft of a golf club during a swing from an address to an impact is measured. In particular, a distribution of a maximum bending moment in a toe-down direction generated on the shaft immediately before the impact is measured. The characteristic including the condition of the shaft is determined from the curvature distribution obtained from the data and the bending rigidity distribution of the shaft, and the characteristic that the shaft is mounted is characterized in that:
Golf club.