JPH0622365Y2 - Golf club shaft made of fiber reinforced plastic - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to improvement of a shaft for fiber golf reinforced plastic golf clubs.

<Prior Art and Problems> In steel shafts for golf clubs, in order to adjust the flex tone of the shaft, a predetermined portion of the shaft is thinly drawn according to the characteristics to be adjusted (second moment of area I EI is reduced by making it smaller) and a hard point is attached.

Therefore, in the fiber reinforced plastic golf club shafts, there are some kinds of feeling such as tone, middle tone, and hand tone in terms of feeling, but as in the steel golf club shafts, the key points are clear. Not.

Conventionally, in a shaft for a fiber reinforced plastic golf club, in order to set a kick point, a resin impregnated sheet for adjusting a kick point having a fiber direction of 0 ° with respect to an axis is provided from the head side to the middle of the shaft and from the grip side to the shaft. 2 sheets in the middle, 20 cm to 6 between both sheets
It is proposed to wind the sheet at a distance of 0 cm so that the EI of the portion between these sheets is smaller than that of the other portions.

However, in the conventional fiber reinforced plastic golf club shaft described above, a step is formed at both ends of the low EI portion, which makes surface finishing (grinding the surface and applying resin coating to the ground surface) difficult, or
The process for filling the step is required, the manufacturing man-hour is increased, the EI of the shaft is greatly changed in the low EI part, and the bending stress is concentrated remarkably. The edge of the kick point adjusting sheet is located in the middle of the shaft. Therefore, there is a disadvantage that the edge of the shaft may be peeled off due to the repeated bending deformation of the shaft and the kick point may change.

An object of the present invention is to provide a shaft for a fiber reinforced plastic golf club that can maintain the linearity of the outer surface, well suppress the concentration of bending stress, and set a desired stable kick point.

<Structure of the Invention> The fiber reinforced plastic golf club schaft according to the present invention is a filament reinforced plastic golf club schaft that can be formed by winding filaments at a predetermined angle. The wrapping angle (the angle on the acute angle side between the filament and the shaft axis) is 45 ° or less, and is larger than the wrapping angle of the adjacent filament by 5 ° or more.

In the above, the reason why the filament winding angle is limited to 45 ° or less is that at 45 ° or more, the tensile force that can act on the filament is decreased, the tensile bending strength is significantly reduced, and it is disadvantageous in bending strength. is there.

<Description of Embodiments> The present invention will be described below with reference to the drawings.

In FIG. 1, A is a hollow golf club shaft made of fiber reinforced plastic that can be molded by winding a filament at a predetermined angle, where 1 is a grip part, 2 is a tip part, and 3 is a shaft body part. Shown respectively. B is the low EI portion for the kick point, and the filament wrap angle (the angle on the acute angle side between the filament and the shaft axis) is 45 ° or less and 5 ° or more than the wrap angle of the adjacent filament. E by increasing
Is small. The length l of this low EI part is 2 to 40 cm
There is. Regarding the tensile bending strength of this low EI portion, since the wrap angle of the filament is 45 ° or less and the filament can well bear the tensile force in the shaft axis direction, the tensile bending strength can be increased by increasing the wrap angle of the filament. Nevertheless, it can be held sufficiently.

In FIG. 1, when M is the bending moment acting on the low EI portion, the maximum tensile bending stress τ _max is (Where d is the maximum diameter of the low EI portion), and letting the allowable tensile bending strength of the low EI portion be F, the above conditions for the filament winding angle of 45 ° or less are τ _max <F with sufficient safety. Is satisfied.

In the above, the deflection angle θ per unit length of the low EI part is And the deflection angle of the entire low EI part is Is.

Therefore, in order for the low EI portion to function as a clear kick point, it is necessary to set a predetermined value under a predetermined bending moment (a bending moment that acts based on the head weight at the time of swing). The length l of the part is set to 2 to 40 cm so as to meet this requirement.

Thus, when the filament winding angle of the low EI portion is 45 °, E of the low EI portion is E _min , and the length l is 1 _min.
When the filament wrap angle of the low EI portion is minimized (when the filament angle is 5 ° larger than the wrap angle of the adjacent filament), E of the low EI portion is E _max and length l is 1 _max.
If so, between these Therefore, the relationship between the length 1 of the low EI part and the Yang rate E is as much as possible. It is desired to give a relationship.

In the above, the low EI portion can be provided at any position in the shaft body portion.

The shape of the shaft is usually a tapered shaft whose diameter is gradually reduced from the grip side to the tip.
The wrap angle of the filament can be constant over the entire length, or can be made smaller as it reaches the tip side of the shaft. The range of the wrapping angle is 25 ° to 5 ° except for the low EI portion. The length of the shaft is usually 80-120cm, and the length of the grip is usually 20c.
m, the length of the tip is usually 2 to 10 cm. The outer diameter of the grip end of the shaft is usually 13 to 17 mm, and the outer diameter of the tip of the shaft is usually 6 to 10 mm. The thickness of the hollow shaft gradually increases from the grip side to the tip side, and the thickness on the grip side is usually 0.5 to 3.0 m.
m, the thickness of the tip side is 1.0 to 4.0 mm.

The filament winding method is used for molding the shaft. Epoxy resin, unsaturated polyester resin, phenol resin, etc. can be used for the resin, and for filament, one or more kinds of carbon, aramid, polon, silicon carbide, glass fiber, alumina fiber, stainless fiber, amorphous fiber are used. Can be used.
The fiber content in FRP is usually 60 to 80%.

The shaft of the present invention can be implemented in either one-layer winding or 2-3 layer structure.

In the case of one-layer winding, the wrap angle of the filament other than the low EI portion is preferably 7 to 22 °, and the wrap angle of the filament in the low EI portion is preferably 35 ° or less.

In the case of a two- to three-layer structure, the structure other than the outermost layer has a normal structure (eg, prepreg sheet is sushi-wound, winding with a constant winding angle over the entire length), and only the outermost layer has low E.
The I portion may be provided, and the decrease in the bending strength of the low EI portion due to the increase in the filament winding angle can be sufficiently mitigated because the decrease is limited to the outermost layer. The attachment angle can be selected within the range of 45 ° or less.

Next, an embodiment of the present invention will be described.

<Example> Single-layer winding, and in FIG.
₁ : 978 mm, length of grip part (uniform outer diameter) L ₂ : 100 m
m, the length L _{3 of} the tip (uniform outer diameter): 220 mm, and the wall thickness and outer diameter are r ₁ = 13.00 in FIG. 2B (left side view) and FIG. 2C (right side view). mm, r ₂ = 15.2 mm, r ₃
= 9.3 mm, r ₄ = 4.5 mm. Carbon long fibers are used as the fibers, and a bisphenol type epoxy resin composition is used as the resin. The heating conditions are 150 ° C. and 8 hours, and the fiber content is 70%.
It was set to% by weight. Low EI part is 300mm from the tip of the shaft
The length of the filament is 60 mm at the position of, and the winding angle of the filament is as shown in FIG. 2A, 7 to 9 ° at the portion of length L ₄ = 300 mm (to the winding angle as the winding progresses). The same applies hereinafter), low EI part (length 60 mm)
18 to 22 ° at L ₀ , 13 to 22 ° at L ₅ = 618mm
And Finally, after centering, the outer surface was polished by centerless processing.

<Embodiment 2> It has a two-layer structure, and the dimensions of each part are shown in FIGS. 3A and 3B.
(Left side view) and FIG. 3C (right side view), L ₀ ′
_{= 40mm, L 4 '= 260mm} , L 5' = 843mm, r 1 '= 13.3
mm, r ₂ ′ = 14.3 mm, r ₃ ′ = 15.4 mm, r ₄ ′ = 4.0 m
m, r ₅ ′ = 6.0 mm, L ₆ ′ = 8.5 mm. The inner layer is made of high-carbon winding with a constant wrap angle of 45 ° (elastic modulus: 40 t / mm ² , tensile strength: 220 kg / mm ² ) and the outer layer is made of high-strength carbon fiber (elastic modulus 24 t / mm ² , tensile strength). Strength: 380 kg / mm ² ) was winded at the winding angle shown in FIG. 3A. The winding angle of the low EI portion L ₀ ′ is 15
-17 °, length 40 mm. Other resins and processing conditions are the same as in Example 1.

<Embodiment 3> It has a three-layer structure, and the dimensions of each part are shown in FIGS. 4A and 4B.
(Left side view) and FIG. 4C (right side view), L ₀ ″
= 80mm, L ₄ ″ = 300mm, L ₅ ″ = 763mm, r ₁ ″ = 13.3
mm, r ₂ ″ = 13.6mm, r ₃ ″ = 14.6mm, r ₄ ″ = 15.4m
m, r ₅ ″ = 4.0mm, r ₆ ″ = 4.3mm, r ₇ ″ = 6.3mm, r
₈ ″ = 8.5 mm. The first layer is formed by winding a prepreg of boron long fibers so that the fibers are aligned in the shaft axis direction, and the second layer is aramid long fibers (elastic modulus:
13 t / mm ² , tensile strength: 280 kg / mm ² ) and high carbon fiber were mixed at a mixing ratio of 1: 3 and were winded at a winding angle of 45 °. The outermost layer was winded at a wrapping angle shown in FIG. 4A with aramid long fibers and medium elastic carbon fibers (elastic modulus: 30 t / mm ² , tensile strength: 420 kg / mm ² ) at a mixing ratio of 1: 3. The low EI portion was provided only in the outermost layer over a length of 80 mm at a constant wrap angle of 18 °.
In addition, the resin and processing conditions are the same as in Example 1.

<Effects of the Invention> As described above, in the fiber-reinforced plastic golf club shaft according to the present invention, when the low EI portion for the kick point is attached by increasing the winding angle of the filament, the winding angle is 45 °. Since it is set as follows, the bending strength of the shaft can be sufficiently maintained. And even if the winding angle is limited in this way, the length of the low EI portion is 2 to 40 cm.
Therefore, the bending angle of the shaft due to the bending moment can be sufficiently increased in the low EI portion, and a sharp kick point can be provided.

In addition, since the kick point and the filament adjacent to this point are continuous, the change in EI can be made sufficiently slower than that of the conventional example using the kick point adjusting sheet, and the stress concentration can be relieved well. Since the outer surface can be made linear without any step, the surface can be easily ground and the ground surface can be easily coated with resin.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a shaft for a fiber reinforced plastic golf club according to the present invention, FIG. 2A is a front view showing an embodiment of the shaft of the present invention, and FIGS. 2B and 2C are FIG. A left side view and right side view, FIG. 3A is a front view showing another embodiment of the present invention, FIG. 3B and FIG. 3C are left side view and right side view of FIG. 3A, FIG. 4A is a front view showing another embodiment of the present invention, FIG. 4B and FIG.
FIG. C is a left side view and a right side view of FIG. 4A. In the figure, B is the low EI part.

Claims (1)

[Scope of utility model registration request] 1. A filament wrap angle (a sharp angle side between filament and shaft axis) of a length 2-40 cm portion of a golf club shaft made of fiber reinforced plastic that can be molded by winding the filament at a predetermined angle. Angle) is 45 ° or less, and is 5 ° or more greater than the winding angle of the adjacent filament, a fiber reinforced plastic golf club shaft.