WO2023286324A1 - Golf shaft and manufacturing method for same - Google Patents

Golf shaft and manufacturing method for same Download PDF

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Publication number
WO2023286324A1
WO2023286324A1 PCT/JP2022/008647 JP2022008647W WO2023286324A1 WO 2023286324 A1 WO2023286324 A1 WO 2023286324A1 JP 2022008647 W JP2022008647 W JP 2022008647W WO 2023286324 A1 WO2023286324 A1 WO 2023286324A1
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WO
WIPO (PCT)
Prior art keywords
golf shaft
distal end
end portion
outer diameter
intermediate point
Prior art date
Application number
PCT/JP2022/008647
Other languages
French (fr)
Japanese (ja)
Inventor
甲介 藤原
Original Assignee
日本発條株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本発條株式会社 filed Critical 日本発條株式会社
Priority to CN202280035236.1A priority Critical patent/CN117440854A/en
Priority to KR1020237037510A priority patent/KR20230162105A/en
Priority to EP22841674.9A priority patent/EP4371630A1/en
Publication of WO2023286324A1 publication Critical patent/WO2023286324A1/en

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    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B60/00—Details or accessories of golf clubs, bats, rackets or the like
    • A63B60/42—Devices for measuring, verifying, correcting or customising the inherent characteristics of golf clubs, bats, rackets or the like, e.g. measuring the maximum torque a batting shaft can withstand
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00—Golf clubs
    • A63B53/12—Metallic shafts
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B53/00—Golf clubs
    • A63B53/10—Non-metallic shafts
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B60/00—Details or accessories of golf clubs, bats, rackets or the like
    • A63B60/0081—Substantially flexible shafts; Hinged shafts
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2102/00—Application of clubs, bats, rackets or the like to the sporting activity ; particular sports involving the use of balls and clubs, bats, rackets, or the like
    • A63B2102/32—Golf

Definitions

  • the present invention relates to a golf shaft that achieves low trajectory and low spin, and a method for manufacturing the same.
  • a ball with such a high trajectory and low spin is easily affected by the wind and may not travel a long distance. In this case, it is advantageous to use a ball with a low trajectory and low spin.
  • this low trajectory and low spin ball can be achieved by improving the rigidity of the tip of a golf shaft, but simply improving the rigidity of the tip was not sufficient.
  • the present invention has a stiffness distribution in which the stiffness gradually increases from the distal end portion to the proximal end portion, the stiffness distribution has an intermediate point where the slope changes in an intermediate portion between the distal end portion and the proximal end portion, and the distal end portion and the intermediate point is 3.00 kgf ⁇ m 2 to 5.00 kgf ⁇ m 2 , and the difference in stiffness between the intermediate point and the base end is 2.00 kgf ⁇ m 2 or less.
  • the present invention also provides a method for manufacturing a golf shaft having a stiffness distribution in which the stiffness gradually increases from the distal end portion to the proximal end portion, wherein an intermediate portion between the distal end portion and the proximal end portion is a main body portion.
  • a basic shape having a plurality of adjusting stepped portions with different outer diameters located on the tip side with respect to the main body portion and a straight portion with a constant outer diameter located on the tip side with respect to the adjusting stepped portion
  • a method for manufacturing a golf shaft wherein the length of the proximal end is axially extended by one or more adjustment steps, and the adjustment steps corresponding to the amount of extension of the length of the proximal end are eliminated. do.
  • the rigidity of the tip end and the base end can be appropriately set in relation to the midpoint to obtain sufficiently low trajectory and low spin.
  • the golf shaft manufacturing method of the present invention it is possible to easily develop a plurality of flexes in a golf shaft having a gradual increase in stiffness from the tip to the base, including a golf shaft that provides sufficiently low trajectory and low spin. can.
  • FIG. 1 is a side view of a golf shaft according to Example 1 of the present invention.
  • FIG. 2 is a graph showing the stiffness distribution of the golf shaft of FIG. 1;
  • FIG. 3 is a chart showing the launch angle and spin amount of the golf shaft of FIG. 1 together with a comparative example.
  • FIG. 4 is a graph showing the stiffness distribution of FIG. 2 together with the stiffness distribution of a comparative example.
  • FIG. 5 is a side view showing a basic golf shaft used in the golf shaft manufacturing method according to the first embodiment of the present invention.
  • 6A to 6D are side views showing golf shafts with different flexes.
  • FIGS. 7A and 7B are charts showing the stiffness of the tip, midpoint, and proximal ends of the golf shafts of FIGS. 6A-6D along with the corresponding stiffnesses of a comparative example.
  • the goal of obtaining a sufficiently low trajectory and low spin was achieved through the rigidity distribution of the golf shaft.
  • the golf shaft (1) has a stiffness distribution in which the stiffness gradually increases from the distal end (5) to the proximal end (7).
  • this stiffness distribution there is an intermediate point (P) where the slope changes in the intermediate portion (9) between the distal end (5) and the proximal end (7), and is 3.00 kgf ⁇ m 2 to 5.00 kgf ⁇ m 2 , and the difference in stiffness between the intermediate point (P) and the base end ( 7 ) is 2.00 kgf ⁇ m 2 or less.
  • the intermediate point (P) may be positioned within a range of 40% to 60% of the total length from the tip of the golf shaft (1).
  • the golf shaft (1) has a stepped shape in which the outer diameter gradually increases between a distal end (5) and a proximal end (7).
  • the difference in outer diameter between adjacent steps (17) from midpoint (P) to proximal end (7) is smaller than the difference in outer diameter between adjacent steps (17) to P).
  • the golf shaft manufacturing method is a method of manufacturing a golf shaft (1) having a stiffness distribution in which the stiffness gradually increases from the distal end (5) to the proximal end (7).
  • the intermediate portion (9) between the distal end portion (5) and the proximal end portion (7) includes a body portion (11) and an outer portion located distally with respect to the body portion (11).
  • the outer diameter of the straight portion (15) may be the same as the largest outer diameter of the removed adjustment stepped portions (13).
  • FIG. 1 is a side view of a golf shaft according to Example 1 of the present invention.
  • the golf shaft 1 of this embodiment is a metal shaft, and consists of a metal hollow tubular body.
  • the golf shaft 1 has a gradually increasing outer diameter with a generally stepped shape.
  • the cross-sectional shape of the golf shaft 1 is circular. It should be noted that the outer diameter of the golf shaft 1 may be tapered in whole or in part, instead of the stepped shape. Moreover, the cross-sectional shape of the golf shaft 1 may be other shapes such as an ellipse.
  • the length of the golf shaft 1 is 37-41 inches (about 93.98-104.14 cm). However, the golf shaft 1 can be set shorter than 37 inches or longer than 41 inches. Further, the material of the golf shaft 1 is steel, but other materials may be used. Other materials include other metals such as aluminum, titanium and their alloys, non-metals such as CFRP, and composite materials in which metals and non-metals are combined.
  • the golf shaft 1 is composed of a distal end portion 5 , a proximal end portion 7 and an intermediate portion 9 .
  • the tip portion 5 is the tip portion in the axial direction, and refers to an area within a predetermined range from the tip of the golf shaft 1 in the axial direction.
  • the tip portion 5 of this embodiment is a portion to which the head of the golf club is attached.
  • the distal end portion 5 is tapered such that the outer diameter gradually increases toward the base end of the golf shaft 1 .
  • the tip portion 5 may be formed in a straight shape with a constant outer diameter.
  • the proximal end portion 7 is the proximal end portion of the golf shaft 1 in the axial direction, and refers to a region within a predetermined range from the proximal end of the golf shaft 1 in the axial direction.
  • the base end portion 7 of this embodiment is a portion to which the grip of the golf club is attached.
  • the base end portion 7 is formed in a straight shape with a constant outer diameter, but it may be tapered so that the outer diameter changes slightly toward the base end side.
  • the intermediate portion 9 is a portion located between the distal end portion 5 and the proximal end portion 7, and is composed of a body portion 11, a plurality of adjustment stepped portions 13, a straight portion 15, and a tapered portion 16. .
  • the main body part 11 is a part formed in a stepped shape as a whole, and is composed of a plurality of stepped parts 17 .
  • the outer diameters of the plurality of stepped portions 17 gradually increase toward the base end side.
  • Each stepped portion 17 has a constant outer diameter, but the outer diameter may be gradually increased toward the base end side.
  • the stepped shape of the main body portion 11 is such that the adjacent steps 17 from the intermediate point P to the base end 7 are closer to each other than the difference in outer diameter between the adjacent step portions 17 from the distal end 5 to the intermediate point P (see FIG. 2).
  • a difference in outer diameter between the stepped portions 17 is small.
  • the difference in the outer diameter between the stepped portion 17 and the stepped portion 17 positioned immediately before or after the stepped portion 17 determines the outer diameter of the stepped portion 17 up to that point. It should be smaller than the difference.
  • the stepped portion 17 from the intermediate point P to the base end portion 7 is set to be longer in the axial direction than the stepped portion 17 from the distal end portion 5 to the intermediate point P. As shown in FIG.
  • the body portion 11 is a portion whose shape does not change regardless of variations in the flex of the golf shaft 1 .
  • the flex of the golf shaft 1 is the hardness of the golf shaft 1 , and even the same golf shaft 1 generally has a plurality of variations.
  • a plurality of adjustment stepped portions 13 are stepped portions for adjusting the flex of the golf shaft 1 .
  • the number of these adjustment steps 13 decreases as the flex becomes stiffer, as will be described later. For this reason, the golf shaft 1 may not have the adjustment stepped portion 13 depending on the flex. It should be noted that the adjustment stepped portion 13 may be configured not to be provided at all regardless of the flex.
  • the plurality of adjustment stepped portions 13 are positioned on the tip side with respect to the body portion 11 and have different outer diameters.
  • the adjustment stepped portion 13 has a stepped shape adjacent to the main body portion 11 as a whole and is continuous with the stepped shape of the main body portion 11 .
  • the adjustment stepped portion 13 gradually increases in outer diameter toward the base end side.
  • adjustment stepped portion 13 does not need to be adjacent to the main body portion 11 , and a tapered portion, stepped portion, or the like may be interposed between the adjustment stepped portion 13 and the main body portion 11 .
  • each adjustment stepped portion 13 is constant. However, the outer diameter of the adjustment stepped portion 13 may be gradually increased toward the base end side.
  • the multiple adjustment stepped portions 13 have the same axial length. However, the axial lengths of the plurality of adjustment stepped portions 13 can be varied according to the flex development.
  • the straight portion 15 is a portion with a constant outer diameter located on the distal end side with respect to the adjustment stepped portion 13 .
  • the straight portion 15 may be interposed between the tip portion 5 and the body portion 11 of the intermediate portion 9 when the adjustment stepped portion 13 is omitted.
  • the straight portion 15 of this embodiment is interposed between the tip portion 5 and the adjustment step portion 13 and has an outer diameter smaller than the smallest adjustment step portion 13 and larger than the tip portion 5 .
  • the outer diameter of the straight portion 15 is set larger as the flex becomes harder, as will be described later.
  • the straight portion 15 is adjacent to the adjustment step portion 13 , but a tapered portion, a step portion, or the like may be interposed between the adjustment step portion 13 and the straight portion 15 .
  • the tapered portion 16 is a tapered portion arranged between the straight portion 15 and the tip portion 5 and absorbs the difference in diameter between the straight portion 15 and the tip portion 5 .
  • the golf shaft 1 having such a configuration has a stiffness distribution in which the stiffness gradually increases from the distal end portion 5 to the proximal end portion 7 .
  • the gradual increase in stiffness means that in the stiffness distribution, the slope of the approximation straight line from the tip portion 5 to the base end portion 7, the slope of the line connecting the tip portion 5 and the base end portion 7, or the tip portion 5 It means that the average value of the slope of the line segment from to the base end portion 7 is positive.
  • the gradual increase in rigidity includes the case where the rigidity slightly decreases from the distal end portion 5 to the proximal end portion 7 .
  • the permissible reduction in rigidity is 10% or less of the difference in rigidity between the distal end portion 5 and the proximal end portion 7 in order to obtain a sufficiently low trajectory and low spin.
  • the amount of decrease refers to the difference in stiffness between the peaks on the distal side and the valleys on the proximal side that are adjacent on the stiffness distribution.
  • FIG. 2 shows the stiffness distribution of the golf shaft 1.
  • the golf shaft 1 has a length of 41 inches and a weight of 110 g, which is lighter than a general golf shaft of the same length.
  • the rigidity of the distal end portion 5 and the proximal end portion 7 is constant. is increasing gradually.
  • This rigidity distribution is determined by the stepped shape and thickness of the golf shaft 1.
  • the axial length of the base end portion 7, the number of adjustment steps 13, and the outer diameter of the straight portion 15 are set. adjusted by
  • the intermediate portion 9 has an intermediate point P where the slope changes.
  • the tilt here means the tilt on the distal end side and the tilt on the proximal end side with the middle point P as the center.
  • the intermediate point P means not only the point where the gradient of the stiffness distribution changes, but also the corresponding portion in the axial direction of the golf shaft 1 .
  • the slope of the tip side is the slope of the approximate straight line from the tip portion 5 to the intermediate point P, the slope of the line connecting the tip portion 5 and the intermediate point P, or the slope of the line segment from the tip portion 5 to the intermediate portion 9. It is the average value of the inclination and the like.
  • the slope of the base end side is the slope of the approximate straight line from the intermediate point P to the base end portion 7, the slope of the line connecting the intermediate point P and the base end portion 7, or the slope from the intermediate portion 9 to the base end portion 7. It is the average value of the slope of the line segment leading to.
  • the inclination on the distal side is greater than that on the proximal side. This can be adjusted by the difference in outer diameter and the difference in axial dimension between adjacent steps 17 of the stepped shape.
  • the difference in stiffness between the distal end 5 and the intermediate point P is 3.00 kgf ⁇ m 2 to 5.00 kgf ⁇ m 2
  • the stiffness between the intermediate point P and the proximal end 7 is difference is 2.00 kgf ⁇ m 2 or less.
  • the rigidity of the tip portion 5 is the rigidity at a position 50 mm from the tip. is possible.
  • the rigidity of the base end portion 7 refers to the rigidity of any portion of the base end portion 7 . However, if the rigidity of the base end portion 7 varies in the axial direction, the average value, maximum value, minimum value, or the like can be used.
  • the intermediate point P is preferably located within a range of 40% to 60% of the total length of the golf shaft 1 from the tip of the golf shaft 1 .
  • the rigidity at the intermediate point P is preferably 5.40 kgf ⁇ m 2 to 8.00 kgf ⁇ m 2 . More preferably, the rigidity of the distal end portion 5 is 2.20 kgf ⁇ m 2 or more, and the rigidity of the proximal end portion 7 is 9.00 kgf ⁇ m 2 or less. In this embodiment, the intermediate point P is located at 50% of the total length, and the rigidity of the intermediate point P is 6.06 kgf ⁇ m 2 .
  • the rigidity of the distal end portion 5 is 2.30 kgf ⁇ m 2 , and the rigidity of the proximal end portion 7 is 7.39 kgf ⁇ m 2 . Note that the position and rigidity of the intermediate point P, and the rigidity of the distal end portion 5 and the proximal end portion 7 can be applied to those other than those described above.
  • the rigidity is set so as not to exceed 4.00 kgf ⁇ m 2 from the tip to the position of 20% of the total length.
  • the golf shaft 1 of this embodiment Due to this rigidity distribution, in the golf shaft 1 of this embodiment, by increasing the rigidity of the distal end portion 5 and decreasing the rigidity of the proximal end portion 7 in relation to the intermediate point P, the bending becomes slow and the launch angle can be made smaller. In addition, the high rigidity of the midpoint P can reduce the spin amount. As a result, the golf shaft 1 of this embodiment can achieve a sufficiently low trajectory and low spin.
  • FIG. 3 is a chart showing the launch angle and spin rate of the golf shaft 1 of this example together with a comparative example
  • FIG. 4 is a graph showing the stiffness distribution of FIG. 2 along with the stiffness distribution of a comparative example. Only Comparative Example 3 has a length of 39 inches in order to match the count as a golf club with those of the Examples and other Comparative Examples.
  • Comparative Example 1 has low trajectory and non-low spin
  • Comparative Example 2 has high trajectory and low spin
  • Comparative Example 3 has both general trajectory and spin amount.
  • Comparative Example 1 has a higher rigidity at the distal end and a lower rigidity at the proximal end.
  • Comparative Example 2 has a higher rigidity over the entire region from the intermediate portion to the base end portion.
  • the rigidity is set high from the distal end portion to the intermediate portion, and the rigidity is set low from the intermediate portion to the proximal end portion, as compared with Comparative Example 3.
  • the stiffness of the intermediate portion 9 of this example is positioned between Comparative Examples 1 and 2.
  • the spin rate can be reduced while maintaining the same launch angle as compared to Comparative Example 1, in which the rigidity on the tip side is simply improved.
  • the spin amount is even smaller than that of Comparative Example 2, which has a low spin rate.
  • a plate material is rolled to form a tubular body having a constant inner and outer diameter. Stepped processing is performed on this tubular body, and the wall thickness is set.
  • the flex is adjusted by setting the axial length of the base end portion 7 , the number of the adjustment stepped portions 13 , and the outer diameter of the straight portion 15 .
  • FIG. 5 is a side view showing the basic shape for the method of manufacturing the golf shaft 1 of this embodiment.
  • the intermediate portion 9 has a main body portion 11 , a plurality of adjustment stepped portions 13 and a straight portion 15 .
  • the basic shape has three adjustment stepped portions 13, and the base end portion 7 is set shorter than the golf shaft 1 of FIG. 1 accordingly.
  • the basic shape does not have the tapered portion 16 .
  • Others are the same as the golf shaft 1 of FIG.
  • the number of adjustment stepped portions 13 and the dimensions of each portion can be changed according to the characteristics of the golf shaft 1 .
  • Flex adjustment is performed by extending the length of the base end portion 7 in the axial direction by one or more adjustment step portions 13 with respect to the basic shape, and adjusting steps corresponding to the amount of extension of the length of the base end portion 7 . This is done by eliminating the part 13 . Thereby, the flex can be adjusted without changing the rigidity distribution of the body portion 11 .
  • the outer diameter of the straight portion 15 is made the same as the largest outer diameter of the removed adjustment stepped portions 13 .
  • the rigidity of the distal end side is improved, and an increase in the gradient of the rigidity distribution from the distal end portion 5 to the intermediate point P is suppressed.
  • a tapered portion 16 is formed to absorb the difference in outer diameter between the tip portion 5 and the straight portion 5 .
  • the flex adjustment (manufacturing method) of this embodiment can be applied to golf shafts other than the golf shaft 1 for low trajectory and low spin. With other golf shafts, it may not be necessary to suppress the increase in the slope of the stiffness distribution from the tip portion 5 to the intermediate point P when adjusting the flex. In this case, the outer diameter of the straight portion 15 does not need to be varied when adjusting the flex, and the basic shape may remain unchanged.
  • FIGS. 6(A) to 6(D) show golf shafts 1 for low trajectory and low spin with different flexes.
  • the golf shafts 1 shown in FIGS. 6(A) to 6(D) have harder flexes in this order, and are R, S, X, and TX, respectively.
  • the golf shaft 1 of FIG. 6(A) has the same basic shape as that of FIG.
  • the golf shaft 1 shown in FIG. 6B is the same as the golf shaft 1 shown in FIG. 5, and does not have the adjustment stepped portion 13 having the smallest diameter with respect to the basic shape.
  • the golf shaft 1 shown in FIG. 6(C) does not have two adjustment stepped portions 13 from the smaller diameter side, and the golf shaft 1 shown in FIG. 6(D) does not have all the adjustment stepped portions 13. be.
  • the length of the base end portion 7 is extended in the axial direction by one, two, and three adjustment steps 13, respectively.
  • the outer diameter of the straight portion 15 is set to be the same as the outer diameters of the first, second, and third steps of the adjustment stepped portion 13, respectively. It is
  • the difference in the outer diameter between the straight portion 15 and the tip portion 5 increases due to this setting of the outer diameter. It is interposed between it and the tip portion 5 .
  • the tapered portion 16 is set longer in the axial direction as the difference in outer diameter between the straight portion 15 and the distal end portion 5 increases. This prevents the taper angle of the taper portion 16 from increasing.
  • FIGS. 7(A) and 7(B) show the stiffness at the distal end, midpoint and proximal end of the golf shaft 1 of FIGS. 6(A)-6(D) together with the corresponding stiffnesses of the comparative example, FIG. 7A is for 41 inches, and FIG. 7B is for 37 inches.
  • the golf shafts 1 of FIGS. 6A to 6D are indicated as R, S, X, and TX, respectively.
  • Mid-distal refers to the difference in stiffness between midpoint P and tip 5
  • proximal-mid refers to the difference in stiffness between proximal 7 and midpoint P.
  • FIG. The numerical values in FIG. 7 are in units of kgf ⁇ m 2 .
  • the golf shaft 1 of this embodiment has a middle-to-tip range of 3.00 to 5.00 kgf ⁇ m 2 and a base-to-center range of 2.00 kgf ⁇ m 2 or less.
  • Comparative Examples 1 and 2 could not simultaneously satisfy 3.00 to 5.00 kgf ⁇ m 2 between the middle and the tip and 2.00 kgf ⁇ m 2 or less between the base and the middle.
  • Comparative Examples 1 and 2 low trajectory and low spin as shown in FIG. 3 cannot be obtained.
  • the rigidity of the distal end portion 5 is increased and the rigidity of the proximal end portion 7 is decreased in relation to the intermediate point P, so that the launch angle can be reliably reduced. can reduce spin rate.
  • the golf shaft 1 of this embodiment can achieve a sufficiently low trajectory and low spin.
  • the distance from the tip of the golf shaft 1 to the middle point P is located in the range of 40% to 60% of the total length of the golf shaft 1, low trajectory and low spin can be obtained more reliably. can be done.
  • the golf shaft 1 has a stepped shape in which the outer diameter gradually increases between the distal end portion 5 and the proximal end portion 7 .
  • the difference in outer diameter between adjacent stepped portions 17 from the intermediate point P to the base end portion 7 is smaller than the difference in outer diameter between the two.
  • the length of the base end portion 7 is extended in the axial direction by one or more adjustment steps 13 with respect to the basic shape, and the length of the base end portion 7 is extended.
  • a golf shaft 1 having different flexes is manufactured by eliminating an adjustment step corresponding to the amount of extension.
  • flex deployment can be achieved without changing the rigidity distribution of the main body portion 11 .
  • the flex can be visually determined from the number of adjustment steps 13 of the manufactured golf shaft 1 . Furthermore, by setting the length and diameter of the adjustment stepped portion 13, it is possible to easily perform targeted flex development.
  • the outer diameter of the straight portion 15 is made the same as the largest outer diameter of the adjusting step portion 13 without the outer diameter. Therefore, in the golf shaft 1 with low trajectory and low spin, flex development can be easily performed.

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Abstract

Provided is a golf shaft with which it is possible to obtain a sufficiently-low trajectory and a low spin.　This invention has a rigidity distribution in which the rigidity increases gradually from a distal end section 5 to a base end section 7. In this rigidity distribution, an intermediate section 9, which is between the distal end section 5 and the base end section 7, includes an intermediate point P at which inclination changes. A difference in the rigidity between the distal end section 5 and the intermediate point P is 3.00 kgf· m2 to 5.00 kgf· m2, and a difference in the rigidity between the intermediate point P and the base end section 7 is 2.00 kgf· m2 or less.

Description

ゴルフシャフト及びその製造方法Golf shaft and manufacturing method thereof
　本発明は、低弾道且つ低スピンを実現するゴルフシャフト及びその製造方法に関する。 The present invention relates to a golf shaft that achieves low trajectory and low spin, and a method for manufacturing the same.
　ゴルフにおいては、高弾道且つ低スピンであることによってボールの飛距離が伸びることが知られている。こうした高弾道且つ低スピンのボールは、例えば特許文献１のように、ゴルフクラブのシャフト（ゴルフシャフト）の剛性分布を調整することで実現可能である。 In golf, it is known that high trajectory and low spin increase the flight distance of the ball. Such a ball with high trajectory and low spin can be realized by adjusting the rigidity distribution of the shaft of the golf club (golf shaft), as disclosed in Patent Document 1, for example.
　かかる高弾道且つ低スピンのボールは、風の影響を受けやすく、飛距離が伸びないことがある。この場合、より弾道を低くした低弾道且つ低スピンのボールとすることが有利である。 A ball with such a high trajectory and low spin is easily affected by the wind and may not travel a long distance. In this case, it is advantageous to use a ball with a low trajectory and low spin.
　この低弾道且つ低スピンのボールは、一般にゴルフシャフトの先端の剛性を向上すれば実現できるとされているが、単に先端の剛性を向上させるだけでは不十分であった。 It is generally said that this low trajectory and low spin ball can be achieved by improving the rigidity of the tip of a golf shaft, but simply improving the rigidity of the tip was not sufficient.
特開２０１４－３３８３１号JP 2014-33831
　解決しようとする問題点は、十分な低弾道且つ低スピンを得られなかった点である。 The problem we are trying to solve is that we were unable to obtain a sufficiently low trajectory and low spin.
　本発明は、先端部から基端部にわたって漸次剛性が増加する剛性分布を有し、剛性分布において、前記先端部及び前記基端部間の中間部に傾きが変わる中間点を有し、前記先端部と前記中間点との間の剛性の差が３．００ｋｇｆ・ｍ２～５．００ｋｇｆ・ｍ２であり、前記中間点と前記基端部との間の剛性の差が２．００ｋｇｆ・ｍ２以下であるゴルフシャフトを提供する。 The present invention has a stiffness distribution in which the stiffness gradually increases from the distal end portion to the proximal end portion, the stiffness distribution has an intermediate point where the slope changes in an intermediate portion between the distal end portion and the proximal end portion, and the distal end portion and the intermediate point is 3.00 kgf·m 2 to 5.00 kgf·m 2 , and the difference in stiffness between the intermediate point and the base end is 2.00 kgf·m 2 or less.
　また、本発明は、先端部から基端部にわたって漸次剛性が増加する剛性分布を有するゴルフシャフトの製造方法であって、前記先端部と前記基端部との間の中間部が、本体部と、該本体部に対して先端側に位置する外径の異なる複数の調整段部と、該調整段部に対して先端側に位置する外径が一定のストレート部とを有した基本形状に対し、一又は複数の調整段部の分だけ前記基端部の長さを軸方向に伸ばし、且つ前記基端部の長さの伸ばし量に対応する調整段部を無くすゴルフシャフトの製造方法を提供する。 The present invention also provides a method for manufacturing a golf shaft having a stiffness distribution in which the stiffness gradually increases from the distal end portion to the proximal end portion, wherein an intermediate portion between the distal end portion and the proximal end portion is a main body portion. , with respect to a basic shape having a plurality of adjusting stepped portions with different outer diameters located on the tip side with respect to the main body portion and a straight portion with a constant outer diameter located on the tip side with respect to the adjusting stepped portion A method for manufacturing a golf shaft, wherein the length of the proximal end is axially extended by one or more adjustment steps, and the adjustment steps corresponding to the amount of extension of the length of the proximal end are eliminated. do.
　本発明のゴルフシャフトでは、中間点との関係において先端部及び基端部の剛性を適切に設定し、十分な低弾道且つ低スピンを得ることができる。 With the golf shaft of the present invention, the rigidity of the tip end and the base end can be appropriately set in relation to the midpoint to obtain sufficiently low trajectory and low spin.
　本発明のゴルフシャフトの製造方法では、十分な低弾道且つ低スピンを得るゴルフシャフトを含め、先端部から基端部にわたって漸次剛性が増加するゴルフシャフトにおいて、複数のフレックスを容易に展開することができる。 In the golf shaft manufacturing method of the present invention, it is possible to easily develop a plurality of flexes in a golf shaft having a gradual increase in stiffness from the tip to the base, including a golf shaft that provides sufficiently low trajectory and low spin. can.
図１は、本発明の実施例１に係るゴルフシャフトの側面図である。FIG. 1 is a side view of a golf shaft according to Example 1 of the present invention. 図２は、図１のゴルフシャフトの剛性分布を示すグラフである。FIG. 2 is a graph showing the stiffness distribution of the golf shaft of FIG. 1; 図３は、図１のゴルフシャフトの打ち出し角度とスピン量を比較例と共に示す図表である。FIG. 3 is a chart showing the launch angle and spin amount of the golf shaft of FIG. 1 together with a comparative example. 図４は、図２の剛性分布を比較例の剛性分布と共に示すグラフである。FIG. 4 is a graph showing the stiffness distribution of FIG. 2 together with the stiffness distribution of a comparative example. 図５は、本発明の実施例１に係るゴルフシャフトの製造方法に用いられる基本形状のゴルフシャフトを示す側面図である。FIG. 5 is a side view showing a basic golf shaft used in the golf shaft manufacturing method according to the first embodiment of the present invention. 図６（Ａ）～（Ｄ）は、フレックスの異なるゴルフシャフトを示す側面図である。6A to 6D are side views showing golf shafts with different flexes. 図７（Ａ）及び（Ｂ）は、図６（Ａ）～（Ｄ）のゴルフシャフトの先端部、中間点、基端部の剛性を比較例の対応する剛性と共に示す図表である。FIGS. 7A and 7B are charts showing the stiffness of the tip, midpoint, and proximal ends of the golf shafts of FIGS. 6A-6D along with the corresponding stiffnesses of a comparative example.
　十分な低弾道且つ低スピンを得るという目的を、ゴルフシャフトの剛性分布によって実現した。 The goal of obtaining a sufficiently low trajectory and low spin was achieved through the rigidity distribution of the golf shaft.
　すなわち、ゴルフシャフト（１）は、先端部（５）から基端部（７）にわたって漸次剛性が増加する剛性分布を有する。この剛性分布において、先端部（５）及び基端部（７）間の中間部（９）に傾きが変わる中間点（Ｐ）を有し、先端部（５）と中間点（Ｐ）との間の剛性の差が３．００ｋｇｆ・ｍ２～５．００ｋｇｆ・ｍ２であり、中間点（Ｐ）と基端部（７）との間の剛性の差が２．００ｋｇｆ・ｍ２以下となっている。 That is, the golf shaft (1) has a stiffness distribution in which the stiffness gradually increases from the distal end (5) to the proximal end (7). In this stiffness distribution, there is an intermediate point (P) where the slope changes in the intermediate portion (9) between the distal end (5) and the proximal end (7), and is 3.00 kgf·m 2 to 5.00 kgf·m 2 , and the difference in stiffness between the intermediate point (P) and the base end ( 7 ) is 2.00 kgf·m 2 or less. It's becoming
　中間点（Ｐ）は、ゴルフシャフト（１）の先端からの距離が全長の４０％～６０％までの範囲に位置させてもよい。 The intermediate point (P) may be positioned within a range of 40% to 60% of the total length from the tip of the golf shaft (1).
　ゴルフシャフト（１）は、先端部（５）と基端部（７）との間で漸次外径が大きくなる段付き形状であり、この段付き形状は、先端部（５）から中間点（Ｐ）までの隣接する段部（１７）間の外径の差よりも中間点（Ｐ）から基端部（７）までの隣接する段部（１７）間の外径の差が小さい。 The golf shaft (1) has a stepped shape in which the outer diameter gradually increases between a distal end (5) and a proximal end (7). The difference in outer diameter between adjacent steps (17) from midpoint (P) to proximal end (7) is smaller than the difference in outer diameter between adjacent steps (17) to P).
　ゴルフシャフトの製造方法は、先端部（５）から基端部（７）にわたって漸次剛性が増加する剛性分布を有するゴルフシャフト（１）を製造する方法である。この製造方法は、先端部（５）と基端部（７）との間の中間部（９）が、本体部（１１）と、この本体部（１１）に対して先端側に位置する外径の異なる複数の調整段部（１３）と、この調整段部（１３）に対して先端側に位置する外径が一定のストレート部（１５）とを有した基本形状に対し、一又は複数の調整段部（１３）の分だけ基端部（７）の長さを軸方向に伸ばし、且つ基端部（７）の長さの伸ばし量に対応する調整段部（１３）を無くす。 The golf shaft manufacturing method is a method of manufacturing a golf shaft (1) having a stiffness distribution in which the stiffness gradually increases from the distal end (5) to the proximal end (7). In this manufacturing method, the intermediate portion (9) between the distal end portion (5) and the proximal end portion (7) includes a body portion (11) and an outer portion located distally with respect to the body portion (11). For a basic shape having a plurality of adjusting stepped portions (13) with different diameters and a straight portion (15) with a constant outer diameter located on the tip side of the adjusting stepped portion (13), one or more The length of the base end portion (7) is extended in the axial direction by the adjustment step portion (13) of , and the adjustment step portion (13) corresponding to the amount of extension of the length of the base end portion (7) is eliminated.
　この製造方法では、ストレート部（１５）の外径を、無くした調整段部（１３）の内の最も大きい外径と同一にしてもよい。 In this manufacturing method, the outer diameter of the straight portion (15) may be the same as the largest outer diameter of the removed adjustment stepped portions (13).
　　［ゴルフシャフトの構造］
　図１は、本発明の実施例１に係るゴルフシャフトの側面図である。 [Golf shaft structure]
FIG. 1 is a side view of a golf shaft according to Example 1 of the present invention.
　本実施例のゴルフシャフト１は、金属シャフトであり、金属製の中空管体からなる。このゴルフシャフト１は、全体として段付き形状の漸次増加する外径を有している。ゴルフシャフト１の横断面における断面形状は円形となっている。なお、ゴルフシャフト１の外径は、段付き形状ではなく、全体又は一部がテーパー状等のように他の形状であってもよい。また、ゴルフシャフト１の横断面形状は、楕円等の他の形状としてもよい。 The golf shaft 1 of this embodiment is a metal shaft, and consists of a metal hollow tubular body. The golf shaft 1 has a gradually increasing outer diameter with a generally stepped shape. The cross-sectional shape of the golf shaft 1 is circular. It should be noted that the outer diameter of the golf shaft 1 may be tapered in whole or in part, instead of the stepped shape. Moreover, the cross-sectional shape of the golf shaft 1 may be other shapes such as an ellipse.
　ゴルフシャフト１の長さは、３７～４１ｉｎｃｈ（約９３．９８～１０４．１４ｃｍ）となっている。ただし、ゴルフシャフト１は、３７ｉｎｃｈより短く、或いは４１ｉｎｃｈより長く設定することも可能である。また、ゴルフシャフト１の材質は、スチールであるが、他の材質であってもよい。他の材質としては、他の金属、例えばアルミニウムやチタン並びにそれらの合金、若しくはＣＦＲＰ等の非金属、或いは金属と非金属とを組み合わせたコンポジット材等がある。 The length of the golf shaft 1 is 37-41 inches (about 93.98-104.14 cm). However, the golf shaft 1 can be set shorter than 37 inches or longer than 41 inches. Further, the material of the golf shaft 1 is steel, but other materials may be used. Other materials include other metals such as aluminum, titanium and their alloys, non-metals such as CFRP, and composite materials in which metals and non-metals are combined.
　かかるゴルフシャフト１は、先端部５と、基端部７と、中間部９とで構成されている。 The golf shaft 1 is composed of a distal end portion 5 , a proximal end portion 7 and an intermediate portion 9 .
　先端部５は、軸方向の先端部であり、軸方向でのゴルフシャフト１の先端から所定範囲の領域をいう。本実施例の先端部５は、ゴルフクラブのヘッドが取り付けられる部分である。この先端部５は、ゴルフシャフト１の基端側へ向けて漸次僅かに外径が増加するテーパー状に形成されている。ただし、先端部５は、外径を一定にしたストレート状に形成してもよい。 The tip portion 5 is the tip portion in the axial direction, and refers to an area within a predetermined range from the tip of the golf shaft 1 in the axial direction. The tip portion 5 of this embodiment is a portion to which the head of the golf club is attached. The distal end portion 5 is tapered such that the outer diameter gradually increases toward the base end of the golf shaft 1 . However, the tip portion 5 may be formed in a straight shape with a constant outer diameter.
　基端部７は、ゴルフシャフト１の軸方向の基端部であり、軸方向でのゴルフシャフト１の基端から所定範囲の領域をいう。本実施例の基端部７は、ゴルフクラブのグリップが取り付けられる部分である。この基端部７は、外径を一定にしたストレート状に形成されているが、基端側へ向けて漸次僅かに外径が変化するテーパー状としてもよい。 The proximal end portion 7 is the proximal end portion of the golf shaft 1 in the axial direction, and refers to a region within a predetermined range from the proximal end of the golf shaft 1 in the axial direction. The base end portion 7 of this embodiment is a portion to which the grip of the golf club is attached. The base end portion 7 is formed in a straight shape with a constant outer diameter, but it may be tapered so that the outer diameter changes slightly toward the base end side.
　中間部９は、先端部５と基端部７との間に位置する部分であり、本体部１１と、複数の調整段部１３と、ストレート部１５と、テーパー部１６とで構成されている。 The intermediate portion 9 is a portion located between the distal end portion 5 and the proximal end portion 7, and is composed of a body portion 11, a plurality of adjustment stepped portions 13, a straight portion 15, and a tapered portion 16. .
　本体部１１は、全体として段付き形状に形成された部分であり、複数の段部１７によって構成されている。複数の段部１７は、基端側に向けて漸次外径が大きくなっている。各段部１７においては、外径が一定となっているが、外径を基端側に向けて漸次増加させてもよい。 The main body part 11 is a part formed in a stepped shape as a whole, and is composed of a plurality of stepped parts 17 . The outer diameters of the plurality of stepped portions 17 gradually increase toward the base end side. Each stepped portion 17 has a constant outer diameter, but the outer diameter may be gradually increased toward the base end side.
　本体部１１の段付き形状は、先端部５から後述する中間点Ｐ（図２参照）までの隣接する段部１７間の外径の差よりも中間点Ｐから基端部７までの隣接する段部１７間の外径の差が小さい。なお、中間点Ｐが段部１７の途中に位置する場合は、その段部１７と直前又は直後に位置する段部１７との外径の差から、それまでの段部１７間の外径の差よりも小さくすればよい。また、中間点Ｐから基端部７までの段部１７は、先端部５から中間点Ｐまでの段部１７よりも軸方向の寸法が長く設定されている。 The stepped shape of the main body portion 11 is such that the adjacent steps 17 from the intermediate point P to the base end 7 are closer to each other than the difference in outer diameter between the adjacent step portions 17 from the distal end 5 to the intermediate point P (see FIG. 2). A difference in outer diameter between the stepped portions 17 is small. When the intermediate point P is positioned in the middle of the stepped portion 17, the difference in the outer diameter between the stepped portion 17 and the stepped portion 17 positioned immediately before or after the stepped portion 17 determines the outer diameter of the stepped portion 17 up to that point. It should be smaller than the difference. Further, the stepped portion 17 from the intermediate point P to the base end portion 7 is set to be longer in the axial direction than the stepped portion 17 from the distal end portion 5 to the intermediate point P. As shown in FIG.
　この本体部１１は、ゴルフシャフト１のフレックスのバリエーションに拘わらず形状が変化しない部分である。ゴルフシャフト１のフレックスとは、ゴルフシャフト１の硬さのことであり、同一のゴルフシャフト１であっても、複数のバリエーションが展開されることが一般的である。 The body portion 11 is a portion whose shape does not change regardless of variations in the flex of the golf shaft 1 . The flex of the golf shaft 1 is the hardness of the golf shaft 1 , and even the same golf shaft 1 generally has a plurality of variations.
　複数の調整段部１３は、ゴルフシャフト１のフレックスを調整するための段部である。これら調整段部１３の数は、後述するようにフレックスが硬くなるに従って減少する。このため、フレックスによっては、ゴルフシャフト１が調整段部１３を有していないこともある。なお、調整段部１３は、フレックスに拘わらず、全く備えない構成とすることも可能である。 A plurality of adjustment stepped portions 13 are stepped portions for adjusting the flex of the golf shaft 1 . The number of these adjustment steps 13 decreases as the flex becomes stiffer, as will be described later. For this reason, the golf shaft 1 may not have the adjustment stepped portion 13 depending on the flex. It should be noted that the adjustment stepped portion 13 may be configured not to be provided at all regardless of the flex.
　複数の調整段部１３は、本体部１１に対して先端側に位置し、異なる外径を有する。本実施例において、調整段部１３は、全体として本体部１１に隣接する段付き形状であり、本体部１１の段付き形状に連続する。これら調整段部１３は、本体部１１の段部１７と同様に、基端側に向けて漸次外径が大きくなっている。 The plurality of adjustment stepped portions 13 are positioned on the tip side with respect to the body portion 11 and have different outer diameters. In this embodiment, the adjustment stepped portion 13 has a stepped shape adjacent to the main body portion 11 as a whole and is continuous with the stepped shape of the main body portion 11 . As with the stepped portion 17 of the main body portion 11, the adjustment stepped portion 13 gradually increases in outer diameter toward the base end side.
　なお、調整段部１３は、本体部１１に隣接する必要はなく、調整段部１３と本体部１１との間には、テーパー部や段部等を介在させてもよい。 Note that the adjustment stepped portion 13 does not need to be adjacent to the main body portion 11 , and a tapered portion, stepped portion, or the like may be interposed between the adjustment stepped portion 13 and the main body portion 11 .
　各調整段部１３の外径は、一定となっている。ただし、調整段部１３の外径は、基端側に向けて漸次増加させてもよい。複数の調整段部１３は、同一の軸方向の長さを有している。ただし、複数の調整段部１３の軸方向の長さは、フレックス展開に応じて異ならせることも可能である。 The outer diameter of each adjustment stepped portion 13 is constant. However, the outer diameter of the adjustment stepped portion 13 may be gradually increased toward the base end side. The multiple adjustment stepped portions 13 have the same axial length. However, the axial lengths of the plurality of adjustment stepped portions 13 can be varied according to the flex development.
　ストレート部１５は、調整段部１３に対して先端側に位置する外径が一定の部分である。なお、ストレート部１５は、調整段部１３が省略される場合、先端部５と中間部９の本体部１１との間に介設すればよい。 The straight portion 15 is a portion with a constant outer diameter located on the distal end side with respect to the adjustment stepped portion 13 . The straight portion 15 may be interposed between the tip portion 5 and the body portion 11 of the intermediate portion 9 when the adjustment stepped portion 13 is omitted.
　本実施例のストレート部１５は、先端部５と調整段部１３との間に介在し、外径が調整段部１３の最も小さいものよりも小さく、先端部５よりも大きい。このストレート部１５の外径は、後述するように、フレックスが硬くなるに従って大きく設定される。なお、ストレート部１５は、調整段部１３に隣接しているが、調整段部１３とストレート部１５との間には、テーパー部や段部等を介在させてもよい。 The straight portion 15 of this embodiment is interposed between the tip portion 5 and the adjustment step portion 13 and has an outer diameter smaller than the smallest adjustment step portion 13 and larger than the tip portion 5 . The outer diameter of the straight portion 15 is set larger as the flex becomes harder, as will be described later. The straight portion 15 is adjacent to the adjustment step portion 13 , but a tapered portion, a step portion, or the like may be interposed between the adjustment step portion 13 and the straight portion 15 .
　テーパー部１６は、ストレート部１５と先端部５との間に配置されたテーパー状の部分であり、ストレート部１５と先端部５との間の径の差を吸収する。 The tapered portion 16 is a tapered portion arranged between the straight portion 15 and the tip portion 5 and absorbs the difference in diameter between the straight portion 15 and the tip portion 5 .
　かかる構成のゴルフシャフト１は、先端部５から基端部７にわたって漸次剛性が増加する剛性分布を有している。なお、漸次剛性が増加するとは、剛性分布において、先端部５から基端部７に至る線分の近似直線の傾き、先端部５と基端部７とを結ぶ線の傾き、或いは先端部５から基端部７に至る線分の傾きの平均値等が正であることをいう。この限りにおいて、先端部５から基端部７に至るまでに剛性が僅かに下がるような場合も漸次剛性が増加するものに含まれる。 The golf shaft 1 having such a configuration has a stiffness distribution in which the stiffness gradually increases from the distal end portion 5 to the proximal end portion 7 . It should be noted that the gradual increase in stiffness means that in the stiffness distribution, the slope of the approximation straight line from the tip portion 5 to the base end portion 7, the slope of the line connecting the tip portion 5 and the base end portion 7, or the tip portion 5 It means that the average value of the slope of the line segment from to the base end portion 7 is positive. As far as this is concerned, the gradual increase in rigidity includes the case where the rigidity slightly decreases from the distal end portion 5 to the proximal end portion 7 .
　剛性が下がる場合において、許容される剛性の低下量は、十分な低弾道且つ低スピンを得るために、先端部５と基端部７との間の剛性の差の１０％以下とする。低下量とは、剛性分布上で隣接する先端側の山部と基端側の谷部との間の剛性の差をいう。 When the rigidity is reduced, the permissible reduction in rigidity is 10% or less of the difference in rigidity between the distal end portion 5 and the proximal end portion 7 in order to obtain a sufficiently low trajectory and low spin. The amount of decrease refers to the difference in stiffness between the peaks on the distal side and the valleys on the proximal side that are adjacent on the stiffness distribution.
　図２は、ゴルフシャフト１の剛性分布を示す。なお、図２では、ゴルフシャフト１の長さが４１ｉｎｃｈ、重量が１１０ｇとなっており、一般的な同一長さのゴルフシャフトよりも軽い。 2 shows the stiffness distribution of the golf shaft 1. FIG. In FIG. 2, the golf shaft 1 has a length of 41 inches and a weight of 110 g, which is lighter than a general golf shaft of the same length.
　図２の剛性分布のように、本実施例のゴルフシャフト１では、先端部５及び基端部７の剛性が一定となっており、先端部５から基端部７にわたる部分としての中間部９の剛性が漸次増加している。この剛性分布は、ゴルフシャフト１の段付き形状及び肉厚により設定され、後述するように基端部７の軸方向の長さ、調整段部１３の数、並びにストレート部１５の外径の設定により調整される。 As shown in the rigidity distribution in FIG. 2, in the golf shaft 1 of this embodiment, the rigidity of the distal end portion 5 and the proximal end portion 7 is constant. is increasing gradually. This rigidity distribution is determined by the stepped shape and thickness of the golf shaft 1. As will be described later, the axial length of the base end portion 7, the number of adjustment steps 13, and the outer diameter of the straight portion 15 are set. adjusted by
　かかる剛性分布において、中間部９は、傾きが変わる中間点Ｐを有している。ここでの傾きとは、中間点Ｐを中心とした先端側の傾きと基端側の傾きを意味する。なお、本明細書において、中間点Ｐは、剛性分布上の傾きが変わる点だけでなく、これに対応するゴルフシャフト１の軸方向での部位を意味する。 In this stiffness distribution, the intermediate portion 9 has an intermediate point P where the slope changes. The tilt here means the tilt on the distal end side and the tilt on the proximal end side with the middle point P as the center. In this specification, the intermediate point P means not only the point where the gradient of the stiffness distribution changes, but also the corresponding portion in the axial direction of the golf shaft 1 .
　先端側の傾きは、先端部５から中間点Ｐに至る線分の近似直線の傾き、先端部５と中間点Ｐとを結ぶ線の傾き、或いは先端部５から中間部９に至る線分の傾きの平均値等である。基端側の傾きは、中間点Ｐから基端部７に至る線分の近似直線の傾き、中間点Ｐと基端部７とを結ぶ線の傾き、或いは中間部９から基端部７に至る線分の傾きの平均値等である。 The slope of the tip side is the slope of the approximate straight line from the tip portion 5 to the intermediate point P, the slope of the line connecting the tip portion 5 and the intermediate point P, or the slope of the line segment from the tip portion 5 to the intermediate portion 9. It is the average value of the inclination and the like. The slope of the base end side is the slope of the approximate straight line from the intermediate point P to the base end portion 7, the slope of the line connecting the intermediate point P and the base end portion 7, or the slope from the intermediate portion 9 to the base end portion 7. It is the average value of the slope of the line segment leading to.
　先端側の傾きは、基端側の傾きよりも大きい。これは、段付き形状の隣接する段部１７間の外径の差及び軸方向の寸法の差により調整可能である。 The inclination on the distal side is greater than that on the proximal side. This can be adjusted by the difference in outer diameter and the difference in axial dimension between adjacent steps 17 of the stepped shape.
　かかる剛性分布において、先端部５と中間点Ｐとの間の剛性の差は、３．００ｋｇｆ・ｍ２～５．００ｋｇｆ・ｍ２であり、中間点Ｐと基端部７との間の剛性の差が２．００ｋｇｆ・ｍ２以下となっている。先端部５の剛性は、本実施例において、先端から５０ｍｍの位置の剛性であるが、先端部５の剛性が変動する場合は、先端部５の平均値、最大値、最小値等とすることが可能である。基端部７の剛性は、基端部７の何れかの部位における剛性をいう。ただし、基端部７の剛性が軸方向で変動する場合は、平均値、最大値、最小値等とすることが可能である。 In this stiffness distribution, the difference in stiffness between the distal end 5 and the intermediate point P is 3.00 kgf·m 2 to 5.00 kgf·m 2 , and the stiffness between the intermediate point P and the proximal end 7 is difference is 2.00 kgf·m 2 or less. In this embodiment, the rigidity of the tip portion 5 is the rigidity at a position 50 mm from the tip. is possible. The rigidity of the base end portion 7 refers to the rigidity of any portion of the base end portion 7 . However, if the rigidity of the base end portion 7 varies in the axial direction, the average value, maximum value, minimum value, or the like can be used.
　中間点Ｐは、好ましくはゴルフシャフト１の先端からの距離がゴルフシャフト１の全長の４０％～６０％までの範囲に位置する。中間点Ｐの剛性は、好ましくは５．４０ｋｇｆ・ｍ２～８．００ｋｇｆ・ｍ２とする。さらに好ましくは、先端部５の剛性は、２．２０ｋｇｆ・ｍ２以上、基端部７の剛性は、９．００ｋｇｆ・ｍ２以下とする。本実施例において、中間点Ｐの位置は、全長の５０％の位置であり、中間点Ｐの剛性は、６．０６ｋｇｆ・ｍ２となっている。先端部５の剛性は、２．３０ｋｇｆ・ｍ２、基端部７の剛性は、７．３９ｋｇｆ・ｍ２となっている。なお、中間点Ｐの位置及び剛性、先端部５及び基端部７の剛性は、上記以外も適用可能である。 The intermediate point P is preferably located within a range of 40% to 60% of the total length of the golf shaft 1 from the tip of the golf shaft 1 . The rigidity at the intermediate point P is preferably 5.40 kgf·m 2 to 8.00 kgf·m 2 . More preferably, the rigidity of the distal end portion 5 is 2.20 kgf·m 2 or more, and the rigidity of the proximal end portion 7 is 9.00 kgf·m 2 or less. In this embodiment, the intermediate point P is located at 50% of the total length, and the rigidity of the intermediate point P is 6.06 kgf·m 2 . The rigidity of the distal end portion 5 is 2.30 kgf·m 2 , and the rigidity of the proximal end portion 7 is 7.39 kgf·m 2 . Note that the position and rigidity of the intermediate point P, and the rigidity of the distal end portion 5 and the proximal end portion 7 can be applied to those other than those described above.
　また、本実施例では、先端から全長の２０％の位置に至るまでに、剛性が４．００ｋｇｆ・ｍ２を越えないように設定されている。 Further, in this embodiment, the rigidity is set so as not to exceed 4.00 kgf·m 2 from the tip to the position of 20% of the total length.
　この剛性分布により、本実施例のゴルフシャフト１では、中間点Ｐとの関係において、先端部５の剛性を高く且つ基端部７の剛性を低くすることで、しなりが遅くなり、打ち出し角度を小さくすることができる。また、中間点Ｐの剛性が高いことで、スピン量を減少させることができる。結果として、本実施例のゴルフシャフト１では、十分な低弾道且つ低スピンを得ることができる。 Due to this rigidity distribution, in the golf shaft 1 of this embodiment, by increasing the rigidity of the distal end portion 5 and decreasing the rigidity of the proximal end portion 7 in relation to the intermediate point P, the bending becomes slow and the launch angle can be made smaller. In addition, the high rigidity of the midpoint P can reduce the spin amount. As a result, the golf shaft 1 of this embodiment can achieve a sufficiently low trajectory and low spin.
　図３は、本実施例のゴルフシャフト１の打ち出し角度とスピン量を比較例と共に示す図表であり、図４は、図２の剛性分布を比較例の剛性分布と共に示すグラフである。なお、比較例３のみ、ゴルフクラブとしての番手を実施例及び他の比較例と合わせるために長さが３９インチとなっている。 FIG. 3 is a chart showing the launch angle and spin rate of the golf shaft 1 of this example together with a comparative example, and FIG. 4 is a graph showing the stiffness distribution of FIG. 2 along with the stiffness distribution of a comparative example. Only Comparative Example 3 has a length of 39 inches in order to match the count as a golf club with those of the Examples and other Comparative Examples.
　比較例１は、低弾道且つ非低スピン、比較例２は、高弾道且つ低スピン、比較例３は、弾道及びスピン量が共に一般的なものである。 Comparative Example 1 has low trajectory and non-low spin, Comparative Example 2 has high trajectory and low spin, and Comparative Example 3 has both general trajectory and spin amount.
　比較例１は、比較例３に対して先端部側の剛性が高く設定されると共に基端部の剛性が低く設定されている。比較例２は、比較例３に対して中間部から基端部にわたる全域で剛性が高く設定されている。 Compared to Comparative Example 3, Comparative Example 1 has a higher rigidity at the distal end and a lower rigidity at the proximal end. Compared to Comparative Example 3, Comparative Example 2 has a higher rigidity over the entire region from the intermediate portion to the base end portion.
　これに対し、本実施例では、比較例３に対し、先端部から中間部にかけて剛性が高く設定され、中間部から基端部にかけて剛性が低く設定されている。また、本実施例は、中間部９の剛性が、比較例１及び２間に位置する。 On the other hand, in this embodiment, the rigidity is set high from the distal end portion to the intermediate portion, and the rigidity is set low from the intermediate portion to the proximal end portion, as compared with Comparative Example 3. In addition, the stiffness of the intermediate portion 9 of this example is positioned between Comparative Examples 1 and 2. FIG.
　かかる相違より、本実施例では、単に先端部側の剛性を向上させた比較例１に対して、同等の打ち出し角度としながら、スピン量を少なくすることができている。また、スピン量については、低スピンの比較例２よりも更に少なくできている。 Due to this difference, in this example, the spin rate can be reduced while maintaining the same launch angle as compared to Comparative Example 1, in which the rigidity on the tip side is simply improved. In addition, the spin amount is even smaller than that of Comparative Example 2, which has a low spin rate.
　　［ゴルフシャフトの製造方法］
　本実施例のゴルフシャフト１の製造方法では、例えば板材を丸めて内外径が一定の管体を形成する。この管体に対し、段付け加工すると共に肉厚を設定する。 [Manufacturing method of golf shaft]
In the method of manufacturing the golf shaft 1 of this embodiment, for example, a plate material is rolled to form a tubular body having a constant inner and outer diameter. Stepped processing is performed on this tubular body, and the wall thickness is set.
　このとき、本実施例では、基端部７の軸方向の長さ、調整段部１３の数、並びにストレート部１５の外径の設定によってフレックスが調整される。 At this time, in this embodiment, the flex is adjusted by setting the axial length of the base end portion 7 , the number of the adjustment stepped portions 13 , and the outer diameter of the straight portion 15 .
　フレックスの調整は、図５の基本形状に対して行われる。図５は、本実施例のゴルフシャフト１の製造方法のための基本形状を示す側面図である。 Flex adjustment is performed on the basic shape in Fig. 5. FIG. 5 is a side view showing the basic shape for the method of manufacturing the golf shaft 1 of this embodiment.
　基本形状は、中間部９が、本体部１１、複数の調整段部１３、及びストレート部１５を有している。本実施例において、基本形状は、３つの調整段部１３を有し、その分、図１のゴルフシャフト１よりも基端部７が短く設定されている。また、基本形状は、テーパー部１６を有していない。その他は、図１のゴルフシャフト１と同一である。なお、基本形状において、調整段部１３の数や各部の寸法等はゴルフシャフト１の特性に応じて変更可能である。 As for the basic shape, the intermediate portion 9 has a main body portion 11 , a plurality of adjustment stepped portions 13 and a straight portion 15 . In this embodiment, the basic shape has three adjustment stepped portions 13, and the base end portion 7 is set shorter than the golf shaft 1 of FIG. 1 accordingly. Also, the basic shape does not have the tapered portion 16 . Others are the same as the golf shaft 1 of FIG. In the basic shape, the number of adjustment stepped portions 13 and the dimensions of each portion can be changed according to the characteristics of the golf shaft 1 .
　フレックスの調整は、基本形状に対し、一又は複数の調整段部１３の分だけ基端部７の長さを軸方向に伸ばし、且つ基端部７の長さの伸ばし量に対応する調整段部１３を無くすことで行われる。これにより、本体部１１の剛性分布を変更することなく、フレックスを調整することができる。 Flex adjustment is performed by extending the length of the base end portion 7 in the axial direction by one or more adjustment step portions 13 with respect to the basic shape, and adjusting steps corresponding to the amount of extension of the length of the base end portion 7 . This is done by eliminating the part 13 . Thereby, the flex can be adjusted without changing the rigidity distribution of the body portion 11 .
　さらに、ストレート部１５の外径を、無くした調整段部１３の内の最も大きい外径と同一にする。これにより、先端側の剛性を向上させて先端部５から中間点Ｐまでの剛性分布の傾きの上昇を抑制している。このとき、先端部５とストレート部５との外径の差を吸収するために、テーパー部１６が形成される。 Furthermore, the outer diameter of the straight portion 15 is made the same as the largest outer diameter of the removed adjustment stepped portions 13 . As a result, the rigidity of the distal end side is improved, and an increase in the gradient of the rigidity distribution from the distal end portion 5 to the intermediate point P is suppressed. At this time, a tapered portion 16 is formed to absorb the difference in outer diameter between the tip portion 5 and the straight portion 5 .
　なお、本実施例のフレックスの調整（製造方法）は、低弾道且つ低スピンのためのゴルフシャフト１以外の他のゴルフシャフトにも適用可能である。その他のゴルフシャフトでは、フレックス調整時に先端部５から中間点Ｐにわたる剛性分布の傾きの上昇を抑制しなくてもよいことがある。この場合、ストレート部１５の外径は、フレックスの調整時に変動させる必要はなく、基本形状のままとしてもよい。 It should be noted that the flex adjustment (manufacturing method) of this embodiment can be applied to golf shafts other than the golf shaft 1 for low trajectory and low spin. With other golf shafts, it may not be necessary to suppress the increase in the slope of the stiffness distribution from the tip portion 5 to the intermediate point P when adjusting the flex. In this case, the outer diameter of the straight portion 15 does not need to be varied when adjusting the flex, and the basic shape may remain unchanged.
　図６（Ａ）～図６（Ｄ）は、フレックスの異なる低弾道且つ低スピンのためのゴルフシャフト１を示す。図６（Ａ）～図６（Ｄ）のゴルフシャフト１は、この順序でフレックスが硬くなり、それぞれＲ、Ｓ、Ｘ、ＴＸとなっている。 FIGS. 6(A) to 6(D) show golf shafts 1 for low trajectory and low spin with different flexes. The golf shafts 1 shown in FIGS. 6(A) to 6(D) have harder flexes in this order, and are R, S, X, and TX, respectively.
　図６（Ａ）のゴルフシャフト１は、図５の基本形状と同一である。図６（Ｂ）のゴルフシャフト１は、図５のゴルフシャフト１と同一であり、基本形状に対して最も径の小さい調整段部１３を無くしたものである。図６（Ｃ）のゴルフシャフト１は、径の小さい方から調整段部１３を二つ無くしたものであり、図６（Ｄ）のゴルフシャフト１は、調整段部１３を全て無くしたものである。 The golf shaft 1 of FIG. 6(A) has the same basic shape as that of FIG. The golf shaft 1 shown in FIG. 6B is the same as the golf shaft 1 shown in FIG. 5, and does not have the adjustment stepped portion 13 having the smallest diameter with respect to the basic shape. The golf shaft 1 shown in FIG. 6(C) does not have two adjustment stepped portions 13 from the smaller diameter side, and the golf shaft 1 shown in FIG. 6(D) does not have all the adjustment stepped portions 13. be.
　図６（Ｂ）～図６（Ｄ）のゴルフシャフト１は、それぞれ調整段部１３の一つ、二つ、三つ分だけ、基端部７の長さを軸方向に伸ばしている。また、図６（Ｂ）～図６（Ｄ）のゴルフシャフト１は、ストレート部１５の外径が、それぞれ調整段部１３の一段目、二段目、三段目の外径と同一に設定されている。 In the golf shafts 1 shown in FIGS. 6(B) to 6(D), the length of the base end portion 7 is extended in the axial direction by one, two, and three adjustment steps 13, respectively. 6(B) to 6(D), the outer diameter of the straight portion 15 is set to be the same as the outer diameters of the first, second, and third steps of the adjustment stepped portion 13, respectively. It is
　この外径の設定により、図６（Ｂ）～図６（Ｄ）のゴルフシャフト１では、ストレート部１５と先端部５との外径の差が大きくなるため、テーパー部１６がストレート部１５と先端部５との間に介設されている。本実施例では、ストレート部１５と先端部５との外径の差が大きくなるほど、テーパー部１６が軸方向に長く設定されている。これにより、テーパー部１６のテーパー角度が大きくなることが抑制されている。 6(B) to 6(D), the difference in the outer diameter between the straight portion 15 and the tip portion 5 increases due to this setting of the outer diameter. It is interposed between it and the tip portion 5 . In this embodiment, the tapered portion 16 is set longer in the axial direction as the difference in outer diameter between the straight portion 15 and the distal end portion 5 increases. This prevents the taper angle of the taper portion 16 from increasing.
　図７（Ａ）及び図７（Ｂ）は、図６（Ａ）～図６（Ｄ）のゴルフシャフト１の先端部、中間点、基端部の剛性を比較例の対応する剛性と共に示し、図７（Ａ）は４１インチ、図７（Ｂ）は３７インチの場合である。図７において、図６（Ａ）～（Ｄ）のゴルフシャフト１は、それぞれＲ、Ｓ、Ｘ、ＴＸとして示している。中間－先端は、中間点Ｐと先端部５との間の剛性の差を示し、基端－中間は、基端部７と中間点Ｐとの間の剛性の差を示す。図７中の数値は、単位がｋｇｆ・ｍ２である。 FIGS. 7(A) and 7(B) show the stiffness at the distal end, midpoint and proximal end of the golf shaft 1 of FIGS. 6(A)-6(D) together with the corresponding stiffnesses of the comparative example, FIG. 7A is for 41 inches, and FIG. 7B is for 37 inches. In FIG. 7, the golf shafts 1 of FIGS. 6A to 6D are indicated as R, S, X, and TX, respectively. Mid-distal refers to the difference in stiffness between midpoint P and tip 5, and proximal-mid refers to the difference in stiffness between proximal 7 and midpoint P. FIG. The numerical values in FIG. 7 are in units of kgf·m 2 .
　図７のように、本実施例のゴルフシャフト１は、何れも中間－先端が３．００～５．００ｋｇｆ・ｍ２であり、且つ基端－中間が２．００ｋｇｆ・ｍ２以下にできている。これに対し、比較例１及び２は、中間－先端が３．００～５．００ｋｇｆ・ｍ２及び基端－中間が２．００ｋｇｆ・ｍ２以下を同時に満たすことはできていない。結果として、比較例１及び２では、図３のように低弾道且つ低スピンが得られないものとなっている。 As shown in FIG. 7, the golf shaft 1 of this embodiment has a middle-to-tip range of 3.00 to 5.00 kgf·m 2 and a base-to-center range of 2.00 kgf·m 2 or less. there is On the other hand, Comparative Examples 1 and 2 could not simultaneously satisfy 3.00 to 5.00 kgf·m 2 between the middle and the tip and 2.00 kgf·m 2 or less between the base and the middle. As a result, in Comparative Examples 1 and 2, low trajectory and low spin as shown in FIG. 3 cannot be obtained.
　　［実施例１の効果］
　以上説明したように、本実施例のゴルフシャフト１は、先端部５から基端部７にわたって漸次増加する剛性分布において、先端部５及び基端部７間の中間部９に傾きが変わる中間点Ｐを有し、先端部５と中間部９の中間点Ｐとの間の剛性の差が３．００ｋｇｆ・ｍ２～５．００ｋｇｆ・ｍ２であり、中間部９の中間点Ｐと基端部７との間の剛性の差が２．００ｋｇｆ・ｍ２以下である。 [Effect of Example 1]
As described above, in the golf shaft 1 of the present embodiment, in the stiffness distribution that gradually increases from the distal end portion 5 to the proximal end portion 7, the inclination changes to the intermediate portion 9 between the distal end portion 5 and the proximal end portion 7. P, the difference in rigidity between the distal end portion 5 and the intermediate point P of the intermediate portion 9 is 3.00 kgf·m 2 to 5.00 kgf·m 2 , and the intermediate point P of the intermediate portion 9 and the proximal end The difference in rigidity from the portion 7 is 2.00 kgf·m 2 or less.
　このため、本実施例のゴルフシャフト１では、中間点Ｐとの関係において、先端部５の剛性を高く且つ基端部７の剛性を低くすることで、確実に打ち出し角度を小さくし、且つ確実にスピン量を減少させることができる。結果として、本実施例のゴルフシャフト１では、十分な低弾道且つ低スピンを得ることができる。 For this reason, in the golf shaft 1 of the present embodiment, the rigidity of the distal end portion 5 is increased and the rigidity of the proximal end portion 7 is decreased in relation to the intermediate point P, so that the launch angle can be reliably reduced. can reduce spin rate. As a result, the golf shaft 1 of this embodiment can achieve a sufficiently low trajectory and low spin.
　また、ゴルフシャフト１では、中間点Ｐがゴルフシャフト１の先端からの距離がゴルフシャフト１の全長の４０％～６０％までの範囲に位置するので、より確実に低弾道且つ低スピンを得ることができる。 In addition, in the golf shaft 1, since the distance from the tip of the golf shaft 1 to the middle point P is located in the range of 40% to 60% of the total length of the golf shaft 1, low trajectory and low spin can be obtained more reliably. can be done.
　ゴルフシャフト１は、先端部５と基端部７との間で漸次外径が大きくなる段付き形状であり、この段付き形状は、先端部５から中間点Ｐまでの隣接する段部１７間の外径の差よりも中間点Ｐから基端部７までの隣接する段部１７間の外径の差が小さい。 The golf shaft 1 has a stepped shape in which the outer diameter gradually increases between the distal end portion 5 and the proximal end portion 7 . The difference in outer diameter between adjacent stepped portions 17 from the intermediate point P to the base end portion 7 is smaller than the difference in outer diameter between the two.
　このため、容易且つ確実に低弾道且つ低スピンを実現可能なゴルフシャフト１を得ることができる。 Therefore, it is possible to easily and reliably obtain the golf shaft 1 capable of realizing low trajectory and low spin.
　本実施例のゴルフシャフト１の製造方法は、基本形状に対し、一又は複数の調整段部１３の分だけ基端部７の長さを軸方向に伸ばし、且つ基端部７の長さの伸ばし量に対応する調整段部を無くすことで、フレックスの異なるゴルフシャフト１を製造する。 In the method of manufacturing the golf shaft 1 of this embodiment, the length of the base end portion 7 is extended in the axial direction by one or more adjustment steps 13 with respect to the basic shape, and the length of the base end portion 7 is extended. A golf shaft 1 having different flexes is manufactured by eliminating an adjustment step corresponding to the amount of extension.
　これにより、本実施例では、本体部１１の剛性分布を変更することなく、フレックス展開することができる。また、本実施例では、製造されたゴルフシャフト１の調整段部１３の数によりフレックスを外観上から判別することができる。さらに、調整段部１３の長さ及び径の設定により、狙ったフレックス展開を容易に行うことができる。 Accordingly, in this embodiment, flex deployment can be achieved without changing the rigidity distribution of the main body portion 11 . In addition, in this embodiment, the flex can be visually determined from the number of adjustment steps 13 of the manufactured golf shaft 1 . Furthermore, by setting the length and diameter of the adjustment stepped portion 13, it is possible to easily perform targeted flex development.
　また、本実施例では、ストレート部１５の外径を無くした調整段部１３の内の最も大きい外径と同一にする。従って、低弾道且つ低スピンのゴルフシャフト１において、フレックス展開を容易に行うことができる。 In addition, in this embodiment, the outer diameter of the straight portion 15 is made the same as the largest outer diameter of the adjusting step portion 13 without the outer diameter. Therefore, in the golf shaft 1 with low trajectory and low spin, flex development can be easily performed.
１　ゴルフシャフト
５　先端部
７　基端部
９　中間部
１１　本体部
１３　調整段部
１５　ストレート部
Ｐ　中間点  1 Golf shaft 5 Tip portion 7 Base end portion 9 Intermediate portion 11 Body portion 13 Adjustment stepped portion 15 Straight portion P Intermediate point

Claims (5)

  1. 　先端部から基端部にわたって漸次剛性が増加する剛性分布を有し、
    　前記剛性分布において、前記先端部及び前記基端部間の中間部に傾きが変わる中間点を有し、前記先端部と前記中間点との間の剛性の差が３．００ｋｇｆ・ｍ２～５．００ｋｇｆ・ｍ２であり、前記中間点と前記基端部との間の剛性の差が２．００ｋｇｆ・ｍ２以下である、
    　ゴルフシャフト。     Having a stiffness distribution in which the stiffness gradually increases from the distal end to the proximal end,
    The stiffness distribution has an intermediate point where the inclination changes in an intermediate portion between the distal end portion and the proximal end portion, and the difference in stiffness between the distal end portion and the intermediate point is 3.00 kgf·m 2 to 5. .00 kgf·m 2 , and the difference in stiffness between the intermediate point and the base end is 2.00 kgf·m 2 or less.
    golf shaft.
  2. 　請求項１記載のゴルフシャフトであって、
    　前記中間点は、先端からの距離が全長の４０％～６０％までの範囲に位置する、
    　ゴルフシャフト。     A golf shaft according to claim 1,
    The intermediate point is located in a range of 40% to 60% of the total length from the tip,
    golf shaft.
  3. 　請求項１又は２記載のゴルフシャフトであって、
    　前記先端部と前記基端部との間で漸次外径が大きくなる段付き形状であり、
    　前記段付き形状は、前記先端部から前記中間点までの隣接する段部間の外径の差よりも前記中間点から前記基端部までの隣接する段部間の外径の差が小さい、
    　ゴルフシャフト。     3. The golf shaft according to claim 1 or 2,
    a stepped shape in which the outer diameter gradually increases between the distal end portion and the proximal end portion;
    In the stepped shape, the difference in outer diameter between adjacent steps from the intermediate point to the base end is smaller than the difference in outer diameter between adjacent steps from the distal end to the intermediate point.
    golf shaft.
  4. 　先端部から基端部にわたって漸次剛性が増加する剛性分布を有するゴルフシャフトの製造方法であって、
    　前記先端部と前記基端部との間の中間部が、本体部と、該本体部に対して先端側に位置する外径の異なる複数の調整段部と、該調整段部に対して先端側に位置する外径が一定のストレート部とを有した基本形状に対し、一又は複数の調整段部の分だけ前記基端部の長さを軸方向に伸ばし、且つ前記基端部の長さの伸ばし量に対応する調整段部を無くす、
    　ゴルフシャフトの製造方法。     A method for manufacturing a golf shaft having a stiffness distribution in which the stiffness gradually increases from the distal end to the proximal end, comprising:
    An intermediate portion between the distal end portion and the proximal end portion includes a main body portion, a plurality of adjustment stepped portions having different outer diameters located on the distal side with respect to the main body portion, and a distal end with respect to the adjustment stepped portion. With respect to a basic shape having a straight portion with a constant outer diameter located on the side, the length of the base end is extended in the axial direction by one or more adjustment step portions, and the length of the base end is Eliminate the adjustment step corresponding to the amount of lengthening,
    A method of manufacturing a golf shaft.
  5. 　請求項４記載のゴルフシャフトの製造方法であって、
    　前記ストレート部の外径を、前記無くした調整段部の内の最も大きい外径と同一にする、
    　ゴルフシャフトの製造方法。     A method for manufacturing a golf shaft according to claim 4,
    making the outer diameter of the straight portion the same as the largest outer diameter of the lost adjustment stepped portions;
    A method of manufacturing a golf shaft.
PCT/JP2022/008647 2021-07-13 2022-03-01 Golf shaft and manufacturing method for same WO2023286324A1 (en)

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JP2007117109A (en) * 2005-10-24 2007-05-17 Sri Sports Ltd Golf club shaft
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JP2011212284A (en) * 2010-03-31 2011-10-27 Globeride Inc Golf club shaft set
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JP3033320U (en) * 1995-07-06 1997-01-21 ソマール株式会社 Golf club
JPH105380A (en) * 1996-06-20 1998-01-13 Daiwa Seiko Inc Golf club shaft
JPH10127838A (en) * 1996-10-30 1998-05-19 Daiwa Seiko Inc Golf club shaft
JP2005152613A (en) * 2003-10-28 2005-06-16 Sumitomo Rubber Ind Ltd Golf club shaft
JP2007117109A (en) * 2005-10-24 2007-05-17 Sri Sports Ltd Golf club shaft
JP2011092319A (en) * 2009-10-28 2011-05-12 Yamaha Corp Golf club shaft
JP2011212284A (en) * 2010-03-31 2011-10-27 Globeride Inc Golf club shaft set
JP2013116209A (en) * 2011-12-02 2013-06-13 Bridgestone Sports Co Ltd Golf club shaft
JP2014033831A (en) * 2012-08-09 2014-02-24 Nhk Spring Co Ltd Golf shaft
US20170065860A1 (en) * 2015-03-19 2017-03-09 Karsten Manufacturing Corporation Ascending weight iron shaft system

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EP4371630A1 (en) 2024-05-22
JP7142274B1 (en) 2022-09-27

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