JP2020146268A - Golf club and method for manufacturing shaft of golf club - Google Patents

Abstract

To provide a golf club fitted with a shaft whose appearance is improved without causing variations in hardness.SOLUTION: A golf club according to the present invention comprises a shaft made of fiber reinforced resin. The shaft comprises: a main body layer 10A arranged on the inside in the radial direction, and formed of a high-temperature curing material; and an appearance exposure layer 10C arranged on the outside in the radial direction, and formed of a low-temperature curing material.SELECTED DRAWING: Figure 2

Description

The present invention relates to a golf club, and more particularly to a golf club having a characteristic shaft and a method for manufacturing the shaft.

Conventionally, as a shaft of a golf club, a shaft made of a fiber reinforced resin (hereinafter referred to as FRP) is known. As is known, in the FRP shaft, a plurality of prepreg sheets in which reinforcing fibers are impregnated with synthetic resin are wound around a core metal, and the shaft is fixed with a tightening tape, which is then thermoset and decentered. (See, for example, Patent Document 1).
With the shaft formed in this way, it is difficult to accurately control the variation in the material itself, the winding state of the prepreg sheet with respect to the core metal, the resin flow during molding, etc., and the hardness after molding varies. The current situation is that there is. For this reason, in an actual manufacturing site, the surface of the molded shaft is polished in order to keep the variation in hardness at the time of molding within a certain range.

JP-A-2018-94085

However, when the surface is polished in order to correct the variation in the hardness of the shaft, there arises a problem that the reinforcing fibers are cut. In the shaft of a golf club, there are cases where it is desired to visually recognize the forming material itself as an appearance (the orientation state of the reinforcing fibers in the outermost layer is visually recognized; also referred to as appearance), but the appearance deteriorates when the reinforcing fibers are cut. Therefore, the amount of polishing of the outermost layer is set to be small (about fine surface polishing). Therefore, if priority is given to improving the appearance (the amount of polishing of the outermost layer is set to be small), the variation in the hardness of the shaft must be tolerated, and the shaft performance must be sacrificed.

On the other hand, by winding a prepreg sheet made of glass fiber as the outermost layer, it is possible to expose the base layer of the translucent glass material.
However, since the glass material has a small influence on the frequency, it is necessary to wind a large number of prepreg sheets made of glass fibers in order to keep the frequency within a certain range. Since the glass material is translucent (not transparent), the visibility of the base layer (external material) is reduced, and the appearance and weight of the external material vary greatly due to the difference in the amount of polishing. turn into.

The present invention has been made by paying attention to the above-mentioned problems, and provides a golf club equipped with a shaft having an improved appearance without causing a variation in hardness, and a method for manufacturing such a shaft. The purpose is to do.

In order to achieve the above object, the present invention relates to a golf club provided with a shaft made of a fiber reinforced resin, wherein the shaft is arranged inside in the radial direction and is formed of a high temperature curing material, and a main body layer thereof and a diameter thereof. It is characterized by having an externally exposed layer disposed on the outer side in the direction and formed of a low-temperature curing material.

In the above-mentioned golf club shaft structure, the inner layer side has a main body layer made of a resin material that cures at a high temperature, and the outer layer side has an appearance exposed layer made of a resin material that cures at a low temperature (appearance material). After the main body layer on the inner layer side is heat-treated, the surface is polished to adjust the hardness variation in advance, and then the appearance material can be additionally molded. That is, it is possible to improve the appearance while maintaining the performance of the shaft at a certain level.

In addition, the present invention may have a configuration in which the appearance is improved by disposing the appearance material on the surface of a normal steel shaft. In such a configuration, an externally exposed layer formed of a prepreg sheet made of fiber reinforced resin may be wound around at least a part of a region of the steel shaft configured as a tubular body. In this case, when the wound prepreg sheet is thermoset, the surface of the portion where the prepreg sheet is wound is covered so that the adhesion with the steel shaft surface is improved and peeling does not occur (the appearance is not deteriorated). It is preferable to roughen the surface.

Further, in order to achieve the above-mentioned object, the present invention provides a method for manufacturing a shaft of a golf club, in which a prepreg sheet made of a high-temperature curing material is wound around a core metal and heated to form a tubular main body layer. A first molding step of forming a surface, a polishing step of polishing the surface of the main body layer formed by the first molding step, and a prepreg sheet made of a low-temperature curing material are wound around the main body layer whose surface has been polished. It is characterized by having a second molding step of forming an externally exposed layer by heating.

In the above-mentioned manufacturing method, a tubular main body layer is formed in the first molding step, and the surface is polished in the subsequent polishing step to make the hardness variation of the shaft (tubular main body layer) constant. Can be contained in the range of. After that, a prepreg sheet made of a low-temperature curing material that cures at a lower temperature than the resin of the main body layer used in the first molding step is wound and heated to heat the high-temperature curing material disposed on the inner layer side. Since a prepreg sheet made of a low-temperature curing material can be used as an appearance material without affecting the shaft, it is possible to manufacture a shaft that can improve the appearance while maintaining the performance of the shaft at a certain level. ..

According to the present invention, a golf club equipped with a shaft having an improved appearance and a manufacturing method capable of easily manufacturing such a shaft can be obtained without causing a variation in hardness.

A front view showing an example of a golf club. FIG. 5 is a pattern diagram showing an arrangement example of a prepreg sheet which is a constituent material of the shaft shown in FIG. (A) is a cross-sectional view of the shaft of the portion where the externally exposed layer is provided, and (b) is a vertical cross-sectional view along the axial direction at that position. A flowchart illustrating an example of a shaft manufacturing process.

Hereinafter, embodiments of the golf club according to the present invention will be described with reference to the drawings.
The golf club 1 shown in FIG. 1 exemplifies a wood-type golf club, in which a head 30 is attached to the tip end side of the shaft 10 and a grip formed of rubber or the like is attached to the base end side of the shaft 10. 40 is attached.

The shaft 10 is formed by a sheet winding method, and is made of FRP formed by winding a prepreg sheet in which reinforcing fibers are impregnated with a synthetic resin around a core metal, and then thermosetting and decentering the prepreg sheet. is there. The prepreg sheet wound around the core metal includes a prepreg sheet wound over the entire length of the shaft 10 (hereinafter, also referred to as a main body sheet, which constitutes a main body layer as a laminated structure), a head mounting area, and a grip. A prepreg sheet (hereinafter, also referred to as a reinforcing sheet, which constitutes a reinforcing layer as a laminated structure) that is wound to partially improve the strength of the mounting area, etc., and a main body layer that is wound outward in the radial direction. A prepreg sheet (hereinafter, also referred to as an appearance sheet, which constitutes an appearance exposed layer as a laminated structure), which is formed as an appearance material for exposing the appearance, is provided.

A plurality of main body sheets constituting the main body layer and a plurality of reinforcing sheets forming the reinforcing layer may exist. Further, the appearance sheet constituting the appearance exposed layer may be wound over the entire length of the shaft 10 or may be wound within a certain length range in the axial direction. It may be configured so that it is not wound all around.

In the present invention, a type in which the base material (matrix resin) of the prepreg sheet constituting the main body sheet (reinforcing sheet) and the base material of the prepreg sheet constituting the appearance sheet are different is used, and the main body is used. As the sheet (reinforcing sheet), a type that cures at a high temperature (hereinafter, also referred to as a high-temperature curing material) is used, and the appearance sheet is a type that cures at a lower temperature (hereinafter, also referred to as a low-temperature curing material). ) Is used. In producing the shaft 10, after the heat treatment step of forming the main body layer to be the inner layer side, surface polishing is performed to correct the variation in hardness, and the surface-polished main body layer is compared with the outer layer side. This is because the heat treatment step of forming the appearance exposed layer is performed (double molding is performed). That is, the main body layer in the processed state is not affected by heat (for example, the influence of softening, the viscosity is lowered, and the adhesion is lowered) when the appearance exposed layer is formed. As the appearance sheet, a type that cures at a lower temperature than the main body sheet is used.

Specifically, as the prepreg sheet constituting the main body sheet (reinforcing sheet), a thermosetting resin (for example, epoxy resin) that cures at around 120 ° to 130 ° is used as the base material, and constitutes the appearance sheet. As the prepreg sheet, a thermosetting resin (for example, epoxy resin) that cures at a temperature lower than the above-mentioned curing temperature, for example, 100 ° or less, preferably around 70 ° to 80 °, is used as the base material. The reinforcing fibers constituting each prepreg sheet are not particularly limited, and organic fibers such as para-aromatic polyamide and high-strength polyethylene, carbon fibers, glass fibers, boron fibers, silicon carbide fibers, etc. Inorganic fibers such as alumina fibers and further metal fibers can be used, and two or more of these fibers may be used in combination.

Further, the reinforcing fibers constituting the above-mentioned prepreg sheet may be knitted or may be aligned in one direction (axial length direction, circumferential direction, inclined direction). In this case, since the appearance sheet serves as an appearance material, it is preferable to use a structure that improves the appearance, for example, a plain weave, a braided cloth, or a sheet having a metal wire interposed therebetween. The resin impregnation amount (RC) of each prepreg sheet is not particularly limited, but the appearance sheet is provided so that the adhesion strength is ensured between the appearance sheet and the main body layer molded by the main body sheet. It is preferable that the resin impregnation amount is higher to some extent than the main body sheet. However, if the amount of resin impregnated is too high, the work becomes sticky and difficult to work (in the case of 45%, the work is difficult to obtain), so it is preferable to use about 30 to 40%. For example, it is possible to use a main body sheet having a resin impregnation amount of about 15 to 35% and an appearance sheet having a resin impregnation amount of about 20 to 45%.

Hereinafter, with reference to FIG. 2, a configuration example of a shaft having the above characteristics (configuration of a main body sheet, a reinforcing sheet, an appearance sheet wound around a core metal 50, and an arrangement example thereof) will be described.

In FIG. 2, the main body sheet constituting the main body layer 10A is wound over the entire length L of the shaft, and the main body sheet 11 in which the reinforcing fibers are aligned in the circumferential direction and the reinforcing fibers in the axial length direction are arranged from the inner layer side. Main body sheet 12 in which the first oblique sheet aligned in the + 45 ° direction and the second oblique sheet aligned in the -45 ° direction with respect to the axial length direction are superposed with respect to the main body sheet 12, reinforced. The main body sheets 13, 14 and 15 in which the fibers are aligned in the axial length direction are provided. In this case, the number of turns of each main body sheet is not limited, and the arrangement order, pattern shape, and direction of the reinforcing fibers are not limited.
In the figure, the region indicated by L1 is a portion where the head is inserted, and the region indicated by L2 is a portion where the grip is mounted.

A reinforcing sheet 17 is wound around the tip side on which the head is mounted on the main body sheet constituting the main body layer 10A to form the reinforcing layer 10B. The reinforcing sheet 17 is configured by aligning the reinforcing fibers in the axial length direction, but the direction of the reinforcing fibers is not limited. Further, if necessary, a reinforcing sheet may be wound around the base end side on which the grip is mounted.

The appearance sheet constituting the appearance exposed layer 10C is wound after the main body sheet and the reinforcing sheet are heated and the surface of the main body layer 10A is polished as a tubular body. That is, in order to keep the variation in hardness when the main body layer 10A is molded by the main body sheets 11 to 15 within a certain range, the surface of the main body layer is polished and then wound (wound around the surface of the polished portion). ). In FIG. 2, four appearance sheets 21, 22, 23, 24 are illustrated in order to make the structure of the appearance sheet easy to understand, but it is not necessary that all of them are wound, and any one of them is required. The appearance sheet may be wound (any combination is acceptable).

The winding position of the appearance sheet to be wound, the number of times of winding, the arrangement state of the reinforcing fibers, etc. are not particularly limited, but the appearance sheet 21 is wound over the entire length L of the shaft and the reinforcing fibers are wound. The appearance sheet 22 is wound around the tip end side of the shaft, and the reinforcing fibers are aligned in the shaft length direction. The appearance sheet 23 is wound around the intermediate region of the shaft. The appearance sheet 24, in which the reinforcing fibers are aligned in the axial length direction, is wound so as to be exposed from the grip on the rear end side of the shaft, and the reinforcing fibers are aligned in the axial length direction.

As described above, since the appearance sheet is wound for the purpose of showing the appearance, it may be wound around the portion where the appearance is desired to be improved. Further, since the main purpose is to show the appearance, it is preferable that the wall thickness is as thin as possible so as not to affect the basic performance of the shaft. Therefore, regarding the wall thickness, as shown in FIGS. 3A and 3B, it is preferable to wind the externally exposed layer 10C so that the wall thickness T is thinner than the wall thickness T1 of the main body layer 10A. .. For example, when winding a plain weave or braid for the purpose of appearance, it is preferable to wind it with a small number of plies such as about 1 ply, but if there is a purpose such as improving rigidity, a plurality of plies may be used. You may try to wind it.

Next, a shaft manufacturing process for molding the shaft with the arrangement pattern of the prepreg sheets as shown in FIG. 2 will be described with reference to FIG.
First, the first molding step is performed. In this first molding step, a mold release agent is applied to the core metal 50, and a prepreg sheet (main body sheets 11 to 15) and a reinforcing sheet 17 made of a high-temperature curing material are manually wound or sheet-rolled in order. It is mechanically wound using a machine, and a tightening tape (wrapping tape; not shown) is wound around the surface thereof. The tightening tape is wound mainly to secure the shape retention of the main body layer and to suppress the generation of voids, and the tape is in a state where the core metal 50 around which the prepreg sheet is wound is chucked. It is wound at a constant pressure using a wrapping machine.

Subsequently, the core metal around which the main body sheet, the reinforcing sheet and the tightening tape are wound is transported to a heating furnace and heat-treated, and the matrix resin is cured at the above-mentioned high curing temperature, and then removed. The core and the tightening tape are peeled off to form a tubular body layer 10A.

Subsequently, the surface of the tubular body layer 10A is polished. This polishing is performed to adjust the variation in hardness, and can be performed by wet belt sander polishing, hand polishing with sand paper, or the like. The surface of the portion around which the appearance sheet is wound may be roughened so as to improve the adhesion to the appearance exposed layer.

Subsequently, the second molding step is performed. This second molding step is a process for forming the externally exposed layer 10C on the main body layer whose surface has been polished. First, the main body layer 10A is fitted onto the core metal 50 which is the same as the first molding step. Then, as in the first molding step described above, a prepreg sheet made of a low-temperature curing material (any one of the appearance sheets 21 to 24 or a plurality thereof) is wound, and a tightening tape (wrapping tape) is wound around the surface thereof. .. In this case, in consideration of workability, it is preferable to externally fit the main body layer 10A to the same core metal before winding the appearance sheet, but the main body layer whose surface is polished has rigidity, and the appearance sheet has a rigidity. If it can withstand the pressing force of the rolling work, it may be fitted to the core metal from the time of winding the tightening tape.

Then, the appearance sheet and the core metal around which the tightening tape is wound are cured at the above-mentioned low curing temperature. Since the heating temperature in this second molding step is such that the low-temperature effect material which is the externally exposed layer 10C is cured, the high-temperature curing material constituting the main body layer 10A does not soften, and the shaft is stable. It can demonstrate its performance.

After that, the decentering and the tightening tape are peeled off to form the shaft 10. When the tightening tape is peeled off, the surface thereof has spiral irregularities, so that fine polishing is performed to smooth the surface. A clear layer may be formed on the smoothed surface, and a decorative layer such as characters and figures may be formed if necessary.

According to the shaft having the above configuration, after adjusting the variation in shaft hardness in advance, it is possible to improve the appearance appearance while improving the performance of the shaft by additionally molding the material for appearance. Become. That is, since the appearance exposed layer 10C does not have fiber breakage or the like, the appearance of the surface can be improved.

Further, the appearance exposed layer 10C is not polished (the outermost layer having a high effect as a shaft is not scraped) to adjust the hardness variation as in the conventional case, or the surface is roughened for painting. Polish to a fine degree. In this case, in performing fine polishing to the extent that the surface is roughened, for example, high-strength reinforcing fibers having high strength development (for example, T1100G and M40X manufactured by Toray Industries, MR70 manufactured by Mitsubishi Chemical Co., Ltd. (both fiber names), Boron). It is possible to ensure the performance even by using a special prepreg sheet that is a combination of a tungsten powder with a heavy specific gravity and a low-temperature curable resin (such as a prepreg fused with a metal wire such as). Further, in the double molding method as described above, in order to improve the crushing strength, it is possible to dispose a thin-count material that is usually scraped by polishing in the outermost layer.

The externally exposed layer having the above-described configuration can be formed on the surface of a general steel shaft. Regarding the externally exposed layer, considering the adhesion to the steel shaft surface and the difficulty of peeling, the low temperature curable resin material as described above (100 ° or less, preferably around 70 ° to 80 °). It is preferably composed of a resin material that cures). Further, even in such a configuration, it is preferable to roughen the surface of the prepreg sheet constituting the externally exposed layer before winding it.

In this case, regarding the adhesion between the roughened state of the surface of the steel shaft and the above-mentioned low-temperature curable resin material used as the appearance material, it is verified whether or not peeling occurs by changing the roughened state of the surface. did. No peeling was found when the exterior material was wound with one ply or more. Therefore, when the peeling condition when partially wound on the surface of the steel shaft was verified with a plurality of samples having different rough surface conditions, the surface was verified. When the roughness (Ra value) was 0.2398, slight peeling was found in a small part. Therefore, in the case of partial winding (1 ply or more may be used), it is desirable to form the externally exposed layer in a state where the Ra value of the surface of the corresponding portion of the steel shaft is roughened to 0.25 or more. That is, in such a configuration, it is possible to form an externally exposed layer having good adhesion without using a primer or the like.

If the main body layer was the above-mentioned high-temperature curable resin material, the peeling phenomenon did not occur even if the surface was not roughened.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be variously modified. The present invention is characterized by a shaft of a golf club, and can be applied not only to a wood-type golf club but also to an iron-type golf club and a putter shaft.
Further, the above configuration can be applied not only to the shaft of a golf club but also to a tubular body such as a fishing rod, a rod holder, and a ball net.

1 Golf club 10 Shaft 10A Body layer 10B Reinforcement layer 10C Appearance exposed layer 11 to 15 Body sheet 17 Reinforcement sheet 21 to 24 Appearance sheet 30 Head 40 Grip 50 Core metal

Claims (8)

In a golf club equipped with a shaft made of fiber reinforced plastic,
The shaft is characterized by having a main body layer arranged radially inside and formed of a high temperature curing material, and an externally exposed layer arranged radially outside and formed of a low temperature curing material. club. The golf club according to claim 1, wherein the surface of the main body layer is polished, and the externally exposed layer is disposed on the polished portion. The golf club according to claim 1 or 2, wherein the externally exposed layer is thinner than the main body layer. The golf club according to any one of claims 1 to 3, wherein the appearance exposed layer is arranged over the entire length of the shaft. A golf club with a shaft that is wound around at least a portion of a steel tubular body and has an externally exposed layer formed by a fiber reinforced resin prepreg sheet.
The steel tubular body is a golf club characterized in that the surface of a portion around which the prepreg sheet is wound is roughened. The golf club according to claim 5, wherein the roughened portion of the steel tubular body is roughened to a Ra value of 0.25 or more. The first molding process, in which a prepreg sheet made of a high-temperature curing material is wound around a core metal and heated to form a tubular body layer,
A polishing step of polishing the surface of the main body layer formed by the first molding step, and
A second molding step of winding a prepreg sheet made of a low-temperature curing material around the main body layer whose surface has been polished and heating it to form an exposed appearance layer.
A method for manufacturing a shaft of a golf club, which comprises. The method for manufacturing a golf club shaft according to claim 7, wherein after the polishing step, the tubular main body layer is fitted onto a core metal and a prepreg sheet made of the low-temperature curing material is wound around the core metal. ..