GOLF CLUB SET
A golf club set having a stable swing feel for the player is obtained regardless of the club number. Moments of inertia of the grips of respective the golf clubs are substantially uniform regardless of the respective golf club numbers. Moments of inertia of the heads of respective the golf clubs decrease as the respective golf club numbers increase. Moments of inertia of the shafts of respective golf clubs increase as the numbers of respective golf clubs increase. Moments of inertia of the golf clubs are made substantially the same by cancelling out the decrease in moments of inertia of the heads and the increase in moments of inertia of the shafts. The shafts of the golf clubs increase in weight, and respective gravity center locations of the shafts are located closer to the tip ends of the shafts, as the numbers of the golf clubs increase.
This application is entitled to the benefit of and incorporates by reference subject matter disclosed in the International Patent Application No. PCT/JP2016/056963 filed on Mar. 7, 2016 and Japanese Patent Application No. 2015-045511 filed on Mar. 9, 2015.
TECHNICAL FIELDThe present invention relates to a golf club set.
BACKGROUND ARTGolf club sets (e.g., iron sets) include a plurality of golf clubs labeled with different numbers (e.g., from a 5-iron to a 10-iron). Golf clubs with different numbers are usually different in length and gross weight (shaft length and head weight).
Conventional golf club sets are usually assembled so that all the numbered golf clubs, which are different in length and gross weight, become mutually substantially identical in swingweight (swing balance) by appropriately selecting shafts and heads. Swingweight is a numerical value (measurement value) that indicates how effective the head of a golf club works (how heavy the head of a golf club feels when one swings or waggles that club); the heavier the swing balance of a golf club, the heavier the club head feels, and the lighter the swing balance of a golf club, the less heavy the club head feels.
Club moment of inertia (MOI[kg/cm2]) is known as a different index from swingweight. Club moment of inertia is defined as the sum of the moments of inertia of the head, shaft and grip of the golf club from the grip end and is used as an index to describe the feeling of swinging a golf club. It is said, as a general tendency, that a golf club becomes more difficult to swing as the club moment of inertia increases, and that a golf club becomes easier to swing as the club moment of inertia decreases.
SUMMARYThe inventors of the present invention have completed the present invention based on the findings that all the golf clubs of an entire golf club set can be made uniform in swinging ease if the club moment of inertia (MOI[kg/cm2]) is used as a new common index for golf club sets, rather than for each individual golf club. Specifically, the inventors of the present invention have found that players tend to evaluate a golf club set as an easy-to-swing golf club set if all the golf clubs thereof have a matching club moment of inertia rather than the size of each individual golf club (though the size of each individual golf club cannot be ignored).
In conventional golf club sets made while focusing simply on providing matching swingweights for the clubs, it is difficult to provide matching clubs by moment of inertia. In a conventional swingweight-matched set of golf clubs, the club moment of inertia (MOI[kg/cm2]) decreases (increases) as the club number increases (decreases). Accordingly, in conventional golf club sets, the reality is that the club moment of inertia (i.e., the feeling of swinging a golf club) varies depending on the club number. This is assumed to be a cause of creating discrepancies in performance depending on the club number (specifically a cause of being bad at using a club with a low number).
The present invention has been devised based on the awareness of the above described problems, and an object of the present invention is to achieve a golf club set with which a stable swing feel suitable for the player can be obtained regardless of the club number.
When the inventors of the present invention diverted their attention away from the general tendency that a golf club becomes more difficult (easy) to swing as the club moment of inertia increases (decreases), and directed their attention to the individual players, they found through their extensive research that in order to obtain an ideal and stable swing feel without discrepancies in performance depending on the club number, it is important for all the golf clubs of a golf club set to be mutually identical in club moment of inertia even though the golf clubs are different in club number. The present invention has been completed with the concept of matching the values of the club moments of inertia of all the golf clubs of a golf club set. As a matter of course, the values of the club moments of inertia themselves vary depending on the individual player.
A golf club set, according to the present invention, includes different numbered golf clubs, each of which is constructed by fixing a head and a grip to a tip end and a butt end of a shaft, respectively. Moments of inertia of the grips of respective the golf clubs are substantially uniform regardless of the numbers of respective the golf clubs. Moments of inertia of the heads of respective the golf clubs decrease as the numbers of respective the golf clubs increase. Moments of inertia of the shafts of respective the golf clubs increase as the numbers of respective the golf clubs increase. Moments of inertia of the golf clubs are made substantially the same by cancelling out the decrease in the moments of inertia of the heads and the increase in the moments of inertia of the shafts. The shafts of the golf clubs increase in weight, and respective gravity center locations of the shafts are located closer to the tip ends of the shafts, as the numbers of the golf clubs increase.
When one golf club is selected as a reference golf club from the golf clubs of the golf club set, it is desirable for the reference golf club and any one of remaining golf clubs of the golf club set to satisfy the following condition (1): 0.995X<Y<1.005X . . . (1), wherein X designates a club moment of inertia (MOI[kg/cm2]) of the reference golf club, and Y designates a club moment of inertia (MOI[kg/cm2]) of any one of the remaining golf clubs.
It is desirable that the golf club set according to the present invention satisfy the following condition (1′), within the range defined by the condition (1):
0.998X<Y<1.002X (1′).
At least a portion of each the golf clubs of the golf club set can include, on the tip end side of the shaft, one or both of a metal cylinder and a metal foil which increase in weight as the numbers increase.
The golf clubs of the golf club set can include at least six irons ranging from a 5-iron through to a 10-iron.
According to the present invention, a golf club set with which a stable swing feel suitable for the player is obtained regardless of the club number.
The present embodiment of the golf club set is an iron club set which includes a 5-iron 5I, a 6-iron 6I, a 7-iron 7I, an 8-iron 8I, a 9-iron 9I and a 10-iron (pitching wedge) 10I(P). Each iron club is constructed by fixing a head and a grip to the tip end and the butt end of a shaft, respectively.
The head, shaft and grip which constitute the 5-iron 5I are designated by the reference characters 5H, 5S and 5G, respectively. The shaft 5S will be hereinafter referred to as the number-5 shaft.
The head, shaft and grip which constitute the 6-iron 6I are designated by the reference characters 6H, 6S and 6G, respectively. The shaft 6S will be hereinafter referred to as the number-6 shaft.
The head, shaft and grip which constitute the 7-iron 7I are designated by the reference characters 7H, 7S and 7G, respectively. The shaft 7S will be hereinafter referred to as the number-7 shaft.
The head, shaft and grip which constitute the 8-iron 8I are designated by the reference characters 8H, 8S and 8G, respectively. The shaft 8S will be hereinafter referred to as the number-8 shaft.
The head, shaft and grip which constitute the 9-iron 9I are designated by the reference characters 9H, 9S and 9G, respectively. The shaft 9S will be hereinafter referred to as the number-9 shaft.
The head, shaft and grip which constitute the 10-iron 10I are designated by the reference characters 10H, 10S and 10G, respectively. The shaft 10S will be hereinafter referred to as the number-10 shaft.
Hence, the present embodiment of the golf club set is an iron shaft set including the number-5 shaft 5S, the number-6 shaft 6S, the number-7 shaft 7S, the number-8 shaft 8S, the number-9 shaft 9S and the number-10 shaft 10S.
Table 1 shows various parameters of the present embodiment of the golf club set and the golf club shaft set.
The club length L decreases (progressively decreases) as the club number increases.
The head weight WH increases (progressively increases) as the club number increases.
The shaft weight WS increases (progressively increases) as the club number increases.
The gravity center location GCL of the shaft is expressed by the percentage of the length from the tip end thereof to the center of gravity of the shaft with respect to the length of the shaft. The gravity center location GCL of the shaft is located progressively closer to the tip end of the shaft (in steps of 0.5 percent of the length of the shaft every time the club number increases by one) as the club number increases.
The grip weight WG is constant regardless of the club number.
The club weight WT increases (progressively increases) as the club number increases.
As shown in this drawing, the club moment of inertia MOIT of a golf club is defined as the sum of the moments of inertia MOIH, MOIS and MOIG of the head, shaft and grip that constitute the golf club (MOIT=MOIH+MOIS+MOIG).
The head moment of inertia MOIH is calculated by multiplying the head weight WH by the square of the length LH from the club butt end to the gravity center location of the head (MOIH=WH×(LH)2).
The shaft moment of inertia MOIS is calculated by multiplying the shaft weight WS by the square of the length LS from the club butt end to the gravity center location of the shaft (MOIS=WS×(LS)2).
The grip moment of inertia MOIG is calculated by multiplying the grip weight WG by the square of the length LG from the club butt end to the gravity center location of the grip (MOIG=WG×(LG)2).
Table 2 shows the club moment of inertia (MOI[kg/cm2]) of each golf club of the present embodiment of the golf club set.
As shown in TABLE 2, in the present embodiment of the golf club set, when one golf club is selected as a reference golf club from among all the irons, ranging from the 5-iron 5I to the 10-iron 10I, this reference golf club and any one of the remaining golf clubs satisfy the following condition (1):
0.995X<Y<1.005X (1)
wherein X designates the club moment of inertia (MOI[kg/cm2]) of the reference golf club, and
Y designates the club moment of inertia (MOI[kg/cm2]) of any one of the remaining golf clubs.
Namely, in the present embodiment of the golf club set, the club moments of inertia of the 5-iron 5I through to the 10-iron 10I are matched (united) to within a range of ±0.5 percent no matter which golf club is selected as a reference golf club from among all the golf clubs of the golf club set.
Satisfying condition (1) makes it possible to obtain a stable swing feel suitable for the player regardless of the club number.
In either case, when the upper limit of the condition (1) is exceeded or the lower limit of the same is exceed, the dispersion in the values of the club moments of inertia due to different numbers of golf clubs becomes excessively large, which makes it difficult to obtain a stable swing feel suitable for the player.
The above described functions and effects can be more prominently obtained by satisfying the following condition (1′):
0.998X<Y<1.002X (1′).
The satisfying of condition (1′) signifies that the club moments of inertia of the 5-iron 5I through to the 10-iron 10I are matched (united) within the range of ±0.2 percent no matter which golf club is selected as a reference golf club from among all the golf clubs of the golf club set.
Additionally, it can be understood from Table 2 that the following relationships are established between the head moments of inertia of the head MOIH, the shaft moments of inertia MOIS, the grip moments of inertia MOIG and the club moments of inertia MOIT of the 5-iron 5I through to the 10-iron 10I.
The grip moment of inertia MOIG is constant (or substantially constant; slight deviation is acceptable) regardless of the club number.
The head moment of inertia MOIH decreases as the golf club number increases.
The shaft moment of inertia MOIS increases as the golf club number increases.
Additionally, throughout all the numbered golf clubs, the club moments of inertia MOIT are made substantially identical by cancelling out the decrease in the head moment of inertia MOIH and the increase in the shaft moment of inertia MOIS on each numbered golf club.
Focusing on the golf club shaft set and the individual shafts, the number-5 shaft 5S through to the number-10 shaft 10S are configured so that the shaft weight increases and the gravity center location of the shaft is located closer to the tip end of the shaft as the club number increases.
To make this implementable, the present embodiment has adopted the technique of embedding, in a portion of each shaft on the tip end side, a metal cylinder and a metal foil(s), each of which increases in weight as the club number increases.
In the following descriptions, the detailed structures of the number-5 shaft 5S through to the number-10 shaft 10S will be hereinafter discussed with reference to
The number-5 shaft 5S through to the number-10 shaft 10S are each provided with prepregs P1, P2, P3, P4, P5, P6 and P7 as common elements (different in sheet length and weight), in that order from the inner layer toward the outer layer.
The prepreg P1 is a tip-end partial layer that is wound around the tip end of the shaft, and also is a 0-degree prepreg, the fiber direction of which is substantially parallel to the longitudinal direction of the shaft.
Each of the prepregs P2 and P3 is a full-length prepreg that is wound around the shaft over the full length thereof, and also is a bias prepreg, wherein the fiber directions of the prepregs P2 and P3 are symmetrical with respect to the longitudinal direction of the shaft (angled at ±45 degrees relative to the longitudinal direction of the shaft in the present embodiment).
Each of the prepregs P4, P5 and P6 is a full-length prepreg that is wound around the shaft over the full length thereof and also is a 0-degree prepreg the fiber direction of which is substantially parallel to the longitudinal direction of the shaft.
The prepreg P7 is a tip-end partial layer that is wound around the tip end of the shaft and also is a 0-degree prepreg, the fiber direction of which is substantially parallel to the longitudinal direction of the shaft.
The number-5 shaft 5S through to the number-10 shaft 10S each have a metal cylinder MC that is embedded as the innermost layer in the tip end of the shaft. The metal cylinder MC is made of a material such as iron, aluminum or tungsten. The metal cylinder MC increases in weight as the club number increases (4.95 g in the number-5 shaft 5S, 5.50 g in the number-6 shaft 6S, 6.05 g in the number-7 shaft 7S, 6.60 g in the number-8 shaft 8S, 8.25 g in the number-9 shaft 9S and 10.45 g in the number-10 shaft 10S).
The number-5 shaft 5S through to the number-10 shaft 10S are each provided between the prepreg P3 and the prepreg P4 with a metal foil MF1 as a tip-end partial layer that is wound around the tip end of the shaft.
In addition to the metal foil MF1, the number-8 shaft 8S through to the number-10 shaft 10S are each provided, between the prepreg P4 and the prepreg P5, with a metal foil MF2 as a tip-end partial layer that is wound around the tip end of the shaft.
The metal foil MF1 and the metal foil MF2 are made of a material such as copper, stainless steel or aluminum.
Each metal foil (the metal foil MF1 in the number-5 shaft 5S through to the number-7 shaft 7S, or each metal foil MF1 and MF2 in the number-8 shaft 8S through to the number-10 shaft 10S) increases in weight as the club number increases (1.07 g in the number-5 shaft 5S, 1.91 g in the number-6 shaft 6S, 2.87 g in the number-7 shaft 7S, 4.41 g in the number-8 shaft 8S, 5.99 g in the number-9 shaft 9S and 7.69 g in the number-10 shaft 10S).
According to the technique using the metal foil MF1 (and the metal foil MF2) as well as the metal cylinder MC, the shaft weight and the gravity center location of the shaft can be relatively freely set irrespective of the club number, and accordingly, the golf clubs of the entire golf club set can be made substantially uniform (matched) in club moment of inertia. The inventors of the present invention have applied for and acquired patents for such a technique (e.g., Japanese Unexamined Patent Publication No. 2012-110498, Japanese Unexamined Patent Publication No. 2013-220285, and Japanese Patent Publication No. 4,880,063).
Table 3 and Table 4 are tables corresponding to Table 1 and Table 2, showing a conventional steel-shaft golf club set.
As can be clearly understood from
Table 5 and Table 6 are tables corresponding to Table 1 and Table 2, showing a conventional carbon-shaft golf club set.
As can be clearly understood from
In contrast, in the golf club shaft set according to the present invention, the shaft moment of inertia increases as the club number increases; accordingly, the golf club shaft set according to the present invention shows characteristics completely opposite to those of the conventional golf club steel-shaft set and the conventional golf club carbon-shaft set.
Table 7 and Table 8 are tables corresponding to Table 1 and Table 2, showing the golf club set according to the second aspect of the present invention.
In the golf club set according to the second aspect of the present invention, the shaft weight increases and the gravity center location of the shaft is located closer to the butt end of the shaft as the club number increases. Additionally, by substantially increasing the increase in shaft weight on each numbered club, the numbered golf clubs of the entire golf club set are matched (united) to be substantially uniform in club moment of inertia.
In the golf club set according to the second aspect of the present invention, golf club shafts labeled with high numbers, and hence golf clubs labeled with high numbers, become excessively great in weight, and accordingly, the difference in weight between golf club shafts labeled with different numbers, and hence the difference in weight between golf clubs with different numbers, becomes excessively great.
Namely, in the golf club set according to the second aspect of the present invention, both the shaft weight and the gravity center location of the shaft are shifted by a fine adjustment amount for each club number; accordingly, golf club shafts labeled with high numbers, and hence golf clubs labeled with high numbers, can be minimized in weight compared with those of the golf club set according to the second aspect of the present invention, so that the difference in weight between golf club shafts labeled with different numbers, and hence the difference in weight between golf clubs with different numbers, can be minimized (in this respect, the golf club set according to the first aspect of the present invention can be said to be superior to the golf club set according to the second aspect of the present invention).
However, since all the golf clubs are matched (united) to be substantially uniform in club moment of inertia even in the golf club set according to the second aspect of the present invention, a stable swing feel suitable for the player can be obtained regardless of the club number.
The case where a golf club set and a golf club shaft set according to the present invention have been applied to an iron club set and an iron shaft set has been illustrated by way of example in the above described embodiments. However, a golf club set and a golf club shaft set according to the present invention can also be applied similarly to a wood club set and a wood shaft set.
The case where a golf club set and a golf club shaft set according to the present invention have been applied to six irons, specifically 5 through 10 irons and the shafts thereof have been illustrated by way of example in the above described embodiments. However, a golf club set and a golf club shaft set according to the present invention may be applicable solely to the case where a plurality of different numbered golf clubs and a plurality of different numbered golf club shafts are provided. For instance, in addition to (or instead of) six iron clubs and six iron shafts of 5 through 10 irons, five iron clubs and five iron shafts of 0 through 4 irons can all, or partially, be used.
Although the case where a metal cylinder and a metal foil(s), each of which increases in weight as the club number increases, are embedded in the tip-end side portion of the shaft of each golf club of a plurality of golf club shafts has been illustrated by way of example in the above described embodiments, an embodiment in which only one of the metal cylinder and the metal foil(s) is embedded is also possible, or another embodiment in which neither a metal cylinder nor a metal foil(s) is embedded in the 5 and 6 irons and in which at least one of a metal cylinder and a metal foil(s) each of which increases in weight as the club number increases is embedded in the 7 through 10 irons is also possible.
A golf club set according to the present invention is suitably used in the industrial field of golf club shafts, golf clubs and golf club sets.
While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.
Claims
1. A golf club set comprising different numbered golf clubs, each of which is constructed by fixing a head and a grip to a tip end and a butt end of a shaft, respectively,
- wherein moments of inertia of said grips of respective said golf clubs are substantially uniform regardless of said numbers of respective said golf clubs;
- wherein moments of inertia of said heads of respective said golf clubs decrease as said numbers of respective said golf clubs increase;
- wherein moments of inertia of said shafts of respective said golf clubs increase as said numbers of respective said golf clubs increase;
- wherein moments of inertia of said golf clubs are made substantially the same by cancelling out the decrease in said moments of inertia of said heads and the increase in said moments of inertia of said shafts; and
- wherein said shafts of said golf clubs increase in weight, and respective gravity center locations of said shafts are located closer to said tip ends of said shafts, as said numbers of said golf clubs increase.
2. The golf club set according to claim 1, wherein, when one golf club is selected as a reference golf club from said golf clubs of said golf club set, said reference golf club and any one of remaining golf clubs of said golf club set satisfy the following condition (1):
- 0.995X<Y<1.005X (1)
- wherein X designates a club moment of inertia (MOI[kg/cm2]) of said reference golf club, and
- Y designates a club moment of inertia (MOI[kg/cm2]) of any one of said remaining golf clubs.
3. The golf club set according to claim 1, wherein at least a portion of each said golf clubs of said golf club set comprises, on said tip end side of said shaft, one or both of a metal cylinder and a metal foil which increase in weight as said numbers increase.
4. The golf club set according to claim 1, wherein said golf clubs of said golf club set comprise at least six irons ranging from a 5-iron through to a 10-iron.
5. The golf club set according to claim 2, wherein at least a portion of each said golf clubs of said golf club set comprises, on said tip end side of said shaft, one or both of a metal cylinder and a metal foil which increase in weight as said numbers increase.
6. The golf club set according to claim 2, wherein said golf clubs of said golf club set comprise at least six irons ranging from a 5-iron through to a 10-iron.
7. The golf club set according to claim 3, wherein said golf clubs of said golf club set comprise at least six irons ranging from a 5-iron through to a 10-iron.
Type: Application
Filed: Mar 7, 2016
Publication Date: Mar 16, 2017
Inventors: Masaki Wakabayashi (Saitama-shi, Saitama), Yoshihito Kogawa (Saitama-shi, Saitama)
Application Number: 15/309,053
