JP2003000779A - Golf club shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf club shaft comprising a fiber reinforced resin layer whose weight is 65 g or less which contains a carbon fiber reinforced layer of at a tip part at a head mounting side, wherein the impact strength of the tip part can be improved without thickning the reinforced layer. SOLUTION: A carbon fiber orientation angle of the reinforced layer is 10 to 30 degrees to a shaft axis. When the tensile elastic modulas of a carbon fiber of the reinforced layer is 196 to 343 GPa. The impact strength of a tip portion can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft of a golf club which has a large impact strength at its tip end portion on the head mounting side despite being lightweight.

[0002]

BACKGROUND OF THE INVENTION Like the first and second shots of a golf play,
When the player swings the golf club to the full and causes the golf ball to fly far, an impact force of 1 ton or more is usually applied to the head. Therefore, the tip portion of the shaft on which the head is mounted receives this impact force. It must withstand and support the head. Especially when hitting a golf ball at a portion of the head that is out of the swath spot,
Since the stress and strain due to the impact force of the head are further concentrated on the tip portion of the shaft, the strength of the tip portion of the shaft must be increased.

Therefore, the tip of the shaft of the golf club is provided with a means for increasing the strength as compared with the prior art.
For example, a reinforcing fiber such as carbon fiber, glass fiber, aramid fiber, or boron fiber is mixed with a resin, and a fiber-reinforced prepreg sheet having enhanced strength is laminated by winding a plurality of mandrels by a sheet winding method. After that, in the case of the non-metal shaft 1 which is a laminated body by heat-curing treatment and fusing fiber-reinforced prepreg sheets to each other, as shown in FIG. 3, the tip portion 2 is reinforced with fiber-reinforced resin. Around the layer 3.

FIG. 4 shows an example of a method of surrounding the reinforcing layer. The mandrel 4 has a first main prepreg sheet 5 and a second main prepreg sheet 6 sequentially over the entire length of the mandrel 4.
After forming the inner layer 7 by winding more than one turn, the intermediate prepreg sheet 8 having a shorter length is wound toward the tip side and partially wound for one or more turns to form the intermediate layer 9 on the outer circumference of the inner layer 7. Then, on the outer periphery of the mid layer 9, a third main prepreg-
The outer layer 13 is formed by sequentially winding the belt 10, the fourth main prepreg sheet 11, and the fifth main prepreg sheet 12 one or more turns over the entire length. Finally, the tip side reinforcing prepreg sheet 14 is wrapped around only the tip portion of the mandrel 4 on the outer periphery of the fifth main prepreg sheet 12 to form the reinforcing layer 3 which is then heat-cured, and the mandrel 4 is pulled out. Here, the first main prepreg sheet 5 and the second main prepreg sheet 6 are usually wound so that the reinforcing fiber directions are inclined in different directions with respect to the axial direction of the mandrel 4 to prevent the shaft from twisting. There is. Further, the intermediate prepreg sheet 8, the third to fifth main prepreg sheets 10 to 12 to be wound thereafter, the tip side reinforcing prepreg sheet 14 and the like are wound so that the reinforcing fibers are parallel to the axial direction of the mandrel 4, The bending strength is increased and delamination between the prepreg sheets is prevented. In FIG. 4, lines that are parallel or oblique to the longitudinal direction of the prepreg sheet are schematic representations of reinforcing fibers. Weight so far is 70
It was general to use a carbon fiber reinforced prepreg sheet having a tensile elastic modulus of 230 GPa, which is generally most commonly used for shafts of g or more.

However, the shaft of a golf club is required to be lighter in weight in recent years due to the design requirements of the golf club, and the weight of the shaft has been reduced to 65 g or less. To reduce the weight of the shaft, the tensile elastic modulus is 2
High elasticity carbon fiber reinforced prepreg sheet of 94 GPa or more can be used to reduce the thickness while maintaining rigidity and bending strength. However, when the thickness is reduced, the impact strength of the entire shaft also decreases. I will end up. Therefore, when the shaft is made thin, the impact strength of the tip portion where the head impact force when hitting a golf ball is concentrated is inferior to the conventional one, and the impact resistance must be increased.

In order to increase the impact strength of the tip portion of the shaft, it is sufficient to increase the winding amount of the reinforcing layer 3 to make it thicker, but the fiber orientation direction of the prepreg sheet 14 for reinforcing the tip side is the axis of the shaft. If they are parallel, the reinforcing layer 3 has to be wound more than before, and the wall thickness of the reinforcing layer 3 becomes thicker than before, so that the reinforcing layer 3 cannot be inserted into the hole of the head during assembly. Further, if the reinforcing layer 3 is thick, the weight of the tip end side increases although the shaft is made lighter. In addition, the center of gravity of the shaft moves toward the tip end, impairing the performance of the lightweight shaft.

[0007]

SUMMARY OF THE INVENTION The present invention is a golf club shaft comprising a laminate of fiber reinforced resin layers, the shaft having a weight of 65 g or less, and a carbon fiber reinforced resin reinforced at the tip end portion on the head mounting side. Provided is a golf club shaft in which the impact strength of the tip portion of the shaft can be increased even when the reinforcing layer is not so thick in the layered structure.

[0008]

According to the present invention, the carbon fiber orientation angle of the reinforcing layer is set to 10 to 30 degrees with respect to the shaft axis. Here, the carbon fiber of the reinforcing layer has a tensile elastic modulus of 19
It is preferably 6 to 343 GPa.

The inventors of the present invention have studied various methods of increasing the impact strength of the shaft tip without increasing the winding amount of the prepreg sheet. As a result, the carbon fiber orientation angle of the reinforcing layer with respect to the shaft axis is inclined by 10 to 30 degrees. I found what I should do. There is known a method of preventing the shaft from twisting when hitting a golf ball by setting the carbon fiber orientation angle of the reinforcing layer with respect to the shaft axis to 35 to 55 degrees (JP-A-2001-46565). With such a large orientation angle, the impact strength at the tip of the shaft cannot be increased.
In the present invention, the carbon fiber orientation angle with respect to the shaft axis is 10
Even if it is smaller than 30 degrees or larger than 30 degrees, the impact strength of the tip portion of the shaft is insufficient, so that the amount of winding of the prepreg sheet must be increased. As a result, the weight of the tip portion of the shaft increases, the center of gravity of the shaft moves toward the tip side, and the performance of the lightweight shaft is impaired. Further, if it is larger than 30 degrees, the prepreg sheet of the reinforcing layer may be peeled off in the polishing step during manufacturing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The reinforcing layer is usually formed as the outermost layer as shown in FIG. 1, but it may be formed inside as shown in FIG. The prepreg sheet of the reinforcing layer preferably has a carbon fiber tensile elastic modulus of 196 to 343 GPa. If the tensile elastic modulus is less than 196 GPa, the rigidity of the tip portion of the shaft cannot be obtained, and if it exceeds 343 GPa, the impact strength is poor. When two or more prepreg sheets are wound to form the reinforcing layer, the carbon fiber orientation direction of the reinforcing layer may be opposite to the shaft axis, and the winding start position may be 180 degrees in the circumferential direction. You may shift it. Reinforcement layer 1 from the shaft tip to the center side
If it is formed to a length of 00 to 400 mm, the impact strength of the tip part can be improved.

[0011]

[Examples] Examples 1 to 3 Using a carbon fiber reinforced prepreg sheet, the outer diameter was tapered from the base toward the tip, and the base diameter was 15.
Various unpainted golf club shafts having a diameter of 0 mm, a tip diameter of 8.5 mm and a length of 1145 mm were manufactured. The carbon fiber reinforced prepreg sheet is laminated as shown in FIG.
As the main prepreg sheet 5 and the second main prepreg sheet 6, those having a trade name of P8055S-10 are used, and the orientation angle of the carbon fiber with respect to the shaft axis is +45 degrees,
Six plies were wound around the mandrel 4 after they were bonded to each other so that the winding phase became 45 degrees and the winding phase at the time of winding around the mandrel 4 was shifted by 180 degrees. In addition, the intermediate prepreg sheet 8 has a product name of P3052S-12,
5 Main prepreg sheets 10 to 12 are trade name P2053
Each of -15 was used, and the carbon fibers were wound so as to be parallel to the shaft axis. further,
Product name P805 for the tip side reinforcement prepreg sheet 14
3S-07, the orientation angle of the carbon fiber with respect to the shaft axis was +10 in Example 1.
Those bonded to each other at +10 degrees and -10 degrees, those bonded to each other at +20 degrees and -20 degrees in Example 2, and those bonded to each other at +30 degrees and -30 degrees in Example 3 Was wrapped around the tip of the shaft.

Examples 4 to 6 In Examples 1 to 3, the trade name P3051S-07 was used in place of the trade name P8053S-07 used for the tip side reinforcing prepreg sheet 14, and this was preliminarily used in Example 4. Orientation angle of carbon fiber with respect to shaft axis is +
What was stuck to 10 degrees and -10 degrees was stuck to be +20 degrees and -20 degrees in Example 5, and was stuck to be +30 degrees and -30 degrees in Example 6. Each one was wrapped around the tip of the shaft.

Example 7 In Examples 1 to 3, the product name P6052-07 was used in place of the product name P8053S-07 used for the tip side reinforcing prepreg sheet 14, and this was previously prepared from carbon fiber with respect to the shaft axis. Orientation angle is +20 degrees and -2
Three plies were wound around the tip of the shaft so that they were laminated at 0 degree.

Example 8 Tip-side reinforcing prepreg sheet 1 in Examples 1 to 3
4 was wound after winding the intermediate prepreg sheet 8 and before winding the third main prepreg sheet 10. Then, the winding of the tip side reinforcing prepreg sheet 14 was the same as in Example 2.

[0015]

[Comparative Example] Comparative Example 1 In Examples 1 to 3, trade name P8055S used for the first main prepreg sheet 5 and the second main prepreg sheet 6.
The trade name P8055S-15 was used instead of -10.
Also, instead of the product name P8053S-07 used for the tip side reinforcing prepreg sheet 14, the product name P3053S.
Using -15, the carbon fiber was wound so as to be parallel to the shaft axis.

Comparative Example 2 In Comparative Example 1, the trade name P8055S-1 used for the first main prepreg sheet 5 and the second main prepreg sheet 6 was used.
The product name P8055S-10 was used in place of 5.

Comparative Example 3 In Comparative Example 1, the front end side reinforcing prepreg sheet 14 was used.
The product name P3051S-07 was used in place of the product name P3053S-15 used in 1., the two carbon fibers were laminated so as to be parallel, and then the carbon fibers were wound so as to be parallel to the shaft axis.

Comparative Example 4 In Comparative Example 1, the tip side reinforcing prepreg sheet 14 was used.
The product name P8053S-15 was used instead of the product name P3053S-15 used in 1., and two carbon fibers were laminated so as to be parallel to each other, and then the carbon fibers were wound so as to be parallel to the shaft axis line.

Comparative Example 5 In Examples 1 to 3, the prepreg sheet 14 for reinforcing the tip side was laminated at +40 degrees and -40 degrees, and was wound around the tip portion of the shaft.

Comparative Example 6 In Examples 4 to 6, the tip side reinforcing prepreg sheets 14 bonded to each other at +40 degrees and −40 degrees were wound around the tip portion of the shaft.

Table 1 shows the physical properties of the prepreg sheet used for manufacturing the above shaft. Table 2 shows the results of the shaft Izod impact test and the bending strength test. In addition,
Both tests were carried out as follows. (1) Izod impact test Using a U-F IMPACT TESTER manufactured by Ueshima Seisakusho, the weight of the falling weight is 5.881 kg, and the weight of the falling weight at the time of collision is 3.
It was carried out under the condition of 46 m / sec. The larger the impact fracture energy value (J) at the tip of the shaft, the higher the impact resistance performance. If it is about 14 J or more, the impact strength at the tip of the shaft is at a level without problems. (2) Bending strength test The bending strength test was conducted in accordance with "Certification Criteria for Golf Club Shafts and Criteria Confirmation Method" of the Product Safety Association. That is, the shaft is placed on two fulcrums with a distance of 150 mm, the position is adjusted so that the position (point T) 90 mm from the tip of the shaft is the center between both fulcrums, and then 90 mm from the tip.
A load was applied to the position of 3 to perform a 3-point bending strength test. The product safety association certification standard for this test is 800 N or more.

[0022]

[Table 1]

[0023]

[Table 2] (Note) The reinforcing fiber orientation angle is with respect to the shaft axis.

As shown in Table 2, the shaft has a weight of 69.
When g is (Comparative Example 1), even if the fibers of the reinforcing layer are parallel to the shaft axis, the Izod impact strength is as large as 14.0 J, but when the weight is as light as 55 g, the fibers of the reinforcing layer become the shaft axis. In parallel, it decreases to 12.1J to 13.9J (Comparative Examples 2 to 4) and does not become larger than 14.0J.

However, the fiber orientation angle of the reinforcing layer should be ±
When it is 10 degrees or more, the Izod impact strength suddenly increases, and a high Izod impact strength is exhibited at ± 10 degrees to ± 30 degrees. However, at ± 40 degrees, the Izod impact strength will decrease. Even if the fiber orientation angle of the reinforcing layer is ± 20 degrees, if the fiber tensile elastic modulus is as high as 436 MPa, the Izod impact strength will decrease to 9.3 J. As shown in Example 8, even when the reinforcing layer is on the inner layer side, the Izod impact strength is considerably high at 17.2 J, and the effect of the fiber orientation angle of the reinforcing layer appears.

If the fiber orientation of the reinforcing layer is not parallel to the axis of the shaft, the bending strength will decrease, but since it is 800 N or more, there is no problem as a shaft.

[0027]

INDUSTRIAL APPLICABILITY As described above, a golf club shaft made of a laminate of fiber reinforced resin layers has a weight of 65.
In the case where a reinforcing layer of carbon fiber reinforced resin is circumferentially provided at the tip portion on the head mounting side of g or less, the carbon fiber orientation angle of the reinforcing layer is 10 to 3 with respect to the shaft axis.
When it is set to 0 degrees, the impact strength of the tip portion can be increased without making the reinforcing layer portion have an outer diameter that cannot be inserted into the head and without making the weight such that the center of gravity moves to the tip side. Further, the tensile elastic modulus of the carbon fiber of the reinforcing layer is 1
When it is 96 to 343 GPa, the impact strength of the tip portion can be increased.

[Brief description of drawings]

FIG. 1 is a plan view of a fiber-reinforced prepreg sheet and a stacking order thereof when manufacturing a shaft of a golf club of the present invention.

FIG. 2 is a plan view of a fiber-reinforced prepreg sheet and a stacking order thereof when manufacturing a shaft of another golf club of the present invention.

FIG. 3 is a vertical cross-sectional view of a tip portion of a non-metallic shaft of a conventional golf club.

FIG. 4 is a plan view of a fiber-reinforced prepreg sheet and a stacking order thereof when manufacturing a shaft of a conventional golf club.

[Explanation of symbols]

1 Non-metal shaft 2 Tip 3 Reinforcing layer 4 Mandrel 5 1st main prepreg sheet 6 Second main prepreg sheet 7 Inner layer 8 Intermediate prepreg sheet 9 Middle class 10 Third Main Prepreg Sheet 11 4th main prepreg sheet 12 Fifth main prepreg sheet 13 outer layer 14 Tip side reinforcement prepreg sheet

Claims (2)

[Claims] 1. A shaft of a golf club comprising a laminate of fiber reinforced resin layers, the weight of which is 65 g or less, and a carbon fiber reinforced resin reinforcement layer is circumferentially provided around a head mounting side tip portion. 2. The shaft of a golf club, wherein the carbon fiber orientation angle of the reinforcing layer is 10 to 30 degrees with respect to the shaft axis. 2. The tensile elastic modulus of the carbon fiber of the reinforcing layer is 19
The golf club shaft according to claim 1, wherein the shaft is 6 to 343 GPa.