JP2021159712A - Shaft for golf club, production method thereof - Google Patents

Abstract

To provide a shaft for a golf club comprising a long part whose external diameter is thin, comprising no part on which the external diameter varies suddenly, generating proper bending, achieving return of a head in impact time at proper timing according to swing of a player, and being suitable for various types of players and excellent in productivity, and a production method thereof.SOLUTION: There is provided a shaft for a golf club in which a plurality of fiber reinforced resin layers 2 including reinforced fibers are laminated, one end side of which is a thin diameter end 11 with a thin external diameter, the other end side of which is a thick diameter end 12 with a thick external diameter, and in which, when a length of a shaft 1 for a golf club is L1 (mm), in a longitudinal axis direction of the shaft 1 for a golf club, at least an external diameter D1 (mm) in a range from the thin diameter end 11 to a position A represented by a following formula (L1/3 (mm)) is 6 mm or greater and 10 mm or smaller and is constant, and an external diameter D2 (mm) of the thick diameter end 12 is 13 mm or greater and 15 mm or smaller.SELECTED DRAWING: Figure 1

Description

The present invention relates to a shaft for a golf club and a method for manufacturing a shaft for a golf club.

In general, fiber reinforced resins having a high degree of freedom in design and excellent strength characteristics are widely used for shafts for golf clubs. Further, in a golf competition, in order to extend the flight distance of a hit ball by improving the head speed, it is generally attempted to reduce the weight of the entire golf club by reducing the weight of the golf club shaft. Furthermore, in recent years, research has been conducted to improve the operability of golf clubs and improve their performance by optimizing the shape of the shaft for golf clubs.

For example, the shape of the golf club shaft is 60% in the length direction on the grip end side and 60% in the length direction on the tip end side, which is formed into a truncated cone shape having a substantially constant taper ratio. A shaft for golf clubs having a portion recessed and narrowed with respect to a reference surface extrapolated from the truncated cone shape on the grip end side has been proposed (see, for example, Patent Document 1). Further, in the golf club shaft of Patent Document 1, the drag force is proportional to the square of the air flow velocity, and the small diameter end portion of the golf club shaft moves at the highest speed during the swing, so that the tip end has a drag force. In recent years, the aerodynamic resistance of golf heads has been improved and the aerodynamic resistance of golf club shafts has become prominent (see paragraph 0005 of Reference 1). ~ 0017), etc. are described.

According to the shaft for golf clubs described in Patent Document 1, due to the above configuration, the flexural rigidity, weight, and the same bending rigidity and weight are the same as those of the shaft provided in the golf club based on the conventional example described in Table 1 of Patent Document 1. And while maintaining the balance point, the head speed can be increased by at least about 0.3 to 0.4 mph on average, and under appropriate conditions and environment, the flight distance of the ball due to the above head speed difference It is stated that can be extended by about 2 yard (see paragraph 0018 of the same paragraph).

Special Table 2019-531833

However, the golf club shaft described in Patent Document 1 has a tapered shape in which the tip end side of the tip greatly changes in outer diameter. Since a golf club shaft is generally cylindrical, its rigidity decreases as the outer diameter of the golf club shaft decreases. That is, in the configuration of the golf club shaft described in Patent Document 1, a portion having low rigidity is generated at the tip. Therefore, only the tip of the golf club is likely to be deformed during the swing, and as a result, the face of the head is delayed and returned during the swing, which makes it difficult to adjust the timing at the time of impact. More specifically, from the viewpoint of feeling and performance, for example, the feeling transmitted from the head to the player's hand changes, the operability feels unstable, and the whereabouts of the hit ball feel unstable. There was a problem.
On the other hand, the golf club shaft described in Patent Document 1 has an outer diameter similar to that of a golf club shaft generally used conventionally, except for the tip end side of the tip. The large diameter part was long, and the effect obtained was limited from the viewpoint of aerodynamic resistance.
Further, as described above, the golf club shaft described in Patent Document 1 has a sharply tapered tip end side, which makes it difficult to polish this portion, resulting in inferior productivity. rice field.

The present invention has been made in view of the above problems, and while a portion having a small outer diameter is long, there is no portion where the outer diameter changes abruptly, so that appropriate bending occurs and the player's swing is adjusted. The purpose is to provide golf club shafts that are preferred by various types of players and have excellent productivity because the head returns at the time of impact at a good timing, and a method for manufacturing golf club shafts. ..

The present inventors have made extensive studies to solve the above problems. As a result, in order to improve the feeling and the flight distance, the portion of the golf club shaft having a small outer diameter on the small diameter end side is long, and the thickness of the small diameter end portion is the conventional golf club shaft. It was found that the same degree as the above is thinner than the conventional shaft for golf clubs, so that it has a psychological effect that the player is likely to swing easily. Furthermore, they have found that by adopting the above shape, the aerodynamic resistance can be significantly reduced, and that a commercially available grip or head can be easily used, and the like, and the present invention has been completed.
That is, the present invention includes the following aspects.

[1] A golf club shaft formed by laminating a plurality of fiber-reinforced resin layers containing reinforcing fibers. The golf club shaft has a small-diameter end portion having a small outer diameter on one end side and a small-diameter end portion on the other end side. It is a large-diameter end with a large outer diameter, and when the length of the golf club shaft is L1 (mm), at least from the small-diameter end in the longitudinal axis direction of the golf club shaft, the following equation The outer diameter D1 (mm) in the range up to the position A represented by {L1 / 3 (mm)} is constant at 6 mm or more and 10 mm or less, and the outer diameter D2 (mm) of the large diameter end is 13 mm or more. A shaft for golf clubs characterized by being 15 mm or less.
[2] When the end on the large-diameter end side of the portion where the outer diameter D1 (mm) is constant is set to position C, 300 mm from the large-diameter end in the longitudinal axis direction of the golf club shaft. The golf club shaft according to the above [1], wherein the range between the position B and the position C is tapered and the taper rate in the range is constant.
[3] The above-mentioned [1] or [2], wherein at least one layer of the plurality of fiber-reinforced resin layers contains, as the reinforcing fibers, reinforcing fibers having an elastic modulus of 280 to 500 GPa over the entire length. Shaft for golf clubs described in.
[4] At least one of the plurality of fiber-reinforced resin layers is characterized by containing high-strength, high-elasticity reinforcing fibers having an elastic modulus of 280 to 500 GPa and a tensile strength of 5500 to 8500 MPa as the reinforcing fibers. The shaft for a golf club according to any one of the above [1] to [3].
[5] At least one of the plurality of fiber-reinforced resin layers is a layer in which a triangular prepreg is wound in a plan view, and the triangular prepreg is a small-diameter end of the golf club shaft. It is arranged on the portion side, and the length of the golf club shaft in the longitudinal axis direction is {L1 / 3-150 (L1 / 3-150) with respect to the length L1 (mm) starting from the small diameter end portion. The shaft for a golf club according to any one of the above [1] to [4], wherein the shaft is equal to or greater than mm)} and equal to or less than {L1 / 3 + 150 (mm)}.
[6] The method for manufacturing a golf club shaft according to the above [5], wherein at least a winding step of forming a plurality of fiber-reinforced resin layers by winding a plurality of prepregs around a mandrel is performed. In the winding step, the length of the golf club shaft in the longitudinal axis direction is {L1 / 3-150 mm or more, starting from the winding start position in the mandrel of the prepreg which is triangular in plan view. } Above, {L1 / 3 + 150 mm} or less, and wound directly on the mandrel, or wound on the prepreg wound on the mandrel to reinforce the plurality of fibers. A method for manufacturing a shaft for a golf club, which comprises forming at least one of the resin layers.

According to the golf club shaft according to the present invention, as described above, the outer diameter D1 from the small diameter end portion to at least the position A of 1/3 of the total length L1 is constant and 6 mm or more and 8 mm or less, and the large diameter. The shape is optimized by setting the outer diameter D2 of the end portion to 13 mm or more and 15 mm or less. As described above, the head looks relatively large because the outer diameter is narrowed over a long range of at least 1/3 of the total length L1 of the golf club shaft as compared with the conventional golf club shaft. Therefore, the visual effect that the head looks large when viewed from the state where the player holds the golf club can be obtained. This has the psychological effect of making it easier for the player to hit the head against the golf ball, thus improving performance. In addition, by reducing the aerodynamic resistance, swinging is improved and the head speed is improved. Further, since the outer diameters of the small-diameter end portion and the large-diameter end portion are the same as those of the conventional golf club shaft, it is possible to use a commercially available jig such as a grip, a head, or a sleeve.
In addition, since there is no place where the outer diameter changes significantly, polishing becomes easy at the time of production.
Therefore, it becomes possible to provide a shaft for a golf club which is excellent in operability and also excellent in productivity.

Further, according to the method for manufacturing a golf club shaft according to the present invention, by providing the winding process as described above, the outer diameter from the small diameter end to the position of 1/3 of the total length is predetermined. A golf club shaft having a constant thickness and a predetermined outer diameter at the end of a large diameter can be manufactured with high productivity without difficulty in polishing. That is, a golf club shaft having excellent operability can be manufactured with high productivity.

It is the schematic which shows typically the shaft for a golf club which concerns on this invention. It is a figure which schematically explains the manufacturing method of the shaft for a golf club which concerns on this invention, and is the schematic diagram which shows the mandrel used in the winding process of winding a prepreg and laminating a plurality of fiber reinforced resin layers. It is a figure explaining the example of the golf club shaft which concerns on this invention, and is the schematic diagram which shows the three-point bending test apparatus which measured the bending rigidity of the golf club shaft produced in the Example. It is a figure explaining the example of the golf club shaft which concerns on this invention, and is the schematic diagram explaining the method of measuring the balance point of the golf club shaft produced in the Example. It is a figure explaining the example of the golf club shaft which concerns on this invention, and is the schematic diagram which shows the measuring method of the kick point of the golf club shaft produced in the Example. It is a figure explaining the Example of the golf club shaft which concerns on this invention, and is the schematic diagram which shows the method of measuring the cantilever bending displacement amount of the golf club shaft produced in Example. It is a figure explaining the example of the shaft for golf clubs which concerns on this invention, and is the schematic diagram which shows the method of measuring the frequency of the shaft for golf clubs produced in Example. It is a figure explaining the example of the golf club shaft which concerns on this invention, and is the schematic diagram which shows the method of measuring the torque of the golf club shaft produced in the Example. It is a figure explaining the example of the shaft for a golf club which concerns on this invention, and is the pattern figure which shows the shape of the mandrel and the prepreg used for manufacturing the shaft for a golf club which is an Example of this invention. It is a figure explaining the example of the golf club shaft which concerns on this invention, and is the pattern figure which shows the shape of the mandrel and the prepreg used for manufacturing the golf club shaft of the comparative example 2 which has a conventional structure. It is a figure explaining the example of the golf club shaft which concerns on this invention, and is the graph which shows the relationship between the bending rigidity of the golf club shaft produced in the Example, and the distance from the small diameter end part of the golf club shaft. Is. It is a figure explaining the example of the golf club shaft which concerns on this invention, and shows the change in the outer diameter of the golf club shaft produced in the Example, according to the distance from the small diameter end part of the golf club shaft. It is a graph.

Hereinafter, embodiments of a golf club shaft and a method for manufacturing a golf club shaft according to the present invention will be described, and the drawings will be described as appropriate with reference to the drawings as necessary. In addition, in each drawing used in the following description, in order to make the feature easy to understand, the feature part may be enlarged and shown, and the dimensional ratio of each component may be different from the actual one. There is. Further, the materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

<Structure of golf club shaft>
In the golf club shaft according to the present invention, the outer diameter of the surface perpendicular to the axial direction changes from one end side to the other end side in the longitudinal axis direction, and the tapered portion and the tapered portion. It has both a part with a constant diameter.
Hereinafter, in the present embodiment, the end portion on the side having a small outer diameter is referred to as a small diameter end portion, and the end portion on the side having a large outer diameter is referred to as a large diameter end portion.

Further, the golf club shaft according to the present invention is used for a golf club for a driver, a fairway, or an iron, and for example, its length L1 (mm) (see FIG. 1) is in the range of 800 to 1200 mm. Is. Further, such a golf club shaft is provided with a head for hitting a ball on the small diameter end side, and a grip gripped by the player is provided on the large diameter end.

As shown in FIG. 1, the golf club shaft 1 described in the present embodiment is a golf club shaft in which a plurality of fiber-reinforced resin layers 2 including reinforcing fibers are laminated.
The golf club shaft 1 of the present embodiment has a small-diameter end portion 11 having a small outer diameter on one end side and a large-diameter end portion 12 having a large outer diameter on the other end side.

In the fiber-reinforced resin layer 2 of the golf club shaft 1 according to the present invention, for example, a sheet-shaped reinforcing fiber base material obtained by aligning a plurality of reinforcing fibers in one direction in the longitudinal direction of the fibers is impregnated with a matrix resin composition. The sheet-shaped matrix resin composition-impregnated reinforcing fiber base material (prepreg: see the pattern diagram in FIG. 9 etc.) is wound around the mandrel (core metal: see the mandrel 30 etc. in FIG. 2) multiple times. , This is heat-cured to form, and then the mandrel 30 is pulled out to produce a sheet wrapping method.

[Outer diameter and shape of golf club shaft]
As shown in FIG. 1, the golf club shaft 1 of the present embodiment has a small diameter end portion in the longitudinal axis direction of the golf club shaft 1 when the length of the golf club shaft 1 is L1 (mm). The outer diameter D1 (mm) in the range from 11 to at least the position A represented by the following equation {L1 / 3 (mm)} is constant, and the outer diameter D1 (mm) of the small diameter end portion 11 is constant. Is 6 mm or more and 10 mm or less.
Further, the outer diameter D2 (mm) of the large diameter end portion 12 of the golf club shaft 1 is 13 mm or more and 15 mm or less. The outer diameter D2 (mm) is the outer diameter including the design-imparting layer when the design-imparting layer described later is provided.
Further, in the golf club shaft 1 of the example shown in FIG. 1, when the end on the large diameter end portion 12 side of the portion where the outer diameter D1 (mm) is constant is set to the position C, the golf club shaft 1 In the longitudinal axis direction, the range between the position B and the position C at the large diameter end 12 to 300 mm is tapered, and the taper rate in the longitudinal axis direction is constant in the tapered range. It is configured. In the present embodiment, the region from the position B to the large diameter end portion 12 may have a taper, or may have a straight shape without a taper.

In the golf club shaft 1 of the present embodiment, first, the outer diameter D1 (mm) in the range from the small diameter end portion 11 to the position A is constantly limited to 6 mm or more and 10 mm or less, and further, the large diameter end portion 12 By limiting the outer diameter D2 (mm) of the golf club to 13 mm or more and 15 mm or less, the portion of the golf club shaft 1 having a small outer diameter is extremely long as compared with the conventional golf club shaft for drivers. That is, compared to the golf club shaft provided in the conventional golf club, first, the thin part on the head side is longer, so that even if a head of the same size as the conventional one is attached, the head can be seen from the player. You can get the visual effect of feeling big. This gives the player the psychological effect that the head is likely to hit the ball easily. Therefore, it is possible to obtain a sensory effect that the player can easily feel the swing. In addition, since the aerodynamic resistance is reduced, the flight distance is extended by increasing the head speed, and excellent performance can be obtained. On the other hand, since the outer diameter of the small diameter end portion 11 is the same as that of a conventional golf club shaft, a commercially available sleeve or jig can be used as it is. Further, since the outer diameter on the large diameter end portion 12 side is the same as that of the conventional golf club shaft, a commercially available grip can be used.

Further, in the present embodiment, the range between the position C and the position B shown in FIG. 1 is further tapered so that the diameter is gradually reduced from the position B side to the position C side, and the taper in the range is formed. It is more preferable to configure the rate to be constant. As a result, the taper degree of the region is reduced, so that the player feels a sense of perspective, and the player can easily operate the golf club because the visual effect that the head feels closer to the player can be obtained. You can also get the psychological effect of being able to feel it.

As described above, the golf club shaft 1 has an extremely long portion having a smaller outer diameter than the conventional golf club shafts for drivers, fairways, and irons. The space between them has a tapered shape with a constant taper ratio. That is, in the present embodiment, the lower limit of the outer diameter D1 (mm) on the small diameter end 11 side is limited to 6 mm, and the lower limit of the outer diameter D2 (mm) on the large diameter end 12 side is limited to 13 mm. ing. In order to obtain excellent feeling and performance when using a golf club, it is necessary to maintain a certain weight or more in addition to the hardness and strength as a golf club shaft as described above. Therefore, it is designed to secure the weight of the entire golf club shaft by limiting the outer diameter D1 (mm) and the outer diameter D2 (mm) to the extent that they are not too thin, and is commercially available. It is designed to enable the use of sleeves and grips.

The golf club shaft 1 of the present embodiment adopts a configuration that is thinner than the conventional golf club shaft over the entire length. In the conventional shaft for golf clubs, for example, a shape obtained by a method as described in Examples of JP-A-2014-061277 is generally used. The above-mentioned thickness of a conventional golf club shaft is set to, for example, an outer diameter of a certain value or more, thereby ensuring rigidity by an outer diameter effect (generally, in the case of a cylindrical shape, the outer diameter contributes most to rigidity). The design is designed to give strength to the golf club shaft by not excessively deforming the golf club shaft during a swing.

On the other hand, in the present embodiment, by limiting the outer diameter D1 and the outer diameter D2 to the above range, the above-mentioned problems such as the attachment of the conventional head and grip and the ease of gripping the grip do not occur, and golf is performed. The club shaft 1 can be made narrower over the entire length. That is, the outer diameter of the golf club shaft 1 is limited to about 70% of the outer diameter of the golf club shaft used for conventional drivers, fairways and irons over the entire length, and more preferably the length. By forming the middle portion in the axial direction into a tapered shape having a constant taper ratio, the psychological effect as described above and excellent performance can be obtained.

Further, in the present embodiment, it is more preferable that at least one layer of the plurality of fiber-reinforced resin layers 2 described in detail later is a layer formed by winding a triangular prepreg in a plan view (). See the prepreg of pattern 3 shown in FIG. 9). In the triangular prepreg as described above, for example, the length of the golf club shaft 1 in the longitudinal axis direction starts from the small diameter end portion 11 with respect to the length L1 (mm) of the golf club shaft 1. As a result, it is {L1 / 3-150 (mm)} or more and {L1 / 3 + 150 (mm)} or less. Further, the triangular shape of the prepreg is preferably a right-angled triangle, and one of the two sides of the right-angled triangle that is orthogonal to each other is with respect to the axial direction of the golf club shaft. They are arranged on the small diameter end 11 side so as to be orthogonal to each other (see the column of pattern 8 in FIG. 9). Further, the other side of the two orthogonal sides of the right-angled triangular prepreg is arranged and wound so as to correspond to the axial direction of the golf club shaft 1 over the entire length of the one side. Further, it is preferable that one of the two orthogonal sides of the right-angled triangular prepreg is shorter than the other, and the side arranged at the small-diameter end portion 11 is the short side of the side orthogonal to each other. Further, in the right-angled triangular prepreg, the orientation direction of the reinforcing fibers is preferably oriented in the axial direction of the golf club shaft 1.

In the present embodiment, a fiber-reinforced resin layer formed by winding a triangular prepreg having a length within a predetermined range from the small-diameter end portion 11 is provided, and one side of the triangular prepreg is triangular. When a configuration arranged so as to correspond to the small-diameter end portion 11 over the entire length of the prepreg is adopted, the rigidity and strength on the small-diameter end portion 11 side can be secured at a predetermined level or more. As a result, even if the portion having a small outer diameter is long, the same feeling as that of a conventional golf club shaft can be obtained. That is, since the physical characteristics can be made to be responsive without receiving an unreliable feel from the golf club shaft 1, in addition to the above-mentioned visual effect and the effect of reducing aerodynamic resistance, a better feeling is achieved. And performance will be obtained.

In the golf club shaft 1 of the present embodiment, a constant mass is secured while the outer diameter is narrowed. This mass depends on the length of the golf club shaft 1, and is not particularly limited. For example, when the length of the golf club shaft 1 is 1168 mm, the mass may be in the range of 35 to 100 g. As described above, it is preferable from the viewpoint of surely obtaining the effect that the player sensitively senses the state of the head and the hit ball. That is, when the mass of the golf club shaft 1 is at least the lower limit of the above range, sufficient strength can be secured, and when it is at least the upper limit of the above range, a stable swing is possible. Can also be obtained. Further, if the weight is 50 g or more, even if the portion having a small outer diameter is long, the weight is not too light and the swinging is improved.

[Base pipe]
The golf club shaft 1 of the present embodiment includes a raw pipe made of a plurality of fiber reinforced resin layers. This raw tube may further have other configurations as long as the effects of the present embodiment can be exhibited. An example of such another configuration is a design-imparting layer or the like.

In general, the physical characteristics of the raw pipe substantially determine the physical characteristics of the golf club shaft 1.
The raw tube has a plurality of fiber reinforced resin layers. Further, as the other layer, for example, a cured or solidified resin layer containing a metal powder such as tungsten, which is blended for the purpose of adjusting the weight or the strength, may be provided. As will be described later, the number of fiber-reinforced resin layers is preferably two or more because the functions of the golf club shaft are shared and expressed.
In addition to the fiber-reinforced resin layer, the raw tube further includes a resin layer, a weight adjusting layer which is a resin layer containing a metal powder such as tungsten, a resin layer containing a filler other than metal and reinforcing fibers, a resin powder, and the like. May be good.

[Fiber reinforced plastic layer]
The fiber-reinforced resin layer is obtained by cutting a matrix resin composition-impregnated reinforcing fiber base material (prepreg) into an appropriate shape and size in consideration of the orientation direction of the reinforcing fibers, and solidifying after curing or softening. It is a layer to be. In the present embodiment, one layer of prepreg is one layer of fiber reinforced resin. The prepreg is a sheet-like base material containing reinforcing fibers and a matrix resin composition.

(Matrix resin composition)
The matrix resin composition contains a matrix resin. This matrix resin composition may further contain components other than the above-mentioned matrix resin as long as the effects of the present embodiment can be obtained.
The content of the other component in the matrix resin composition can be appropriately determined as long as the effect of containing the other component as well as the effect of the present embodiment can be obtained. Further, such other components may be appropriately determined depending on the type of the matrix resin, and may be one kind or more. Examples of the above-mentioned other components include, for example, a curing agent, a curing aid, a mold release agent, a defoaming agent, an ultraviolet absorber, a filler, and the like.

(Matrix resin)
As the matrix resin used for the fiber reinforced resin layer 2, either a thermoplastic resin or a thermosetting resin may be used, and these may be used in combination.
Since the matrix resin has high physical properties after curing, it is preferably used so that the thermosetting resin is the main component.
The type of thermosetting resin is not particularly limited, but an epoxy resin is usually used. Examples of such epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidylamine type epoxy resin, and isocyanate modified epoxy resin. , Or an alicyclic epoxy resin and the like.

The above-mentioned epoxy resin can be used from a liquid one to a solid one without any particular limitation. Further, it is also possible to use a single type of epoxy resin or a blend of two or more types of epoxy resins. Further, it is more preferable to use a curing agent in combination with the epoxy resin.

(Reinforcing fiber)
In the present invention, examples of the reinforcing fibers used in the fiber-reinforced resin layer 2 include metal fibers, boron fibers, carbon fibers, glass fibers, ceramic fibers and other inorganic fibers, aramid fibers, and other high-strength synthetic fibers. Can be mentioned. Inorganic fibers are preferably used because they are lightweight and have high strength. Among these, carbon fibers are more preferable from the viewpoint of excellent specific strength and specific rigidity, and polyacrylonitrile-based carbon fibers are most preferable because they can form a fiber-reinforced plastic layer having excellent mechanical properties. As the reinforcing fibers used in the fiber-reinforced resin layer 2, a single type of reinforcing fibers may be used, or two or more types of reinforcing fibers may be used in combination.

(Reinforcing fiber diameter)
The reinforcing fiber diameter is preferably 3 to 100 μm. The "reinforcing fiber diameter" in the present embodiment means the diameter equivalent to an equal area circle in the cross section of each reinforcing fiber.

In particular, when the reinforcing fiber is a carbon fiber, the reinforcing fiber diameter is preferably 1 μm or more, and more preferably 3 μm or more, from the viewpoint of productivity. Further, in the above case, the reinforcing fiber diameter is preferably 20 μm or less, more preferably 12 μm or less, and further preferably 10 μm or less from the viewpoint of strength.

By setting the reinforcing fiber diameter to be equal to or less than the upper limit of the above range, the tensile strength and the tensile elastic modulus can be increased. Further, by setting the thickness of the reinforcing fiber to the lower limit value or more in the above range, the productivity of the reinforcing fiber can be increased and the manufacturing cost can be reduced.

(Strength and elastic modulus of reinforcing fibers)
The strength of the reinforcing fiber depends on the part of the shaft for the golf club used, but in the case of carbon fiber, the tensile strength (of the resin composition described above) of the strand conforming to JIS R 7608 (2007) is preferably 1000 MPa. The above is preferable. Further, the tensile elastic modulus of the reinforcing fiber is preferably 45 GPa or more for the same reason.

(Length of reinforcing fiber)
The length of the reinforcing fiber is not particularly limited.
For example, fibers of any length such as long fibers, short fibers and mixed fibers thereof may be used as the reinforcing fibers. Further, as the reinforcing fiber, two or more kinds of reinforcing fibers having different lengths may be mixed and used. In the present embodiment, from the viewpoint of increasing the strength of the resin molded product, it is preferable to use long fibers as the reinforcing fibers.

(Form of reinforcing fiber)
In the resin layer, the reinforcing fibers may be a unidirectional material (a material in which the fibers are aligned in one direction) or a cloth material obtained by weaving the reinforcing fibers into a woven fabric.

The unidirectional material is suitable from the viewpoint of fully utilizing the physical properties of the reinforcing fiber such as strength or elastic modulus in the orientation direction of the reinforcing fiber. Further, the unidirectional material is excellent in drapeability in the direction orthogonal to the reinforcing fiber. Therefore, when the shaft for a golf club is manufactured by the seat wrap method described later, the resin layer is easily wound around the mandrel described later, and the handleability is good.

The cloth material can be mainly used to impart design to the outermost surface of the golf club shaft. The cloth material may be a cloth material having any weave structure such as a unidirectional woven fabric such as a bamboo blind weave, a bidirectional woven fabric such as a plain weave, a satin weave, and a twill weave, a triaxial woven fabric, and a non-crimp woven fabric. Among these, bidirectional woven fabrics and triaxial woven fabrics are preferable from the viewpoint of design. Further, the triaxial woven fabric is preferable from the viewpoint of increasing durability.

The fiber texture, resin content, etc. in the plurality of fiber-reinforced resin layers 2 are not particularly limited and can be appropriately selected depending on, for example, the required thickness and winding diameter of each layer, but the volume content of the reinforcing fibers in the resin layer is From the viewpoint of sufficiently increasing the rigidity of the golf club shaft, it is preferably 60% by volume or more, and more preferably 65% by volume or more. Further, the volume content is preferably 75% by volume or less, preferably 70% by volume or less, because a certain amount of resin is required for the matrix resin and the reinforcing fibers to be sufficiently adhered to each other. More preferably.

(Orientation angle of reinforcing fibers)
The orientation direction of the reinforcing fibers in the resin layer can be appropriately determined according to the physical properties to be developed on the golf club shaft, for example, in the same manner as in the invention described in Patent Document 1 described above. The resin layer can be a plurality of layers according to the orientation direction. Examples of such a resin layer include a straight layer, a hoop layer, an angle layer and a bias layer.

(Straight layer)
The straight layer is a resin layer containing reinforcing fibers oriented substantially parallel to the axial direction of the golf club shaft. The straight layer is, for example, a resin layer in which reinforcing fibers of a unidirectional material are oriented at an orientation angle of −5 ° to + 5 ° with respect to the axial direction of a golf club shaft. Further, since the reinforcing fibers of the straight layer are oriented substantially parallel to the longitudinal direction of the golf club shaft, the bending rigidity or bending strength of the golf club shaft can be increased.

The tensile elastic modulus of the reinforcing fiber in the straight layer is preferably 50 GPa or more and 400 GPa or less. When the tensile elastic modulus of the reinforcing fiber is 50 GPa or more, the bending rigidity becomes sufficient. On the other hand, when the reinforcing fiber is a carbon fiber, the strength and the elastic modulus are generally in a trade-off relationship. Therefore, if the tensile elastic modulus of the reinforcing fiber is 400 GPa or less, sufficient strength can be secured.

The thickness of the straight layer as a single layer is preferably 0.050 mm or more and 0.500 mm or less, and more preferably 0.075 mm or more and 0.150 mm or less.
If the thickness of the straight layer is equal to or greater than the lower limit of the above range, the number of laminated resin layers does not become too large, so that the productivity of the golf club shaft may increase. Further, since the handleability of the straight layer is improved, defects such as wrinkles in the straight layer are less likely to occur, and the moldability may be improved.
Further, if the thickness of the straight layer is not more than the upper limit of the above range, the outer diameter or flexural rigidity of the golf club shaft can be made uniform, so that the quality of the manufactured golf club shaft can be improved. Is preferable.

(Hoop layer)
The hoop layer is a resin layer in which the orientation angle of the reinforcing fibers of the unidirectional material is 85 to 95 ° with respect to the longitudinal direction of the golf club shaft. It is preferable to provide the hoop layer mainly from the viewpoint of sufficiently increasing the crushing rigidity and the crushing strength of the golf club shaft. The crushing rigidity is the rigidity in the direction of crushing the tubular structure of the golf club shaft, and the crushing strength is the strength in the direction of crushing the tubular structure of the golf club shaft.

The tensile elastic modulus of the reinforcing fibers in the hoop layer is preferably 240 GPa or more and 400 GPa or less. When the tensile elastic modulus is 240 GPa or more, the crushing rigidity of the golf club shaft can be sufficiently ensured. Therefore, the swing rhythm is less likely to be disturbed due to the crushing deformation of the golf club shaft. On the other hand, it is preferable that the tensile elastic modulus of the reinforcing fiber is 400 GPa or less from the viewpoint of material cost.

The thickness of the hoop layer as a single layer is preferably 0.02 mm or more and 0.100 mm or less.
When the thickness of the hoop layer is 0.02 mm or more, sufficient crushing rigidity can be obtained.
Further, when the thickness of the hoop layer is 0.100 mm or less, the handleability of the hoop layer is improved, the occurrence of wrinkles and the like in the hoop layer is suppressed, and the moldability may be improved.

(Angle layer)
The angle layer is a resin layer in which the absolute value of the orientation angle of the reinforcing fibers of the unidirectional material with respect to the longitudinal direction of the golf club shaft is 20 to 70 °. Assuming that the absolute value of the orientation angle of the reinforcing fibers in the angle layer with respect to the longitudinal direction is α, α is 20 to 70 °, preferably 30 to 60 °, and more preferably 35 to 55 °. It is preferable that α is within the above range from the viewpoint of sufficiently increasing the torsional rigidity, bending rigidity and crushing rigidity of the golf club shaft.

The tensile elastic modulus of the reinforcing fiber in the angle layer is preferably 240 GPa or more and 550 GPa or less. When the tensile elastic modulus is 240 GPa or more, the directionality of the hit ball is good from the viewpoint of sufficiently increasing the torsional rigidity of the golf club shaft and from the viewpoint of preventing the return of the head face at the time of ball impact from being delayed. It is preferable from the viewpoint of Further, it is preferable that the tensile elastic modulus is 550 GPa or less from the viewpoint of sufficiently ensuring the thread cutting strength of the golf club shaft.

The thickness of the angle layer as a single layer is preferably 0.020 mm or more and 0.150 mm or less, and more preferably 0.050 mm or more and 0.125 mm or less.
When the thickness of the angle layer is equal to or greater than the lower limit of the above range, the number of laminated resin layers does not become too large, so that the occurrence of wrinkles and the like in the resin layer is suppressed, and the moldability can be improved. ..
It is preferable that the thickness of the angle layer is not more than the upper limit of the above range from the viewpoint of making the outer diameter or flexural rigidity of the golf club shaft uniform.

(Bias layer)
The bias layer is a layer containing a pair of angle layers having positive and negative α. The bias layer is an angle layer (+ α layer) containing reinforcing fibers oriented at a positive orientation angle + α with respect to the longitudinal direction of the golf club shaft, and an angle containing reinforcing fibers oriented at a negative orientation angle −α. Contains a layer (-α layer). It is preferable to provide a bias layer mainly from the viewpoint of increasing the torsional rigidity or the torsional strength of the golf club shaft.

It is desirable that the + α layer and the −α layer constituting the bias layer are substantially offset by half a circumference and bonded together. When the + α layer and the −α layer are staggered and bonded together, the anisotropy can be reduced because the unevenness of the winding end portion does not increase. Further, it is preferable to attach the + α layer and the −α layer in a staggered manner from the viewpoint of preventing problems such as poor appearance or decrease in strength of the golf club shaft.

(Other resin layers)
The golf club shaft of the present embodiment may further include a resin layer other than the above-mentioned resin layer as long as the effect of the present embodiment can be obtained. Examples of such other layers include a partial bias layer and a partial straight reinforcement layer. It is preferable to provide such a partial layer from the viewpoint of partially controlling the torsional rigidity or flexural rigidity of the golf club shaft.
The tensile elastic modulus of the reinforcing fiber in the other resin layer and the thickness of the other resin layer in a single layer can be appropriately determined from the above ranges according to the function.

In the golf club shaft of the present embodiment, it is preferable that at least one of the plurality of fiber-reinforced resin layers 2 contains reinforcing fibers having an elastic modulus of 280 GPa or more in the entire length. The elastic modulus of the reinforcing fiber is preferably 280 GPa or more, more preferably 300 GPa or more, and further preferably 320 GPa or more. When the reinforcing fiber is a carbon fiber, the elastic modulus is preferably 500 GPa or less, more preferably 450 GPa or less, still more preferably 400 GPa or less. When the elastic modulus of the reinforcing fiber is at least the lower limit value in the above range, sufficient rigidity can be ensured even if the outer diameter of the golf club shaft is small. Further, when the reinforcing fiber is a carbon fiber, the strength and the elastic modulus are generally in a trade-off relationship. Therefore, if the elastic modulus of the reinforcing fiber is equal to or less than the upper limit of the above range, the shaft for a golf club Sufficient strength can be ensured, and handleability is improved even during manufacturing.
In the present embodiment, any one of the plurality of fiber-reinforced resin layers 2 contains the above-mentioned reinforcing fibers, so that the portion having a very small outer diameter is extremely small while ensuring the rigidity as a shaft for a golf club. A long golf club shaft 1 is obtained.

In the golf club shaft of the present embodiment, at least one layer of the plurality of fiber reinforced resin layers 2 includes, as reinforcing fibers, reinforcing fibers having an elastic modulus of 280 GPa or more and a tensile strength of 5500 MPa or more in the entire length. Is preferable.
The elastic modulus of the reinforcing fiber is preferably 280 GPa or more, more preferably 300 GPa or more, and further preferably 320 GPa or more. When the reinforcing fiber is carbon fiber, it is preferably 500 GPa or less, more preferably 450 GPa or less, and further preferably 400 GPa or less.
If the elastic modulus of the reinforcing fiber is equal to or higher than the lower limit of the above range, sufficient rigidity can be secured even if the outer diameter of the golf club shaft is long, so that the strength can be increased by suppressing deformation during swing. Have enough. Further, by having an appropriate degree of bending, it is possible to obtain a golf club shaft 1 which is excellent in operability and is preferred by a wide range of players. Further, when the reinforcing fiber is carbon fiber, the strength and the elastic modulus are generally in a trade-off relationship. Therefore, if the reinforcing fiber is not more than the upper limit of the above range, the strength of the golf club shaft can be sufficiently secured. , The handleability is improved even at the time of manufacturing.
The strength of the reinforcing fiber is preferably 5500 MPa or more, more preferably 6000 MPa or more, further preferably 6500 MPa or more, and particularly preferably 6700 MPa or more. When the strength of the reinforcing fiber is at least the lower limit value in the above range, sufficient strength can be ensured even if the outer diameter of the golf club shaft is small.
In the present embodiment, since any one of the plurality of fiber-reinforced resin layers 2 contains the above-mentioned reinforcing fibers, sufficient rigidity and strength as a shaft for golf clubs are secured even if the outer shape is thin. can.

In the present embodiment, when any one of the plurality of fiber-reinforced resin layers 2 contains reinforcing fibers having an elastic modulus of 280 to 500 GPa, the reinforcing fibers are particularly preferably carbon fibers.
Further, the reinforcing fiber resin layer containing the reinforcing fibers as described above is more preferably a plurality of layers.

Further, in the present embodiment, when any layer of the plurality of fiber reinforced resin layers 2 contains reinforcing fibers having the elastic modulus and tensile strength in the above range, the reinforcement is reinforced from the viewpoint that the above-mentioned effects can be remarkably obtained. The fiber-reinforced resin layer containing fibers preferably has a reinforcing fiber content in the range of ^{75 to 150 g / m 2.}

[Design-imparting layer]
The design-imparting layer is usually a layer constituting the surface of a golf club shaft, and plays a role of decoration for displaying a pattern, a color, a brand name, or the like. By having a design-imparting layer, it is possible to improve the design and increase the purchasing motivation of consumers. It is also preferable from the viewpoint of increasing the favorability of female golfers. The design imparting layer may be arranged over the entire length of the golf club shaft, or may be arranged on a part of the golf club shaft in the longitudinal direction.

The design imparting layer may be composed of only the surface layer, or may be composed of a plurality of layers including the surface layer. For example, the design-imparting layer can be all layers formed on the outer surface of the golf club shaft before the design-imparting layer is manufactured.
The design-imparting layer can be produced by a known method. In this case, for example, the design-imparting layer is provided with an undercoat layer, an intermediate coat layer, or the like, and then decorated with a decorative layer to form an overcoat layer made of a transparent or translucent paint on the surface thereof. Can be manufactured. Alternatively, the design-imparting layer can be produced, for example, by a method of decorating with a colored spray coat.

The film thickness of the design-imparting layer as described above is not particularly limited, but is preferably 0.05 to 0.1 mm.

The material of the design-imparting layer (for example, the above-mentioned decorative layer) can be appropriately selected from known materials within a range in which a desired design can be expressed, for example, in a range in which aesthetics can be improved. Examples of the material include ink, metal foil and the like.
The materials of various layers such as the overcoat layer, the undercoat layer, and the intermediate coat layer described above have high adhesion to the adjacent layers, and the intended use in each layer (for example, the overcoat layer is damaged). It can be appropriately selected from known materials as long as it can be used for the purpose of a protective coating for preventing the above.

[Various characteristics of golf club shafts]
It is more preferable that the various characteristics described below of the golf club shaft 1 of the present embodiment are in the optimum range.

(Flexural rigidity EI)
In the golf club shaft 1 of the present embodiment, the flexural rigidity EI (× 10 ⁶ kgf-mm ² ) at a position 100 to 300 mm from the small diameter end portion 11 is 1.5 (× 10 ⁶ kgf-mm ² ) or more. It is preferably 4.0 (× 10 ⁶ kgf-mm ² ) or less. When the flexural rigidity EI satisfies the above range, it becomes the bending rigidity value of the golf club shaft required for a player with high skill and a player with a high swing speed.

If it is less than the flexural rigidity EI position 100~300mm small-diameter end portion 11 is ^{1.5 (× 10 6 kgf-mm} 2), since the head is returned late at impact, the swing is not stabilized, hitting The direction of is unstable. Further, when the flexural rigidity EI position 100~300mm small-diameter end portion 11 is greater than ^{4.0 (× 10 6 kgf-mm} 2), does not take proper spin to the ball, hitting becomes low, Fei The distance may decrease.

The flexural rigidity EI of the golf club shaft is a three-point bending test method for the C-shaped shaft in the "certification standard and standard confirmation method for the golf club shaft" defined by the Product Safety Association, as described in Examples described later. Can be measured with.

(torque)
In the golf club shaft 1 of the present embodiment, it is preferable that the torque is 4 ° or more and 12 ° or less from the viewpoint of stabilizing the direction of the hit ball.
If the torque is less than 4 °, the number of layers of the bias layer (not shown) constituting the fiber reinforced resin layer 2 increases and the weight becomes heavy, which causes a decrease in the flight distance of the hit ball due to a decrease in the head speed during the swing. Tends to be. Further, when the torque exceeds 12 °, the weight of the golf club shaft can be reduced, but the strength tends to be insufficient and the direction of the hit ball tends to be unstable.
Further, from the above viewpoint, the torque is more preferably 4 ° or more and 10 ° or less.

The "torque" described in the present invention means that the small-diameter end portion 11 and the large-diameter end portion 12 of the golf club shaft 1 are clamped by chucks, and the torsion torque (1) is applied to the golf club shaft via the chucks. This is the twist angle when .36 Nm) is added.

(Kick point)
In the golf club shaft 1 of the present embodiment, the kick point is preferably in the range of 40% or more and 48% or less.
If the kick point is less than 40%, the direction of the hit ball tends to be unstable. In addition, when the kick point exceeds 48%, it tends to be difficult to hit the ball and it is difficult to use it.
From the above viewpoint, the kick point is more preferably in the range of 41% or more and 47% or less, and further preferably in the range of 42% or more and 46% or less.

Here, the "kick point" described in the present invention is a small diameter end from the peak point when compression bending deformation is performed in the longitudinal axis direction from the small diameter end side and the large diameter end side of the golf club shaft. The distance to the portion is expressed as a ratio to the total length of the golf club shaft, and can be measured by the method described in Examples described later.

(Balance point)
In the golf club shaft 1 of the present embodiment, it is preferable that the balance point in the longitudinal axis direction is 54% or more from the small diameter end portion 11. When the balance point is at a position of 54% or more from the small diameter end portion 11, excellent stability as a shaft for a golf club can be obtained. If the balance point is outside the above range, that is, if the balance point is located closer to the large diameter end portion 12, even if the head weight is increased for the purpose of improving the flight distance, the weight will be increased during the swing. Since it is easy to feel, the ease of swinging the golf club is reduced, and the ball speed tends to be difficult to increase.

Here, the "balance point" described in the present invention means a support point capable of keeping the golf club shaft in a horizontal state when one point in the longitudinal axis direction of the golf club shaft is supported. ..
Further, the balance point of the golf club shaft according to the present invention is the position and size of the mass / outer diameter adjusting layer contained in the plurality of fiber-reinforced resin layers 2 in the longitudinal axis direction of the golf club shaft as described above. Now, it can be optimized by adjusting the type.

The balance point is more preferably at a position of 50% or more from the small diameter end portion 11, further preferably at a position of 52% or more, and most preferably at a position of 53% or more. However, in order to increase the balance point, it is necessary to reduce the number of layers of the fiber reinforced resin layer 2 on the small diameter end portion 11 side and to form the fiber reinforced resin layer 2 in a lightweight manner. , There is a possibility that breakage may occur due to insufficient strength of the small diameter end portion 11. From this point of view, the balance point is more preferably 62% or less, further preferably 61% or less, and most preferably 60% or less.

<Manufacturing method of golf club shaft>
The method for manufacturing a golf club shaft according to the present invention is the method for manufacturing the golf club shaft 1 of the present embodiment as described above.
The shaft for a golf club according to the present invention is manufactured by manufacturing a raw pipe and, if necessary, forming a design-imparting layer on the raw pipe. When the design-imparting layer is not formed on the raw pipe, the raw pipe corresponds to the golf club shaft 1 of the present embodiment. In addition, the shaft 1 for a golf club may be obtained by applying wax or the like to the raw tube to enhance the appearance.

As a method for manufacturing a shaft for a golf club of the present embodiment, for example, a plurality of prepregs are wound around a mandrel, heated, cooled, and then withdrawn from the mandrel to form a plurality of hardened or solidified fiber-reinforced resin layers. A so-called seat wrapping method for obtaining a shaft for a golf club having a golf club can be mentioned.

In the above sheet wrapping method, a plurality of types of prepregs having different types, areas, or orientation angles of the reinforcing fibers are prepared, and these prepregs are sequentially wound around a mandrel one by one or as a set of a plurality of prepregs to multiple layers. The procedure for manufacturing a shaft for a golf club having a structure is common. In this case, the number of prepregs is not particularly limited, but is generally about 8 to 14.

In the present embodiment, the area and shape of each prepreg, the orientation angle of the reinforcing fibers, the tensile elastic modulus of the reinforcing fibers, the position where the prepreg is wound in the mandrel, the number of prepregs (the number of layers of the fiber reinforced resin layer), and the mandrel. Adjust the shape of the Thereby, the golf club shaft of the present embodiment in which the taper degree of the golf club shaft, the outer diameter of the golf club shaft, and the various physical properties described above are desired specifications can be manufactured.

That is, the manufacturing method of the present embodiment is a method including at least a winding step of forming a plurality of fiber reinforced resin layers 2 by winding a plurality of prepregs around the mandrel 30 as shown in FIG. ..
In the above winding step, a mandrel 30 having a small diameter end portion 31 having a small outer diameter in the vicinity of one end side and a large diameter end portion 32 having a large outer diameter in the vicinity of the other end side is used.

In the method for manufacturing the golf club shaft 1 of the present embodiment, the mandrel 30 as described above is used, and a plurality of prepregs having each pattern shown in FIG. 9 are sequentially wound around the mandrel 30 and laminated. Next, a heat-shrinkable tape is wrapped around the prepreg at a predetermined pitch, the above-mentioned laminate is fixed, and then the prepreg is cured or solidified and molded by heating and then cooling. Then, after removing the heat-shrinkable tape, the surface is polished to obtain a raw tube.

According to the method for manufacturing the golf club shaft 1 of the present embodiment, since there is no portion where the outer diameter of the obtained golf club shaft 1 changes significantly in the longitudinal axis direction, it becomes easy to polish the raw pipe. Therefore, it becomes possible to manufacture the shaft 1 for golf clubs, which is excellent in handleability and strength characteristics, with high productivity.

In the above winding step, the length of the golf club shaft in the longitudinal axis direction is {L1 / 3-150 mm or more} above the winding start position in the mandrel of the prepreg, which is triangular in plan view. , {L1 / 3 + 150 mm} or less, and wound directly on the mandrel, or wound on the prepreg wound on the mandrel, among the plurality of fiber reinforced resin layers. Form at least one layer.

The above-mentioned prepreg that is triangular in plan view is more preferably a right triangle. Further, one of the two sides of the right triangle that is orthogonal to each other is arranged at the small diameter end portion 11 so as to be orthogonal to the axial direction of the golf club shaft (FIG. FIG. See the column for pattern 8 in 9.). Further, of the two orthogonal sides in the prepreg of a right triangle, the other side is arranged and wound so as to correspond to the axial direction of the golf club shaft over the entire length of the one side.

In the right-angled triangular prepreg, it is preferable that one of the two sides orthogonal to each other is shorter than the other, and the side arranged at the small-diameter end portion 11 is the short side of the side orthogonal to each other. Further, it is preferable that the orientation direction of the reinforcing fibers is oriented in the axial direction of the golf club shaft.

[Golf club]
A golf club to which the golf club shaft according to the present invention is applied is usually assembled by attaching a head to the tip end of the shaft and attaching a grip to the bat end, although detailed illustration is omitted. To exemplify a golf club for wood, usually, both ends of the golf club shaft 1 are cut and the total length of the shaft is adjusted to 1100 mm to 1130 mm in order to have a conventional length of 42 inch to 46 inch as a club. Then attach the head and assemble. Here, when the golf club shaft according to the present invention is applied to an iron or a hybrid, the club length is adjusted to be 32 to 42 inches. As described above, the golf club shaft 1 is generally used after cutting both ends when assembling to the golf club at the time of manufacturing, but the golf club shaft 1 of the present invention is used both before and after cutting. Shall mean.

<Effect>
As described above, according to the golf club shaft 1 of the present embodiment, as described above, the outer diameter D1 in the range from the small diameter end portion 11 to at least the position A of 1/3 of the total length L1 is set. The shape is optimized by making it constant and 6 mm or more and 10 mm or less, and setting the outer diameter D2 of the large diameter end portion 12 to 13 mm or more and 15 mm or less. As described above, as compared with the conventional golf club shaft, the outer diameter is narrowed over a long range of at least 1/3 of the total length of the golf club shaft, so that the heads are relatively close to each other and the head is relatively close to each other. The visual effect that the head looks large and the psychological effect that the head is likely to be easily hit by the golf ball are obtained. In addition, by reducing the aerodynamic resistance, swinging is improved and the head speed during swing is improved. This improves player performance. Further, since there is no portion where the outer diameter changes abruptly, polishing at the time of manufacturing is easy, and the productivity is excellent.
Therefore, it is possible to provide a golf club shaft 1 which is excellent in operability and also excellent in productivity.

Further, according to the method of manufacturing the golf club shaft 1 of the present embodiment, by using the prepreg having the above-mentioned shape, the outer diameter from the small diameter end portion 11 to the position A of 1/3 of the total length L is reached. A golf club shaft 1 having a predetermined thickness and a constant outer diameter D2 of the large diameter end portion 12 can be obtained. This improves productivity when polishing the shaft for golf clubs. That is, the golf club shaft 1 having excellent operability can be manufactured with high productivity.

<Others>
Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations thereof described in the present embodiment are examples, and the configurations are not deviated from the gist of the present invention. Additions, omissions, replacements, and other changes are possible. Further, the present invention is not limited to the present embodiment, but is limited only by the scope of claims.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to these Examples.

<Example 1>
[Manufacturing of shafts for golf clubs]
In Example 1, first, as the mandrel 30, a mandrel 30 made of an iron cylinder as shown in FIG. 9 was used. That is, the outer diameter d1 from this position to the position of 389.3 mm in the longitudinal axis direction is constant at 3.10 mm from the position 20 mm from the end portion 30a (small diameter end portion 31), and further, the above starting point. From to the position of 1190 mm in the longitudinal axis direction, the diameter was gradually increased with a taper rate of 10.22 / 1000, and the outer diameter d2 at the position expanded to this maximum diameter was set to 12.10 mm.

Further, in Example 1, a prepreg (carbon prepreg: manufactured by Mitsubishi Chemical Corporation) having the shape and dimensions shown in FIG. 9 and having the specifications shown in Table 1 below was prepared.

Then, the prepregs (patterns 1 to 9) cut into the pattern shown in FIG. 9 were wound around the outer peripheral surface of the mandrel 30 in order from the pattern 1.
As shown in the corresponding positional relationship in FIG. 9, the patterns 1, 4 to 6 are wound so as to cover the entire length of the golf club shaft 1 after being laminated.
Further, the pattern 2 was wound so as to be arranged only on the large diameter end side.
Further, the patterns 3, 7 to 9 were wound so as to be arranged only on the small diameter end side. Here, the patterns 3, 8 and 9 are triangular prepregs, and one side thereof is arranged and wound so as to correspond to the small diameter end portion over the entire length thereof.

The patterns 1 to 3 include a prepreg that forms an angle layer in which the fiber direction of the carbon fibers (CF) is oriented at + 45 ° with respect to the axial direction of the mandrel, and a prepreg that forms an angle layer that is oriented at −45 °. And two sheets were overlapped with respect to the mandrel 30 so as to be substantially offset by half a circumference.

Further, the region around which the prepreg is wound in the mandrel 30 is set from a position 20 mm from the end portion 30a of the mandrel 30 to a position of 1190 mm.

In this embodiment, the prepreg consisting of the above patterns 1 to 9 was sequentially wound around the mandrel 30. The total mass of each pattern at this time was 69.46 g. Then, a shrinkage tape made of polypropylene having a width of 20 mm was wrapped around the tape at a pitch of 2 mm. Then, in this state, it was introduced into a heating furnace and heated, and kept at 135 ° C. for 2 hours. Next, this was naturally cooled to room temperature, the cured golf club shaft was removed from the mandrel 30, the shrinkage tape was peeled off, and then the surface was polished so that the natural frequency of the golf club shaft was 273 cpm.

Next, the mandrel 30 was pulled out, and the small-diameter end side and the large-diameter end side of the golf club shaft were appropriately cut to set the total length L1 of the raw pipe of the golf club shaft to 1168 mm.
Then, an undercoat was applied onto the obtained raw tube using Shigoki Primer Dark Gray Part No .; 9-7010EP (registered trademark: manufactured by Mikuni Paint), and then Diamond Black Part No .; 519310 (registered trademark: manufactured by TCP) was applied. Using, a design-imparting layer was formed by ironing, and then a protective layer was formed with NY Shigoki Clear product number; 916 (registered trademark: manufactured by Mikuni Paint). The mass after painting at this time was 60.1 g.
According to the above conditions and procedures, a golf club shaft of an example having specifications as shown in Table 2 below was obtained.

In the obtained golf club shaft of Example 1, the outer diameter D1 of the small-diameter end portion at the tip is 8.51 mm (position 10 mm from the small-diameter end portion), and the outer diameter of the large-diameter end portion at the rear end. D2 was 14.88 mm (25 mm from the large diameter end).
Further, in the golf club shaft of Example 1, the outer diameter D1 (mm) in the range from the small diameter end to the position A of 389.3 mm was constant at 8.51 mm.
Further, as shown in the graph of FIG. 12, the golf club shaft of the first embodiment has a tapered shape having a constant taper ratio between the position B and the position A 300 mm from the large diameter end portion. In the example, the range from the position A to the large-diameter end was a tapered shape with a substantially constant taper ratio.

In all the examples and comparative examples described below, the dimensions of the golf club shaft in the longitudinal axis direction are all based on the configuration after cutting.

[Evaluation of golf club shafts]
The evaluation test using the sample of the golf club shaft carried out in this example will be described below.

(Measurement of flexural rigidity EI)
In this example, the test was carried out according to the three-point bending test method of the C-shaped shaft in the "certification standard and standard confirmation method of the golf club shaft" defined by the Product Safety Association. That is, in this embodiment, the three-point bending test device 40 as shown in FIG. 3 is used, and the pair of left and right support portions 46, the load portion 42, and the load measurement portion 43 arranged at intervals of 150 mm are used. A golf club shaft was set so that a point (load point position) 90 mm from the small diameter end portion 11 (see FIG. 1 and the like) was directly below the load portion 42, and a three-point bending test was performed. .. The load speed in this measurement was set to 20 mm / min, and in order to prevent crushing at the load point, a test was conducted via a silicon rubber having a thickness of 2 mm and 70 HSD.

The amount of displacement of the golf club shaft 1 due to the load is defined as the flexural rigidity EI, and the relationship between the flexural rigidity EI and the distance from the small-diameter end portion 11 of the golf club shaft 1 is shown in the graph of FIG. ..

(Measurement of balance point)
As shown in the schematic view of FIG. 4, a support point capable of keeping the golf club shaft 1 in a horizontal state in a state where the golf club shaft 1 is balanced on the fulcrum 50 and one point in the longitudinal axis direction is supported is provided. indexing, and measure the distance L _G between this position and the small diameter end portion 11. Then, those shown by the ratio between the distance L _G and the overall length L1 and balance point Bp, the results are shown in Table 2 below.

(Measurement of kick point)
The kick point was determined by the method described in Japanese Patent Application Laid-Open No. 10-225541.
That is, in this embodiment, a kick point gauge FG-105RM (manufactured by FOURTEEN Co., Ltd.) is used as a measuring device, and as shown in the schematic view of FIG. 5, the small diameter end portion 11 and the large diameter of the golf club shaft 1 are used. A load P was applied from both ends 12 to measure the kick point. In this case, the determined kick point position Kp (the length L _K of the small-diameter end portion _11), expressed as a percentage of the total length L1 of the golf club shaft 1 and the results are shown in Table 2 ..

(Measurement of cantilever bending displacement)
As shown in FIG. 6, the position of the golf club shaft 1 from the small diameter end portion 11 to 920 mm is supported from the lower side, and the position 150 mm in the large diameter end portion 12 side direction from that position (from the small diameter end portion 12). The position of 1070 mm) was supported from above, and a load of 3.0 kgf was applied to a position of 10 mm from the small diameter end 11 side. The displacement amount of the small diameter end portion 11 at this time was defined as the "cantilever bending displacement amount (mm)", and the results are shown in Table 2 below.
In this example, in the case where the displacement amount becomes too large with a load of 3.0 kgf and measurement is difficult, the load is set to 1/3 (1.0 kgf) or 1/2 (1.5 kgf). In this case, the value obtained by multiplying the measured displacements by 1/3 or 1/2 was defined as the "cantilever bending displacement amount (mm)".

(Measurement of frequency)
The frequency was measured by the method described in JP-A No. 10-225541.
That is, in this embodiment, a golf club timing harmonizer (manufactured by Fujikura Rubber Co., Ltd.) is used as a measuring device, and as shown in FIG. 7, a mass imitating a head is formed on the small diameter end portion 11 of the golf club shaft 1. A 196 g weight 60 was attached, and a position 180 mm from the large diameter end portion 12 was fixed to the fixed portion 61 to obtain the natural frequency of the golf club shaft 1.

(Measurement of torque (twist angle of the entire shaft))
The torque, that is, the twist angle of the entire golf club shaft was measured according to the method for measuring the torque (twist angle of the entire golf club shaft) described in Japanese Patent Application Laid-Open No. 5-337223.
That is, first, while adjusting the dimensional relationship shown in FIG. 8, the small diameter end portion 11 side was clamped by the chuck 71, and the large diameter end portion 12 side was clamped by the chuck 72.
Then, a torsion torque (1.36 Nm) was applied to the chuck 71 clamped to the small diameter end portion 11 side, and the torsion angle at this time was measured, and the results are shown in Table 2 below.

(Measurement results for each evaluation item)
Each of the length, mass, outer diameter on the small diameter end side, outer diameter on the large diameter end side, frequency, cantilever bending displacement, torque, balance point, and kick point of the golf club shaft 1 of the present embodiment. Is shown in Table 2 below. The values shown in Table 2 are average values of golf club shafts manufactured with n = 2. Further, in Table 2, the measurement results of Comparative Examples 1 and 2 described below are also shown.

<Comparative example 1>
In Comparative Example 1, a mandrel and a prepreg were selected to produce a base tube for a golf club shaft so as to have an outer diameter described in US Patent Publication: US10272304. Then, the design-imparting layer was applied in the same manner as in Example 1 to obtain a golf club shaft of Comparative Example 1 having specifications as shown in Table 2 above.
In the obtained golf club shaft of Comparative Example 1, the outer diameter D1 of the small-diameter end portion at the tip is 8.03 mm (position 10 mm from the small-diameter end portion), and the outer diameter of the large-diameter end portion at the rear end. D2 was 15.33 mm (25 mm from the large diameter end).
The golf club shaft of Comparative Example 1 had an outer diameter D1 (mm) in the range from the small diameter end to a position of 100 mm, which was approximately constant at 8.03 mm to 8.09 mm.
Further, as shown in the graph of FIG. 12, the golf club shaft of Comparative Example 1 has a random taper ratio between the position B 300 mm from the large diameter end and the position 100 mm from the small diameter end. It had a tapered shape.

Then, in Comparative Example 1, the same evaluation items as in Example 1 were measured, and the measurement results are shown in Table 2 above.

<Comparative example 2>
In Comparative Example 2, a raw pipe of a shaft for a golf club was produced according to Example 1 described in JP-A-2014-061277. Specifically, the mandrel 130 is made of an iron cylindrical body as shown in FIG. 10, starting from a position 80 mm from the end portion 30a (small diameter end portion 131), and the outer diameter d1 at this position is 4. It is .09 mm, and the outer diameter d1 from this position to the position of 120 mm in the longitudinal axis direction changes as shown in the figure, and further, from the above starting point to the position of 1190 mm in the longitudinal axis direction is 8.01 / 1000. The diameter was gradually increased at the taper rate, and the outer diameter d2 at the position (large diameter end) expanded to this maximum diameter was 13.90 mm.

Further, in Comparative Example 2, a prepreg (manufactured by Mitsubishi Chemical Corporation) made of a fiber reinforced resin having the shape and dimensions shown in FIG. 10 and having the specifications shown in Table 3 below was prepared.

Then, as in the case of Example 1 and Comparative Example 1, the prepregs (patterns 1 to 11) cut into the pattern shown in FIG. 10 were wound around the outer peripheral surface of the mandrel 130 in order from the pattern 1. The total mass of each pattern at this time was 74.41 g.
The patterns 3 to 5, 7 to 9 were wound so as to cover the entire length of the golf club shaft after laminating.
Further, the pattern 2 was wound so as to be arranged only on the large diameter end side.
Further, the patterns 1, 6, 10 and 11 were wound so as to be arranged only on the small diameter end side.

As patterns 3, 4 and 6, a prepreg forming an angle layer in which the fiber direction of the carbon fiber (CF) is oriented at + 45 ° with respect to the axial direction of the mandrel and an angle layer oriented at −45 ° are formed. Two prepregs to be used were overlapped with each other so as to be substantially offset by half a circumference with respect to the mandrel 130.

Further, the region around which the prepreg is wound in the mandrel 130 is set from the small diameter end 131 arranged at a position 80 mm from the end 130a of the mandrel 130 to the position 1190 mm toward the large diameter end 132.

In Comparative Example 2, a prepreg composed of the above patterns 1 to 15 was sequentially wound around the mandrel 130, and then a 20 mm wide polypropylene heat-shrinkable tape was wound around the mandrel 130 at a pitch of 2 mm, and the prepreg was introduced into a heating furnace in this state. It was warmed and kept at 135 ° C. for 2 hours. Next, this was naturally cooled to room temperature, the cured golf club shaft was removed from the mandrel 130, the heat-shrinkable tape was peeled off, and then the surface was polished so that the natural frequency of the golf club shaft was 275 cpm.

Next, the mandrel 130 is pulled out to appropriately cut the small-diameter end side and the large-diameter end side of the golf club shaft, and further, by polishing this cut portion, the total length L1 of the golf club shaft is set to 1168 mm. bottom.
According to the above conditions and procedures, a golf club shaft of Comparative Example 2 having specifications as shown in Table 2 above was obtained.
In the obtained golf club shaft of Comparative Example 2, the outer diameter D1 of the small-diameter end portion at the tip is 8.51 mm (position 10 mm from the small-diameter end portion) and 8.50 mm (75 mm from the small-diameter end portion). Position). Further, the outer diameter D2 of the large-diameter end portion, which is the rear end, was 15.91 mm (position 25 mm from the large-diameter end portion).
As shown in the graph of FIG. 12, the golf club shaft of Comparative Example 2 has an outer diameter D1 (mm) in a range from a position 120 mm from the small diameter end to a position A of 389.3 mm. It had a slightly tapered shape that was not constant within the range of the length of.
Further, the golf club shaft of Comparative Example 2 had an outer diameter D2 (mm) of a large diameter end portion of 15.91 mm.
Further, as shown in the graph of FIG. 12, the golf club shaft of Comparative Example 2 had a tapered shape having a constant taper ratio between the position B and the position A 300 mm from the large diameter end portion.

Then, in Comparative Example 2, the same evaluation items as in Example 1 and Comparative Example 1 were measured, and the measurement results are shown in Table 2 above.

<Evaluation result>
As shown in Table 2 above, the outer diameter D1 (mm) in the range from the small diameter end 11 to the position A of 389.3 mm in the longitudinal axis direction is 8 with respect to the length L1 (mm) of the golf club shaft 1. The golf club shaft 1 of the first embodiment, which is constant at .51 mm and has an outer diameter D2 (mm) on the large diameter end 12 side of 14.88 mm, satisfies all the provisions of the present invention. According to the golf club shaft of the first embodiment, by having the above-mentioned structure and dimensions, the outer diameter D1 (mm) and the outer diameter D2 (mm) are not too thin, and the conventional shaft is used over the entire length. It is made thinner than the shaft for golf clubs. As a result, the head looks larger than the shaft for the golf club, so that the psychological effect that the head is likely to hit the ball well is obtained. In addition, it was found that the head speed is increased because the air resistance is reduced because the outer diameter is small as a whole. Therefore, it can be seen that excellent feeling and performance can be obtained. Further, since the small-diameter end portion and the large-diameter end portion in Example 1 had the same dimensions as the conventional golf club shaft, a commercially available head and grip could be attached.

Further, the golf club shaft 1 of the first embodiment has a smaller outer diameter over the entire length, a narrower diameter end portion 11 side, and further, the vicinity of the middle portion in the longitudinal axis direction is smaller than that of the conventional golf club shaft. Since it has a tapered shape with a constant taper rate, it is thin from the bottom of the grip to the small diameter end side, and the degree of taper is small, so a sense of perspective is generated and the head can be seen close, so it seems easy to swing. A psychological effect was obtained. It was confirmed that by adding such a psychological effect, even better performance can be exhibited. Further, the golf club shaft of the first embodiment has sufficient rigidity, an appropriate rigidity distribution, and a sufficient weight, so that good bending can be obtained at the time of swing and there is a response, so that the head speed can be increased. It turned out to go up.

In the golf club shaft 1 of the first embodiment, among the plurality of fiber-reinforced resin layers 2, the prepregs of the patterns 8 and 9 have a triangular shape in a plan view, and the longitudinal axis of the golf club shaft 1 The length in the direction is {L1 / 3-150 (mm)} or more and {L1 / 3 + 150 (mm)} or less with respect to the length L1 (mm) starting from the small diameter end portion 11. There is. As a result, in particular, the rigidity and strength on the small diameter end 11 side are secured above a predetermined level, and the outer diameter is narrowed while improving the strength and rigidity on the head side. It was confirmed that excellent feeling and performance can be obtained.

On the other hand, in the golf club shaft of Comparative Example 1, the outer diameter D1 (mm) exceeds the upper limit specified in the present invention, so that the effect of reducing air resistance is limited. Further, the golf club shaft of Comparative Example 1 had a portion where the outer diameter changed significantly in the vicinity of a position 100 mm from the small diameter end portion. Therefore, the part where the outer diameter changes greatly is deformed greatly at the time of swing, so especially for players with fast head speeds, there is an impression that the head is not stable, and it is said that it is losing or unreliable. There was a feeling. Therefore, the golf club shaft of Comparative Example 1 is considered to be a characteristic preferred by a very limited number of players.
Further, with respect to the golf club shaft of Comparative Example 2, since the outer diameter is large as a whole and the outer diameter D1 (mm) exceeds the upper limit specified in the present invention, the reduction in air resistance is small. It became inferior in the sense of pulling out.
Therefore, in the golf club shafts of Comparative Example 1 and Comparative Example 2, the psychological effect obtained by having a long portion having a small outer diameter and the swing due to the reduction of air resistance, as in the golf club shaft of Example 1. It became clear that the effects such as the goodness of pulling out were hardly felt.

From the results of the examples described above, by using the shaft for golf clubs according to the present invention, the appearance gives the player a psychological effect that the performance is likely to improve, and the swing is made to reduce the air resistance. It is clear that it has excellent feeling and performance because it improves and the head speed increases.

The shaft for a golf club of the present invention can give a psychological effect to a player, is excellent in feeling and performance, and is also excellent in productivity. Therefore, it is very suitable as a golf club shaft used for golf clubs for drivers, fairways and irons.

1 ... Golf club shaft 11 ... Small diameter end 12 ... Large diameter end 2 ... Fiber reinforced resin layer (prepreg)
A, B, C ... Position (Golf club shaft)
L1 ... Length (Golf club shaft)
D1, D2 ... Outer diameter (golf club shaft)
30 ... Mandrel 31 ... Small diameter end 32 ... Large diameter end a1, b1 ... Position (mandrel)
L2 ... Length (mandrel)
d1, d2 ... Outer diameter (mandrel)

Claims (6)

A shaft for golf clubs in which a plurality of fiber-reinforced resin layers containing reinforcing fibers are laminated.
The golf club shaft has a small diameter end portion having a small outer diameter on one end side and a large diameter end portion having a large outer diameter on the other end side.
When the length of the golf club shaft is L1 (mm), it is represented by at least the following equation {L1 / 3 (mm)} from the small diameter end portion in the longitudinal axis direction of the golf club shaft. The outer diameter D1 (mm) in the range up to the position A is constant at 6 mm or more and 10 mm or less.
A shaft for golf clubs, wherein the outer diameter D2 (mm) of the large diameter end portion is 13 mm or more and 15 mm or less. When the end on the large diameter end side of the portion where the outer diameter D1 (mm) is constant is set to position C,
In the longitudinal axis direction of the golf club shaft, the range between the position B 300 mm from the large diameter end and the position C the position A is tapered, and the taper rate in the range is constant. The shaft for a golf club according to claim 1, wherein the shaft is provided. The golf according to claim 1 or 2, wherein at least one layer of the plurality of fiber-reinforced resin layers contains the reinforcing fibers having an elastic modulus of 280 to 500 GPa over the entire length as the reinforcing fibers. Club shaft. A claim, wherein at least one layer of the plurality of fiber-reinforced resin layers contains, as the reinforcing fiber, a high-strength high-elasticity reinforcing fiber having an elastic modulus of 280 to 500 GPa and a tensile strength of 5500 to 8500 MPa. The shaft for a golf club according to any one of 1 to 3. At least one of the plurality of fiber-reinforced resin layers is a layer in which a triangular prepreg is wound in a plan view, and the triangular prepreg is located on the small-diameter end side of the golf club shaft. The length of the golf club shaft in the longitudinal axis direction is {L1 / 3-150 (mm)} with respect to the length L1 (mm) starting from the small diameter end portion. The golf club shaft according to any one of claims 1 to 4, wherein the shaft is {L1 / 3 + 150 (mm)} or less. The method for manufacturing a golf club shaft according to claim 5.
At least, it is provided with a winding step of forming a plurality of fiber reinforced resin layers by winding a plurality of prepregs around the mandrel.
In the winding step, the length of the golf club shaft in the longitudinal axis direction is {L1 / 3-150 mm or more} above the winding start position in the mandrel of the prepreg, which is triangular in plan view. , {L1 / 3 + 150 mm} or less, and wound directly on the mandrel, or wound on a prepreg wound on the mandrel, thereby causing the plurality of fiber-reinforced resin layers. A method for manufacturing a shaft for a golf club, which comprises forming at least one layer of the above.

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