Shaft and manufacturing method thereof

Abstract

To reduce the weight of a shaft.SOLUTION: A shaft 1 made of a fiber-reinforced resin contains at least a weight reduction layer 2 comprising the fiber-reinforced resin. The weight reduction layer 2 contains multiple hollow parts 3 extending in a shaft axial direction, The multiple hollow parts 3 are mutually separated and arranged in a shaft peripheral direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to shafts and methods of manufacturing the same. [Background technology]

[0002] In recent years, shafts made of fiber-reinforced resin have been used in fishing rods, golf clubs, rackets, and various other sports equipment. To improve the operability of these equipment, there is a demand for lighter shafts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-163691 Summary of the Invention [Problem to be solved by the invention]

[0004] A fiber-reinforced resin shaft is a composite of reinforcing fibers and resin. In order to reduce the weight of the shaft, attempts have been made to reduce the resin content. However, when considering the moldability of the shaft, there is a natural limit to how much the resin content can be reduced.

[0005] The present disclosure has been devised in view of the above circumstances, and has as its main object to provide a shaft that can be made lighter. [Means for solving the problem]

[0006] The present disclosure relates to a shaft made of fiber-reinforced resin, which includes at least a lightweight layer made of fiber-reinforced resin, the lightweight layer including a plurality of hollow portions extending in the axial direction of the shaft, the plurality of hollow portions being spaced apart from one another and arranged circumferentially of the shaft. [Effects of the Invention]

[0007] The shaft of the present disclosure is lightweight due to the adoption of the above configuration. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view of the shaft of the present embodiment. [Figure 2] FIG. 2 is a partial perspective view of a lightweight layer made of sheet material before molding. [Figure 3] FIG. 2 is a partial cross-sectional view of a lightweight layer. [Figure 4] FIG. 10 is a partial cross-sectional view of a lightweight layer according to another embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a shaft according to another embodiment. [Figure 6] FIG. 2 is a development view showing the arrangement of sheet materials that constitute the shaft of the present embodiment. [Figure 7] FIG. 10 is a development view showing the arrangement of sheet materials constituting a shaft of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The specific configurations shown in the embodiments and drawings are for the purpose of understanding the contents of the present disclosure, and the present disclosure is not limited to the specific configurations shown. Furthermore, in multiple embodiments, the same or common elements are designated by the same reference numerals throughout the specification, and redundant explanations will be omitted.

[0010] 1 is a cross-sectional view of a fiber-reinforced resin shaft 1 according to this embodiment. The shaft 1 according to this embodiment is configured as a golf club shaft. In other aspects, the shaft 1 may be configured as a fishing rod, various sports equipment, or the like. The shaft 1 according to this embodiment is configured, for example, in the shape of a pipe having a circular outer circumferential surface 1A and a circular inner circumferential surface 1B.

[0011] As shown in FIG. 1, the shaft 1 includes at least one lightweight layer 2 made of fiber reinforced resin.

[0012] The lightweight layer 2 of this embodiment includes a plurality of hollow portions 3 extending in the shaft axial direction. The shaft axial direction refers to the longitudinal direction of the shaft 1. Therefore, the hollow portions 3 extending in the shaft axial direction refer to elongated cavities in the shaft axial direction. The hollow portions 3 may be formed over the entire range of the shaft 1 in the shaft axial direction, or may be formed partially. Furthermore, the plurality of hollow portions 3 are arranged spaced apart from one another in the circumferential direction of the shaft. Such hollow portions 3 reduce the weight of the lightweight layer 2, thereby enabling the weight of the shaft 1 to be reduced.

[0013] It is desirable that the lightweight layer 2 extend continuously around the shaft circumferentially for at least one revolution. This further reduces the weight of the shaft 1. The lightweight layer 2 of this embodiment is formed of a single layer extending continuously around the shaft circumferentially. In another embodiment, as shown in FIG. 5, multiple lightweight layers 2 may be laminated in the radial direction of the shaft.

[0014] The lightweight layer 2 of this embodiment is formed by a sheet material that defines an outer surface 2A in the shaft radial direction and an inner surface 2B in the shaft radial direction and extends in an annular shape along the shaft circumferential direction. Both the outer surface 2A and the inner surface 2B of the lightweight layer 2 are formed in an annular shape along the shaft circumferential direction.

[0015] Figure 2 shows a partial cross-sectional view of the sheet material 20 before the lightweight layer 2 is molded into the shaft 1. In Figure 2, the symbol A is linear, but indicates the direction that will become the circumferential direction of the shaft when this sheet material 20 is molded into the shaft 1. Also, in Figure 2, the symbol B indicates the direction that will become the axial direction of the shaft when this sheet is molded into the shaft 1.

[0016] 1, each cavity 3 is located between the outer surface 2A and the inner surface 2B of the lightweight layer 2. In this embodiment, the multiple cavities 3 are arranged substantially evenly in the circumferential direction of the shaft.

[0017] 1, the maximum diameter d of each hollow portion 3 is not particularly limited, but is set to, for example, 0.01 mm or more, preferably 0.02 mm or more, and more preferably 0.1 mm or more from the viewpoint of reducing the weight of the shaft 1. Furthermore, in order to maintain the durability of the shaft 1, the maximum diameter d is set to, for example, 2.0 mm or less, preferably 1.5 mm or less, and more preferably 1.0 mm or less.

[0018] 1, the arrangement pitch p of each hollow portion 3 in the circumferential direction of the shaft is not particularly limited, but from the viewpoint of reducing the weight of the shaft 1, it may be, for example, 5 times or less, and preferably 2 times or less, the maximum diameter d of each hollow portion 3. Furthermore, in order to maintain the durability of the shaft 1, the arrangement pitch p of each hollow portion 3 may be, for example, 20 times or more, preferably 30 times or more, and more preferably 50 times or more, the maximum diameter d of each hollow portion 3.

[0019] 1, the cross-sectional shape of the hollow portion 3 is not particularly limited, and a circular or polygonal shape is preferable. In order to avoid stress concentration in the hollow portion 3 when the shaft 1 is in use, it is desirable that the cross-sectional shape of the hollow portion 3 be configured with a curve.

[0020] The weight-saving layer 2 is formed as a composite of reinforcing fibers and resin (matrix resin).

[0021] Carbon fibers are particularly preferred as reinforcing fibers because they are lightweight and have high strength. In addition to carbon fibers, glass fibers, graphite fibers, aramid fibers, silicon carbide fibers, alumina fibers, boron fibers, aromatic polyamide fibers, aromatic polyester fibers, ultra-high molecular weight polyethylene fibers, etc. may also be used as reinforcing fibers.

[0022] The resin may be, for example, a thermosetting resin or a thermoplastic resin. As the thermosetting resin, for example, an epoxy resin is preferred in terms of strength and rigidity. Other than the epoxy resin, for example, unsaturated polyester resin (vinyl ester resin), phenol resin, melamine resin, urea resin, diallyl phthalate resin, polyurethane resin, polyimide resin, silicon resin, etc. can be used alone or in combination. Furthermore, as the thermoplastic resin, for example, polyamide resin such as nylon 6 or nylon 12 is preferred because of its excellent moldability. Other than these, saturated polyester resin, polycarbonate resin, ABS resin, polyvinyl chloride resin, polyacetal resin, polystyrene resin, polyethylene resin, polyvinyl acetate resin, AS resin, methacrylic resin, polypropylene resin, fluororesin, etc. can be used alone or in combination.

[0023] As shown in Figure 3, in one example of a composite, the reinforcing fiber may be short fiber f1. The short fiber f1 may be randomly arranged in the matrix resin R, or may be oriented in a specific direction. In a preferred embodiment, the short fiber f1 is desirably oriented along the axial direction of the shaft.

[0024] The diameter of the short fibers f1 is not particularly limited, but is preferably in the range of 1 to 50 μm, for example. The length of the short fibers f1 is not particularly limited, but is preferably in the range of 100 to 3000 μm, for example. The aspect ratio of the short fibers f1, which is the length / diameter ratio, is preferably in the range of 10 to 500, for example.

[0025] Fig. 4 shows another embodiment of the composite. As shown in Fig. 4, the reinforcing fibers may include long fibers f2 formed into a hollow pipe shape surrounding the cavity 3, together with or instead of the short fibers f1. In the example of Fig. 4, the long fibers f2 are woven into a pipe shape. Such long fibers f2 not only maintain the shape of the cavity 3 but also help to increase the bending rigidity, torsional rigidity, etc. of the shaft 1.

[0026] 1, in the shaft 1 of this embodiment, the lightweight layer 2 forms, for example, an intermediate layer in the radial direction of the shaft. In other words, layers other than the lightweight layer are disposed inside and outside the lightweight layer 2. This embodiment helps to maintain the strength of the shaft 1.

[0027] In the shaft 1 of this embodiment, a bias layer 6 is disposed radially inward of the lightweight layer 2. The bias layer 6 of this embodiment is made of at least one prepreg in which reinforcing fibers (long fibers f2) are oriented at an angle of 45°±15° relative to the axial direction of the shaft. In a preferred embodiment, the bias layer 6 is formed, for example, by laminating a plurality of prepregs. The prepregs are laminated so that the reinforcing fibers intersect with each other. Such a bias layer 6 can improve the torque (torsional rigidity) of the shaft 1, and therefore helps to stabilize the direction of a hit ball when constructed as a golf club.

[0028] In addition, the shaft 1 of this embodiment has a straight layer 5 disposed radially outward of the lightweight layer 2. The straight layer 5 of this embodiment is made of at least one prepreg in which reinforcing fibers are oriented at an angle of 0°±5° relative to the axial direction of the shaft. In a preferred embodiment, the straight layer 5 is formed, for example, from a single prepreg. Such a straight layer 5 improves the bending rigidity of the shaft 1 and helps to improve the durability of the shaft 1 when constructed as a golf club.

[0029] Next, a method for manufacturing the shaft 1 of this embodiment will be described. The manufacturing method of this embodiment includes a first step, a second step, and a third step.

[0030] The first step is to prepare a sheet material 20 for the lightweight layer 2. As shown in Fig. 2, when molded, this sheet material 20 includes an outer surface 2A in the shaft radial direction, an inner surface 2B in the shaft radial direction, and a plurality of cavities 3 arranged therebetween.

[0031] FIG. 6 shows a development view of prepared sheet materials, etc. In this example, a shaft 1 is formed from sheet materials s1 to s8. In FIG. 6, the symbol Ls corresponds to the axial length of the shaft 1, with the right side corresponding to the tip end and the left side corresponding to the butt end. In this example, the total shaft length Ls is 1168 mm.

[0032] The developed view also shows the sheet materials constituting the shaft 1 in order from the radially inner side of the shaft 1. Therefore, the sheets are wound around the mandrel in order, starting from the top of the developed view. Furthermore, this developed view shows not only the winding order of each sheet, but also the arrangement of each sheet in the axial direction of the shaft. For example, the end of the first sheet material s1 is located at the tip end. The angle indicated to the left of each sheet material s1 to s8 or on the sheet itself indicates the orientation angle of the reinforcing fibers contained in that sheet material with respect to the axial direction of the shaft. All of the reinforcing fibers are carbon fibers.

[0033] In this embodiment, the sheet materials s1 and s5 to s8 are straight prepregs. In the straight prepregs, the reinforcing fibers are oriented at an angle of 0°±5° relative to the shaft axial direction, and form the above-mentioned straight layer 5. In this embodiment, the sheet materials s2 and s3 are bias prepregs. In the bias prepregs, the reinforcing fibers are oriented at an angle of 45°±15° relative to the shaft axial direction, and form the above-mentioned bias layer 6.

[0034] Furthermore, in this embodiment, the sheet material s4 is the sheet material 20 that constitutes the lightweight layer 2. As shown in FIG. 4, this sheet material s4 contains short fibers f1 made of carbon fiber and long fibers f2 formed into a pipe shape, and before molding, the maximum diameter d of the hollow portion 3 was 0.2 mm and the arrangement pitch p was 1 mm (p / d=5). The thickness of the sheet material 20 was approximately 0.5 mm. The long fibers f2 were woven into a tubular shape with a twill weave oriented in two directions, the axial direction and the circumferential direction of the shaft.

[0035] The matrix resin of each sheet material is an epoxy resin.

[0036] The second step is a step of winding the sheet materials s1 to s8 in an annular shape in the circumferential direction of the shaft. Typically, the second step is performed by sequentially winding the sheet materials s1 to s8 around a mandrel (core metal). Thereafter, it is desirable to fasten the sheet materials with wrapping tape or the like, as necessary.

[0037] In the third step, the sheet material wound together with the mandrel is heated in a mold, whereby the matrix resin is hardened and a pipe-shaped shaft 1 can be produced (Example).

[0038] For comparison, a shaft was manufactured using the sheet materials shown in Figure 7 (Comparative Example). In this example, shaft 1 is formed from first to ninth sheet materials s1 to s9. The example in Figure 7 differs from the example in Figure 6 in that the fourth sheet is a straight prepreg rather than a lightweight layer, and that three straight prepregs are used over the entire length of the shaft, but otherwise is the same as the developed view in Figure 6.

[0039] The Example shaft was approximately 1.3 g lighter than the Comparative Example shaft. Furthermore, when the three-point bending strength of the Example shaft and the Comparative Example shaft was compared, they showed essentially the same performance. Furthermore, the same metal wood-type golf club head was attached to each shaft, and golf balls were struck approximately 3,000 times at a head speed of 45 m / s. No damage was observed in either shaft, demonstrating good durability.

[0040] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above specific disclosure, and can be implemented with various modifications within the scope of the technical idea described in the claims.

[0041] [Note] The present disclosure includes the following aspects.

[0042] [Disclosure 1] A shaft made of fiber reinforced resin, At least a lightweight layer made of fiber reinforced resin, the lightweight layer includes a plurality of cavities extending in the shaft axial direction, The plurality of cavities are spaced apart from one another in the circumferential direction of the shaft. shaft. [Disclosure 2] The shaft according to Disclosure 1, wherein the lightweight layer is continuous around the shaft for at least one revolution. [Disclosure 3] The shaft according to Disclosure 1 or 2, wherein the lightweight layer is a sheet-like body that defines an outer surface in the shaft radial direction and an inner surface in the shaft radial direction and extends annularly along the shaft circumferential direction. [Disclosure 4] The shaft according to any one of Disclosures 1 to 3, wherein the lightweight layer is a composite of reinforcing fibers and resin. [Disclosure 5] The shaft of Disclosure 4, wherein the reinforcing fibers include short fibers. [Disclosure 6] The shaft according to Disclosure 4 or 5, wherein the reinforcing fibers include pipe-shaped fibers surrounding the hollow portion. [Disclosure 7] The shaft according to any one of Disclosures 1 to 6, which is a golf club shaft. [Disclosure 8] A shaft as described in Disclosure 7, which has a bias layer on the radially inner side of the lightweight layer in which reinforcing fibers are oriented at an angle of 45°±15° relative to the axial direction of the shaft. [Disclosure 9] A shaft as described in Disclosure 7 or 8, comprising a straight layer on the radial outside of the lightweight layer in which reinforcing fibers are oriented at an angle of 0°±5° relative to the axial direction of the shaft. [Disclosure 10] A method for manufacturing a shaft according to any one of Disclosures 1 to 9, a first step of preparing the lightweight layer in the form of a sheet material, the lightweight layer including an outer surface in the shaft radial direction, an inner surface in the shaft radial direction, and the plurality of cavities disposed therebetween; a second step of winding the sheet material annularly around the shaft; A method for manufacturing a shaft. [Explanation of symbols]

[0043] 1 shaft 2. Lightweight layer 2A Outer surface 2B Inner surface 3 Cavity 5 Straight Layer 6 bias layer f1 short fiber f2 long fiber

Claims

1. A method for manufacturing a shaft made of fiber reinforced resin, The shaft includes at least a lightweight layer made of fiber reinforced resin, the lightweight layer includes a plurality of cavities extending in the shaft axial direction, The plurality of cavities are spaced apart from one another in the circumferential direction of the shaft, The method for manufacturing the shaft includes: a first step of preparing the lightweight layer in the form of a sheet material, the lightweight layer including an outer surface in the shaft radial direction, an inner surface in the shaft radial direction, and the plurality of cavities disposed therebetween; a second step of winding the sheet material annularly around the shaft; A method for manufacturing a shaft.

2. The method for manufacturing a shaft according to claim 1 , wherein the lightweight layer is continuous around the shaft circumferentially for at least one revolution.

3. 3. The method for manufacturing a shaft according to claim 1, wherein the lightweight layer is a sheet-like body that defines an outer surface in the shaft radial direction and an inner surface in the shaft radial direction and extends annularly along the shaft circumferential direction.

4. The method for manufacturing a shaft according to claim 1 , wherein the lightweight layer is a composite of reinforcing fibers and a resin.

5. The method for manufacturing a shaft according to claim 4 , wherein the reinforcing fibers include short fibers.

6. The method for manufacturing a shaft according to claim 4 or 5, wherein the reinforcing fibers include pipe-shaped fibers surrounding the hollow portion.

7. A method for manufacturing a shaft described in any one of claims 1 to 6, wherein the shaft is a golf club shaft.

8. A method for manufacturing a shaft as described in Claim 7, wherein the shaft has a bias layer on the radially inward side of the lightweight layer, in which reinforcing fibers are oriented at an angle of 45°±15° relative to the axial direction of the shaft.

9. A method for manufacturing a shaft as described in claim 7 or 8, wherein the shaft has a straight layer on the radial outside of the lightweight layer in which reinforcing fibers are oriented at an angle of 0°±5° relative to the axial direction of the shaft.

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