Golf club shaft and golf club

Abstract

To provide a golf club shaft and golf club to be easily treated by a general golfer and, especially, an unexperienced or a beginner golfer.SOLUTION: A golf club shaft is obtained by allowing a plurality of layers of prepregs where reinforced fibers are impregnated with a thermosetting resin to be formed in a cylindrical shape and performing thermosetting. When a cross section orthogonal to an axial line of the golf club shaft is viewed, parts with a different thickness are at least partially formed in the whole length of the golf club shaft. An oscillation frequency in a first axial direction orthogonal to the axial line of the golf club shaft is different from an oscillation frequency in a second axial direction orthogonal to the first axis.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a golf club shaft and a golf club using the same.

Background Art

[0002] Instead of a steel golf club shaft, a golf club shaft made of FRP (Fiber Reinforced Plastics), which is obtained by winding a plurality of layers of prepreg impregnated with a thermosetting resin in reinforcing fibers such as carbon fiber and then thermosetting, is widely used. This golf club shaft is lightweight and easy to bend, and is particularly easy to handle even for ordinary golfers.

[0003] In a golf swing, by bending the golf club shaft in a direction parallel to the flight line of the ball from the take-back to the downswing and then allowing the bend to return, energy can be efficiently transmitted to the golf ball at impact, leading to an improvement in the flight distance and enabling good directionality of the flying ball. On the other hand, if the golf club shaft bends in a direction perpendicular to the flight line of the ball, not only does the flight distance decrease, but also a phenomenon called "toe down", where the golf club head drops, occurs. If the golf club shaft bends excessively in a direction perpendicular to the flight line of the ball, a phenomenon where the ball flies in an unintended direction (such as a slice) is likely to occur.

[0004] If the swing trajectory can be stabilized, it becomes easier to bend the golf club shaft in a direction parallel to the flight line of the ball. However, for ordinary golfers, especially inexperienced or beginner golfers, it is difficult to stabilize the swing trajectory, and it is extremely difficult to bend the golf club shaft in a direction parallel to the flight line of the ball. Therefore, there is a demand for a golf club shaft that is easy to handle for ordinary golfers, especially inexperienced or beginner golfers.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a golf club shaft and a golf club that are easy to handle for general golfers, particularly inexperienced or beginner golfers.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention provides a golf club shaft formed by cylindrically shaping and thermosetting a plurality of layers of prepregs impregnated with a thermosetting resin in reinforcing fibers, wherein at least a part of the entire length of the golf club shaft has portions with different wall thicknesses when viewed in a cross section perpendicular to the axis of the golf club shaft, and the frequency of vibration in a first axial direction perpendicular to the axis of the golf club shaft is different from the frequency of vibration in a second axial direction perpendicular to the first axis. A golf club shaft is provided. The present invention also provides a golf club characterized in that a club head and a grip are attached to the above golf club shaft.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a golf club shaft and a golf club that are easy to handle for general golfers, particularly inexperienced or beginner golfers.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

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Figure 11

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Embodiments of the present invention will be described. Aspect 1 in this embodiment is a golf club shaft formed by cylindrically shaping and thermosetting a plurality of layers of prepreg impregnated with a thermosetting resin in reinforcing fibers, wherein in at least a part of the entire length of the golf club shaft, when looking at a cross-section orthogonal to the axis of the golf club shaft, it has portions with different wall thicknesses, and the vibration frequency in the first axial direction orthogonal to the axis of the golf club shaft is different from the vibration frequency in the second axial direction orthogonal to the first axis. It is a golf club shaft characterized by this.

[0011] Aspect 2 in this embodiment is the golf club shaft according to Aspect 1, wherein the vibration frequency in the first axis is 1.03 to 1.15 times the vibration frequency in the second axis.

[0012] Aspect 3 in this embodiment is the golf club shaft according to Aspect 1 or Aspect 2, wherein in at least a part of the entire length of the golf club shaft, it has a thick wall portion with a relatively thick wall thickness and a thin wall portion with a relatively thin wall thickness. The thick wall portion is located intersecting the first axis, the thin wall portion is located intersecting the second axis, and the vibration frequency in the first axis is greater than the vibration frequency in the second axis. It is a golf club shaft characterized by this.

[0013] Aspect 4 in this embodiment is the golf club shaft according to Aspect 3, wherein in a part of the entire length of the golf club shaft, it has the thick wall portion and the thin wall portion, and the thick wall portion and the thin wall portion are located within a range of a predetermined length from the end of the golf club shaft where the grip is attached in the golf club.

[0014] Aspect 5 in this embodiment is that in the above Aspect 3 or Aspect 4, the golf club shaft has a plurality of layers of prepregs in which reinforcing fibers are impregnated with a thermosetting resin. The prepregs include a plurality of layers of first prepregs and at least one layer of second prepregs. In a cross-sectional view perpendicular to the axis of the golf club shaft, the first prepregs circulate around the axis, and the second prepregs are located intersecting the first axis without circulating around the axis. It is a golf club shaft characterized by this.

[0015] Aspect 6 in this embodiment is a golf club characterized in that a club head is attached to one end of the golf club shaft according to any of the above Aspects 1 to 5, and a grip is attached to the other end.

[0016] FIG. 1 is a perspective view schematically showing the golf club shaft according to this embodiment, and FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1 schematically showing the golf club shaft according to this embodiment.

[0017] The golf club shaft 1 according to this embodiment is formed by winding a plurality of layers of prepregs 20 in which reinforcing fibers are impregnated with a thermosetting resin into a cylindrical shape and thermosetting them. As the reinforcing fibers, for example, various materials such as carbon fibers, alumina fibers, aramid fibers, glass fibers, tyrano fibers, carbon silicate fibers, and amorphous fibers can be used. As the thermosetting resin, for example, various materials such as epoxy resins, unsaturated polyester resins, phenolic resins, vinyl ester resins, and peak resins can be used.

[0018] The outer shape of the golf club shaft 1 is a tapered shape in which the diameter gradually increases from the small-diameter side at the tip to the large-diameter side at the hand. A club head (not shown) is attached to the small-diameter side end 11 of the golf club shaft 1, and a grip (not shown) is attached to the large-diameter side end 12 of the golf club shaft 1.

[0019] As shown in FIG. 2, when a first axis L1 orthogonal to the axis L of the golf club shaft 1 and a second axis L2 orthogonal to the axis L and the first axis L1 are set, in a cross-sectional view orthogonal to the axis L of the golf club shaft 1, the inner peripheral surface 3 of the cylindrical golf club shaft 1 has two flat surfaces 31 intersecting the first axis L1 and two arc surfaces 32 intersecting the second axis L2. The two flat surfaces 31 are positioned opposite to each other along the first axis L1, and the two arc surfaces 32 are positioned opposite to each other along the second axis L2. In a cross-sectional view orthogonal to the axis L of the golf club shaft 1, the shape of the outer peripheral surface 4 of the golf club shaft 1 is substantially circular. With the inner peripheral surface 3 and the outer peripheral surface 4 of the golf club shaft 1 having the above configuration, in the golf club shaft 1, a thick portion 5 intersecting the first axis L1 and a thin portion 6 intersecting the second axis L2 and having a thickness thinner than that of the thick portion 5 are formed.

[0020] The length W31 (the length in the direction of the second axis L2) of the flat surface 31 on the inner peripheral surface 3 of the golf club shaft 1 is not particularly limited. If this length W31 becomes relatively long, the difference between the thickness T5 of the thick portion 5 and the thickness T6 of the thin portion 6 becomes relatively large, and the difference between the vibration frequency in the direction of the first axis L1 and the vibration frequency in the direction of the second axis L2 tends to become large. On the other hand, if this length W31 becomes relatively short, the difference between the thickness T5 of the thick portion 5 and the thickness T6 of the thin portion 6 becomes relatively small, and the difference between the vibration frequency in the direction of the first axis L1 and the vibration frequency in the direction of the second axis L2 becomes small. Therefore, the length W31 of the flat surface 31 may be set according to the setting of the difference between the vibration frequency in the direction of the first axis L1 and the vibration frequency in the direction of the second axis L2 of the golf club shaft 1.

[0021] As shown in FIG. 2, the length W31 of one flat surface 31 of the golf club shaft 1 and the length W31 of the other flat surface 31 may be the same, but are not limited to this embodiment. For example, the length W311 of one flat surface 311 may be relatively long and the length W312 of the other flat surface 312(31) may be relatively short (see FIG. 3). When the lengths W311 and W312 of the two flat surfaces 31(311, 312) are different, in the golf club using the golf club shaft 1, the relatively short flat surface 312 is located on the heel side of the golf club head, and the relatively long flat surface 311 is located on the toe side of the golf club head. By attaching the golf club head to the small-diameter side end 11 of the golf club shaft 1, the golf club shaft 1 is more likely to bend toward the heel side of the golf club head along the first axis L1, so that a toe-down is more likely to occur. On the other hand, by attaching the golf club head to the small-diameter side end 11 of the golf club shaft 1 such that the relatively long flat surface 311 is located on the heel side of the golf club head and the relatively short flat surface 312 is located on the toe side of the golf club head, the golf club shaft 1 is more likely to bend toward the toe side of the golf club head along the first axis L1, so that a toe-down is less likely to occur. Therefore, according to the embodiment shown in FIG. 3, it is possible to provide an optimal golf club shaft 1 with respect to the bending direction along the first axis L1 according to the golfer's swing habit and the like.

[0022] In addition, in the present embodiment, it is preferable that the two flat surfaces 31 intersecting the first axis L1 are provided such that the center of the flat surface 31 (the center in the direction of the second axis L2) intersects the first axis L1 in a cross-sectional view orthogonal to the axis L of the golf club shaft 1 (see FIG. 2). However, the present invention is not limited to this aspect. For example, the flat surface 31 may be provided so as to intersect the first axis L1 at any position of the flat surface 31, and the flat surface 31 may intersect the first axis L1 at a position shifted in the direction of the second axis L2 from the center of the flat surface 31. As in the aspect shown in FIG. 4 where the two flat surfaces 31, 31 facing each other in the direction of the first axis L1 are non-parallel, one flat surface 31 may intersect the first axis L1 at a position shifted in the direction of the second axis L2 from the center of the first axis L1.

[0023] The golf club shaft 1 according to the present embodiment has a thick portion 5 intersecting the first axis L1 and a thin portion 6 intersecting the second axis L2, so that the frequency in the direction of the first axis L1 and the frequency in the direction of the second axis L2 can be made different. More specifically, the frequency in the direction of the first axis L1 may be larger than the frequency in the direction of the second axis L2 and may be 1.03 to 1.15 times the frequency in the direction of the second axis L2. Then, in a golf club in which a club head is attached to the small-diameter side end portion 11 of the golf club shaft 1 according to the present embodiment with the face surface facing the second axis L2, the golf club shaft 1 is easily bent in the direction of the second axis L2 (the swing direction of the golf club) and is difficult to be bent in the direction of the first axis L1. As a result, the golf club is stably bent in the swing direction, so that it can be made into a golf club that is easy to handle for general golfers whose swing trajectories are unstable, particularly inexperienced or beginner golfers.

[0024] In addition, in the present embodiment, the vibration frequency of the golf club shaft 1 may be a value measured using, for example, a shaft vibration frequency measuring device (manufactured by Fujikura Composite Co., Ltd., product name: Golf Club Timing Harmonizer). The method of measuring the vibration frequency is, for example, preparing a golf club with a club head attached to the small-diameter side end portion 11 of the golf club shaft 1 and a grip attached to the large-diameter side end portion 12, fixing a range of 178 mm (7 inches) from the grip end of the golf club toward the club head using the shaft vibration frequency measuring device, holding the golf club shaft 1 substantially horizontally, pushing down and displacing the club head vertically by hand, and then releasing the hand to allow free vibration, and measuring the number of vibrations per minute as the vibration frequency.

[0025] The thick portion 5 may be provided over the entire length of the golf club shaft 1 (from the large-diameter side end portion 12 to the small-diameter side end portion 11), or may be provided in a part of the entire length of the golf club shaft 1. When the thick portion 5 is provided in a part of the entire length of the golf club shaft 1, the thick portion 5 may be located relatively closer to the small-diameter side end portion 11 side, or may be located relatively closer to the large-diameter side end portion 12 side. Preferably, the thick portion 5 may be provided in a partial region extending from the large-diameter side end portion 12 to the small-diameter side end portion 11 of the golf club shaft 1 along the axis L (see FIG. 1), and may be provided in a partial region extending from the large-diameter side end portion 12 to the small-diameter side end portion 11 of the golf club shaft 1 along the axis L within a range that protrudes from the grip attached to the large-diameter side end portion 12.

[0026] The thickness T5 of the thick portion 5 and the thickness T6 of the thin portion 6 only need to have a difference such that the vibration frequency in the first axis L1 direction is greater than the vibration frequency in the second axis L2 direction. Preferably, the vibration frequency in the first axis L1 direction has a difference such that it is 1.03 to 1.15 times the vibration frequency in the second axis L2 direction. The thick portion 5 is formed by arranging a prepreg (the second prepreg 22) as described later (see FIG. 5). By adjusting the number of layers of the second prepreg 22 arranged, a difference can be formed between the thickness of the thick portion 5 and the thickness of the thin portion 6.

[0027] As shown in FIG. 5, when viewing a cross section orthogonal to the axis L of the golf club shaft 1, the prepreg 20 includes a first prepreg 21 provided so as to circulate around the axis L and a second prepreg 22 provided without circulating.

[0028] In the thick portion 5 of the present embodiment, as shown in FIGS. 5 and 6, the first prepreg 21 that circulates around the axis L is located on the inner peripheral surface 3 side and the outer peripheral surface 4 side, and the second prepreg 22 is sandwiched between these first prepregs 21. A flat surface 31 is formed by the first prepreg 21 located on the inner peripheral surface 3 side. On the other hand, in the thin portion 6 of the present embodiment, the first prepreg 21 that circulates around the axis L is located on the inner peripheral surface 3 side and the outer peripheral surface 4 side, and the second prepreg 22 is not sandwiched between these first prepregs 21. An arc surface 32 is formed by the first prepreg 21 located on the inner peripheral surface 3 side. The second prepreg 22 may be located on the inner peripheral surface 3 side (see FIG. 7) or on the outer peripheral surface 4 side (see FIG. 8). As long as the outer peripheral surface 4 of the golf club shaft 1 is substantially circular, the position where the second prepreg 22 is disposed is not particularly limited.

[0029] In the golf club shaft 1 according to the present embodiment, the number of turns (ply number) of the first prepreg 21 may be set as appropriate. For example, the number of turns (ply number) of the first prepreg 21 may be at least 1 turn (1 ply) or more. The number of sheets of the second prepreg 22 disposed may be set as appropriate according to the difference between the thickness of the thick portion 5 and the thickness of the thin portion 6. For example, the number of sheets of the second prepreg 22 disposed may be at least 1 sheet or more.

[0030] The total weight of the golf club shaft 1 according to this embodiment is not particularly limited. According to this embodiment, by having the thickness portion 5 that intersects the first axis L1, a golf club using the golf club shaft 1 can be made easy to handle for general golfers, especially inexperienced or beginner golfers. Therefore, the total weight of the golf club shaft 1 may be appropriately set within a range that makes it easy to handle for general golfers, especially inexperienced or beginner golfers. Note that the total weight of the golf club shaft 1 in this embodiment means the weight of the golf club shaft 1 that has been subjected to a painting process.

[0031] A method for manufacturing the golf club shaft 1 according to this embodiment will be described. Prepare a substantially tapered rod-shaped mandrel 7 (rod-shaped core metal) that tapers in diameter from one end 72 to the other end 71 and has a flat surface portion 73 within a predetermined length range in the direction from one end 72 to the other end 71 (see Fig. 9). Next, wind the first prepreg 21 around the rod-shaped mandrel 7 in order from the inner layer side (lower layer side) to the outer layer side (upper layer side) (see Fig. 10). The number of windings (ply number) of the first prepreg 21 may be at least one winding. Since the rod-shaped mandrel 7 has the flat surface portion 73, a flat surface 31 can be formed on the first prepreg 21 located on the inner peripheral surface 3 side. Then, arrange the second prepreg 22 on the first prepreg 21 located on the flat surface portion 73 of the rod-shaped mandrel 7 (see Fig. 11). When the first prepreg 21 is wound around the rod-shaped mandrel 7 having the flat surface portion 73, the first prepreg 21 is wound in a shape along the flat surface portion 73 on the flat surface portion 73 (see Fig. 10), and thus the outer peripheral surface 4 of the golf club shaft 1 cannot be made substantially circular as it is. By arranging the second prepreg 22 only on the first prepreg 21 located on the flat surface portion 73, a thick portion 5 intersecting the first axis L1 can be formed, and the outer peripheral surface 4 of the golf club shaft 1 can be made substantially circular. Subsequently, wind the first prepreg 21 further, thermoset it, and then pull out the rod-shaped mandrel 7. Thereby, the golf club shaft 1 according to the present embodiment can be manufactured. A painting process may be applied to the outer peripheral surface 4 of the golf club shaft 1 manufactured in this way.

[0032] According to the golf club shaft 1 according to the present embodiment, it has a thick portion 5 intersecting the first axis L1 and a thin portion 6 intersecting the second axis L2, the vibration frequency in the first axis L1 direction and the vibration frequency in the second axis L2 direction are different, and the vibration frequency in the first axis L1 direction is greater than the vibration frequency in the second axis L2 direction. As a result, the golf club shaft 1 is easily bent in the swing direction (second axis L2 direction) of the golf club using the golf club shaft 1 and is difficult to bend in the direction orthogonal to the swing direction (first axis L1 direction). As a result, there is an effect that it is easy to handle for general golfers whose swing trajectory is unstable, particularly inexperienced or beginner golfers.

[0033] The embodiments described above are described for ease of understanding of the present invention and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

Explanation of Signs

[0034] 1... Golf club shaft 3... Inner peripheral surface 31... Flat surface 32... Arc surface 4... Outer peripheral surface 5... Thick portion 6... Thin portion 20... Prepreg 21... First prepreg 22... Second prepreg L... Axis L1... First axis L2... Second axis

Claims

1. A golf club shaft, wherein at least a part of the entire length of the golf club shaft has portions with different wall thicknesses when viewed in a cross section orthogonal to the axis of the golf club shaft, and a vibration frequency in a first axial direction orthogonal to the axis of the golf club shaft is different from a vibration frequency in a second axial direction orthogonal to the first axis, characterized in that it is a golf club shaft.

2. The golf club shaft according to claim 1, characterized in that the vibration frequency in the first axis is 1.03 to 1.15 times the vibration frequency in the second axis.

3. At least a part of the entire length of the golf club shaft has a thick-walled portion with a relatively thick wall thickness and a thin-walled portion with a relatively thin wall thickness, the thick-walled portion is located intersecting the first axis, the thin-walled portion is located intersecting the second axis, The golf club shaft according to claim 1 or 2, characterized in that the vibration frequency in the first axis is greater than the vibration frequency in the second axis.

4. A part of the entire length of the golf club shaft has the thick-walled portion and the thin-walled portion, The golf club shaft according to claim 3, characterized in that the thick-walled portion and the thin-walled portion are located within a range of a predetermined length from an end of the golf club shaft where a grip is attached in the golf club.

5. The golf club shaft has a plurality of layers of prepregs impregnated with a thermosetting resin in reinforcing fibers, the prepregs include a plurality of layers of first prepregs and at least one layer of second prepregs, In a cross-sectional view orthogonal to the axis of the golf club shaft, the first prepreg circulates around the axis, and the second prepreg intersects the first axis without circulating around the axis, characterized in that it is a golf club shaft according to claim 3.

6. A golf club, characterized in that a club head is attached to one end of the golf club shaft according to claim 1 or 2, and a grip is attached to the other end.

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