CN107413028B

CN107413028B - Cylindrical laminated structure and sports article using same as rod body

Info

Publication number: CN107413028B
Application number: CN201710073025.8A
Authority: CN
Inventors: 户谷祯志
Original assignee: Globeride Inc
Current assignee: Globeride Inc
Priority date: 2016-02-16
Filing date: 2017-02-10
Publication date: 2020-10-02
Anticipated expiration: 2037-02-10
Also published as: CN107413028A; JP2017143956A; JP6726980B2

Abstract

The invention provides a cylindrical laminated structure which can present an appearance corresponding to a concave-convex pattern repeatedly appearing in a layer more inward than an outermost layer. Specifically, the cylindrical laminated structure of the present invention includes a 1 st layer having a plurality of protrusions and a plurality of recesses that are repeated in at least one of the axial direction and the circumferential direction, and a 2 nd layer provided outside the 1 st layer. The outer surface of the 2 nd layer is composed of a polished surface and a non-polished surface, the polished surface is formed so as to be disposed at a position facing each of the plurality of projections, and the polished surface is disposed at a position facing each of the plurality of projections in the thickness direction of the cylindrical laminated structure.

Description

Cylindrical laminated structure and sports article using same as rod body

Technical Field

The present invention relates to a cylindrical laminated structure. More specifically, the present invention relates to a cylindrical laminated structure used as a shaft for various sports goods.

Background

A conventional shaft for a sports article, particularly a shaft for a golf club (hereinafter referred to as a golf club shaft), includes a cylindrical laminated structure formed by laminating a plurality of resin layers. Each of the plurality of resin layers is formed by heat-curing a prepreg (prepreg sheet) wound around a metal mandrel and fixed with a tape.

The prepreg is obtained by impregnating a reinforcing fiber with a synthetic resin. It is known that the bending rigidity, compressive rigidity, and torsional rigidity of a golf club shaft can be adjusted by the direction of reinforcing fibers included in a prepreg sheet. For example, by using a prepreg having reinforcing fibers extending in the axial direction (longitudinal direction) of the golf club shaft, the bending rigidity of the golf club shaft can be improved. The resin layer formed of such a prepreg is called a 0-degree layer or a straight layer (straight layer) because the reinforcing fibers thereof extend in a direction of substantially 0 degree with respect to the axial direction of the golf club shaft. In order to improve compressive rigidity of the golf club shaft, a prepreg having reinforcing fibers extending in a circumferential direction of the golf club shaft is used. The resin layer formed of such a prepreg is also referred to as a 90-degree layer or a perpendicular layer because the reinforcing fibers thereof extend in a direction of substantially 90 degrees with respect to the axial direction of the golf club shaft. In order to improve torsional rigidity of the golf club shaft, a prepreg having reinforcing fibers extending in an axial direction (longitudinal direction) oblique to the golf club shaft is used. The resin layer formed of such a prepreg is also called a bias layer (bias layer) because the reinforcing fibers thereof extend in a direction oblique to the axial direction of the golf club shaft.

In addition, a prepreg is used in the golf club shaft, which is formed by weaving a fiber bundle formed by bundling reinforcing fibers and impregnating the woven fiber bundle with a synthetic resin. The resin layer formed from such a prepreg is also referred to as a fabric layer. Further, a prepreg in which a plurality of fiber bundles are combined with each other and a synthetic resin is impregnated into the combined fiber bundles may be used. The resin layer formed from such a prepreg is also referred to as a buildup layer. Conventional golf club shafts having such a fabric layer or cloth set layer are disclosed in, for example, japanese patent laid-open nos. 2007 & 000429 (patent document 1), 2009 & 219919 (patent document 2), 2000 & 245854 (patent document 3), and 2012 & 179734 (patent document 4). As described in these known documents, in a conventional golf club shaft having a fabric layer or a set cloth layer, a straight layer for improving bending rigidity is provided on the outer side of the fabric layer or the set cloth layer. For example, in patent document 1, a prepreg 15 as a straight layer is provided outside a prepreg 10 as a fabric layer. Since the fabric layer or the fabric set layer is thick at the position where the fiber bundle is arranged and the other portions are thin, irregularities are formed on the surface of the fabric layer or the fabric set layer. In addition, irregularities corresponding to the irregularities of the fabric layer also appear on the surface of the linear layer disposed outside the fabric layer or set of fabric layers.

Since traces of the bandage remain on the surface of the linear layer provided outside the fabric layer during the heat curing treatment, the outer surface of the linear layer is subjected to the polishing treatment after the heat curing treatment. By this grinding process, the outer surface of the linear layer is flattened and the mark of the bandage is removed. In addition, the bending rigidity of the golf club shaft is adjusted by cutting off a part of the reinforcing fiber of the straight layer by the grinding process.

Patent document 1: japanese patent laid-open No. 2007 and 000429

Patent document 2: japanese patent laid-open publication No. 2009-219919

Patent document 3: japanese patent laid-open No. 2000-2458880

Patent document 4: japanese laid-open patent publication No. 2012-179734

Disclosure of Invention

As described above, in the conventional golf club shaft having a fabric layer or a cloth set layer, a mark of a bandage is removed by flattening the surface of a straight layer using a grinding process, thereby achieving an improvement in the appearance of the golf club shaft. However, by this polishing treatment, the irregularities occurring on the outer surface of the linear layer due to the fabric layer or the cloth-assembled layer are also flattened.

In the method for manufacturing the fabric layer or the cloth set layer, the unevenness caused by the fabric layer or the cloth set layer forms a geometric pattern having a repeating pattern in at least one of the axial direction and the circumferential direction. One object of the present invention is to provide a cylindrical laminated structure represented by a golf club shaft, which can exhibit an appearance corresponding to repeated irregularities in a layer located on the inner side of the outermost layer. Other objects of the present invention will become apparent by reference to the specification as a whole.

The cylindrical laminated structure according to the present invention includes: a resin layer composed of a prepreg formed by impregnating a plurality of reinforcing fibers with a synthetic resin; a concave-convex layer formed on the resin layer; and a resin layer formed on the uneven layer, the uneven layer having a plurality of fiber bundle groups extending at mutually different angles and having a plurality of protrusions and a plurality of recesses which are repeated in at least one of an axial direction and a circumferential direction, an outer surface of the resin layer formed on the uneven layer being composed of a polished surface and a non-polished surface, the polished surface being formed so as to be disposed at a position facing the protrusions of each uneven layer, and a geometric pattern having a repeating pattern being formed on at least one of the axial direction and the circumferential direction of the cylindrical laminated structure.

According to the present invention, the outer surface of the 2 nd layer has a polished surface at a position corresponding to the plurality of projections of each of the 1 st layers, and a non-polished surface at a position other than the positions. Thus, the abrasive surface appearing on the outer surface of the 2 nd layer has a repeating pattern corresponding to the arrangement of a plurality of projections which are repeated in at least one of the axial direction and the circumferential direction in the 1 st layer. Thus, a cylindrical laminated structure having an appearance corresponding to the uneven pattern repeatedly appearing in the 1 st layer can be obtained.

In the present invention, the layer 1 is a fabric layer formed by weaving a plurality of fiber bundles. In the present invention, the 1 st layer is a cloth assembly layer formed by bonding a plurality of fiber bundles.

According to the present invention, a cylindrical laminated structure having an appearance corresponding to the irregularities repeatedly appearing in the fabric layer or the set fabric layer can be obtained.

In the present invention, the 2 nd layer is formed such that the non-polished surface is more recessed than the polished surface.

In the cylindrical laminated structure according to the present invention, the portion corresponding to the polished surface and the portion corresponding to the non-polished surface can be visually recognized more clearly. Thus, a cylindrical laminated structure exhibiting an appearance in which the repeated uneven patterns can be more clearly recognized can be obtained.

The cylindrical laminated structure of the present invention further includes a 3 rd layer which is provided outside the 2 nd layer and is made of a material different from that of the 2 nd layer. The 3 rd layer is disposed on the non-abrasive side but not on the abrasive side.

In the cylindrical laminated structure according to the present invention, the 3 rd layer is provided only on the portion corresponding to the non-polished surface in the surface, and therefore, the portion corresponding to the polished surface and the portion corresponding to the non-polished surface can be visually recognized more clearly.

The cylindrical laminated structure of the present invention further includes a transparent 4 th layer provided outside the 2 nd layer and the 3 rd layer. In the present specification, in the case where the 4 th layer is referred to as being transparent, the 4 th layer does not need to be completely transparent, and may be transparent to such an extent that the outer surface of the 2 nd layer can be seen from the outer surface side of the 4 th layer. More specifically, the degree of transparency may be sufficient to allow the polished surface and the non-polished surface on the surface of the 2 nd layer to be recognized when the 2 nd layer is observed from the outer surface side of the 4 th layer.

According to the present invention, even in the case where the 4 th layer is provided outside the 2 nd layer, a cylindrical laminated structure exhibiting an appearance corresponding to the unevenness of the 1 st layer can be obtained.

According to the present invention, a cylindrical laminated structure that can exhibit an appearance corresponding to a concave-convex pattern that repeatedly appears in a layer located further inside than the outermost layer can be obtained.

Drawings

Fig. 1 is a schematic view of a golf club provided with a golf club shaft according to the cylindrical laminated structure of the present invention.

Fig. 2 is a schematic view illustrating a method of manufacturing the golf club shaft shown in fig. 1.

Fig. 3 is a cross-sectional view schematically showing a cross section of a laminated structure (a laminated structure before polishing treatment described later) composed of resin layers laminated on a mandrel 20, cut on a plane passing through the central axis of the mandrel 20.

Fig. 4 is a plan view of a relief layer 30 that may be used in the golf club shaft of the present invention.

Fig. 5 is an enlarged plan view of a part of the concave-convex layer 30 shown in fig. 4.

Fig. 6 is a schematic diagram showing a cross section of a golf club shaft according to an embodiment of the present invention.

Fig. 7 is a schematic view showing a concave-convex pattern appearing in the concave-convex layer 30.

Fig. 8 is a schematic diagram showing a cross section of a golf club shaft according to an embodiment of the present invention.

Description of the symbols

10-a golf club; 12. 112-a golf club shaft; 21-1 st resin layer; 22-2 nd resin layer; 23-3 rd resin layer; 24-4 th resin layer; 25-5 th resin layer; 30-a relief layer; 40-coating layer.

Detailed Description

Hereinafter, various embodiments of the present invention will be described with reference to the drawings as appropriate. In the drawings, the same reference numerals are given to the common components. For convenience of explanation, the drawings are not necessarily limited to the description on a correct scale, and it is desirable to note this.

Hereinafter, a description will be given of a case where the present invention is applied to a golf club shaft as a representative example of the cylindrical laminated structure according to the present invention, but the present invention is applicable to any laminated structure, and it is desirable to note this. For example, the present invention is applicable to all sports goods including a golf club shaft, a tennis racket shaft, a badminton racket shaft, and a fishing rod shaft.

Fig. 1 is a schematic diagram showing a configuration of a golf club including a golf club shaft according to an embodiment of the present invention. As shown in fig. 1, the golf club 10 includes a golf club shaft (hereinafter, may be simply referred to as "shaft") 12, a head 14 attached to one end 12a of the shaft 12 via a hosel 14a, and a grip 16 attached to the other end 12b of the shaft 12 so as to cover the other end 12 b.

Fig. 2 is a schematic view showing a method of manufacturing the shaft 12 shown in fig. 1. As shown in fig. 2, the shaft 12 is formed by sequentially winding (superposing) a rod-shaped mandrel (mandrel) 20 having a central axis C around a plurality of resin layers shown in fig. 2 from above to below. The central axis C of the mandrel 20 coincides with the central axis of the finally formed shaft 12. One end 20a and the other end 20b of the plug 20 correspond to one end 12a and the other end 12b of the shaft 12 manufactured using the plug 20, respectively.

Fig. 3 is a cross-sectional view schematically showing a cross section of a laminated structure (a laminated structure before polishing treatment described later) composed of resin layers laminated on a mandrel 20, cut on a plane passing through the central axis of the mandrel 20. Hereinafter, a method of manufacturing the shaft 12 and a laminated structure will be described with reference to fig. 2 and 3.

The 1 st resin layer 21 is a layer that is first wound around the mandrel 20. In one embodiment, the 1 st resin layer 21 is a sheet formed in a quadrangle having a width expanding from one end 21a toward the other end 21b and formed by impregnating a synthetic resin into a prepreg formed by a plurality of reinforcing fibers arranged to extend at a predetermined angle (for example, 45 degrees) with respect to the central axis C.

The 2 nd resin layer 22 is a layer wound around the mandrel 20 following the 1 st resin layer 21. In one embodiment, the 2 nd resin layer 22 is a sheet formed in a quadrangle having a width expanding from one end 22a toward the other end 22b and a prepreg formed by impregnating a synthetic resin in a plurality of reinforcing fibers arranged to extend at a predetermined angle (for example, -45 degrees) with respect to the central axis C.

The 1 st resin layer 21 and the 2 nd resin layer 22 are wound around a region extending from the vicinity of the one end 20a to the vicinity of the other end 20b of the mandrel 20, thereby contributing to an increase in torsional rigidity of the entire finally formed shaft 12.

The 3 rd resin layer 23 is a layer wound around the mandrel 20 following the 2 nd resin layer 22. The 3 rd resin layer 23 is a sheet formed in a quadrangle having a width expanding from one end 23a toward the other end 23b and made of a prepreg formed by impregnating resin into a plurality of reinforcing fibers arranged to extend parallel to the central axis C. The 3 rd resin layer 23 is wound around a region extending from the vicinity of the one end 20a of the mandrel 20 to the vicinity of the other end 20b, thereby contributing to increase in bending rigidity of the entire finally formed shaft 12.

The uneven layer 30 is a layer wound around the mandrel 20 following the 3 rd resin layer 23. The relief layer 30 is also constituted by a sheet formed in a quadrilateral shape having a width expanding from one end 30a toward the other end 30 b. In one embodiment of the present invention, the uneven layer 30 is formed to have a plurality of convex portions and a plurality of concave portions that are repeated in at least one of the axial direction and the circumferential direction. In one embodiment of the present invention, the uneven layer 30 may be a woven fabric layer in which each fiber bundle is woven. The uneven layer 30 may be a cloth assembly layer in which combined fiber bundles are bonded to each other.

The relief layer 30 will be further described with reference to fig. 4 and 5. Fig. 4 is a top view of the relief layer 30. Fig. 5 is an enlarged plan view of a part of the concave-convex layer 30 shown in fig. 4. As shown in fig. 4 and 5, the uneven layer 30 includes 5 fiber bundle groups extending at different angles with respect to the central axis a of the mandrel 20 (the extending direction of the central axis a is the same as the "axial direction" shown in fig. 4). Specifically, the uneven layer 30 includes a 1 st fiber bundle group X extending perpendicularly to the central axis a, a 2 nd fiber bundle group Y and a 3 rd fiber bundle group Y 'extending at angles of + α degrees and- α degrees, respectively, with respect to the central axis a, and a 4 th fiber bundle group Z and a 5 th fiber bundle group Z' extending at angles of + β degrees and- β degrees, respectively, with respect to the central axis a. Fig. 4 and 5 show, as an example, a configuration in which α and β are 60 and 30, respectively. The angles of the fiber bundles y, y 'with respect to the central axis a are not limited to +60 degrees and-60 degrees, respectively, and the angles of the fiber bundles z, z' with respect to the central axis a are not limited to +30 degrees and-30 degrees, respectively.

In the uneven layer 30, the 1 st fiber bundle group X is composed of a plurality of fiber bundles X arranged at intervals P1 (for example, 18mm) from each other. The 2 nd fiber bundle group Y (the 3 rd fiber bundle group Y ') is composed of a plurality of fiber bundles Y (a plurality of fiber bundles Y') arranged at intervals P2 (for example, 8mm) from each other. Similarly, the 4 th fiber bundle group Z (5 th fiber bundle group Z ') is composed of a plurality of fiber bundles Z (a plurality of fiber bundles Z') arranged at intervals P3 (e.g., 9mm) from each other. Each fiber bundle (x, y ', z') is formed by bundling hundreds to tens of thousands of fibers and then impregnating synthetic resin. The uneven layer 30 may be a woven layer formed by weaving the fiber bundles x, y ', z, and z'. The uneven layer 30 may be a cloth assembly layer in which the fiber bundles x, y ', z, and z' are bonded by an adhesive.

The concave-convex pattern of the concave-convex layer 30 will be described with reference to fig. 7. Fig. 7 is a schematic view of the concave-convex layer 30, and is an additional view for illustrating the concave-convex pattern in fig. 4. As shown in fig. 7, thin portions where any fiber bundles x, y ', z, and z' do not exist are repeatedly present in the uneven layer 30 at regular intervals in the axial direction and the circumferential direction. In the example shown in fig. 7, the existing region R1 is repeated in the circumferential direction and the axial direction. In the region R1, since any fiber bundle x, y ', z' does not exist, the thickness is thinner than other portions of the uneven layer 30. In addition, in the uneven layer 30, thick portions that become thicker than other portions due to overlapping of the fiber bundles x, y ', z, and z' repeatedly appear at regular intervals in the axial direction and the circumferential direction. In the example shown in fig. 7, the existing region R2 is repeated in the circumferential direction and the axial direction. In the region R2, the fiber bundles x, y ', z' overlap and thus become relatively thicker than other parts of the relief layer 30. In this way, in the uneven layer 30, the relatively thin concave portions (for example, the region R1) and the relatively thick convex portions (for example, the region R2) are repeatedly formed at regular intervals in the axial direction and the circumferential direction. Since the region R1 is thin and recessed more than other regions of the concave-convex layer 30 as described above, the region R1 is also referred to as a concave portion R1 in this specification. Since the region R2 is thick as described above and protrudes from the other regions of the uneven layer 30, the region R2 is also referred to as an elevated portion R2 in the present specification. In this way, the uneven layer 30 has a plurality of convex portions R2 and a plurality of concave portions R1 that are repeated in the axial direction and the circumferential direction.

The recesses repeatedly appearing on the relief layer 30 are not limited to 1 pattern, and there may be more than 2 patterns of recesses on the relief layer 30. For example, since the region indicated by reference symbol R3 in fig. 7 does not have a fiber bundle inside it, the region can be thinned more easily than other regions. Thus, the region R3 also forms a recessed portion that is recessed more than other regions of the concave-convex layer 30. The recess R3 also repeats in the axial and circumferential directions.

The convex portions repeatedly appearing on the uneven layer 30 are not limited to 1 pattern, and convex portions of 2 or more patterns may be present on the uneven layer 30. For example, since 3 fiber bundles are overlapped in the region indicated by reference symbol R4 in fig. 7, the fiber bundles are more likely to be thickened than other regions. Thus, the region R4 also forms a convex portion that protrudes more than other regions of the concave-convex layer 30. The convex portion R4 also repeats in the axial direction and the circumferential direction.

The region R1 and the region R3 are only examples of concave portions in the concave-convex layer 30, and the region R2 and the region R4 are only examples of convex portions in the concave-convex layer 30. The method of defining the convex and concave portions in the uneven layer 30 is not limited to the above-described embodiment. For example, a reference surface extending in the circumferential direction at a predetermined position in the thickness direction of the uneven layer 30 may be defined, and a portion located above the reference surface (outside the golf club shaft 12) may be defined as a convex portion, and a portion located below the reference surface (inside the golf club shaft 12) may be defined as a concave portion.

In order to form the uneven structure of the uneven layer 30, a commercially available carbon ribbon may be used instead of the above-described fiber bundle (x, y ', z'). For example, the uneven layer 30 formed of the carbon tape may be formed by winding the carbon tape on the surface of the 3 rd resin layer 23 so that the convex portions and the concave portions are repeatedly formed in at least one of the axial direction and the circumferential direction. The gap between the carbon ribbons may be filled with a synthetic resin in the uneven layer 30.

The fabric layer applicable to the present invention is not limited to that shown in fig. 4 and 5. The uneven layer applicable to the present invention may be a layer having a plurality of convex portions and a plurality of concave portions which are repeated in at least one of the axial direction and the circumferential direction. For example, the uneven layer including only the fiber bundle x may be used by omitting the fiber bundles y, y ', z, and z' from the uneven layer 30 shown in fig. 4.

The 4 th resin layer 24 is a layer wound around the mandrel 20 after the uneven layer 30. The 4 th resin layer 24 is also constituted by a sheet formed in a quadrangle having a width expanding from one end 24a toward the other end 24 b. Like the 3 rd resin layer 23, the 4 th resin layer 24 is formed of a prepreg formed by impregnating a resin into a plurality of reinforcing fibers arranged to extend parallel to the central axis C. The winding of the 4 th resin layer 24 around the region extending from the vicinity of the one end 20a to the vicinity of the other end 20b of the mandrel 20 also contributes to an increase in bending rigidity of the entire finally formed shaft 12.

As described above, the uneven pattern due to each fiber bundle included in the uneven layer 30 is formed on the surface of the uneven layer 30. Therefore, an uneven pattern corresponding to the uneven pattern of the uneven layer 30 is also present on the outer surface of the 4 th resin layer 24. Specifically, the 4 th resin layer 24 formed outside the uneven layer 30 includes a convex portion 24a at a position corresponding to a convex portion (for example, the convex portion R2, the convex portion R4) of the uneven layer 30 in the thickness direction of the shaft 12, and a concave portion 24b recessed more than the convex portion 24 a. The recessed portion 24b is disposed at a position where each fiber bundle of the uneven layer 30 is not present in the thickness direction of the shaft 12 or in a recessed portion (for example, recessed portion R1 or recessed portion R3).

The 5 th resin layer 25 is a layer wound around the mandrel 20 after the 4 th resin layer 24. The 5 th resin layer 25 is also constituted by a sheet formed in a quadrangular shape having a width expanding from one end 25a toward the other end 25 b. The 5 th resin layer 25 is formed of a prepreg formed by impregnating a plurality of reinforcing fibers arranged to extend parallel to the central axis C with a transparent resin. The winding of the 5 th resin layer 25 around the region extending from the vicinity of the one end 20a to the vicinity of the other end 20b of the mandrel 20 also contributes to an increase in bending rigidity of the entire finally formed shaft 12.

The reinforcing fibers used for the resin layers and the uneven layer 30 include various reinforcing fibers including carbon fibers, metal fibers, glass fibers, aramid fibers, and the like. As the resin for impregnating the reinforcing fibers, any of thermosetting resins and thermoplastic resins can be used. The thermosetting resin that can be used includes, for example, epoxy, bismaleimide, polyimide, phenol, and the like. Examples of the usable thermoplastic resin include polyether ether ketone (PEEK), polyether sulfone (PES), polyether imide (PEI), polyphenylene sulfide (PPS), Polyamide (PA), polypropylene (PP), and the like.

The description of the method of manufacturing the golf club shaft 12 is continued with reference to fig. 2 again. After the 1 st resin layer 21, the 2 nd resin layer 22, the 3 rd resin layer 23, the uneven layer 30, the 4 th resin layer 24, and the 5 th resin layer 25 are sequentially wound around the mandrel 20, a molding tape is spirally wound around the outer peripheral surface of the 5 th resin layer 25 on the outermost side. The mandrel bar 20 with the molding tape wound around the surface thereof is stored in a pot and fired.

Thereafter, the mandrel 20 is pulled out from the laminated structure formed on the mandrel 20. Thus, the laminated structure 52 including the 1 st resin layer 21, the 2 nd resin layer 22, the 3 rd resin layer 23, the uneven layer 30, the 4 th resin layer 24, and the 5 th resin layer 25 all of which have been heat-cured can be obtained. The laminated structure 52 is subjected to polishing treatment described later.

The laminated structure 52 is only one example of the laminated structure applicable to the present invention, and it is desirable to note this. For example, a laminated structure in which a part of the 1 st resin layer 21, the 2 nd resin layer 22, the 3 rd resin layer 23, the uneven layer 30, the 4 th resin layer 24, and the 5 th resin layer 25 is omitted may be subjected to polishing in the next step. Further, a laminated structure obtained by replacing a part of the 1 st resin layer 21, the 2 nd resin layer 22, the 3 rd resin layer 23, the uneven layer 30, the 4 th resin layer 24, and the 5 th resin layer 25 with another resin layer may be subjected to polishing treatment in the next step.

A laminated structure obtained by providing resin layers other than the 1 st resin layer 21, the 2 nd resin layer 22, the 3 rd resin layer 23, the uneven layer 30, the 4 th resin layer 24, and the 5 th resin layer 25 may be subjected to polishing treatment in the next step. For example, a 90 degree layer may also be provided between the relief layer 30 and the 4 th resin layer 24. The 90-degree layer is formed of a prepreg formed by impregnating resin into a plurality of reinforcing fibers arranged to extend perpendicularly to the central axis C. By wrapping the 90-degree layer around the region extending from near the one end 20a to near the other end 20b of the mandrel 20, the compressive rigidity of the finally formed shaft 12 as a whole can be increased.

The outer surface of the laminated structure 52 is polished. In one embodiment, the laminated structure 52 is polished to a processing plane P1 shown in fig. 3. As shown in fig. 3, the processing surface P1 is disposed at a position where at least a part of the convex portion 24a of the 4 th resin layer 24 is polished but the concave portion 24b of the 4 th resin layer 24 is not polished at all. The polishing process of the laminated structure 52 can be performed by any mechanical polishing such as a grinder, a sandpaper, or a polishing.

By this grinding process, a golf club shaft 12 having a cross section shown in fig. 6 can be obtained. As shown in fig. 6, the outer surface of the 4 th resin layer 24 after polishing includes a polished surface S1 obtained by polishing the convex portions 24a and a non-polished surface S2. As described above, at least a part of the concave portion 24b remains without being polished in the polishing process. The non-polished surface S2 corresponds to a surface that has not been polished by the polishing process, among the outer surfaces of the recessed portion 24 b. As described above, the polished surface S1 is formed at the position corresponding to the convex portion of the uneven layer 30 on the outer surface of the golf club shaft 12 according to the embodiment of the present invention, and the non-polished surface S2 is formed at the other position (for example, a concave portion). Thus, the golf club shaft 12 takes on an appearance having a repeating pattern corresponding to the repeating pattern of the convex and concave portions repeatedly appearing on the concave and convex layer 30.

As described above, in the conventional golf club shaft, the surface of the laminated structure after thermosetting is also subjected to polishing (see patent documents 1 to 4). However, since the conventional polishing is performed for the purpose of flattening the surface of the laminated structure, the polishing process is performed to a processing surface (for example, an assumed processing surface P2 shown in fig. 6) on the inner side of the concave portion 24 b. Therefore, in the conventional polishing process, the irregularities on the outer surface of the 4 th resin layer 24 due to the irregularities of the irregular layer 30 are flattened. Therefore, the unevenness of the inner fabric layer or the like cannot be expressed on the outer surface of the conventional golf club shaft.

In one embodiment, the polishing process is performed so that the non-polished surface S2 is recessed by about 0.02mm to 0.03mm from the polished surface S1. In this way, since the non-polished surface S2 is more recessed than the polished surface S1, the non-polished surface S2 becomes easier to look darker. Thus, it is convenient to make the ground surface S1 and the non-ground surface S2 have contrast, so that the appearance corresponding to the unevenness of the uneven layer 30 can more clearly appear on the outer surface of the golf club shaft 12.

On the recess 24b, an unpolished portion of the 5 th resin layer 25 disposed outside the 4 th resin layer 24 remains. For example, as shown in fig. 6, the 5 th resin layer 25 having a thickness T (about 0.02mm to 0.03 mm) corresponding to the depth of the recess 24b remains on the recess 24 b. By forming the 5 th resin layer 25 from a different material from the 4 th resin layer, it is convenient to impart contrast to the ground surface S1 and the non-ground surface S2, and thus an appearance corresponding to the unevenness of the uneven layer 30 can more clearly appear on the outer surface of the golf club shaft 12. In one embodiment, in order to obtain such a difference in contrast, the 5 th resin layer 25 is formed to contain a reinforcing fiber different from the reinforcing fiber contained in the 4 th resin layer 24. For example, carbon fibers may be used as the reinforcing fibers of the 4 th resin layer 24, and glass fibers may be used as the reinforcing fibers of the 5 th resin layer 25. In another embodiment, in order to obtain the above-described difference in contrast, a synthetic resin of a different kind from the synthetic resin of the reinforcing fibers impregnated in the 4 th resin layer 24 is impregnated into the reinforcing fibers of the 5 th resin layer 25. The 5 th resin layer 25 may be different from the 4 th resin layer 24 in both the reinforcing fibers and the synthetic resin impregnated in the reinforcing fibers.

A golf club shaft 112 according to another embodiment of the present invention will be described with reference to fig. 8. Fig. 8 is a schematic view showing a cross section of the golf club shaft 112. The golf club shaft 112 is different from the golf club shaft 12 in that a transparent paint layer 40 is coated on a surface of a ground laminated structure. The paint layer 40 does not need to be completely transparent, and may be transparent to the extent that the polished surface S1 and the non-polished surface S2 on the outer surface of the 4 th resin layer 24 can be recognized when viewed from the outer surface side of the paint layer 40. According to the golf club shaft 112 of fig. 8, even if the paint layer 40 is provided outside the ground surface S1 and the non-ground surface S2, an appearance corresponding to the unevenness of the uneven layer 30 can be presented.

The dimensions, materials, and arrangements of the respective constituent elements described in the present specification are not limited to those explicitly described in the embodiments, and the respective constituent elements may be modified so as to have arbitrary dimensions, materials, and arrangements within the scope of the present invention. In the embodiments described above, components not explicitly described in the present specification may be added, and some of the components described in the embodiments may be omitted.

Claims

1. A cylindrical laminated structure, comprising:

a resin layer composed of a prepreg formed by impregnating a plurality of reinforcing fibers with a synthetic resin;

a concave-convex layer formed on the resin layer; and

a resin layer formed on the concavo-convex layer,

the uneven layer has a plurality of fiber bundle groups extending at mutually different angles and having a plurality of protrusions and a plurality of recesses which are repeated in at least one of an axial direction and a circumferential direction,

the outer surface of the resin layer formed on the uneven layer is composed of a polished surface and a non-polished surface, the polished surface is formed so as to be disposed at a position facing the convex portion of each uneven layer,

a geometric pattern having a repeating pattern is formed on at least one of the axial direction and the circumferential direction of the cylindrical laminated structure.

2. The cylindrical build-up structure according to claim 1, wherein the resin layer formed on the uneven layer is formed such that the non-polished surface is recessed more than the polished surface.

3. The cylindrical build-up structure according to claim 1 or claim 2, further comprising a 3 rd layer which is provided outside the resin layer formed on the uneven layer and is made of a different material from the resin layer formed on the uneven layer, wherein the 3 rd layer is provided on the non-polished surface but not on the polished surface.

4. The cylindrical build-up structure according to claim 3, further comprising a transparent 4 th layer provided outside the resin layer formed on the uneven layer and the 3 rd layer.

5. The cylindrical laminated structure according to claim 1 or claim 2, wherein the cylindrical laminated structure is a golf club shaft, a badminton racket shaft, a tennis racket shaft, a ski pole shaft, or a fishing rod shaft.

6. The cylindrical laminated structure according to claim 3, wherein the cylindrical laminated structure is a shaft for a golf club, a shaft for a badminton racket, a shaft for a tennis racket, a shaft for a ski pole, or a shaft for a fishing rod.

7. The cylindrical laminated structure according to claim 4, wherein the cylindrical laminated structure is a shaft for a golf club, a shaft for a badminton racket, a shaft for a tennis racket, a shaft for a ski pole, or a shaft for a fishing rod.

8. A sporting good comprising the cylindrical laminated structure according to any one of claims 1 to 4 as a shaft.

9. The sporting good of claim 8, wherein the sporting good is a golf club.

10. The sporting good of claim 8, wherein the sporting good is a fishing rod.