JPWO2005065785A1 - Golf shaft - Google Patents

Abstract

Provided is a golf shaft made of fiber reinforced resin formed by laminating a plurality of fiber reinforced resin layers. The fiber reinforced resin layer includes a 4-axis fabric layer obtained by reinforcing a 4-axis fabric with a molding resin. A four-axis fabric is a plurality of longitudinal yarns extending in parallel with the longitudinal direction of the shaft, a plurality of transverse shaft yarns extending along a direction orthogonal to the longitudinal direction of the shaft, and a diagonally crossing left and right with respect to the longitudinal direction of the shaft. It consists of a set of a plurality of oblique shaft yarns. At least one type of axial yarn among the vertical axis yarn, the horizontal axis yarn, and the oblique axis yarn is formed of reinforcing fibers having characteristics different from those of the other axis yarns.

Description

  The present invention relates to a golf shaft having good vibration characteristics and improved ease of timing.

  The timing of the swing of the golf club differs depending on the characteristics, weight, length, center of gravity, hardness, etc. of the player and the golf shaft. In order to facilitate this timing, various improvements have been made to the golf shaft. A shaft flex design item related to timing is shaft flex. It is known that this shaft flex is managed by a bending amount or a natural frequency when a golf shaft is fixed in the vicinity of the grip and a certain weight is added to the tip of the golf shaft.

  The amount of bending of the shaft during the swing is a combination of deformation due to bending in the direction along the axis of the golf shaft and deformation due to compression along the radial direction perpendicular to the axis. Therefore, if the deformation due to compression is large, the deformation due to bending is obstructed, and it becomes difficult for the golfer to feel a distorted feeling, and the restoring force of the golf shaft is also reduced, resulting in a problem that the flight distance is lost.

  Therefore, when selecting a flex that is easy for a golfer to take timing, it is necessary to consider the radial rigidity of the golf shaft. In order to satisfy the requirements for deformation due to bending and radial deformation at the same time, a multilayer material in which thin prepregs are laminated in multiple layers is adopted as the material of the shaft, or a multi-axial woven fabric is adopted. It is known to do.

  Regarding golf shafts made of fiber reinforced resin, with respect to fabrics, particularly shafts using multiaxial fabrics mainly composed of three axes, JP-A-58-76559, JP-A-3-151989, and JP-A-4 -51970. In the golf shafts described in these documents, a multiaxial fabric is used for the purpose of reinforcing the structure or improving the productivity by utilizing the characteristics of the triaxial fabric.

  Also, Hiroshi Fukuda, “Design of Composite Materials”, Journal of the Textile Machinery Society, Japan Textile Machinery Society, November 25, 1994, Volume 47, No. 11, p. According to 467-472, the 4-axis woven fabric has an effect as a pseudo-isotropic material, and there is a description that “the same characteristics are exhibited even if a load acts from any direction”, and the advantages as a structure are discussed. It has been.

  Furthermore, Japanese Patent Application Laid-Open No. 2000-245880 describes a golf shaft using a four-axis fabric. This golf shaft is superior in bending, twisting, and compression rigidity by using a 4-axis woven fabric. It is strong enough to be applied in all directions, has high reactivity, and has a good balance of restoring force. It is said that a golf shaft can be obtained.

  A golf shaft using a multi-axial woven fabric such as the triaxial woven fabric or the 4-axial woven fabric utilizes pseudo-isotropic property or the like that is a characteristic of a structure. When a load is applied to the golf shaft, different stresses are applied to the longitudinal direction of the shaft, that is, the longitudinal direction, the transverse direction perpendicular to the longitudinal direction, and the oblique direction having a predetermined angle with respect to the longitudinal direction. In order to cope with these, different characteristics are required in each direction. However, the above-mentioned documents do not disclose any such problems.

  In addition, when specifying the performance of the golf shaft, in addition to the mechanical characteristics, sensory expressions such as “play” and “stick” are used. Such a sensory expression is often used by golfers, particularly advanced players, but has not yet been specified as a physical quantity. Thus, the current situation is that the means for devising a “playing” shaft is not clear.

  Accordingly, an object of the present invention is to provide a golf shaft that has excellent mechanical characteristics and that can satisfy the demands regarding characteristics and a sense of stability based on sensory expressions such as “playing”. It is.

  The present invention has been made to achieve the above object, and the golf shaft of one embodiment of the present invention is made of a fiber reinforced resin formed by laminating a plurality of fiber reinforced resin layers. The fiber reinforced resin layer includes a four-axis fabric layer obtained by reinforcing a four-axis fabric with a molding resin, and the four-axis fabric has a plurality of longitudinal yarns extending in parallel to the longitudinal direction of the shaft in a direction orthogonal to the longitudinal direction of the shaft. A plurality of transverse axis yarns extending along the shaft and a set of a plurality of oblique axis yarns obliquely laterally with respect to the longitudinal direction of the shaft. At least one type of axial yarn among the vertical axis yarn, the horizontal axis yarn, and the oblique axis yarn is formed of reinforcing fibers having characteristics different from those of the other axis yarns.

  The reinforcing fiber of the vertical axis yarn is made of carbon fiber having a tensile strength of 4000 MPa to 7000 MPa, and the reinforcing fiber of the horizontal axis yarn is made of carbon fiber having a tensile elastic modulus of 240 GPa to 800 GPa. The fiber is preferably made of carbon fiber having a tensile modulus of 400 GPa to 800 GPa.

The fineness of the reinforcing fibers of the four-axis fabric layer is preferably 50 tex to 200 tex (g / 1000 m).
The four-axis fabric layer is preferably disposed on the outermost layer or on the second layer from the outermost layer.
The resin content of the fiber reinforced resin layer of the golf shaft is preferably 20% to 30% of the total weight of the golf shaft.

The golf shaft may have a tapered shape in which the outer diameter gradually increases from the front end toward the rear end.
A golf club can be configured by mounting a head on the front end of any of the above-mentioned preferred golf shafts and mounting a grip on the rear end.

The front view which shows the golf shaft of one Embodiment of this invention. The figure for demonstrating the fiber reinforced resin prepreg used for the golf shaft of FIG. The figure which shows the structure of a 4-axis fabric. The perspective view for demonstrating the measuring method of the vibration damping characteristic of a shaft. The figure for demonstrating the measuring method of EI value of a shaft.

Hereinafter, an embodiment embodying the present invention will be described in detail.
FIG. 1 shows a golf shaft according to an embodiment of the present invention. The golf shaft 1 is formed by laminating a plurality of fiber reinforced resin layers and has a total length of 1143 mm. The golf shaft 1 has a taper shape in which the outer diameter gradually increases from the front end toward the rear end, and a head 2 is attached to the front end on the small diameter side, and a grip 3 is provided on the rear end on the large diameter side. Is installed.

  The fiber reinforced resin layer is formed using a plurality of fiber reinforced resin prepregs. These fiber reinforced resin prepregs, as shown in FIG. 2, are first to fifth fiber reinforced resin prepregs 11 to 15 cut into a shape such that the orientation angle of the reinforced fibers is a predetermined angle, and a four-axis woven fabric. It consists of reinforced prepreg 10. The golf shaft 1 is formed by sequentially winding the prepregs 10 and 11 to 15 around the mandrel 7 and laminating them.

  Usually, in forming the golf shaft 1, in addition to these prepregs 10, 11-15, another prepreg is partially disposed on the front end side or rear end side of the shaft 1 for reinforcement. The description is omitted.

  In the first to fifth fiber reinforced resin prepregs 11 to 15 and the four-axis fabric reinforced prepreg 10, carbon fibers are used as the reinforcing fibers, and an epoxy resin is used as the matrix resin. The reinforcing fibers are not limited to carbon fibers, and glass fibers, aramid fibers, boron fibers, aromatic polyamide fibers, aromatic polyester fibers, ultrahigh molecular weight polyethylene fibers, and the like can also be used.

  The matrix resin is preferably a thermosetting resin typified by the epoxy resin. For example, unsaturated polyester resin, phenol resin, melamine resin, urea resin, diallyl phthalate resin, polyurethane resin. , Polyimide resin, silicon resin and the like.

  As shown in FIG. 3, the four-axis fabric layer 4 forming the four-axis fabric reinforced prepreg 10 includes a plurality of longitudinal yarns 41 and a plurality of transverse shaft yarns 42 woven so as to be orthogonal to each other. A set of a plurality of oblique shaft yarns 43 woven so as to cross the left and right (the + direction and the − direction) with respect to the vertical axis yarn 41 and the horizontal axis yarn 42 are provided. The vertical yarn 41 of the four-axis fabric layer 4 is arranged parallel to the longitudinal direction of the shaft 1, the horizontal yarn 42 is arranged perpendicular to the longitudinal direction of the shaft, and the oblique axial yarn 43 is arranged on the shaft. It arrange | positions so that it may cross with respect to a longitudinal direction.

  Since the longitudinal thread 41 needs to be strong against bending along the axis of the shaft 1, a high-strength reinforcing fiber is used as the reinforcing fiber. For example, carbon fibers having a tensile strength of 3500 to 7000 MPa are preferably used. The horizontal shaft thread 42 requires a material having a higher spring constant as the golfer's force increases. The golfer's ability can be expressed by the head speed and the maximum deflection of the shaft 1 during the swing. As the head speed increases and the maximum deflection of the shaft 1 increases, a heavier and harder shaft is required. Therefore, the higher the shaft 1 is heavier and the harder, the higher the elastic modulus of the reinforcing fiber employed for the horizontal shaft thread 42 is better. When carbon fiber is used as the reinforcing fiber constituting the horizontal axis thread 42, carbon fiber having a tensile modulus of 240 to 800 GPa is preferable. In order to obtain the same effect, it is possible to increase the fineness of the carbon fiber or increase the number of fibers converged to form one horizontal axis thread 42. In this case, since the unevenness of the shaft surface becomes large, it is necessary to increase the polishing allowance of the outermost layer. From such a viewpoint, the fineness of the reinforcing fibers of the four-axis fabric layer is preferably 50 tex to 200 tex. The unit of fineness tex is a value equal to the number of grams per 1000 m of fibers (1 tex = 1 g / 1000 m).

  In the step of weaving the fibers in the horizontal axis direction, the reinforcing fibers tend to have a higher tensile elastic modulus as the golfer's ability increases, but the fibers having a higher elastic modulus tend to have lower tensile strength. Further, the influence of the yield due to fiber breakage is increased. Therefore, regarding the tensile elastic modulus of the horizontal axis thread 42, a carbon fiber of 240 to 500 GPa is more preferable.

  The oblique shaft yarn 43 is a shaft yarn that most affects the attenuation of bending vibration. In the present embodiment, it is considered that the behavior of the shaft can be specified by the characteristic of “playing”. That is, in the present embodiment, the vibration representing the bending of the shaft during the swing is sensed by the golfer, and the vibration caused by hitting the ball is sensitive.

  In the case of obtaining the characteristic by the sensory expression of “play” and “stable” on the shaft, in order to make the damping ratio of the bending vibration as small as possible, the reinforcing fiber constituting the oblique shaft yarn 43 has a high elastic modulus reinforcement. Fibers are used so that the orientation angle with respect to the axis of the shaft 1 is ± 45 degrees. As the reinforcing fiber, it is preferable to use a carbon fiber having a tensile elastic modulus of 400 to 800 GPa. The higher the tensile modulus, the better. However, in the process of weaving the fibers along the oblique axis, the higher the elastic modulus, the lower the tensile strength of the fiber. Therefore, 400 to 500 GPa of carbon fiber is more preferable. Further, it is preferable that the reinforcing fiber used for the oblique axis yarn 43 has the same characteristics in the + direction oblique axis and the − direction oblique axis. This is because if the characteristics are different between the + direction and the-direction, anisotropy occurs in the twist characteristics.

  In order to obtain an effect with respect to “bounce” which is a desired vibration characteristic, the four-axis fabric layer preferably has a low vibration damping rate, and for this purpose, the resin amount of the prepreg needs to be reduced. This is because the attenuation coefficient of the resin itself is lower than that of the reinforcing fiber. In addition, regarding the prepregs 10 to 15 that form other fiber reinforced resin layers including the four-axis woven fabric layer 4, the resin content is in the range of 20 to 50% by weight of the weight of each prepreg. Suitable for both manufacturing and manufacturing. The ratio of the resin used for all the prepregs 10 to 15 to the entire golf shaft 1 is preferably in the range of 20 to 30% by weight.

  In order to efficiently achieve the object of the present invention, it is more effective to dispose the four-axis woven fabric layer 4 on the outermost side, but depending on the manufacturing method and appearance requirements, not the outermost side, It is preferable to arrange it at a position closer to the outermost side, and it is preferable to arrange it from the outermost layer to the second layer.

  When the shaft 1 made of fiber reinforced resin is formed by a so-called sheet wrapping method, after winding a plurality of prepregs 10-15 around the mandrel 7 and then winding and fixing the wrapping tape, this is cured and molded. The lapping tape is removed, the surface is polished and painted to obtain the finished shaft.

  When such a manufacturing method is employed, one prepreg 15 layer is provided outside the prepreg 10 provided with the four-axis fabric layer 4 in order to secure a polishing allowance. The thickness of the prepreg 15 is preferably 0.02 mm to 0.15 mm. When the thickness of the prepreg 15 is 0.02 mm or less, the reinforcing fibers of the four-axis fabric layer 4 are erroneously polished by polishing, which may adversely affect the performance of the shaft 1, which is not preferable. When the thickness of the prepreg 15 is 0.15 mm or more, the distance from the surface of the prepreg 15 to the four-axis woven fabric layer 4 is increased, so that it is difficult to obtain the effect of arranging the four-axis woven fabric layer 4.

  On the other hand, a thick prepreg 15 is required in the following cases. That is, each axial yarn 41, 42, 43 of the 4-axis fabric layer 4 is formed by converging 1000 to 6000 carbon fibers, and each axial yarn 41, 42, 43 has a tensile elastic modulus, for example. In the case where 3000 pieces of 240 GPa carbon fibers are converged and used in the case where 1000 pieces of carbon fibers are converged, the case where 3000 fibers are converged and used is 4 at the intersection of the axial yarns 41, 42, and 43. The thickness of the shaft fabric layer 4 is increased. Therefore, when the shaft surface is made smooth, it is necessary to take a lot of polishing allowance. Therefore, in such a case, it is necessary to increase the thickness of the prepreg 15. Here, a bundle of 3000 carbon fibers converged is generally called 3K. K corresponds to 1000.

  Manufacturing methods that do not require polishing after curing, such as a method in which a prepreg is coated with a stretchable tube instead of a wrapping tape, an internal pressure molding method, or even the sheet wrapping method In the case where no is required, the 4-axis woven reinforced prepreg 10 can be used as the outermost layer.

  The first and second fiber reinforced resin prepregs 11 and 12 are disposed by being wound 2 to 4 times over the entire length of the shaft, and the reinforcing fibers are ± 30 ° to ± 65 ° with respect to the longitudinal direction of the shaft 1. It is arranged to make an angle. The third fiber reinforced resin prepreg 13 is arranged so as to be wound once over the entire length of the shaft 1, and the reinforcing fibers are arranged so as to form an angle of approximately 90 degrees with respect to the longitudinal direction of the shaft 1. . The 4th and 5th fiber reinforced resin prepregs 14 and 15 are disposed by being wound 1-2 times over the entire length of the shaft 1 so that the reinforcing fibers are substantially parallel to the longitudinal direction of the shaft 1. Has been placed. However, as described above, the fifth fiber reinforced resin prepreg 15 may not be used depending on the manufacturing method.

  The shaft 1 of this embodiment is formed by a sheet winding method. In forming the shaft 1, the first to fourth fiber reinforced resin prepregs 11 to 14, the four-axis woven prepreg 10, and the fifth fiber reinforced resin prepreg 15 are wound around the mandrel 7 in this order and laminated, and a wrapping tape is provided on the outer periphery thereof. To obtain a laminate. In this state, the laminate is heated and pressurized, cured and molded, and then the mandrel is pulled out of the laminate to obtain the shaft 1.

  As described above, the golf shaft 1 of the present invention uses reinforced fibers having different characteristics for each axial yarn so as to satisfy the requirements for each axial yarn of the shaft 1, and woven them together. The four-axis fabric layer 4 is present in the shaft fabric layer 4 at the same time, and is disposed at a position closer to the outer layer in the prepreg laminate. Thereby, in the specification set for the golf shaft, the spring constant is increased and the loss factor in the first and second vibration modes is decreased so that the behavior of the shaft at the time of swing can be sensed. It is possible to produce a more stable shaft while at the same time being able to sense a “play” feeling.

Hereinafter, Examples 1 to 4 and Comparative Example 1 of the golf shaft of the present invention will be described.
Tables 1 and 2 show the configuration of the four-axis fabric reinforced prepreg 10 used in each example and the lamination conditions of the fiber reinforced resin prepreg used in the comparative example. The length of each shaft is 45 inches (1143 mm).

（実施例１）
図２に示す実施形態におけるプリプレグの積層構成を採用し、第１〜第５繊維強化樹脂プリプレグ１１〜１５、および、表１の実施例１の欄に示す構成の４軸織物プリプレグ１０をマンドレル７に巻き付けて積層した。４軸織物強化プリプレグ１０として、斜交軸糸４３の強化繊維には、引張り弾性率；３８５ＧＰａの炭素繊維を３０００本収束した繊維を使用した。縦軸糸４１および横軸糸４２には、強化繊維として引張り弾性率；２４０ＧＰａの炭素繊維を１０００本収束した繊維を使用した。表１中、１０００本の束を１Ｋで示す。

Example 1
The laminated structure of the prepreg in the embodiment shown in FIG. 2 is adopted, and the first to fifth fiber reinforced resin prepregs 11 to 15 and the four-axis woven prepreg 10 having the structure shown in the column of Example 1 in Table 1 are mandrel 7. Wound around and laminated. As the four-axis woven reinforced prepreg 10, a fiber in which 3000 carbon fibers having a tensile elastic modulus of 385 GPa are converged is used as the reinforcing fiber of the oblique shaft yarn 43. For the vertical thread 41 and the horizontal thread 42, fibers obtained by converging 1000 carbon fibers having a tensile modulus of 240 GPa as reinforcing fibers were used. In Table 1, 1000 bundles are indicated by 1K.

  As the first and second fiber reinforced resin prepregs 11 and 12, prepregs obtained by impregnating carbon fibers having a tensile elastic modulus of 445 GPa with a synthetic resin so that the resin content was 25 wt% were used. The thickness of the prepreg after molding is 0.061 mm. The orientation angles of the reinforcing fibers in the prepregs 11 and 12 are + 45 ° and −45 °, respectively, with respect to the longitudinal direction of the shaft.

  As the third fiber reinforced resin prepreg 13, a prepreg obtained by impregnating a carbon fiber having a tensile elastic modulus of 240 GPa as a reinforced fiber with a synthetic resin so that the resin content is 25 wt% was used. The thickness of the prepreg after molding is 0.045 mm.

  As the fourth fiber reinforced resin prepreg 14, a prepreg obtained by impregnating a carbon fiber having a tensile elastic modulus of 300 GPa as a reinforcing fiber with a synthetic resin so that the resin content is 25 wt% was used. The thickness of the prepreg after molding is 0.081 mm.

The 4-axis fabric reinforced prepreg 10 was disposed in the outermost layer of the laminate to form a shaft. The weight of the shaft was 63 g.
(Example 2)
The reinforcing fiber of the horizontal axis yarn 42 of the 4-axis woven fabric reinforced prepreg 10 of Example 1 was changed to a fiber in which 3000 carbon fibers having a tensile modulus of 240 GPa were converged. Others were the same as Example 1.

(Example 3)
The reinforcing fiber of the horizontal axis yarn 42 of the 4-axis woven fabric reinforced prepreg 10 of Example 1 was changed to a fiber in which 3000 carbon fibers having a tensile elastic modulus of 385 GPa were converged. Others were the same as Example 1.

(Example 4)
The oblique shaft yarn 43 of the four-axis fabric-reinforced prepreg 10 of Example 1 was changed to a fiber in which 1000 carbon fibers having a tensile elastic modulus of 240 GPa were converged. Others were the same as Example 1.
(Comparative Example 1)
The 4-axis fabric layer 4 was eliminated from Example 1, and the fourth fiber-reinforced resin prepreg 14 was changed. The fourth fiber reinforced resin prepreg 14 is pulled as a reinforced fiber so that the EI value, the shaft weight, and the outer diameter are not significantly different from those of Examples 1 to 4 by eliminating the four-axis fabric layer 4. Elastic modulus: A prepreg obtained by impregnating carbon fiber of 300 GPa with a synthetic resin so that the resin content was 25 wt% was used. The thickness of the prepreg after molding is 0.081 mm and 0.101 mm. Others were the same as those in Examples 1 to 4.

  The golf shafts of Examples 1 to 4 and Comparative Example 1 were measured and evaluated for vibration damping, EI value, and spring constant by the methods described later. Each evaluation result is described in the lower column of Tables 1 and 2. In addition, among the sensory tests, tests relating to stability are shown in Table 3.

(Measurement of vibration damping)
As shown in FIG. 4, the vibration attenuating property is an acceleration pickup (illustrated) in which the position of the center of gravity of the golf shaft 1 is fixed to the vibrator 5, the shaft 1 is vibrated, and the vibration transmission is attached to the shaft 1. The loss factor η was calculated by the loss factor measuring device 6 from the detected data. The following equations were used to calculate the primary and secondary loss factors. ξ represents an attenuation rate.

η = 2ξ
(Measurement of EI value (bending stiffness value))
As shown in FIG. 5, the golf club shaft is tilted at a position 200 mm away from the grip end of the golf shaft 1 according to the three-point bending test method of the golf club shaft specified by the CONSUMER PRODUCT SAFETY ASSOCIATION. The amount of deflection was measured. As shown in FIG. 5, the shaft 1 is pressed by the pressing member 63 while being supported by the two supports 61 and 62. The span between the two supports 62 is represented by L, and the pressure position is set in the middle of the span L. Therefore, the length L1 from the pressing position to the right support 61 and the length L2 from the pressing position to the left support 62 are equal.

Then, the bending rigidity value, that is, the EI value was obtained by the following calculation formula showing the relationship between the deflection amount δ and the load W when the shaft 1 was pressurized.
EI = W / δ × L ³
(Measurement of spring constant)
The spring constant is measured in accordance with the golf club certification standard and the standard confirmation method (product safety association) S-type shaft flat test. In the flat test method, when a constant load P is applied at a load speed of 5 mm / min within a range of 50 mm from the grip end, the spring constant K is obtained from the load P and the displacement amount Δ at that time by the following equation. .

K = P / Δ
The spring constant K was measured for use as an indicator of shaft “stability” and “tightness”.
The measurement results of various characteristics are shown in Tables 1 and 2.
When Examples 1 to 4 and Comparative Example 1 are compared, the bending rigidity (EI value), torsional rigidity (torque), and weight of the shaft are comparable. The torque is fixed at the front and rear ends of the shaft, and when a twisting load of 1 pound (about 0.45 kg) per foot (about 0.3 m) is applied to the shaft, the angle at which the shaft is twisted ( (°).

(Sensory test)
Golf clubs were manufactured by attaching heads and grips to the shafts of the examples and comparative examples. A test was conducted by four golfers. By the sensory test, “stability”, “play” and “stickiness” were evaluated by trial hits.

  As a result of the sensory test on “bounce” and “stickiness”, the shaft of Example 3 obtained the highest evaluation of “bounce” and “stability”. The order was that of Comparative Example 1. That is, the shaft having the four-axis fabric layer 4 and the shaft having a higher tensile elastic modulus of the reinforcing fibers of the oblique axis yarn and the transverse axis yarn improved the “feel”.

  Next, a vibrator was attached to the center of gravity of these shafts, and the vibration characteristics (vibration attenuation) were investigated. For the shafts of Examples 1-4 and Comparative Example 1, since the weight and rigidity are equal, no difference in natural frequency is recognized. However, it can be seen that the loss coefficient representing the damping ratio in each vibration mode is different. Regarding vibration damping, the damping ratio ζ can be obtained by the following equation.

ζ = c / 2 (mk) ^1/2
Here, c is a damping coefficient determined by the material, m is weight, and k is an elastic modulus. The smaller the damping ratio, the higher the sensory evaluation of “playing”. In order to obtain a sensory evaluation that “playing” is good, it is necessary to reduce the damping ratio, which can be achieved by using a material having a high elastic modulus.

  Among the sensory tests, Examples 1 to 4 and Comparative Example 1 were evaluated for “stability”. The results are shown in Table 3. In comparison with Comparative Example 1, evaluation was performed with 1 being the best feeling, 2 being good, 3 being rather good, and 4 being equivalent.

表３からわかるように、プロゴルファーによる試打評価の結果、「かたさ感」に影響する曲げ剛性値（表１、２中のＥＩ値）は、各実施例１から４において、ほとんど同等であるにもかかわらず、「安定感」はかなり異なる評価であった。この中でも、ヘッドスピード（Ｈ／Ｓ）の速い、もしくはスイングテンポの速いプロゴルファーＢ及びＡには、バネ定数の高い実施例２及び実施例３のシャフトは、「しっかりしている」と感じられるために、「安定感」について高評価であった。

As can be seen from Table 3, as a result of trial hitting evaluation by a professional golfer, the bending stiffness value (EI value in Tables 1 and 2) that affects the “feel of hardness” is almost the same in each of Examples 1 to 4. Regardless, “stability” was a fairly different evaluation. Among them, the professional golfers B and A having a high head speed (H / S) or a fast swing tempo feel that the shafts of Examples 2 and 3 having a high spring constant feel “solid”. In addition, the “stability” was highly evaluated.

  The inventor has the knowledge that the swing tempo can be expressed by the maximum amount of deflection of the shaft. That is, if the head speed is fast or the swing tempo is fast, the bending moment applied to the shaft during the swing increases, and as a result, the amount of bending of the shaft increases, and the faster the swing tempo, the less the amount of bending. In addition, I think that a hard shaft is necessary. As an apparatus for discriminating this, the present inventors invented Japanese Patent No. 3061640 (WO96 / 11726).

From the above results, it can be seen that not only the bending of the shaft but also the spring constant affects the stability. Therefore, in order to obtain a shaft with good “playing” and a more stable feeling, it is necessary to reduce the bending vibration attenuation and set the spring constant according to the golfer's ability.

Claims (7)

  A golf shaft made of a fiber reinforced resin formed by laminating a plurality of fiber reinforced resin layers, wherein the fiber reinforced resin layer includes a four axis woven layer obtained by reinforcing a four axis woven fabric with a molding resin, A plurality of longitudinal yarns extending parallel to the longitudinal direction of the shaft, a plurality of transverse yarns extending along a direction perpendicular to the longitudinal direction of the shaft, It is composed of oblique shaft yarns, and at least one of the longitudinal, horizontal and oblique shaft yarns is formed of reinforcing fibers having characteristics different from those of other shaft yarns. A golf shaft characterized by that.   The reinforcing fiber of the vertical axis yarn is made of carbon fiber having a tensile strength of 4000 MPa to 7000 MPa, and the reinforcing fiber of the horizontal axis yarn is made of carbon fiber having a tensile elastic modulus of 240 GPa to 800 GPa. The golf shaft according to claim 1, wherein the fiber is made of carbon fiber having a tensile modulus of 400 GPa to 800 GPa.   The golf shaft according to claim 1 or 2, wherein the fineness of the reinforcing fibers of the four-axis fabric layer is 50 tex to 200 tex (g / 1000 m).   4. The golf shaft according to claim 1, wherein the four-axis fabric layer is disposed in an outermost layer or a second layer from the outermost layer. 5.   The golf shaft according to claim 1, wherein a resin content of the fiber reinforced resin layer of the golf shaft is 20% to 30% of the total weight of the golf shaft.   5. The golf shaft according to claim 1, wherein the golf shaft has a tapered shape in which an outer diameter gradually increases from a front end toward a rear end. A golf club comprising the golf shaft according to any one of claims 1 to 6, wherein a head is attached to a tip of the golf shaft, and a grip is attached to a rear end thereof.

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