JP4960687B2 - Method for measuring characteristic value of shaft for golf club - Google Patents

Description

The present invention relates to a method of measuring characteristics values Shah shift for a golf club.

The golf club includes a golf club shaft (hereinafter referred to as a shaft) and a golf club head (hereinafter referred to as a head) attached thereto. In the case of a golf club having a large head with a large moment of inertia, it is said that even if the golf ball is hit outside the center of the sweet spot of the head, the head is difficult to rotate in a horizontal plane, so the direction of the hit ball is said to be stable. ing.
By the way, the average player who swings with the face open and suffers from slicing controls the direction of the hit ball by returning the head at the time of hitting. However, since the large head is difficult to return due to its large moment of inertia, the hit ball is still sliced.
Therefore, it is considered that the direction of the hit ball can be improved by combining a large head and a pointed shaft (for example, see Patent Documents 1 to 5) so that the head can be easily returned.
JP-A-9-141754 JP-A-9-164600 JP-A-11-99229 JP-A-11-99230 JP 2004-290391 A

  However, combining a conventional tip-to-steer shaft with a large head with a large mass makes it easy to toe down when hitting the ball, and the location of the ball hitting on the face is not stable, resulting in excessive backspin or insufficient results. As a problem, the flight distance becomes unstable.

  The present invention has been made in view of the above circumstances, and since the toe-down at the time of hitting is suppressed, the hitting place on the face is stable, the backspin is not applied excessively, and the head is easy to return. It is an object of the present invention to provide a shaft suitable for a player who is given a feeling and a feeling of catching a ball and suffers from slicing. It is another object of the present invention to provide a suitable measurement method for measuring a characteristic value of a shaft that serves as an index of characteristics of a golf club.

The gist of the present invention is that an upper support jig and a lower support jig installed at a predetermined distance in the horizontal direction are arranged such that the position of the distance L (mm) from the narrow end of the small diameter portion of the shaft is in contact with the lower support jig. And after pinching and fixing the shaft so that the shaft axis is horizontal, a weight of a predetermined mass is applied to the large diameter portion of the shaft, and a bending displacement δ _L (mm) at a predetermined position on the shaft is measured. Measuring step to be performed, the position where the shaft contacts the lower support jig is moved to the large diameter side by a predetermined length, and the measuring step is repeated, and the bending displacement obtained in the measuring step and the repeating step The group (L, δ _L ) is defined as (x, y), and the (x, y) is divided into two groups of 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300. By the least square method using x, y), the following formula (1) and In the measuring method for characteristic values of the shaft; and a regression process of linear regression in 2).
In 100 ≦ x ≦ 175, y = −a ₁ x + b ₁ (1)
In 225 ≦ x ≦ 300, y = −a ₂ x + b ₂ (2)

“Measuring method of bending displacement δ _L (mm)”
The shaft is sandwiched and fixed so that the shaft of the golf club shaft is horizontal between the upper support jig and the lower support jig installed 50 mm apart in the horizontal direction. At this time, a position where the shaft is in contact with the lower support jig is a position having a distance L = 100 mm. Next, a weight of 2 kg is applied to a position 615 mm away from the lower support jig along the shaft axis, and a bending displacement δ ₁₀₀ (mm) at a position 700 mm away from the lower support jig along the shaft axis is measured. . Next, the position where the shaft comes into contact with the lower support jig is moved by 25 mm toward the large diameter side, and the bending displacement amounts δ ₁₂₅ , δ ₁₅₀ ,... At positions 700 mm away from the lower support jig along the shaft axis at that time. .., δ ₃₀₀ (mm) is repeatedly measured to obtain a bending displacement group (L, δ _L ) = (x, y).

  According to the present invention, since the toe down at the time of hitting is suppressed, the hitting place on the face is stable and the backspin is not applied excessively, and the head is easy to return. A shaft suitable for a player who is given and suffers from slicing can be provided. In addition, it is possible to provide a suitable measurement method for measuring a shaft characteristic value that serves as an index of the golf club characteristic.

Hereinafter, the present invention will be described in detail.
[shaft]
The shaft of the present invention is formed such that the outer diameter of the surface perpendicular to the axial direction increases from one end to the other end in the length direction. Hereinafter, the end portion on the side having a smaller outer diameter is referred to as a small diameter end portion, and the end portion on the side having a larger outer diameter is referred to as a large diameter end portion. Further, from the center in the longitudinal direction of the shaft, the small diameter end portion side is referred to as a thin diameter portion, and the large diameter end portion side is referred to as a large diameter portion.

The shaft of the present invention has a bending displacement group (L, L) consisting of a distance L (mm) every 25 mm from the narrow end and a bending displacement δ _L (mm) at the position of the distance L measured by the following measuring method. δ _L ) is (x, y), which is divided into two groups of 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300, and the minimum two using all (x, y) respectively. the multiplication, when the linear regression in the following equation (1) and (2), one is a square R ₂ ² of the correlation coefficient of the square R ₁ ² and formula of the correlation coefficient of the formula (1) (2) Is 0.95 or more and satisfies the relationship of the following formula (3).
In 100 ≦ x ≦ 175, y = −a ₁ x + b ₁ (1)
In 225 ≦ x ≦ 300, y = −a ₂ x + b ₂ (2)
a ₁ / a ₂ ≧ 0.8 (3)

When the square R ₁ ² of the correlation coefficient in Expression (1) is 0.95 or more, the rigidity distribution in the vicinity of the head mounting position of the shaft (100 ≦ x ≦ 175) is uniform, and there are no spots. Further, when the square R ₂ ² of the correlation coefficient in Expression (2) is 0.95 or more, the rigidity distribution in the portion of the shaft where 225 ≦ x ≦ 300 is uniform, and there are no spots. Therefore, when both R ₁ ² and R ₂ ² are 0.95 or more, the effects described later when the relationship of the expression (3) is satisfied are sufficiently exhibited.

As shown in the formula (3), when the ratio of a ₁ and a ₂ (a ₁ / a ₂ ) is 0.8 or more, toe down at the time of hitting is suppressed, the head easily returns, and slicing hardly occurs. It can be a shaft. According to such a shaft, for example, even when a large head with a large moment of inertia having a volume exceeding 350 ml is mounted, a golf ball can be hit directly in front of the face without removing the sweet spot at the time of hitting. It is possible to obtain a golf club with a running feeling and a feeling of catching the ball.

_Further, each of the preferred ranges of _a 1, _{a 2} are both 0.05~0.3 [mm / mm], the preferred range of the ratio of the _{a 1} and _{a 2 (a 1 / a 2} ) is It is the range of following formula (4). Within such a range, the feeling of catching the ball is further improved.
6 ≧ a ₁ / a ₂ ≧ 0.8 (4)

In the present invention, as described above, the bending displacement group (L, δ _L ) is divided into two groups of 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300. Linear regression is performed by the square method. This is because the study by the inventor has revealed that it is important to obtain the effect of the present invention that the tendency of the shaft stiffness changes at the boundary of 175 <x <225. is there. Therefore, in the present invention, the bending displacement group (L, δ _L ) is divided into two groups of 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300, and the rigidity of the shaft is studied. did.
Further, in the portion where x is less than 100 mm, 30 to 100% of the portion later becomes a bonded portion with the head, and therefore the rigidity of this portion has a very small influence on the characteristics of the shaft. Therefore, the present invention does not consider the rigidity and bending displacement of this part.

Next, a method for measuring the bending displacement δ _L (mm) at the distance L (mm) on the shaft will be described with reference to FIG. In FIG. 1, the vertical direction is the vertical direction, and the horizontal direction is the horizontal direction.
First, a pair of upper support jig 11 and lower support jig 12 for sandwiching the shaft 10 is prepared, and these are installed with a distance A = 50 mm apart from each other in the horizontal direction. Next, the upper support jig 11 and the lower support jig 12 are sandwiched and fixed so that the axis of the shaft 10 is horizontal. At this time, the position of 100 mm from the small diameter end of the shaft 10, that is, the position of the distance L = 100 mm is brought into contact with the lower support jig 12. Next, a weight 13 having a mass of 2 kg is applied from the lower support jig 12 along the axis of the shaft 10 by a distance B = 615 mm, and is separated from the lower support jig 12 by a distance C = 700 mm along the axis of the shaft 10. The displacement amount of the position is measured by the measuring instrument 14, and the value is set as a bending displacement amount δ ₁₀₀ (mm) at a distance L = 100 mm (measurement step).
Then, by moving the shaft 10 by 25 mm in the direction of the arrow, the position where the shaft 10 is in contact with the lower support jig 12 is moved 25 mm to the larger diameter side, that is, the distance L is increased by 25 mm, and the lower support at that time Each bending displacement amount δ ₁₂₅ , δ ₁₅₀ ,..., Δ ₃₀₀ (mm) of the shaft at a position 700 mm away from the jig 12 along the axis of the shaft 10 is similarly measured by the measuring instrument 14, and a bending displacement group is obtained. (L, δ _L ) = (x, y) = (100, δ ₁₀₀ ), (125, δ ₁₂₅ ), (150, δ ₁₅₀ ),..., (300, δ ₃₀₀ ) are obtained (iterative process). . At this time, the position at which the weight 13 is applied is also moved by 25 mm in accordance with the movement of the shaft 10 and the distance B is always measured to be 615 mm.

Next, the bending displacement group (L, δ _L ) thus obtained in the measurement step and the iteration step is linearly regressed on two straight lines.
Specifically, the bending displacement group (L, δ _L ) obtained in the measurement step and the iteration step is set to (x, y), and this bending displacement group is defined as 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300. Are divided into two groups, respectively, and linear regression is performed to the following formulas (1) and (2) by the least square method using all (x, y) (regression step).
In 100 ≦ x ≦ 175, y = −a ₁ x + b ₁ (1)
In 225 ≦ x ≦ 300, y = −a ₂ x + b ₂ (2)

That is, when there are n data, (X ₁ , Y ₁ ), (X ₂ , Y ₂ ), (X ₃ , Y ₃ ),..., (X _n , Y _n ), It is generally known that a and b in the straight line Y = aX + b and the square R ^{2 of the} correlation coefficient are obtained (least square method). Therefore, by advancing to two straight lines (the above formulas (1) and (2)) with (L, δ _L ) as (x, y) along this, a ₁ , b _1, a ₂ , ^{_{b 2, R 1 2, R}} 2 2 is obtained, respectively.

As described above, the bending displacement group is divided into two groups of 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300, and the least square method using all (x, y) is used. When linear regression is performed on the equations (1) and (2), the square R ₁ ² of the correlation coefficient of the equation (1) and the square R ₂ ² of the correlation coefficient of the equation (2) are both 0.95 or more. In addition, according to the shaft satisfying the relationship of the formula (3), the toe down at the time of hitting is suppressed, so that the hitting place on the face is stable and the backspin is not applied excessively, and the head can be easily returned. Therefore, it is possible to provide a shaft suitable for a player who suffers from slicing by giving a feeling of running of the head and a feeling of catching the ball.

There is no restriction | limiting in particular in the material of such a shaft of this invention, For example, the thing made from fiber reinforced resin which consists of matrix resins, such as an epoxy resin, and reinforced fibers, such as carbon fiber, is mentioned.
Further, the shaft production method of the present invention is not particularly limited, but in the case of a fiber reinforced resin, a sheet-like prepreg in which an uncured matrix resin is impregnated in a reinforced fiber is prepared, and this prepreg is formed into a rod shape. There is a so-called sheet wrap method in which a core metal (mandrel) is wound and then cured to extract the core metal.
In the sea trap method, it is common to prepare a plurality of types of prepregs having different areas and orientations of the reinforcing fibers contained therein, and sequentially winding them one by one on a core bar to produce a multi-layered shaft. However, at this time, by adjusting the area of each prepreg, the direction of the reinforcing fiber contained in each prepreg, the position where each prepreg is wound, or by changing the number of layers of the prepreg, A shaft can be manufactured. At this time, adjusting the degree of taper of the shaft and the outer diameter of the shaft as appropriate is also effective in manufacturing the shaft of the present invention.
Further, the shaft of the present invention may be formed of a partially different material, for example, by making the material of the portion of 175 <x <225 different from the portion of x ≦ 175 or x ≧ 225. Each part may have a desired rigidity.

The length, mass and the like of the shaft can be appropriately set, but the length is particularly preferably in the range of 990 to 1219 mm.
In addition, the shaft obtained in this manner is cut at the small diameter end side and the large diameter end side as necessary, and then the head is mounted on the small diameter side and the grip is mounted on the large diameter side. Is done. Here, when cutting a small-diameter end or a large-diameter end, if the cut length of the small-diameter end is 50 mm or less and the cut length of the large-diameter end is 229 mm or less, these cuts are characteristics of the shaft. The influence on the can be almost ignored.

[Measuring method of shaft characteristic value]
As shown in FIG. 1, the method for measuring the characteristic value of the shaft of the present invention includes an upper support jig 11 and a lower support jig 12 that are installed at a predetermined distance in the horizontal direction. After the shaft 10 is sandwiched and fixed so that the position of the distance L (mm) from the lower support jig 12 is in contact with the lower support jig 12 and the axis of the shaft 10 is horizontal, a weight having a predetermined mass is attached to the large-diameter portion of the shaft 10. And measuring the bending displacement amount δ _L (mm) at a predetermined position on the shaft, and moving the position where the shaft contacts the lower support jig to the large diameter side by a predetermined length to increase the distance L. The bending displacement group (L, δ _L ) obtained in the repetition process of repeating the measurement process and the measurement process and the repetition process is defined as (x, y), and 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300. Divided into two groups and each of them (X, y) by the least square method using, and a regression process of linear regression in the following equation (1) and (2).
In 100 ≦ x ≦ 175, y = −a ₁ x + b ₁ (1)
In 225 ≦ x ≦ 300, y = −a ₂ x + b ₂ (2)

Specifically, as described for the shaft 10 of the present invention, the distance between the upper support jig 11 and the lower support jig 12 is set to, for example, A = 50 mm, and the distance between the small diameter portions of the shaft 10 is set, for example. First, the shaft 10 is fixed so that the position of L = 100 mm is in contact with the lower support jig 12. Next, a weight having a mass of 2 kg, for example, is placed at a position separated by a distance B = 615 mm along the axis of the shaft 10 from the large diameter portion of the shaft 10, for example, the lower support jig 12, and along the axis of the shaft 10 from the lower support jig 12. For example, a displacement amount at a position separated by a distance C = 700 mm is measured by the measuring instrument 14, and the value is set as a bending displacement amount δ ₁₀₀ (mm) at a distance L = 100 mm (measurement step).
Then, the position where the shaft 10 is in contact with the lower support jig 12 is moved to the large diameter side, for example, by 25 mm, and each bending displacement amount of the shaft at a position 700 mm away from the lower support jig 12 along the axis of the shaft 10 at that time. δ ₁₂₅ , δ ₁₅₀ ,..., δ ₃₀₀ (mm) are measured, and the bending displacement group (L, δ _L ) = (x, y) = (100, δ ₁₀₀ ), (125, δ ₁₂₅ ), ( 150, δ ₁₅₀ ),..., (300, δ ₃₀₀ ) are obtained (iterative process).

Next, the bending displacement group (L, δ _L ) obtained in the measurement process and the iterative process is set to (x, y), and this is divided into two groups of 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300. Dividing into groups, linear regression is performed to equations (1) and (2) by the least square method using all of (x, y) (regression process).

Then, the obtained values of a ₁ , b _1, a ₂ , b _{2 and} the values of the squares of correlation coefficients R ₁ ² , R ₂ ² are used as shaft characteristic values, and this is used as an index from this shaft. The characteristics of the obtained golf club can be estimated.
Specifically, the squares R ₁ ² and R ₂ ² of the correlation coefficient are both 0.95 or more, and the ratio (a ₁ / a ₂ ) between a ₁ and a ₂ is 0.8 or more. The toe down at the time of hitting can be suppressed, the head can be easily returned, and the shaft can be hardly sliced.
According to such a shaft, for example, even when a large head with a large moment of inertia having a volume exceeding 350 ml is mounted, a golf ball can be hit directly in front of the face without removing the sweet spot at the time of hitting. It is possible to obtain a golf club with a running feeling and a feeling of catching the ball.

Hereinafter, the present invention will be described more specifically based on examples.
Example 1
A cored bar 20 (made of iron) having the shape shown in FIG. The outer diameter, length, and taper degree of each part in the cored bar 20 are as follows.
The outer diameter of P ₁ = 4.25 mm, the outer diameter of the _{P 3} = _7.10mm, outer diameter = 13.00Mm of _{P 4} and _{P 5,} the distance _{P 1 ~P 2 (l 1)} = 150mm, P 2 ~ P ₃ distance (l ₂ ) = 100 mm, P _{1 to} P ₄ distance (l ₃ ) = 960 mm, P _{1 to} P ₅ distance (l ₄ ) = 1500 mm, P _{1 to} P ₂ taper degree = 8. 30/1000, the degree of taper of P _{3 to} P ₄ = 8.30 / 1000

Next, prepregs (patterns 1 to 6) cut into the shape shown in FIG. 3 were sequentially wound around the metal core 20, and a polypropylene shrink tape having a width of 20 mm was wound thereon at a pitch of 2 mm.
Each of the patterns 2 and 3 is obtained by superposing two prepregs in which carbon fibers (CF) are oriented at + 45 ° and −45 ° with respect to the axial direction of the cored bar. In the pattern 2, the two winding start ends (upper end in the figure of the prepreg) are overlapped so as to be shifted by 9 mm at the left end in FIG. 3 of the pattern 2, and at the right end in FIG. The winding start ends of the sheets are stacked so as to be displaced by 20 mm. Moreover, the size of each part in FIG. 3 is as follows.
α ₁ = 200 mm, α ₂ = 44 mm, α ₃ = 100 mm, α ₄ = 60 mm, α ₅ = 1190 mm, α ₆ = 67 mm, α ₇ = 149 mm, α ₈ = 600 mm, α ₉ = 22 mm, α ₁₀ = 37 mm, α ₁₁ = 1190 mm, α ₁₂ = 45 mm, α ₁₃ = 97 mm, α ₁₄ = 1190 mm, α ₁₅ = 48 mm, α ₁₆ = 99 mm, α ₁₇ = 110 mm, α ₁₈ = 100 mm, α ₁₉ = 500 mm
In addition, the position where the prepreg is wound around the cored bar 20 is a portion from 50 mm to 1240 mm as measured from the narrow end.

  Next, this was placed in a heating furnace heated to 135 ° C. for 2 hours, taken out and cooled to room temperature, and then the shrink tape was peeled off and the surface was polished to obtain a shaft. The details of each prepreg used are as shown in Table 1.

With respect to this shaft, the bending displacement group (L, δ _L ) is obtained in accordance with the above-described “measurement method of bending displacement δ _L (mm)” described with reference to FIG. 1, and this is defined as (x, y). It is divided into two groups of 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300, and each of the equations (1) and (2) is linearized by the least square method using all (x, y). Regressed. In FIG. 1, A = 50 mm, B = 615 mm, C = 700 mm, the mass of the weight was 2 kg, and the shaft was moved by 25 mm in the direction of the arrow for measurement.
Table 2 shows the obtained values of a ₁ , a ₂ , R ₁ ² , R ₂ ² , a ₁ / a ₂ , the shaft length, mass, frequency, torque, and kick point.
The relationship between L and [delta] _L, L and relationship between the outer diameter, L and EI, respectively showing the relationship between the values 4, 5, 6.

Next, the obtained shaft was cut to a length of 44 inches (1118 mm), and then a head (volume: 400 ml, loft: 9 degrees) on the small diameter side and a commercially available grip on the large diameter side were mounted. A 75 inch (1137 mm) test driver golf club was manufactured. At this time, the cut length of the small diameter end portion was 0 mm, and the cut length of the large diameter end portion was 50 mm.
Three senior golfers hit the club five times each and calculated the average value by calculating the ball rotation, flight distance, etc. using “Science Eye Field” manufactured by Bridgestone Sports Co., Ltd. The results are shown in Table 3.

(1) Frequency It measured by the method described in Unexamined-Japanese-Patent No. 10-225541.
That is, using a golf club timing harmonizer manufactured by Fujikura Rubber Co., Ltd., a weight of 196 g simulating the head was attached to the tip (small diameter end) of the shaft, and 180 mm from the large diameter end of the shaft was fixed. The natural frequency was obtained.
(2) Kick point The kick point was determined by the method described in JP-A-10-225541.
In other words, the determined kick point position (length from the tip end, that is, the length from the small diameter end) was expressed as a ratio to the total shaft length using a fourteen kick point gauge FG-105RM.
(3) Torque (twist angle of the entire shaft)
It was measured according to the torque (twist angle of the entire shaft) measuring method described in JP-A-5-337223.
That is, the small-diameter end portion and the large-diameter end portion were each clamped with a chuck, and twisting torques (13.9 kgcm) in opposite directions were applied to the shaft via each chuck to measure the twist angle.
(4) EI distribution The EI value of the shaft was determined by the method described in JP-A-2001-120696.
That is, the shaft was supported at a distance of 300 mm between the fulcrums, a load of 20 kg was applied to the position of the distance L (mm) from the small diameter end of the shaft, and the bending deflection (mm) at the distance L (mm) was obtained. Then, the distance between the fulcrums is a (mm), the load is b (kg), the amount of bending deflection is c (mm), and from these values, the EI value [kgf · mm ² ] at the distance L (mm) is calculated by the following formula. Asked.
EI value = (1/48) × (b · a ³ / c)
(5) Measurement of outer diameter The outer diameter at a shaft distance L = 0 to 350 mm was measured at intervals of 25 mm using a micrometer.

(Comparative Example 1)
A shaft was obtained in the same manner as in Example 1 except that the prepreg (patterns 1 to 6) cut into the shape shown in FIG. 7 was used, and the same processing as in Example 1 was performed.
Pattern 2 is obtained by superposing two prepregs in which carbon fibers are oriented at + 45 ° with respect to the axial direction of the core metal and prepregs oriented at −45 °. At the end, the two winding start ends are overlapped so as to be shifted by 9 mm, and at the end on the right side in FIG. 7, the two winding start ends are overlapped so as to be shifted by 20 mm. Moreover, the size of each part in FIG. 7 is as follows.
α ₂₀ = 200 mm, α ₂₁ = 63 mm, α ₂₂ = 100 mm, α ₂₃ = 84 mm, α ₂₄ = 1190 mm, α ₂₅ = 67 mm, α ₂₆ = 149 mm, α ₂₇ = 300 mm, α ₂₈ = 22 mm, α ₂₉ = 220 mm, α ₃₀ = 29 mm, α ₃₁ = 1190 mm, α ₃₂ = 46 mm, α ₃₃ = 97 mm, α ₃₄ = 1190 mm, α ₃₅ = 48 mm, α ₃₆ = 99 mm, α ₃₇ = 110 mm, α ₃₈ = 100 mm

Table 2 shows the obtained values of a ₁ , a ₂ , R ₁ ² , R ₂ ² , a ₁ / a ₂ , the shaft length, mass, frequency, torque, and kick point.
The relationship between L and [delta] _L, L and relationship between the outer diameter, L and EI, respectively showing the relationship between the values 9, 10, shown in FIG. 11.
Then, a test driver golf club was produced from this shaft in the same manner as in Example 1, the ball rotation, flight distance, etc. were calculated, and the average value was obtained. The results are shown in Table 3.

なお、サイドスピンは、正がスライス回転、負がフック回転である。

The side spin is positive for slice rotation and negative for hook rotation.

(Example 2)
A cored bar (made of iron) 30 having the shape shown in FIG. The outer diameter, length, and taper degree of each portion of the core metal 30 are as follows.
The outer diameter of P ₁ = 4.10 mm, the outer diameter of P ₃ = 7.05 mm, the outer diameter of P ₄ and P ₅ = 13.00 mm, the distance (l ₁ ) of P _{1 to} P ₂ = 170 mm, P ₂ to P ₃ distance (l ₂ ) = 90 mm, P _{1 to} P ₄ distance (l ₃ ) = 960 mm, P _{1 to} P ₅ distance (l ₄ ) = 1500 mm, P _{1 to} P ₂ taper degree = 8. _50/1000, P 3 ~P ₄ taper degree = 8.50 / 1000

Next, a prepreg (patterns 1 to 6) cut into the shape shown in FIG. 8 was wound around the core 30 and a polypropylene shrink tape having a width of 20 mm was wound on the prepreg at a pitch of 2 mm.
Pattern 2 is obtained by superposing two prepregs in which carbon fibers are oriented at + 45 ° with respect to the axial direction of the core metal and prepregs oriented at −45 °. At the end, the two winding start ends are overlapped so as to be displaced by 9 mm, and at the right end in FIG. 8, the two winding start ends are overlapped so as to be shifted by 20 mm. Moreover, the size of each part in FIG. 8 is as follows.
α ₄₀ = 210 mm, α ₄₁ = 45 mm, α ₄₂ = 120 mm, α ₄₃ = 62 mm, α ₄₄ = 1190 mm, α ₄₅ = 63 mm, α ₄₆ = 143 mm, α ₄₇ = 300 mm, α ₄₈ = 21 mm, α ₄₉ = 220 mm, α ₅₀ = 29 mm, α ₅₁ = 1190 mm, α ₅₂ = 42 mm, α ₅₃ = 97 mm, α ₅₄ = 1190 mm, α ₅₅ = 46 mm, α ₅₆ = 99 mm, α ₅₇ = 140 mm, α ₅₈ = 130 mm
In addition, the position where the prepreg is wound around the core metal 30 was a portion from 50 mm to 1240 mm as measured from the end of the small diameter.

  Next, this was placed in a heating furnace heated to 135 ° C. for 2 hours, taken out and cooled to room temperature, and then the shrink tape was peeled off and the surface was polished to obtain a shaft. The details of the prepreg used are as shown in Table 2.

This shaft, in the same manner as in Example 1 _to obtain the values of ^{_{a 1, a 2, R 1}} 2, R 2 2, a 1 / a 2. Table 4 shows these values, shaft length, mass, frequency, torque, and kick point.
The relationship between L and [delta] _L, L and relationship between the outer diameter, L and EI, respectively showing the relationship between the values 9, 10, shown in FIG. 11.

Next, the obtained shaft was cut to a length of 44 inches (1118 mm), a head (volume: 460 ml, loft: 10 degrees) on the small diameter side, and a commercially available grip on the large diameter side, and a length of 45 inches. A driver golf club for a test of (1143 mm) was manufactured. At this time, the cut length of the small diameter end portion was 0 mm, and the cut length of the large diameter end portion was 50 mm.
This club was hit with 10 balls each using a golf trial hitting robot “SHOTROBO IV” manufactured by Miyamae Co., Ltd., and the average value was obtained by calculating the rotation, flight distance, etc. of the balls using “AccuVector” manufactured by AccuSport. . The results are shown in Table 5.

(Example 3 and Comparative Example 2)
In Example 3, the prepreg (patterns 1 to 6) cut into the shape shown in FIG. 12 was used. In Comparative Example 2, the prepreg (patterns 1 to 6) cut into the shape shown in FIG. 13 was used. The shaft was obtained in the same manner as in No. 2, and the same treatment as in Example 2 was performed.
Note that pattern 2 in FIG. 12 is obtained by superposing two prepregs in which carbon fibers are oriented at + 45 ° and −45 ° with respect to the axial direction of the cored bar. In the middle left end, the two winding start ends are overlapped so as to be shifted by 9 mm, and in the right end in FIG. 12, the two winding start ends are overlapped so as to be shifted by 20 mm. Moreover, the size of each part in FIG. 12 is as follows.
α ₆₀ = 210 mm, α ₆₁ = 29 mm, α ₆₂ = 120 mm, α ₆₃ = 40 mm, α ₆₄ = 1190 mm, α ₆₅ = 63 mm, α ₆₆ = 143 mm, α ₆₇ = 300 mm, α ₆₈ = 21 mm, α ₆₉ = 220, α ₇₀ = 29 mm, α ₇₁ = 1190 mm, α ₇₂ = 42 mm, α ₇₃ = 97 mm, α ₇₄ = 1190 mm, α ₇₅ = 46 mm, α ₇₆ = 99 mm, α ₇₇ = 150 mm, α ₇₈ = 135 mm

Pattern 2 in FIG. 13 is obtained by superposing two prepregs in which carbon fibers are oriented at + 45 ° with respect to the axial direction of the core metal and prepregs oriented at −45 °. The two winding start ends are overlapped so as to be shifted by 9 mm, and the two winding start ends are overlapped so as to be shifted by 20 mm in FIG. Moreover, the size of each part in FIG. 13 is as follows.
α ₈₀ = 210 mm, α ₈₁ = 45 mm, α ₈₂ = 120 mm, α ₈₃ = 62 mm, α ₈₄ = 1190 mm, α ₈₅ = 63 mm, α ₈₆ = 143 mm, α ₈₇ = 300 mm, α ₈₈ = 21 mm, α ₈₉ = 220 mm, α ₉₀ = 29 mm, α ₉₁ = 1190 mm, α ₉₂ = 42 mm, α ₉₃ = 97 mm, α ₉₄ = 1190 mm, α ₉₅ = 46 mm, α ₉₆ = 99 mm, α ₉₇ = 140 mm, α ₉₈ = 130 mm

Table 4 shows the obtained values of a ₁ , a ₂ , R ₁ ² , R ₂ ² , a ₁ / a ₂ , the shaft length, mass, frequency, torque, and kick point.
The relationship between L and [delta] _L, L and relationship between the outer diameter, L and EI, respectively showing the relationship between the values 9, 10, shown in FIG. 11.
Then, a test driver golf club was produced from this shaft in the same manner as in Example 2, and the rotation, flight distance, and the like of the ball were calculated, and the average value was obtained. The results are shown in Table 5.

なお、サイドスピンは、正がスライス回転、負がフック回転である。

The side spin is positive for slice rotation and negative for hook rotation.

As is clear from the results of Tables 2 to 5, according to the golf clubs obtained from the shafts of the examples, good head speed, ball speed, and flight distance are obtained, and the degree of backspin is moderate. In addition, the side spin is suppressed, and a shaft suitable for a player who suffers from slicing can be provided.
It was also shown that the characteristics of the golf club provided with this shaft can be estimated using the obtained values of a ₁ / a ₂ and the squares of correlation coefficients R ₁ ² and R ₂ ² as indices.

It is the schematic which shows the measuring method of bending displacement (delta) _L (mm) in this invention. It is a top view which shows the shape of the metal core used in the Example. It is a pattern figure which shows the shape of a prepreg (Example 1). It is a graph which shows the relationship between L and (delta) _L (Example 1, comparative example 1). It is a graph showing the relationship between L and an outer diameter (Example 1, comparative example 1). It is a graph showing the relationship between L and EI value (Example 1, comparative example 1). It is a pattern figure which shows the shape of a prepreg (comparative example 1). It is a pattern figure which shows the shape of a prepreg (Example 2). It is a graph showing the relationship between L and (delta) _L (Example 2, Example 3, comparative example 2). It is a graph showing the relationship between L and an outer diameter (Example 2, Example 3, comparative example 2). It is a graph showing the relationship between L and EI value (Example 2, Example 3, comparative example 2). (Example 3) which is a pattern figure which shows the shape of a prepreg. It is a pattern figure which shows the shape of a prepreg (comparative example 2).

Explanation of symbols

10 Shaft 11 Upper support jig 12 Lower support jig 13 Weight

Claims (1)

The upper support jig and the lower support jig installed in the horizontal direction separated by a predetermined distance, the position of the distance L (mm) from the narrow end of the narrow diameter portion of the golf club shaft is in contact with the lower support jig, and The golf club shaft is clamped and fixed so that the axis of the golf club shaft is horizontal, and then a weight of a predetermined mass is applied to the large diameter portion of the golf club shaft, and the golf club shaft is bent at a predetermined position on the golf club shaft. A measuring step for measuring the displacement δ _L (mm);
A step of repeating the measurement step by moving the position where the golf club shaft is in contact with the lower support jig to the large diameter side by a predetermined length; and
The bending displacement group (L, δ _L ) obtained in the measurement step and the repetition step is defined as (x, y), and the (x, y) is defined as 100 ≦ x ≦ 175 and 225 ≦ x ≦ 300. Divided into two groups, each having a regression step in which linear regression is performed to the following formulas (1) and (2) by the least square method using all (x, y) Measuring method of characteristic value of shaft for golf club.
In 100 ≦ x ≦ 175, y = −a ₁ x + b ₁ (1)
In 225 ≦ x ≦ 300, y = −a ₂ x + b ₂ (2)

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