JP2009172052A - Evaluation method of golf club shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaluation method of a golf club shaft, which enables the evaluation of a circumferential uniformity of the golf club shaft. <P>SOLUTION: The evaluation method of the golf club shaft includes: a step in which the golf club shaft is vibrated in the first direction orthogonal to its length to simultaneously measure the vibration in the first direction and the vibration in the second direction orthogonal to the first direction; a step in which the golf club shaft is rotated relatively at a prescribed circumferential angle with respect to the first direction on the center axis of the golf club shaft as the center of rotation to be vibrated in the first direction, so that the simultaneous measurement of the vibrations is repeated in the first and second directions; and a step in which the circumferential uniformity of the golf club shaft is evaluated using the set of the vibrations in the first and second directions measured at the respective positions where the golf club shaft is circumferentially rotated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a golf club shaft evaluation method for evaluating uniformity in the circumferential direction of a golf club shaft.

Currently, as golf club shafts, there are metal golf club shafts made of metal and FRP golf club shafts made of fiber reinforced composite material (FRP). Of the golf club shafts made of metal, in particular, those made of steel are called steel shafts. Among golf club shafts made of FRP, golf club shafts made of carbon fiber reinforced composite (CFRP) are called carbon shafts. It is.
Since a metal golf club shaft is isotropic, the metal constituting the shaft is unlikely to have different deformation characteristics in the circumferential direction of the shaft, which is felt sensibly when a golfer makes a test shot.

  On the other hand, a golf club shaft made of FRP is formed by, for example, winding a sheet-like FRP around a core metal rod. In a golf club shaft made of FRP, when FRP is wound around a metal rod at the time of formation, a portion where the FRP overlaps occurs, and a portion whose thickness is not uniform in the circumferential direction occurs. Also, FRP itself has anisotropy. From these facts, it is known that a golf club shaft made of FRP has different deformation characteristics in the circumferential direction of the shaft.

When a golfer makes a test hit, if the golf club shaft has different deformation characteristics in the circumferential direction of the shaft (when left and right shake occurs), the hit feeling and the directionality of the hit ball are affected.
However, there is no quantitative evaluation method for the difference in deformation characteristics in the circumferential direction of the golf club shaft (government of the left and right sides of the golf club shaft). For example, this golf club shaft is likely to be shaken, and the current situation is that the evaluation is limited to sensory evaluation.

  An object of the present invention is to provide a golf club shaft evaluation method capable of solving the problems based on the prior art and evaluating the uniformity of the golf club shaft in the circumferential direction.

  In order to achieve the above object, according to a first aspect of the present invention, a golf club shaft is vibrated in a first direction orthogonal to a longitudinal direction of the golf club shaft, A step of simultaneously measuring vibrations in a second direction orthogonal to the first direction; and the circumferential direction of the golf club shaft with respect to the first direction with the central axis of the golf club shaft as a rotation center , The golf club shaft is vibrated in the first direction, and the vibration in the first direction and the vibration in the second direction are measured simultaneously. Using the combination of the vibration in the first direction and the vibration in the second direction measured at each position where the golf club shaft is rotated in the circumferential direction. There is provided an evaluation method of a golf club shaft and a step of evaluating sex.

  In the second aspect of the present invention, one end of the golf club shaft is fixed, and the other end is vibrated in a first direction orthogonal to the longitudinal direction of the golf club shaft. A first step of simultaneously measuring a vibration of the shaft in the first direction and a vibration of the golf club shaft in a second direction orthogonal to the first direction and the longitudinal direction for a predetermined time; and The shaft is rotated at a predetermined angle in the circumferential direction and the center axis of the golf club as a rotation center, the one end is fixed, and the other end is vibrated in the first direction, and the golf A second step of repeatedly measuring the vibration of the club shaft in the first direction and the vibration of the golf club shaft in the second direction simultaneously for a predetermined time; and A third evaluation of circumferential uniformity of the golf club shaft is performed using a set of vibrations in the first direction and vibrations in the second direction measured at each position where the foot is rotated in the circumferential direction. And providing a method for evaluating a golf club shaft.

  In the present invention, the combination of the vibration in the first direction and the vibration in the second direction in the third step is a combination of the vibration obtained in the first step and the second step. The time-series data of vibration in the first direction and the time-series data of vibration in each second direction are divided into a plurality of blocks at predetermined time intervals, respectively, and time-series data of vibration in each first direction Calculating the square root of the sum of squares of the vibration in the first direction for each block of the first direction to obtain the average amplitude in the first direction, and for each block of the time-series data of the vibration in the second direction. The first direction measured at each position where the golf club shaft is rotated in the circumferential direction by calculating the square root of the square sum of the vibrations in the second direction to obtain an average amplitude in the second direction. The first of each block of time series data of vibration The average amplitude of, it is preferable the average amplitude of the second direction of each block of the time series data of vibration of the second direction in which associates as a set.

Furthermore, in the present invention, it is preferable that the maximum value among the average amplitudes of the respective blocks in the second direction is used for the evaluation of the uniformity in the circumferential direction of the golf club shaft in the third step.
Furthermore, in the present invention, the evaluation of the uniformity in the circumferential direction of the golf club shaft in the third step may use an average value obtained by averaging all the average amplitudes in the second direction of each block. preferable.
In the present invention, in the evaluation of the uniformity in the circumferential direction of the golf club shaft in the third step, the vertical axis represents the average amplitude in the first direction, and the horizontal axis represents the average amplitude in the second direction. In the coordinate system, a set of the average amplitude in the first direction of each block and the average amplitude in the second direction of each block obtained by measurement at each position is plotted as a point, and the first It is preferable that the size of a region formed between a line connecting the points in the block order in which vibration is started in the direction 1 and the vertical axis or the horizontal axis is used.

  Furthermore, in the present invention, it is preferable that the vibration in the first direction and the vibration in the second direction are acceleration vibrations, respectively.

  According to the golf club shaft evaluation method of the present invention, the golf club shaft is vibrated in a first direction orthogonal to the longitudinal direction of the golf club shaft, and vibration in the first direction is orthogonal to the first direction. Simultaneously measuring the vibration in the second direction, and rotating the golf club shaft relative to the first direction at a predetermined angle relative to the first direction with the central axis of the golf club shaft as the rotation center, Since the golf club shaft is simply vibrated in the first direction and the measurement of the vibration in the first direction and the vibration in the second direction is repeated at the same time, the uniformity in the circumferential direction of the golf club shaft is facilitated. Can be evaluated.

Hereinafter, a golf club shaft evaluation method of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1A is a schematic diagram showing a vibration measuring device used in the golf club shaft evaluation method of the present invention, and FIG. 1B is a first acceleration sensor in the vibration measuring device shown in FIG. FIG. 5 is a schematic diagram showing an enlarged mounting position of the second acceleration sensor.

As shown in FIG. 1, the vibration measuring device 10 measures the vibration of the golf club shaft 22, and includes a fixing portion 12 that fixes the golf club shaft 22 and a first vibration that detects the vibration of the golf club shaft 22. The acceleration sensor 14 and the second acceleration sensor 16, an FFT analyzer 18, and a computer (hereinafter referred to as PC) 20 are included.
In the golf club shaft evaluation method of the present invention, the type of the golf club shaft 22 to be evaluated is not particularly limited. As the golf club shaft 22 to be evaluated, for example, a carbon shaft and a steel shaft can be evaluated.

In the golf club shaft evaluation method of the present invention, for example, the rear end portion 24a of the golf club shaft 22 to be evaluated is fixed, the front end portion 24b is vibrated, and the vibration characteristics of the golf club shaft 22 are measured.
Here, when the golf club shaft 22 is attached to a golf club head (not shown) and used as a golf club (not shown), a grip (not shown) is attached to the rear end portion 24a of the golf club shaft 22. It is the end of the side to be used.
The front end portion 24b of the golf club shaft 22 is an end portion on the side attached to a golf club head (not shown). The length of the golf club shaft is 1170 mm, for example.

In the vibration measuring apparatus 10 of the present embodiment, the fixing portion 12 fixes the rear end portion 24a of the golf club shaft 22. The fixing portion 12 is provided on the horizontal plane B, for example. When the golf club shaft 22 is fixed to the fixing portion 12, the central axis C of the golf club shaft 22 is parallel to the horizontal plane B.
The length of the rear end portion 24a of the golf club shaft 22 in the fixed portion 12 is, for example, 170 mm.
The method for fixing the golf club shaft 22 of the fixing portion 12 is not particularly limited.

The first acceleration sensor 14 measures the vibration of the front end portion 24 b of the golf club shaft 22 in the vertical direction (first direction) V orthogonal to the longitudinal direction L of the golf club shaft 22. The vertical direction V is perpendicular to the horizontal plane B.
The first acceleration sensor 14 is, for example, at a position 30 mm away from the front end 22a of the golf club shaft 22 toward the rear end 24a side, and on the peripheral surface 22b of the golf club shaft 22 in the vertical direction V from the horizontal plane B. It is provided at the position where the distance is the farthest. In other words, the first acceleration sensor 14 is located at a position 30 mm away from the front end 22 a of the golf club shaft 22 toward the rear end portion 24 a and on the peripheral surface 22 b of the golf club shaft 22. It is provided on a line Y passing through C and parallel to the vertical direction V. The position where the first acceleration sensor 14 is provided is referred to as a first attachment position α.

The second acceleration sensor 16 measures the vibration of the front end portion 24 b of the golf club shaft 22 in the left-right direction (second direction) H orthogonal to the longitudinal direction L and the up-down direction V of the golf club shaft 22.
The second acceleration sensor 16 is provided at a position obtained by rotating the first acceleration sensor 14 by 90 ° about the central axis C of the golf club shaft 22. In other words, the second acceleration sensor 16 has a central axis of the golf club shaft 22 at a position 30 mm away from the front end 22a of the golf club shaft 22 toward the rear end portion 24a and on the peripheral surface 22b of the golf club shaft 22. It is provided on a line X passing through C and parallel to the horizontal direction H perpendicular to the longitudinal direction L and the vertical direction V. The position where the second acceleration sensor 16 is provided is referred to as a second attachment position β.

In the present embodiment, the golf club shaft 22 is subjected to free-damping vibration by applying a displacement of, for example, 20 mm to the front end 22a of the golf club shaft 22 in the downward direction _VL toward the horizontal plane B. At this time, the first acceleration sensor 14 and the second acceleration sensor 16 measure free damping vibration of the golf club shaft 22 as acceleration.

The FFT analyzer 18 is connected to the first acceleration sensor 14 and the second acceleration sensor 16, and takes in acceleration signals obtained from the first acceleration sensor 14 and the second acceleration sensor 16 in time series. Are output to the PC 20.
In the FFT analyzer 18, for example, the acceleration signal of the first acceleration sensor 14 and the acceleration signal of the second acceleration sensor 16 are each started to vibrate for 4 seconds with a sampling period of 1 millisecond (for example) Sampling time). The FFT analyzer 18 obtains time-series data (time waveform) of acceleration in the vertical direction V (first acceleration) by the first acceleration sensor 14, and acceleration in the horizontal direction H (second waveform) by the second acceleration sensor 16. Time-series data (time waveform).

Note that the sampling period of the acceleration signal by the FFT analyzer 18 is not limited to 1 millisecond, and can be appropriately changed according to the required measurement accuracy of vibration.
Furthermore, the acquisition time (sampling time) for the acceleration signal by the FFT analyzer 18 is not limited to 4 seconds, and can be changed as appropriate according to the characteristics of the golf club shaft 22 and the required vibration measurement accuracy. is there.

The PC 20 divides the time series data of the acceleration in the vertical direction V and the time series data of the acceleration in the left and right direction H from the FFT analyzer 18, for example, every 100 milliseconds, and divides this into one block. In this case, since the time waveform of 4 seconds is divided every 100 milliseconds, the time series data of acceleration in the vertical direction V and the time series data of acceleration in the horizontal direction H are each divided into 40 blocks. In the present embodiment, one block includes 100 acceleration signal values.
One block is not limited to 100 milliseconds, and can be appropriately changed according to the characteristics of the golf club shaft 22 and the required measurement accuracy of vibration.

Further, the PC 20 calculates the square root of the square sum of the acceleration signal values for each block of the time series data of the acceleration in the vertical direction V, and calculates the average acceleration in the vertical direction V (hereinafter referred to as the vertical average acceleration) for each block. )
Further, the square root of the sum of squares of the acceleration signal values is calculated for each block of the time series data of acceleration in the horizontal direction H, and the average acceleration in the horizontal direction H (hereinafter referred to as the horizontal average acceleration) is obtained for each block. .

In the PC 20, for example, when dividing the time series data of the vertical average acceleration (acceleration in the vertical direction V) and the time series data of the horizontal average acceleration (acceleration in the horizontal direction H) obtained by simultaneous measurement into 40 blocks, A number is assigned to each block, and the block of acceleration in the vertical direction V and the block of acceleration in the horizontal direction H are associated with each other as a set based on this number. Thus, the average acceleration in the vertical direction V of each block and the average acceleration in the horizontal direction H of each block can be associated as a set.
In this embodiment, as will be described later, one golf club shaft 22 is rotated in the circumferential direction θ to measure vibration. Since the measurement is repeated by rotating in the circumferential direction θ, the vibration level varies. For this reason, in order to standardize the initial displacement of the golf club shaft 22, in each measurement, the average acceleration of the first block immediately after the start of vibration in which the acceleration takes the maximum value is made uniform. In accordance with this, the average acceleration value of each block is normalized.

The PC 20 has a configuration similar to that of a general personal computer, and includes a CPU and a memory. An input unit used for computer input, such as a keyboard and a mouse, information input from the input unit, and information processing by the CPU And a display unit such as an LCD for displaying the recorded information.
Note that the PC 20 can also capture the acceleration signal of the first acceleration sensor 14 and the acceleration signal of the second acceleration sensor 16 by the FFT analyzer 18. In this case, an AD conversion board that AD converts the acceleration signal of the first acceleration sensor 14 and the acceleration signal of the second acceleration sensor 16 may be incorporated in the PC 20 and each acceleration signal may be directly taken into the computer 20.

Next, the golf club shaft evaluation method of this embodiment will be described by taking a carbon shaft having a length of 1170 mm as the golf club shaft 22 as an example.
2A to 2D are schematic views showing a method of measuring the vibration of the golf club shaft by the vibration measuring apparatus shown in FIG. 1 in the order of steps.

  First, the rear end portion 24a of the golf club shaft 22 is fixed to the fixing portion 12 of the vibration measuring device 10 shown in FIG. The fixing pressure of the golf club shaft 22 by the fixing portion 12 is, for example, 19.6 N (2 kgf).

Next, the first acceleration sensor 14 is mounted 30 mm from the tip 22a of the golf club shaft 22 and on the line Y passing through the central axis C on the peripheral surface 22b of the golf club shaft 22, that is, at the first mounting position α. .
The second acceleration sensor 16 is attached to a position rotated by 90 ° from the position of the first acceleration sensor 14 around the center axis C of the golf club shaft 22, that is, the second attachment position β.
Here, when evaluating the golf club shaft 22, when the vibration is first measured, for example, as shown in FIG. 2A, a mark 26 is attached to the tip 22 a of the golf club shaft 22. The position of the mark 26 is set as a reference position (first position), for example.

  In this embodiment, as will be described later, the golf club shaft 22 is rotated in the circumferential direction θ (see FIG. 2A) and vibration measurement is performed a plurality of times. However, even if the golf club shaft 22 rotates, the golf club shaft 22 rotates. The first attachment position α to which the first acceleration sensor 14 is attached and the second position β to which the second acceleration sensor 16 is attached do not change.

After fixing the rear end portion 24a of the golf club shaft 22 and attaching the first acceleration sensor 14 and the second acceleration sensor 16, the front end 22a of the golf club shaft 22 is displaced 20 mm downward _VL. , Release the tip 22a. Thereby, the front-end | tip part 24a of the golf club shaft 22 vibrates.
At this time, acceleration in the vertical direction V (hereinafter referred to as vertical acceleration) is measured by the first acceleration sensor 14, and acceleration in the horizontal direction H (hereinafter referred to as horizontal acceleration) is simultaneously measured by the second acceleration sensor 16. Each acceleration signal is output to the FFT analyzer 18 and taken into the FFT analyzer 18.

  In this embodiment, after releasing the tip 22a, the FFT analyzer 18 acquires an acceleration signal of 4 seconds (sampling time) with a sampling period of 1 millisecond, for example. Thereby, as shown in FIG. 3A at the first position, the time-series data of the vertical acceleration at the first position, and at the time of the lateral acceleration at the first position as shown in FIG. Series data is obtained.

Next, the first acceleration sensor 14 and the second acceleration sensor 16 are removed from the golf club shaft 22, and the golf club shaft 22 is removed from the fixing portion 12.
Next, as shown in FIG. 2B, the golf club shaft 22 is rotated by 45 ° in the circumferential direction θ from the reference position (first position) in FIG. The rear end portion 24 a of the golf club shaft 22 is fixed by the portion 12. This position is referred to as a second position.
Next, the first acceleration sensor 14 is attached to the first attachment position α, and the second acceleration sensor 16 is attached to the second attachment position β.
Then, after the tip 22a of the golf club shaft 22 is displaced 20 mm in the downward direction _VL , the tip 22a is released, and the tip 24a of the golf club shaft 22 is vibrated.
At this time, the vertical acceleration is measured simultaneously by the first acceleration sensor 14 and the lateral acceleration is measured simultaneously by the second acceleration sensor 16, and after the tip 22a is released to the FFT analyzer 18, for example, a sampling period of 1 millisecond is obtained. Thus, an acceleration signal for 4 seconds is acquired. Thereby, as shown in FIG. 3C, the time-series data of the vertical acceleration at the second position and the time-series data of the left-right acceleration at the second position are obtained as shown in FIG. .

Further, in the present embodiment, as shown in FIG. 2C, the golf club shaft 22 is rotated by 45 ° in the circumferential direction θ from the second position in FIG. This position is referred to as a third position.
Next, as described above, the first acceleration sensor 14 is attached to the first attachment position α, and the second acceleration sensor 16 is attached to the second attachment position β. Then, after the tip 22a of the golf club shaft 22 is displaced 20 mm in the downward direction _VL , the tip 22a is released, the tip 24a of the golf club shaft 22 is vibrated, and the vertical acceleration is caused by the first acceleration sensor 14. The left and right accelerations are simultaneously measured by the second acceleration sensor 16. After releasing the tip 22a from the FFT analyzer 18, for example, an acceleration signal of 4 seconds is acquired at a sampling period of 1 millisecond. As a result, as shown in FIG. 3E, the time-series data of the vertical acceleration at the third position and the time-series data of the left-right acceleration at the third position are obtained as shown in FIG. .

Furthermore, in the present embodiment, as shown in FIG. 2D, the golf club shaft 22 is rotated 45 ° in the circumferential direction θ from the position of FIG. This position is referred to as a fourth position.
Next, as described above, the first acceleration sensor 14 is attached to the first attachment position α, and the second acceleration sensor 16 is attached to the second attachment position β. Then, after the tip 22a of the golf club shaft 22 is displaced 20 mm in the downward direction _VL , the tip 22a is released, the tip 24a of the golf club shaft 22 is vibrated, and the vertical acceleration is caused by the first acceleration sensor 14. The left and right accelerations are simultaneously measured by the second acceleration sensor 16. After releasing the tip 22a from the FFT analyzer 18, for example, an acceleration signal of 4 seconds is acquired at a sampling period of 1 millisecond. Thereby, as shown in FIG. 3G, the time-series data of the vertical acceleration at the fourth position and the time-series data of the left-right acceleration at the fourth position as shown in FIG. 3H are obtained. .

  Next, for each time series data of the vertical acceleration shown in FIG. 3A, FIG. 3C, FIG. 3E and FIG. 3G obtained from the first position to the fourth position, The PC 20 divides the acceleration signal acquisition interval of the vertical acceleration into one block every 100 milliseconds, and divides it into a total of 40 blocks. Then, the square root of the sum of squares of the acceleration signal values is calculated for each block, and the average vertical acceleration is obtained for each block.

  Next, for each time series data of the left and right acceleration shown in FIG. 3 (b), FIG. 3 (d), FIG. 3 (f) and FIG. 3 (h) obtained at the first position to the fourth position, The PC 20 divides the acceleration signal acquisition interval of left and right acceleration as one block every 100 milliseconds, and divides it into a total of 40 blocks. And the square root of the square sum of the value of an acceleration signal is calculated about each block, and a left-right average acceleration is obtained for every block.

The vertical average acceleration and the horizontal average acceleration obtained in each block are set as a correspondence set. In this case, a number is assigned to each of the 40 blocks to be divided in order from immediately after the start of vibration, and the numbers are associated with each other as a set by matching the numbers with respect to the vertical average acceleration and the horizontal average acceleration. .
For example, as shown in FIG. 4, a set of vertical average acceleration and horizontal average acceleration obtained by each block and associated with a coordinate system in which the vertical axis is vertical average acceleration and the horizontal axis is horizontal average acceleration. Can be plotted as points.

In this embodiment, when the golf club shaft 22 is evaluated, for example, as shown in FIG. 4, the greater the lateral acceleration, the greater the lateral blur (the deformation characteristics differ in the circumferential direction of the golf club shaft 22). Can be evaluated.
Of the first position to the fourth position measured by rotating the golf club shaft 22 in the circumferential direction θ, the position where the left-right acceleration is the largest is the left-right shake (the deformation characteristics are different in the circumferential direction of the golf club shaft 22). Can be evaluated as a large area. Thereby, since the golf club shaft 22 can be evaluated in which direction the lateral blur occurs, it is possible to specify the direction in which the lateral blur (different deformation characteristics in the circumferential direction of the golf club shaft 22) occur. .
Thus, in this embodiment, the uniformity of the golf club shaft 22 in the circumferential direction of the golf club shaft 22 can be evaluated.
In the present embodiment, when evaluating the uniformity in the circumferential direction of the golf club shaft 22, it is only necessary to measure the vertical acceleration and the lateral acceleration of the tip portion 24 b of the golf club shaft 22. be able to.
In this embodiment, the golf club shaft 22 is rotated and the vibration is measured using the position of the mark 26 attached to the tip 22a of the golf club shaft 22 as the reference position (first position). However, the present invention is not limited to this, and the golf club shaft 22 is fixed, the vibration direction, that is, the vibration direction is changed with the position of the mark 26 of the golf club shaft 22 as the reference position, and the vibration is measured. May be changed.

In the present invention, the evaluation of the uniformity in the circumferential direction of the golf club shaft 22 may be performed using, for example, the maximum value of the average lateral acceleration of each block. In this case, regardless of the degree to which the golf club shaft 22 is rotated in the circumferential direction θ, the maximum value of the left and right average acceleration at the point shown in FIG. 4, that is, the value A ₁ of the left and right average acceleration at the point p ₁ is evaluated. .
Further, the evaluation of the uniformity in the circumferential direction of the golf club shaft 22 may be performed using, for example, an average value obtained by averaging all the left and right average accelerations of the respective blocks. In this case, the evaluation is performed by the average value of the left and right average acceleration in the plots of all points shown in FIG.

Furthermore, the evaluation of the uniformity in the circumferential direction of the golf club shaft 22 is, as shown in FIG. 4, when a set of vertical average acceleration and horizontal average acceleration is plotted as a point, For example, the size of the region formed between the vertical axis indicating the vertical average acceleration may be evaluated. For example, as shown in FIG. 4, it is obtained by measuring at a first position (◇ mark), a second position (□ mark), a third position (◯ mark), and a fourth position (♦ mark). among the various points it is, to evaluate the area of the largest region D _1.
This region D ₁ is a region formed between the longitudinal axis of the line m ₁ connected to each point obtained by measuring at a third position to block the order showing the upper and lower average acceleration.
Here, the block order is the order of numbers assigned to each block in order from the start of vibration when the time-series data of vertical acceleration or lateral acceleration is divided into blocks.

In addition, the evaluation of the uniformity in the circumferential direction of the golf club shaft 22 can be performed by plotting a combination of the vertical average acceleration and the horizontal average acceleration as points and connecting each point in block order, for example, the horizontal average acceleration. You may evaluate by the magnitude | size of the area | region formed between the horizontal axis | shafts shown.
Also in this case, for example, the evaluation is performed by the area of the largest region among various points obtained by measurement at the first position to the fourth position.

  Note that the evaluation method of the golf club shaft 22 of the present embodiment is not limited to the evaluation of the carbon shaft. For example, with respect to the steel shaft, similarly to the carbon shaft, the vertical acceleration and the horizontal acceleration are measured at the first position to the fourth position using the vibration measuring device 10, respectively, and FIGS. The time-series data (time waveform) of the vertical acceleration and the horizontal acceleration as shown in FIG.

For each time series data (time waveform) of the vertical acceleration and the horizontal acceleration, as described above, the square root of the square sum of the values of the acceleration signals is calculated for each block of the time series data of the vertical acceleration, and for each block, Get the average vertical acceleration. Further, the square root of the sum of squares of the acceleration signal values is calculated for each block of the time-series data of the lateral acceleration, and the lateral average acceleration is obtained for each block. And as above-mentioned, the group of the vertical average acceleration of each block and the horizontal average acceleration of each block is matched.
For example, as shown in FIG. 5, the vertical average acceleration and the horizontal average acceleration obtained in each block and associated as a set in a coordinate system in which the vertical axis is the vertical average acceleration and the horizontal axis is the horizontal average acceleration. Plot the tuple as a point.

  When evaluating a steel shaft as the golf club shaft 22, as shown in FIG. 5, as shown in FIG. 5, the larger the left / right average acceleration, the more the left / right shake (the deformation characteristics differ in the circumferential direction of the golf club shaft 22). ) Is large. Further, as described above, among the first position (□ mark), the second position (◇ mark), the third position (Δ mark), and the fourth position (+ mark) shown in FIG. From the position where the lateral acceleration is the largest, it is possible to specify in which direction the golf club shaft 22 is laterally shaken (the deformation characteristics are different in the circumferential direction of the golf club shaft 22).

Also for the steel shaft, as with the carbon shaft, regardless of the degree to which the golf club shaft 22 is rotated in the circumferential direction θ, the maximum value of the left and right average acceleration at the points shown in FIG. Of these, the maximum value), that is, the value A ₂ of the average lateral acceleration at the point p ₂ can be evaluated.
Further, for example, the uniformity in the circumferential direction of the golf club shaft 22 may be evaluated by using the average value of the average lateral acceleration of each block. In this case, regardless of the degree to which the golf club shaft 22 is rotated in the circumferential direction θ, the average value of the left and right average acceleration in all the plots shown in FIG. 5, that is, the average of all the average left and right accelerations of each block Evaluate using the value.

Furthermore, as shown in FIG. 5, when the set of the vertical average acceleration and the horizontal average acceleration is plotted as a point, between the line connecting the points in block order and the vertical axis indicating the vertical average acceleration, for example. You may evaluate by the magnitude | size of the area | region formed. In this case, for example, as shown in FIG. 5, a first position to fourth among various points obtained by measuring in a position to evaluate the area of the largest region D _2.
This region D ₂ is a region formed between the longitudinal axis the second position (◇ symbol) and the line m ₂ connected to each point obtained by measuring the block order by showing the upper and lower average acceleration.

In addition, the evaluation of the uniformity in the circumferential direction of the golf club shaft 22 can be performed by plotting a combination of the vertical average acceleration and the horizontal average acceleration as points and connecting each point in block order, for example, the horizontal average acceleration. You may evaluate by the magnitude | size of the area | region formed between the horizontal axis | shafts shown.
Also in this case, for example, the evaluation is performed by the area of the largest region among various points obtained by measurement at the first position to the fourth position.

  In addition, when the carbon shaft shown in FIG. 4 and the steel shaft shown in FIG. 5 are compared, the steel shaft has a smaller lateral average acceleration value and less variation. Good uniformity. Therefore, the evaluation of the uniformity in the circumferential direction by the golf club shaft evaluation method of the present invention is generally referred to as the left and right shake of the golf club shaft (the deformation characteristics differ in the circumferential direction of the golf club shaft). Consistent with the sensory evaluation of

  In the present embodiment, one golf club shaft 22 is rotated by 45 ° in the circumferential direction θ, and the vertical acceleration and the horizontal acceleration are measured a total of four times. However, the present invention is not limited to this. In the present embodiment, for example, it is preferable that the measurement range is a range of 180 ° from the initial measurement position of the golf club shaft 22, and in this range, the angle to be changed every measurement and the number of measurements are particularly It is not limited.

In the present embodiment, the first acceleration sensor 14 and the second acceleration sensor 16 are used. However, in the present invention, the vibration in the vertical direction V is measured at the first attachment position α with respect to the golf club shaft 22. If the vibration of the left-right direction H can be measured in the 2nd attachment position (beta), it will not be limited to this. Instead of the first acceleration sensor 14 and the second acceleration sensor 16, for example, a non-contact type vibration meter such as a laser Doppler vibration meter or an ultrasonic vibration meter can be used.
When a non-contact type vibrometer is used, it is not necessary to attach a mass body to the golf club shaft 22 as in the case of an acceleration sensor, so that vibrations in the vertical direction V and the horizontal direction H can be measured with higher accuracy. Can do.

When a non-contact type vibrometer is used in this way, the acceleration in the above-described embodiment is changed to a vibration amplitude value, the vertical acceleration is a vertical amplitude (amplitude value in the first direction), and the horizontal acceleration is a horizontal amplitude. (The amplitude value in the second direction).
Also, the vertical average amplitude (average amplitude in the first direction) can be obtained by calculating the square root of the sum of squares of the vertical amplitudes, and the horizontal average acceleration can be calculated by calculating the square root of the square sum of the left and right amplitudes. An amplitude (average amplitude in the second direction) is obtained. The vertical average amplitude corresponds to the vertical average acceleration of the present embodiment, and the horizontal average amplitude corresponds to the horizontal average acceleration of the present embodiment.
Although these points are different from the present embodiment, in the other respects, similarly to the present embodiment, based on the vertical average amplitude and the horizontal average amplitude, similarly to the vertical average acceleration and the horizontal average acceleration of the present embodiment, golf The uniformity in the circumferential direction of the club shaft can be evaluated.

In addition, when evaluating a golf club shaft, it is possible to evaluate with the maximum value of the left and right average amplitude (the maximum value of the left and right average amplitude of each block), and also evaluate with all the average values of the left and right average amplitude of each block. You can also
Furthermore, in the coordinate system in which the vertical axis is the vertical average amplitude and the horizontal axis is the horizontal average amplitude, when a set of the vertical average amplitude and the horizontal average amplitude is plotted as points, a line connecting the points in block order For example, the evaluation may be performed by the size of the region formed between the vertical axis indicating the vertical average amplitude. In this case, it evaluates by the area of the largest area | region among the various points obtained by measuring in the 1st position-the 4th position.
Further, when the set of the vertical average amplitude and the horizontal average amplitude is plotted as points, the size of the area formed between the line connecting the points in block order and the horizontal axis indicating the horizontal average amplitude, for example. You may evaluate it.
Also in this case, for example, the evaluation is performed by the area of the largest region among various points obtained by measurement at the first position to the fourth position.

In the present embodiment, the direction in which the golf club shaft 22 is vibrated is the downward direction _VL, and the first mounting position α of the first acceleration sensor 14 and the second mounting position β of the second acceleration sensor 16 are set. However, the present invention is not limited to this.
For example, the golf club shaft 22 is fixed without being rotated in the circumferential direction θ, and the first mounting position of the first acceleration sensor 14 and the second mounting position of the second acceleration sensor 16 are set on the golf club shaft 22. The center axis C is changed to a position rotated by a predetermined angle with respect to the rotation center, and is further displaced to the front end 22a of the golf club shaft 22 in the vertical direction with respect to the first mounting position α of the first acceleration sensor 14. You may make it vibrate.
Thus, in the present invention, the vibration in the direction in which the golf club shaft 22 is vibrated and the vibration in the direction orthogonal to the direction in which the golf club shaft 22 is vibrated can be measured, and the central axis C of the golf club shaft 22 is rotated. As a center, the golf club shaft 22 is rotated relative to the circumferential direction θ by a predetermined angle with respect to the direction to be vibrated, and the golf club shaft 22 is vibrated in a direction to be vibrated, and is orthogonal to the vibrating direction. As long as the vibration in the direction can be measured at the same time, the direction of the vibration and the measuring method are not particularly limited.

  The present invention is basically as described above. The golf club shaft evaluation method of the present invention has been described in detail above. However, the present invention is not limited to the above embodiment, and various improvements or modifications may be made without departing from the spirit of the present invention. Of course.

(A) is a schematic diagram which shows the vibration measuring device used for the evaluation method of the golf club shaft of this invention, (b) is the 1st acceleration sensor in the vibration measuring device shown to Fig.1 (a), and It is a schematic diagram which expands and shows the attachment position of a 2nd acceleration sensor. (A)-(d) is a schematic diagram which shows the measuring method of the vibration of the golf club shaft by the vibration measuring apparatus shown in FIG. 1 in order of a process. (A) is the time-series data of the vertical acceleration of the carbon shaft at the reference position obtained by the first acceleration sensor with the vertical axis representing the vertical acceleration and the horizontal axis taking time, and (b) the vertical axis Is the time-series data of the horizontal acceleration of the carbon shaft at the reference position obtained by the second acceleration sensor with the horizontal axis taking time and the horizontal axis taking time, and (c) shows the vertical acceleration on the vertical axis, The time series data of the vertical acceleration of the carbon shaft at the second position obtained by the first acceleration sensor with time on the axis, (d) is the horizontal acceleration on the vertical axis and time on the horizontal axis. The time series data of the left and right acceleration of the carbon shaft at the second position obtained by the second acceleration sensor, (e) is the first acceleration with the vertical axis representing the vertical acceleration and the horizontal axis representing the time. The time series data of the vertical acceleration of the carbon shaft at the third position obtained by the sensor, (f) is obtained by the second acceleration sensor with the horizontal axis on the vertical axis and the time on the horizontal axis. It is time series data of the lateral acceleration of the carbon shaft at the third position, and (g) is the fourth position obtained by the first acceleration sensor with the vertical axis representing the vertical acceleration and the horizontal axis representing the time. (H) is the time series data of the vertical acceleration of the carbon shaft, and (h) shows the horizontal acceleration of the carbon shaft at the fourth position obtained by the second acceleration sensor with the horizontal axis on the vertical axis and time on the horizontal axis. Time series data. It is a graph which shows the relationship between the vertical average acceleration and the horizontal average acceleration in the carbon shaft, with the vertical axis representing the vertical average acceleration and the horizontal axis representing the horizontal average acceleration. It is a graph which shows the relationship between the vertical average acceleration and the horizontal average acceleration in a steel shaft, with the vertical axis representing the vertical average acceleration and the horizontal axis representing the horizontal average acceleration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vibration measuring device 12 Fixed part 14 1st acceleration sensor 16 2nd acceleration sensor 18 FFT analyzer 20 Computer (PC)
22 golf club shaft 22a front end 24a rear end 24b front end 26 mark C central axis L longitudinal direction α first mounting position β second mounting position

Claims (7)

The golf club shaft is vibrated in a first direction orthogonal to the longitudinal direction of the golf club shaft, and the vibration in the first direction and the vibration in the second direction orthogonal to the first direction are simultaneously performed. Measuring process;
The golf club shaft is rotated relative to the first direction by a predetermined angle with respect to the first direction with the central axis of the golf club shaft as a rotation center, and the golf club shaft is rotated in the first direction. Repeatedly measuring the vibration in the first direction and the vibration in the second direction at the same time;
Evaluating the circumferential uniformity of the golf club shaft using a set of vibrations in the first direction and vibrations in the second direction measured at each position obtained by rotating the golf club shaft in the circumferential direction. A golf club shaft evaluation method comprising: One end of the golf club shaft is fixed, the other end is vibrated in a first direction orthogonal to the longitudinal direction of the golf club shaft, and the golf club shaft is vibrated in the first direction. A first step of simultaneously measuring vibrations in the first direction and the second direction perpendicular to the longitudinal direction of the golf club shaft for a predetermined time;
The golf club shaft is rotated about a predetermined angle in the circumferential direction and the golf club center axis is a center of rotation, and then the one end is fixed and the other end is vibrated in the first direction. A second step of repeatedly measuring the vibration of the golf club shaft in the first direction and the vibration of the golf club shaft in the second direction simultaneously for a predetermined time;
Uniformity in the circumferential direction of the golf club shaft is evaluated using a set of vibration in the first direction and vibration in the second direction measured at each position where the golf club shaft is rotated in the circumferential direction. And a third step of evaluating the golf club shaft. The combination of the vibration in the first direction and the vibration in the second direction in the third step is:
The time-series data of the vibrations in the first direction and the time-series data of the vibrations in the second direction obtained in the first step and the second step are respectively a plurality of times at predetermined time intervals. Divided into blocks,
The square root of the sum of squares of the vibration in the first direction is calculated for each block of the time-series data of the vibration in the first direction to obtain the average amplitude in the first direction, and each second Calculating the square root of the square sum of the vibrations in the second direction for each block of the time-series data of vibrations in the direction to obtain the average amplitude in the second direction;
The average amplitude in the first direction of each block of the time-series data of the vibration in the first direction measured at each position where the golf club shaft is rotated in the circumferential direction, and the vibration in the second direction 3. The golf club shaft evaluation method according to claim 2, wherein the average amplitude in the second direction of each block of the time series data is associated as a set.   The evaluation of the golf club shaft according to claim 3, wherein the evaluation of the uniformity in the circumferential direction of the golf club shaft in the third step uses the maximum value among the average amplitudes in the second direction of the respective blocks. Method.   4. The evaluation of the uniformity in the circumferential direction of the golf club shaft in the third step uses an average value obtained by averaging all average amplitudes in the second direction of each block. Evaluation methods.   In the evaluation of the uniformity in the circumferential direction of the golf club shaft in the third step, the vertical axis represents the coordinate system of the average amplitude in the first direction, and the horizontal axis represents the average amplitude in the second direction. Plotting a set of the average amplitude in the first direction of each block and the average amplitude in the second direction of each block obtained by measuring at positions, and starting vibration in the first direction 4. The golf club shaft evaluation method according to claim 3, wherein a size of a region formed between a line connecting the points in the order of the blocks and the vertical axis or the horizontal axis is used.   The golf club shaft evaluation method according to claim 1 or 2, wherein the vibration in the first direction and the vibration in the second direction are vibrations of acceleration, respectively.

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