WO2011121650A1

WO2011121650A1 - Golf club shaft and golf club

Info

Publication number: WO2011121650A1
Application number: PCT/JP2010/002331
Authority: WO
Inventors: 鵜野澤晶
Original assignee: マミヤ・オーピー株式会社
Priority date: 2010-03-30
Filing date: 2010-03-30
Publication date: 2011-10-06

Abstract

The golf club shaft (2) of a golf club (1) is provided with a main shaft (5) and an auxiliary shaft (6) inserted into the hollow section (5a) of the main shaft (5). The auxiliary shaft (6) is inserted into the hollow section (5a) in the tip side of the main shaft (5) through a shaft insertion hole (8) opening in the sole surface (3a) of the golf club head (3) and screwed and fixed into the shaft insertion hole (8) in an attachable and detachable manner. By replacing the auxiliary shaft (6) with another auxiliary shaft (6) different in bending rigidity, the bending rigidity of the golf club shaft (2) as the whole is changed. Accordingly, by mounting the auxiliary shaft (6) selected from among a plurality of types of auxiliary shafts to the main shaft (5), the bending rigidity of the golf club (1) can be adjusted easily.

Description

Golf club shaft and golf club

The present invention relates to a golf club shaft capable of adjusting bending rigidity and a golf club using the golf club shaft.

In the golf club market, there is a high demand for golf clubs with characteristics that fit various golfers' swing styles and preferences. For this purpose, for example, a golf club head and a golf club shaft that can be separated and a combination of a head and a shaft having different characteristics can be arbitrarily selected has been proposed. In addition, a golf club head has been proposed in which a head weight and a head balance can be adjusted by exchanging a weight removably attached to the head. Further, as described in

Patent Documents

1 and 2, for golf club shafts, golf club shafts having characteristics in which bending rigidity changes according to swing speed have been proposed.

Japanese Patent Laid-Open No. 07-163690 JP 07-185051 A

Here, it is desirable that the golf club shaft can be easily changed or adjusted in bending rigidity (deflection) according to the golfer's body shape, swing style, and preferences. However, at present, no attention is paid to making it possible to easily change or adjust the bending rigidity of the golf club shaft.

In view of this point, an object of the present invention is to propose a golf club shaft having a mechanism capable of easily changing or adjusting the bending rigidity, and a golf club having the golf club shaft.

In order to solve the above problems, the golf club shaft of the present invention is:
A main shaft,
An auxiliary shaft used to adjust the bending rigidity of the main shaft;
A hollow portion for inserting an auxiliary shaft formed coaxially with the main shaft inside the main shaft;
In order to insert the auxiliary shaft into the hollow portion, it has an insertion opening formed on the front end surface on the club head side of the main shaft or the rear end surface on the grip side,
The auxiliary shaft inserted into the hollow portion is detachably connected and fixed to the main shaft,
At least a part of the outer peripheral surface of the auxiliary shaft inserted into the hollow portion is mechanically engaged with the inner peripheral surface of the hollow portion.

In the golf club shaft of the present invention, an auxiliary shaft is inserted in a removable state in the hollow portion of the main shaft. Since the auxiliary shaft is mechanically engaged with the main shaft, the bending rigidity of the main shaft is enhanced by the auxiliary shaft. The bending rigidity of the entire golf club shaft can be lowered by removing the auxiliary shaft, and the bending rigidity of the entire golf club shaft can be further increased by attaching an auxiliary shaft having a high bending rigidity.

For example, multiple types of auxiliary shafts having different bending rigidity or different mechanical engagement ranges with the main shaft are prepared. An auxiliary shaft selected from these auxiliary shafts is attached to the main shaft. As a result, the bending rigidity of the golf club shaft can be adjusted to fit the golfer's desire. Therefore, it is possible to provide a golf club that can meet various requirements of golfers without exchanging the entire golf club shaft.

In the golf club shaft of the present invention, the auxiliary shaft is formed so as to cover at least a part of a shaft main body portion and a surface portion of the shaft main body portion facing the inner peripheral surface of the hollow portion of the main shaft. The covering layer is formed of a material having a lower surface hardness than the shaft main body portion.

ガ By providing a coating layer between the auxiliary shaft and the main shaft, it is possible to suppress backlash between them. In addition, when the auxiliary shaft is made of carbon fiber reinforced plastic, there is an advantage that the coating layer can prevent cracks and tears that are weak points of the carbon fiber reinforced plastic.

Next, the golf club of the present invention has the golf club shaft and a golf club head fixed to the tip thereof, so that the auxiliary shaft can be inserted from the sole surface side of the golf club head. ing. That is, in the golf club of the present invention, the insertion opening is formed in the tip surface of the main shaft, and the golf club head is inserted for insertion of an auxiliary shaft extending coaxially with the main shaft. A hole is formed, one end of the insertion hole is open to the sole surface of the club head, the other end communicates with the insertion opening of the main shaft, and the auxiliary shaft is connected to the club The head is inserted into the hollow portion from the sole surface side.

In this case, a part of the auxiliary shaft can be used as a weight for adjusting the head weight. In other words, the auxiliary shaft includes a weight portion for adjusting the head weight, which is positioned in the insertion hole of the golf club head in a state where the auxiliary shaft is inserted into the hollow portion of the main shaft.

Here, the golf club shaft of the present invention can also be used for a golf club having a structure in which a golf club head is detachable. In other words, the golf club of the present invention has the golf club shaft having the above-described configuration and a golf club head that is detachably fixed to the tip of the golf club shaft, and the insertion opening is formed on the main shaft. It is formed in the said front end surface.

In this case, the auxiliary shaft can be attached using a head fixing bracket used for connecting and fixing the golf club head and the main shaft. For this purpose, the golf club of the present invention has a head fixing bracket for connecting and fixing the golf club head to the tip of the main shaft in a detachable state, and the auxiliary shaft is attached to the head fixing bracket. It is characterized by being connected and fixed in a coaxial state and fixed to the main shaft via the head fixing bracket.

In this case, in order to mount the head fixing bracket from the sole surface side of the golf club head, in the present invention, the golf club head is formed with an insertion hole for inserting the head fixing bracket extending coaxially with the main shaft. One end of the insertion hole is open to the sole surface of the club head, the other end communicates with the insertion opening of the main shaft, and the auxiliary shaft is connected to the head fixing bracket together with the head fixing bracket. The golf club head is inserted into the hollow portion from the sole surface side.

Also in this case, the portion of the auxiliary shaft located in the golf club head can be used as a weight for adjusting the head weight.

Next, by inserting a part of the auxiliary shaft between the removable main shaft and the golf club head, the auxiliary shaft can be fixed to them.

In this case, it is desirable to interpose an elastic member between the main shaft and the auxiliary shaft, or between the golf club head and the auxiliary shaft. The looseness between these three members can be prevented or suppressed by the elastic member.

The golf club shaft of the present invention has an auxiliary shaft attached to the main shaft in a detachable manner, and at least a part of the main shaft and the auxiliary shaft are mechanically engaged. The bending rigidity of the golf club shaft can be easily adjusted by preparing a plurality of types of auxiliary shafts having different bending rigidity, engagement state with the main shaft, and the like, and selecting an auxiliary shaft to be attached to the main shaft. Therefore, it is possible to realize a golf club capable of adjusting the bending rigidity without replacing the entire golf club shaft. In addition, a golf club having the bending rigidity desired by the golfer can be provided at a low price.

1 is an overall view showing a golf club according to Embodiment 1 of the present invention. (A) is a schematic sectional drawing shown in the state which decomposed | disassembled the component of the principal part of the golf club of FIG. 1, (b) is a schematic sectional drawing shown in the state which assembled | attached the component. (A) is a schematic sectional drawing shown in the state which decomposed | disassembled the component of the principal part of a golf club, (b) is a schematic sectional drawing shown in the state which assembled | attached the component. It is explanatory drawing which shows each example of the auxiliary shaft of FIG. It is explanatory drawing which shows the example of a shape of a main shaft and an auxiliary shaft.

Embodiments of a golf club to which the present invention is applied will be described below with reference to the drawings.

(Embodiment 1)
1 is a perspective view showing a golf club according to Embodiment 1. FIG. The golf club 1 is, for example, a driver, and is a replaceable type in which the golf club head is removable from the golf club shaft. The golf club 1 includes a cylindrical golf club shaft 2, a golf club head 3 fixed to the tip, and a grip 4 attached to the outer periphery of the rear end portion of the golf club shaft 2. .

The golf club shaft 2 is composed of a cylindrical main shaft 5 and a cylindrical auxiliary shaft 6 inserted in a removable state inside the tip side of the main shaft 5. For example, as the auxiliary shaft 6, a plurality of types having different bending rigidity, a plurality of types having different lengths, and the like are prepared. By attaching the auxiliary shaft 6 selected from these to the main shaft 5, the bending rigidity of the golf club shaft 2 can be adjusted.

FIG. 2 shows a connecting and fixing portion of the golf club shaft 2 and the golf club head 3, (a) is a schematic cross-sectional view of the components separated, and (b) is a state of combining the components. It is a schematic sectional drawing. Referring to these drawings, a cylindrical hosel portion for connecting and fixing the golf club head 3 to the tip portion (the end portion opposite to the grip 4) of the main shaft 5 in the golf club shaft 2 is described. 7 is connected and fixed coaxially by an adhesive or the like. On the golf club head 3 side, a shaft insertion hole 8 having a circular cross section into which the hosel portion 7 can be inserted is formed. The shaft mounting hole 8 penetrates to the sole surface 3 a of the golf club head 3.

The auxiliary shaft 6 is a shaft having a circular cross section, and has an outer diameter dimension that can be inserted into the hollow portion 5a of the main shaft 5 from the insertion opening 5c side on the head side. A head fixing screw 9 is connected and fixed to one end 6a of the auxiliary shaft 6 by an adhesive or the like in a coaxial state. The head fixing screw 9 includes a large-diameter head portion 9a and a small-diameter cylindrical leg portion 9b extending coaxially from the head portion 9a. The auxiliary shaft 6 is coaxially inserted from the side and connected and fixed by an adhesive or the like. A male screw portion 9c is formed on the outer peripheral surface portion of the distal end portion of the leg portion 9b over a predetermined range from the distal end in the axial direction.

The front end 7 a of the hosel portion 7 of the main shaft 5 protrudes by a predetermined length from the insertion opening 5 c of the main shaft 5. A female screw portion 7b is formed on the circular inner peripheral surface of the tip portion 7a. A male screw portion 9c of the head fixing screw 9 can be screwed and fixed to the female screw portion 7b. The shaft insertion hole 8 on the golf club head 3 side includes a circular hole portion 8c having a constant inner diameter extending from the front end opening 8a to a position near the rear end opening 8b on the sole surface 3a side. The subsequent hole portion exposed on the sole surface 3a is a large-diameter hole portion 8d having a predetermined depth that is slightly larger in inner diameter.

In the golf club 1 having this configuration, the hosel portion 7 of the main shaft 5 is inserted from the tip opening 8 a of the shaft insertion hole 8 of the golf club head 3. Further, the auxiliary shaft 6 is inserted from the tip end of the shaft insertion hole 8 exposed on the sole surface 3a of the golf club head 3 from the front end thereof, and the auxiliary shaft 6 is inserted into the hollow portion of the main shaft 5. Plug into 5a. Then, the head fixing screw 9 attached to the auxiliary shaft 6 is turned to screw and fix the male screw portion 9c of the leg portion 9b to the female screw portion 7b on the hosel portion 7 side. As a result, as shown in FIG. 2B, the head portion 9a of the head fixing screw 9 abuts on the annular step surface 8e between the large-diameter hole portion 8d and the circular hole portion 8c in the shaft insertion hole 8, The golf club head 3 and the golf club shaft 2 are fastened and fixed. In this state, the auxiliary shaft 6 is brought into close contact with the inner peripheral surface of the main shaft 5, and a state in which these

shafts

5 and 6 are mechanically engaged is formed.

As described above, in the golf club shaft 2, the auxiliary shaft 6 is inserted into the hollow portion 5a of the main shaft 5 in a detachable state. Since the auxiliary shaft 6 is mechanically engaged with the main shaft 5, the bending rigidity of the main shaft 5 is enhanced by the auxiliary shaft 6. That is, the bending rigidity of the golf club shaft 2 as a whole is increased. By removing the auxiliary shaft 6, the bending rigidity of the golf club shaft 2 can be lowered. Further, by attaching a high bending rigidity member as the auxiliary shaft 6, the bending rigidity of the golf club shaft 2 can be made higher.

For example, as the auxiliary shaft 6, a plurality of types having the same length and different bending rigidity, different lengths and different mechanical engagement ranges with the main shaft 5 are prepared. An auxiliary shaft to be attached to the main shaft 5 is selected from these auxiliary shafts 6. Thereby, the bending rigidity of the golf club shaft 2 can be easily adjusted to fit the golfer's desire. Therefore, it is possible to realize the golf club 1 that can meet various requirements of golfers without exchanging the entire golf club shaft 2.

Here, one or both of the auxiliary shaft 6 and the inner peripheral surface portion of the main shaft 5 with which the auxiliary shaft 6 abuts can be formed of a carbon fiber-containing material, for example, a carbon fiber reinforced plastic. Except in special cases, the wear resistance of a carbon fiber reinforced plastic is generally much higher than that of the base plastic material. In addition, the coefficient of friction between carbon fiber reinforced plastics is considerably lower than that of plastic materials. In addition, the higher the carbon fiber is, the lower the coefficient of friction.

Therefore, when both or one of the auxiliary shaft 6 and the inner peripheral surface portion of the main shaft 5 in contact with the auxiliary shaft 6 is formed using a carbon fiber-containing material, the carbon fiber content rate is increased. It is desirable to reduce the frictional resistance. For example, when a prepreg material is used, it is desirable to use a carbon fiber content of 67% by weight or more. In addition, it is desirable to use a higher elastic material as the contained carbon fiber material because the frictional resistance of the contact portion can be lowered. For example, it is desirable to have an elastic modulus of about 24 t (tf / mm ² ) or more.

Also, it is desirable that the auxiliary shaft 6 is formed of a material having a lower surface hardness than the main shaft 5. Thereby, backlash between the auxiliary shaft 6 and the main shaft 5 can be prevented. For example, it is desirable to form the auxiliary shaft 6 from a material whose surface hardness is R120 or less in terms of Rockwell hardness.

Next, the head 9 a of the head fixing screw 9 connected and fixed to the tip of the auxiliary shaft 6 is located on the sole surface 3 a side of the golf club head 3. It is also possible to use the head 9a as a weight for adjusting the head weight. For example, an auxiliary shaft 6 to which a head fixing screw 9 having different weight heads 9a is connected and fixed is prepared. The auxiliary shaft 6 having an appropriate weight may be selected and used from them.

In addition, the golf club 1 of this example is a replaceable type in which the golf club head 3 and the golf club shaft 2 can be attached and detached. The present invention can be similarly applied to a golf club in which the golf club head 3 and the golf club shaft 2 are connected in a non-detachable state. For example, in FIG. 2, when the main shaft 5 is integrated with the golf club head 3 via the hosel portion 7, the auxiliary shaft 6 having a fixing screw similar to the head fixing screw 9 is connected to the sole surface 3a side. From the main shaft 5 side or the golf club head 3 side.

(Embodiment 2)
FIG. 3 shows a main part of the golf club according to the second embodiment, wherein (a) is a schematic cross-sectional view showing a state where components are disassembled, and (b) is a schematic cross-sectional view showing a state where components are connected. It is. The golf club 11 is connected and fixed so that the golf club head 13 can be removed by a head fixing nut 19 with respect to the golf club shaft 12. The golf club shaft 12 includes a cylindrical main shaft 15 and an auxiliary shaft 16 inserted into the hollow portion 15a on the distal end side.

A cylindrical hosel portion 17 for connecting and fixing the golf club head 13 is connected and fixed coaxially with an adhesive or the like at the tip end portion (the end portion opposite to the grip) of the main shaft 15. The front end opening of the main shaft 15 is an insertion opening 15 c for inserting the auxiliary shaft 16. The hosel portion 17 includes a cylindrical portion 17a having a constant outer diameter that is inserted into the golf club head 13 side. A cylindrical portion 17c that is one size larger is formed integrally with the end of the cylindrical portion 17a in a coaxial state via an annular step surface 17b. A head fixing nut 19 is coaxially attached to the outer periphery of the cylindrical portion 17b in a rotatable state.

The head fixing nut 19 protrudes inward from a cylindrical portion 19a, a female screw portion 19b formed on a circular inner peripheral surface portion of the cylindrical portion 19a on the head mounting side, and an inner peripheral surface portion on the opposite side of the cylindrical portion 19a. And an annular flange 19c. The annular flange 19c is inserted into an annular groove 17d formed on the outer peripheral surface of the cylindrical portion 17c of the hosel portion 17 so as to be rotatable around its central axis.

Note that a decorative truncated cone-shaped cap 20 made of a synthetic resin material is connected and fixed coaxially with an adhesive or the like to the end of the cylindrical portion 19a opposite to the head mounting side. The cap 20 covers and conceals the head fixing nut 19 and the hosel portion 17.

Next, on the side of the golf club head 13, a cylindrical portion 13 b having a shaft insertion hole 18 having a circular cross section with a certain depth into which the hosel portion 17 can be inserted is formed. An elastic disk 21 having a certain thickness is attached to the bottom surface 18a of the shaft insertion hole 18. A male screw portion 13c is formed on the outer peripheral surface portion of the tip portion of the cylindrical portion 13b. The male screw portion 13 c can be screwed into the female screw portion 19 b of the head fixing nut 19.

Next, the auxiliary shaft 16 is a shaft having a circular cross section, and has an outer diameter dimension that can be inserted into the hollow portion 15a of the main shaft 15. One end of the auxiliary shaft 16 is a large-diameter head 16a, and the head 16a has a size that can be inserted into the shaft insertion hole 18. Here, the depth dimension of the shaft insertion hole 18 is the total dimension of the length of the cylindrical portion 17a for insertion of the hosel portion 17, the thickness of the head portion 16a of the auxiliary shaft 16, and the thickness of the elastic disc 21. Is set to a shorter length.

In the golf club 11 having this configuration, the auxiliary shaft 16 is inserted into the shaft insertion hole 18 of the golf club head 13. Next, the hosel portion 17 of the main shaft 15 is inserted into the shaft insertion hole 18 of the golf club head 13 while the auxiliary shaft 16 is inserted into the hollow portion 15 a of the main shaft 15. Then, the head fixing nut 19 attached to the hosel portion 17 is turned to fasten and fix the main shaft 15 to the golf club head 13.

As a result, as shown in FIG. 3B, the annular step surface of the hosel portion 17 is in contact with the tip surface of the cylindrical portion on the golf club head 13 side. In this state, the head 16a of the auxiliary shaft 16 is sandwiched between the front end surface of the hosel portion 17 and the bottom surface of the shaft insertion hole 18 via an elastic disk, and the elastic disk is compressed by a predetermined amount. . Therefore, the golf club head 13 and the golf club shaft 2 are connected and fixed without backlash. Further, in this state, the auxiliary shaft 16 is in close contact with the inner peripheral surface of the main shaft 15, and a state in which the

shafts

15 and 16 are mechanically engaged is formed.

FIG. 4 is an explanatory diagram showing the shapes of the main shaft 15 and the auxiliary shaft 16. In this example, as shown in FIGS. 4A and 4B, the hollow portion 15a portion of the main shaft 15 into which the auxiliary shaft 16 is inserted has the same inner diameter in the axial direction. The auxiliary shaft 16 also has the same outer diameter in the axial direction at the portion inserted into the hollow portion 15a of the main shaft 15. The auxiliary shaft 16 includes a shaft body portion 16A and a coating layer 16B having a constant thickness formed on the surface thereof. The coating layer 16 </ b> B is formed on a portion of the surface of the auxiliary shaft 16 that comes into contact with another member. In the illustrated example, the shaft main body portion 16A is formed so as to cover the front surface portion except the outer peripheral surface 16b and the back surface 16c of the head portion 16a.

One or both of the coating layer 16B and the inner peripheral surface portion of the main shaft 15 with which the coating layer 16B abuts can be formed from a carbon fiber-containing material, such as a carbon fiber reinforced plastic. In this case, it is desirable to increase the carbon fiber content and reduce the frictional resistance between them. For example, when a prepreg material is used, it is desirable to use a carbon fiber content of 67% by weight or more. In addition, it is desirable to use a higher elastic material as the contained carbon fiber material because the frictional resistance of the contact portion can be lowered. For example, it is desirable to have an elastic modulus of about 24 t (24 tf / mm ² ) or more.

Further, it is desirable that the coating layer 16B is formed of a material having a surface hardness lower than that of the main shaft 15. Thereby, backlash between the auxiliary shaft 16 and the main shaft 15 can be prevented. For example, it is desirable to form the coating layer 16B from a material having a surface hardness of R120 or less in terms of Rockwell hardness.

Furthermore, when the shaft main body portion 16A of the auxiliary shaft 16 is made of carbon fiber reinforced plastic, the coating layer 16B can also provide an advantage that cracking and tearing, which are weak points of the carbon fiber reinforced plastic material, can be prevented.

4C and 4D are explanatory views showing another example of the auxiliary shaft 16. The auxiliary shaft 26 shown in these drawings is formed with a coating layer 26B having a constant thickness extending linearly in the axial direction at intervals of 90 degrees in the circumferential direction on the outer peripheral surface of the shaft body 26A. Only the coating layer 26 </ b> B of the auxiliary shaft 26 is in contact with the inner peripheral surface 15 b of the main shaft 15. Therefore, wear of the auxiliary shaft 26 and the main shaft 15 can be prevented, and backlash between them can also be prevented.

4E and 4F are explanatory views showing still another example of the auxiliary shaft 16. In the auxiliary shaft 36 shown in these drawings, a coating layer 36B is formed in an annular shape on the outer peripheral surface of the shaft main body 36A at regular intervals along the axial direction. Even in this case, only the coating layer 36 </ b> B of the auxiliary shaft 36 is in contact with the inner peripheral surface 15 b of the main shaft 15. Therefore, wear of the auxiliary shaft 36 and the main shaft 15 can be prevented, and backlash between them can also be prevented.

In addition, the auxiliary shaft comprised from the shaft main body and the coating layer can also be applied to the auxiliary shaft 6 of the golf club 1 of the first embodiment shown in FIGS.

(Other embodiments)
In the first and second embodiments, the auxiliary shaft having a constant outer diameter is inserted into the hollow portion having a constant inner diameter of the main shaft. Instead of this, it is possible to adopt the shape shown in FIG.

As shown in FIG. 5 (a), the portion of the main shaft 45 where the auxiliary shaft 46 is inserted is formed into a cylindrical shape whose outer diameter gradually increases toward the grip side, so that the inner diameter remains the same. can do. On the contrary, as shown in FIG. 5B, the thickness of the auxiliary shaft 56 inserted into the hollow portion 55a of the main shaft 55 having the same diameter from the front end side (head side) of the golf club shaft is rearward. A cross-sectional shape that gradually decreases toward the end side (grip side) can also be used. Furthermore, as shown in FIG. 5C, the auxiliary shaft 66 has a cross-sectional shape in which a large diameter portion and a small diameter portion are alternately formed, and is arranged on the inner peripheral surface of the main shaft 65 at regular intervals along the axial direction. You may make it contact | abut.

Next, in each of the above embodiments, the auxiliary shaft is inserted into the hollow portion from the opening on the front end side of the main shaft. Conversely, the auxiliary shaft may be inserted through an opening formed at the rear end of the main shaft on the grip side. In this case, a cap capable of closing the insertion opening at the rear end of the main shaft may be attached to the end of the auxiliary shaft. For example, the hollow portion on the main shaft side has a shape in which the inner diameter gradually decreases from the rear end toward the front end. A columnar or cylindrical auxiliary shaft having an outer diameter gradually decreasing toward the tip can be inserted here.

Experimental example

The present inventors conducted various experiments in order to verify the effect of the auxiliary shaft. An experimental example of the golf club shaft according to the first embodiment conducted by the present inventors will be described below.

(Experimental result)
In this experiment, the auxiliary shaft 6 having different characteristics was attached to the main shaft 5 and the bending rigidity (tip bending rigidity) of the tip portion of the golf club shaft 2 was measured. In this experiment, two types of the auxiliary shaft 6 were used: a high-rigidity shaft using high-elasticity carbon and a low-rigidity shaft having lower rigidity. Further, the insertion length into the main shaft 5 was changed by 50 mm from 235 mm to 85 mm. The measurement results shown in Table 1 were obtained by this experiment.

(Table 1: Measurement values of tip bending stiffness)

(Discussion)
In a normal golf club shaft, when the hardness increases by one rank, for example, when the rank changes from rank R to rank S, the measured values (tip rigidity) shown in Table 1 decrease by about “5” to “8”. The measured value of the main shaft without the auxiliary shaft 6 was “137.4”. The measured value when a low-rigidity shaft with an insertion length of 235 mm is inserted is “132.2”. By inserting the low-rigidity shaft, the tip rigidity is almost one rank compared to the case without an auxiliary shaft. It was confirmed to go up. The measured value when using a highly rigid shaft with the same insertion length of 235 mm was “110.8”, and it was confirmed that the tip rigidity was increased by about 3 ranks compared to the case without the auxiliary shaft.

Next, the measurement value when using a high-rigidity shaft with an insertion length of 85 mm is “132.9”, and the measurement value when using a low-rigidity shaft with an insertion length of 235 mm is “132.2”. It was confirmed that the tip rigidity was almost the same. In this case, in this experiment, it is evaluated that the tip rigidity is the same.

However, in practice, when the adjustment mode of the bending rigidity is different, for example, when the rigidity is greatly changed for a short range in the golf club shaft and when the rigidity is changed moderately for a long range in the golf club shaft, There are significant differences in trajectory, flight distance, and feeling during swing. This indicates that by inserting auxiliary shafts of different lengths, it is possible to adjust a wider swing characteristic than can be determined by static measurement as in this experiment.

(Measurement method, shaft used)
The measured value of the rigidity of the main shaft tip is determined by freezing the main shaft when the tip of the main shaft is clamped to support the main shaft in a cantilevered state and the weight is lowered to the free end of the main shaft. The amount of bending from the no-load state at the end side position is shown. The distance from the clamp position on the main shaft to the position where the weight is applied is 24.0 inches (609.6 mm), the weight 102 is 2.7 kg, and the measurement position of the deflection amount is 27.56 inches (700.01 mm) from the clamp position. ) Distance point.

In the experiment, the tip stiffness was measured with only the main shaft. The auxiliary shaft was inserted, the insertion length was changed by 50 mm, and the tip rigidity was measured without changing other conditions.

The specifications of the main shaft used in the experiment are shown below.
Shaft natural frequency: 268 (times / min)
Mass: 65g
Tip outer diameter: 8.5 mm
Tip internal shape: Parallel cylinder shape with inner diameter of 5.45 mm and length of 235 mm Hand outer diameter: 15.4 mm
Total length: 1168mm

The specifications of the auxiliary shaft used are shown below.
High rigidity shaft Mass per unit length: 0.208 g / cm
Shape: Parallel cylindrical shape with outer diameter of 5.45 mm Bending rigidity: 0.384 inch (9.76 mm)
Low rigidity shaft Mass per unit length: 0.188 g / cm
Shape: Parallel cylindrical shape with outer diameter of 5.45 mm Bending rigidity: 0.045 inch (1.14 mm)

The measured value of the bending stiffness of the auxiliary shaft is expressed as the amount of deflection from the unloaded state by supporting the auxiliary shaft in a horizontal state with a span of 15.0 inches (381 mm) and suspending a weight of 880 g at the center. Yes.

DESCRIPTION OF SYMBOLS 1 Golf club 2 Golf club shaft 3 Golf club head 3a Sole surface 4 Grip 5 Main shaft 5a Hollow part 5c Insertion opening part 6 Auxiliary shaft 6a End part 6b Bolt head part 6c Male thread part 7 Hosel part 8 Shaft insertion hole 8a Tip opening 8b Rear end opening 8c Circular hole portion 8d Large diameter hole portion 8e Annular step surface 9 Head fixing screw

9a Head portion

9b Leg portion 9c Male screw portion 11 Golf club 12 Golf club shaft 13 Golf club head 13a Sole surfaces 15, 45, 55 65 Main shaft

15a Hollow portion

16, 26, 36, 46, 56, 66 Auxiliary shaft

16a Head portion

16A, 26A, 36A

Shaft body portion

16B, 26B, 36B Cover layer 17 Hosel portion 17a Cylindrical portion 17b Annular step surface 17c Cylindrical portion 17d Groove 18 Shaft insertion 18a hole bottom 19 head fixing nut 19a cylindrical portion 19b internally threaded portion 19c annular flange 20 cap 21 elastic disc

Claims

A main shaft,
An auxiliary shaft used to adjust the bending rigidity of the main shaft;
A hollow portion for inserting an auxiliary shaft formed coaxially with the main shaft inside the main shaft;
In order to insert the auxiliary shaft into the hollow portion, it has an insertion opening formed on the front end surface of the golf club head side of the main shaft or the rear end surface of the grip side,
The auxiliary shaft inserted into the hollow portion is detachably connected and fixed to the main shaft,
A golf club shaft, wherein at least a part of an outer peripheral surface of the auxiliary shaft inserted into the hollow portion is mechanically engaged with an inner peripheral surface of the hollow portion.
In claim 1,
The auxiliary shaft includes a shaft main body portion and a coating layer formed to cover at least a part of a surface portion of the shaft main body portion facing the inner peripheral surface of the hollow portion of the main shaft. ,
The golf club shaft, wherein the coating layer is formed of a material having a lower surface hardness than the shaft main body portion.
A golf club shaft according to claim 1;
A golf club head fixed to the tip of the golf club shaft,
The insertion opening is formed in the tip surface of the main shaft;
The golf club head has an insertion hole for inserting an auxiliary shaft extending coaxially with the main shaft,
One end of the insertion hole opens in the sole surface of the club head, and the other end communicates with the insertion opening of the main shaft,
The golf club according to claim 1, wherein the auxiliary shaft is inserted into the hollow portion from the sole surface side of the club head.
In claim 3,
2. The golf club according to claim 1, wherein the auxiliary shaft includes a weight portion for adjusting a head weight positioned in the insertion hole of the golf club head in a state where the auxiliary shaft is inserted into the hollow portion of the golf club shaft.
A golf club shaft according to claim 1;
A golf club head fixed detachably to the tip of the main shaft of the golf club shaft;
The golf club according to claim 1, wherein the insertion opening is formed on the tip surface of the main shaft.
In claim 5,
A head fixing bracket for connecting and fixing the golf club head in a detachable state to the tip of the main shaft;
The golf club head has an insertion hole for inserting a head fixing bracket extending coaxially with the main shaft,
One end of the insertion hole opens in the sole surface of the club head, and the other end communicates with the insertion opening of the main shaft,
The auxiliary shaft is inserted into the hollow portion from the sole surface side of the club head together with the head fixing bracket while being connected and fixed to the head fixing bracket.
In claim 6,
2. The golf club according to claim 1, wherein the auxiliary shaft includes a weight portion for adjusting a head weight located in the insertion hole of the golf club head in a state where the auxiliary shaft is inserted into the hollow portion of the main shaft.
In claim 5,
A head fixing bracket for connecting and fixing the golf club head in a detachable state to the tip of the main shaft;
A part of the auxiliary shaft is clamped between the main shaft and the golf club head, which are connected and fixed by the head fixing bracket.
In claim 8,
The golf club according to claim 1, wherein the part of the auxiliary shaft is sandwiched between the main shaft and the golf club head via an elastic member.