JP3807772B2 - Golf club shaft made of fiber reinforced plastic - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a shaft for a golf club made of fiber reinforced plastic, and more particularly to a shaft for a golf club made of fiber reinforced plastic formed by a braided string machine.
[0002]
[Prior art]
Since the shaft made of fiber reinforced plastic is lighter than the shaft made of metal, there is an advantage that the head speed increases during the swing, and as a result, the flying distance of the ball increases. As a method for producing the fiber-reinforced plastic shaft, a sheet winding method and a filament winding method are generally used.
The sheet winding method is generally formed by winding an alignment sheet, which is formed by aligning reinforcing fibers, impregnating a resin, and prepreging, around a mandrel, and then heat-curing it by taping.
The shaft manufactured by the sheet winding method has a manufacturing process, where the winding start portion and the winding end portion of the prepreg sheet overlap or do not overlap, resulting in a step, or a unidirectionally aligned sheet. Since the wire is cut into a trapezoidal shape and wound, the bending rigidity of the shaft does not become uniform in the circumferential direction because the winding angle is different at the beginning and end of winding, making it difficult to achieve a stable shaft. In addition, since the shear elastic modulus is small, the shaft is easily twisted during a swing, it is difficult to control the orientation of the face of the head, and it is difficult to carry the ball to the target location.
[0003]
The filament winding method is generally formed by winding a reinforcing fiber impregnated with resin around a mandrel in a helical manner, taping it, and heat-curing it.
The shaft manufactured by the filament winding method has a uniform bending rigidity in the circumferential direction and a small twist, but the reinforcing fiber is oriented in the 0 ° direction with respect to the axial direction of the shaft due to its manufacturing method. Therefore, the bending rigidity becomes small and sufficient bending strength cannot be obtained.
Further, if the bending strength is to be satisfied, the amount of fibers wound around the mandrel must be increased, the weight increases, and the advantage of being easy to swing with the original lightweight fiber reinforced plastic shaft cannot be realized.
[0004]
Therefore, in view of the above circumstances, in order to reduce the twist of the shaft, to be light and easy to swing, and to realize stable quality at the same time, as shown in FIG. In the forming step, warp yarns parallel to the axis of the tubular body are supplied to either the inner surface of the braid layer composed of the left and right braids a, a ′ and the intermediate surface of the left and right braids a, a ′, or both sides. A method of manufacturing a tubular body such as a golf shaft or a fishing rod, in which a warp (hereinafter referred to as a center yarn b) layer is simultaneously formed when forming a braid, is known (see JP-A-6-278216).
[0005]
[Problems to be solved by the invention]
However, in the golf shaft manufactured by the conventional method,
When forming a braid with yarn that is not impregnated with resin, the resin is impregnated after the braid is formed. In this case, the resin impregnation step after forming the braid or taping after the resin impregnation is performed. In the taping process at the time of heat curing, the wound yarn tends to be disturbed and meanders, and the shaft performance as designed is not reproduced.
[0006]
In general, the thickness of the fiber reinforced plastic golf shaft needs to be 1 mm or more even at the thinnest part in order to maintain the strength. However, this thickness should be obtained in one assembly forming process as in the conventional method. Then, the number of single fibers constituting the left and right braids a, a ′ and the center yarn b must be increased to increase the thickness of each yarn,
The intersection part c of a ′ or the intersection part d in which the central yarn b is further added to the intersection part of the left and right braids a, a ′ has a thickness of about 2 to 3 times, and a part that does not intersect the intersection part Since the step becomes large, large irregularities are formed on the surface of the shaft.
Therefore, when manufacturing a golf shaft by forming a braid, it is necessary to form a braid layer with thin threads and laminate the braid layer a plurality of times until a desired thickness is obtained.
[0007]
If the braided layer is laminated as described above, the necessary fiber thickness can be secured, but the braided layer increases as the outer layer of the shaft increases, so the braided layer is knitted. The gap portion e formed between the left and right braided yarns a, a ′ and the central yarn b is formed larger as it becomes the outer layer of the shaft.
When forming the braid layer on the mandrel, each yarn forming the braid layer is given to each yarn forming the braid layer by a knitting string machine and acting in the longitudinal direction of the yarn, and other yarns during braiding. When the yarn is pre-impregnated with the frictional resistance generated by the contact, and the resin is fixed in a desired position by the frictional resistance including adhesion of the impregnated resin, the gap portion e is large, that is, When the distance between the braided yarns a and a ′ and the central yarn b is not close, the frictional resistance due to contact with the yarn to be knitted can hardly be expected except at the intersecting portion. It depends on the tensile tension acting in the longitudinal direction.
Therefore, each yarn is strong against an external force acting in the longitudinal direction, but weak against an external force acting perpendicularly to the yarn or at an angle, and a braid layer is formed with yarns not previously impregnated with a resin. After layering the material layer, place it in a mold for molding, and insert the resin for shaft molding into the mold by using RI (resin injection) method or RIM (reaction injection molding, reaction injection molding) method. When injected with pressure, there is a drawback in that the wound yarn is distorted and meandered due to the wraparound of the resin or the like.
[0008]
Moreover, after forming a braided layer with yarn pre-impregnated with resin, after laminating the braided layer, it is wound in a spiral shape at a certain angle with respect to the shaft axis with a heat-resistant wrapping tape such as polypropylene and polyester, When heating, melting the impregnated resin, impregnating between reinforcing fibers and curing molding, if the yarn interval is not close, the wound yarn is distorted and meandered by the tension of the taping. In this case, in particular, the center yarn is liable to be displaced in the direction in which the tape tension acts, and there is a drawback that the designed strength cannot be reproduced.
[0009]
By the way, the winding angle of the braid can be freely adjusted by changing the rotational speed of the knitting string machine and the transfer speed of the mandrel.
Therefore, according to the method, it is possible to increase the winding angle of the braided yarn with respect to the shaft axis (0 degree) as the outer layer portion of the shaft and the shaft large diameter portion to increase the yarn interval. By using this method, the interval between the yarns is reduced and the yarn is not disturbed. However, since the yarn interval is increased by increasing the winding angle of the braid, the bending rigidity and bending strength of the shaft are sufficient. It did not become value. For this reason, in order to satisfy the bending rigidity and strength of the shaft, the winding amount of the braid must be further increased, and there is a drawback that it cannot be called a lightweight shaft and becomes a heavy shaft.
Accordingly, in light of the above-mentioned drawbacks of the prior art, the present invention provides a lightweight golf club shaft that satisfies the target characteristics of the golf club shaft, such as bending strength, torsion, and bending rigidity, and has stable quality. The purpose is to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention comprises a plurality of braid layers comprising a braid having a winding angle symmetrical to the shaft axis and a central yarn having a winding angle of 0 ° with respect to the shaft axis. in the fiber reinforced plastic golf club shaft is formed, the yarn constituting the braid layer, in accordance becomes the outer layer from the inner layer, the number of single fibers are converged to the number or the central thread of the central yarn A shaft for a golf club made of fiber reinforced plastic having a structure increased gradually.
The structure in which the number of yarns constituting the braided layer or the number of single fibers focused on the yarn is sequentially increased from the inner layer to the outer layer depends on the design of characteristics such as the bending rigidity and torsional rigidity of the shaft. The configuration may be such that the number of central yarns or the number of single fibers focused on the central yarn is sequentially increased, or the number of braids or the number of single fibers focused on the braid is sequentially increased. it can.
[0011]
In addition, as the yarn used in the present invention, carbon fiber, glass fiber, alumina fiber, inorganic fiber such as silicon carbide fiber, organic fiber such as aramid fiber, polyparaphenylene benzobisoxazole fiber, boron fiber, stainless fiber, Can be selectively used from a single or mixed fiber bundle of metal fibers such as titanium fibers,
The number of single fibers bundled in the yarn can be 1000 to 24000, but 1000, 3000, 6000, and 12000 are more preferable because they are easy to wind.
Molding resins include thermosetting resins such as epoxy resins, unsaturated polyester resins, phenol resins, polyurethane resins, cross-linked epoxy-modified polyaminoamide resins, polypropylene resins, polyphenylene sulfide resins, polyether ether ketone resins, polyether sulfones. It can be selectively used from thermoplastic resins such as resin, ABS resin and nylon resin.
[0012]
When used in the state where the resin is impregnated in advance with the yarn, the resin content of each yarn is in the range of 20% to 50% in volume ratio for each yarn regardless of the distinction between the braided yarn and the central yarn. Can be adjusted freely.
The shaft of the present invention has a weight of 35 to 60 g and a natural frequency of 190 to 210 c. p. m. In the FRP shaft, the position 90 mm from the small diameter portion of the shaft, this portion is the most easily broken due to stress concentration when the ball is hit with a golf club, and the bending strength at this position is 120 kgf to 150 kgf It is a thing.
Note that if the bending strength is 150 kgf or more, the shaft rigidity is adversely affected, the amount of reinforcing fibers increases, and the shaft weight increases, which is not preferable for the shaft of the present invention.
[0013]
[Action]
A shaft for a golf club made of fiber reinforced plastic according to the present invention comprises a plurality of braids comprising a braid having a winding angle symmetrical to the shaft axis and a central yarn having a winding angle of 0 ° with respect to the shaft axis. A shaft for a golf club made of fiber reinforced plastic formed by layers, and each thread constituting the braided layer sequentially increases the number of yarns or the number of single fibers focused on the yarns from the inner layer to the outer layer. By increasing the configuration, the yarn spacing becomes dense and the frictional resistance generated by the contact of each yarn can be increased. In the resin impregnation step after forming the assembly, or after the resin impregnation In the taping process, the yarn is not disturbed.
[0014]
In the case where the number of yarns constituting the braided layer or the number of single fibers focused on the yarn is sequentially increased from the inner layer to the outer layer, and the shaft has a particularly high bending rigidity and bending strength. In this configuration, by increasing the number of central yarns or the number of single fibers focused on the central yarn in sequence, the distance between the yarns is increased and the frictional resistance generated by the contact of each yarn can be increased. The yarn is not disturbed in the resin impregnation step after forming the braid or in the taping step after the resin impregnation, so that the designed shaft can be obtained.
Further, each yarn constituting the braided layer is constituted by a fiber bundle of inorganic fibers, organic fibers and metal fibers which are impregnated with a resin in advance, or a fiber bundle of mixed materials. Since the adhesion force of the impregnating resin is added to the frictional resistance generated by the contact, compared to the case of forming a braid with yarn not impregnated with resin,
Each yarn can be easily fixed at a desired position.
[0015]
Furthermore, by making the resin content of each yarn constituting the braided layer 20% to 50% in volume ratio, the performance as a fiber reinforced plastic shaft such as bending rigidity and torsional rigidity is sufficiently exhibited. can do.
In this case, if the resin content of each yarn is less than 20% by volume, the amount of impregnated resin is insufficient with respect to the amount of reinforcing fiber. It is not preferable because delamination tends to occur.
In addition, when the resin content of each yarn is larger than 50% by volume, the amount of impregnated resin is too large with respect to the amount of reinforcing fiber, so that the bending rigidity and torsional rigidity of the cured shaft are very small. This is not preferable because it does not satisfy the performance required for a fiber-reinforced plastic shaft.
The shaft of the present invention can be arbitrarily adjusted in weight, natural frequency, bending strength, etc. by design, but the weight is 35-60 g and the natural frequency is 190-210 c. p. m. Further, by setting the bending strength at a position of 90 mm from the tip of the shaft small diameter portion side to 120 kgf or more, it is possible to obtain a fiber-reinforced plastic shaft that is lightweight but easy to swing and resistant to impact.
[0016]
【Example】
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a shaft 1 according to the present embodiment, and FIG. 2 is an enlarged explanatory view showing the structure of the assembly of the shaft 1 of FIG.
As shown in FIG. 2, the shaft 1 of this embodiment includes braided yarns a and a ′ knitted so as to have a symmetrical winding angle with respect to the shaft axis 14 that is the central axis in the longitudinal direction of the shaft 1. A braided layer formed from a central yarn b knitted to the braided yarns a and a ′ and knitted to have a winding angle of 0 ° with respect to the shaft axis is formed by laminating a plurality of layers. It has a configuration. Then, as the braid layer constituting the shaft 1 changes from the inner layer to the outer layer, the number of yarns of the braids a, a ′ and the central yarn b constituting the braid layer is sequentially increased to reduce the yarn interval. It is a shaft for a golf club made of fiber reinforced plastic that has a structure in which the gap portion e is made smaller.
[0017]
Next, a method for manufacturing a fiber reinforced plastic golf club shaft according to this embodiment will be described.
The mandrel to be used has a length of 1450 mm, a small diameter portion side tip of 4 mmφ, and a large diameter portion side tip of 14.75 mmφ.
The yarn to be used is a roving yarn (UT500: trade name of Nippon Oil Co., Ltd.) made of a carbon fiber bundle impregnated with an epoxy resin in advance. The number of single fibers focused on the yarn is 6000, the fineness of the fibers is 400 g / km, and the resin content is 25% by volume.
The yarn is braided on the mandrel by a braided string machine. In this embodiment, as shown in FIG. 2, braided yarns a and a ′ having winding angles symmetrical to the shaft axis 14 are shown. The center yarn b having a winding angle of 0 ° with respect to the shaft axis is braided into the same layer to form a braided layer, and a plurality of the braided layers are laminated. Each yarn constituting the braided layer was formed by sequentially increasing the number of braided yarns a and a ′ and the central yarn b as the inner layer changed to the outer layer.
The winding tension of the yarn at the time of braiding is 1.0 kgf / mm ² .
Table 1 shows the number of windings of the braided yarns a and a ′ and the central yarn b, the winding angle of the braided yarns a and a ′, and the yarn interval.
[0018]
[Table 1]
[0019]
Here, regarding the meaning of ABCD described in the column of the winding angle of the braid, the winding angle in the range from the tip of the mandrel small diameter portion side to 250 mm is from the position of A, 250 mm. Further, the 680 mm tip is divided into two equal parts, the small diameter part side is B, the large diameter part side is C, the range from the position of 680 mm to the large diameter part side tip is D, and the winding angle is in the range of A to D. It shows that it is changing continuously.
In the fiber reinforced plastic shaft intermediate body after the four layers of the braided layer are laminated with the above-mentioned specifications, the intervals between the yarns wound around the mandrel are closely adjacent in each layer, and the gap portion e is very small. It became a thing. In addition, the determination of the density of the thread interval is
The surface of each layer after the formation of the braid is judged visually, and the case where there is a gap portion e of about 9 mm ² or more is sparse.
[0020]
Next, the fiber reinforced plastic shaft intermediate was wound with a heat-resistant wrapping tape, heat-cured, and then the mandrel was pulled out, and the wrapping tape was removed to obtain a fiber reinforced plastic shaft molded product.
The full length of the fiber reinforced plastic shaft molded product was trimmed, finish-polished, and painted to obtain a fiber reinforced plastic shaft finished product.
[0021]
Hereinafter, a comparative example will be described.
Comparative Example 1 and Comparative Example 2
The shafts of Comparative Examples 1 and 2 are each formed by laminating a plurality of braid layers composed of a braid having a winding angle symmetrical to the shaft axis and a central yarn having a winding angle of 0 ° with respect to the shaft axis. A shaft for a fiber reinforced plastic golf club having a structure formed as described above and having a structure in which the number of each yarn in each braided layer is equal throughout the entire layer.
Next, a method for manufacturing a fiber reinforced plastic golf club shaft according to a comparative example will be described.
The mandrel, the yarn, and the winding tension of the yarn to be used are the same as those in the examples in Comparative Examples 1 and 2.
The number of windings of the braided yarn and the central yarn, the winding angle of the braided yarn, and the yarn interval are shown in Table 2 for Comparative Example 1 and Table 3 for Comparative Example 2. Note that the meaning of ABCD and the method for determining the density of the yarn interval described in the column of braided yarn winding angle are the same as in the embodiment.
[0022]
[Table 2]
[0023]
[Table 3]
[0024]
Comparative Example 1 has the same specifications as the first layer of the example (number of braided yarns and central yarns wound, winding angle of the braided yarn) until the same thickness as that of the example, and the same as the example The assembly is formed until the weight is reached. Therefore, the number of laminated layers is a five-layer structure which is one layer greater than that of the example. The interval between the wound yarns is dense in the first layer, but is sparse in the second and subsequent layers, and the gap portion becomes larger and larger as it becomes the outer layer of the shaft, and is conspicuous in the ranges C and D. It was.
In Comparative Example 2, the same number of braids and center yarns as the first layer of the example are wound, the same thickness as the example, the same weight as the example, and the yarn interval is dense. The braid angle in the range of A to D is continuously changed for each layer so as to form a braid.
The total length, weight, and diameter of the tip of the small diameter side of the finished fiber reinforced plastic shaft,
Table 4 summarizes the diameter at the tip of the large-diameter portion, yarn disturbance, natural frequency, and bending strength.
[0025]
[Table 4]
[0026]
Here, an outline of a method for measuring yarn disturbance, natural frequency, and bending strength will be described.
As for yarn disturbance, a stroke line parallel to the shaft axis is inserted in the longitudinal direction of the mandrel in advance, and at the same time as forming the shaft, the resin that has entered the stroke line is cured to form a convex on the inner side of the shaft. When the finished shaft is cut in the circumferential direction at a pitch of 10 mm and the cross section is enlarged and observed, the angle formed by the convex part and the thread cross section to be measured with respect to the shaft center is measured. The change is a disturbance of the yarn. For the present example and comparative examples 1 and 2, for the sake of simplicity, only the central thread was measured.
[0027]
The natural frequency was measured by a natural frequency measuring device shown in FIG.
The measurement method is as follows. First, the large-diameter portion side 2 of the shaft 1 is horizontally fixed by a fixing jig 4 attached to the calculation unit 15, and a predetermined weight jig 5 is fixed to the tip of the small-diameter portion side 3. . After holding the weight jig 5 by hand to sink the shaft 1 by a certain distance, the hand 1 is released to vibrate the shaft 1 and the shaft 1 blocks the infrared sensor between the light source 6 and the photoelectric cell 7 of the measuring unit 16. Was measured and converted to the number of vibrations per minute by the counter unit 8 in the calculation unit 15 and displayed on the digital display panel 9 of the display unit. The distance L1 from the fixing jig 4 to the infrared sensor between the light source 6 and the photoelectric cell 7 is 680 mm, and the weight of the weight jig 5 is 287.5 g. In this example and Comparative Examples 1 and 2, as a guideline for uniformity of bending rigidity in the circumferential direction, that is, as a guideline for quality stability, the first measured arbitrary longitudinal direction is set to 0 °, and from there, the shaft axis Rotate 90 ° around the center and measure again, and read the difference between the frequency in the 0 ° direction and the frequency in the 90 ° direction.
[0028]
As for the bending strength, as shown in FIG. 5, both ends in the length direction of the shaft test piece 10 cut to a predetermined dimension are placed on the support bases 13 and 13 ′, and the shaft test is performed by the pressure wedge 12 at a predetermined load speed. A load is applied to the central portion 11 of the piece 10 to read the breaking load. The radius of the pressure wedge 12 is 75 mm, the radius of the support bases 13 and 13 ′ is 12.5 mm, and the load speed is 20 mm / min.
E, F, G, and H shown in the column of bending strength in Table 4 represent bending strength measurement positions, E is a position 90 mm away from the tip of the shaft small diameter side 3 and F is a small shaft diameter. G means a position 175 mm away from the tip of the section side 3, G denotes a position 525 mm away from the tip of the shaft small diameter section 3, and H denotes a position 175 mm away from the tip of the shaft large diameter section 2. Further, the fulcrum distance L2 from the support bases 13 to 13 ′ is 150 mm when the bending strength measurement position is E, and 300 mm when the F, G, and H positions.
[0029]
From Table 4, comparing the example and Comparative Examples 1 and 2, the overall length, weight, diameter of the tip of the small diameter part, and diameter of the tip of the large diameter part are all the same as designed, In Example 1, the yarn was greatly disturbed, and the difference between the frequency in the 0 ° direction and the frequency in the 90 ° direction was 5c. p. m. The bending strength at each point from E to H was also weaker than that of the example. This is because the yarn interval of the fiber reinforced plastic shaft intermediate of Comparative Example 1 was not dense except for the first layer, and the yarn was displaced in the direction in which the tape tension acts during taping, and was meandering. For this reason, in the shaft of Comparative Example 1, the fiber density can be biased, or void portions where the resin has not been completely filled become voids, so that sufficient rigidity and strength cannot be realized.
[0030]
In Comparative Example 2, since the yarn interval of the fiber reinforced plastic shaft intermediate was dense, there was no yarn disturbance, and the natural frequencies in the 0 ° direction and the 90 ° direction were also constant. However, the natural frequency is 6c. p. m. And the bending strength was weak. This is because the fiber intermediate of the fiber reinforced plastic shaft of Comparative Example 2 increases the winding angle of the braided yarn, that is, increases the winding amount of the braided yarn so that the yarn interval is close. Neither bending rigidity nor bending strength was sufficient.
In comparison with the results of Comparative Examples 1 and 2, in the example, the yarn interval is increased by increasing the number of braids and center yarns sequentially from the inner layer to the outer layer, so that there is no yarn disturbance.
The natural frequencies in the 0 ° direction and 90 ° direction are also constant, and 197c. p. m. It was hard and the bending strength was sufficiently strong. Although the weight is 45 g, it can be said that the shaft has sufficient bending rigidity and bending strength and has stable quality.
[0031]
【The invention's effect】
As described above, the present invention is a fiber formed by a plurality of braid layers composed of a braid having a winding angle symmetrical to the shaft axis and a central yarn having a winding angle of 0 ° with respect to the shaft. In the shaft for a reinforced plastic golf club, each yarn constituting the assembly layer has a structure in which the number of yarns or the number of single fibers focused on the yarn is sequentially increased from the inner layer to the outer layer. Makes the thread spacing dense,
In the resin impregnation step after forming the braid, or in the taping step after resin impregnation, the frictional resistance generated by contacting each yarn can be increased.
Since the yarn is not disturbed and meandered, the degree of freedom in designing the characteristics of the fiber-reinforced plastic shaft such as bending rigidity, bending strength and torsional rigidity is improved.
[0032]
In addition, as the configuration in which the number of yarns constituting the braided layer or the number of single fibers focused on the yarn is sequentially increased from the inner layer to the outer layer, the number of central yarns or the single fibers focused on the central yarn is increased. By adopting a configuration in which the number of fibers is sequentially increased, the yarn spacing becomes dense and the frictional resistance generated by the contact of each yarn can be increased. In the resin impregnation step after forming the braid, or In the taping process after resin impregnation, the yarn is not disturbed and meandered, and it is bent without increasing the weight compared to a fiber reinforced plastic shaft with a larger thread spacing and a tighter thread spacing. Rigidity and bending strength can be increased.
The feature of the present invention to be particularly emphasized is that, in a golf club shaft formed as a braid, by increasing the number of yarns constituting the braid layer or the number of single fibers focused on each yarn, It is possible to provide a lightweight golf club shaft that satisfies the target characteristics of the golf club shaft, and has the desired properties in terms of bending strength, twist, and bending rigidity.
[Brief description of the drawings]
FIG. 1 is a front view of a fiber reinforced plastic golf club shaft according to an embodiment of the present invention.
FIG. 2 is an enlarged explanatory view showing the assembly structure of the shaft of FIG. 1;
FIG. 3 is an enlarged explanatory view showing a part of a braid layer after the second time of a golf club shaft formed by a prior art.
FIG. 4 is a top view of a natural frequency measuring device for a golf club shaft.
FIG. 5 is an explanatory diagram of a method for measuring the bending strength of a golf club shaft.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shaft 2 Large diameter part side 3 Small diameter part side 4 Fixing jig 5 Weight jig 6 Light source 7 Photoelectric cell 8 Counter unit 9 Digital display board 10 Shaft test piece 11 Center part 12 Pressure wedge 13 Support stand 13 'support stand 14 Shaft shaft 15 Calculation unit 16 Measuring unit a Braiding a 'Braiding b Central thread c Crossing portion d Crossing portion e Air gap portion L1 distance L2 Distance between fulcrums

Claims (3)

A fiber-reinforced plastic golf formed by laminating a plurality of braid layers composed of a braid having a winding angle symmetrical to the shaft axis and a central yarn having a winding angle of 0 ° with respect to the shaft. in club shaft, the yarn constituting the braid layer, in accordance becomes the outer layer from the inner layer, characterized in that sequentially increasing the number of single fibers are converged to the number or the central thread of the central yarn Golf club shaft made of fiber reinforced plastic.   2. The fiber reinforced plastic golf club shaft according to claim 1, wherein a resin content of each yarn constituting the braided layer is 20% to 50% by volume.   The shaft weighs 35-60 g and has a natural frequency of 190-210 c. p. m. 3. The fiber-reinforced plastic golf club shaft according to claim 1, wherein a bending strength at a position 90 mm from the tip of the shaft narrow diameter portion side is 120 kgf or more and 150 kgf or less.

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