JP4241416B2 - FRP shaft manufacturing method and FRP shaft - Google Patents

Description

  The present invention relates to a method for manufacturing an FRP shaft of a fiber-reinforced composite material composed of a braided layer having a braiding composition, and an FRP shaft.

  Conventionally, pipes and shafts have been manufactured from fiber reinforced plastics (FRP), which are assembled structures made of high-strength yarns such as glass fibers, carbon fibers, or nylon fibers. An FRP shaft manufactured by laminating FRP on the outer periphery of a mandrel, winding the surface with a wrapping tape, etc., heat-curing, peeling the wrapping tape, and polishing the surface is known. It is. As a typical example, a carbon shaft mixed with carbon fibers is known.

  In general, a sheet winding method and a braiding method are known for manufacturing such FRP shafts. In the sheet winding method, multiple layers of prepreg made of glass fiber or carbon fiber impregnated with epoxy resin or the like are wound into a plurality of layers to form a shaft, which is then loaded into a mold, or heat shrink tape is applied. A method of winding and curing by heating in an oven or the like is employed.

  In the braiding method, reinforcing fibers impregnated with a resin are generally wound and coated on a mandrel serving as a central axis at a predetermined orientation angle (with a braiding composition), and then heated and cured to form. Also known are a biaxially structured braid layer having an orientation angle symmetric with respect to the axial direction, and a triaxial structured braid layer having the two axes and a central thread having an orientation angle of approximately 0 °. Yes.

Furthermore, the present applicant has filed an application for a pipe manufacturing apparatus in which a plurality of braided units are composed of a plurality of braided units and a central thread can be supplied to each braider unit. (For example, see Patent Document 1)
In addition, a golf shaft having an FRP golf shaft composed of a plurality of braid layers, a biaxial braid layer on the outer layer, and a braid laminar structure on the inner side has already been filed. (For example, see Patent Document 2)
JP-A-8-284052 (page 1-6, FIG. 4) Japanese Patent No. 3169360 (page 1-4, FIG. 1)

  A golf club using the FRP shaft, for example, a carbon shaft golf club, is lightweight and useful for beginners. However, the bending rigidity and torsional rigidity of the carbon shaft is not as high as that of the steel shaft, and for the strong engineer, the bending condition of the shaft changes greatly during the swing, and the position and direction of the ball to be thrown is not stable. is there.

  Therefore, a shaft made of FRP having bending rigidity and torsional rigidity equivalent to a steel shaft used by advanced users is desired.

  Further, the FRP shaft is polished after heat-curing, but if the surface unevenness is large, the amount to be polished becomes large, which is uneconomical, and predetermined bending rigidity and torsional rigidity may not be obtained.

  The object of the present invention is to provide a manufacturing method of an FRP shaft having a laminated structure of a plurality of layers of reinforcing fibers and an FRP shaft having high bending rigidity and torsional rigidity equivalent to a steel shaft. An object of the present invention is to provide an FRP shaft manufacturing method and an FRP shaft that provide a smooth contour curve that minimizes surface irregularities.

In order to achieve the above object, the invention according to claim 1 is based on a plurality of layers of reinforcing fibers, wherein a bobbin carrier on which a bobbin on which a yarn is wound is placed travels along a raceway surface to form a composition. A method for manufacturing an FRP shaft having a laminated structure of a braided structure, wherein at least one layer of the laminated structure is a central yarn having an orientation angle of 0 ° in addition to a biaxial yarn having a symmetrical orientation angle And a bobbin carrier around which the biaxial yarn having the symmetrical orientation angle is wound on a part of the central yarn disposing layer is stopped on the raceway surface. Thus, the orientation angle of the composition yarn is set to 0 °, and a parallel portion is provided in which the orientation angles of all the yarns of the central yarn and the biaxial yarn are 0 °. .

According to the invention according to claim 1 having the above-described configuration, in addition to the biaxial yarn having a symmetrical orientation angle in at least one layer of the multilayer structure, the center in which the central yarn having the orientation angle of 0 ° is disposed. By using a laminated structure in which a yarn disposing layer is provided, a composition can be formed on a shaft having arbitrary bending rigidity and torsional rigidity. In addition, a torsional rigidity is provided by providing a parallel portion where the orientation angle of all three axes of the center yarn to be composed and the biaxial yarn is 0 ° in a part of the central yarn arrangement layer. A shaft made of FRP with improved can be manufactured.

The invention according to claim 2 is a braiding composition in which the orientation angle in the biaxial assembly composition having a symmetrical orientation angle is linearly controlled so that the thickness of each laminated portion is linearly displaced over the entire layer. And it is set as the structure provided with the thickness distribution smoothly displaced to linear form.

According to the invention according to claim 2 having the above-described configuration, it is possible to compose an FRP shaft having a predetermined thickness and a predetermined bending rigidity while appropriately controlling the orientation angle of each layer. The amount of polishing after composition can be reduced, and an FRP shaft having a predetermined thickness and bending rigidity can be produced.

The invention according to claim 3 is an FRP shaft manufactured by the method for manufacturing an FRP shaft according to claim 1 or 2, wherein at least one layer among the plurality of laminated structures has a symmetrical orientation angle. In addition to the biaxial yarns having a central yarn disposing layer for disposing a central yarn having an orientation angle of 0 °, a part of the central yarn disposing layer has the symmetrical orientation angle 2 A parallel portion is provided in which the orientation angle of the shaft yarn is 0 °, and the orientation angle of all the yarns of the central yarn and the biaxial yarn is 0 °.

According to the invention according to claim 3 having the above-described configuration, the central yarn disposing layer provided in at least one layer among the plurality of laminated structures is provided with the parallel portion in which all the yarns to be composed have an orientation angle of 0 °. Thus, an FRP shaft having a predetermined value of bending rigidity and torsional rigidity at an arbitrary position can be obtained.

The invention according to claim 4 is characterized in that the volume fraction of the reinforcing fibers is 60% or more.

According to the invention which concerns on Claim 4 which has said structure, the bending rigidity and torsional rigidity of a shaft can be improved further.

  According to the present invention, a laminated structure of a multi-layered assembly is laminated while controlling the orientation angle of each layer, and a parallel portion in which the orientation angles of all the threads are 0 ° is provided in a predetermined layer. Thus, the FRP shaft manufacturing method and the FRP shaft can be obtained which has a high bending rigidity and torsional rigidity of the shaft and has a smooth outer shape curve that minimizes surface irregularities.

  A manufacturing method of an FRP shaft having a laminated structure of a plurality of layers of reinforcing fibers and an FRP shaft, which has high shaft bending rigidity and torsional rigidity, and has a smooth outline curve that minimizes surface irregularities In order to obtain an FRP shaft manufacturing method and an FRP shaft, a plurality of layers having a braiding composition while linearly changing and controlling the orientation angle in a biaxial assembly composition having a symmetrical orientation angle. This is realized by providing a laminated structure of braids and providing parallel portions where the orientation angle of the yarns composed in at least one layer is 0 °.

  Hereinafter, the manufacturing method of the shaft made from FRP and the Example of the shaft made from FRP which concern on this invention are demonstrated based on FIGS. 1-8.

  First, based on FIG. 7 and FIG. 8, one structural example of the braider which manufactures the shaft made from FRP which concerns on this invention is demonstrated. The braider BR is configured by sequentially arranging a supply conveyor unit 11, a braider body unit 13, a wrapping unit 14, a cutter unit 15, and a discharge conveyor unit 16 in series.

  The supply conveyor unit 11 continuously supplies the mandrel M to the braider main body unit 13 that performs the braiding composition by the conveyor 11a, and the supply conveyor unit 11 includes a mandrel stocker 12 provided on the side of the supply conveyor unit. The mandrels M stocked in the are sequentially supplied.

  In the case of this example, the mandrel M is composed of a rod-shaped body having a different cross-sectional area, but it can of course be composed of a rod-shaped body having a uniform thickness.

  While the mandrel M supplied to the braider body 13 is conveyed in the downstream direction, the plurality of braider units 20, 20.. A thread or string-like prepreg impregnated with thermoplastic fibers (for example, glass fibers or carbon fibers) is braided and then transferred to the wrapping section 14, and then the tape T attached to the wrapping device 31 is attached. Wrapping work is performed. Moreover, at the time of braiding composition, the center yarn y which is a reinforcement fiber can be drawn out from the center yarn supply part 17, and can be supplied to each braider unit 20, and it can be set as the braiding composition of the triaxial structure containing the center yarn y.

  The braiding composition Br that has been subjected to the braiding composition and the lapping operation is completed is sent to the cutter unit 15, and the yarn Y, the center yarn y, and the tape T are cut by the cutting device 15 </ b> A and transferred to the discharge conveyor unit 16. It is discharged by the discharge arm 16A. In the discharged braiding composition Br, the resin component impregnated in the yarn is cured by heating in an oven or heating / pressurization in a pressure vessel. Thereafter, the mandrel M is extracted to form a pipe-shaped FRP shaft.

  As shown in FIG. 7, the braider body 13 is provided with a plurality of braider units 20. The braider unit 20 has a center hole 21a through which the mandrel M passes, and a raceway surface 21 formed in a substantially disk shape is installed vertically, and a plurality of bobbin carriers 23, 23. Is mounted so as to be movable on the track surface 21.

  The yarn Y is pulled out from the bobbin carrier 23 around which the yarn Y is wound, and is fed out to a portion of the narrowing guide 24 including the annular yarn guide 25. Further, the central yarn y fed out from the bobbin Bb of the central yarn supply unit 17 is guided to the annular yarn guide 25 and the narrowing guide 24 through the cylindrical body 22 erected on the raceway surface 21. The diaphragm guide 24 performs centering of the mandrel M having a braiding composition while passing through the center hole 21a.

  Then, in the process in which the mandrel M supplied from the supply conveyor unit 11 enters the braider body 13 and moves downstream, portions of the annular yarn guide 25 and the squeezing guide 24 that are the braiding composition work portions of each braider unit 20 The braiding composition is configured in order from the upstream braider unit 20. In this case, the bobbin carrier 23 performs the braiding composition while moving on the raceway surface 21, but the braider unit 20 is configured so that the moving speed of the bobbin carrier 23 can be freely changed individually. For example, the mandrel M The blade angle (orientation angle) can be changed between the front end portion and the rear end portion, or can be changed in each layer, and the physical characteristics of the completed pipe-shaped member can be freely set.

  After the braiding composition work is performed, the mandrel M enters the wrapping unit 14, the tape T is wrapped by the wrapping device 31, and the yarn Y, the central yarn y, and the tape T are cut by the cutter unit 15. It is configured to be discharged.

  FIG. 1A shows a composition structure having a portion in which the orientation angle of the triaxial yarn including the central yarn is 0 °, and the biaxial shaft having the symmetrical orientation angle α composed of the yarn Y. In addition to the braid composition, in the triaxial braid composition having the center yarn y having an orientation angle of 0 °, a parallel portion H in which the orientation angle of all three axes is 0 ° is provided by the method described above. be able to.

  The assembly of the laminated structure shown in FIG. 1B shows a FRP shaft having a four-layer structure, and the inner layer 1 is composed on the mandrel M so that the orientation angle is larger than the other layers. The layers 2 and 3 and the outer layer 4 are composed. In addition, in addition to the biaxial braid composition composed of the yarn Y having a bilaterally symmetric orientation angle, the layer 3 is provided with a central yarn y having an orientation angle of 0 ° to obtain a triaxial braid composition. It is.

  Here, the orientation angle α will be described. The orientation angle is the angle between the shaft axis and the assembly, the small orientation angle is the angle where the assembly is nearly parallel to the shaft axis (close to 0 °), and the large orientation angle is perpendicular to the shaft axis. An angle that approaches the direction. Further, here, a braid having an orientation angle symmetrical to the shaft axis is used.

  Each layer uses a carbon fiber or the like impregnated with a thermosetting resin (for example, an epoxy resin) as a prepreg, and each layer is formed by braiding by the above-described operation of the braiding composition. Moreover, it can also be set as the structure which inserted the center thread | yarn in the axial direction (orientation angle 0 degree) as each composition structure, and can be set as the composition structure which further improves bending rigidity. Further, instead of the thermosetting resin, a thermoplastic resin (for example, polyethylene resin) can be employed as the molding resin.

  At this time, the bobbin carrier winding the biaxial yarn having the symmetrical orientation angle is stopped on the raceway surface, so that the orientation angle of the triaxial yarn including the central yarn y is 0. If the parallel portion H is provided, the bending rigidity and torsional rigidity of the shaft can be further changed.

  As described above, the orientation angle α can be changed by changing the moving speed of the bobbin carrier 23 on the track surface 21. Further, by setting the moving speed to 0, that is, by stopping the bobbin carrier 23 on the track surface 21, the orientation angle α can be set to 0 °. Even when the orientation angle α is 0 °, the composition structure can be maintained by laminating the next braided layer thereon or winding a wrapping tape.

  In addition, in the FRP shaft provided with the parallel portion where all the orientation angles of the triaxial yarns including the central yarn y are 0 °, the bending rigidity and the torsional rigidity of the shaft are improved. It was confirmed.

  FIG. 2 shows the experimental results. FIG. 2 (a) shows a conventional braid configuration, from the inside, the first layer is composed of 16 general-purpose carbon fibers A16, and the second layer is composed of 8 highly elastic carbon fibers B and the center. A braid of 8 yarns C, a triaxial braid layer of 16 high-elastic carbon fibers and 8 central yarns C in the third layer, and a general-purpose carbon fiber D16 in the fourth layer of the outermost layer It is the shaft of the structure which has arrange | positioned the layer. (B) shows the product of the present invention. From the inside, the first layer is composed of 16 general-purpose carbon fibers A, the second layer is composed of 8 highly elastic carbon fibers B, and the third layer is composed of layers. Eight central yarns C and eight braids of the same quality as the central yarn C (with an orientation angle of 0 °), a total of 16 uniaxial layers (parallel portions), and the fourth layer of 16 highly elastic carbon fibers B The shaft is composed of a braid layer of 16 general-purpose carbon fibers D in the braid layer and the fifth layer. (C) shows the dimensions and weight of the obtained shaft, and the torsion angle θ when the torsion test is performed.

  In both the conventional product and the product of the present invention, the total number of yarns constituting the composition is 72, and the size and weight of the manufactured shaft are the same. For example, the outer diameter of the small diameter portion a is 9.24 mm and 9.21 mm, the outer diameter of the large diameter portion d is 15.96 mm and 15.93 mm, and the weight is 83.7 g (conventional product) and 83. 16 g (product of the present invention). However, when the torsion angle θ was measured when one end of the shaft was fixed and the moment load W was applied to the other end side, it was 4.4 ° with the conventional product, but 3.9 ° with the product of the present invention. became.

  That is, when the same torsional moment is applied, the torsional angle is small in the product of the present invention, and the torsional angle θ is reduced by 0.5 ° with the same shaped shaft. For this reason, it has been clarified that the FRP shaft provided with the parallel portions in which all the orientation angles of the triaxial yarns including the central yarn y are 0 ° has high torsional rigidity. As described above, in the conventional product, the center yarn C is 16 in total in the second layer and 8 in the third layer and 8 in the third layer, and in the present invention product, a total of 16 parallel portions are provided in the third layer. The yarn density is the same. Nevertheless, the difference in torsional rigidity is assumed to be due to the difference in the braid structure.

  When a person plays golf, the golf club is swung and the head 8 is caused to collide with the ball by the centrifugal force so as to fly the ball to a desired position. For that purpose, it is important that the bending rigidity and torsional rigidity of the shaft have predetermined values.

  When the bending rigidity and the torsional rigidity are not within the predetermined ranges, when the ball is swung to hit the ball, the bending condition of the shaft greatly changes, and the position of the ball to be thrown is not stable. Further, it sometimes affects the swing, and affects the feeling (stability, etc.) when the golfer swings the golf club. A professional golfer with a high head speed and a large degree of shaft deformation and an advanced player can easily feel the shaft deformation. In particular, since the deformation of the shaft at impact affects the quality of the hit ball, it is desirable to suppress the deformation of the shaft and stabilize the hit ball.

  For this purpose, even FRP golf shafts require bending rigidity and torsional rigidity equivalent to steel shafts with stable high bending rigidity and torsional rigidity, and the torsion angle θ is reduced by 0.5 °. It can be said that the shaft has a torsional rigidity similar to that of a conventional steel shaft.

  Moreover, the FRP control shaft which demonstrates arbitrary torsional rigidity by making the yarn which comprises the biaxial braid composition which has the symmetrical orientation angle (alpha) left-right originally into a parallel part with an orientation angle of 0 degrees only in a predetermined part. Can be manufactured, and there is no need to newly provide another central thread. That is, the yarn Y provided for the braiding composition can be formed as a central yarn, which is efficient and can be set with desired torsional rigidity and bending rigidity.

  FIG. 3 shows the orientation angle of each layer set when composing the conventional product and the product of the present invention. The first innermost layer has an orientation angle of 10 ° (small diameter portion a) to 60 ° (large diameter portion d), and the outermost layer portion has an orientation angle of 6 ° to 10 °. Has been.

  Also, a braid layer and a center yarn layer with an orientation angle of 9 ° to 50 ° are arranged on the second layer and the third layer of the conventional product, and inside and outside of the third layer with an orientation angle of 0 ° of the present invention product. A braid having an orientation angle of 9 ° to 60 ° is formed in the second layer and the fourth layer.

  As described above, the total number of yarns of the braided layer having the orientation angle and the parallel portion (including the center yarn) of the orientation angle of 0 ° was equalized to obtain an FRP shaft having an equivalent outer diameter. A clear difference in torsional rigidity was observed, demonstrating that the method of manufacturing a shaft according to the present invention is effective.

  The composition structure 5 shown in FIG. 4 (a) is a triaxial assembly composition having a central thread, a composition structure in which the biaxial orientation angle is reduced, and the orientation angle α1 for composing the yarns Y1 and Y2 is When molding is performed in a state where the orientation angle is small, the prepreg fibers are molded in the opened state, and the upper and lower fibers are well overlapped with each other, so that delamination hardly occurs. That is, since the connection between the upper and lower layers becomes stronger, the shear strength between the layers becomes stronger. Therefore, if a layer with a small orientation angle is provided, the bending rigidity of the FRP shaft to be molded can be improved.

  Moreover, since it is set as the structure provided with the center yarn y whose orientation angle is 0 degree, the bending rigidity of the axial direction of the said shaft can further be improved.

  Furthermore, when a parallel portion H is provided in which the orientation angle of a biaxial yarn having a symmetrical orientation angle α1 is 0 °, and the orientation angle of all the three axis yarns including the central yarn y is 0 °, The bending rigidity and torsional rigidity of the shaft are further improved.

  The composition structure 6 shown in FIG. 4 (b) is a biaxial assembly composition that does not have a central thread, and is a composition structure in which the orientation angle of the two axes is increased, and the yarns Y1 and Y2 are composed. In the configuration in which the orientation angle α3 is large, the prepreg fibers to be laminated can be densely formed, and the strength is increased in the radial direction of the shaft or pipe, so that the tube strength can be improved. Therefore, it is desirable to provide the layer having a large orientation angle in the inner layer portion of the shaft.

  Furthermore, if the parallel portion H in which the orientation angle of the biaxial yarn having a symmetrical orientation angle α3 is 0 ° is provided, the bending rigidity and torsional rigidity of the shaft can be improved.

  Moreover, in order to improve the delamination strength after composition, the reinforcing fiber and the resin impregnated in the fiber may be appropriately selected and combined. However, even in this case, it is possible to further increase the delamination strength in consideration of the orientation angle during composition.

  In addition, the orientation angle of the inner layer is increased, the orientation angle of the intermediate layer and the outer layer is decreased, and the thickness of each stacked portion is controlled to be linearly displaced (also referred to as linear control). In other words, the biaxial orientation angle of the braiding composition was controlled so as to be linearly changeable over the entire layer, and the manufacturing method was such that the axial thickness distribution of the manufactured shaft was smoothly linear.

  The above-described control refers to the orientation angle when forming each layer and the thickness of the layer when laminated by the orientation angle, and by calculating the elastic modulus obtained at that time, the predetermined thickness and elastic modulus The braiding composition is performed while controlling the orientation angle so that the orientation angle can be obtained, and a so-called laminated beam theory is used to determine an orientation angle that exhibits a predetermined thickness and elastic modulus, and the center yarn y A three-axis braiding composition can be performed.

  Here, with reference to FIG. 5 and FIG. 6, the FRP shaft that is braided using the laminated beam theory and the blade thickness calculation formula will be described. FIG. 5 shows the thickness distribution of each layer of the laminated structure in which the thickness is changed and controlled linearly, and FIG. 6 shows the theoretical value and the actual measurement value of the bending stiffness by the laminated beam theory.

  As shown in FIG. 5, when the innermost layer L1, the intermediate layer L2, and the outermost layer L3 are laminated on the mandrel M having different diameters in the length direction of the shaft, the thickness F1 of the innermost layer L1 and the intermediate layer L2 The thickness F2 and the thickness F3 of the outermost layer L3 are controlled so as to be smoothly displaced linearly (also referred to as linear control).

The theoretical value and actual measurement value of the bending rigidity EI at that time are shown in FIG. Here, the bending rigidity EI is a value obtained by applying a predetermined load to a predetermined position in the length direction and measuring the amount of deflection at that time, and the unit is kg · mm ^2. It is. In the figure, 10 ⁶ kg · mm ² is indicated as E + 6.

  The actual measurement value E1 shown by the solid line in the figure is substantially equivalent to the theoretical value E0 shown by the two-dot chain line, and it is confirmed that this shaft has the desired bending rigidity. For example, the optimization of the bending stiffness of a golf shaft can be obtained by taking into account the player's swing and determining the bending stiffness of the shaft that gives the maximum initial velocity to the ball using the flexural vibration generated on the shaft. The trajectory and drop point during the flight of the ball can also be obtained by calculating the ball speed, spin rate and launch angle from the bending rigidity of the shaft. That is, according to this manufacturing method, it is possible to obtain an FRP golf shaft having optimum bending rigidity according to the physique and physical strength of each player.

  In addition, the reinforcing fiber-containing volume ratio in general sheet winding is 50 to 55%, which is due to the reinforcing fiber-containing volume ratio at the time of the base material, and it is difficult to change the volume ratio. However, in the present embodiment, the volume ratio can be increased to 65% by winding closely during the braiding composition and changing the wrapping tension. That is, the reinforcing fiber-containing volume ratio can be controlled between 50 and 65%.

  If the reinforcing fiber-containing volume fraction is increased, the bending rigidity and torsional rigidity of the shaft are increased, and a high-quality FRP shaft can be obtained. For this purpose, a multi-layered laminated structure in which a braiding composition is controlled while linearly changing the orientation angle in a biaxial assembly composition having a symmetric orientation angle over all layers, and the orientation angle is at least in one layer. A manufacturing method in which a center yarn of almost 0 ° is disposed, and a biaxial portion having a symmetrical orientation angle and a parallel portion in which all orientation angles of the three-axis yarn including the central yarn are 0 ° are provided. Further, by setting the reinforcing fiber-containing volume ratio to 60% or more, a high-quality FRP golf shaft can be obtained.

It is a schematic diagram which shows the laminated structure which concerns on this invention, Comprising: (a) is a composition structure provided with the parallel part in which the orientation angle of the triaxial thread | yarn including a center thread | yarn becomes 0 degree, (b) is 3 It is a schematic explanatory drawing of the FRP shaft of a layer structure. FIG. 2 is a list showing a laminated structure, where (a) shows a laminated structure of a conventional product, (b) shows a laminated structure of a product of the present invention, and (c) shows physical properties of the product. It is a list which shows the orientation angle of each layer set when composing a conventional product and this invention product. It is the schematic explaining an orientation angle, (a) is a triaxial assembly composition including a center thread | yarn, and is a schematic diagram with a small biaxial orientation angle, (b) is a biaxial orientation angle. It is a schematic diagram of a large braid composition. It is a graph which shows the thickness distribution of each layer of the laminated structure which changed and controlled thickness linearly. It is a graph which shows the theoretical value and measured value of bending rigidity by a laminated beam theory. It is a side view which shows the braider unit part of a braider machine. It is a whole side view of a braider machine.

Explanation of symbols

21 Track surface 23 Bobbin carrier BR Braider Bb Bobbin EI Bending rigidity H Parallel part M Mandrel Y Thread y Center thread α Orientation angle θ Twist angle

Claims (4)

A method of manufacturing an FRP shaft having a laminated structure of a plurality of layers of reinforcing fibers, in which a bobbin carrier on which a bobbin on which a yarn is wound is placed is run along a raceway surface. ,
At least one layer of the laminated structure is provided with a central yarn disposing layer for disposing a central yarn having an orientation angle of 0 ° in addition to biaxial yarns having a symmetrical orientation angle,
By stopping the bobbin carrier around which the biaxial yarn having the symmetrical orientation angle is wound on a part of the central yarn arrangement layer on the raceway surface, the orientation angle of the composition yarn is 0. A method for manufacturing a shaft made of FRP, characterized in that a parallel portion is provided in which the orientation angle of all the yarns of the central yarn and the biaxial yarns is 0 °. The braiding composition is smoothly linearized by linearly controlling the orientation angle in the biaxial assembly composition having the symmetrical orientation angle so that the thickness of each laminated portion is linearly displaced over the entire layer. The manufacturing method of the shaft made from FRP according to claim 1, wherein the structure has a thickness distribution that is displaced. An FRP shaft manufactured by the FRP shaft manufacturing method according to claim 1 or 2 ,
In addition to the biaxial yarn having a bilaterally symmetric orientation angle, at least one layer of the plurality of laminated structures includes a central yarn disposing layer for disposing a central yarn having an orientation angle of 0 °
All the yarn orientations of the central yarn and the biaxial yarn are set to a part of the central yarn disposing layer and the orientation angle of the biaxial yarn having the symmetrical orientation angle is 0 °. A shaft made of FRP, characterized in that a parallel portion having an angle of 0 ° is provided. The FRP shaft according to claim 3, wherein the volume fraction of the reinforcing fibers is 60% or more.

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