WO2005065785A1

WO2005065785A1 - Golf shaft

Info

Publication number: WO2005065785A1
Application number: PCT/JP2004/008815
Authority: WO
Inventors: Takeshi Saito; Susumu Hironaka; Yasushi Matsui
Original assignee: Mizuno Corporation; Mizuno Technics Corporation
Priority date: 2003-12-26
Filing date: 2004-06-23
Publication date: 2005-07-21
Also published as: JPWO2005065785A1

Abstract

A fiber-reinforced resin golf shaft formed by laminating a plurality of fiber-reinforced resin layers, wherein the fiber-reinforced resin layers comprise tetraxial fabric layers formed by reinforcing tetraxial fabric with a molding resin. The tetraxial fabric is formed of a plurality of vertical axis yarns extending parallel with the longitudinal direction of the shaft, a plurality of lateral axis yarns extending along a direction orthogonal to the longitudinal direction of the shaft, and one set of a plurality of oblique axis yarns obliquely crossing with each other bilaterally with respect to the longitudinal direction of the shaft. At least one type of the axis yarns of the vertical axis yarns, lateral axis yarns, and oblique axis yarns are formed of fiber-reinforced fibers having characteristics different from those of the other axis yarns.

Description

Specification

Gonolev shaft technical field

TECHNICAL FIELD [0001] The present invention relates to a gonofleft shaft having a vibration characteristic with a good feel and improved timing.

Background art

[0002] The timing of a golf club at the time of swing differs depending on the characteristics, weight, length, center of gravity, hardness, and the like of a player and a golf shaft. Various improvements have been made to the golf shaft to facilitate this timing. Golf shaft design items related to timing include shaft flex. It is known that this shaft flex is controlled by the amount of bending and the natural frequency when a certain weight is added to the tip of the golf shaft by fixing a gonolef shaft near its grip.

[0003] The amount of bending of the shaft during a swing is a combination of deformation due to bending in a direction along the axis of the golf shaft and deformation due to compression in a radial direction perpendicular to the axis. Therefore, if the deformation due to the compression is large, it interferes with the deformation due to the bending, making it difficult to feel the golfer's force S, and the restoring force of the golf shaft is also reduced, resulting in a problem that the flight distance is lost.

[0004] Therefore, when a golfer selects a flex that is easy to take timing, it is necessary to consider the radial rigidity of the golf shaft. In order to simultaneously satisfy the demands for deformation due to bending and radial deformation, a multilayer material consisting of multiple layers of thin pre-preda is used as the shaft material, or a multi-axial fabric is used. It is known to do.

[0005] In a golf shaft made of a fiber-reinforced resin, a shaft using a woven fabric, particularly a multiaxial woven fabric mainly composed of three axes, is disclosed in JP-A-58-76559, JP-A-3-151989, and It is described in Japanese Utility Model Application Laid-Open No. 51970/1991. The gonolev shafts described in these documents use the characteristics of triaxial fabrics to reinforce structures or improve productivity. Multiaxial fabrics are used.

[0006] Also, Hiroshi Fukuda, "Design of Composite Materials", Journal of the Textile Machinery Society, Japan Textile Machinery Society, November 25, 1994, Vol. 47, No. 11, p. 467-472. There is a description that the 4-axis woven fabric has the effect of a quasi-isotropic material, and that "the same properties are exhibited regardless of the directional load applied", and the advantages as a structure are discussed. .

[0007] Further, JP-A-2000-245880 describes a golf shaft using a four-axis fabric. This golf shaft is excellent in bending, torsion, and compression rigidity by using 4-axis woven fabric, has sufficient strength even when force in all directions is applied, and has a good balance of restoring force with high reactivity. It is said that a good golf shaft can be obtained.

Disclosure of the invention

[0008] A golf shaft using a multiaxial woven fabric such as the three-axis woven fabric or the four-axis woven fabric utilizes a quasi-isotropy or the like which is a feature 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 lateral direction perpendicular to the longitudinal direction, and the oblique direction having a predetermined angle with respect to the longitudinal direction. To cope with these, different characteristics are required in each direction. However, each of the above-mentioned documents does not disclose such a problem at all.

[0009] In addition, when specifying the performance of a Gonolev shaft, a sensory expression such as "play" or "stick" is used in addition to the mechanical characteristics. Such sensory expressions are often used by golfers, especially for advanced players, and have not yet been specified as physical quantities. Therefore, the means to devise a “flick” shaft is not clear at present.

[0010] Therefore, an object of the present invention is to provide a gonolef shaft having excellent mechanical properties and capable of satisfying demands for properties based on a sensory expression such as "flicking" and a sense of stability. Is what you do.

[0011] The present invention has been made to achieve the above object, and a golf shaft according to an embodiment of the present invention is made of a fiber reinforced resin obtained by laminating a plurality of fiber reinforced resin layers. The fiber reinforced resin layer includes a four-axis woven fabric layer obtained by reinforcing a four-axis woven fabric with a molding resin, and the four-axis woven fabric has a plurality of longitudinal threads extending parallel to the longitudinal direction of the shaft and a direction perpendicular to the longitudinal direction of the shaft. A plurality of horizontal threads extending along the shaft, It is composed of a set of a plurality of oblique shaft yarns. At least one of the vertical axis yarn, the horizontal axis yarn, and the oblique axis yarn is formed of a reinforcing fiber having characteristics different from those of the other axis yarns.

[0012] The reinforcing fiber of the vertical axis yarn has a tensile strength of carbon fiber strength of 4000MPa and 7000MPa, and the reinforcing fiber of the horizontal axis yarn has a tensile modulus of 240GPa and carbon fiber of 800GPa. The reinforcing fibers are preferably made of carbon fibers having a tensile modulus of 400 GPa and 800 GPa.

[0013] The fineness of the reinforcing fibers of the four-axis woven fabric layer is preferably 50tex-200tex (g / 1000m).

The four-axis woven fabric layer is preferably arranged at the outermost layer or at 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 Gonoref shaft.

[0014] The Gonoref shaft may have a tapered shape whose outer diameter gradually increases from the front end to the rear end.

It is possible to construct a gonolev club by attaching the head to the tip of any of the preferable golf shafts described above and attaching the grip to the trailing end.

Brief Description of Drawings

FIG. 1 is a front view showing a gonolef shaft according to an embodiment of the present invention.

FIG. 2 is a view for explaining a fiber reinforced resin pre-preda used for the golf shaft of FIG. 1.

FIG. 3 is a view showing a configuration of a four-axis woven fabric.

FIG. 4 is a perspective view for explaining a method of measuring a vibration damping characteristic of a shaft.

FIG. 5 is a diagram for explaining a method of measuring an EI value of a shaft.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described in detail.

FIG. 1 shows a gonolef 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 tapered shape in which the outer diameter gradually increases from the front end to the rear end. A head 2 is mounted on the front end on the small diameter side, and the grip is mounted on the rear end on the large diameter side. 3 is installed Has been.

[0017] The fiber reinforced resin layer is formed using a plurality of fiber reinforced resin pre-preda. As shown in FIG. 2, these fiber-reinforced resin pre-preders are a first-fifth fiber-reinforced resin pre-predder 11-11 cut into a shape such that the orientation angle of the reinforcing fibers is a predetermined angle, and a four-axis woven fabric. Strengthening prepredder 10 and power. The golf shaft 1 is formed by sequentially winding these pre-predaders 10, 11 and 15 around the mandrel 7 and laminating them.

[0018] Normally, in forming the golf shaft 1, another pre-predder is partially disposed on the front end side or the rear end side of the shaft 1 for the purpose of reinforcement by the force of the pre-preders 10, 11 and 15. Here, the description is omitted.

[0019] In the first to fifth fiber reinforced resin pre-predators 11 to 15 and the 4-axis woven fabric pre-predator 10, carbon fiber is used as the reinforcing fiber, and epoxy resin is used as the matrix resin. Glass fibers, aramide fibers, boron fibers, aromatic polyamide fibers, aromatic polyester fibers, ultra-high molecular weight polyethylene fibers, etc., which are not limited to carbon fibers, can be used as the reinforcing fibers.

As the matrix resin, a thermosetting resin represented by the above-mentioned epoxy resin is preferable. For example, unsaturated polyester resin, phenol resin, melamine resin, urea resin, diaryl phthalate Resin, polyurethane resin, polyimide resin, silicone resin and the like.

As shown in FIG. 3, the four-axis woven fabric layer 4 forming the four-axis woven fabric pre-predader 10 includes a plurality of vertical yarns 41 and a plurality of horizontal yarns 42 woven so as to intersect each other. And a set of a plurality of oblique shaft yarns 43 woven so as to intersect these left and right yarns 41 and 42 in the left and right directions (+ and-directions). The longitudinal axis thread 41 of the four-axis fabric layer 4 is arranged parallel to the longitudinal direction of the shaft 1, the transverse axis thread 42 is arranged perpendicular to the longitudinal direction of the shaft, and the oblique axis thread 43 is It is arranged so as to be oblique to the longitudinal direction.

[0022] 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 700 OMPa are preferably used. For the horizontal thread 42, a material having a higher spring constant is required as the golfer's power becomes higher. The golfer's ability depends on head speed and speed. And the maximum amount of 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 heavier and harder the shaft 1, the better the elastic modulus of the reinforcing fiber used for the horizontal thread 42 is. When carbon fiber is used as the reinforcing fiber constituting the horizontal 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 to increase the number of fibers bundled to form one horizontal thread 42. In that case, the roughness of the shaft surface becomes large, so that the polishing allowance of the outermost layer needs to be increased. From this viewpoint, the fineness of the reinforcing fibers of the four-axis woven fabric layer is 50 tex / 200 tex. The unit of fineness, tex, is a value equal to the number of grams per 1000 m of fiber (ltex = lg / 1000 m).

[0023] The reinforcing fiber preferably has a higher tensile elastic modulus as the golfer's power becomes higher. However, a fiber having a higher elastic modulus tends to have a lower tensile strength. In the process of weaving fibers in the opposite direction, the effect of the yield due to fiber breakage becomes large. Therefore, regarding the tensile modulus of the horizontal yarn 42, carbon fiber of 240 to 500 GPa is more preferable.

[0024] 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 indicating the bending of the shaft during the swing is sensed by the gonofer, and the vibration caused by hitting the ball is sensed.

[0025] In the case where such a characteristic as "playing" and "stable" is required for the shaft, in order to minimize the bending vibration damping ratio, the reinforcing fibers constituting the oblique shaft yarn 43 have high elasticity. The reinforcing fibers are arranged so that the orientation angle with respect to the axis of the shaft 1 is ± 45 degrees. As the reinforcing fibers, it is preferable to use carbon fibers having a tensile modulus of 400 to 800 GPa. The higher the tensile modulus, the better. However, in the process of weaving the fiber along the oblique axis, the higher the modulus, the higher the modulus, the lower the tensile strength of the fiber. Carbon fiber is more preferred. Further, it is preferable that the reinforcing fibers used in the oblique shaft yarn 43 have the same characteristics in the + -direction oblique axis and the one-way oblique axis. If the characteristics differ between the + direction and the-direction, anisotropy occurs in the torsional characteristics. It is.

[0026] The four-axis woven fabric layer preferably has a low vibration damping rate in order to obtain the effect of "flicking" which is a desired vibration characteristic, and in order to achieve the effect, the resin amount of the pre-preda is also reduced. There is a need. This is because the damping coefficient of the resin itself is lower than that of the reinforcing fiber. In addition, regarding the pre-predeers 10 to 15 that form another fiber-reinforced resin layer including the four-axis fabric layer 4, if the resin content is within the range of 2050% by weight of the weight of each pre-prede, Suitable for both properties and manufacturing. It is preferable that the ratio of the resin used in all the pre-predas 10 to 15 to the entire gonolev shaft 1 is in the range of 20 to 30% by weight.

[0027] In order to efficiently achieve the object of the present invention, it is more effective to arrange the four-axis woven fabric layer 4 on the outermost side. It is preferable to arrange at a position closer to the outermost layer than the outermost layer, and it is preferable to arrange the layers 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, a plurality of pre-predaers 10-15 are sequentially wound around the mandrel 7, and then a wrapping tape is wound thereon and fixed. After curing and molding, the wrapping tape is removed, the surface is polished and painted to obtain the finished shaft.

When such a manufacturing method is adopted, one layer of the pre-preda 15 is provided outside the pre-preda 10 provided with the four-axis fabric layer 4 in order to secure a polishing allowance. The thickness of the prepreg 15 is preferably between 0.02 mm and 0.15 mm. If the thickness of the pre-preda 15 is 0.02 mm or less, the reinforcing fibers of the four-axis woven fabric layer 4 are erroneously polished by polishing, which may adversely affect the performance of the shaft 1, which is not preferable. If the thickness of the prepreg 15 is 0.15 mm or more, the surface force of the prepreg 15 also increases the distance to the four-axis fabric layer 4, so that the effect of disposing the four-axis fabric layer 4 is hardly obtained.

[0030] On the other hand, in the following cases, the pre-predator 15 needs to have a large thickness. That is, each of the yarns 41, 42, 43 of the four-axis fabric layer 4 is formed by converging 1,000 to 6,000 carbon fibers. 3000 carbon fibers with a rate of 240 GPa are converged and used, and 1000 carbon fibers are converged and used. When converged and used, the thickness of the 4-axis woven fabric layer 4 at the intersection of each of the thread 41, 42, and 43 becomes larger. Therefore, it is necessary to increase the polishing allowance when the shaft surface is made smooth. Therefore, in such a case, it is necessary to increase the thickness of the pre-preda 15. Here, a bundle of 3000 carbon fibers is generally called 3K. K corresponds to 1000.

[0031] A production method that does not require polishing after curing molding, for example, a method in which a pre-preda is covered with an extensible tube instead of a wrapping tape and molding is performed, or an internal pressure molding method is used, or the sheet wrapping method is used. In the case where polishing is not required even if there is, for example, the 4-axis woven fabric prepreg 10 can be used for the outermost layer.

[0032] The first and second fiber-reinforced resin pre-predators 11, 12 are disposed by being wound 2-4 times over the entire length of the shaft. They are arranged at an angle of 65 °. The third fiber-reinforced resin pre-predder 13 is provided by winding once over the entire length of the shaft 1, and the reinforcing fibers are arranged so as to form an angle of about 90 degrees with respect to the longitudinal direction of the shaft 1. . The fourth and fifth fiber reinforced resin prepregs 14 and 15 are disposed by winding one or two turns over the entire length of the shaft 1, and the reinforcing fibers are substantially parallel to the longitudinal direction of the shaft 1. Are arranged as follows. However, as described above, the fifth fiber-reinforced resin pre-preda 15 may not be used depending on the manufacturing method.

[0033] The shaft 1 of the present embodiment is formed by a sheet winding manufacturing method. In forming the shaft 1, the first to fourth fiber reinforced resin pre-predeers 11 to 14, the four-axis woven pre-predader 10, and the fifth fiber reinforced resin pre-preda 15 are wound around the mandrel 7 in this order, laminated, and wrapped around its outer periphery. Wind the tape 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.

[0034] As described above, the golf shaft 1 of the present invention uses reinforcing fibers having different characteristics for each axis yarn so as to satisfy the necessary requirements for each axis yarn of the shaft 1, and woven fabrics thereof. As a result, the four-axis woven fabric layers 4 are simultaneously present in one four-axis woven fabric layer 4, and such a four-axis woven fabric layer 4 is arranged at a position closer to the outer layer in the laminate of the pre-preda. As a result, in the specifications set for the golf shaft, the panel constant is large, and the primary and secondary vibration modes are used. By reducing the loss coefficient of the shaft, the behavior of the shaft at the time of swing can be sensed, so that a so-called "flicking" feeling can be sensed, and a more stable shaft can be manufactured.

Hereinafter, Examples 14 to 14 and Comparative Example 1 of the golf shaft of the present invention will be described.

Tables 1 and 2 show the configuration of the 4-axis woven fabric prepreg 10 used in each example and the lamination conditions of the fiber reinforced resin prepreg used in the comparative example. Both shafts are 45 inches (1143 mm) in length.

[Table 1]

[Table 2] Comparative Example 1

4 shaft weave crossed shaft thread

Material layer Vertical thread-

Horizontal thread ―

Arrangement position of 4-axis fabric layer No arrangement

Place

Shaft weight before painting (g) 61.9

Shaft tip diameter (mm) 8.9

Shaft rear end diameter (mm) 15. 63

Torque (degrees) 3.96

EI value (kgfmm ² ) 9.5

Spring constant 71

Loss factor (1st order) 0.

Loss factor (second order) 0 .0045

(Example 1)

The first to fifth fiber reinforced resin prepregs 11 to 15 and the four-axis woven fabric prepreg 10 having the configuration shown in the column of Example 1 in Table 1 are employed in the mandrel, employing the laminated structure of the prepreg in the embodiment shown in FIG. 7 and laminated. As the 4-axis woven fabric pre-predator 10, a fiber obtained by converging 3,000 carbon fibers having a tensile elasticity of 385 GPa was used as the reinforcing fiber of the oblique axis yarn 43. As the longitudinal axis yarn 41 and the horizontal axis thread 42, fibers obtained by converging 1,000 carbon fibers having a tensile modulus of elasticity of 240 GPa as reinforcing fibers were used. In Table 1, 1000 bundles are indicated by 1K

[0037] As the first and second fiber reinforced resin pre-predas 11, 12, pre-predas obtained by impregnating carbon fibers having a tensile elasticity of 445 GPa with a synthetic resin so as to have a resin content of 25 wt% were used. The thickness of the prepreg after molding is 0.06 lmm. In addition, the orientation angles of the reinforcing fibers in the pre-predators 11 and 12 are + 45 ° and −45 ° with respect to the longitudinal direction of the shaft, respectively.

[0038] As the third fiber-reinforced resin pre-predator 13, a prepreg obtained by impregnating carbon fibers having a tensile elasticity of 240 GPa as a reinforcing fiber with a synthetic resin so that the resin content becomes 25 wt% was used. The thickness of the prepreg after molding is 0.045 mm. As the fourth fiber reinforced resin pre-predator 14, a prepreg obtained by impregnating carbon fibers having a tensile elasticity of 300 GPa as a reinforcing fiber with a synthetic resin so as to have a resin content of 25 wt% was used. The thickness of the prepreg after molding is 0.081 mm.

The shaft was formed by disposing the four-axis woven prepreg 10 on the outermost layer of the laminate.

The weight of the shaft was 63 g.

(Example 2)

The reinforcing fibers of the horizontal thread 42 of the 4-axis woven fabric prepreg 10 of Example 1 were changed to fibers in which 3000 carbon fibers having a tensile modulus of elasticity of 2 40 GPa were converged. Others were the same as Example 1.

(Example 3)

The reinforcing fiber of the horizontal thread 42 of the 4-axis woven fabric prepreg 10 of Example 1 was changed to a fiber in which 3000 carbon fibers having a tensile elasticity of 3 85 GPa were converged. Others were the same as Example 1.

(Example 4)

The oblique axis yarn 43 of the 4-axis woven fabric prepreg 10 of Example 1 was changed to a fiber in which 1,000 carbon fibers having a tensile elasticity of 240 GPa were converged. Others were the same as Example 1. (Comparative Example 1)

Example 4 The four-axis woven fabric layer 4 was eliminated from the first embodiment, and the fourth fiber-reinforced resin pre-preda 14 was changed. In order to prevent the EI value, the shaft weight, and the outer diameter from being largely different from those in Examples 14 to 14 by eliminating the 4-axis woven fabric layer 4, the fourth fiber-reinforced resin pre-predator 14 was pulled as a reinforcing fiber. Elasticity modulus: A pre-predeer was used in which 300 GPa carbon fiber was impregnated with a synthetic resin so that the resin content was 25 wt%. The thickness of the prepreg after molding is two types, 0.081 mm and 0.11 mm. Others were the same as in Examples 1 to 4.

With respect to each of the Gonolev shafts of Examples 14 and 14 and Comparative Example 1, measurement and evaluation of the vibration damping property, the EI value, and the spring constant were performed by the methods described later. The results of each evaluation are shown in the lower columns of Tables 1 and 2. Table 3 shows the stability tests among the sensory tests.

(Measurement of vibration damping property) As shown in Fig. 4, the vibration damping is performed by fixing the position of the center of gravity of the gonolev shaft 1 to the force shaker 5, vibrating the shaft 1, and transmitting the vibration transmission to the acceleration pickup ( (Not shown), and a loss coefficient 77 was calculated by the loss coefficient measuring device 6 from the detected data. The following equations were used to calculate the primary and secondary loss factors. Indicates the decay rate.

[0045] η = 2 ξ

(Measurement of EI value (flexural rigidity value))

As shown in Fig. 5, according to the three-point bending test method for golf club shafts specified by the CONSUMER PRODUCT SAFETY ASSOCIATION, at a position 200 mm away from the grip end of golf shaft 1, And 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 pressing position is set in the middle of the span L. Accordingly, the length L1 from the pressing position to the right support 61 is equal to the length L2 from the pressing position force to the left support 62.

Then, a bending stiffness value, that is, a ΕΙ value was obtained by the following calculation formula showing the relationship between the amount of deflection δ and the load W when the shaft 1 was pressurized.

EI = W / δ χ L ³

(Measurement of panel constant)

The method of measuring the panel constant is in accordance with the flatness test of the S-shaped shaft of the golf club accreditation standards and the method of confirming the standards (Product Safety Association). In the flattening 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 panel constant K is calculated from the load P and the displacement Δ at that time by the following equation. Can be

[0047] Κ = Ρ / Δ

The spring constant Κ was measured to be used as an indicator of “stable feeling” and “stiffness and stiffness” of the shaft.

Tables 1 and 2 show the measurement results of various characteristics.

When Examples 1-4 and Comparative Example 1 are compared, the bending stiffness (ΕΙ value), torsional stiffness (torque), and weight of the shaft are comparable. Torque is fixed at the front and rear ends of the shaft. When a torsional load of 1 pound (approximately 0.45 kg) is applied to the shaft of one foot (approximately 0.3 m), the angle of the shaft is expressed in degrees (°).

[0048] (Sensory test)

A golf club was manufactured by attaching a head and a grip to the shaft of each example and each comparative example. The test was conducted by four golfers. The sensory test was used to evaluate the "stable feeling", "play" and "stickiness" by test hits.

[0049] As a result of the sensory test for "flicking" and "stickiness", the shaft of Example 3 was given the highest evaluation of "flicking" and "stable". 1, 4, and Comparative Example 1. In other words, the shaft having the four-axis woven fabric layer 4, and further the shaft having a higher tensile elastic modulus of the reinforcing fibers of the oblique axis yarn and the horizontal axis yarn, improved the feeling of “flipping”.

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

[0051] ζ = c / 2 (mk) ^1/2

Here, c is the damping coefficient determined by the material, m is the weight, and k is the elastic modulus. The lower the damping ratio, the higher the sensory evaluation of “play”. In order to obtain a good sensory evaluation of “popping”, it is necessary to reduce the damping ratio, which can be achieved by using a material having a high elastic modulus.

[0052] Among the sensory tests, with respect to "stable feeling", a comparative evaluation of Examples 14 to 14 and Comparative Example 1 was performed. The results are shown in Table 3. Compared to Comparative Example 1, the evaluation was made as 1 for the best feeling, 2 for the good feeling, 3 for what strength, and 4 for the equivalent.

[0053] [Table 3] Tester ABCD

H / S 48 ~ 49 49 ~ 50 43 ~ 44 42 ~ 43 Tempo Faster Comfortable Standard Faster

Example 1 3 3 1 1

Example 2 2 1 3 3

Example 3 1 2 4 4

Example 4 4 4 2 2 As can be seen from Table 3, the bending stiffness value (EI value in Tables 1 and 2) that affects the “hardness” as a result of the test hit evaluation by the professional golfer was determined in each of Examples 1 to 4. Although they were almost the same, “Stableness” was a very different evaluation. Among them, the professional golfers B and A with a high head speed (H / S) or with a fast swing tempo, said that the shafts of Example 2 and Example 3 with a high spring constant were "strong". It was highly evaluated for its “stableness” because it was felt.

[0054] The inventor has the knowledge that the swing tempo can be represented by the maximum deflection of the shaft. That is, if the head speed is high or the swing tempo is fast, the bending moment applied to the shaft during the swing increases, and as a result, the bending amount of the shaft increases, and the person with the faster swing tempo becomes the bending amount. We believe that a hard shaft is necessary to reduce the risk of stiffening. The present inventors have invented a patent 3061640 (W96 / 11726) as a device for determining this.

[0055] From the above results, it is clear that the panel constant, which is less than the bending of the shaft, affects the stability. Therefore, in order to obtain a more stable shaft with better “play”, it is necessary to reduce the bending vibration attenuation and set the panel constant in accordance with the golfer's ability.

Claims

The scope of the claims

[1] A golf shaft made of a fiber-reinforced resin obtained by laminating a plurality of fiber-reinforced resin layers, wherein the fiber-reinforced resin layer includes a 4-axis fabric layer obtained by reinforcing a 4-axis fabric with a molding resin. The shaft fabric is composed of a plurality of longitudinal yarns extending in parallel with the longitudinal direction of the shaft, a plurality of transverse yarns extending in a direction perpendicular to the longitudinal direction of the shaft, and a set of oblique lines extending left and right with respect to the longitudinal direction of the shaft. Wherein at least one of the longitudinal axis yarn, the transverse axis yarn, and the oblique axis yarn is a reinforcing fiber having characteristics different from those of the other axis yarns. A golf shaft characterized by being formed.

[2] 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 modulus of 240 GPa to 800 GPa. 2. The golf shaft according to claim 1, wherein the reinforcing fibers of the shaft yarn are made of carbon fibers having a tensile modulus of 400 GPa to 800 GPa.

3. The golf shaft according to claim 1, wherein the fineness of the reinforcing fibers of the four-axis woven fabric layer is 50 tex to 200 tex (g / 1000 m).

[4] The golf shaft according to any one of claims 1 to 3, wherein the four-axis woven fabric layer is arranged as an outermost layer or a second layer from the outermost layer.

[5] The Gonoref according to any one of claims 1 to 4, wherein the resin content of the fiber-reinforced resin layer of the Gonolev shaft is 20% to 30% of the total weight of the Gonolev shaft. shaft.

6. The gonolev shaft according to claim 1, wherein the gonolev shaft has a tapered shape whose outer diameter gradually increases from a front end to a rear end.

[7] A Gonoref club comprising the Gonoref shaft according to any one of claims 1 to 6, having a head mounted on a tip thereof, and a grip mounted on a rear end thereof.