CA2086421A1

CA2086421A1 - Golf club

Info

Publication number: CA2086421A1
Application number: CA002086421A
Authority: CA
Inventors: Mitsuhiro Saso
Original assignee: Individual
Current assignee: HIMEJI LODGE HAKUBA KK
Priority date: 1991-05-01
Filing date: 1992-03-13
Publication date: 1992-11-02
Also published as: EP0773046A1; DE69225860D1; DE69225860T2; EP0537358A1; WO1992019327A1; KR930701212A; KR970007191B1; TW365179U; EP0537358A4; EP0537358B1

Abstract

2086421 9219327 PCTABS00017 A golf club for improving the flying distance by removing phenomenon of pulling the shaft occurring as a reaction to phenomenon of prostrated toe liable to occur particularly to a skilled player enjoying a high head speed and further improving the head speed, and for improving the directional stability of a hit ball by removing phenomenon of prostrated toe and changing the design such as in the face resulting therefrom, the golf club being characterized in that the center of gravity of the head is shifted from the toe end to the shaft end by modifying the head shape by decreasing the volume of the head by a certain amount at the toe end on the rear side thereof and increasing the head volume at the shaft end on the rear side by an amount equal to the amount decreased, thereby reducing the rotational radius of the head about a vertical line, as a rotational center line, when the golf club is suspended at the upper end of the shaft thereof. Furthermore, with a metal wood club, a head is provided with a face which comprises a spherical face formed in such a manner that the curvature in the transverse width direction becomes substantially equal to that in the vertical width direction. Moreover, with an iron club, the shape of the back of the face portion is formed by extending the central axis a of the above hosel substantially to a position where it passes through in the transverse direction, and the increase in thickness of the back of the neck portion is effected by moving a part of the weight at the toe end.

Description

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TITLE OF THE INVENTION
Golf Club FIELD OF THE INVENTION
The present invention relates to a golf club by which the directional stability and flight distance of a shot ball can be improved.
PRIOR ART
In a conventional wooden club, as well as to a metal wood club, a head is in such a shape that, as shown by two dashed line in Fig. 1, it gradually expands from a shaft side to a toe sideO The center of gravity of the head is set at a position inclined toward the toe side rather than the center of the projection plane of the head, thereby the head speed of the golf club may be increased at the time of impacting on the ball.
Also in a conventional golf club of an iron type, according to the similar theory, an end of the bacX side of a club face part is, when seen from a plane, smoothly connect~d to the hosel~ through a neck part, forming a curve (See dashed line A in Fig. 6) and thus the center of gravity ~, of the club is set at a position slightly inclined toward a toe side.
However, when the center of gravity of the head inclines toward the toe side, as shown by two dashed line in Fig. 2, ; 25 and when the head B is rotated with holding an end A of the , ~ .

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2 ~ 2 1 club shaft, a radius R0 of the rotation, with its cPnter line of the rotation positioned at the vertical line made by suspending an upper end of the shaft, increases. Therefore, the metal wood club and the iron club, as shown in Figs. 3 ~A) and ll(a), respectivaly, are apt to cAuse covering motion (which means the phenomenon that the toe side goes fast than the shaft side as if the toe side rotates around the shaft side) at each head toe side just before impacting.
For the purpose of inhibiting a hook flying of the shot ball, caused by the covering motion, in the metal wood club, as shown by two dashed line in Fig. 1, a head face surface usually has such a shape that the shaft side expands slightly more forward than the toe side. Accordingly, curvature along -~ the transverse direction of the face surface and curvature ~ 15 along longitudinal direction of the face surface are not the ; same; usually curvature along longitudinal direction is larger than that along the transverse direction.
On the other hand, as shown in Fig. 10, the covering motion is not ~he only problem in the iron club; that is, the center of gravity of the iron club slightly inclines toward the toe side in the club face part, therefore for advanced -~ golfers whose down swings are faster than those of beginners, a toe down phenomenon, in which the neck part is twisted ; downwardly ~by an accelerated motion applied to the head and '~

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208~21 thus the toe side of the club face part tends to be lowered, resulting in duff shot.
Accordingly, for the purpose of overcom.ing the de~ects of the conventional club h~ad, the inventor, as a result o~
his sharp research, has converted the basic concept of designing the club head to a new one in order to provide a golf club head by which improvement in ~he directional stability and flight distance of the shot ball can be realized. That is the object of the present invenkion.
The present invention has been completed on the inventive concept found by us that due to the property of the sling motion of the club head round the gravity center thereof, in which a heavier part goes forward and a lighter part does not catch up with the heavier part in a manner that the h~avier part and the lighter part rotate around the yravity center axis, the conventional club head is subjected not only to the above-mentioned covering movement but also to a pull-back phenomenon in the shaft side as a reaction of the covering movement, accordingly resulting in substantial decrease of the speed of the head. The present invention is, therefore, to -. provide a golf club which head is formed in such a manner that the amount of a shaft side is increased as much as the amount ~ of a head toe side i~ decreased so as to shift the center of - ; gravity of the head toward the shaft side and a radius of a ~ 25 rotation, with its center line of the rotation positioned at , .
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a vertical line made by suspending an upper end of a shaft, is decreased.
Mere shift of the center of gravity o~ the head toward the sha~t side is not enough to overcome the covering motion of the head; at the same time, the weight balance o~ the head must be maintain~d. There~ore, it is advantageous to increase the amount of the shaft side in the head as much as that of the toe side decreases so as to maintain the weight balance of the head. Due to this, the center of gravity of the head lo usually inclines toward the shaft area by the amount having been shifted.
- According to the present invention, as shown by solid line in Fig. 2, since the center of gravity of the head inclines toward the shaft side, when the head is rotated by holding the end of the club shaft, the radius SLAYING of the rotation is smaller than the conventional radius R0 of the rotation. Moreover due to the increased amount of the shaft side, with use of the sling motion in which the heavier part tends to go forward and the lighter part tends to be pulled ~ackward just before impact, as shown in Fig. 3(b), it is difficult to cause the covering motion apt to take place in - the toe side and the~draw phenomenon apt to take place in the , shaft side, which rssults in the improvement in the speed of ,' the head upon giving the impact.
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In applying the present invention to a metal wood club, the curvatures along the transverse direction and along the longitudinal direction of the face surface are substanti~lly the same. Since the flight direction of the shot golf ball is dominated by both curvatures along the transverse direction and along the lon~itudinal direction of the ~ace surface of a point where the impact is given, when the curvatures are not the same, the flight direction is not controlled to a desired direction. In the present invention, however, the covering lo motion of the head at the time o~ the impact is inhibited by shifting the center of gravity of the head toward the shaft side, resulting in that the head face surface is formed by a sphere having substantially the same curvatures along both directions of the face surface, which spherical face is most suitable for giving an impact causing the shot ball con-trolled. Moreover, since it is difficult to cause the covering motion of the head upon giving an impact, the shot ball tends to direct to the extension of the line connecting the center C of spherical body defining thP spherical face and the position where the impact was given, by which superior directional stability of the shot ball is ensured.
In applying the present invention to an iron club, it is pre~erable to form a back side 122 of a club face part 102 by extendiny the back side 122 until it passes through the center axis {a) of the hosel part 103 (See Fig. 6), and moreover it , : ~ ,:' '' -.

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2~3~21 is preferable to increase thickness A of the back side 122 of a neck part 4 by shifting a part of the weight of the toe side ~ (See Fig. 8). Due to this, although the desi~n is out of the conventional common knowledge in the light of the conventional toe-heel balance, the center vf yravity is located at, or almost at the intersection point of diagonals passing across the club face part, by which good balance is maintained, return Oe the t~e in hitting a ball is suppressed by 70% and the cause for duffing can be solved (See Fig. 11).
Therefore secure down strokes can be ensured. Moreover in the light of the dasign, thickness of a blade can be increased, by which sufficient spinning shot ball can be made.
Further, since the center of gravity is located at, or ; almost at the intersection point of diagonals passing across the club face part, different from the conventional iron, a toe down phenomenon apt to take place upon giving an impact ~` can be overcome (See Fig. 10) and the weight distribution suitable for th~ motion going in and out from a heel is completed, resulting in preventation of mistakes caused by duffing.
~ In the prPsent invention, when the club face part 2 is - designed so as to slightly open by about 1.5 ~against the ball upon addressing, the defect of the conventional club, in which the ~ead easily turns after the impact and therefore golfers are apt to duff (See Fig. ll(a)), can be ovércome. Namely, . .

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2 ~ 2 1 an impact is given in a slightly open position and immediately after this, the position becomes square and then the head turns little by little, which makes the sho~ ball to fly in a high draw trajectory (See Fig. ll(b)).
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plane view comparing the plane shape of a metal head according to the present invention with that of a conventional metal head.
Fig. 2 is a comparative view showing sling motions of wooden clubs with the metal head according to the present invention and with the conventional metal head.
Fig. 3(a) is an explanatory view showing motion of the conventional metal head before and after an impact.
Fig. 3(b) is an explanatory view showing motion of the metal head according to the present invention before and after an impact.
Fig. 4 is a perspective view showing the idea of ;, designing a face surface of the metal head according to the present invention.
Fig. 5 is a rear view showing a head part of an iron club according to the presPnt invention.
- Fig. 6 is a sectional view along - line in Fig. 5.
~sc~ematical perspective view showing the club according , to the pr sent invention.

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2~85g21 Fig. 8 is a rear view showing an iron club according to another example of the present invention.
Fig. g is a front view showing a position of the center of gravity according to the weight distribution of the present invention.
Fig. 10 is a comparative explanatory view showing a toe-down phenomenon in a club according to the present invention (solid line) and in a conventional club.
Fig. 11 is a comparative explanatory view showing a covering motion in an iron club according to the present invention (a) and in a conventional club (b).
PREFERRED EMBODIMENT
~The present invention will now be explained in detail, 1in which the present invention is applied to a metal wood club.
Fig. 1 is a plane view illustrating a projected plane of ~ ~ .
a metal head according to the present invention, comparing with a conventional metal head. A metal head 1 is a hollow casting, having a ~spherical face 2 and a hosel part 3 connecting with an unshown shaft. The weight distribution 11 of a toe side is shifted to the back of a shaft side 12 and expanded ~See an extent of obligue line). On the whole, the distribution of the amount is not s~mmetrical, but leans -toward the shaft area rather than th~ toe area. Therefore ~esides the center of gravity G~ the head shifts from G0 to ' - ' ~ .
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9 2~86~21 the shaft side Gl, the distribution of the amount in the shaft side is incrèased. As a result, the superior weight distribu-tion which, at the moment of giving an impact, suppresses the covering motion in the toe side and the draw phenomenon in the shaft side, can be obtained.
As ~or the face sur~acè 2, as shown in Fig. 4, the curvature R along the transverse direction and the curvature ` R along the longitudinal direction are unified and the ~ace 2 surface is so designed that it forms a part of a sphere with radius R round a center C as illustrated. The hosel part 103 obliquely protrudes upward frcm a position adjacent to the face surface translated in parallel to the center of th~
sphere. The loft angle of the face surface generally falls on the range from about ~- 12 and both curvatures along the transverse and longitudinal directions of the face are selected ~rom the range from 9 - 12R so that they are the same. Use of such a golf club makes a golf ball and the face surface collide with each other at the time of impact as if a small ball and a large ball collided with each other and the - 20 shot ball is directed to the line extPnding a radius connect-j ing the spherical center C and the position where the impact was given.
Now the present invention will be explained, in which it is applied to an iron club head.

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Figs. 4 to 7 illustrate an iron golf club according to an example of this invention. A club head 101 is formed by integrally connecting a club face part 102 and a hosel part 103 at a neck part 104. The club head lol is integrally manufactured with use of an iron material or a copper material by means of forging or casting and polished ~or finishing.
A fixed hole 130 is formed along the longitudinal direction of the hosel part 103. A shaft 105 i5 engaged with and fixed to the fixed hole 130 and at the upper side of the lo shaft, a grip (not shown) is provided.
: The club face part 102 comprises a face 120 made open by 1.5 from a square, a sole 121 and a back side 1~2. As shown in Fig. 5, the back side 122 is ~ormed in such a manner that the back side 122 i5 extended to a position passing through - 15 the center axis (a) of the hosel part 103 and connected to the hosel part 103 through an end surface. The thickness of the back side 122 of the club face part 102, therefore, is increased and compared with the shape of a conventional club head, the neck part is made much smaller. As a result, the - 20 weight of the neck part is increased and, as shown in Fig. 9,- the center of gravity of the club head i5 located at or adjacent to an i~tersection point of diagonals of the face part.
Accordingly, when a golfer with this club adresses, even though the club ~ace part 102 is placed in a s~uare position, .

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2086~21 it looks slightly open. The back side 122 of the club fa~e part 102 is extended to a position passing across the center axis (a) of the hosel part 103. The neck part swel].s and further the center of gravity of the club ~ace part 10?. i~
positioned at the intersection point of the diagonals and slightly inclines toward a heel side to stabilize the club face part 102. When the club is swung under these conditions, it is easy for a golfer to give an impact to a ball in a square position and fly the ball in a straight direction without a hook or a slice. Moreover even when advanced golfers swing downward at a high speed, since good rigidity around the hosel part 103 is given and the center of gravity of the club face part 102 is located at the intersection point ~` of the diagonals so as to slightly incline toward the heel side, a toe-down phenomenon hardly takes place and it results in a smooth impact without duffing.

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Claims

WHAT IS CLAIMED IS:

1. A golf club characterized in that; a head is formed in such a manner that the amount of a shaft side is increased as much as the amount of a head toe side is decreased so as to shift the center of gravity of the head toward the shaft side and a radius of a rotation, with its center line of the rotation positioned at a vertical line made by suspending an upper end of a shaft, is decreased.

2. The golf club of a metal wood type, in which the head has a spherical surface with substantially the same curvatures-along the transverse direction thereof and along the longitu-dinal direction thereof.

3. The golf club of an iron type, in which the head has aback side of a face part formed in such a manner that the back side is extended to a position passing through a center axis (a) of a hosel, and the thickness of the back side of a neck part is increased by shifting a part of weight of a toe side of the club head.

4. The golf club of an iron type as claimed in claim 3, in which the face surface is formed in a slightly open position against the ball to be set up at the time of addressing.