JPH11347164A - Golf club shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make both right-hand and left-hand twist rigidity the same and to make the twist rigidity of a shaft uniform by arranging plural layers of respectively the same number of both bias layers of plus side and minus side in the angle of reinforcing fibers and arranging these bias layers in such a manner that the totals of the respective second moments of inertia of both bias layers coincide. SOLUTION: A golf club shaft 10 is formed from a tubular body laminated with fiber reinforced prepreg sheets formed by impregnating the reinforcing fibers with a synthetic resin. At this time, the plus bias layers 11, 14 and minus bias layers 12, 13 and straight layers 15, 16 which are respectively plural are successively arranged from the innermost layer to the outermost layer of the shaft 10. The straight layers are arranged on the small-diameter side of the heat connection side. For example, the carbon fiber prepreg sheets are used for the respective layers 11 to 17 and the angles of the respective reinforcing fibers in the respective plus bias layers 11, 14 and the respective minus bias layers 12, 13 are set at the same angles to each other within a range of +30 to 60 deg., -30 to 60, respectively with respect to the axis of the shaft 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club shaft, and more particularly to a golf club shaft made of a fiber reinforced resin such as carbon fiber, which is called a carbon shaft. This is to reduce the occurrence of warpage.

[0002]

2. Description of the Related Art In recent years, as a golf club shaft (hereinafter abbreviated as a shaft), a shaft made of a carbon fiber reinforced resin called a carbon shaft has been used by many players. Compared with steel shafts, this carbon shaft has a great degree of freedom in design, such as being able to significantly reduce weight and being able to set torsional rigidity and bending rigidity relatively freely. Therefore, it can respond to the needs of a wide range of golfers and is thus widely used.

As shown in FIG. 5, a shaft made of a fiber-reinforced resin such as a carbon shaft is formed by cutting a prepreg sheet in which a reinforcing fiber is impregnated with a resin into a strip shape, and one end in the axial direction (head connection side). Is formed by winding a required number of sheets around a tapered mandrel having a reduced diameter, and forming the mandrel after or before forming. The structure of the golf club shaft without a completed tubular body is
As shown in FIG. 6, several types of prepreg sheet layers are circumferentially stacked.

Specifically, generally, as shown in FIG.
The inner layer (core-side layer) is a bias layer 30 in which the reinforcing fibers are inclined with respect to the axis L, and plays a role in increasing the torsional rigidity and torsional strength of the shaft. On the other hand, the outer layer is a straight layer 31 in which the reinforcing fibers are parallel to the axis L, and plays a role of increasing the bending configuration and bending strength of the shaft.

According to the "Golf Rules" issued by the Japan Golf Association, regarding the uniformity of a golf club shaft, the bending rigidity must be constant in any circumferential direction.
It is stipulated that the torsional stiffness must be the same in both the left and right directions, and that the shaft must be substantially straight.

[0006] The bending rigidity can be made uniform by devising a single strip-shaped prepreg sheet so that it becomes just an integral number of revolutions, or by shifting the position of the seam for each layer. The bending stiffness is set to be uniform in the circumferential direction.

For uniformity of torsional rigidity, when a prepreg sheet having reinforcing fibers having an angle of + α ゜ with respect to the axis L is used, a prepreg sheet having an angle of -α ゜ is used only in the same layer. , One + α layer with one −
Uniformity is achieved by using the α layer so that the torsional stiffness is substantially the same in both clockwise and counterclockwise directions.

[0008]

However, as long as the method of sequentially laminating the prepreg sheets from the inner periphery to the outer periphery is employed, one of the + α layer and the −α layer is on the inner periphery and the other is on the outer periphery. And the second moment of area of the bias layer wound on the outer peripheral side is larger. As a result, there is a problem that it is difficult to obtain sufficient uniformity. Also, due to the non-uniformity of the bias layer, when a highly elastic reinforcing fiber is used for the bias layer, the shaft is likely to warp to one side, making it difficult to satisfy the requirement that the shaft must be straight.

The present invention has been made in view of the above problems, and has as its object to improve the arrangement of the bias layers to make the torsional rigidity around the left and right uniform.

[0010] In order to solve the above problems, the present invention provides a golf club shaft comprising a tubular body formed by laminating fiber reinforced prepreg sheets obtained by impregnating a synthetic resin into reinforced fibers. Of these, two bias layers, two + α layers, and two −α layers are provided, in which the angle α of the reinforcing fiber with respect to the axis of the tubular body is inclined in the range of α = ± 30 ° to ± 60 °. Golf characterized by being arranged in the order of + α layer, −α layer, −α layer, + α layer, or −α layer, + α layer, + α layer, −α layer from the peripheral side to the outer peripheral side. Offers club shafts.

That is, the two + α layers are inclined at the same angle in the above angle range, and the two −α layers are inclined at the same angle by inverting the + α layer and + −. As described above, the bias layers of + α and the bias layers of −α are formed of the same number of two layers, and in the relation of the inner and outer layers, the stacked arrangement is mirror-symmetric with one of the other being interposed between the other. For example, the total value of the second moment of area of the one inner layer + α layer and the one outer layer of + α layer and the total value of the second moment of area of the two −α layers of the intermediate layer therebetween are calculated as follows. They can be the same or substantially the same. Therefore, the uniformity of the counterclockwise torsional rigidity and the counterclockwise torsional rigidity can be improved.

When the number of prepreg sheets stacked increases, the weight of the golf club shaft increases.
Although the above four bias layers are preferable, for example, four + α layers and four −α layers may be provided and arranged in a mirror-symmetric manner as described above.

Each of the bias layers has a size such that no gap is formed at the seam in the circumferential direction, and the volume of the bias layer increases from the inner layer to the outer layer to be laminated. The sum of the volume of the + α layer and the −α of the two layers
The total volume of the layers is set to be equal.

Since the thickness of the prepreg sheet is constant, the total value of the areas of the two + α layers and the total value of the areas of the −α layers may be made equal. The thickness of the bias layer is 0.05 mm to 0.25
mm, the total volume of the + α layer and the total volume of the −α layer may be set to be equal to each other as described above.

The seams of the plurality of bias layers are displaced in the circumferential direction so that they do not coincide in the circumferential direction. For example, when two + α layers and two −α layers are used, the seam between the two + α layers is 180 ° out of phase with each other, while the seam between the two −α layers is 180 ° from each other.
゜ The phase is set to 90 degrees with the + α layer. Alternatively, the joints are sequentially phased by 90 degrees from the inner peripheral side. In this way, if the seam of the strip-shaped bias layer wound around the mandrel is devised, the bending rigidity in the circumferential direction can be made more uniform.

In the shaft of the present invention, as in the conventional case, a straight parallel to the axis of the shaft is arranged on the outermost side of the shaft to increase the bending rigidity of the shaft.

A hoop layer and a straight layer may be interposed between the bias layers or on the inner peripheral side. That is, if the + α layer and the −α layer of the bias layer are arranged mirror-symmetrically, and the second moment of area of the + α layer and the second moment of area of the −α layer are set to be substantially the same, the required A straight layer and / or a hoop layer can be interposed at the position.

[0018]

Embodiments of the present invention will be described below. The shaft 10 made of a tubular body according to the embodiment of the present invention shown in FIG. 1 includes a first + bias layer 11, a first −bias layer 12, a second −bias layer 13, and a Two + bias layers 14 and two straight layers 15 and 16 are sequentially arranged, and a straight layer 17 is further arranged on the outer periphery of the straight layer 16 on the small diameter side on the head connection side. The shaft 10 of the present embodiment has a length L of 1143 mm, an inner diameter of the hollow portion (that is, an outer diameter of the mandrel is 5.6 mm on the smaller diameter side of the head connection side),
It is 13.0 mm on the large diameter side on the grip side.

As each of the layers 11 to 17, a carbon fiber prepreg sheet (8055S-12 manufactured by Toray Industries, Inc.) is used. The tensile modulus of the prepreg sheet is 30,000 k
g, tensile strength is 560 kg. The above + bias layer 1
1 and 14, the reinforcing fibers have the same angle α in the range of α = + 30 ° to 60 ° with respect to the axis L of the shaft 10. In the present embodiment, the positive bias layers 11, 1
4 is + 45 °. Above-bias layer 1
Nos. 2 and 13 indicate that the reinforcing fiber has the same angle α with respect to the axis L of the shaft 10 in the range of α = −30 ° to 60 °, and the + bias layers 11, 14 and + − are reversed. In this embodiment, the angle is set to -45 °.

Further, each of the above prepreg sheets 11 to 16
Is a length L (1143 mm in this embodiment) corresponding to the length of the shaft 10, as shown in FIGS.
The width is cut out into a strip having a small width W1 on the head side and a large width W2 on the grip side. As described above, by being formed in a strip shape, it is possible to form a tapered tubular body having a small diameter at one end in the axial direction and a large diameter at the other end in a state wound around the mandrel.

In the first embodiment shown in FIG. 2, all the biases 11 to 14 have the same shape, W1 is 19.5 mm, and W2 is 47.
mm. In the second embodiment shown in FIG.
Reference numeral 14 denotes a first + bias 11 which has a larger area in order from the bias 11 wound around the inner periphery toward the outer periphery.
Are W1: 18 mm, W2: 44 mm, the first -bias layer 12 is W1: 19 mm, W2: 46 mm, and the second -bias 13 is W1: 20 mm, W2: 48 mm.
And the second + bias layer 14 is W1: 21 mm, W
2: 50 mm.

The straight layer 15 has W1: 44 mm and W2: 98 mm in both the first and second embodiments, and the straight layer 16 has W1: 46 mm and W2: 101 mm. The outermost straight layer 17 wound around the head
Has a length L ′ of 230 mm, W1: 140 mm, and W2:
It has a triangular shape of 0 mm.

FIG. 4 shows a comparison with the first and second embodiments.
The shaft of the comparative example made of the prepreg sheet shown in FIG. In this comparative example, two bias layers 20 and 21 are provided. The bias layer 20 serving as the inner layer is formed by adding the reinforcing fiber to +
45 °, and the outer bias layer 21 has a reinforcing fiber of −45.
゜The bias layers 20 and 21 have the same shape, and have a width W1: 39 mm and W2: 94 mm. In the shaft of the comparative example, the bias layers 20, 21 and the straight layers 15, 16, 17 are sequentially laminated from the inner layer side to the outer layer. And

The above Examples 1 and 2 and Comparative Example are all manufactured by the same manufacturing method. That is, the smaller diameter side is 5.6m
The prepreg sheet is wound sequentially from the inner layer side around a mandrel made of a single tapered iron core having a diameter of 13.0 mm and a large diameter of 13.0 mm. After laminating and winding a prepreg sheet, a wrapping tape is wound, and after heat curing, the mandrel is pulled out, the wrapping tape on the surface is peeled off, and the surface is polished to form a golf club shaft.

In both the first and second embodiments and the comparative example, the joints (that is, seams) at both ends of each of the bias layers 11 to 14 are not located at the same position, but are dispersed in the circumferential direction and the phase is sequentially shifted by 90 degrees from the inner circumferential side. Let me.

For Examples 1 and 2 and Comparative Example, comparative tests were conducted for torsional rigidity, bending rigidity and warpage. In each of Examples 1 and 2 and Comparative Example, five tests were performed, and the average value was determined. The test results are shown in Table 1 below.

The torsional rigidity is 50 from the small diameter end of the shaft.
mm was fixed, a torsion moment of 1 lb-ft was applied to a position P1 825 mm away from the large diameter side, and the rotation angle (skew angle) of the position P1 at that time was measured.

The bending rigidity is 190 from the large diameter side of the shaft.
mm was fixed, and a 2.7 kg load was applied to a portion P2 at a position 820 mm away from the small diameter side, and the amount of deflection at that position P2 was measured.

The warpage was measured at a point 200 mm from the large diameter side and 70 mm.
With two points of 0 mm supported, the difference between the highest point and the lowest point at 10 mm from the tip on the smaller diameter side when the shaft was rotated was measured.

[0030]

[Table 1]

The test results of the torsional stiffness are the same in Example 2 with the same torsion angle (6.0 °) in the clockwise and counterclockwise directions.
In Example 1, the difference between the clockwise direction and the counterclockwise direction was 0.1 °, which was almost the same. On the other hand, in the comparative example, the difference between the clockwise direction and the counterclockwise direction was 0.3 °, which was larger than that in Examples 1 and 2. From this test result, it was confirmed that in this example, the torsional rigidity in the left-right rotation direction was substantially the same, and the torsional rigidity was excellent in uniformity.

The test result of the bending stiffness shows that the difference between the maximum value and the minimum value of the amount of deflection is 1.1 mm in Example 2 and the minimum,
Example 1 was also smaller than the comparative example, and it was confirmed that the bending rigidity of this example was superior to that of the comparative example.

The results of the warp test are as follows:
Although it was 4 mm or less, the comparative example was 2.7 mm, and it was confirmed that the example was less warped than the comparative example.

[0034]

As is apparent from the above description, in the golf club shaft of the present invention, a plurality of bias layers having the same number of the bias layers and the negative layer having the reinforcing fiber angles of + and − are arranged, respectively. Since the bias layer is arranged so that the total of the moment of inertia of the bias layer and the total of the moment of inertia of the-side bias layer substantially coincide, the clockwise torsional rigidity and the counterclockwise torsional rigidity are substantially the same. As a result, the uniformity regarding the torsional rigidity of the golf club shaft can be improved.

Further, since the angle of the reinforcing fibers of the bias layer is made uniform between the + side and the-side, even if a highly elastic reinforcing fiber is used for the bias layer, the shaft is prevented from warping in a specific direction. it can.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing an embodiment of the present invention.

FIG. 2 is a development view of a prepreg sheet used in Example 1 of the present invention.

FIG. 3 is a development view of a prepreg sheet used in Embodiment 2 of the present invention.

FIG. 4 is a development view of a prepreg sheet used in a comparative example.

FIG. 5 is a view showing a prepreg sheet forming a golf club shaft.

FIG. 6 is a partial perspective view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Golf club shaft 11 1st + bias layer 12 1st -bias layer 13 2nd -bias layer 14 2nd + bias layer

Claims (2)

[Claims] 1. A golf club shaft comprising a tubular body formed by laminating a fiber reinforced prepreg sheet obtained by impregnating a synthetic resin into a reinforcing fiber, wherein a shaft of the tubular body in the laminated fiber reinforced prepreg sheet is provided. The angle α of the reinforcing fiber to the heart is α = ± 30 ° to ± 6
A bias layer inclined in the range of 0 °, two + α layers, −
Two α layers are provided, and from the inner peripheral side to the outer peripheral side, a + α layer,
-Α layer, -α layer, + α layer in order, or -α layer, + α
A golf club shaft, comprising: a layer, a + α layer, and a −α layer. 2. Each of the bias layers has a size such that no gap is formed at a seam in the circumferential direction, and the volume of the bias layer increases from the inner layer to the outer layer to be laminated. The total volume of the plurality of + α layers and the total volume of the −α layers are set to be equal.
2. The golf club shaft according to 1.