Patent Application
20060111202
1. Field of the Invention
The present invention relates to a golf club.
2. Description of the Related Art
Golf clubs are classified roughly into a wood type, an iron type and a putter type. The wood-type golf club is used to give an initially low shot and hit a long ball, while the iron-type golf club is used to give an initially high shot to hit the ball with a backspin, taking aim at a target position from above, and the putter is used on a green.
Among the iron-type golf clubs, a pitching wedge type is used to hit a shot for giving a carry of up to about 110 yards (101 m), while a sand wedge type designed mainly for playing on a banker is used to hit a shot for giving a carry of up to nearly 80 yards (73 m).
In these wedge types, a tilt angle of a face surface (a golf ball hitting area), i.e., a loft angle is set at approximately 52 to 56 degrees and a tilt angle of a shaft, i.e., a lie angle is set at nearly 64 degrees.
In each of these iron-type golf club heads, there are provided a sole face acting as a ground contact surface in a lower portion thereof and a face surface acting as a golf ball hitting area in front thereof. The face surface is formed with score lines and further the head is formed with a toe 9, a heel and a hosel for fitting a shaft thereto, and a depressed portion at a rear, as disclosed in Japanese unexamined patent publication No. 7-255879 along with its FIG. 1, FIG. 7.
For an approach shot when the golf ball is shot to be carried on the green, a pitch-and-run shot and a pitch shot are used. These shots are golf ball hitting methods for hitting the golf ball with a larger magnitude of the backspin (a reverse spin) to give a comparatively high shot, thus stopping the golf ball on the green. Particularly, the pitch shot method aims at giving the golf ball a strong backspin, so that the golf ball is dropped short of a cup on the green and then immediately stopped.
Heretofore, the face surface is formed with multiple small grooves called score lines as a means for applying a backspin to a golf ball at the time of hitting it. The assignee of the present application has ever filed applications (e.g., Japanese unexamined patent publication No. 2003-199851) pertaining to a golf club head, in which the score lines capable of applying a strong backspin to a ball are provided on the face surface by forming score lines on the face surface by press working, and then flattening the face surface by machining or press working to thereby sharpen the edge angles of the score lines so as to make the golf ball easy to be caught in the score lines, so that an effective spin can be applied to the golf ball.
Restrictions are, however, imposed on the face surface and the score lines by the Golf Rules due to their large influences on spin imparting performance. Therefore, there has not only been a limitation in the improvement of the edge portions of the score lines but also there have been possibilities that the golf ball may be cut by such sharp edge portions of the prior art at the time of striking the same.
Further, whilst in the case that the angles of the edge portion of the score lines are formed sharp in accordance with the prior art, the golf ball becomes easy to be caught in the edge portions so that a backspin will be easily applied thereto, there remains, however, such a problem that not only the sharpness of each score line edge is decreased slightly at every shot but sands or the like will get into the score lines especially in the case of a bunker shot to make it impossible to ensure the sharpness of the edge portions.
To eliminate the above problems, it is therefore, an object of the invention to provide a golf club having a head with a face surface formed with score lines and a shaft connected with the head, which enables a strong backspin to be applied without the aid of the face surface having the score lines.
A first aspect of the present invention is a golf club comprising: a head having a sole face provided in a lower portion that acts as a ground contact surface, a face surface acting as a ball striking surface, provided on a front of said head with a certain loft angle, a shaft connecting portion on one side thereof, score lines formed on the face surface of said head, and a shaft connected to said shaft connecting portion, wherein
a height of the center of gravity of said head is greater than a radius of a golf ball, the height of the center of gravity of said head being defined as a distance from a horizontal plane flush with the sole face of said head to the center of gravity of said head.
Thus, the center of gravity of the head is positioned in a higher position than the center of a golf ball at the time of hitting a shot, and thus the face surface is allow to rotate downward or clockwise due to the ball impact thus imparted, so that so-called gear effect is generated to thereby be able to accelerate the backspin of the ball.
A second aspect of the present invention is a golf club as set forth in the first aspect, wherein an upper protrusion and a lower protrusion are provided spacedly rearwardly of upper and lower positions of said head, respectively such that a distance between a rear end of said upper protrusion and said face surface is greater than a distance between a rear end of said lower protrusion and said face surface.
Accordingly, the height of the center of gravity of the head measured with reference to the horizontal plane flush with the sole surface of the head is arbitrarily adjustable due to the adjustment of the weight distribution between the upper and lower protrusions.
A third aspect of the present invention is a golf club set forth in the first aspect, wherein an upper protrusion and a lower protrusion are provided spacedly rearwardly of upper and lower positions of said head, respectively, and the lower protrusion includes a depressed portion formed on an upper surface thereof.
Accordingly, it is possible for the lower protrusion to decrease the weight corresponding to the depressed portion, thus enabling the position adjustment of the center of gravity of the head even more easily.
The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which:
Next is a detailed description of preferred embodiments with reference to the appended drawings. It should be noted that the embodiments described below shall not be construed as limiting a subject matter of the present invention set forth in the claims, and that all the structures described below are not indispensable requisites for the present invention.
The head 2 is formed from steel or a combination of steel and other materials. In the present embodiment, the head formed from steel is shown. The head 2 is formed with a sole face 6 acting as a ground contact surface in a lower portion of the head, a heel 7 at one side of a lower portion of the head, a top 8 in an upper portion of the head and a toe 9 at the other side of the heel 7. Further, score lines 10 formed by small grooves are arranged spacedly on the face surface 1. The face surface 1 has a loft angle δ (delta) relative to a perpendicular line to a horizontal plane 6A flush with the sole face 6.
The head 2 is composed of four main weight components, i.e., a face surface portion 11, a rear lower portion 12, a rear upper portion 13, and the shaft connecting portion 3, which are integrated together to form the head 2. The face surface portion 11 essentially comprises the face surface 1 and has substantially a plate shape, including at least the face surface 1, a forepart of the sole surface 6, the top 8, the toe 9 and the heel 7. The rear lower portion 12 is formed with a lower protrusion 15 that extends rearwardly of the face surface portion 11 so as to construct a rear portion of the sole face 6. An upper surface 16 of the lower protrusion 15 is arranged so as to be substantially orthogonal to the surface of the face surface 1, at a lower position than nearly half a height A of the face surface 1, said height A being measured with reference to the sole face 6 or a horizontal plane 6A flush with the sole face 6. It should be noted that the inside of the upper surface 16 is formed with a depressed portion 17 that is formed in an undercut-shaped manner. In the meantime, the horizontal plane 6A of the sole face 6 is determined on the basis of a ground contact surface at the time of addressing a ball with the golf club.
On the other hand, the rear upper portion 13 is provided so as to extend from the top 8 and the toe 9 to thereby form an upper protrusion 18 rearwardly of the face surface portion 11. The upper protrusion 18 is solid and its lower surface 19 is arranged so as to be substantially orthogonal to the surface of the face surface 1, at a higher position than nearly half the aforesaid height A of the face surface. As a result, in the rear central portion of the face surface portion 11, i.e., in a region located in nearly half the height A of the face surface, a cavity 20 is formed as a space sandwiched between the upper surface 16 and the lower surface 19 so as to extend rearwardly of the face surface portion 11. In the meantime, it should be noted that the face surface portion 11, the rear lower portion 12, the rear upper portion 13 and the shaft connecting portion 3 are not to be arranged with any specific or clear borderline and thus they are to be all arranged in a seamless manner.
In addition, a maximal backward protruding length of the upper protrusion 18 in the rear lower portion 13, i.e., a distance C between a rear end 18A of the upper protrusion 18 and the surface of the face surface 1 is made larger than a maximal backward protruding length of the lower protrusion 15 in the rear upper portion 12, i.e., a distance B between a rear end 15A of the lower protrusion 15 and the surface of the face surface 1 (B<C). Thus, the volume or eventually the weight of the rear lower portion 12 is made less than the volume or eventually the weight of the rear upper portion 13. As a result, a height D of the center of gravity 21 of the head 2 measured with reference to the sole face 6 or the horizontal plane 6A of the sole face 6 is formed larger than that of the center 23 of a golf ball 22 to be hit by the face surface 1. Namely, the shortest length between the center of gravity 21 of the head 2 and the sole face 6 or the horizontal plane 6A of the sole face 6 is greater than a radius E of the golf ball 22. Since the golf ball 22 is required to have a diameter of 42.67 mm according to the current Golf Rules, the height (distance) D is set larger than the radius E of 21.335 mm. In the meantime, the height D does not exceed the height A of the face surface.
In a preferred form of the invention, the height D may be set at 23 mm, for example. This means that the center of gravity 21 of the head 2 is raised by about 13 to 16% as compared with the conventional ones since they were in the order of 19.8 mm or 20.4 mm.
Further, the center of gravity 21 arranged in a nearly central portion of a width direction of the face surface 1 is arranged in a position anterior to the face surface 1, but posterior to a distal end of the sole face 6 (i.e., a lower end of the face surface 1).
Next is a description of a function of the above-structured golf club. In the case of using a wedge-type golf club among the above-described iron-type golf clubs to hit a pitch shot, the downswing of the golf club is carried out so that the head 2 is moved in an arc orbit in a manner thrusting into the underneath of the golf ball 22. At that moment, the face surface 1 contacts the golf ball 22 so as to get into the underneath thereof and then hits the golf ball 22. As a result, as shown in
Further, at the time of hitting the golf ball 22, the height D of the center of gravity 21 is larger than the radius E of the golf ball 22 and further the center of gravity 21 of the head 2 is provided in a position anterior to the face surface 1. Hence, as the center of gravity 21 thereof is located higher than the center 23 of the golf ball 22 at the time of hitting a shot, the golf ball 22 is allowed to fly comparatively low at an initial stage. More specifically, an initial flying-out angle θ (theta) of the golf ball 22 is diminished. Thus, the golf ball 22 becomes easy to be caught in the edge portions of the score lines 10 to be able to effectively apply backspin to the same. On the contrary, if the height D is smaller than the radius E of the golf ball 22, then the center of gravity 21 would be located lower than the center 23 of the golf ball 22. Hence, the initial flying-out angle θ would be increased so that the golf ball 22 become hard to be caught in the edge portions of the score lines 10, thus making it difficult to apply the backspin thereto.
Thus, at the time of hitting a pitch shot, the golf ball 22 is allowed to fly initially low to fall on a green with a strong backspin being applied thereto, thereby permitting the golf ball 22 to stop at a desired fall point or in the vicinity of that point.
According to the foregoing embodiment, there is provided the golf club comprising: the head 2 having the score lines 10 formed on the face surface 1 and the shaft 4 connected therewith, wherein the height D from the sole face 6 of the head 2 or the horizontal plane 6A of the sole face 6 to the center of gravity 21 of the head 2 is greater than the radius E of the golf ball 22. Consequently, at the time of hitting the shot, when the golf ball 22 strikes the head 2, then the face surface portion instantaneously withdraws in the sole face 6 side while it tends to erect the face and turns. Hence, the golf ball rubbed against the face surface 1 is spun up in a direction reverse to the rotation of the face surface 1, so that the backspin can be accelerated by the so-called gear effect.
Further, the upper protrusion 18 and the lower protrusion 15 are provided spacedly rearward of the upper and lower portions of the head 2, respectively. The distance C between the rear end 18A of the upper protrusion 18 and the surface of the face surface 1 is formed greater than the distance B between the rear end 15A of the lower protrusion 15 and the surface of the face surface 1. Hence, as the center of gravity 21 in the head 2 is located on comparatively upper side, the height D from the sole face 6 of the head 2 or the horizontal plane 6A of the sole face 6 to the center of gravity 21 of the head 2 can be arbitrarily adjusted by the adjustment of weight distribution between the upper protrusion 18 and the lower protrusion 15. Besides, the moment of inertia in a vertical direction can be increased, so that a vertical jiggling at the time of hitting the shot is reduced to be able to improve the stability of a golf ball flying direction.
Further, the depressed portion 17 is formed on the upper surface 16 of the lower protrusion 15. Hence, the weight corresponding to the volume of a space inside the depressed portion 17 can be reduced in the lower protrusion 15, so that position adjustment in the center of gravity 21 can be more easily carried out.
Furthermore, by using, the wedge type golf club with its center of gravity thus positioned, approach shots from around the green can be precisely carried out.
Moreover, the height D is equal to or greater than 21.335 mm, and thus, the height D greater than the radius of the golf ball 22 prescribed under the current Golf Rules can be ensured.
Further, the center of gravity 21 of the head 2 is provided in the position anterior to the face surface 1. Hence, an initial flying-out angle θ (theta) of the golf ball 22 is decreased and thus the golf ball 22 becomes easy to be caught in the edge portions 10A of the score lines 10, so that even when a shot is hit at a bunker or the like with a likelihood that the score lines 10 are prone to be clogged with sands, the backspin can be applied effectively to the golf ball 22.
As described above, the golf club according to the present invention is applicable to various golf clubs such as other iron-type or wood-type golf clubs.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP 2004-341176 | Nov 2004 | JP | national |
