HK1085150A - Golf club shaft - Google Patents

Description

Golf club shaft

Technical Field

The present invention relates to a golf club shaft, and more particularly, to a golf club shaft having a hand feeling similar to that of a steel shaft and having a better stability.

Background

Fig. 8 is a perspective view of a conventional plastic golf club shaft structure. As shown in fig. 8, the structure of the golf club shaft includes: a torsional rigidity holding layer 1 in which reinforcing fibers are obliquely crossed, a flexural rigidity holding layer 2 in which reinforcing fibers are aligned in parallel to the longitudinal direction of the shaft, and optionally a compressive rigidity holding layer 3 in which reinforcing fibers are aligned in perpendicular to the longitudinal direction of the shaft. In general, a golf club shaft is composed of 4 to 6 torsional rigidity holding layers 1 and 4 to 6 flexural rigidity holding layers 2 (for example, the specification of Japanese patent application No. 311678/1995).

In the conventional plastic shaft, a prepreg having reinforcing fibers aligned perpendicular to the longitudinal direction of the shaft is optionally wound on a metal mandrel in the shape of a tapered shaft. Thereafter, a prepreg sheet 4 in which reinforcing fibers are obliquely crossed is wound on the above-mentioned prepreg layer. As shown in fig. 9, the prepreg sheet 4 is made by: the prepreg 41 is overlapped on the prepreg 42, and in the prepreg 41, the reinforcing fiber such as carbon fiber is obliquely arranged in a preset direction, and in the prepreg 41, the reinforcing fiber is arranged in a direction opposite to the preset direction. Then, a prepreg sheet in which reinforcing fibers are arranged in parallel to the longitudinal direction is wound on the prepreg sheet 4, then a tape is spirally wound on the prepreg for fixing, and the thermosetting resin in the prepreg sheet is thermally cured. Hereinafter, a prepreg in which internal reinforcing fibers are aligned in a single direction is referred to as a UD prepreg. In the present embodiment, the concept of the UD prepreg includes not only a prepreg in which internal reinforcing fibers are arranged parallel and perpendicular to the longitudinal direction of the shaft but also an inclined prepreg 41 in which internal reinforcing fibers are arranged obliquely in a predetermined direction and an inclined prepreg 42 in which internal reinforcing fibers are arranged in a direction opposite to the predetermined direction.

In the golf club shaft produced according to the above method, a tape mark for fixing is formed on the surface of the shaft. Therefore, before the product is produced, the surface of the above-mentioned outermost surface of the flexural rigidity holding layer is polished, traces of tapes are removed and the surface is smoothed, paint and printing are applied to the surface, and then a transparent surface layer is formed.

The above plastic shaft is basically manufactured by curing a thermosetting resin contained in the UD prepreg layer in which reinforcing fibers are arranged in the one direction. However, although the reinforcing fiber (e.g., carbon fiber) has an elongation of 15%, most thermosetting resin layers have a small strength and a strong flexibility as compared with the reinforcing fiber. Therefore, the thermosetting resin layer has a sufficient influence in the direction in which the reinforcing fibers are aligned. However, there is a problem that deformation or displacement will occur between the thermosetting resin layers when a force is applied in the thickness direction or the lateral direction. When a ball is struck with a club using the golf shaft manufactured according to the above-described method, there occurs a problem in that it is not easy to achieve a stable shot due to displacement or deformation between thermosetting fiber layers. Therefore, fluctuations in direction and range will occur. And the above-mentioned displacement between thermosetting resin layers deteriorates the feel of a shot. That is, for a high-class player who is used to the feeling of a steel shaft, the above-mentioned displacement between thermosetting resins has a problem that the feeling of the player is different from the feeling of using a steel shaft.

Further, the torsional rigidity holding layer 1 is made by bonding the UD prepregs 41 and 42. There is a problem in that the accuracy of the shaft cannot be improved due to the displacement of the laminated prepreg. Further, since the lamination is performed, there are problems that the number of steps increases and the practicality is lowered. Hereinafter, the above-mentioned torsional rigidity holding layer is referred to as a UD torsional rigidity holding layer.

An object of the present invention is to provide a golf club shaft which requires a small number of steps, is excellent in practicality, and can be easily manufactured. It is another object of the present invention to provide a golf club shaft having high accuracy, reduced displacement between thermosetting resins, capable of obtaining a feeling close to that of a steel shaft and excellent stability.

Disclosure of Invention

In order to solve the above problems, the golf club shaft of the present invention uses a golf club shaft including a torsional rigidity holding layer and a UD flexural rigidity holding layer, wherein the torsional rigidity holding layer is made of a thermosetting resin including reinforcing fibers obliquely crossing a longitudinal direction of the shaft, and the UD flexural rigidity holding layer is made of thermosetting resin, and the resin includes reinforcing fibers arranged in parallel with the longitudinal direction of the shaft, characterized in that at least a part of the torsional rigidity holding layer comprises a plain weave fabric layer, and the plain weave fabric layer is obtained by winding and curing a plain weave prepreg like a shaft shape, wherein the plain weave fabric layer interweaves the thermosetting resin-impregnated warp and weft yarns in the plain weave fabric with each other in such a manner that the warp and weft yarns are obliquely crossed in the longitudinal direction of the shaft.

Further, the golf club shaft of the present invention employs a golf club shaft comprising a torsional rigidity holding layer and a flexural rigidity holding layer, wherein the torsional rigidity holding layer is made of a thermosetting resin including reinforcing fibers obliquely crossing the longitudinal direction of the shaft and the flexural rigidity holding layer is made of a thermosetting resin having reinforcing fibers aligned parallel to the longitudinal direction of the shaft, characterized in that the torsional rigidity holding layer has a plain weave fabric layer and a triaxial fabric layer, wherein the plain weave fabric layer is formed by winding a prepreg and curing the prepreg like a shaft shape, wherein the prepreg is made by impregnating the plain weave fabric having warp yarns and weft yarns interwoven with each other with the thermosetting resin in such a manner that the warp yarns and the weft yarns obliquely cross in the longitudinal direction of the shaft, and wherein the triaxial fabric layer is formed by winding a prepreg obtained by impregnating a triaxial fabric having first warp yarns inclined to weft yarns and second warp yarns inclined to the weft yarns with a thermosetting resin like a shaft shape and curing the prepreg, and the triaxial fabric has a structure in which: these weft yarns and the first and second warp yarns are alternately woven through the upper and lower sides of the yarns so that the weft yarns are parallel or perpendicular to the longitudinal direction of the shaft.

According to the first invention of the present invention, the torsional rigidity holding layer comprises a plain weave fabric layer heat-cured with a thermosetting resin impregnating a plain weave fabric. A plain weave fabric is woven from warp and weft yarns and movement of the yarns is restricted. Thus, the warp exerts a resistive force against the longitudinal force and the weft exerts a resistive force against the transverse force. Therefore, deformation or displacement between thermosetting resin layers can be effectively suppressed. Therefore, since the displacement between the layers can be suppressed at the time of hitting the ball, an advantage can be obtained in improving the stability of the distance and the direction. Another benefit is that the feel is softer, the rebound after bending is slower and the stroke is easier than with a triaxial fabric layer alone. These characteristics are more suitable for iron clubs including putters.

Further, the second invention in the present invention uses the following: a plain weave fabric layer formed by impregnating the plain weave fabric with a thermosetting resin and curing the thermosetting resin, and a triaxial fabric layer using a triaxial fabric as a torsional rigidity holding layer. Since the plain weave fabric and the triaxial fabric are woven by warp and weft, respectively, the movement of the yarns is restricted. Therefore, deformation or displacement between thermosetting resin layers can be effectively suppressed. Further, since it is not necessary to bond the prepreg 42 to the prepreg 41, it is possible to manufacture a golf club shaft which requires a smaller number of steps and has higher practicability and accuracy.

Drawings

FIG. 1 is a cross-sectional view of one embodiment of a golf club of the present invention;

FIG. 2 is a plan view and a sectional view of a plain weave fabric used for a golf club shaft of the present invention;

FIG. 3 is a sectional view of an embodiment of a golf club shaft of the present invention;

FIG. 4 is a sectional view of another embodiment of a golf club shaft of the present invention;

FIG. 5 is a sectional view of still another embodiment of a golf club shaft of the present invention;

FIG. 6 is a sectional view of still another embodiment of a golf club shaft of the present invention;

FIGS. 7a and 7b are schematic diagrams illustrating a triaxial fabric structure;

FIG. 8 is a schematic view of an exemplary structure of a plastic golf club shaft; and

FIG. 9 is a block diagram of a UD prepreg forming a conventional torsional rigidity holding layer.

Detailed Description

One embodiment of the golf club shaft of the present invention has a structure in which: the UD flexural rigidity holding layer 2 is made of a thermosetting resin having reinforcing fibers aligned in parallel with the longitudinal direction of the shaft; the UD compressive rigidity holding layer 3 which is a resin layer having reinforcing fibers selectively aligned in a direction perpendicular to the longitudinal direction of the shaft is formed on the torsional rigidity holding layer 1 made of a thermosetting resin having reinforcing fibers obliquely crossing the longitudinal direction of the shaft, as in the case shown in FIG. 8. The golf club is composed of 4 to 6 UD flexural rigidity holding layers 2.

In the above embodiment of the present invention, the plain weave fabric layer 11 is used on at least a part of the torsional rigidity holding layer 1, wherein the plain weave fabric layer 11 is formed by curing a plain weave prepreg obtained by impregnating a plain weave fabric with a thermosetting resin. FIG. 1 shows a preferred embodiment having the above-described structure, in which a plain weave fabric layer 11 is formed on a UD torsional rigidity holding layer 1, and a UD flexural rigidity holding layer 2 is formed on the layer 11.

Fig. 2a is a plan view of a plain weave fabric used in the present invention, and fig. 2b is a sectional view of the fabric. As shown in fig. 2a and 2b, the plain weave fabric has the following structure: in which the warp 51 and weft 52 are woven at right angles to each other. Further, the plain weave fabric prepreg is wound like a rod on a mandrel and cured so that the warp 51 and weft 52 cross each other at an angle θ of approximately 45 ° to the longitudinal direction of the shaft. In this case, even though the angles of the warp yarns 51 and the weft yarns 52 and the longitudinal axis on the one hand may deviate slightly from 45 ° due to the winding, the warp yarns 51 and the weft yarns 52 are stable because the angle formed between the warp yarns 51 and the weft yarns 52 is 2 θ, that is, 90 °. Therefore, the influence of the torque of the reinforcing fibers is constant, and at the same time, even if the warp 51 and the weft 52 are not accurately wound, the balance is easily achieved. Therefore, the flexibility of design is enhanced and the utility of the shaft is improved. In addition, when the angle of the obliquely crossing reinforcing fibers to the longitudinal direction of the shaft is 45 °, it is possible to exhibit the best twisting effect. Therefore, as described above, it is preferable that the prepreg is wound such that the reinforcing fiber is angled at 45 ° with respect to the longitudinal direction of the shaft.

In a preferred embodiment of the present invention, the yarns of the plain weave fabric are carbon fibers. In another embodiment of the present invention, the warp 51 and weft 52 may use alumina fiber, aramid fiber, tirano fiber, amorphous fiber, or glass fiber. That is, the kind of the yarn is not substantially limited.

In one embodiment of the present invention, the above plain weave fabric preferably has a thread count of 4 yarns/cm or more. When the thread count is less than 4 yarns/cm, the thickness of the plain weave fabric increases and the workability decreases.

Also, the yarn preferably has a thickness of 3K (1K for 1000 filaments) or less. When the thickness exceeds 3K, 1ply becomes too thick and it is also impossible to secure a sufficient fiber density (thread count), and the workability is deteriorated because the yarn is not easily wound around the shaft.

In the present invention, the above-mentioned fabrics of the present invention can be impregnated with essentially any resin as a prepreg resin. For example, an epoxy resin, a non-saturated polyester resin, a phenol resin, a vinyl ester resin, or a peak resin (peak resin) may be used. The thickness of the above prepreg is preferably 0.3mm or less. When the thickness exceeds 0.3mm, 1ply becomes too thick and it is also impossible to secure a sufficient fiber density (thread count) or the workability is lowered because the prepreg is not easily wound around the shaft.

Furthermore, the prepreg preferably has a weight of 400g/m²Or less. When the weight exceeds 400g/m²In time, the prepreg will become too thick. Preferably, the resin content of the prepreg is between 25 and 40 wt%. When the resin amount is equal to 25 wt% or less, it is not possible to manufacture a satisfactory shaft because the resin amount is too small. However, when the tree is usedWhen the amount of fat exceeds 40 wt%, the torque becomes excessive without changing the weight of the shaft. In this specification, the torque indicates the degree of torsion at which 1 ft-lb is loaded to the shaft rotation direction.

In one embodiment of the present invention, the UD flexural rigidity holding layer 2 in which reinforcing fibers are arranged in the shaft longitudinal direction is formed on the torsional rigidity holding layer 1 (plain weave fabric layer 11), and the torsional rigidity holding layer 1 is a resin layer in which the reinforcing fibers form a plain weave fabric as shown in FIG. 8. The prepreg for the compressive rigidity holding layer 3 may be a UD compressive rigidity holding layer using a conventional UD prepreg. The UD flexural rigidity holding layer 2 constitutes the outermost surface layer of the shaft. The shaft thus forms a product: the UD flexural rigidity holding layer 2 is provided, the surface of the UD flexural rigidity holding layer 2 as the outermost surface layer is polished and smoothed, then paint and printing are applied on the layer 2, and finally a transparent surface layer is formed on the layer 2.

Further, in another embodiment of the present invention, it is possible to form the compressive rigidity holding layer 3 of a resin layer in which reinforcing fibers are arranged inside or outside the torsional rigidity holding layer 1(UD torsional rigidity holding layer 10 and/or plain weave fabric layer 11) in a direction perpendicular to the longitudinal direction of the shaft (the direction of the circumference of the shaft). The prepreg for the compressive rigidity holding layer 3 may also be a compressive rigidity holding layer using a conventional UD prepreg.

Further, in another embodiment, in order to adjust shaft characteristics such as hardness, a hitting point, weight and torsional rigidity of the shaft, a UD torsional rigidity holding layer 10 formed of a conventional UD prepreg may be laminated outside the above plain weave fabric layer. In another embodiment, a plain weave fabric layer formed by curing a plain weave prepreg made of a plain weave fabric impregnated with a thermosetting resin may be held with flexural rigidity and/or compressive rigidity. In this case, the flexural rigidity and/or compressive rigidity holding plain weave fabric layer is formed by winding the prepreg so that the warp 51 or weft 52 is parallel to the shaft longitudinal direction and curing the prepreg. In this case, the weft yarns 52 (warp yarns 51) are aligned in parallel with the longitudinal direction of the shaft to contribute to the maintenance of flexural rigidity, and the weft yarns 52 (warp yarns 51) perpendicular to the warp yarns 51 are wound in a direction perpendicular to the longitudinal direction (circumferential direction) of the shaft. Therefore, the weft yarn 52 contributes to the maintenance of the compressive rigidity. In this case, it is possible to obtain the same advantageous effect without forming the compressive rigidity holding layer 3.

When the above plain weave fabric layer is used, the UD flexural rigidity holding layer 2 forms the outermost surface layer which is a resin layer in which reinforcing fibers are arranged in the longitudinal direction of the shaft or a resin layer not including reinforcing fibers. When the UD flexural rigidity holding layer 2 or the resin layer not including the reinforcing fibers is not formed but the fabric layer is on the outermost surface, since the surface of the shaft to be manufactured is polished, the fibers of the fabric layer are cut and the function of the fabric layer is deteriorated.

In the case of the present invention, it is sufficient to have the torsional rigidity holding layer and the flexural rigidity holding layer of the plain weave fabric layer or the resin layer not including the reinforcing fibers formed on the outermost surface. In another construction, the standard torsional rigidity holding layer and the flexural rigidity holding layer as well as the compressive rigidity holding plain weave fabric layer as described above can be combined in a variety of different ways.

Further, in the present invention, it is allowed to form a triaxial fabric layer together with the above plain weave fabric layer. In a typical structure of one shaft of the present invention, a UD compressive stiffness holding layer 3 (which may be referred to as a 90 DEG layer) comprising a resin layer of reinforcing fibers selectively arranged in a direction perpendicular to the longitudinal direction of the shaft is formed over a UD torsional stiffness protective layer 10 { for example, one layer (1ply) }, wherein the UD torsional stiffness holding layer 10 is formed by curing a plurality of UD prepreg sheets (for example, four layers; in this case, the UD prepreg sheets are formed of 2X 4 layers) of thermosetting resin layers, and the reinforcing fibers in the UD prepreg sheets are made by overlapping a slanting prepreg 41 having the reinforcing fibers arranged obliquely in a predetermined direction with a slanting prepreg 42 having the reinforcing fibers arranged in the direction opposite to the predetermined direction shown in FIG. 3, so that the reinforcing fibers are obliquely crossed. The torsional rigidity holding layer 1 formed by the plain weave fabric layer 11 is formed on the UD compressive rigidity holding layer 3. It is permissible to use one or more plain weave fabric layers 11 (e.g., three layers).

Further, the triaxial fabric layer 12 may be formed on the laminated layers with or without one or more UD flexural rigidity holding layers 2 (which may be referred to as 0 ° layers), wherein the UD flexural rigidity holding layers 2 are formed by curing a thermosetting resin layer including reinforcing fibers aligned in parallel to the longitudinal direction. Further, one or more layers of the UD flexural rigidity holding layer 2 or the layer 2 of the 0 DEG layer are formed.

As shown in fig. 7a and 7b, the triaxial fabric layer 12 has a first warp 52 inclined to the weft 51 and a second warp 53 obliquely crossing the warp 52, and these weft 51, warp 52 and warp 53 are alternately interwoven through the upper and lower sides of the yarn and wound like a shaft so that the weft 51 is parallel (0 ° direction) or perpendicular (90 ° direction) to the longitudinal direction of the shaft.

Fig. 4 shows another preferred embodiment. In this embodiment, one or two UD torsional rigidity holding layers 2 or one or two UD compressive rigidity holding layers 3(0 DEG or 90 DEG layers) are laminated on a UD torsional rigidity holding layer 1 (for example, four layers; in this case, a prepreg sheet is formed of 2X 4 layers), wherein the UD torsional rigidity holding layer 1 is formed by: an oblique prepreg 41 in which internal reinforcing fibers are obliquely arranged in a predetermined direction and an oblique prepreg 42 in which internal reinforcing fibers are obliquely arranged in a direction opposite to the predetermined direction are stacked on each other, and a plurality of thermosetting resins of the UD prepreg sheet 4 in which internal reinforcing fibers are obliquely arranged crosswise are cured. The UD torsional rigidity holding layer 10 and the UD flexural rigidity holding layer 2 or the UD compressive rigidity holding layer 3(0 DEG or 90 DEG layers) may be replaced. That is, it is permissible to form the 0 ° layer or the 90 ° layer first and then form the UD torsional rigidity holding layer 10.

Torsional rigidity holding layers (e.g., two or three layers) respectively formed by the plain weave fabric layer 11 are formed on the above-mentioned layers, the triaxial fabric layer 12 is formed on the plain weave fabric layer 11 through the UD flexural rigidity holding layer 2 or the UD compressive rigidity holding layer 3(0 ° or 90 ° layer), and the plain weave fabric layer 21 (e.g., two or three layers) is formed with or without the 0 ° layer 2 or 90 ° layer 3 (e.g., 1 to 2 layers). The plain weave fabric layer 21 is a layer in which warp yarns are wound and cured in a manner parallel to the longitudinal direction of the shaft (so that weft yarns are perpendicular to the direction of the axis), that is, the plain weave fabric layer 21 which retains flexural rigidity and/or compressive rigidity so as to achieve the flexural rigidity and compressive rigidity retaining function.

One or more layers of the UD flexural rigidity holding layer 1(0 ° layer) may be further formed on the plain weave fabric layer 21.

In yet another embodiment shown in FIG. 5, one or more plain weave fabric layers 11 (e.g., two or three layers) that maintain torsional stiffness are formed. One or more UD torsional rigidity holding layers 10 are formed on the plain weave fabric layer 11, and also a triaxial fabric layer 12 is formed, while a flexural rigidity and/or compressive rigidity holding plain weave fabric layer 21 is formed by the 0 DEG layer 2 or the 90 DEG layer 3. The UD flexural rigidity holding layer 10 is formed on the plain weave fabric layer 21.

In the case of the golf club shaft, the above plain weave fabric and plain weave prepreg are effectively used in the plain weave fabric layers 11 and 21.

In the preferred embodiment shown in FIG. 6, a plain weave fabric layer 11 is formed on the UD torsional rigidity holding layer 10, and a triaxial fabric layer 12 is formed adjacent to the layer 11. The UD flexural rigidity holding layer 2 is further formed on the triaxial fabric layer 12.

The triaxial fabric 5 has a first warp 52 obliquely crossing the weft 51 and a second warp 53 obliquely crossing the warp 52. These weft yarns 51, warp yarns 52 and 53 may be woven alternately through the upper and lower sides of the yarns.

The angle theta formed between the weft yarns 52 and the warp yarns 53 is preferably formed between 25-75 deg.. When the angle deviates from the range of 25-75 deg., the isotropy of the triaxial fabric will be lost and the shape-retaining property will be deteriorated. The angle is preferably in the range of 50-70 deg.. Typically, the fabric is preferably made by knitting yarns with warp 51, weft 52 and 53 forming approximately 60 ° with each other.

Although the warp 51, the weft 52 and the weft 53 generally use carbon fibers as in the case of a plain weave fabric, alumina fibers, aramid fibers, tirano fibers, amorphous fibers or glass fibers may be used. That is, the kind of the yarn is not substantially limited. And the carbon fiber includes a pitch type (pitch type) and a pan type (pan type), both of which may be used. It is permissible for the fibers to differ in physical properties, and the differences in physical properties include, for example, tensile strength or modulus of elasticity in elongation even in the same fiber.

The triaxial fabric is preferably formed between 32 and 64 gauge (gauge). Triaxial fabrics outside the above range may degrade the performance of the golf club shaft. In the case of a 32 gauge triaxial fabric, the spacing dx between the weft yarns 51 is 1.80mm and the spacing dy of the crossing points between the warp yarns 52 and 53 is 2.04 mm. In the case of the 64 gauge, dx is 0.90mm and dy is 1.04 mm.

The thickness of the above prepreg is preferably 0.4mm or less. When the thickness exceeds 0.4mm, 1ply becomes too thick, so that a sufficient fiber density (yarn count) cannot be obtained or the practicality of the prepreg is lowered because the prepreg is not easily wound around the shaft.

Further, the weight of the prepreg is preferably 350g/m²Or less. When the weight exceeds 350g/m²When the resin is extremely squeezed into the weave pattern, the prepreg becomes very thick. The resin content of the prepreg is preferably between 25 and 50 wt%. When the resin amount is equal to 25 wt% or less, it is not possible to manufacture a preferable shaft because the resin amount is too small. However, when the resin amount exceeds 50 wt%, the outer diameter of the shaft becomes excessively large.

In one embodiment of the present invention, the UD flexural rigidity holding layer 2 or UD compressive rigidity holding layer 3 is constituted of a 0 DEG layer or a 90 DEG layer, and this layer 2 or 3 is disposed between the plain weave fabric layer 11 and the triaxial fabric layer 12 (i.e., between the woven fabric layers). Alternatively, a UD torsional rigidity holding layer 10 is provided therebetween. The above structure is used to prevent the fabric layers 11 and 12 from directly contacting each other. When the fabric layers 11 and 12 are in direct contact with each other, the amount of resin becomes insufficient, the peel strength between the layers is insufficient, and displacement between the layers may occur. In order to prevent this, a 0 ° layer or a 90 ° layer is provided. It is of course important that the 0 ° layer retains flexural rigidity and the 90 ° layer retains compressive rigidity. Moreover, in another embodiment, it is possible to arrange the plain weave fabric layer 11 and the triaxial fabric layer 12 in contact with each other (that is, to arrange the fabric layers in contact with each other).

In still another embodiment of the present invention, as shown in FIGS. 3 to 6, the UD flexural rigidity holding layer 2 is formed on the fabric layers 11 and 12 or the fabric layer 21. The UD flexural rigidity holding layer 2 constitutes the outermost surface layer of the shaft. Moreover, in still another preferred embodiment, a transparent resin layer excluding reinforcing fibers is formed on the UD flexural rigidity holding layer 2 or the fabric layers 11, 12 and 21. After the UD flexural rigidity holding layer 2 and/or the transparent resin layer is provided, the product is produced by polishing and smoothing the surface of the UD flexural rigidity holding layer 2 on the outermost surface, followed by painting and printing on the surface to form a transparent surface layer.

In the above-described embodiment, the triaxial fabric layer 12 and the plain weave fabric layer 11 are formed over the entire length of the shaft. However, it is also possible to form part of the layers 12 and 11 on the chipping and/or striking side. Further, the layer 12 and the layer 11 may be formed in a part of the ball cutting and/or striking side or may be formed separately in the center of the shaft.

Examples 1 and 2

The golf club shaft is manufactured using a plain weave fabric as shown in fig. 2. The golf club shaft is formed by: 3 layers of the plain weave prepreg of the present invention (amount of resin: 40%; modulus of elasticity of reinforcing fiber: 24t), 1 layer of UD prepreg arranged perpendicular to the shaft longitudinal direction (each of these prepregs: amount of resin: 40%; modulus of elasticity of reinforcing fiber: 24t), and 2 layers of flexural rigidity holding UD prepreg having reinforcing fiber arranged parallel to the shaft longitudinal direction (amount of resin: 24%, modulus of elasticity of reinforcing fiber: 30t) were wound on a mandrel and cured. The plain weave prepreg was wound around the imaging shaft so that the warp 51 and weft 52 of the plain weave fabric crossed each other at an angle θ of approximately 45 ° in the longitudinal direction of the shaft (example 1).

Further, the plain weave prepreg (40% in the amount of resin; 24t in the modulus of elasticity of reinforcing fiber) in the present invention is wound in 3 layers like a shaft so that the warp 51 and weft 52 of the plain weave fabric cross each other in the longitudinal direction of the shaft at an angle θ of approximately 45 ° (see the arrow in fig. 1). Next, 1 layer of plain weave prepreg (40% in resin amount; 24t in elastic modulus of reinforcing fiber) was wound so that the warp 51 or weft 52 was parallel to the longitudinal direction of the shaft (or the weft or warp was perpendicular to the longitudinal direction of the shaft). Further, a flexural rigidity holding CD prepreg having reinforcing fibers aligned parallel to the shaft longitudinal direction (resin amount: 24%; reinforcing fibers having an elastic modulus of 30t) was wound in 2 layers on a mandrel and cured to form a golf club shaft (example 2).

Also, for comparison, a golf club shaft was manufactured by using the following layers: instead of the plain weave fabric layer, 3 UD torsional rigidity holding layers (UD prepreg 41: 3 layers and UD prepreg 42: 3 layers) (resin amount: 40%; elastic modulus of reinforcing fiber: 24t), 1 UD prepreg having reinforcing fibers aligned parallel to the shaft, 1 UD prepreg having reinforcing fibers aligned perpendicular to the longitudinal direction of the shaft (above each layer of prepreg, resin amount: 40%; elastic modulus of reinforcing fiber: 24t) and 2 UD flexural rigidity holding layers (resin amount: 24%; elastic modulus of reinforcing fiber: 30t) (comparative example 1) were provided.

Carbon fiber yarns (3K) are used as reinforcing fibers for each layer. Further, carbon fibers are used for the warp and weft in the plain weave fabric, respectively. The thickness of each of the warp and weft yarns was 3K, and the yarn count of each of the warp and weft yarns was 4.9 yarns/cm. In addition, whenWhen a plain weave prepreg was used, the thickness was 0.22mm and the weight was 328g/m²。

The characteristics of the above golf club shaft are as follows.

TABLE 1

	Example 1	Example 2	Comparative example
				Length of	46in	46in	46in
Weight (D)	67.2g	67.9g	67.8g
				Torque of	5.8°	5.65°	5.67°
Frequency of	245cpm	244cpm	244cpm

Golf club shafts (each shaft is 45 inches in length) were respectively manufactured by providing 51g of the same grip and 194g of the same head so that the robot hit golf balls under the same conditions. The robot is arranged in such a way that: the position of the robot at which the head hits the ball is the same for all clubs, and the speed of the head is 40 m/s.

As a result of hitting 100 golf balls at the center of the head of the golf club using the shaft of example 1 of the present invention, the ball drop point (throw) was approximately 198.7yd, the error in the back and front directions (throw) was + -3.75 yd, and the error in the lateral direction was + -5.5 yd. Further, as a result of hitting 100 golf balls by moving the hitting position of the head 10mm to the tip side, the ball has a landing point (range) of approximately 196.4yd, an error in the rear and front directions (range) of ± 3.9yd, an error in the lateral direction of ± 4.5yd and an error in the range equal to an error in hitting the ball at the center of the head. However, when the hitting point is moved by 10mm, the error in the lateral direction is smaller.

However, when 100 golf balls were hit on the head of the golf club using the shaft shown in example 2 of the present invention, the ball drop point (throw) was approximately 197.9yd, the error in the back and front directions (throw) was ± 2.95yd, and the error in the lateral direction was ± 4.1 yd. Further, as a result of hitting 100 golf balls by moving the hitting position of the head 10mm to the tip side, the ball has a landing point (throw) close to 193.1yd, an error in the rear and front directions (throw) of ± 3.55yd, and an error in the lateral direction of ± 3.6yd, and although the error in the throw is the same as in the case of hitting the ball at the center of the head, the error in the lateral direction is smaller when the hitting point is moved to the tip side by 10 mm.

In the case of a golf club formed by a conventional shaft, when a ball is hit at the center of the head of the shaft, the ball has a drop point (throw) close to 193.7yd, an error of ± 5.7yd in the rear and front directions (throw), and an error of ± 5.85yd in the lateral direction. Further, when the golf ball is hit by moving the hitting position of the head by 10mm to the tip side, the ball has a landing point of approximately 193.7yd, an error of ± 9.25yd in the rear and front directions (range), and an error of ± 4.5yd in the lateral direction.

That is, in the case of example 1, the error in the rear and front directions is smaller and the stability of the distance in example 1 is higher compared to comparative example 1. Since the error in the lateral direction of the golf club shaft in example 1 is smaller than that using the conventional club, although the torque of the shaft in example 1 is larger than that of the conventional shaft, the shaft in example 1 can be used as a stable golf club shaft. However, as a result of comparing example 2 with comparative example 1, it was found that the stability of the shaft of example 2 in both the rear and front directions and the lateral direction was excellent. Further, the golf shaft of the present invention has relatively slow response characteristics, respectively, and easily collides with a ball, so that controllability is improved.

From the above results, it is considered that since the plain weave fabric is woven, the movement of the warp and weft is small. For this reason, since the displacement between the plain weave fabric layers and between the plain weave fabric layer and the flexural rigidity layer is reduced, stability is produced in the distance and direction, while torsional rigidity is increased because the movement of the warp and weft is small. From these results, it has been found that a particularly useful cue stick can be made for iron clubs requiring distance and directional stability. Further, since the plain weave layer has a great isotropy, a feeling similar to that of iron can be obtained.

Example 3

The golf club shaft is manufactured using a plain weave fabric as shown in fig. 2. The golf club shaft is formed by: a mandrel was wound with 3 layers of plain weave prepreg (amount of resin: 40%; elastic modulus of reinforcing fiber: 24t), 3 layers of UD prepreg obtained by stacking an inclined prepreg in which reinforcing fibers are disposed obliquely in a predetermined direction (amount of resin: 40%; elastic modulus of reinforcing fiber: 24t) and an inclined prepreg in which reinforcing fibers are disposed in a direction opposite to the predetermined direction (amount of resin: 40%; elastic modulus of reinforcing fiber: 24t) (3 × 2 prepreg was used), and 4 layers of conventional flexural rigidity holding UD prepreg having reinforcing fibers aligned parallel to the longitudinal direction of the shaft (amount of resin: 24%; elastic modulus of reinforcing fiber: 30t) and curing them.

Further, the plain weave prepreg is wound in a shape like a shaft so that the warp 51 and the weft 52 cross each other at an angle θ of 45 ° in the longitudinal direction of the shaft (see the arrow shown in fig. 2).

Carbon fibers are used for each layer of reinforcing fibers. Carbon fibers are used for the warp and weft of all plain weave fabrics. The thickness of each warp and each weft was 3K, and the yarn count of the warp and weft was 4.9 yarns/cm. Further, when a plain weave prepreg was produced, the thickness was 0.22mm and the weight was 328g/m²。

Also, for comparison, a golf club was manufactured using 6 conventional UD torsional rigidity protective layers (UD prepreg 41: 6 layers and UD prepreg 42: 6 layers) (resin amount: 40%; elastic modulus of reinforcing fiber: 24t) and 4 UD flexural rigidity holding layers (resin amount: 40%; elastic modulus of reinforcing fiber: 30t) (compare with example 2). Carbon fiber (3K) was used as the yarn among the reinforcing fibers.

The characteristics of the above golf club shaft are as follows.

TABLE 2

	Example 3	Comparative example 2
			Length of	46in	46in
Weight (D)	98.4g	99.3g
			Torque of	3.2°	2.8°
Frequency of	264cpm	264cpm

Golf clubs (each shaft is 45 inches in length) were made by providing 51g of the same grip and 194g of the same head so that the robot hit the golf ball under the same conditions. The robot is arranged in such a way that: the position of the robot at which the head hits the ball is the same for all clubs, and the speed of the head is 40 m/s.

As a result of hitting 100 golf balls at the center of the head of a golf club using the shaft of the present invention, the ball has a drop point (shot) close to 189yd, an error of + -4 yd in the rear and front directions (shots), and an error of + -4.7 yd in the lateral direction. Further, as a result of hitting 100 golf balls by moving the hitting position of the head by 10mm toward the tip side, the ball has a drop point (throw) of 188.7yd, an error in the rear and front directions (throw) of ± 4yd, and an error in the lateral direction of ± 8yd, and in this case, the error in the throw is the same as the error in hitting the ball at the center of the head.

However, in the case of a golf club using a conventional shaft, the ball has a drop point close to 188yd, an error of ± 6yd in the rear and front directions (range), and an error of ± 5yd in the lateral direction. Further, when 100 golf balls were hit by moving the hitting position of the head 10mm to the tip side, the ball was dropped to a point of 185yd with an error of ± 6.6yd in the rear and front directions (range) and an error of ± 10yd in the lateral direction.

That is, the golf club shaft of the present invention shows very excellent distance stability as compared with the conventional golf club shaft. Further, we have found that the golf club shaft of the present invention and the comparative example each have a relatively slow reaction characteristic, easily hit a ball, and thus have an enhanced controllability. Further, since the error in the lateral direction of the golf club shaft in example 3 is small, the golf club shaft can be used as a stable golf club shaft.

The following are test characteristic results of the golf club shaft of the present invention and the conventional golf club shaft

TABLE 3

	Example 3	Traditional pole body	Rate of increase
				Rotary ball	2,600-2,700	Approaching 3,000	The reduction is 10 percent
Angular fluctuation of striking face			The fluctuation is reduced by 30 percent
				(center) range	189±4	185±6	Fluctuation was reduced by 40% (10 mm moving to the tip side)

From the above results, it is considered that since the plain weave fabric is woven flat, the movement of the warp and weft is small, and further, since the movement of the warp and weft is small, the displacement between the plain weave fabric layers and between the plain weave fabric layer and the flexural rigidity layer is small, the distance and direction are stabilized, and the torsional rigidity is increased. Therefore, a particularly useful cue stick can be made for steel cues requiring distance and directional stability. Further, since the plain weave layer has a great isotropy, a feeling similar to that of iron can be obtained.

From the above results, it was found that the golf club shafts of examples 1 and 3 of the present invention had a small error in the rear and front directions (range), and the stability of the distance was improved as compared with the conventional shaft. Further, in the example of example 2, it was found that not only the stability of the distance was improved but also the error in the lateral direction was increased, so that example 2 was a preferable golf club shaft. From these results, it was found that the golf club shaft of example 2 is the most suitable shaft for the iron body which is required to have a small error in the back and front or in the lateral direction.

As described above, according to the golf club shaft of the present invention, the plain weave fabric layer obtained by impregnating the plain weave fabric with the thermosetting resin and curing the fabric is used as the torsional rigidity holding layer. A plain weave fabric is woven from warp yarns and weft yarns, and thus the movement of the yarns is restricted. Therefore, since the warp yarn exhibits resistance against a longitudinal force and the weft yarn exhibits resistance against a lateral force, it is possible to effectively restrict the deformation or displacement between the thermosetting resin layers. Therefore, it is possible to restrict the displacement between the layers at the time of shooting, and the golf club shaft can be made into a golf club shaft having stability and feeling the same as that of the iron body.

Examples 4 and 5

The golf club shaft is manufactured by using the plain weave fabric and the triaxial fabric shown in fig. 2 and 7. The golf club shaft is made of two prepreg sheets 4 in which reinforcing fibers are obliquely arranged in a preset direction, 3 plain weave prepreg sheets, 1 triaxial fabric prepreg and 30 ° layer prepreg sheets in which the reinforcing fibers are obliquely crossed (refer to a UD torsional rigidity holding layer) (prepreg is 2 × 2 layers), in which reinforcing fibers are obliquely arranged in a preset direction, and 3 layers of 0 ° layer prepreg, in which reinforcing fibers are arranged in a direction opposite to the preset direction as an innermost layer torsional rigidity holding layer 1, which are continuously wound on a mandrel, wherein the reinforcing fibers are obliquely arranged in the inclined prepreg 41 and the surface of the shaft is polished (example 4; see FIG. 6).

The resin amount of the plain weave prepreg was 40%, and the resin amount of the 0 ° ply prepreg was 25%. The plain weave prepreg is wound like a shaft so that warp yarns and weft yarns cross each other at an angle of approximately 45 ° in the longitudinal direction of the shaft. Carbon fibers are used for the reinforcing fibers of the UD torsional rigidity holding layer, the 0 DEG layer and the plain weave layer. Each warp and each weft of the plain weave layer had a thickness of 3K and a warp and weft count of 4.9yarns/cm, respectively. Furthermore, the thickness of the prepreg was 0.22mm and the weight was 328g/m²。

Also, the thickness of the warp and weft of the triaxial fabric is set to 1K, respectively, and the angle of the weft to the warp is set to 60 °. A triaxial fabric (32 gauge) was impregnated with 40% resin to make a prepreg. Furthermore, the thickness of the prepreg was 0.175mm and the total weight was 122g/m². The prepreg was wound in such a manner that the weft yarn was perpendicular (90 ° direction) to the shaft.

The golf club shaft (example 5, see fig. 1) was manufactured by: two layers of the above-mentioned UD torsional rigidity holding layer, three plain weave tissue layers and three flexural rigidity holding layers (0 ℃ layer) were used. In addition, for comparison, a golf club shaft (comparative example 3) was manufactured by using four layers of the above-described UD torsional rigidity holding layer and three layers of flexural rigidity holding layers (0 ° layers).

A 45-inch golf club was prepared by providing a head and a grip on the above golf shafts a (example 4), B (example 5) and C (comparative example 3).

TABLE 4

	Frequency of	Club weight	Head weight	Weight of shaft	Weight of handle
						A	254	321.9g	194.9g	71.2g	50.7g
B	255	323.3g	194.6g	72.1g	50.5g
						C	255	325.7g	194.0g	74.7g	50.6g

In table 4 above, the unit of frequency is CPM. For the torque of the shaft, a was 4.26 °, B was 3.98 ° and C was 4.07 °.

The golf ball is hit by a robot under the same conditions using the above three golf clubs. The robot is arranged in such a way that: the position of the robot at which the head hits the ball is the same for all clubs, and the head speed is 42 m/s.

As a result of hitting 100 golf balls with a robot at the center of the head of the golf club A using the shaft of the present invention, the ball drop point (shot) was close to 205yd, the error in the back and front directions (shots) was + -3 yd, and the error in the lateral direction was + -4.25 yd. Then, as a result of moving the hitting position of the head by 10mm toward the tip side and hitting 100 golf balls by the robot, the ball drop point approaches 200.7yd, the error in the rear and front directions (range) is ± 3yd, and the error in the lateral direction is ± 3.75 yd.

In the case of the golf club B, as a result of hitting the ball at the center of the head, the ball has a landing point close to 206yd, an error of + -3.75 yd in the rear and front directions (range), and an error of + -5.0 yd in the lateral direction. When the robot struck 100 golf balls by moving the hitting position 10mm toward the tip side, the ball drop point was close to 200.6yd, the error in the rear and front directions was ± 4.5yd, and the error in the lateral direction was ± 2.75 yd.

However, in the case of the golf club C, as a result of hitting the ball at the center of the head, the ball has a landing point close to 206yd, an error of ± 5.7yd in the rear and front directions (range), and an error of ± 6.5yd in the lateral direction. Further, when 100 golf balls were hit with the shot position shifted 10mm to the tip side, the ball dropped to a point close to 202.7yd with an error of + -5.25 yd in the rear and front directions and an error of + -4.0 yd in the lateral direction.

That is, the golf club a of the present invention shows better distance stability with respect to the golf clubs B and C. Particularly, the golf club shaft of the present invention has an improved distance and span as compared with the conventional UD prepreg golf club C, while a stable golf club shaft can be obtained.

Claims (33)

1. A golf club shaft comprising a torsional rigidity holding layer made of a thermosetting resin including reinforcing fibers obliquely crossing the longitudinal direction of said shaft and a UD flexural rigidity holding layer made of a thermosetting resin including reinforcing fibers aligned parallel to the longitudinal direction of said shaft, characterized in that at least a part of said torsional rigidity holding layer comprises a plain weave fabric layer obtained by winding and curing a plain weave prepreg like a shaft shape, wherein the plain weave prepreg interweaves warp yarns and weft yarns impregnated with a thermosetting resin in the plain weave fabric with each other in such a manner that said warp yarns and weft yarns obliquely cross in the longitudinal direction of said shaft.

2. The golf club shaft of claim 1, comprising a UD compressive stiffness holding layer reinforced with reinforcing fibers in a direction perpendicular to a longitudinal direction of the shaft.

3. The golf club shaft according to claim 1, comprising a torsional rigidity holding layer of a plain weave fabric layer and a UD torsional rigidity holding layer made by winding and curing a UD prepreg sheet having reinforcing fibers crossing each other in a skewed manner by stacking two layers of oblique prepregs, one of the two layers of oblique prepregs being disposed on a slant so that the reinforcing fibers are in a predetermined direction and the other of the two layers of oblique prepregs being disposed on a slant so that the reinforcing fibers are in a direction opposite to the predetermined direction.

4. The golf club shaft according to claim 1, comprising a torsional rigidity holding layer of a plain weave fabric layer and a plain weave fabric layer holding a flexural rigidity and/or a compressive rigidity, wherein the plain weave fabric layer is formed by winding a plain weave prepreg and curing the prepreg in such a manner that weft yarns or warp yarns are parallel to a longitudinal direction of the shaft like a shaft shape.

5. The golf club shaft according to claim 1, wherein the plain weave layer, the UD flexural rigidity holding layer, the compressive rigidity holding layer and the flexural rigidity holding layer are laminated in this order.

6. The golf club shaft according to claim 4, wherein the plain weave fabric layer, the plain weave layer of the flexural rigidity, compressive rigidity and UD torsional rigidity holding layer are laminated in this order.

7. The golf club shaft according to claim 1, wherein the plain weave layer, the UD torsional rigidity holding layer and the UD flexural rigidity holding layer are laminated in this order.

8. The golf club shaft according to claim 1, wherein the UD torsional rigidity holding layer, the plain weave fabric layer and the UD flexural rigidity holding layer are laminated in this order.

9. The golf club shaft according to claim 1, wherein a yarn count of the plain weave fabric is 4/cm or more.

10. The golf club shaft according to claim 1, wherein a yarn thickness of the plain weave fabric is 3K or less.

11. The golf club shaft of claim 1, wherein the weight of the plain weave prepreg is 400g/m²Or less, and the thickness is 0.3mm or less.

12. The golf club shaft according to claim 1, wherein the resin amount of the plain weave prepreg is between 25 to 40 wt%.

13. The golf club shaft of claim 1, wherein the angle of the warp and weft of the plain weave fabric is 90 °.

14. The golf club shaft of claim 13, wherein the warps and wefts of the plain weave fabric are wound so as to make an angle of approximately 45 ° with the longitudinal direction of the shaft.

15. A golf club shaft comprising a torsional rigidity holding layer made of a thermosetting resin including reinforcing fibers obliquely crossing the longitudinal direction of the shaft and a UD flexural rigidity holding layer made of a thermosetting resin including reinforcing fibers aligned parallel to the longitudinal direction of the shaft, characterized in that the torsional rigidity holding layer comprises a plain weave fabric layer made by winding a plain weave prepreg like a shaft shape and curing the prepreg, and a triaxial fabric layer made by impregnating the plain weave fabric having warp yarns and weft yarns interwoven with each other with a thermosetting resin in such a manner that the warp yarns and weft yarns are obliquely crossed in the longitudinal direction of the shaft, and the triaxial fabric layer is formed by winding a triaxial fabric prepreg like a shaft shape and curing the prepreg, wherein the triaxial fabric prepreg is obtained by impregnating a triaxial fabric having first warp yarns inclined to weft yarns and second warp yarns inclined to cross the first warp yarns with a thermosetting resin, and having a structure in which: these warp yarns and weft yarns alternately pass through the upper and lower sides of the yarns in such a manner that the weft yarns are parallel or perpendicular to the longitudinal direction of the shaft.

16. The golf club shaft of claim 15, comprising said UD compressive stiffness holding layer.

17. The golf club shaft according to claim 14, comprising a UD flexural rigidity holding layer and/or a UD compressive rigidity holding layer between the triaxial fabric layer and the plain weave fabric layer.

18. The golf club shaft according to claim 15, wherein the UD torsional rigidity holding layer, the plain weave fabric layer and the UD flexural rigidity holding layer or the UD compressive rigidity holding layer, the triaxial fabric layer and the UD flexural rigidity holding layer are laminated in this order.

19. The golf club shaft of claim 15, wherein the UD torsional rigidity holding layer, the plain weave fabric layer, the triaxial fabric layer and the UD flexural rigidity holding layer are laminated in this order.

20. The golf club shaft according to claim 15, comprising a plain weave fabric layer maintaining flexural rigidity and/or compressive rigidity, the plain weave fabric layer being made by winding warp or weft like a shaft shape in such a manner that the warp or weft is parallel to a longitudinal direction of the shaft and curing.

21. The golf club shaft according to claim 20, wherein the following layers are laminated in order; the UD torsional rigidity holding layer, the UD compressive rigidity holding layer, the plain weave fabric layer, the UD compressive rigidity holding layer, the triaxial fabric layer, the UD compressive rigidity holding layer, the plain weave fabric layer for holding flexural rigidity and/or compressive rigidity, and the UD flexural rigidity holding layer.

22. The golf club shaft according to claim 20, wherein the following layers are laminated in order; the UD flexural rigidity holding layer or UD compressive rigidity holding layer, the UD torsional rigidity holding layer, the plain weave fabric layer, the UD flexural rigidity holding layer or UD compressive rigidity holding layer, the triaxial fabric layer, the UD flexural rigidity holding layer or UD compressive rigidity holding layer, the plain weave fabric layer for holding flexural rigidity and/or compressive rigidity, and the UD flexural rigidity holding layer.

23. The golf club shaft according to claim 20, wherein the following layers are laminated in order; the plain weave fabric layer, UD torsional rigidity holding layer, triaxial fabric layer, UD flexural rigidity holding layer or UD compressive rigidity holding layer, and the plain weave fabric layer and UD flexural rigidity holding layer for holding flexural rigidity and/or compressive rigidity.

24. The golf club shaft according to claim 15, wherein a yarn count of the plain weave fabric is 4/cm or more.

25. The golf club shaft according to claim 15, wherein a yarn thickness of the plain weave fabric is 3K or less.

26. The golf club shaft of claim 15, wherein the weight of the plain weave prepreg is 400g/m²Or less, the thickness is 03mm or less.

27. The golf club shaft of claim 15, wherein the resin amount of the plain weave prepreg is between 25 and 40 wt%.

28. The golf club shaft of claim 15, wherein the angle of the warp and weft of the plain weave fabric is 90 °.

29. The golf club shaft according to claim 15, wherein in case of the plain weave fabric, the warp and weft are wound such that: so as to be at an angle of approximately 45 deg. to each other in the longitudinal direction of the shaft.

30. The golf club shaft of claim 15, wherein the triaxial fabric is 32 or 64 gauge.

31. The golf club shaft of claim 15, wherein the prepreg of the triaxial fabric has a weight of 350g/m²Or less, and 0.4mm or less in thickness.

32. The golf club shaft of claim 15, wherein the resin amount of the prepreg of the triaxial fabric is between 25 and 50 wt%.

33. The golf club shaft of claim 15, wherein the triaxial fabric has an angle between warp and weft of 60 °.