JP2003205053A - Golf club shaft evaluation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To objectively determine a shaft optimal to a golfer by evaluating the dynamic behavior of a shaft including the torsional behavior of a golf club. <P>SOLUTION: Torsional strain generated at the shaft during swinging the golf club is measured to evaluate the dynamic behavior of the shaft including the torsional behavior of the shaft by data histeresis of the measured torsional strain. In particular, it is desirable to measure the torsional strain generated on the tip side of the shaft and to evaluate the dynamic behavior of the shaft by waveform data D1 to D4 of the torsional strain before impact. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club shaft evaluation system, and more particularly, to accurately evaluate dynamic behavior of a shaft including torsional behavior of the shaft when the golf club actually swings.

[0002]

2. Description of the Related Art Conventionally, in golf club shafts,
It is important to evaluate the shaft behavior such as the bending and twisting of the shaft which affects the performance such as the flight distance and the hitting direction. For example, in the static state of the shaft, the relative rigidity values of the front end side (head side) and the rear end side (grip side) of the shaft are measured, and if the front end is less rigid than the rear end, On the contrary, the shaft is evaluated as the tone at hand if the front end has higher rigidity than the rear end.
Further, not only the rigidity at two points on the front end side and the rear end side of the shaft, but also the rigidity is finely investigated from the front end to the rear end, and the shaft is evaluated by the rigidity distribution of the entire shaft in a static state. .

Although the behavior of the static shaft has been quantitatively evaluated as described above, in such a static state, a force is actually applied to the golf club shaft during the swing of the golf player. Since it is different from the dynamic state, the static evaluation is insufficient as the evaluation corresponding to the actual swing.

At present, a golfer's sensual evaluation is generally used as a dynamic evaluation of a golf club shaft.
However, even with the same shaft, the feeling changes depending on the day, and there are some golfers who can not feel bending or twisting, so only sensory evaluation makes bending and twisting etc. The evaluation of the dynamic behavior of the shaft is poor. Therefore, it is desired to establish an evaluation method capable of quantitatively evaluating the dynamic behavior of the shaft, and various proposals have been made.

For example, Japanese Patent Laid-Open No. 2001-190711 proposes an iron club set in which the suitability of the club set is evaluated from the bending strain amount in the swing direction and the toe down direction during the swing. In addition, JP-A-1
No. 1-178953 proposes a shaft bending behavior analysis system that analyzes the bending behavior of a shaft from static bending rigidity and bending strain during a swing. Further, Japanese Patent Laid-Open No. 2000-79186 proposes a golf club shaft in which swings are classified into four types, and the optimum club for a golfer can be quantitatively grasped from bending strains and torsional strains during swings.

[0006]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
In Japanese Patent Laid-Open No. 001-190711 and Japanese Patent Laid-Open No. 11-187953, the dynamic behavior of the shaft is evaluated by using the shaft strain obtained from the actual golf swing, but it is obtained by measuring the bending strain. Since the evaluation is made only from the bending in the shaft axis direction, there is a problem that the behavior in the twisting direction around the shaft axis cannot be evaluated.

Further, in Japanese Patent Laid-Open No. 2000-79186,
Since the torque of the shaft is only detected using the torsional strain, the dynamic torsional behavior cannot be grasped, and the dynamic behavior in the torsional direction of the shaft has not been evaluated. Not enough to grasp the swing.

As described above, when the golf club shaft is evaluated, it is conventionally conducted by investigating the bending (bending strain) in the shaft axial direction. Regarding the shaft design, based on the evaluation of bending rigidity, advanced users are provided with a shaft having high bending rigidity and high torsional rigidity, and beginners are provided with a shaft having low bending rigidity and torsional rigidity. Therefore, the behavior of the shaft in the twisting direction is not considered,
Actually, there is a problem that the optimum shaft cannot be selected for each golfer.

The present invention has been made in view of the above-mentioned problems, and it is possible to evaluate the dynamic behavior of the shaft including the twisting behavior of the golf club, and to objectively determine the optimum shaft for the golfer. The challenge is to provide a shaft evaluation system.

[0010]

In order to solve the above problems, the present invention measures the torsional strain generated on a shaft during the swing of a golf club, and based on the time history data of the measured torsional strain, the torsional behavior of the shaft is determined. A golf club shaft evaluation system characterized by evaluating the dynamic behavior of a shaft including the golf club shaft.

As described above, since the golf club shaft evaluation system of the present invention evaluates using the time history data of the torsional strain generated in the shaft during the actual swing, the torsion of the shaft at each time during the swing is evaluated. The condition can be grasped, and the dynamic behavior of the shaft including the torsional behavior of the shaft can be evaluated accurately. Further, even for a golfer such as a golf beginner who does not feel the twist of the shaft, it is possible to objectively determine the optimum golf club shaft for each golfer by using the quantitative index.

Specifically, the larger the value of the torsional strain measured at an arbitrary position on the shaft, the larger the torsional amount of the shaft, and the torsional amount can be evaluated by the magnitude of the strain value. The torsional direction of the shaft can be evaluated depending on whether the measured torsional strain is a positive value or a negative value. When the ball is actually hit during the swing, it is possible to perform an accurate evaluation by combining the hitting direction and the flight distance with the time history data of the torsional strain.

Further, it is preferable that at least the torsional strain occurring on the tip side of the shaft is measured to evaluate the dynamic behavior of the shaft. The tip side of the shaft on which the head is mounted has a small shaft diameter, low torsional rigidity, and is easily twisted. Further, since it is close to the head that impacts the ball, it has a great influence on the ball striking direction. Therefore, by performing an evaluation based on the data of the torsional strain on the tip side, it becomes easier to understand the influence of the torsion of the shaft on the hit ball, and the evaluation accuracy can be improved. Furthermore, in order to efficiently evaluate the torsional behavior of the entire shaft, it is preferable to measure the torsional strain generated at both end sides of the shaft on the tip side and the rear end side. It is preferable to measure the torsional strain generated at the intermediate position of the shaft.

The measurement accuracy increases as the number of torsional strain measurement points increases, but if the number is too large, the original swing behavior of the shaft may be affected, and evaluation time may be required. For this reason, it is preferable that the number of wood-type clubs is 4 to 8 and the number of iron-type clubs is 3 to 5. Moreover, it is preferable to measure on a straight line in the axial direction from the front end to the rear end of the shaft. Note that the measurement may be performed at any position in the circumferential direction of the shaft.

It is preferable to evaluate the dynamic behavior of the shaft by using the maximum amplitude before impact or / and the strain value immediately before impact in the waveform of the time history data of the torsional strain. In particular, by observing the shaft behavior before the impact, it is possible to judge whether the golfer can swing efficiently or whether the shaft fits the swing form of the person. Specifically, the amount of torsion of the shaft at an arbitrary position of the shaft before the impact can be evaluated by the maximum amplitude before the impact. Further, the twist value of the shaft at an arbitrary position on the shaft immediately before the ball is actually impacted can be evaluated from the strain value immediately before the impact.

The bending strain in the axial direction of the shaft is measured, and the time history data of the bending strain and the time history data of the torsion strain are combined to evaluate the dynamic behavior of the shaft in both bending behavior and torsion behavior. You can also do

The above-mentioned torsional strain may be measured by attaching a strain gauge to the shaft and wired through a cable, or may be measured by transmitting wirelessly the data of the torsional strain detected on the shaft. Strain measurement is preferably performed with a strain gauge because it provides appropriate accuracy, is easy to install, and is inexpensive. In addition, because the strain gauge is extremely lightweight and small, it does not feel uncomfortable for the golfer when swinging, there is little signal noise from the outside, and the time from processing to processing the detected signal is low. Is possible in a short time. The gauge length is preferably about 1 to 5 mm.

In order to obtain data when the golf club swings, a golfer may actually swing the golf club, or a swing robot may swing to evaluate the shaft. The ball may be actually hit during the swing, or only the swing may be performed.

The material of the shaft evaluated by the evaluation system is not particularly limited, and various conventionally used materials such as fiber reinforced resin and metal can be used. It can be applied to all types of golf clubs such as drivers, irons and putters.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a golf club shaft evaluation system of the present invention will be described below with reference to the drawings. 1A and 1B show a golf club 10 on which a golfer actually swings. Golf club 10
Includes a shaft 11 made of fiber reinforced resin having carbon fiber as a reinforcing fiber, a head 12 for a driver is attached to the tip of the shaft 11 on the small diameter side, and a grip 13 is attached to the end of the shaft 11 on the large diameter side. .

The shaft 11 has four strain gauges 2
1 to 24 are sequentially attached from the head side on the same plane (position of 90 degrees in the circumferential direction of the shaft with respect to the face 12b of the head 12) on the same axis line in the long axis direction of the shaft 11. It is configured to detect the twist in the direction around the axis of.

The strain gauge 21 is attached to the head 12 side (tip side), and the distance from the end 12a of the head 12 to the center of the detecting portion 21a of the strain gauge 21 is 2
It is set to 0 mm. The strain gauge 24 is attached to the grip 13 side, and the end portion 13 of the grip 13 is attached.
The distance from a to the center of the detection portion 24a of the strain gauge 24 is 20 mm. The strain gauges 22 and 23 are attached to intermediate positions in the axial direction of the shaft 11, and the detection portions 22a and 23a of the strain gauges 22 and 23 are located between the detection portion 21a of the strain gauge 21 and the detection portion 24a of the strain gauge 24. They are evenly arranged (at three equally divided positions). The strain gauges 21 to 24 are biaxial gauges for torsional strain.

As shown in FIG. 2, strain gauges 21 to 2
The cables 21b to 24b of No. 4 are attached to the grip side along the shaft 11, and further attached from the wrist of the golfer G to the arm, and the other ends of the strain gauges 21 to 24 are set to the dynamic strain gauge 25. Connected to.

The golf club G swings the golf club 10 to which the strain gauges 21 to 24 are attached as described above, the torsional strain generated on the shaft 11 during the swing is measured, and the time history data of the measured torsional strain is used.
The dynamic behavior of the shaft is evaluated, including the torsional behavior of the shaft.

Specifically, in FIG. 3, strain gauges 21-
The waveform data D1 to D4 of the time history data of the torsional strain measured at 24 are shown. Data from 0.55 seconds before impact to 0.05 seconds after impact are displayed.
The dynamic behavior of the shaft including the twisting behavior of the shaft 11 is evaluated from the waveform data D1 to D4.

The data D1 at the position closest to the head 12 side of the shaft 11 has a large amplitude on the negative side (maximum amplitude of about 400 με) between 0.15 seconds before impact and the impact, as shown in FIG. It can be seen that before the impact, the amount of twist on the head 12 side of the shaft 11 increases in the direction in which the face 12b of the head 12 closes. In addition, the grip 13 rather than the data D1
In the data D2 to D4 on the side, the maximum amplitude is about 100 με and all swing to the positive side from 0.15 seconds before the impact to the impact, and the face of the head 12 extends from the intermediate position of the shaft 11 to the grip 13 side. 1
It can be seen that 2b is twisted in the opening direction.

Waveform D at each position on the shaft 11 of FIG.
Comprehensively judging from 1 to D4, although the face 12b is largely twisted in the closing direction on the tip end side of the shaft 11, the face 12b is twisted in the opening direction on the grip 13 side from the intermediate position of the shaft 11, so that the shaft 12b is twisted. 11 Twist offset as a whole, face 1
It can be determined that 2b is not so twisted.
From this result, it can be determined that the shaft 11 is suitable for the golf player G to some extent.

As described above, the twisting condition of the shaft 11 before the impact during the swing can be grasped by the waveform data D1 to D4 of the time history data of the torsional strain, and the dynamic state of the shaft including the twisting behavior of the shaft 11 can be grasped. The behavior can be evaluated accurately. Therefore, the optimum shaft for each golfer can be objectively determined.

Examples of the golf club shaft evaluation system of the present invention will be described in detail below. One golfer swings each golf club provided with two shafts (shafts A and B) having different structures as shown below, and hits the golf ball. Four strain gauges were attached to the two shafts A and B at the same positions as in the first embodiment, respectively.

Shaft A: Torque 5.5 degrees Shaft B: Torque 3.5 degrees The head used had a loft angle of 10 degrees. The tone was at hand, and the shaft weight was 55 g. Other conditions such as bending rigidity were the same.

Torsional strain generated at each position on the shaft during the swing of the golf club was measured with a strain gauge, and waveform data of time history data of the measured torsional strain was obtained. The shaft A is the same shaft as the shaft of the first embodiment, and the obtained waveform data D1 to D4 was the same as that of FIG. 3 described above. Waveform data D1 ′ to D4 ′ (D1 ′, D2 ′, D3 ′, D4 ′ in order from the head side) obtained from the swing of the shaft B are shown in FIG. The dynamic behavior of the shaft including the twisting behavior of each shaft was evaluated from these two types of waveform data, and combined with the hitting result, the quality of the shaft was judged for the tester. Table 1 below shows the maximum amplitude before the impact of the torsional strain generated during the swing of each shaft obtained from the waveform data, and the value of the strain immediately before the impact. In addition, the hitting results such as head speed are shown in Table 2 below.

[0032]

[Table 1]

[0033]

[Table 2]

As shown in the first embodiment, the shaft A has waveforms D1 to D at various positions on the shaft shown in FIG.
Comprehensively judging from 4, although the face is twisted largely in the closing direction on the tip side of the shaft, the face is twisted in the opening direction on the grip side from the intermediate position of the shaft, so the twist is canceled out for the entire shaft. , It was judged that the face was not twisted so much.

As shown in FIG. 5, the shaft B has strain data D1 'and D2' at positions close to the head side of the shaft.
Between 0.10 seconds before impact and the maximum amplitude is about 180 με, both of which swing to the positive side, and the head side of the shaft is twisted in the direction in which the head face opens before impact. all right. Further, the data D3 ′ and D4 ′ on the grip side have a maximum amplitude of about 100 με and sway to the positive side between 0.10 seconds before impact and the impact.
It was also found that the grip side of the shaft was also twisted in the direction in which the head face opened. For this reason, it was determined that the face of the shaft as a whole was opened, and the head did not return at the time of impact, resulting in poor hitting.

Further, as shown in Table 2, the results of hitting the ball show that the shaft A has a higher head speed and ball speed than the shaft B, and actually has a good hitting point. It was confirmed that there is. Also, the ball launch angle was close to the ideal value of 13 °, and it was confirmed that a good flight distance could be obtained. Further, it was found from the waveform data and the hitting result that it was better for this tester to increase the torsional rigidity of the shaft tip of the shaft A in order to obtain a better shaft. It was also found that a good shaft can be obtained even if the torsional rigidity of the shaft B is lowered.

[0037]

As is apparent from the above description, according to the present invention, it is possible to grasp the twisting condition of the shaft at any position on the shaft at each time during the swing, and the twisting behavior of the shaft is included. The dynamic behavior of the shaft can be accurately evaluated. Further, even for a golfer such as a golf beginner who does not feel the twist of the shaft, it is possible to objectively determine the optimum golf club shaft for each golfer by using the quantitative index. Further, it is possible to propose a design such as shaft rigidity for obtaining a better shaft.

Further, particularly by using the data of the torsional strain on the tip side of the shaft for the evaluation, the evaluation useful for the golfer can be carried out. Furthermore, the evaluation accuracy can be improved by performing the evaluation together with the actual hitting result.

[Brief description of drawings]

FIG. 1A is a schematic view of a golf club used in a first embodiment of the present invention, and FIG. 1B is a schematic plan view of the golf club.

FIG. 2 is a diagram showing a method for measuring a torsional strain generated on a shaft during a swing.

FIG. 3 is a diagram showing a waveform of time history data of torsional strain during swing of the shaft according to the first embodiment.

FIG. 4 is a diagram showing an opening / closing direction of a face of a head.

FIG. 5 is a diagram showing a waveform of time history data of torsional strain when the shaft B swings.

[Explanation of symbols]

11 shaft 12 heads 12b face 13 grip 21-24 strain gauge D1 to D4, D1 'to D4' waveform data

Claims (3)

[Claims] 1. A dynamic characteristic of the shaft including a torsional behavior of the shaft is evaluated by measuring a torsional strain generated on the shaft during a swing of the golf club and using time history data of the measured torsional strain. Golf club shaft evaluation system. 2. The golf club shaft evaluation system according to claim 1, wherein at least the torsional strain generated on the tip side of the shaft is measured to evaluate the dynamic behavior of the shaft. 3. The dynamic behavior of the shaft is evaluated by using the maximum amplitude before impact or / and the strain value immediately before impact in the waveform of the time history data of the torsional strain, in order to evaluate the dynamic behavior of the shaft. The golf club shaft evaluation system described.