JP7516952B2 - Method for manufacturing golf club shaft - Google Patents

Description

The present invention relates to a method for manufacturing a golf club shaft.

Generally, golf club shafts made of fiber-reinforced resin are manufactured through the following process (see, for example, Patent Document 1 below).

First, the prepreg, which is made by impregnating reinforcing fibers with a matrix resin, is cut into a specified shape (cutting process).

Next, the cut prepreg is wound around a mandrel, which is the core material. This forms a wound body with the prepreg wound around the mandrel (winding process).

Next, the wound body is heated. This heating hardens the matrix resin of the wound body, resulting in a hardened laminate (hardening process).

Next, the mandrel is pulled out from the cured laminate (removal process).

Next, any irregularities remaining on the outer surface of the cured laminate are smoothed by polishing (polishing process), and then the outer surface of the cured laminate is painted (painting process) to obtain the shaft.

Next, the product name, brand logo, and other display parts are formed on the outer surface of the shaft by printing, transfer, etc.

Patent No. 6601583

Conventional manufacturing methods require many steps to produce golf club shafts, and there is a need to improve productivity.

The present invention was devised in light of the above-mentioned circumstances, and its main objective is to provide a method for manufacturing golf club shafts that can improve productivity.

The present invention is a method for manufacturing a golf club shaft, which includes a preparation step of preparing a shaft body using a fiber-reinforced resin, an attachment step of attaching a surface layer material including a heat-shrinkable film substrate with a display unit to the outer circumferential surface of the shaft body, and a fixing step of heat-shrinking the surface layer material and closely fixing the surface layer material to the outer circumferential surface of the shaft body.

In another aspect of the present invention, the surface layer may be formed into a cylindrical shape before being attached to the shaft body.

In another aspect of the present invention, the shaft body may be a cured prepreg laminate formed by stacking prepregs.

In another aspect of the present invention, at least a portion of the outer circumferential surface of the shaft body may have an unpolished portion, and in the mounting step, the surface layer may be mounted so as to cover at least a portion of the unpolished portion.

In another aspect of the present invention, at least a portion of the outer circumferential surface of the shaft body may have an unpainted portion, and in the mounting step, the surface material may be mounted so as to cover at least a portion of the unpainted portion.

In another aspect of the present invention, the shaft body includes a front surface on which the golfer can see when the golfer takes his stance and a back surface on which the golfer cannot see, the surface material includes a joint formed by overlapping and joining the film base material, and the mounting step may include mounting the joint so that it is located on the back surface of the shaft body.

In another aspect of the present invention, a convex pattern extending in a spiral shape is formed on the outer circumferential surface of the shaft body, and in the mounting process, the surface layer may be mounted so as to cover at least a portion of the convex pattern.

In another embodiment of the present invention, the thickness of the film substrate may be 10 to 100 μm, preferably 30 to 100 μm, more preferably 30 to 80 μm, and even more preferably 30 to 50 μm.

In another aspect of the present invention, the shaft body may be an uncured prepreg laminate made by stacking prepregs.

Another aspect of the present invention is a method for manufacturing a golf club, which includes a step of attaching a golf club head to a golf club shaft manufactured by any of the methods for manufacturing a golf club shaft described above.

By adopting the above process, the present invention can improve the productivity of golf club shafts.

FIG. 2 is a perspective view of a shaft body according to the first embodiment. FIG. 2 is a perspective view of the front side of the surface layer material of the first embodiment. 3 is an exploded perspective view of the surface material of FIG. 2 as seen from the back side. FIG. FIG. 2 is a perspective view of the shaft body with the surface material attached thereto. 1 is a perspective view of a golf club shaft according to a first embodiment. FIG. FIG. FIG. 7 is a top view of the golf club of FIG. 6. FIG. 13 is a perspective view showing a first modified example of the shaft body. FIG. 11 is a partial cross-sectional view of another example of a shaft body. FIG. 11 is a partial cross-sectional view of a modified shaft body with a surface layer attached thereto. FIG. 11 is a partial cross-sectional view of a modified shaft body with a surface layer material tightly fixed thereto. 13A to 13C are perspective views illustrating a manufacturing method of a golf club shaft according to a second embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
It should be understood that the drawings include exaggerated expressions and expressions different from the dimensional ratio of the actual structure in order to facilitate understanding of the present invention. In addition, when there are multiple embodiments, the same or common elements are given the same reference numerals throughout the specification, and duplicated explanations are omitted. Furthermore, the specific configurations shown in the embodiments and drawings are for understanding the contents of the present invention, and the present invention is not limited to the specific configurations shown in the drawings.

[First embodiment]
The method for manufacturing a golf club shaft according to the present embodiment includes a preparation step, a mounting step, and a fixing step, each of which will be described below in order.

[Preparation process]
Fig. 1 shows a perspective view of a shaft body 10. As shown in Fig. 1, in a preparation step, a shaft body 10 using a fiber reinforced resin is prepared. The shaft body 10 of this embodiment is, for example, in the shape of a hollow pipe, and is formed in a substantially tapered shape toward one end.

The shaft body 10 is prepared, for example, through the cutting process, winding process, curing process, and removal process described above. That is, the shaft body 10 of this embodiment is prepared as a cured product obtained by curing a prepreg laminate in which prepregs (not shown) are stacked. The fiber reinforced resin that constitutes the shaft body 10 is not particularly limited, but for example, carbon fiber reinforced plastic (CFRP) is suitable.

The shaft body 10 of this embodiment has not been subjected to the polishing process described above. Therefore, at least a portion (in this embodiment, the entirety) of the outer circumferential surface 10a of the shaft body 10 is an unpolished portion, which is an unpolished surface.

The shaft body 10 prepared in the preparation process of this embodiment is not subjected to a painting process. Therefore, at least a portion (in this embodiment, the entirety) of the outer circumferential surface 10a of the shaft body 10 of this embodiment is left unpainted.

[Mounting process]
In the mounting step, a surface layer material 20 as shown in Fig. 2 is mounted on the outer circumferential surface 10a of the shaft body 10 prepared in the preparation step. The surface layer material 20 is formed to include a heat-shrinkable film base material. As shown in Fig. 2, the surface layer material 20 of this embodiment is formed into a cylindrical shape in advance before being mounted on the shaft body 10.

As shown in FIG. 3, the cylindrical surface layer material 20 is formed by overlapping and bonding both side portions 25a, 25a of a strip-shaped film substrate 25. For example, a solvent-based or urethane resin-based adhesive is used for bonding. Therefore, in the surface layer material 20 of this embodiment, a bonding portion 22 is formed by overlapping and bonding the film substrates 25 to each other. This bonding portion 22 extends, for example, along the longitudinal direction of the surface layer material 20, which corresponds to the axial direction of the shaft body 10.

It is desirable that the inner diameter of the cylindrical surface layer 20 be slightly larger than the outer diameter of the shaft body 10 so that the shaft body 10 can be inserted inside.

[Film substrate]
The film substrate 25 can be made of various film materials as long as they have heat shrinkability.

A resin film substrate is suitable as the film substrate 25. For example, a film made of one or a mixture of two or more selected from polyester resins such as polyethylene terephthalate, polyolefin resins such as polyethylene and polypropylene, polystyrene resins such as styrene-butadiene copolymers, and thermoplastic resins such as polyvinyl chloride can be used as the resin film substrate.

In addition to a laminated film in which two or more types of resin films are laminated, the film substrate 25 may also be a composite film in which a nonwoven fabric, a metal deposition layer, a foam layer, or the like is laminated to a resin film.

In particular, from the viewpoints of flexibility and stretchability, a polyethylene terephthalate-based or polystyrene-based resin film is suitable for the film substrate 25. The film substrate 25 may be transparent or colored.

The thickness of the film substrate 25 is not particularly limited, but is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, and is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm.

[Display]
The surface layer 20 is formed with a display section 23. The display section 23 is for displaying various information such as the manufacturer name, trademark, flex, etc. of the golf club shaft. The display section 23 may include not only characters but also, for example, decorative patterns, figures, etc. The display section 23 is formed, for example, on one side of the film substrate 25 by various means such as gravure printing or flexographic printing.

As is clear from FIG. 3, it is preferable that the display section 23 is formed on the surface material 20 at a position opposite the joint section 22. In this example, the display section 23 is separated from the joint section 22 by an angle of 180° around the cylindrical axial center line.

[Attaching surface material to shaft body]
4 shows a temporary assembly 30 in which the surface layer material 20 is attached to the shaft body 10. In this embodiment, the temporary assembly 30 is obtained by inserting the shaft body 10 into the cylindrical surface layer material 20. In another aspect, the temporary assembly 30 may be prepared using a sheet-like surface layer material 20. In this case, the sheet-like surface layer material 20 is wrapped around the outer circumferential surface 10a of the shaft body 10, and both ends of the surface layer material 20 are joined. In this way, the surface layer material 20 may be formed into a cylindrical shape on the shaft body 10.

In addition, the surface layer material 20 in this embodiment has a length that is almost equal to the entire length of the shaft body 10. In other aspects, the surface layer material 20 may be shorter or longer than the entire length of the shaft body 10. Furthermore, the surface layer material 20 may be divided into multiple pieces in the axial direction of the shaft body 10.

[Fixation process]
In the fixing step, the surface layer material 20 is thermally shrunk to closely adhere and fix the surface layer material 20 to the shaft body 10. The fixing step is performed, for example, by heating the temporary assembly 30 to a preset temperature. Heating can be performed in a variety of ways. For example, the temporary assembly 30 can be heated in a hot air chamber or steam chamber adjusted to a predetermined temperature. The heating temperature is appropriately set in accordance with the film substrate 25. When the film substrate 25 is, for example, PET, the atmospheric temperature in the chamber is preferably about 160 to 180°C.

The surface layer 20 of the temporary assembly 30 is thermally shrunk by heating and adheres firmly to the outer circumferential surface 10a of the shaft body 10. This produces the golf club shaft 1 shown in FIG. 5. This golf club shaft 1 includes a shaft body 10 made of fiber-reinforced resin and a surface layer 20 that is thermally shrunk and adheres tightly to the outer circumferential surface 10a (shown in FIG. 1) of the shaft body 10, and the surface layer 20 is provided with a display section 23.

As described above, according to the manufacturing method of the golf club shaft of this embodiment, for example, it is possible to completely eliminate the polishing process and the painting process or to simplify some of them. Therefore, the manufacturing method of this embodiment can improve the productivity of the golf club shaft 1.

In this embodiment, the surface layer 20 is attached so as to cover at least a part of the unpolished portion of the shaft body 10. In general, the surface roughness of the shaft body 10, which is made of a cured prepreg laminate, is large. In this embodiment, in order to utilize the surface characteristics of the shaft body 10 as is, an unpolished portion that has not been intentionally polished is left on the outer circumferential surface 10a of the shaft body 10. This allows the fine irregularities on the surface of the unpolished portion of the shaft body 10 to bite into the inner circumferential surface of the heat-shrunk surface layer 20, effectively preventing misalignment between the shaft body 10 and the surface layer 20.

From the above perspective, it is desirable that the ten-point average roughness (Rzjis) of the roughness curve measured along the axial direction of the outer circumferential surface 10a of the shaft body 10 is 3 μm or more, more preferably 4 μm or more, and even more preferably 4.5 μm or more.

[Application to golf clubs]
Fig. 6 shows a front view of a golf club 100 manufactured using the golf club shaft 1 of Fig. 5. Fig. 7 shows a top view of the golf club 100 of Fig. 6. The golf club 100 can be manufactured by a golf club manufacturing method including a step of attaching a golf club head 40 to the golf club shaft 1 manufactured by the manufacturing method described above. The golf club 100 of this embodiment includes the golf club shaft 1, the golf club head 40 fixed to one end side of the golf club shaft 1, and a grip 50 attached to the other end side of the golf club shaft 1.

In FIG. 6, the golf club 100 is in a reference state. In this specification, the reference state of the golf club 100 is defined as a state in which the score lines 42 formed on the face 41 of the golf club head 40 are parallel to the horizontal plane HP, and the golf club head 40 is placed on the horizontal plane HP. In the reference state, the shaft axis center line CL is disposed within a reference vertical plane (not shown). The reference vertical plane is a plane perpendicular to the horizontal plane HP.

Returning to FIG. 1, the shaft body 10 of this embodiment includes a front surface 10A that is visible to the golfer when the golfer is in stance, and a back surface 10B that is not visible to the golfer. For example, since the shaft body 10 of this embodiment is obtained by laminating prepregs, it may not be completely isotropic due to the presence of spines where the prepregs overlap. When assembled into the golf club head 40, such a shaft body 10 is managed so that it is used in a specific orientation. As a result, the above-mentioned front surface 10A and back surface 10B of the shaft body 10 are specified in advance. Note that FIG. 1 shows a mark 10b as an optional element that indicates the center of the front surface 10A of the shaft body 10.

In this specification, the surface 10A of the shaft body 10 is defined as a surface that is located above the plane P (side A in Figs. 6 and 7) that passes through the shaft axis center line CL and is perpendicular to the paper surface of Fig. 6, with reference to Figs. 6 and 7. On the other hand, the back surface 10B of the shaft body 10 is defined as a surface that is located below the plane P (side B in Figs. 6 and 7).

In this embodiment, as shown in FIG. 6, the joint 22 of the surface layer 20 is attached so as to be located on the back surface 10B of the shaft body 10. With such a golf club shaft 1, when a golfer holds the golf club 100, the joint 22 of the surface layer 20 is not visible. Therefore, the golf club shaft 1 of this embodiment can improve the appearance performance of the golf club 100.

On the other hand, in the surface material 20 of this embodiment, the display portion 23 is provided at a position opposite the joint portion 22 in the circumferential direction of the surface material 20. Therefore, when a golfer holds the golf club 100, the display portion 23 that is intended to impress the golfer can be placed in the golfer's field of vision (see FIG. 7). Therefore, the golf club shaft 1 of this embodiment can improve the appearance performance of the golf club 100.

[Modification of Shaft Body]
Fig. 8 shows a perspective view of a modified shaft body 10. Fig. 9 is a partial cross-sectional view taken along the shaft axial center line CL of the shaft body 10 of Fig. 8. In this modified example, the shaft body 10 is a cured product obtained by curing a prepreg laminate, and a spirally extending convex pattern 10c is formed on the outer circumferential surface 10a.

The convex pattern 10c is formed, for example, after the winding process described above, by winding a wrapping tape (not shown) in a spiral shape around the outside of the wound body while applying tension (tape wrapping process), and then hardening the wound body together with the wrapping tape. Such wrapping tape helps prevent the prepreg from coming undone, etc., and helps maintain the shape of the wound body. Meanwhile, after the wrapping tape is removed, a spiral wrapping tape winding mark remains on the outer circumferential surface 10a of the shaft body 10. In this example, the wrapping tape winding mark is used as the convex pattern 10c.

As shown in FIG. 10, the surface layer 20 is attached to the shaft body 10 shown in FIG. 8 and FIG. 9 in the same manner as described above (attachment process). At this time, the surface layer 20 is attached so as to cover at least a portion of the convex pattern 10c. This results in a temporary assembly 30 in which the surface layer 20 is attached to the shaft body 10.

Next, the temporary assembly 30 is heated (fixing process). This causes the surface layer 20 disposed on the outside of the shaft body 10 to thermally shrink, and the surface layer 20 is tightly fixed to the shaft body 10.

The above steps result in the manufacture of a golf club shaft 1 as shown in Figure 11. In this golf club shaft 1, the spirally extending convex pattern 10c of the shaft body 10 is embedded into the inner peripheral surface of the surface layer 20, which in turn strengthens the bond between the shaft body 10 and the surface layer 20, which is particularly desirable in that it effectively prevents misalignment in the axial direction.

In a preferred embodiment, the height h of the convex pattern 10c on the shaft body 10 is preferably 20 μm or more, more preferably 25 μm or more. On the other hand, if the height h of the convex pattern 10c is excessively large, there is a risk of breakage of the surface layer 20. From this perspective, the height h of the convex pattern 10c is preferably 50 μm or less, more preferably 45 μm or less.

[Second embodiment]
12A to 12C are perspective views illustrating a manufacturing method of a golf club shaft according to the second embodiment. In the first embodiment, a cured shaft body 10 is prepared in the preparation step. The second embodiment differs from the first embodiment in that the shaft body 10 is an uncured prepreg laminate obtained by laminating prepregs.

As shown in FIG. 12(A), the shaft body 10 of this embodiment is prepared on a mandrel M, which is a core metal (preparation process). In other words, a number of prepregs 10P cut to a predetermined shape are wound around the mandrel M to form the uncured shaft body 10.

Next, as shown in FIG. 12(B), the surface layer material 20 is attached to the uncured shaft body 10 on the mandrel M (attachment process). In this example, the surface layer material 20 is also pre-formed into a cylindrical shape, and the shaft body 10 is inserted into it together with the mandrel M. This results in a temporary assembly 30 in which the surface layer material 20 is attached to the shaft body 10.

Next, this temporary assembly 30 is heated to a predetermined temperature in an oven or the like (fixing process). This causes the prepreg in the shaft body 10 to begin hardening. The surface layer material 20 also thermally shrinks, and is fixed tightly to the shaft body 10.

By completing the above steps, the golf club shaft 1 can be manufactured on the mandrel M as shown in FIG. 12(C). In this embodiment, the hardening of the shaft body 10 and the thermal shrinkage of the surface layer 20 are performed simultaneously, further improving the productivity of the golf club shaft 1. In addition, like the wrapping tape, the surface layer 20 holds the shaft body from the outside during hardening, preventing the prepreg from coming apart and helping to maintain its shape.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the specific disclosure above, and can be implemented with various modifications within the scope of the technical ideas described in the claims. For example, when the manufacturing method of this embodiment is used, a golf club shaft etc. such as the one shown below can be provided.

[Aspect 1]
A golf club shaft 1, comprising: a shaft body 10 made of fiber reinforced resin; and a surface layer 20 tightly fixed to an outer peripheral surface 10a of the shaft body 10 by thermal shrinkage, the surface layer 20 being provided with a display unit 23.

[Aspect 2]
In the above-mentioned aspect 1, the shaft body 10 is a cured product of a prepreg laminate in which prepregs are stacked, and at least a portion of the outer circumferential surface 10a has an unpolished portion that has not been polished, and the surface material 20 can cover at least a portion of the unpolished portion.

[Aspect 3]
In the above-mentioned aspects 1 or 2, a convex pattern 10c extending in a spiral shape is formed on the outer circumferential surface 10a of the shaft body 10, and the surface material 20 may cover at least a portion of the convex pattern 10c.

[Aspect 4]
In any one of the above-mentioned aspects 1 to 3, the shaft body 10 may be unpainted.

[Aspect 5]
In any of the above aspects 1 to 4, the shaft body 10 includes a front surface 10A which is a surface that the golfer can see when the golfer takes his/her stance, and a back surface 10B which is a surface that the golfer cannot see, and the surface material 20 has a joint 22 extending along the axial direction of the shaft body 10, and the joint 22 may be located on the back surface 10B of the shaft body 10.

[Aspect 6]
A golf club 100 comprising the golf club shaft 1 according to any one of the above aspects 1 to 5 and a golf club head 40.

Reference Signs List 1 Golf club shaft 10 Shaft body 10A Surface 10B of shaft body Back surface 10a of shaft body Outer circumferential surface 10c of shaft body Convex pattern 20 Surface layer 22 Joint 23 Display 25 Film substrate 40 Golf club head 100 Golf club

Claims (10)

A method for manufacturing a golf club shaft, comprising the steps of:
A preparation step of preparing a shaft body using a fiber reinforced resin;
a mounting step of mounting a surface layer material including a heat-shrinkable film substrate having a display unit on an outer circumferential surface of the shaft body;
and a fixing step of thermally shrinking the surface layer material to closely and securely fix the surface layer material to the outer circumferential surface of the shaft body,
the shaft body includes a front surface that is a surface visible to the golfer when the golfer sets up, and a back surface that is not visible to the golfer,
The surface layer material has a joint portion where the film base material is overlapped and joined,
The mounting step includes mounting the joint portion so as to be located on the back surface of the shaft body.
A method for manufacturing a golf club shaft. The method for manufacturing a golf club shaft according to claim 1, wherein the surface layer is preformed into a cylindrical shape prior to attachment to the shaft body. The method for manufacturing a golf club shaft according to claim 1 or 2, wherein the shaft body is a cured prepreg laminate formed by laminating prepregs. At least a portion of the outer circumferential surface of the shaft body includes an unpolished portion that is not polished,
The method for manufacturing a golf club shaft according to claim 3 , wherein in the attaching step, the surface material is attached so as to cover at least a part of the unpolished portion. At least a portion of the outer circumferential surface of the shaft body includes an unpainted portion that is not painted,
5. The method of manufacturing a golf club shaft according to claim 3, wherein in the attaching step, the surface material is attached so as to cover at least a part of the unpainted portion. A convex pattern extending in a spiral shape is formed on the outer circumferential surface of the shaft body,
6. The method for manufacturing a golf club shaft according to claim 1, wherein in the attaching step, the surface material is attached so as to cover at least a part of the convex pattern . 7. The method for manufacturing a golf club shaft according to claim 1, wherein the thickness of the film substrate is 10 to 100 μm . 3. The method for manufacturing a golf club shaft according to claim 1, wherein the shaft body is an uncured prepreg laminate obtained by laminating prepregs. A method for manufacturing a golf club shaft, comprising the steps of:
A preparation step of preparing a shaft body using a fiber reinforced resin;
a mounting step of mounting a surface layer material including a heat-shrinkable film substrate having a display unit on an outer circumferential surface of the shaft body;
and a fixing step of thermally shrinking the surface layer material to closely and securely fix the surface layer material to the outer circumferential surface of the shaft body,
A convex pattern extending in a spiral shape is formed on the outer circumferential surface of the shaft body,
In the mounting step, the surface material is mounted so as to cover at least a portion of the raised pattern.
A method for manufacturing a golf club shaft. A method for manufacturing a golf club, comprising the steps of:
a step of mounting a golf club head on a golf club shaft manufactured by the method for manufacturing a golf club shaft according to any one of claims 1 to 9,
A method for manufacturing a golf club.

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