JP2006158792A - Golf club shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a metal golf club shaft with a reduced weight and an enhanced strength. <P>SOLUTION: In the golf club shaft 10 made of a metal pipe body in which the weight of the shaft is not less than 50 g and less than 85 g, ribs 21 is formed in the inner peripheral face and/or the outer peripheral face of the shaft 10, the rigidity value (an EI value) at the position spaced 90 mm from the head side distal end 12 is in the range of 1.0 kg mm<SP>2</SP>or more and 2.5 kg mm<SP>2</SP>or less, and the shaft outer diameter D1 at the position spaced 30 mm from the head side distal end 12 is 9.5 mm or more and 15.0 mm or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a golf club shaft, and more particularly, to reduce the weight and improve the strength of a golf club shaft made of a metal cylinder.

In recent years, in order to improve the speed and stability of the hit ball, the weight is concentrated on the golf club head, and the golf club shaft tends to be reduced in weight. Therefore, a so-called carbon shaft made of a fiber reinforced resin such as a carbon prepreg having a light weight and high specific strength and specific rigidity is mainly used as a material for the golf club shaft.
However, since the carbon shaft has low torsional rigidity and weakness in the directional stability of the hit ball, the feeling and directionality of the metal shaft are being reconsidered especially for advanced players. Further, with regard to lightness, it is possible to produce a shaft made of a 90-85 g metal cylinder.

Regarding the problem of weight reduction and strength improvement of a metal golf club shaft, for example, in Japanese Patent Application Laid-Open No. 2002-58764 (Patent Document 1), cold-working of maraging steel having much higher strength and toughness than ordinary steel. It proposes to use a rolled sheet as a material. Accordingly, it is possible to provide a lightweight golf club shaft having high strength and torsional rigidity.
Japanese Patent Laid-Open No. 7-51416 (Patent Document 2) proposes coating the surface of a stainless steel material with a hard ceramic layer such as titanium carbide or titanium nitride formed by sputtering. As a result, it is possible to provide a lightweight shaft that is excellent in firmness and has a great flight distance.

However, in order to produce a shaft that can be easily swung by women and seniors using these conventional technologies, it is necessary to reduce the thickness of the material to further reduce the weight. However, if the thickness is reduced, the strength decreases. Therefore, considering the balance with strength, there is a limit to further weight reduction.
In addition, conventional metal shafts have been designed and adjusted by adjusting the shaft flexure hardness by narrowing the shaft diameter (step), but there is a change in the thickness near the step difference. There was also a problem that the stress was concentrated and the strength was lowered.

JP 2002-58764 A Japanese Patent Laid-Open No. 5-51416

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a golf club shaft that is made of metal, has high strength, and has both lightness and appropriate bending feeling.

In order to solve the above-mentioned problem, the present invention is first a golf club shaft comprising a metal cylinder having a shaft weight of 50 g or more and less than 85 g,
Ribs are provided on the inner peripheral surface and / or outer peripheral surface of the shaft, and
The rigidity value (EI value) at a position 90 mm from the head side tip is in the range of 1.0 kg · mm ^{2 to} 2.5 kg · mm ² and the shaft outer diameter at a position 30 mm from the head side tip is 9.5 mm. A golf club shaft characterized by being in the range of 15.0 mm or less is provided.

As described above, by providing ribs on the inner peripheral surface and / or outer peripheral surface, it is possible to secure an appropriate strength and flexibility, so that the overall thickness of the shaft can be reduced, and the shaft weight can be reduced. Can be reduced to 50g. In addition, it is possible to design the shaft with a lower rigidity by reducing the thickness of the base at the tip on the head side that affects the flight distance of the hit ball, so that the shaft can be bent more easily than before. As a result, the shaft can be easily swung by women and seniors, and the head speed can be increased and the flying distance of the hit ball can be extended. In addition to the rib, the outer diameter of the head side tip is within the range where the shaft outer diameter at a position 30 mm from the head side tip is 9.5 mm or more and 15.0 mm or less, as compared with the conventional general shaft. Since it is thick, it is possible to increase the strength of the head side tip that receives a strong impact when hitting a ball. Therefore, it is possible to provide a shaft that balances the ease and strength of the head-side tip and the lightness of the shaft in a well-balanced manner.
Furthermore, since the bending stiffness can be changed by adjusting the rib spacing and the rib angle with respect to the shaft axis, there is no need to narrow down the shaft diameter as in the conventional case, and the step point for changing the base wall thickness is eliminated. Damage due to stress concentration can also be prevented.

  The shaft weight is set to 50 g or more and less than 85 g. If the shaft is less than 50 g, a long shaft cannot be produced, and the strength sufficient to withstand the stress against the bending of the shaft cannot be secured. This is because the speed does not increase and the hit distance of the hit ball cannot be extended. The shaft weight is preferably 52 g or more and 80 g or less, more preferably 54 g or more and 70 g or less, and particularly preferably 55 g or more and 65 g or less.

The reason why the rigidity value at the position of 90 mm from the head side tip is defined is that the position is easily subjected to stress during the swing.
The stiffness value of the position of 90mm from the head side tip, are we 1.0 kg · mm ² or more 2.5 kg · mm ² within the following range, it is less than 1.0 kg · mm ^2, easy bending very soft This is because it becomes too easy to be damaged by metal fatigue. On the other hand, if it is larger than 2.5 kg · mm ² , the head side becomes too hard, which is due to a decrease in deflection at the time of hitting and a flight distance. This rigidity value is further 1.2 kg · mm ² or more, particularly 1.3 kg · mm ² or more, preferably 2.4 kg · mm ² or less, particularly preferably 2.3 kg · mm ² or less.

  The outer diameter at the position 30 mm from the head-side tip is defined as the portion that is inserted and bonded to the neck hole of the head, and this position corresponds to the end surface of the head neck. It depends on. The outer diameter at a position 30 mm from the tip on the head side is 9.5 mm or more and 15.0 mm or less. If the diameter is less than 9.5 mm, it tends to bend, but the strength is reduced. This is because the thickness becomes too thin and the strength decreases. The lower limit of the outer diameter of the shaft at this position is more preferably 9.3 mm or more, particularly preferably 9.4 mm or more, while the upper limit is more preferably 14.0 mm or less, particularly preferably 13.5 mm or less.

A rib may be provided on either or both of the inner peripheral surface and the outer peripheral surface of the shaft, but it is preferable to provide the rib on the inner peripheral surface from the viewpoint that the outer fitting can be made smooth.
The ribs are preferably formed continuously on the entire circumference of the shaft and also in the length direction so that the strength can be ensured equally with respect to twisting and bending in both the left and right directions.

Examples of the rib shape include the following (1) to (5).
(1) Mesh shape in which spiral ribs are crossed by inclining in the plus or minus direction with respect to the shaft axis;
The angle of the rib with respect to the shaft axis is preferably ± 20 ° to ± 60 °, particularly preferably ± 30 ° to ± 45 °.
(2) Honeycomb with continuous polygonal frame ribs;
(3) A lattice shape in which ribs in a direction parallel to the shaft axial direction intersect with ribs in the orthogonal direction;
(4) A shape in which a triangular frame-shaped rib having a rib in a direction perpendicular to the shaft axis direction as one side is continuously provided;
(5) A shape in which ribs in a direction perpendicular to the axial direction of the shaft and a direction perpendicular to the axial direction are provided as diagonal lines, and a rhombus frame continuously connecting the apexes is provided.

With the shape of (1), it can be strengthened mainly against stress in the twisting direction. And torque can be changed by changing the interval and angle of the spiral.
With the shape of (2), it is possible to strengthen against any stress in the twisting direction, the bending direction in the shaft axial direction, and the crushing direction orthogonal to the shaft axial direction.
With the shape of (3), it can be strengthened mainly with respect to the bending direction in the shaft axial direction (0 degree) and at the same time with respect to the stress in the crushing direction of 90 degrees with respect to the shaft axial direction.
With the shape of (4), it can be strengthened against stress in the twisting direction and crushing direction.
If it is the shape of said (5), it can strengthen with respect to the stress of any direction of a twist direction, a crushing direction, and a bending direction.

Moreover, it is preferable that at least a part of the rib is formed in a region from the tip on the head side of the shaft to a position of 200 mm or at least a part of the region.
Since the region receives the strongest impact at the time of hitting and has a large amount of deformation, by providing ribs on the inner peripheral surface of this region (hereinafter referred to as “head side reinforcing region”), the shaft strength can be effectively increased. Can be increased.
The rib may be provided over the entire length of the shaft, or may be provided only in a part of the head side reinforcing region.

The protruding height of the rib is 0.1 mm to 1.0 mm, preferably 0.2 mm or more, particularly 0.3 mm or more, and preferably 0.9 mm or less, particularly 0.8 mm or less. The width is 0.1 mm to 1.0 mm, preferably 0.2 mm or more, particularly 0.3 mm or more, and preferably 0.9 mm or less, particularly 0.8 mm or less.
The rib may be integrally projected from the inner peripheral surface of the shaft made of a metal cylinder and / or the outer peripheral surface by forging, pressing, or the like, or may be formed by welding a metal wire.
Specifically, a metal belt-shaped member having the rib formed on one surface or both surfaces by press molding is wound in a tubular shape, and both surface portions of the belt-shaped member are welded to form the metal cylinder. It is preferable.

Secondly, the present invention is a golf club shaft made of a metal cylinder that is 50 g or more and less than 85 g,
Ribs are provided on the inner peripheral surface of the shaft,
At least a part of the rib is formed in a part including a region corresponding to 30% or more and 40% or less of the total length of the shaft from the grip side rear end, or a portion of the region corresponding to at least 35% of the total length of the shaft from the grip side rear end. cage, and provides a golf club shaft, wherein the rigidity value of the region is in the range of 3.5 kg · mm ² or more 8.0 kg · mm ² or less.

That is, an area corresponding to a length of 30% to 40% of the total length of the shaft from the rear end on the grip side is a part that affects the feeling at the time of hitting, and therefore this area (hereinafter referred to as “grip side reinforcement area”). A good feeling can be obtained by providing ribs to increase the hand rigidity.
In addition, the grip side rear end portion is thicker, while thin, and tends to be reduced in rigidity and strength. In particular, this tendency is remarkable in a lightweight shaft of 50 g or more and less than 85 g. By providing the ribs in the reinforcing region, it is possible to ensure the necessary strength while suppressing an increase in thickness.

  The rib may be formed beyond the grip-side reinforcement region, but is preferably formed only within the grip-side reinforcement region. This is because the portion beyond the reinforcing region on the grip side has a low necessity for reinforcement, and when the rib forming range is expanded, the shaft weight increases and the shaft is difficult to swing.

Are we the grip-side reinforcing within 3.5 kg · mm ² or more 8.0 kg · mm ² or less stiffness value of the region has a large bending is less than 3.5 kg · mm ^2, is prone fatigue fracture, When it is larger than 8.0 kg · mm ² , the rib becomes thicker or higher, and therefore, the shaft weight increases. The lower limit of the rigidity value is more preferably 3.7 kg · mm ² or more, and particularly preferably 3.9 kg · mm ² or more. The upper limit is more preferably less 7.8 kg · mm ^2, particularly 7.6 kg · mm ² or less.

In addition, the shape of a rib is made into the shape of said (1)-(5) etc., and the height and width of a rib are also equivalent to the above.
The ribs are also preferably provided on the inner peripheral surface of the shaft, but may be provided on the outer peripheral surface.

  The total length of the shaft is preferably 850 mm or more and 1194 mm or less. This is because if the length is less than 850 mm, the length is too short, and the centrifugal force does not work at the time of swing, so the flying distance does not come out, and the shaft longer than 1194 mm is too long and the meet ratio decreases, the directionality varies, and off-center This is because the number of hits increases and the club does not fly. The total shaft length is further preferably 855 mm or more and 1181 mm or less, and particularly preferably 860 mm or more and 1168 mm or less.

  The thickness of the shaft (the thickness of the base excluding the ribs) is preferably 0.15 mm or more and 0.70 mm or less. This is because if it is less than 0.15 mm, it is difficult to secure the required strength even if ribs are formed, and if it is thicker than 0.70 mm, the weight increases and the shaft becomes difficult to swing. The lower limit of the wall thickness is more preferably 0.20 mm or more, particularly 0.25 mm or more, and the upper limit is more preferably 0.65 mm or less, and particularly preferably 0.60 mm or less.

  As described above, according to the present invention, since the rigidity and strength can be ensured by forming the rib in the shaft made of the metal cylindrical body, the base wall thickness of the shaft can be reduced, which is lighter than before. Thus, the metal golf club shaft is provided with an appropriate degree of flexibility and has a required strength. Further, by forming a rib at the grip side rear end portion, the hand rigidity is increased and the feeling during swing is improved, so that it is easy to swing and the flight distance can be extended.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 3 show a golf club shaft 10 according to a first embodiment of the present invention.
The golf club shaft 10 has a rib 21 formed on the entire inside of a tapered steel pipe main body 11, a head 14 is attached to a head end 12 on the small diameter side, and a grip side rear end 13 on the large diameter side. A grip 15 is attached to the. The total length L of the shaft 10 is 955 mm, and the weight is 65 g.

  As shown in FIG. 3A, the shaft 10 has a surface 11a on which ribs 20 are formed by press molding on the entire surface of one surface side of a steel strip (band member) 11 ′ having a thickness of 0.2 mm. The steel strip 11 'is formed into a cylindrical shape with' inside ', and the winding surface of the steel strip is welded to form a pipe. At this time, as shown in FIG. 2, the outer diameter D1 at a position 30 mm from the head-side tip 12 is 9.5 mm.

  Specifically, spiral ribs 20a inclined by + 45 ° with respect to the axis X direction of the shaft 10 are press-molded at intervals of 15 mm. Further, spiral ribs 20b inclined at −45 ° with respect to the axial direction X of the shaft 10 are press-formed in parallel at intervals of 15 mm, the spiral ribs 20a and 20b are crossed with each other, and a mesh is formed on the entire surface of the strip 11 ′. The rib 21 continued in a shape is provided. As shown in FIG. 3B, the protruding height H1 of the rib 21 from the surface of the strip 11 'is 0.3 mm.

The shaft 10 in which the rib 21 is formed on the entire inner peripheral surface is provided with the rib 21 in the head side reinforcing region 16 from the head side tip 12 to the position of 200 mm, which is the portion with the largest deformation amount at the time of hitting. The rigidity value at a position 90 mm from the head-side tip 12 is set to be 1.4 kg · mm ² within the range of 1.0 kg · mm ^{2 to} 2.5 kg · mm ² .

On the other hand, the grip side reinforcement region from the position 17a where the distance from the grip side rear end 13 corresponds to 30% of the total length L of the shaft 10 to the position 17b where the distance from the grip side rear end 13 corresponds to 40% of the total length L of the shaft 10 In 17, the stiffness value is. Is set to 4.2 kg · mm ² of 3.5 kg · mm ² or more 8.0 kg · mm ² within the following ranges.

  Since the shaft 10 having the above-described configuration has the rib 21 formed on the entire inner peripheral surface thereof, the pipe body 11 can be made thin and the strength can be ensured. In particular, since the spiral ribs 21 inclined with respect to the axial direction of the shaft 10 are intersected and continuously formed over the entire circumference and the entire length of the shaft 10, the strength can be increased against stress in the torsional direction. it can.

Further, the shaft 10 is light and easy to swing, and can also have a moderate feeling of bending.
That is, in the head side reinforcement region 16 from the head side tip 12 to the position of 200 mm, which is the portion where the deformation amount at the time of hitting is the largest, the rigidity value is 1.0 kg · mm ² or more and 2.5 kg · mm ² or less. Since it is softer and more flexible than a general shaft, it is possible to extend the flight distance of the hit ball.
On the other hand, the shaft outer diameter D1 at a position 30 mm from the head-side tip 12 is set to 9.5 mm, which is thicker than the conventional general shaft, to increase the strength of the head-side reinforcing region 16 that receives a strong impact.
Further, the stiffness value of the grip-side reinforcing region 17 because it has a 3.5 kg · mm ² or more 8.0 kg · mm ² within the following ranges, hand stiffness is increased, it is possible to feel when hitting is good .

  4 and 5A and 5B show a second embodiment of the present invention, in which ribs 22 are formed in a honeycomb shape on the inner peripheral surface of the shaft 10. In other respects, the configuration is the same as that of the first embodiment.

  Specifically, after forming the honeycomb-shaped rib 22 by pressing the steel strip 11 ′ with a honeycomb-shaped mold, the shaft 10 is formed by forming the surface 11a ′ on which the rib 22 is formed into a pipe shape. is doing. The protrusion height H2 of the rib 22 from the surface of the strip 11 'is 0.3 mm. The shaft outer diameter D2 at a position 30 mm from the head-side tip 12 is 10.1 mm, and the shaft weight is 55 g.

Also in this embodiment, since the rib 22 is formed on the inner peripheral surface of the shaft 10, the thickness of the pipe body 11 can be reduced to further reduce the weight, and the strength can be provided. In particular, as shown in FIG. 5A, by forming the ribs 22 in a honeycomb shape, the shaft strength can be increased not only in the twisting direction but also in the bending direction and the crushing direction.
Further, by providing the rib 22, the rigidity value at the position of 90 mm from the head side tip 12 is 1.5 kg · mm ² as in the first embodiment, which is compared with the conventional general shaft. And it is soft and easy to bend. In addition, the shaft outer diameter D2 at a position 30 mm from the head side tip 12 is made thicker than the conventional general shaft, and the rigidity value of the grip side reinforcing region 17 is set to 4.5 kg · mm ² to increase the hand rigidity. Yes.

  6 and 7 show a third embodiment of the present invention, in which a spiral rib 23 is formed on the inner peripheral surface of the shaft 10, but the rib 23A is not formed on the entire length of the shaft 10, but on the head. The rib 23B is provided separately on the grip side.

Specifically, the head side rib 23A is in a region from the head side tip 12 of the shaft 10 to 180 mm, and the grip side rib 23B is in a region from the grip side rear end 13 to 200 mm (about 21% of the total shaft length L). Each is formed continuously in the circumferential direction.
The inclination, shape, and formation method of the spiral rib 23 with respect to the shaft axis X direction are the same as those of the spiral rib 21 of the first embodiment. However, as shown in FIG. The protrusion height H3 from the surface is set to 0.5 mm.

The outer diameter D3 at a position 30 mm from the head-side tip 12 is 9.5 mm, and the shaft weight is 65 g.
In addition, the rigidity value is 1.4 kg · mm ² at a position 90 mm from the head-side tip 12, and the rigidity value of the grip-side reinforcement region 17 is 6.5 kg · mm ² .

  In the third embodiment, the head-side rib 23A is formed in the most part of the head-side reinforcing region 16 that receives a large impact when hitting a ball, and a part of the grip-side reinforcing region 17 that affects the feeling during swinging. Since the grip-side ribs 23B are formed so as to include, the strength can be effectively increased while suppressing an increase in the weight of the shaft 10. In particular, since the protrusion height H3 of the rib 23 is large, especially in the grip side reinforcing region 17 in which the grip side rib 23B is formed, the rigidity value is further increased, and a firm feeling at the hand is strengthened, so the off-shot is reduced, The flight distance of the hit ball can be extended.

  8 and 9 show a fourth embodiment of the present invention, in which honeycomb-shaped ribs 24 are formed on the inner peripheral surface of the shaft 10 separately into head-side ribs 24A and grip-side ribs 24B. The point is the same as that of the third embodiment.

  That is, the head side rib 24A is in the region from the head side tip 12 of the shaft 10 to 180 mm, and the grip side rib 24B is in the region from the grip side rear end 13 to 200 mm (about 21% of the total shaft length L). It is formed continuously in the circumferential direction. The formation method of the honeycomb-like rib 24 is the same as that of the honeycomb-like rib 22 of the second embodiment. However, as shown in FIG. 9, the protrusion height H4 of the rib 24 from the surface of the strip 11 ′ is 0.5 mm.

The outer diameter D4 at a position 30 mm from the head-side tip 12 is 10.1 mm, and the shaft weight is 55 g.
Further, the rigidity value is 1.5 kg · mm ² at a position 90 mm from the head-side tip 12, and the rigidity value of the grip-side reinforcement region 17 is 7.8 kg · mm ² .

  As in the third embodiment, the shaft of the fourth embodiment has very high hand rigidity and a firm feeling, and is lighter than the third embodiment. The head speed is increased and the hitting distance can be further increased.

In addition, this invention is not limited to the said embodiment. In addition to forming ribs on the inner peripheral surface of the shaft 10, ribs may be formed on the outer peripheral surface on the head side and / or grip side, or ribs may be formed on both the inner peripheral surface and the outer peripheral surface. Good.
In the case where ribs are formed on the outer peripheral surface of the shaft, design can be imparted. And when providing in both an outer peripheral surface and an internal peripheral surface, while providing the rib of an internal peripheral surface in the whole shaft surface, you may provide an outer peripheral surface in a part of head reinforcement area | region and a part of grip reinforcement area | region.

The shape of the rib may also be a shape in which a triangular frame-like rib 25 having a rib in the direction orthogonal to the shaft axis direction (circumferential direction) as one side is continuously provided as shown in FIG.
Further, as shown in FIG. 10B, a rectangular frame-shaped rib 26 in which ribs 26a in the axis X direction of the shaft 10 and ribs 26b in the circumferential direction intersect in a lattice shape may be used.
Furthermore, as shown in FIG. 10C, a rhombus shape 27 having a diagonal line in a direction perpendicular to the axial direction and the axial direction may be continuous.
In FIGS. 10A to 10C, the rib is indicated by a single solid line, but has the above-described width.
Furthermore, as described above, the ribs may be formed in a dotted manner as protrusions such as a triangular shape or a circular shape instead of a continuous linear shape.

  Further, the ribs may be formed on a part of the head side reinforcing region 16 or on the grip side, or on a part of the grip side reinforcing region 17 or on the grip side and / or the head side. Good.

(Example)
Hereinafter, Examples 1-4 and Comparative Examples 1-4 of the golf club shaft of the present invention will be described in detail. In addition, although the effect of this invention is clarified by the Example, this invention is not limited to an Example.

As shown in Table 1 below, the weight of the golf club shaft 10, the outer diameter at a position 30 mm from the head-side tip 12, the shape of the internal rib, the formation position of the internal rib, the protruding height of the internal rib, and the head-side tip 12 Examples 1 to 4 and Comparative Examples 1 to 4 in which the rigidity (EI) value at the position of 90 mm and the rigidity (EI) value of the grip side reinforcement region 17 are made different are produced, and each of the three points on the head side and the grip side The bending strength and the flying distance of the hit ball were measured, and the ease of swinging was examined by an actual hit test. The results are shown in Table 1.
Each of Examples 1 to 4 and Comparative Examples 1 to 4 was a steel shaft having a total length of 955 mm, and the manufacturing method thereof was the same as that of each of the above embodiments. Moreover, all the internal ribs of Examples 1 to 4 were continuously formed on the entire circumference of the shaft 10.

(Measurement method of rigidity value)
As a measuring method of the rigidity value EI, the universal material testing machine 50 was used, and the measurement was performed by bending the shaft 10 by three-point bending as shown in FIG. The rigidity value was calculated by the following formula. The shaft 10 was placed on the jigs 52A and 52B so that the measurement point P1 was located under the indenter 51 of the universal material testing machine 50. The interval between the jigs 52A and 52B was 200 mm. The curvature of the tip of the indenter 51 was 75R, and the curvature of the tips of the jigs 52A and 52B was 2R. The indenter 51 was lowered at a test speed of 5 mm / min, and the shaft 10 was bent. When the applied load reached 20 kgf, the movement of the indenter 51 was completed, and the amount of deflection of the shaft 10 at that time was measured.

(Rigidity calculation)
EI (kg · mm ² ) = (maximum load F × distance ² between support points) ÷ (48 × deflection)

Example 1
The configuration is the same as that of the first embodiment. That is, the shaft weight is 65 g, the outer diameter of 30 mm from the head-side tip 12 is 9.5 mm, the internal rib shape is the intersecting spiral rib 21, the internal rib 21 is formed at the full length of the shaft 10, and the internal rib 21 protrudes The height was 0.3 mm, the stiffness (EI) value at a position 90 mm from the head-side tip 12 was 1.4 kg · mm ² , and the stiffness (EI) value of the grip-side reinforcement region 17 was 4.2 kg · mm ² .

(Example 2)
The configuration is the same as that of the second embodiment. That is, the shaft weight is 55 g, the outer diameter of 30 mm from the head side tip 12 is 10.1 mm, the shape of the internal rib is the honeycomb-like rib 22, the formation position of the internal rib 22 is the total length of the shaft 10, and the protruding height of the internal rib 22 Was 0.3 mm, the stiffness (EI) value at a position 90 mm from the head-side tip 12 was 1.5 kg · mm ² , and the stiffness (EI) value of the grip-side reinforcement region 17 was 4.5 kg · mm ² .

(Example 3)
The configuration is the same as that of the third embodiment. That is, the shaft weight is 65 g, the outer diameter of 30 mm from the head-side tip 12 is 9.5 mm, the shape of the inner rib is the spiral rib 23, and the formation position of the inner rib 23 is the region from the head-side tip 12 of the shaft 10 to 180 mm. And the region from the grip side rear end 13 to 200 mm, the protruding height of the internal rib 23 is 0.5 mm, and the stiffness (EI) value at the position 90 mm from the head side tip 12 is 1.4 kg · mm ² , grip side reinforcement The rigidity (EI) value of the region 17 was 6.5 kg · mm ² .

Example 4
The configuration is the same as that of the fourth embodiment. That is, the shaft weight is 55 g, the outer diameter of 30 mm from the head side tip 12 is 10.1 mm, the shape of the internal rib is the honeycomb-like rib 24, and the formation position of the internal rib 24 is the region from the head side tip 12 of the shaft 10 to 180 mm And the region from the grip side rear end 13 to 200 mm, the protruding height of the internal rib 24 is 0.5 mm, and the rigidity (EI) value at the position 90 mm from the head side tip 12 is 1.5 kg · mm ² , grip side reinforcement The rigidity (EI) value of the region 17 was 7.8 kg · mm ² .

(Comparative Example 1)
No internal ribs are provided, the bending hardness is adjusted by narrowing the shaft diameter (step), and the rigidity values of the head side tip and the grip side reinforcing region are both lower than those of the above embodiments, and the shaft is easy to bend. did. Specifically, the shaft weight is 120 g, the outer diameter at a position 30 mm from the head-side tip 12 is 9.2 mm, the rigidity (EI) value at a position 90 mm from the head-side tip 12 is 0.9 kg · mm ² , and the grip side reinforcement region The stiffness (EI) value of 17 was 3.4 kg · mm ² .

(Comparative Example 2)
The wall thickness was made thinner than Comparative Example 1 to reduce the weight. Specifically, the shaft weight is 90 g, the outer diameter at a position 30 mm from the head-side tip 12 is 9.2 mm, the rigidity (EI) value at a position 90 mm from the head-side tip 12 is 0.6 kg · mm ² , and the grip side reinforcement region The stiffness (EI) value of 17 was 2.8 kg · mm ² .

(Comparative Example 3)
The wall thickness was made slightly thinner than Comparative Example 1 to reduce the weight. Specifically, the shaft weight is 95 g, the outer diameter at a position 30 mm from the head-side tip 12 is 9.2 mm, the rigidity (EI) value at a position 90 mm from the head-side tip 12 is 0.7 kg · mm ² , and the grip side reinforcement region The stiffness (EI) value of 17 was 3 kg · mm ² .

(Comparative Example 4)
Although the wall thickness was made thinner and lighter than Comparative Example 2, the outer diameter of the head-side tip was thickened. Specifically, the shaft weight is 89 g, the outer diameter at a position 30 mm from the head-side tip 12 is 10 mm, the stiffness (EI) value at a position 90 mm from the head-side tip 12 is 1.2 kg · mm ² , and the grip-side reinforcement region 17 The rigidity (EI) value was 2.7 kg · mm ² .

(Measurement of three-point bending strength)
Under the same test conditions as the measurement of the rigidity value, a load was applied until the shaft 10 was broken, and the load at the time of occurrence of the breakage was measured. The measurement point P1 was set at two positions, a position 90 mm from the head-side tip 12 of the shaft 10 and a position 175 mm from the grip-side rear end 13 of the shaft 10.

(Actual test)
One tester hit 20 balls at an iron # 5 club using each of the shafts above, and performed a sensory evaluation on the ease of swinging the club. The results are shown in Table 1.

(Measurement of flight distance)
The tester hit 20 balls with an iron # 5 club using each shaft, and the average of the flight distance (yard) of all the hit balls is shown in Table 1.

  As can be seen from the results in Table 1, each of Examples 1 to 4 is higher in strength on both the head side and the grip side than in Comparative Examples 1 to 4, and is easy to swing. Also became larger. This seems to be because Examples 1 to 4 attempted to reduce the weight of the shaft while forming ribs inside to ensure strength. In particular, the head-side tip portion is required to have a strength against a strong impact and an appropriate bend that extends the flight distance, but all of Examples 1 to 4 have both. Further, the grip side rear end portion is required to have a firm feeling at the time of swinging, but each of Examples 1 to 4 has high hand rigidity, which seems to have led to favorable evaluation of ease of swinging in an actual hit test.

  On the other hand, in Comparative Examples 1 to 4, it seems that the change in thickness was present due to narrowing of the shaft diameter, the head-side tip was thin, and the rigidity value was too low, which caused low strength. . In addition, the weight of the shaft was heavy, and the rigidity at hand was not high. Therefore, it was evaluated that it was difficult to swing in the actual hit test, and the flight distance did not increase.

  Comparing Examples 1 to 4, Examples 3 and 4 in which internal ribs having a large protruding height are provided only at the head-side front end part and the grip-side rear end part are provided in Example 1 in which low ribs are provided over the entire length Compared to 2, the hand rigidity was higher, and in the actual hit test, both swinging ease and flight distance were good.

1 is a schematic view of a golf club according to a first embodiment of the present invention. It is sectional drawing of the shaft of the golf club shown in FIG. It is an enlarged view which shows the rib shape before pipe making of the shaft shown in FIG. 2, (A) is a schematic plan view, (B) is sectional drawing. It is sectional drawing of the golf club shaft which concerns on 2nd Embodiment of this invention. It is an enlarged view which shows the rib shape before pipe making of the shaft shown in FIG. 4, (A) is a schematic plan view, (B) is sectional drawing. It is sectional drawing of the golf club shaft which concerns on 3rd Embodiment of this invention. It is an expanded sectional view before the pipe making of a shaft which shows the rib shape shown in FIG. It is sectional drawing of the golf club shaft which concerns on 4th Embodiment of this invention. It is an expanded sectional view before the pipe making of a shaft which shows the rib shape shown in FIG. (A) (B) (C) is a top view which shows the shape of another internal rib. It is a figure which shows the measuring method of a rigidity value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Golf club shaft 11 Pipe main body 11 'Band steel 12 Head side front end 13 Grip side rear end 16 Head side reinforcement area 17 Grip side reinforcement area 21, 23 Spiral ribs 22, 24 Honeycomb ribs

Claims (6)

A golf club shaft made of a metal cylinder having a shaft weight of 50 g or more and less than 85 g,
Ribs are provided on the inner peripheral surface and / or outer peripheral surface of the shaft, and
The rigidity value (EI value) at a position 90 mm from the head side tip is in the range of 1.0 kg · mm ^{2 to} 2.5 kg · mm ² and the shaft outer diameter at a position 30 mm from the head side tip is 9.5 mm. A golf club shaft characterized by being in the range of 15.0 mm or less.   2. The golf club shaft according to claim 1, wherein the rib protrudes from an inner peripheral surface of the shaft, and at least a part thereof is formed in a region from a head side tip of the shaft to a position of 200 mm or at least a part of the region. .   The ribs are uniformly formed over the entire length in the circumferential direction, and the rib shape is a mesh-like or polygonal frame rib in which spiral ribs are crossed by inclining in the plus or minus direction with respect to the shaft axis. A honeycomb shape, a lattice shape in which ribs in a direction parallel to the shaft axial direction and a rib in the orthogonal direction intersect, a shape in which a triangular frame-shaped rib having a rib in a direction perpendicular to the shaft axial direction as one side is provided, or 3. The golf club shaft according to claim 1, wherein a rhombus frame having a shaft axial direction and a diagonal line orthogonal to the axial direction is formed into a continuous shape. A golf club shaft made of a metal cylinder having a size of 50 g or more and less than 85 g,
Ribs are provided on the inner peripheral surface and / or outer peripheral surface of the shaft,
At least a part of the rib is formed in a part including a region corresponding to 30% or more and 40% or less of the total length of the shaft from the grip side rear end, or a portion of the region corresponding to at least 35% of the total length of the shaft from the grip side rear end. And
Golf club shaft, wherein the rigidity value of the region is in the range of 3.5 kg · mm ² or more 8.0 kg · mm ² or less.   The golf club shaft according to any one of claims 1 to 5, wherein a protruding height of the rib is 0.1 mm to 1.0 mm and a width is 0.1 mm to 1.0 mm.   The metal strip-shaped member in which the rib is formed on one surface or both surfaces by press molding is wound in a tubular shape, and both sides of the strip-shaped member are welded to form the metal cylinder. 7. The golf club shaft according to any one of items 6.

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