Patent Application
20230001275
The present disclosure relates to a golf club and a weight member therefor.
The club balance of a golf club affects the golfer's swing, and depending on the abilities of golfers, the club balance suitable for each golfer differs.
The following Patent Document 1 discloses a golf club in which a weight member for adjusting the club balance is attached to an end of the club shaft. The club balance suitable for a golfer differs depending on the ability of the golfer.
When a golf club as described above is industrially manufactured, in order to mount the weight member in the hollow of the shaft, the outer diameter of the weight member needs to be formed with high accuracy so as to match the inner diameter of the hollow of the shaft.
On the other hand, such weight member makes it difficult to insert the weight member into the hollow of the shaft, which deteriorates the productivity. Further, the weight member needs to be stably held in the hollow of the shaft even when it receives an impact force at the time of hitting a ball.
The present disclosure is therefore, made in view of the above circumstances, and a primary objective of the present disclosure is to provide a golf club in which a weight member is stably held in a club shaft without deteriorating the productivity.
According to the present disclosure, a golf club comprises a tubular shaft and a weight member, wherein
the shaft is provided with a hollow therein and has a first end having a first inner diameter D1 and a second end on the opposite side of the first end, and
the weight member is attached to the first end, and comprises an insertion portion disposed in the hollow,
an engaging portion which is, on the outside of the shaft, engaged with the first end,
a plurality of protrusions protruding radially of the shaft from the insertion portion,
each of the protrusions is made of an elastically deformable material,
the outer diameter D2 of the insertion portion is smaller than the first inner diameter D1 of the shaft,
the maximum outer diameter D3 of the insertion portion including the protrusions is larger than the first inner diameter D1,
each of the protrusions has a tapered portion in which the radially outwardly protruding height of the protrusion from the insertion portion is decreased toward the second end,
the length Lt of each tapered portion measured along the axial direction of the shaft is more than 50% of the maximum length L of the protrusion measured along the axial direction of the shaft, and
in a state of the weight member which is attached to the shaft by inserting the insertion portion in the hollow, each of the protrusions at least partially contacts the inner surface of the shaft in a state of being compressively elastically deformed.
Therefore, according to the present disclosure, the weight member can be stably held in the shaft without deteriorating the productivity of the golf club.
Embodiments of the present disclosure will now be described in detail in conjunction with accompanying drawings.
Throughout the description, the same or common elements of the embodiments are designated by the same reference numeral, and redundant explanations are omitted.
As shown in
In the cross sections of the shaft 2 which are orthogonal to the shaft axial direction, the outer peripheral surface 2o and inner surface 2i of the shaft 2 are circular, therefore, the shaft 2 is formed in the form of a hollow circular cylinder. The shaft 2 in this example is made of a fiber reinforced resin. However, as another example, the shaft 2 may be made of a metallic material.
The shaft 2 has a first end 2a and a second end 2b on the opposite side thereto in the axial direction of the shaft.
The first end 2a of the shaft 2 has a first inner diameter D 1. For example, the first inner diameter D 1 is about 12 to 16 mm.
In this embodiment, the first end 2a of the shaft 2 has an outer diameter and an inner diameter larger than those of the second end 2b. However, the shaft 2 may be configured with a constant outer diameter and inner diameter over the entire length.
As shown in
As shown in
a grip portion 4a to be gripped by a golfer, and
a rear/butt end portion 4b provided on one end side of the grip portion 4a.
The grip portion 4a is tapered toward the other end of the grip portion 4a on the opposite side to the rear/butt end portion 4b and has a substantially circular cylindrical outer shape. The other end is provided with an opening into which the shaft 2 can be inserted.
The rear/butt end portion 4b covers the first end 2a of the shaft 2. The rear/butt end portion 4b is provided with a through hole 4c communicating with the inside of the grip 4 for exhausting air when the shaft 2 is inserted in the grip 4.
In the present embodiment, as shown in
Hereinafter, regarding the weight member 5, one of two sides in the shaft axial direction on the first end 2a side may be referred to as the “posterior end side”, and the other of the two sides on the second end 2b side may be referred to as the “anterior end side”.
Incidentally, the weight member has a center line which coincides with the shaft center line when attached to the shaft, therefore, when the weight member alone is described, the shaft center line can be read as the center line of the weight member. Further, the axial direction of the shaft and the circumferential direction of the shaft can be read as the axial direction of the weight member and the circumferential direction of the weight member, respectively.
The weight member 5 in the present embodiment comprises an insertion portion 51 disposed in the hollow (i) of the shaft 2, an engagement portion 52 which is, on the outside of the shaft 2, engaged with the first end 2a, and
a plurality of protrusions 53 which protrude from the insertion portion 51 radially of the shaft center line.
As shown in
The insertion portion 51 in the present embodiment is formed in the form of a hollow circular cylinder. But, the insertion portion 51 may be formed in the form of a solid circular column or a solid polygonal column.
Although not particularly limited, preferably, the mass of the weight member 5 is about 1 to 100 g, for example.
In the state of the insertion portion 51 not yet inserted in the shaft 2, the outer diameter D2 (
The outer diameter D2 of the insertion portion 51 may be constant or may vary in the shaft axial direction. When the outer diameter of the insertion portion 51 varies, the outer diameter D2 means the maximum outer diameter.
The engaging portion 52 is formed so as to project radially outwardly at the end on the posterior end side, of the insertion portion 51, for example. As shown in
Therefore, as shown in
Preferably, the engaging portion 52 is sandwiched and held between
the end surface of the first end 2a of the shaft 2 and
the inner surface of the rear/butt end portion 4b of the grip 4.
As another example of the engaging portion 52, the engaging portion 52 may be made up of a plurality of portions projecting radially outward of the inserting portion 51.
In the present embodiment, the protrusions 53 are arranged around the insertion portion 51 at positions on the engaging portion 52 side of the tip of the inserting portion 51 in the shaft axial direction.
The protrusions 53 are spaced apart from the engaging portion 52 by a distance Y in the shaft axial direction.
The protrusions 53 are preferably arranged at equal intervals in the circumferential direction of the shaft as shown in
Each of the protrusions 53 is made of an elastically deformable material, preferably a rubber-like elastic material.
The rubber-like elastic material has rubber elasticity, and includes vulcanized rubber and resin-based elastomers.
In the present embodiment, the protrusions 53 are made of vulcanized rubber. In the present embodiment, the protrusions 53 as well as the insertion portion 51 and the engagement portion 52 are made of a rubber-like elastic material.
In order to provide a larger weight, a metal material or the like may be embedded in the insertion portion 51 although such example is not shown.
As shown in
Here, the “maximum outer diameter D3 of the insertion portion 51 including the protrusions 53” is equal to twice the distance in the radial direction of the shaft from the central axis line of the insertion portion 51 to the radially outermost position of each protrusion 53.
As shown in
In the tapered portion 6, its protruding height (t) measured in the radial direction of the shaft from the insertion portion 51 is decreased toward the second end 2b side of the shaft 2.
In the weight member 5 in the present embodiment, the length Lt of the tapered portion 6 measured in the shaft axial direction is set to be larger than 50%, preferably not less than 95%, more preferably substantially 100% of the maximum length L of the protrusion 53 measured in the shaft axial direction.
In the weight member 5 configured as described above, since the outer diameter D2 of the insertion portion 51 is smaller than the first inner diameter D1 of the shaft, the insertion portion 51 can be easily inserted into the hollow (i) of the shaft 2 from the first end 2a side of the shaft 2. This facilitates the work process of inserting the weight member 5 into the hollow (i) of the shaft 2, and helps to improve the productivity of the golf club 1.
In order to enhance such function, it is preferred that the difference between the outer diameter D2 and the first inner diameter D1 is set to be about 0.10 to 0.15 mm although the difference is not particularly limited.
When the insertion portion 51 of the weight member 5 is further inserted into the hollow (i) of the shaft 2, the engaging portion 52 butts with the first end 2a on the outside of the shaft 2, and the insertion portion is positioned at its place.
Thus, this makes it always possible to mount the weight member 5 at the fixed correct position with respect to the shaft 2, and helps to keep the balance of the golf club 1 constant.
Further, the weight member 5 is formed so that the maximum outer diameter D3 of the insertion portion 51 including the protrusions 53 is larger than the first inner diameter D1 of the shaft 2. Therefore, as shown in
Therefore, due to the frictional force and normal force between the protrusions 53 and the inner surface 2i of the shaft 2, the weight member 5 is stably held in the circumferential direction, axial direction and radial direction of the shaft.
Further, in the protrusions 53 of the present embodiment, since the length Lt of the tapered portion 6 is larger than 50% of the maximum length L of the protrusion 53, each protrusion 53 can contact the inner surface 2i of the shaft 2 in a wider range to generate great holding power, without deteriorating the insertion workability into the shaft 2.
Further, in the protrusions 53 in the present embodiment, due to the shape of each protrusions 53, the center of gravity of each protrusion 53 is relatively sifted to the first end 2a side of the weight member 5.
This makes it possible to shift the position of the center of gravity of the weight member 5 toward the first end 2a of the shaft 2, and thus enhance the counterbalance effect on the golf club 1.
The distance Y (
The space between the protrusions 53 and the engaging portion 52 can be utilized for the protrusions 53 to make the elastic deformation. As a result, the weight member 5 can be surely stably inserted into the shaft 2 up to a position where the engaging portion 52 comes into contact with the end surface of the first end 2a of the shaft 2.
As shown in
In the present embodiment, the entire first surface 5a is inclined with respect to the shaft axial direction and forms the tapered portion 6 tapered toward the second end 2b side of the shaft 2.
In the present embodiment, the protrusion 53 has a second surface 5b and a third surface 5c on both sides in the shaft axial direction, of the first surface 5a.
The second surface 5b defines the end of the protrusion 53 on the taper tip end side.
In the present embodiment, the second surface 5b is substantially parallel to a radial direction determined at the circumferential position of the protrusion 53 concerned. Here, the expression “substantially parallel” means that an inclination of up to 5 degrees is allowed.
In the present embodiment, at the position in the shaft axial direction, of the second surface 5b, the protruding height (t) of the protrusion 53 is the minimum. Although not particularly limited, it may be possible to set the outer diameter D4 of the insertion portion 51 including the protrusions 53, at the position in the shaft axial direction, of the second surface 5b, to be smaller than the first inner diameter D1 of the shaft 2. In this case, when the weight member 5 is inserted into the hollow (i) of the shaft 2, the insertion can be prevented from being hindered by the contact between the second surface 5b and the end surface of the first end 2a of the shaft 2, and the even smoother insertion work is possible.
The third surface 5c defines the end of the protrusion 53 on the taper butt end side.
In the present embodiment, the third surface 5c is substantially parallel to a radial direction determined at the circumferential position of the protrusion 53 concerned. Here, again the expression “substantially parallel” means that an inclination of up to 5 degrees is allowed.
In the present embodiment, at the position in the shaft axial direction, of the third surface 5c, the protruding height (t) of the protrusion 53 is the maximum.
The outer diameter of the insertion portion 51 including the protrusions 53 at the position in the shaft axial direction, of the third surface 5c defines the above-mentioned maximum outer diameter D3. In this case, when the weight member 5 is inserted into the hollow (i) of the shaft 2, at least a part of the protrusion 53 in the vicinity of the third surface 5c can be elastically compressed and deformed.
However, it is preferable that, in the state of the weight member 5 mounted in the shaft 2, the entire first surfaces 5a of the protrusions 53 come into contact with the inner surface 2i of the shaft 2 as shown in
Such configuration or design can be easily realized by adjusting the maximum outer diameter D3 of the weight member 5 in relation to the first inner diameter D1 of the shaft 2, and the taper angle of the tapered portion 6.
In the golf club 1 in the present embodiment, it is preferable that the compression deformation rate of the protrusion 53 is set in a range from 1% to 25 %.
The compression deformation rate is given by the following expression (1):
(D3−D1)/D3×100
wherein
D1 is the above-mentioned first inner diameter of the shaft 2, and
D3 is the above-mentioned maximum outer diameter of the insertion portion 51 including the protrusion 53.
By setting the compression deformation rate within the above-mentioned range, it is possible to optimize the work of inserting the weight member 5 into the shaft 2 and the holding force of the weight member 5 at the same time.
When the compression deformation rate is less than 1%, the holding force of the weight member 5 with respect to the shaft 2 tends to become small, therefore, as the golf curb is used, the weight member 5 may fall off or make an abnormal noise during swinging.
From this point of view, the compression deformation rate is more preferably not less than 5%, still more preferably not less than 10%.
On the contrary, if the compression deformation rate exceeds 25%, the work of inserting the weight member 5 into the shaft 2 may become significantly difficult. From this point of view, the compression deformation rate is more preferably not more than 20%, still more preferably not more than 15%.
Further, it is preferable that the golf club 1 of the present embodiment satisfies the following conditional expression (2): 2.0≤W/S≤25.0
wherein
W is the mass in grams of the weight member 5, and
S is the total contact area in sq.cm between the plurality of protrusions 53 and the inner surface 2i of the shaft 2.
The conditional expression (2) specifically limits the mass W of the weight member 5 shared by the unit contact area of the protrusions 53.
By specifying the ratio W/S in this way, even when the weight member 5 has a large mass, a large force for holding the weight member 5 can be secured to prevent it from falling off, while maintaining the smooth insertion work of the weight member 5 into the hollow (i) of the shaft 2.
If the ratio W/S is small, there is no particular problem in the stability of the weight member 5 after mounted.
The ratio W/S is set to be not less than 2.0 (g/sq.cm) for a practical reason, preferably set to be not less than 5 (g/sq.cm), more preferably not less than 10 (g/sq.cm).
If the ratio W/S exceeds 25.0 (g/sq.cm), the contact area of the protrusion 53 becomes too small for the mass of the weight member 5, and as a result, there is a possibility that the weight member 5 falls off as the golf club is used, or an abnormal noise is generated during swinging. Further, the stability of the weight member 5 after mounted may be deteriorated.
From this point of view, the ratio W/S is more preferably not more than 20 (g/sq.cm), still more preferably not more than 15 (g/sq.cm).
In order that the weight member 5 satisfies the conditional expression (2), it is possible to adjust the total area of the first surfaces 5a of the protrusions 53 and/or the number of the protrusions 53, taking the mass of the weight member 5 into consideration.
For example, when the total area of the first surfaces 5a is large, the number of protrusions 53 can be decreased as shown in
In order to obtain a sufficient contact area with the shaft 2, the above-mentioned maximum length L of each protrusion 53 is set to be not less than 2 mm, preferably not less than 5 mm, more preferably not less than 10 mm. Further, in order to give appropriate rigidity resisting compression to the protrusions 53, the width of each protrusion 53 is set to be not less than 2 mm, preferably not less than 4 mm, more preferably not less than 6 mm.
Here, the width is measured in the direction of the tangent line to the protrusion extending in the shaft circumferential direction.
Each of
In the example shown in
In this example, the above-mentioned second surface 5b on the taper tip end side is not provided in substance. Therefore, in this example, the taper tip end of the protrusion 53 is merged into the insertion portion 51 without forming a step. As a result, the durability of the protrusion 53 may be improved.
In this example, the triangular shape of the side surface is continued to the side surface on the opposite side as the cross-sectional shape of the protrusion 53. But, the cross-sectional shape may be varied between the two side surfaces, or the shape of the side surface may be different from that on the opposite side.
The example shown in
In this example, the first surface 5a is made up of the above-mentioned tapered portion 6 and a non-tapered portion 7.
In the non-tapered portion 7, the protruding height (t) is constant along the shaft axial direction.
In the tapered portion 6, the protruding height (t) is decreased toward the second end 2b side of the shaft 2 as explained above.
In this example, the above-mentioned second surface 5b on the taper tip end side is not provided in substance. Therefore, in this example, the taper tip end of the protrusion 53 is merged into the insertion portion 51 without forming a step. Further, in this example, the trapezoidal shape of the side surface is continued to the side surface on the opposite side as the cross-sectional shape of the protrusion 53. But, the cross-sectional shape may be varied between the two side surfaces, or the shape of the side surface may be different from that on the opposite side.
The examples shown in
In each example, the protrusion 53 is provided in the first surface 5a, with a groove 9 extending in the circumferential direction of the shaft.
In the example shown in
In the example shown in
Such grooves 9 promote deformation of the protrusion 53 and helps to provide a smoother insertion operation.
The groove 9 continually extends from one of the side surfaces to the other. In these example, the shape of one of the side surfaces is continued to the side surface on the other side as the cross-sectional shape of the protrusion 53.
While detailed description has been made of preferable embodiments of the present disclosure, the present disclosure can be embodied in various forms without being limited to the illustrated embodiments.
In order to confirm the effects of the present disclosure, different kinds of weight members having specifications listed in Table 1 were experimentally manufactured, and the following tests were conducted thereon.
For each kind of the weight member, each of five workers inserted thirty weight members into respective shafts, and then attached identical thirty grips thereto respectively, and the total working time of each worker was obtained. Then, for each kind of the weight member, the average of the total working time of the five workers was obtained.
The results are indicated in Table 1 by an index based on Example 3 being 100, wherein the smaller value is better.
Golf clubs to which the different kinds of the weight members were respectively attached were prepared, and hit golf balls 3000 times per golf club. Then, in order to check the condition of the weight member, the grip was removed, and displacements in the shaft axial direction and shaft radial direction from the initial mounting position were measured.
The results are indicated in Table 1 by an index based on Example 3 being 100, wherein the smaller value is better.
From the test results, it was confirmed that the weight members according to the present disclosure were stably held inside the shaft without deteriorating the productivity.
The present disclosure is as follows:
Disclosure 1: A golf club comprising a tubular shaft and a weight member, wherein
Disclosure 2: The golf club according to Disclosure 1, wherein in each of the protrusions, the length Lt of the tapered portion is not less than 95% of the maximum length L of the protrusion.
Disclosure 3: The golf club according to Disclosure 1 or 2, wherein each of the protrusions has a first surface facing the inner surface of the shaft, and the entire first surface is in contact with the inner surface of the shaft.
Disclosure 4: The golf club according to Disclosure 1, 2 or 3, wherein a compression deformation rate of the protrusion given by (D3-D1)/D3×100 is in a range from 1% to 25%, wherein D1 is said first inner diameter of the shaft, and D3 is said maximum outer diameter of the insertion portion including the protrusions.
Disclosure 5: The golf club according to Disclosure 1, 2, 3 or 4, wherein a ratio W/S of the mass W in grams of the weight member and the total contact area S in sq.cm between the plurality of protrusions and the inner surface of the shaft is not less than 2.0 but not more than 25.0.
Disclosure 6: The golf club according to any one of Disclosures 1 to 5, wherein, in a state of the weight member not mounted on the shaft, the centroid of each protrusion is positioned on the first end side of the middle position of the maximum length of the protrusion measured in the shaft axial direction.
Disclosure 7: The golf club according to any one of Disclosures 1 to 6, wherein the protrusions are arranged at equal intervals in the circumferential direction of the shaft.
Disclosure 8: The golf club according to any one of Disclosures 1 to 7, wherein each of the protrusions is spaced apart from the engaging portion by a distance Y in the shaft axial direction, and the distance Y is not less than 1 mm.
Disclosure 9: The golf club according to any one of Disclosures 1 to 8, wherein each of the protrusions has a side surface having a triangular shape.
Disclosure 10: The golf club according to Disclosure 9, wherein each of the protrusions has a side surface on the opposite side to said side surface, and the triangular shape of said side surface is continued to the side surface on the other side as the cross-sectional shape of the protrusion, whereby on the side of the tip end of the tapered portion, the protrusion is merged into the insertion portion without forming a step.
Disclosure 11: The golf club according to any one of Disclosures 1 to 10, wherein each of the protrusions has a side surface having a trapezoidal shape.
Disclosure 12: The golf club according to Disclosure 11, wherein each of the protrusions has a side surface on the opposite side to said side surface, and the trapezoidal shape of said side surface is continued to the side surface on the other side as the cross-sectional shape of the protrusion, so that a non-tapered portion in which the protruding height is constant in the shaft axial direction is formed on the engaging portion side of the tapered portion.
Disclosure 13: A weight member for a golf club,
Disclosure 14: The weight member according to Disclosure 13, wherein in each of the protrusions, the length Lt of the tapered portion is not less than 95% of the maximum length L of the protrusion.
Disclosure 15: The weight member according to Disclosure 13 or 14, wherein the centroid of each protrusion is positioned on the first end side of the middle position of the maximum length of the protrusion measured in the shaft axial direction.
Disclosure 16: The weight member according to Disclosure 13, 14 or 15, wherein each of the protrusions is spaced apart from the engaging portion by a distance Y in the shaft axial direction, and the distance Y is not less than 1 mm.
Disclosure 17: The weight member according to any one of Disclosures 13 to 16, wherein each of the protrusions has a side surface having a triangular shape.
Disclosure 18: The weight member according to Disclosure 17, wherein each of the protrusions has a side surface on the opposite side to said side surface, and the triangular shape of said side surface is continued to the side surface on the other side as the cross-sectional shape of the protrusion, whereby on the side of the tip end of the tapered portion, the protrusion is merged into the insertion portion without forming a step.
Disclosure 19: The weight member according to any one of Disclosures 13 to 16, wherein each of the protrusions has a side surface having a trapezoidal shape.
Disclosure 20: The weight member according to Disclosure 19, wherein each of the protrusions has a side surface on the opposite side to said side surface, and the trapezoidal shape of said side surface is continued to the side surface on the other side as the cross-sectional shape of the protrusion, so that a non-tapered portion in which the protruding height is constant in the shaft axial direction is formed on the engaging portion side of the tapered portion.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-109149 | Jun 2021 | JP | national |
