KR20130135080A - Golf club steel shaft - Google Patents

Abstract

Disclosed is a steel shaft for a gold club having: 51.0<=Y<=60.0 of the centroidal ratio Y (%), which is LG/LS; 80<=X<=140 of shaft weight X (g); and 30<=LS<=42 of the full length of the shaft, which is LS (inch), wherein LG refers to a distance from the front end of the shaft to the centroid of the shaft and LS refers to the full length of the shaft.

Description

Golf club steel shaft {GOLF CLUB STEEL SHAFT}

The present invention relates to a steel shaft.

For golfers, the distance of the ball is one of the important factors when selecting a golf club. Accordingly, in order to increase the distance of the ball, conventionally, various improvements have been made on the material and the shape of the elements constituting the golf club.

However, in recent years, in order to suppress excessive distance and improve the fairness of the game, the repulsive performance of the face, the club length and the moment of inertia of the head are regulated by rules, and it is difficult to improve the distance.

Under such circumstances, it has been proposed to increase the head speed of the club by lengthening the club length to the upper limit regulated by the rule, taking into consideration that the first speed of the ball greatly affects the flying distance (see, for example, Patent Document 1 ).

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-201911

However, in the method of increasing the club head speed by lengthening the club length, as the length of the club becomes longer, the controllability of the head is lowered, and it becomes difficult to hit the ball with the sweet spot of the head. As a result, the meet ratio of the ball is deteriorated and the initial velocity of the ball can not be stably increased. As a result, the distance of the ball can not be improved.

In order to solve this problem, it is necessary to reduce the club length to increase the rate of feed, and to increase the head weight to speed up the ball speed. However, if the head weight is simply increased, the club inertia moment becomes large, There is a problem that the ease of swing of the club is deteriorated.

Therefore, it is conceivable to move the center of gravity of the shaft to the butt side (hand side) in order to prevent the increase in the moment of inertia of the club without increasing the club weight.

Although the movement of the center of gravity of the shaft to the butt side can be achieved by increasing the thickness of the butt side portion of the shaft in general, the bending rigidity EI (kgf · m2) of the butt side portion of the shaft also increases So that the feel of the ball when hit and the directionality of the ball are lowered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a golf shaft for a golf club which can extend the distance of the ball while maintaining the directionality of the padding and the ball when the ball is hit.

(1) a steel shaft for a golf club of the present invention, when a the distance of the shaft center of gravity from the shaft distal end a full-length (全長) to L _G, and a shaft with L _S, L _G / L _S of the center of gravity ratio Y (%) is 51.0? Y? 60.0,

Wherein the shaft weight X (g) is 80? X? 140 and the shaft total length L _S (inch) is 30? L _S? 42.

In the steel shaft for a golf club of the present invention, since the center of gravity Y (%), the shaft weight X (g) and the shaft total length L _S (inches) It is possible to extend the distance of the ball while maintaining the directionality of the ball and the filling of the ball.

(2) In the steel shaft for a golf club of the above (1), the thickness of the portion from the butt end to the shaft tip side of 150 mm is preferably 0.30 mm or more and 0.40 mm or less.

(3) In the golf shaft for a golf club of (1) or (2), it is preferable that an outer diameter of a portion from the butt end to the shaft tip side of 150 mm is 14.5 mm or more and 15.3 mm or less.

(4) In the steel shaft for a golf club of the above (1) or (2), it is preferable that the number of steps of the portion from the butt end to the shaft tip side of 400 mm is 5 or more and 8 or less.

According to the steel shaft of the present invention, it is possible to extend the distance of the ball while maintaining the directionality of the padding or the ball when the ball is hit.

1 is an explanatory view of a golf club including an embodiment of a steel shaft for a golf club of the present invention.
Fig. 2 is a view for explaining a method of measuring the T point intensity. Fig.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a golf shaft for a golf club according to the present invention will be described in detail with reference to the accompanying drawings.

1 is an explanatory diagram showing the entire golf club 1 including a steel shaft for a golf club (hereinafter, simply referred to as a &quot; shaft &quot;) according to an embodiment of the present invention. The golf club 1 has an iron type golf club head 2 having a predetermined loft angle, a shaft 3, and a grip 4. The head 2 has a hosel 6 having a shaft hole 5 for inserting and fixing the tip end 3a of the shaft 3 at the tip side. The butt end 3b on the rear end side of the shaft 3 is inserted and fixed in the grip hole 7 of the grip 4. [ The tip end 3a is located inside the head 2 and the butt end 3b is located inside the grip 4. [ In Fig. 1, what is indicated by the symbol G is the center of gravity of the shaft 3 (center of gravity). The center of gravity G is located on the axis of the shaft 3 in the shaft 3.

The weight of the golf club 1 is not particularly limited in the present invention, but is preferably set within a range of 360 g or more. If the weight of the golf club 1 is too light, the strength of each element (part) constituting the golf club 1 becomes low, and the durability may be deteriorated. Therefore, the weight of the golf club 1 is preferably 370 g or more, more preferably 380 g or more. On the other hand, if the weight of the golf club 1 is too heavy, swing becomes difficult and it becomes difficult to raise the head speed. Therefore, the weight of the golf club 1 is more preferably 500 g or less, particularly preferably 490 g or less.

The length of the golf club 1 itself is not particularly limited in the present invention, but is usually 34.0 to 42.0 inches. If the length of the golf club 1 is too short, the ease of swing is good, but the turning radius of the swing becomes small, making it difficult to obtain a sufficient head speed. Therefore, the ball speed can not be increased, and the distance of the ball can not be extended. Therefore, the length of the golf club 1 is preferably 34.5 inches or more, more preferably 35.0 inches or more. On the other hand, if the length of the golf club 1 is too long, it becomes difficult to swing the club, so that the head speed is lowered. Therefore, the ball speed can not be increased, and the distance of the ball can not be extended. Therefore, the length of the golf club 1 is preferably 41.5 inches or less, more preferably 41.0 inches or less.

In this specification, the term "club length" refers to the length of the "1c length" in the "one club" of the golf rules "Design of an attached rule II club" set by the R & A (Royal and Ancient Golf Club of Saint Andrews) Is a length measured based on a substrate.

[Configuration of head]

The head 2 in the present embodiment is a solid iron head and has large moment of inertia. In a club having a large inertia moment of the head 2, the effect of improving the distance can be stably obtained.

The material of the head 2 is not particularly limited in the present invention. For example, titanium, titanium alloy, stainless steel, maraging steel, soft iron and the like can be used. Further, instead of manufacturing using a single material, the head 2 may be manufactured by appropriately combining a plurality of materials.

In the present invention, the weight of the head 2 alone is not particularly limited, but is preferably in the range of 230 g to 310 g. If the head 2 is too light, kinetic energy of the head 2 can not be sufficiently applied to the ball, making it difficult to increase the ball speed. Therefore, the head is more preferably 235 g or more, particularly preferably 240 g or more. On the other hand, if the weight of the head 2 is too large, the golf club 1 becomes heavy, making it difficult to swing. Accordingly, it is more preferably 305 g or less, particularly preferably 300 g or less.

In the golf club 1 of the present embodiment, the ratio of the head weight to the club weight (head weight / club weight) is set to 0.55 or more and 0.70 or less. If the ratio is too small, the kinetic energy of the head 2 becomes small, and it becomes difficult to obtain a sufficient ball speed. Therefore, the ratio is preferably 0.56 or more, more preferably 0.57 or more. On the other hand, if the ratio is too large, the head 2 becomes heavy, making it difficult to swing the club. Therefore, the ratio is preferably 0.69 or less, more preferably 0.68 or less.

[Configuration of grip]

In the present invention, the material and the structure of the grip 4 are not particularly limited, and a commonly used one can be suitably employed. For example, those obtained by kneading and kneading a kneaded material obtained by blending oil, carbon black, sulfur and zinc oxide with a natural rubber into a predetermined shape and curing the mixture may be used.

In the present invention, the weight of the grip 4 itself is not particularly limited, but it can be generally set to 20 g or more and 55 g or less. If the weight of the grip 4 is too light, the strength of the grip 4 is lowered, and the durability of the grip 4 may be lowered. Therefore, the weight of the grip 4 is preferably 23 g or more, more preferably 26 g or more. On the other hand, if the weight of the grip 4 is too heavy, the golf club 1 becomes heavy, making swing difficult. Therefore, the weight of the grip 4 is preferably 53 g or less, more preferably 51 g or less.

[Configuration of shaft]

The shaft 3 in this embodiment is a steel shaft having a hollow structure, which is manufactured by an ordinary method. The overall length of the shaft 3 is L _S and the distance from the tip end 3a of the shaft 3 to the center of gravity G of the shaft 3 is L _G.

The weight X of the shaft 3 in the present invention is set to 80 g or more and 140 g or less. If the weight of the shaft 3 is too light, the possibility that the strength such as the bending strength becomes insufficient increases because the thickness is thin. Therefore, the weight is preferably 85 g or more, more preferably 90 g or more. On the other hand, if the weight of the shaft 3 exceeds 140 g, the entire golf club 1 becomes heavy, making it difficult to swing quickly. Therefore, the weight of the shaft 3 is preferably 135 g or less, more preferably 130 g or less.

The length (total length) L _S of the shaft 3 is set to 30 inches or more and 42 inches or less. If the length of the shaft 3 is too short, the turning radius of the swing becomes small, and it becomes difficult to obtain a sufficient head speed. Because of this, the ball speed can not be increased quickly, and the distance of the ball can not be extended. Therefore, the length of the shaft 3 is preferably 32 inches or more, and more preferably 34 inches or more. On the other hand, if the length of the shaft 3 is too long, the moment of inertia at the grip end becomes large, and a golfer having no force is pushed. Therefore, the head speed can not be increased, and the flying distance of the ball can not be extended. Therefore, the length of the shaft 3 is preferably 41.5 inches or less, and more preferably 41 inches or less.

The center of gravity of the shaft 3 itself is not particularly limited in the present invention but is generally in the range of 595 mm to 505 mm from the tip end 3a of the shaft 3 Mm. If the position of the center of gravity G of the shaft 3 is less than 505 mm from the tip of the shaft 3, it can not be said that the position of the center of gravity has moved sufficiently in the hand side direction, It is highly likely that it will not lead to speed up. Therefore, the center of gravity of the shaft 3 is preferably 510 mm or more from the tip of the shaft 3, and more preferably 515 mm or more. On the other hand, if the position of the center of gravity G of the shaft 3 exceeds 595 mm from the tip of the shaft 3, the thickness at the tip of the shaft becomes thin, and the strength such as the bending strength is likely to become insufficient. Therefore, the center-of-gravity position of the shaft 3 is preferably 585 mm or less from the tip of the shaft 3, and more preferably 575 mm or less.

When the full-length of the shaft 3, the distance from the shaft center of gravity G from the front end to the L _G, and the shaft 3 of the invention with L _S, L _G / L _S of the center of gravity ratio Y (%) Is 51.0? Y? 60.0.

When the center-of-gravity ratio Y is less than 51.0 (%), the center of gravity of the shaft approaches the tip of the shaft. Therefore, in order to achieve the swing balance of the conventional level, The degree of freedom of the display device becomes small. That is, it is impossible to introduce a technique of reducing the moment of inertia of the head and lowering the center of gravity. Therefore, it is difficult to achieve a long distance of the ball. Therefore, the center of gravity Y is preferably 52.0 or more, more preferably 53.0 or more.

On the other hand, if the center-of-gravity ratio Y exceeds 60.0 (%), the center of gravity of the shaft becomes excessively close to the rear end side of the shaft. This excessively increases the weight of the head, That is, even if the swing balance becomes the same as the conventional one, the swing becomes difficult. Further, since the weight is disposed at the rear end side of the shaft than at the front end thereof, the strength at the tip end side of the shaft is weakened. Therefore, the center of gravity Y is preferably 58.0 or less, and more preferably 56.0 or less.

In the present embodiment, the thickness t of the part from the butt end 3b of the shaft 3 to the tip of the shaft to 150 mm is 0.30 mm or more and 0.40 mm or less.

When the thickness t is less than 0.3 mm, the center of gravity of the shaft is close to the tip of the shaft. Therefore, in order to achieve the swing balance of the conventional level, the weight of the head must be reduced, . That is, it is impossible to introduce a technique of reducing the moment of inertia of the head and lowering the center of gravity. Therefore, it is difficult to achieve a long distance of the ball. Therefore, the thickness t is preferably 0.32 mm or more, more preferably 0.34 mm or more.

On the other hand, when the thickness t exceeds 0.4 mm, since the center of gravity of the shaft is excessively close to the rear end side of the shaft, the weight of the head excessively increases and the club weight is increased. Swing becomes difficult even if it is the same as the conventional one. Further, since the weight is disposed at the rear end side of the shaft than at the front end thereof, the strength at the tip end side of the shaft is weakened. Therefore, the thickness t is preferably 0.38 mm or less, more preferably 0.36 mm or less.

In the present embodiment, the outer diameter d of the part from the butt end 3b of the shaft 3 to the tip of the shaft to 150 mm is 14.5 mm or more and 15.3 mm or less.

When the outer diameter d is less than 14.5 mm, the bending rigidity EI of the butt side of the shaft becomes low, and the shaft becomes soft. In addition, since the directional stability of the batted ball is deteriorated, the filling of the batted ball is deteriorated. Therefore, the outer diameter d is preferably 14.7 mm or more, more preferably 14.9 mm or more.

On the other hand, when the outer diameter d exceeds 15.5 mm, the bending rigidity value EI of the butt side of the shaft becomes high, the warpage is small, and it feels hard. Therefore, the outer diameter d is preferably 15.4 mm or less, more preferably 15.3 mm or less.

In this embodiment, the number of steps in the portion from the butt end 3b of the shaft 3 to the tip of the shaft to 400 mm is 5 or more and 8 or less.

When the number of steps is less than 5, the bending rigidity value EI of the butt side of the shaft becomes high, the warpage is small and it feels hard, so that the filling at the time of hit is deteriorated. Therefore, the number of steps is preferably 6 or more.

On the other hand, when the number of steps exceeds eight, the bending rigidity EI of the butt side of the shaft becomes low and the shaft becomes soft. In addition, since the directional stability of the batted ball is deteriorated, the filling of the batted ball is deteriorated. Therefore, the number of steps is preferably 7 or less.

In this embodiment, the content of retained austenite in the material of the shaft is smaller than that of the portion from the tip end 3a of the shaft up to 600 mm to the butt end 3b side, (3b). That is, the content of retained austenite is made different from the tip end 3a of the shaft to the butt end 3b side at a point of 600 mm, and the tip end side of the shaft and the butt end of the shaft. Specifically, the content of retained austenite in the portion of the butt side is made larger than that of the tip at the tip side than the boundary at the butt side than the boundary of 600 mm.

When the &quot; boundary &quot; is less than 600 mm from the tip end 3a of the shaft to the butt end 3b side, the bending rigidity EI of the butt side of the shaft becomes low, and the shaft becomes soft. In addition, since the directional stability of the batted ball is deteriorated, the filling of the batted ball is deteriorated. Therefore, the &quot; boundary &quot; is preferably 650 mm or more, more preferably 700 mm or more.

On the other hand, if the &quot; boundary &quot; exceeds 900 mm from the tip end 3a of the shaft toward the butt end 3b, the bending rigidity EI of the butt side of the shaft becomes high and the bending is small and hard, The peeling of the film is deteriorated. Therefore, the &quot; boundary &quot; is preferably 850 mm or less, more preferably 800 mm or less.

[Examples]

Next, the steel shaft of the present invention will be described on the basis of embodiments, but the present invention is of course not limited to these embodiments.

Using five irons with a shaft of the specifications shown in Table 1 (club length: 38 inches, club weight: 400 g), 10 golfers with actual average head speed of 42 m / s were hit by 10 balls. We carried out questionnaire about peeling of batting. Considering the ease of swinging, the directionality of the ball, and the distance, the evaluation was made in the following five stages, and the evaluation with the greatest number of arguments was adopted.

5 points: Very good

4 points: Good

3 points: normal

2 points: bad

1 point: very bad

The shaft tip strength (T point strength) was measured in accordance with the SG mark test method. The three point bending strength of the SG type is the SG type fracture strength determined by the Product Safety Association. Fig. 2 is an explanatory diagram of a method for measuring the SG type three-point bending strength. As shown in Fig. 2, the load F is applied from the upper side to the lower side at the load point t3 while supporting the shaft 3 from the lower side at the two support points t1, t2. The position of the load point t3 is a position where the support point t1 and the support point t2 are bisected. The load point t3 is made coincident with the measured point (point T), and measurement is performed.

The results of the peeling evaluation, the bending strength of the tip of the shaft, and the distance are shown in Tables 1 to 3.

[Table 1]

[표 2]

[Table 2]

[Table 3]

1 iron type golf club
2 head
3 shaft
3a tip
3b butt
4 grips
5 Shaft hole
6 Hosel
7 grip hole
G shaft center of gravity
L _G Distance from the tip of the shaft to the center of gravity of the shaft
L _S shaft length

Claims (4)

A center-of-gravity ratio Y (%) of L _G / L _S is 51.0? Y? 60.0 when the distance from the shaft tip to the shaft center-of-gravity point is L _G and the total length of the shaft is L _S ,
Shaft weight is X (g) is 80≤X≤140, the shaft total length L _S (in) a steel shaft for a golf club, characterized in that 30≤L _S ≤42. 2. The steel shaft for a golf club according to claim 1, wherein a thickness of the portion from the butt end to the shaft tip side up to 150 mm is 0.30 mm or more and 0.40 mm or less. 3. The steel shaft for a golf club according to claim 1 or 2, wherein an outer diameter of a portion up to 150 mm from the butt end to the shaft front end side is 14.5 mm or more and 15.3 mm or less. The steel shaft for a golf club according to claim 1 or 2, wherein the number of steps of the portion from the butt end to the shaft tip side of 400 mm is 5 or more and 8 or less.

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