JP2008148757A - Shaft for golf club and golf club - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft for a golf club excellent in carry performance and direction characteristics of a hit ball, and the golf club. <P>SOLUTION: Points T(1) to T(10) are obtained by plotting flexural rigidity EI at 10 points sequentially from a head. A straight line K passing through the T(1) and the T(10) satisfies an expression: [Y=aX+b1]. The values b2 to b9 represent Y-intercept values of straight lines, each of which is parallel with the straight line K and passes through each of the points T(2) to T(9), and the value bmin represents the minimum value of the Y-intercept values b2 to b9. A slope [a] of the line K is 0.04-0.06, and the values b3, b4, b5, b6, b7 and b8 are smaller than the value b1. The value bmin is one of the values b4 to b7. The value (b1-bmin) is in a range between 30 (N m<SP>2</SP>) and 40 (N m<SP>2</SP>). The value (b9-b1) is in a range between 4 to 15 (N m<SP>2</SP>). The shaft has a textile layer which has fiber in an axial direction and fiber in a circumferential direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a golf club shaft and a golf club.

  In recent years, so-called carbon shafts are frequently used as shafts for golf clubs. Carbon fibers having high specific strength and specific rigidity are used for the carbon shaft. As the specific strength and specific rigidity of the carbon fiber increase, it is possible to manufacture a golf club shaft that is reduced in weight.

During the swing, the shaft bends and twists. The behavior of the shaft during the swing can vary depending on the stiffness distribution of the shaft. Japanese Patent Application Laid-Open Nos. 2003-169871 and 2005-34550 disclose shafts in which rigidity distribution is considered. The invention described in Japanese Patent Application Laid-Open No. 2003-169871 defines the rigidity at the tip of the shaft. Japanese Patent Laying-Open No. 2005-34550 defines a position where the bending rigidity is minimized.
Japanese Patent Laid-Open No. 2003-168771 JP 2005-34550 A

  Even according to the above prior art inventions, the flight distance, hitting ball directivity and the like were insufficient. The present inventor has discovered a new technical problem that the prior art has potentially. The present invention solves this new technical problem by a technical idea that is completely different from the above-described prior art. According to the present invention, a shaft capable of improving the flight distance and the hitting ball directivity can be provided. Unlike the prior art described above, the present invention has been made in consideration of the shaft behavior during a swing in detail. According to the present invention, new functions and effects that have not been conceived in the past can occur.

Japanese Patent Application No. 2006-177457 defines the value of (b1-bmin) as in the present invention. In Japanese Patent Application No. 2006-177457, (b1-bmin) is set to be 24 (N · m ² ) or more and 35 (N · m ² ) or less. When (b1-bmin) is greater than 35 (N · m ² ), the shaft strength may be insufficient. In the present invention, a woven fabric in which carbon fibers are oriented in the shaft axis direction and the direction perpendicular thereto is used. With this configuration, the shaft of the present invention can maintain strength even when (b1-bmin) is increased, and can be a shaft excellent in feeling.

  The present invention can provide a golf club that is particularly suitable for less powerful golfers. The invention described in Japanese Patent Application No. 2006-177457 is particularly suitable for a golfer whose head speed with a driver is 40 to 45 m / s. On the other hand, since the (b1-bmin) is relatively large, the present invention is particularly suitable for a weak golfer whose head speed with a driver is about 30 to 35 m / s. For such a less powerful golfer, a shaft that is more easily formed than the shaft described in Japanese Patent Application No. 2006-177457 is suitable. According to the present invention, even a golfer with a slow head speed can obtain a satisfactory result.

  An object of the present invention is to provide a golf club shaft and a golf club excellent in flight distance performance and hitting directionality.

In the golf club shaft according to the present invention, the position 130 mm from the head side end of the shaft is the first position, the position 130 mm from the grip side end of the shaft is the tenth position, the first position and the tenth position. The positions that divide the position into nine equal parts are the second position, the third position,..., The eighth position, and the ninth position in order from the head side, and there are 10 positions from the first position to the tenth position. The measured bending rigidity EI is set to EI (1), EI (2),..., EI (9) and EI (10) in order from the head side, and the distance from the head end side of the measurement position ( mm) is the X-axis and the bending stiffness EI value (N · m ² ) is the Y-axis, and each of the points obtained by plotting the measured values at the 10 positions is T (1), T (2),..., T in order from the head side 9) and set to T (10), on the XY coordinate plane, the equation of the straight line K passing through the above T (10) and the T (1), is the [Y = aX + b1],
A value (N · m ² ) of a Y-intercept in a straight line parallel to the straight line K and passing through each of the points T (2), T (3), ..., T (8) and T (9) is When b2, b3,..., B8 and b9 are set, and the minimum value of the Y intercept values b2 to b9 is bmin,
The inclination “a” of the straight line K is 0.04 or more and 0.06 or less, which satisfies the following. B3, b4, b5, b6, b7 and b8 are all smaller than b1. The bmin is any one of b4, b5, b6 or b7. (B1-bmin) is 30 (N · ^{m 2)} or more 40 (N · ^{m 2)} or less. (B9-b1) is 4 or more and 15 (N · m ² ) or less. The shaft includes at least one woven fabric layer having carbon fiber warp and weft. One of the warp and the weft is substantially oriented in the shaft axial direction. The other of the warp and the weft is oriented in a direction substantially perpendicular to the shaft axial direction. Tensile strength of the carbon fiber constituting the woven fabric layer is 300 kgf / mm ² or more 680kgf / mm ² or less.

  Preferably, the fabric of the fabric layer is plain woven. In other words, the warp and the weft are plain woven.

Preferably, when the minimum value of EI (1) to EI (10) is E1, and the maximum value of EI (1) to EI (7) is E2, E1 is EI ( 2) EI (3), EI (4) or EI (5). Preferably, E1 is 12 (N · m ² ) or more and 20 (N · m ² ) or less. Preferably, the difference (E2-E1) is 30 (N · m ² ) or less. Preferably, the EI (10) is 60 (N · m ² ) or more and 90 (N · m ² ) or less.

  Preferably, the total shaft length is 43 inches or more. Preferably, the shaft weight is 30 g or more and 50 g or less.

  Preferably, the forward flex is 120 mm or more and 160 mm or less.

  In particular, for a less powerful golfer, the behavior of the shaft during swing is improved, and the golf club shaft is excellent in hitting directionality and flight distance performance.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  In addition, in this application, the tensile strength and tensile elasticity modulus of a fiber are the values measured based on JISR7601: 1986 "carbon fiber test method".

  FIG. 1 is an overall view of a golf club shaft 1 according to an embodiment of the present invention. The golf club shaft 1 is tubular. The shaft 1 is generally tapered as a whole. The shaft 1 has a head side end T and a grip side end B. The head side end T is an end on the small diameter side. The grip side end B is an end on the large diameter side. Although not shown, a golf club head is mounted near the head side end T, and a grip is mounted near the grip side end B. The shaft 1 is a carbon shaft. The carbon shaft is made of CFRP (carbon fiber reinforced resin).

  In the present invention, the bending stiffness EI at 10 positions is defined. The position in the present invention is a position in the shaft axial direction.

  Ten positions from the first position to the tenth position are defined as measurement positions of the bending rigidity EI. As shown in FIG. 1, the position 130 mm from the head side end T of the shaft 1 is the first position p1. A position 130 mm from the grip side end B of the shaft 1 is a tenth position p10. Positions that divide the first position p1 and the tenth position p10 into nine equal parts are the second position p2, the third position p3, the fourth position p4, the fifth position p5, and the sixth position p6 in order from the head side end T. The seventh position p7, the eighth position p8, and the ninth position p9.

The first position p1 to the tenth position p10 are arranged at equal intervals in the shaft axis direction. In FIG. 1, what is indicated by L1 is an interval between adjacent positions. When the total length of the shaft is L (mm), the interval L1 (mm) between adjacent positions is expressed by the following formula.
L1 = (L-260) / 9

  The bending stiffness EI measured at 10 positions from the first position p1 to the tenth position p10 is EI (1), EI (2),..., EI (9) and EI ( 10). That is, it is as follows.

The bending rigidity EI measured at the first position p1 is EI (1).
The bending stiffness EI measured at the second position p2 is EI (2).
The bending rigidity EI measured at the third position p3 is EI (3).
The bending rigidity EI measured at the fourth position p4 is EI (4).
The bending rigidity EI measured at the fifth position p5 is EI (5).
-The bending stiffness EI measured at the sixth position p6 is EI (6).
-The bending stiffness EI measured at the seventh position p7 is EI (7).
-The bending stiffness EI measured at the eighth position p8 is EI (8).
The bending rigidity EI measured at the ninth position p9 is EI (9).
The bending stiffness EI measured at the tenth position p10 is EI (10).

Based on these measured values, a graph is created on the XY coordinate plane. An example of this graph is shown in FIG. In this XY coordinate plane, the distance (mm) from the head side end T of the measurement position is taken as the X axis. The value (N · m ² ) of the bending stiffness EI is taken as the Y axis. Each of the points obtained by plotting the measured values at the 10 positions on the XY coordinate plane is T (1), T (2),..., T (9 ) And T (10). That is, it is as follows.

The X coordinate of T (1) is 130, and the Y coordinate of T (1) is EI (1).
The X coordinate of T (2) is (L1 × 1 + 130), and the Y coordinate of T (2) is EI (2).
The X coordinate of T (3) is (L1 × 2 + 130), and the Y coordinate of T (3) is EI (3).
The X coordinate of T (4) is (L1 × 3 + 130), and the Y coordinate of T (4) is EI (4).
The X coordinate of T (5) is (L1 × 4 + 130), and the Y coordinate of T (5) is EI (5).
The X coordinate of T (6) is (L1 × 5 + 130), and the Y coordinate of T (6) is EI (6).
The X coordinate of T (7) is (L1 × 6 + 130), and the Y coordinate of T (7) is EI (7).
The X coordinate of T (8) is (L1 × 7 + 130), and the Y coordinate of T (8) is EI (8).
The X coordinate of T (9) is (L1 × 8 + 130), and the Y coordinate of T (9) is EI (9).
The X coordinate of T (10) is (L1 × 9 + 130), and the Y coordinate of T (10) is EI (10).

On the XY coordinate plane, the equation of the straight line K passing through T (1) and T (10) is [Y = aX + b1]. That is, the slope of the straight line K is “a”, and the Y intercept (N · m ² ) of the straight line K is b1.

  The values of the Y intercepts on the straight lines parallel to the straight line K and passing through the points T (2), T (3),..., T (8) and T (9) are b2, b3,. .., b8 and b9. That is, it is as follows.

T2 is a point on the straight line [Y = aX + b2].
T3 is a point on the straight line [Y = aX + b3].
T4 is a point on the straight line [Y = aX + b4].
T5 is a point on the straight line [Y = aX + b5].
T6 is a point on the straight line [Y = aX + b6].
T7 is a point on the straight line [Y = aX + b7].
T8 is a point on the straight line [Y = aX + b8].
T9 is a point on the straight line [Y = aX + b9].

  FIG. 2 is an example of a graph in which measured values at 10 locations are plotted. The solid line in FIG. 2 indicates the straight line K. The broken line in FIG. 2 indicates a straight line [Y = aX + b8] passing through T8 as an example of a straight line passing through each of T2 to T9. FIG. 2 is a graph of Example 1 described later.

  The minimum value of the Y intercept values b2 to b9 is defined as bmin. That is, the minimum value among b2, b3, b4, b5, b6, b7, b8 and b9 is bmin.

In the shaft 1 defined as described above, the slope “a” of the straight line K is preferably 0.04 or more, and more preferably 0.05 or more. The slope “a” of the straight line K is preferably 0.06 or less. All of b3, b4, b5, b6, b7 and b8 are preferably smaller than b1. The bmin is preferably any of b4, b5, b6 or b7. (B1-bmin) is preferably 30 (N · m ² ) or more and 40 (N · m ² ) or less. (B9-b1) is preferably 4 (N · m ² ) or more and 15 (N · m ² ) or less.

  Next, the operational effects of the shaft 1 and the shaft behavior that is the premise thereof will be described.

  In a golf club, a head is mounted on the head side end T of the shaft. This head has a relatively large mass. Due to the inertia of the head and the like, the shaft behavior during the swing is as follows.

  When the swing starts, that is, when the swing-up (takeback) starts, the shaft is delayed in the head side. As a result of this reaction, at the end of the swing-up, the head side of the shaft precedes the swing-up direction. This bend is further increased at the start of the downswing. That is, at the start of the downswing, the head side of the shaft is delayed with respect to the downswing direction. Due to this natural reaction, the shaft tends to lead the head side in the swing direction from the start of the downswing to the impact. The behavior of the shaft affects the head speed during impact. The shaft flexure returns from a state where the head side is delayed to a state where the head side is not delayed, so that the head speed at the time of impact can be accelerated.

  Thus, the head speed Si at the time of impact is the sum of the swing speed S1 of the entire shaft and the head speed S2 resulting from the bending. That is, the relationship [Si = S1 + S2] is established. The swing speed S1 is a head speed resulting from movement of the entire shaft.

  The head speed S2 can change depending on the state of the shaft at the time of impact. The head speed S2 can vary depending on the timing of the bending behavior of the shaft and the impact. When the timing between the shaft behavior and the impact is bad, the head speed S2 may be negative. The head can be accelerated or decelerated by the return. If an impact is reached in a state where the head side is delayed, the acceleration due to the bending is not sufficient, and the head speed S2 becomes small. The head speed S2 can be maximized when the impact is reached at the moment when the bending in the direction in which the head side is delayed returns. In other words, the head speed S2 can be maximized by the fact that the bend in the direction of delaying the head side is almost coincident with the moment when the return shaft becomes almost straight and the moment of impact. By maximizing the head speed S2, the head speed Si at the time of impact can be maximized.

  In order to increase the head speed S2 due to the bending of the shaft, it is necessary to increase the bending of the shaft during the swing. In order to increase the bending of the shaft during the swing, it is preferable to decrease the bending rigidity EI of the intermediate portion of the shaft. However, simply reducing the bending rigidity EI of the shaft intermediate portion tends to have an impact with the shaft being delayed toward the head side. This tendency is particularly noticeable for beginner golfers. In order to improve this tendency, it is effective to increase the bending rigidity EI on the grip side of the shaft. That is, by reducing the bending rigidity EI at the intermediate portion and increasing the bending rigidity EI on the grip side, the bending in the direction in which the head is delayed increases, and the moment when this bending almost disappears can be an impact. .

  The bending of the shaft at the time of impact also affects the directionality of the hit ball. This is because the orientation of the face at the time of impact can change due to the bending of the shaft at the time of impact. For example, when the head is bent in the delayed direction, the face is easily opened. Due to the open face, the hit ball is likely to be sliced. On the contrary, the bending in the direction in which the head side precedes makes the face easy to close. The closed face makes it easier for the hit ball to become a hook. The impact in a state where the bending of the shaft is almost eliminated can improve the directionality of the hit ball.

  The bending of the shaft during impact also affects the launch angle. The bending in the direction in which the head side is delayed can reduce the loft angle at the time of impact. If the loft angle at impact is small, the launch angle is small and the trajectory is low. The impact when the shaft bending is almost eliminated can increase the loft angle at the time of impact compared to the impact when the head side is delayed. Increasing the loft angle at impact increases the launch angle. Increasing the launch angle can contribute to an increase in flight distance.

  From the viewpoint of increasing the head speed S2 by increasing the bending of the shaft at the start of the downswing, as described above, it is preferable that all of b3, b4, b5, b6, b7, and b8 are smaller than b1. . From the viewpoint of increasing the head speed S2 by increasing the bending of the shaft at the start of the downswing, the bmin is preferably any of b4, b5, b6 or b7, and the bmin is b5 or b6. More preferably.

  From the viewpoint of improving the hit feeling and hitting timing while softening the central portion of the shaft, it is necessary to make the rear end portion of the shaft harder than the front end portion of the shaft. From the viewpoint of improving the hit feeling and hitting timing, the slope “a” of the straight line K is preferably 0.04 or more, and more preferably 0.05 or more. From the viewpoint of suppressing the feeling of hitting ball from becoming excessively hard, the slope “a” of the straight line K is preferably 0.06 or less.

  Particularly for a less powerful golfer, the shaft weight is preferably 30 g or more and 50 g or less. If the shaft is too light, it will be difficult to take the swing timing, and it will be difficult to hit the ball at the sweet spot of the head. In this respect, the shaft weight is preferably 30 g or more, and more preferably 32 g or more. The shaft weight is preferably 50 g or less from the viewpoint of easily increasing the head speed even with a less powerful golfer.

In the case of using a less powerful golfer, from the viewpoint of increasing the head speed S2 by increasing the bending of the shaft at the start of the downswing, (b1-bmin) is preferably 30 (N · m ² ) or more, 31 (N · m ² ) or more is more preferable, and 32 (N · m ² ) is particularly preferable. In the case of using a less powerful golfer, from the viewpoint of suppressing the impact of the shaft without returning completely, (b1-bmin) is preferably 40 (N · m ² ) or less, and more preferably 39 or less. , 38 (N · m ² ) or less is particularly preferable.

The value of (b9-b1) is related to the ease of return of the bent shaft. Especially for a less powerful golfer, it is effective to increase the head speed with a flexible return shaft. As the value of (b9-b1) is larger, the bending tends to return. From the viewpoint of facilitating the return of bending in a less powerful golfer, (b9-b1) is preferably 4 (N · m ² ) or more, more preferably 5 (N · m ² ) or more, and 6 (N · m ² ). The above is particularly preferable. If the flexure returns too much, an impact is likely to occur in the state where the head precedes. (B9-b1) is preferably 15 (N · m ² ) or less, and 14 (N · m ² ) or less from the viewpoint of suppressing impact in a state where the head is advanced in a less powerful golfer and suppressing hook balls. Is more preferable, and it is preferably 13 (N · m ² ) or less.

  The shaft of the present invention has a fabric layer. The fabric layer includes a fabric. This fabric is made of carbon fiber. This fabric is produced by weaving carbon fiber bundles.

  The fabric layer may be formed by winding a prepreg. This prepreg is made by impregnating a fiber fabric with a resin. The fabric layer may be formed by winding only a fabric. The fabric layer may be formed by curing a prepreg, or may be composed of a fabric that is not impregnated with a resin. The textile layer of the Example mentioned later winds a prepreg.

  The woven fabric contained in the woven fabric layer is formed by weaving warps and wefts. The warp and the weft are substantially orthogonal. Warp and weft are carbon fiber bundles. For example, carbon fiber bundles such as 1K, 3K, 6K, 12K, 24K, and 48K are used as the warp and the weft. For example, 12K means that the number of filaments is 12,000. A widely used carbon fiber bundle of 12K is used.

  Examples of the weaving method include plain weave, twill weave and satin weave. In the manufacturing process of the shaft, there is a textile winding process. A plain weave fabric has a high weaving density, so that the fiber bundle is difficult to move in the winding process. Plain woven fabrics can suppress variations in shaft physical properties. From this viewpoint, the most preferable weaving method is plain weaving.

  One of the warp and the weft (for example, the warp) is substantially oriented in the shaft axis direction. It is difficult to make the fiber completely parallel to the shaft axis due to an error or the like that occurs when winding the taper surface. The angle formed by the orientation direction of one of the warp and weft (for example, warp) and the shaft axis is usually within ± 10 degrees.

  The other of the warp and the weft (for example, the weft) is oriented in a direction substantially perpendicular to the shaft axis direction. The fiber orientation angle may not be completely perpendicular to the shaft axis due to errors in manufacturing the shaft. The angle formed by the orientation direction of the other of the warp and the weft (for example, the weft) and the shaft axis is usually 85 degrees or more and 95 degrees or less.

Carbon fibers are preferred as the fibers constituting the fabric layer. The tensile strength of the carbon fiber constituting the fabric layer is not particularly limited. From the viewpoint of enhancing the strength against bending of the shaft, the tensile strength of the fiber constituting the fabric layer is preferably 300 kgf / mm ² or more, more preferably 350 kgf / mm ² or more, 400 kgf / mm ² or more is particularly preferable. Considering the physical properties of carbon fibers currently available, the tensile strength of the fiber constituting the fabric layer is preferably 680kgf / mm ² or less.

  Table 1 below shows the product number of the prepreg, the product number of the carbon fiber used in the prepreg, the tensile elastic modulus of the carbon fiber, the tensile strength of the carbon fiber, and the density of the carbon fiber. The prepregs shown in Table 1 are manufactured by Toray or Mitsubishi Rayon. As described in Table 1, TR1100M, TR1120M and TR3110M manufactured by Mitsubishi Rayon Co. can be used as the fabric layer. TR1100M, TR1120M and TR3110M manufactured by Mitsubishi Rayon Co., Ltd. are prepregs obtained by impregnating a plain weave fabric with a resin.

  The shaft of the present invention preferably has a straight layer. The straight layer increases the bending rigidity of the shaft. The straight layer facilitates the design of forward and reverse flexes. The straight layer increases the bending strength of the shaft. The straight layer is a layer made of a fiber reinforced resin, in which the fiber orientation angle is substantially parallel to the shaft axis. However, normally, the fiber orientation angle is not completely parallel to the shaft axis. Due to errors that occur when winding the prepreg around the tapered surface, it is difficult for all fibers to be perfectly parallel to the shaft axis. The angle formed by the orientation direction of the fibers constituting the straight layer and the shaft axis is usually within ± 10 degrees.

As the fiber constituting the straight layer, carbon fiber is preferable. From the viewpoint of increasing the strength against bending of the shaft (bending strength), the tensile strength of the fibers constituting the straight layer is preferably 500 kgf / mm ² or more. From the viewpoint of increasing the bending strength of the shaft, at least one high-strength straight layer having a tensile strength of 580 kgf / mm ² or more is preferably disposed. The high-strength straight layer is preferably provided over the entire length of the shaft. Tensile strength of the fibers constituting the high strength straight layer is more preferably 590kgf / mm ² or more, more preferably 600 kgf / mm ² or more, 630kgf / mm ² or more is particularly preferable. Considering the physical properties of available carbon fibers, the tensile strength of the fibers constituting the high-strength straight layer is preferably 680 kgf / mm ² or less.

  The shaft of the present invention may have a hoop layer. The hoop layer is a layer made of a fiber reinforced resin and has a fiber orientation angle substantially perpendicular to the shaft axis. As the hoop layer, for example, 805S-3 manufactured by Toray Industries, Inc. described in Table 1 below is used. This 805S-3 has a smaller weight per unit area, a carbon fiber weight per unit area, and a smaller thickness than other prepreg varieties. Such a thin prepreg is suitable for the hoop layer because it is easy to bend and wrap the carbon fiber.

  When this happens, a force in the direction of crushing acts on the shaft. The shaft is deformed by this force. This deformation is also referred to as crushing deformation below. Due to the crushing deformation, the cross section of the shaft becomes substantially elliptical. When the crushing deformation increases, the shaft may be crushed. The fabric layer has fibers oriented substantially perpendicular to the shaft axial direction. This fiber is wound substantially along the circumferential direction of the shaft. Hereinafter, this fiber is also referred to as a circumferential fiber. The circumferential fiber of the fabric layer makes it difficult for the shaft to be crushed and the strength of the shaft can be improved.

  The fabric layer has fibers that are substantially parallel to the axial direction of the shaft. Hereinafter, this fiber is also referred to as an axial fiber. This axial fiber increases the strength against bending deformation.

  As described above, in the present invention, (b1-bmin) is increased as compared with Japanese Patent Application No. 2006-177457 for the purpose of dealing with a less powerful golfer. If (b1-bmin) is increased, the strength may be insufficient. The present invention can overcome the lack of strength by providing a fabric layer.

  The influence of the circumferential fiber on the rigidity of the bending direction of the shaft is small. The influence on the stiffness in the bending direction by the circumferential fibers is smaller than that by the axial fibers. On the other hand, the influence of the circumferential fiber on the crushing deformation is great.

  When hitting, a particularly large impact force acts near the head. For the purpose of reinforcing the vicinity of the head, a general shaft is provided with a tip reinforcing layer that reinforces only the vicinity of the tip. Due to the presence of this front end reinforcing layer, the thickness of the shaft is generally thinner on the front end side than on the rear end side. Further, the shaft is usually provided with a taper. In the portion near the head side end T, the shaft is relatively thin. In the portion near the grip side end B, the shaft is relatively thick.

  The thinner the part, the easier it will be crushed. Also, the larger the shaft diameter, the more likely it will be crushed. The circumferential fiber effectively suppresses the shaft from being crushed. It is effective that the circumferential fiber is used in a portion that is easily crushed. From this point of view, the fabric layer is preferably provided at least on the rear end portion of the shaft. Specifically, the shaft longitudinal direction distance from the grip side end B is Lb, and when the fabric layer is disposed in a range from 0 mm to Pfmm, the position Pf is set to 50% or more of the total shaft length L. It is preferable. That is, the position Pf is preferably set to [L / 2] or more. More preferably, the position Pf is set to [2/3] or more of the entire shaft length L. From the viewpoint of enhancing the effect of the fabric layer, the fabric layer is particularly preferably provided over the entire length of the shaft.

  In Japanese Patent Application No. 2006-177457, the return of the bending of the shaft is optimal, and the head speed can be improved. However, if the head speed can be improved with respect to a less powerful golfer with a slower head speed, it is extremely preferable for a less powerful golfer. As described above, in order to improve the head speed against a less powerful golfer, (b1-bmin) may be increased. However, simply increasing (b1-bmin) tends to decrease the strength of the shaft. Therefore, in the present invention, a fabric layer is used.

  The axial fibers of the fabric layer can improve the strength of the shaft against bending forces. Moreover, the strength of the shaft can be improved by the circumferential fibers of the fabric layer. As described above, the circumferential fibers suppress the shaft from being crushed due to the bending of the shaft, so that the shaft strength can be increased.

  The circumferential fiber can speed up the flexure return without impairing the flexure size. The relationship between the bend and return of bend and the circumferential fiber will be further described. The circumferential fiber has a little influence on the bending rigidity of the shaft because the fiber orientation direction is substantially perpendicular to the longitudinal direction of the shaft. Therefore, the circumferential fiber does not substantially impair the bending of the shaft against a weak golfer. On the other hand, as described above, when the shaft is bent, it is crushed and deformed. In other words, the bending deformation and crushing deformation of the shaft are linked. Circumferential fibers increase the reaction force against crushing deformation. Circumferential fibers contribute to the early recovery of crushing deformation. Due to the early recovery from crushing deformation, the bending of the shaft also recovers early. That is, the circumferential fiber speeds up the return of the shaft. As described above, the shaft of the present invention does not lose its bending, and the return of the shaft is quick. Therefore, the shaft of the present invention is particularly suitable for a less powerful golfer.

  In the woven layer, axial fibers and circumferential fibers are woven together. By being woven, the circumferential fibers are reinforced by the axial fibers. By this reinforcement, the recovery effect of the crushing deformation of the circumferential fibers can be made larger than that of the hoop layer. Compared with the case where the straight layer and the hoop layer are used in combination, the fabric layer has a high effect of speeding up the return of bending. A plain weave fabric has a high weaving density, so that the reinforcing effect by the axial fibers is particularly high. Therefore, the plain weave fabric has a particularly high recovery effect of crushing deformation.

  SG type three-point bending strength is SG type breaking strength defined by the Product Safety Association. FIG. 3 shows a method for measuring SG type three-point bending strength. As shown in FIG. 3, while supporting the shaft 1 from below at two support points t1 and t2, a load F is applied from above to below at a load point t3. The position of the load point t3 is a position that bisects the support point t1 and the support point t2. Measurement is performed with the load point t3 coincident with the point to be measured.

  There are four measurement points in the SG type three-point bending strength, which are the T point, the A point, the B point, and the C point. The point T is a point 90 mm from the head side end T. A point is a point of 175 mm from the head side end T. Point B is a point 525 mm from the head side end T. The point C is a point 175 mm from the grip side end B. The value (peak value) of the load F when the shaft 1 is broken is the SG type three-point bending strength. When the T point is measured, the span S is 150 mm. When the points A, B, and C are measured, the span S is set to 300 mm.

  Various external forces can act on the shaft during normal use of the golf club other than during swinging. Examples of the external force that can be applied at times other than the swing include a force that acts on the shaft when the club is taken out from the caddy back, and a force that acts on the shaft when the club is accidentally stepped on. From the viewpoint of suppressing breakage due to these external forces, the B-point strength of the SG type three-point bending strength is preferably 60 kgf or more, more preferably 62 kgf or more, and particularly preferably 64 kgf or more. There is a correlation between the shaft strength and the rigidity, and the EI value tends to increase as the strength increases. From the viewpoint of suppressing the EI value from becoming excessively large and increasing the flexure, the point B strength is preferably 90 kgf or less.

  In the present application, the minimum value from EI (1) to EI (10) is E1, and the maximum value from EI (1) to EI (7) is E2. From the viewpoint of increasing the head speed S2 by softening the intermediate portion of the shaft, E1 is preferably EI (2), EI (3), EI (4) or EI (5).

In a less powerful golfer, E1 is preferably 12 (N · m ² ) or more from the viewpoint of suppressing an excessive bending at the start of a downswing and suppressing an impact in a state where the bending does not fully return. N · m ² ) or more is more preferable, and 14 (N · m ² ) or more is particularly preferable. From the viewpoint of increasing the head speed S2 by increasing the bending of the shaft at the start of the downswing, E1 is preferably 20 (N · m ² ) or less, more preferably 19 (N · m ² ) or less, and 18 (N -M ² ) or less is particularly preferred.

In a less powerful golfer, the lower limit of the difference (E2-E1) is 15 (N · m ² ) or more from the viewpoint of optimizing the timing of the bending behavior and impact of the shaft and optimizing the bending amount of the shaft. more preferably from 18 (N · ^{m 2)} or more, the upper limit is preferably 33 (N · ^{m 2)} or less of the difference (E2-E1), more preferably 30 (N · ^{m 2)} or less, 29 (N -M ² ) or less is particularly preferred.

From the standpoint of proper return and suppressing the impact when the head is delayed, EI (10) is preferably 60 (N · m ² ) or more. EI (10) is preferably 90 (N · m ² ) or less from the viewpoint of suppressing the impact in the state where the head precedes and suppressing the hook ball.

  The present invention relates to shaft flexing and flexing return. The longer the overall length L of the shaft, the greater the influence of bending. The longer the overall length L of the shaft, the more easily the effect of the present invention becomes apparent. From this viewpoint, the total shaft length L is preferably 41 inches (1041 mm) or more, more preferably 43 inches (1092 mm) or more, and more preferably 44 inches (1117 mm) or more. It is particularly preferable that the thickness be 45 inches (1143 mm) or more. From the viewpoint of securing the strength of the shaft, the total shaft length L is preferably 52 inches (1321 mm) or less, more preferably 50 inches (1270 mm) or less, and particularly preferably 48 inches (1219 mm) or less.

  When a less powerful golfer is used, the forward flex f of the shaft is preferably 120 mm or more and 121 mm or more from the viewpoint of suppressing the feeling that is too hard and increasing the head speed S2 due to the bending of the shaft. More preferably, 122 mm or more is particularly preferable. When a less powerful golfer is used, the forward flex f is preferably equal to or less than 160 mm, more preferably equal to or less than 159 mm, from the viewpoint of suppressing an excessively soft feeling and suppressing an impact when the head side is delayed. The following are particularly preferred:

  The shaft manufacturing method according to the present invention is preferably a sheet winding method. As the matrix resin of the prepreg, a thermosetting resin or a thermoplastic resin other than the epoxy resin can be used in addition to the epoxy resin.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

  The measuring method is as follows.

[Measurement method of bending stiffness EI]
FIG. 4 is a diagram for explaining a method of measuring the bending rigidity EI. The bending stiffness EI was measured using an Intesco 2020 model (maximum load 500 kg). As shown in FIG. 4, while supporting the shaft 1 from below at the two support points 3 and 5, the deflection amount α when the load F was applied to the measurement point P from above was measured. The measurement point P is any one of p1 to p10 described above. The distance (span) between the support point 3 and the support point 5 was 200 mm. The measurement point P was a position that divides the support point 3 and the support point 5 into two equal parts. The tip of the indenter 7 to which the load F is applied from above is rounded. The cross-sectional shape of the tip of the indenter 7 has a curvature radius of 10 mm in a cross section parallel to the shaft axial direction. In the cross section perpendicular to the shaft axis direction, the cross-sectional shape of the tip of the indenter 7 is a straight line, and the length of this straight line is 45 mm.

  The support 9 supports the shaft 1 from below at the support point 3. The tip of the support 9 has a convex roundness. The cross-sectional shape of the tip of the support 9 has a radius of curvature of 15 mm in a cross section parallel to the shaft axial direction. In the cross section perpendicular to the shaft axis direction, the cross-sectional shape of the tip of the support 9 is a straight line, and the length of this straight line is 50 mm. The shape of the support 11 is the same as that of the support 9. The support 11 supports the shaft 1 from below at the support point 5. The tip of the support 11 has a convex roundness. The cross-sectional shape of the tip of the support 11 has a radius of curvature of 15 mm in a cross section parallel to the shaft axial direction. In the cross section perpendicular to the shaft axis direction, the cross-sectional shape of the tip of the support 11 is a straight line, and the length of this straight line is 50 mm.

The indenter 7 was moved downward at a speed of 5 mm / min while fixing the support 9 and the support 11. The movement of the indenter 7 was completed when the load F reached 20 kg. The deflection amount α (mm) of the shaft 1 at the moment when the movement of the indenter 7 was completed was measured. The bending stiffness EI (N · m ² ) was calculated by the following formula.
EI (N · m ² ) = 32.7 / α

[Measurement of forward flex f]
FIG. 5A is a diagram for explaining a method of measuring the forward flex f. As shown in FIG. 5, the first support point 13 was set at a position 75 mm from the grip side end B. Further, a second support point 15 was set at a position 215 mm from the grip side end B. The first support point 13 is provided with a support 17 that supports the shaft 1 from above. The second support point 15 is provided with a support 19 that supports the shaft 1 from below. In a state where there was no load, the shaft axis of the shaft 1 was substantially horizontal. A load of 2.7 kg was applied to the load point m, which is 1039 mm from the grip side end B, vertically downward. The moving distance (mm) of the load point m from the state without load to the state with load applied was defined as the forward flex f. This movement distance is a movement distance along the vertical direction.

  In addition, the cross-sectional shape of the part (henceforth a contact part) contact | abutted with the shaft of the support body 17 is as follows. In the cross section parallel to the shaft axis direction, the cross-sectional shape of the contact portion of the support 17 has a convex roundness. The radius of curvature of this roundness is 15 mm. In the cross section perpendicular to the shaft axis direction, the cross-sectional shape of the contact portion of the support 17 has a concave roundness. The radius of curvature of the concave roundness is 40 mm. In the cross section perpendicular to the shaft axis direction, the horizontal length (length in the depth direction in FIG. 5) of the contact portion of the support 17 is 15 mm. The cross-sectional shape of the contact portion of the support 19 is the same as that of the support 17. The cross-sectional shape of the contact portion of a load indenter (not shown) that applies a load of 2.7 kg at the point m has a convex roundness in a cross section parallel to the shaft axial direction. The radius of curvature of this roundness is 10 mm. The cross-sectional shape of the contact portion of a load indenter (not shown) that applies a load of 2.7 kg at the point m is a straight line in a cross section perpendicular to the shaft axial direction. The length of this straight line is 18 mm. In this way, the forward flex f was measured.

[Measurement of reverse flex]
The first support point 13 is at a position 12 mm from the head side end T, the second support point 15 is at a position 152 mm from the head side end T, the load point m is 932 mm from the head side end T, and the load is 1 Measured in the same manner as the forward flex f except that it was 3 kg. This inverse flex measurement method is shown in FIG.

[Example 1]
A shaft was produced by a sheet winding method. A plurality of prepregs were wound around a metal mandrel and laminated. A developed view of the laminated prepreg is shown in FIG. Nine prepregs were wound around a mandrel (not shown) in the order of prepreg s1, prepreg s2, ..., prepreg s9. In FIG. 6, the prepreg shown on the upper side is laminated on the inner side.

  The prepreg s1 is a layer that reinforces the tip. In the prepreg s1, the fiber orientation angle is substantially parallel (0 degree) to the shaft axis. That is, the prepreg s1 constitutes a straight layer. The prepreg s2 is provided over the entire length of the shaft. The prepreg s2 is a so-called bias layer. In the prepreg s2, the fiber orientation angle is substantially −45 degrees with respect to the shaft axis. The prepreg s3 is also provided over the entire length of the shaft. The prepreg s3 is a so-called bias layer. In the prepreg s3, the fiber orientation angle is substantially +45 degrees with respect to the shaft axis. The prepreg s3 and the prepreg s4 are overlapped with each other and wound in this state. When the prepreg s3 and the prepreg s4 are overlapped, the prepreg s3 is reversed from the state of FIG. By this turning over, the fiber orientation angle of the prepreg s2 and that of the prepreg s3 are opposite to each other.

  The prepreg s4 is a reinforcing layer that reinforces the tip. In the prepreg s4, the fiber orientation angle is substantially parallel to the shaft axis. That is, the prepreg s4 constitutes a straight layer. The prepreg s5 is a layer that reinforces the rear end. In the prepreg s5, the fiber orientation angle is substantially parallel to the shaft axis. That is, the prepreg s5 constitutes a straight layer. The prepreg s6 is provided over the entire length of the shaft. The prepreg s6 is a high-strength straight layer. In the prepreg s6, the fiber orientation angle is substantially parallel to the shaft axis. That is, the prepreg s6 constitutes a straight layer.

  The prepreg s7 is a woven prepreg. The prepreg s7 includes a plain weave fabric. The prepreg s7 is provided over the entire length of the shaft. The prepreg s7 has warps and wefts. One of the warp and the weft is substantially oriented in the shaft axial direction. One of the warp and the weft is an axial fiber. The other of the warp and the weft is oriented in a direction substantially perpendicular to the shaft axial direction. The other of the warp and the weft is a circumferential fiber.

  The prepreg s8 is provided over the entire length of the shaft. In the prepreg s8, the fiber orientation angle is substantially parallel to the shaft axis. That is, the prepreg s8 constitutes a straight layer. The prepreg s8 is a high-strength straight layer. The prepreg s9 is a reinforcing layer that reinforces the tip. In the prepreg s9, the fiber orientation angle is substantially parallel to the shaft axis. That is, the prepreg s9 constitutes a straight layer. The dimensions of the prepregs s1 to s9 are as shown in FIG. The unit of this dimension is mm.

The prepreg varieties (product names) used from prepreg s1 to prepreg s9 and the elastic modulus of the carbon fiber are shown in Table 2 below. The varieties shown in Table 2 are prepregs manufactured by Toray or Mitsubishi Rayon. A hyphen and a numerical value are added to the end of the product name of the prepreg made by Toray. These "-7" etc. have shown the fiber weight per 1 m < ² > in a prepreg. Specifically, “−7” indicates that the fiber weight per 1 m ² is 75 g. “−3” indicates that the fiber weight per 1 m ² is 30 g. “−10” and “−11” indicate that the fiber weight per 1 m ² is 100 g, “−12” indicates that the fiber weight per 1 m ² is 125 g, and “−15” indicates It shows that the fiber weight per 1 m ² is 150 g. For example, “3255G-12” has a tensile elastic modulus of carbon fiber used of about 24 t / mm ² and a fiber weight per 1 m ² of 125 g. In all varieties shown in Table 2, the matrix resin is an epoxy resin.

  Of the prepregs s1 to s9, the fabric layer is the prepreg s7. The prepreg s7 is provided over the entire length of the shaft. By providing the straight layer s8 outside the fabric layer s7, the fabric layer s7 is not polished in the shaft surface polishing step. On the other hand, the fabric layer s7 is provided adjacent to the outermost layer, so that the fabric layer s7 is located on the outer layer side. By providing the woven fabric layer s7 on the outer layer side, the diameter of the woven fabric layer is increased and the crushing suppression effect is enhanced.

  A polypropylene tape was wound around the outside of the prepregs s1 to s9 laminated in this way. This was molded while being cured by heating and pressing in an oven. The mandrel was extracted from the molded body taken out from the oven. Both ends were cut in order to align the length, surface polishing was performed, and the shaft according to Example 1 was obtained. A head and a grip were attached to this shaft, and a golf club according to the shaft 1 was obtained. As the head, “SRIXON W-505 Loft 10.5 degrees” manufactured by SRI Sports Co., Ltd. was used.

[Example 2]
A shaft and a golf club according to Example 2 were obtained in the same manner as in Example 1 except that the types and configurations of the prepregs s1 to s9 were as shown in Table 2.

In TR3110M used in Example 2, the type name of warp and weft is [TR30S 3L]. This 3L means a carbon fiber bundle having 3000 filaments. The density of TR3110M (number of carbon fiber bundles / 25 mm) is 12.5 for the warp and 12.5 for the weft. The weight of TR3110M is 200 (g / m ² ), and the thickness is 0.23 mm.

In TR1100M used in Example 1, the warp and weft types are [TR40 1L]. 1 L means that the number of filaments is a carbon fiber bundle of 1000. The density of TR1100M (number of carbon fiber bundles / 25 mm) is 17.5 for warp and 17.5 for weft. Weight of TR1100M is 95 (g / ^{m 2),} thickness of 0.12 mm.

[Comparative Examples 1 to 6]
The shafts and golf clubs according to Comparative Examples 1 to 6 were obtained in the same manner as in Example 1 except that the types and configurations of the prepregs s1 to s9 were as shown in Table 2. In Comparative Example 1, the prepreg s5, the prepreg s7, and the prepreg s8 were not used. In Comparative Example 2, the prepreg s4 and the prepreg s5 were not used. Comparative Example 5 is the same as Example 1 except that the prepreg s7 is a hoop layer. Comparative Example 6 is the same as Example 1 except that prepreg s7 was not used.

  The specifications and evaluation results of Examples and Comparative Examples are shown in Tables 3 to 5 below. The method for measuring the bending stiffness EI is as described above.

  FIG. 7 is a line graph in which T1 to T10 are plotted and connected by a straight line in each of Examples 1 and 2 and Comparative Examples 1 to 6.

  The evaluation result by actual hitting will be described. As Table 3 shows, the items of evaluation by actual hitting are four items of [head speed], [launch angle], [flying distance], and [feeling].

Twenty testers hit 10 golf balls at each golf club, and by averaging all these data, [head speed], [launch angle], [flying distance] and [feeling] data were obtained. Obtained. The handicap of 20 testers is 20 or more and 35 or less. These data are shown in Table 2 below. As the golf ball, “HI-BRID Everio” (registered trademark) manufactured by SRI Sports, which is a commercially available three-piece ball, was used. [Flying distance] is a distance in a direction connecting the hit ball position and the target position. Each tester gave an evaluation score according to the following criteria, and an average value of evaluation scores of 10 golfers was set as an evaluation value of [feeling]. The closer the evaluation value is to 3, the better the result.
・ The shaft feels very hard ・ ・ ・ 1 point ・ The shaft feels a little hard.・ ・ ・ Two points ・ The shaft hardness is just right.・ ・ ・ 3 points ・ The shaft feels a little soft.・ ・ ・ 4 points ・ The shaft feels very soft. ... 5 points

  As shown in the table, the example has a higher evaluation than the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The present invention can be applied to all types of golf clubs, such as wood type golf clubs and iron type golf clubs, and their shafts.

FIG. 1 is a diagram for explaining a position where a bending rigidity EI is measured in a shaft according to the present invention. FIG. 2 is an example of a graph in which measured values of bending stiffness EI at 10 locations are plotted on an XY coordinate plane. FIG. 3 is a diagram for explaining a method of measuring the SG type three-point bending strength. FIG. 4 is a diagram for explaining a method of measuring the bending rigidity EI. FIG. 5A is a diagram for explaining a method of measuring the forward flex f. FIG.5 (b) is a figure which shows the measuring method of a reverse type flex. FIG. 6 is a development view of the prepreg on the shaft of the embodiment or the like. FIG. 7 is a graph of Examples 1 and 2 and Comparative Examples 1 to 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shaft T ... Head side end B ... Grip side end p1 ... 1st position p2 ... 2nd position p3 ... 3rd position p4 ... 4th position p5 ... 5th position p6 ... 6th position p7 ... 7th position p8 ... 8th position p9 ... 9th position p10 ... 10th position L ... Total shaft length

Claims (6)

The position 130 mm from the head side end of the shaft is the first position, the position 130 mm from the grip side end of the shaft is the tenth position, and the position that divides the first position and the tenth position into nine equal parts Are the second position, the third position, ..., the eighth position and the ninth position in order from the head side,
The bending stiffness EI measured at 10 positions from the first position to the tenth position is EI (1), EI (2),..., EI (9) and EI (10) in order from the head side. And
The measured values at the above 10 positions are plotted on the XY coordinate plane in which the distance (mm) from the head end side of the measurement position is the X axis and the bending rigidity EI value (N · m ² ) is the Y axis. , T (1), T (2),..., T (9) and T (10) in order from the head side.
On the XY coordinate plane, the equation of the straight line K passing through T (1) and T (10) is [Y = aX + b1],
A value (N · m ² ) of a Y-intercept in a straight line parallel to the straight line K and passing through each of the points T (2), T (3), ..., T (8) and T (9) is B2, b3,..., B8 and b9, respectively.
When the minimum value of the Y intercept values b2 to b9 is bmin,
The slope “a” of the straight line K is 0.04 or more and 0.06 or less,
B3, b4, b5, b6, b7 and b8 are all smaller than b1,
The bmin is any one of b4, b5, b6 or b7,
(B1-bmin) is 30 (N · m ² ) or more and 40 (N · m ² ) or less,
(B9-b1) is 4 or more and 15 (N · m ² ) or less,
Comprising at least one woven fabric layer having carbon fiber warp and weft,
One of the warp and the weft is substantially oriented in the shaft axial direction,
The other of the warp and the weft is oriented in a direction substantially perpendicular to the shaft axial direction,
A shaft for a golf club, wherein the carbon fiber constituting the woven fabric layer has a tensile strength of 300 kgf / mm ^{2 to} 680 kgf / mm ² .   The golf club shaft according to claim 1, wherein the fabric of the fabric layer is plain woven. The minimum value from EI (1) to EI (10) is E1,
When the maximum value from EI (1) to EI (7) is E2,
E1 is EI (2), EI (3), EI (4) or EI (5);
E1 is 12 (N · m ² ) or more and 20 (N · m ² ) or less,
The difference (E2-E1) is 30 (N · m ² ) or less,
^2. The golf club shaft according to claim 1, wherein the EI (10) is 60 (N · m ² ) or more and 90 (N · m ² ) or less.   2. The golf club shaft according to claim 1, wherein the shaft has a total length of 43 inches or more and a shaft weight of 30 g or more and 50 g or less.   2. The golf club shaft according to claim 1, wherein the forward flex is 120 mm or more and 160 mm or less. It has a head, a shaft, and a grip.
This shaft
The position 130 mm from the head side end of the shaft is the first position, the position 130 mm from the grip side end of the shaft is the tenth position, and the position that divides the first position and the tenth position into nine equal parts Are the second position, the third position, ..., the eighth position and the ninth position in order from the head side,
The bending stiffness EI measured at 10 positions from the first position to the tenth position is EI (1), EI (2),..., EI (9) and EI (10) in order from the head side. And
The measured values at the above 10 positions are plotted on the XY coordinate plane in which the distance (mm) from the head end side of the measurement position is the X axis and the bending rigidity EI value (N · m ² ) is the Y axis. , T (1), T (2),..., T (9) and T (10) in order from the head side.
On the XY coordinate plane, the equation of the straight line K passing through T (1) and T (10) is [Y = aX + b1],
A value (N · m ² ) of a Y-intercept in a straight line parallel to the straight line K and passing through each of the points T (2), T (3), ..., T (8) and T (9) is B2, b3,..., B8 and b9, respectively.
When the minimum value of the Y intercept values b2 to b9 is bmin,
The slope “a” of the straight line K is 0.04 or more and 0.06 or less,
B3, b4, b5, b6, b7 and b8 are all smaller than b1,
The bmin is any one of b4, b5, b6 or b7,
(B1-bmin) is 30 (N · m ² ) or more and 40 (N · m ² ) or less,
(B9-b1) is 4 or more and 15 (N · m ² ) or less,
Comprising at least one woven fabric layer having carbon fiber warp and weft,
One of the warp and the weft is substantially oriented in the longitudinal direction of the shaft,
The other of the warp and the weft is oriented in a direction substantially perpendicular to the longitudinal direction of the shaft,
A golf club in which a tensile strength of carbon fibers constituting the fabric layer is 300 kgf / mm ² or more and 680 kgf / mm ² or less.

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