Wood type golf club

A wood type golf club having a club head provided with a sole at the bottom portion thereof, a ball striking face at the front side thereof and a hosel at the heel side thereof, and a club shaft joined to the hosel of the club head, characterized in that a face angle .theta..sub.1 measured on the basis of a direction square with the direction in which a ball is to be driven thereby, toward the side of a closed face of the club head is set to 0.degree.-5.degree. closed face, a lie angle .theta..sub.2 defined as an angle of inclination of the axis of the club shaft with respect to a horizontal line and measured with the sole of the club head contacting a horizontal ground surface being set to 58.degree.-62.degree., an angle of center of gravity .theta..sub.3 defined as an angle which is formed between an extension line of the face of the club head and a straight line crossing the axis of the club shaft at right angles thereto when the club shaft is placed on a horizontal table so that the club head is directed downward therefrom freely, viewing from the side of the sole along the axis of the club shaft being set to 27.degree.-33.degree..

BACKGROUND OF THE INVENTION 
This invention relates to a wood type golf club, and more particularly to a 
wood type golf club which is suitable especially for beginners or golfers 
having a low head speed, and which is capable of restraining the 
occurrence of the curving of a driven ball to the right of a right-handed 
player, i.e. the occurrence of a so-called slice. 
Since a wood type golf club is used generally for the purpose of obtaining 
a longer flying distance of a ball, the volume of a head thereof is larger 
than that of a head of an iron golf club, and the length of a shaft of the 
former golf club also larger than that of a shaft of the latter golf club. 
Therefore, when, especially, for example, a right-handed beginner or a 
right-handed golfer having a low head speed addresses or strikes a ball 
with a wood type golf club, the face of the golf club is opened outward, 
so that a driven ball curves to the right of the player, i.e., a so-called 
slice tends to occur frequently. 
With a view to eliminating these inconveniences, an improved wood type golf 
club has been proposed in which a face angle of the club head measured on 
the basis of a direction square with the direction in which a ball is to 
be driven thereby, a lie angle, i.e. an angle of inclination of the club 
shaft measured with the whole surface of the sole of the club head 
contacting the ground surface, and an angle of center of gravity which is 
defined as an angle formed between an extension line of the face of the 
club head and a straight line passing the axis of the club shaft at right 
angles thereto, and which is measured with the club shaft placed on a 
horizontal table so that the club head is directed downward therefrom 
freely are regulated independently of one another. The face angle, lie 
angle and angle of center of gravity generally adopted of a wood type Golf 
club produced so as to eliminate the occurrence of a slice mentioned above 
are 0.degree.-2.degree. toward the side of a closed face, 
55.degree.-58.degree. and 18.degree.-23.degree. respectively. However, 
such a conventional slice-preventing wood type golf club is designed 
mainly for advanced and intermediate class golfers, and, when a beginner 
or a golfer having a low head speed drives a ball with this golf club, a 
slice still tends to occur. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a wood type golf club 
capable of restraining the occurrence of a slice, i.e. the rightward 
curving of a ball driven by a right-handed player with the golf club. 
Another object of the present invention is to provide a wood type golf club 
which reduces a tendency of causing, especially, a beginner and a golfer 
having a low head speed to have a slice. 
A wood type golf club which achieves these objects of the present invention 
has a club head provided with a sole at the bottom portion thereof, a ball 
striking face at the front side thereof and a hosel at the heel side 
thereof, and a club shaft joined to the hosel of the club head, and is 
characterized in that a face angle .theta..sub.1 measured on the basis of 
a direction square with the direction in which a ball is to be driven 
thereby, toward the side of a closed face of the club head, a lie angle 
.theta..sub.2 defined as an angle of inclination of the axis of the club 
shaft with respect to a horizontal line and measured with the sole of the 
club head contacting a horizontal ground surface, and an angle of center 
of gravity .theta..sub.3 defined as an angle which is formed between an 
extension line of the face of the club head and a straight line crossing 
the axis of the club shaft at right angles thereto when the club shaft is 
placed on a horizontal table so that the club head is directed downward 
therefrom freely, viewing from the side of the sole at right angles to the 
axis of the club shaft are set to: 
0.degree..ltoreq..theta..sub.1 .ltoreq.5.degree. 
58.degree..ltoreq..theta..sub.2 .ltoreq.62.degree. 
27.degree..ltoreq..theta..sub.3 .ltoreq.33.degree. 
Since the face angle, lie angle and angle of center of gravity of the wood 
type golf club are set in this manner relatively to one another so that 
all of them satisfy these formulae, it becomes possible that even a 
beginner of golf and a golfer having a low head speed reduce a trend of 
the occurrence of the curving of a driven ball to the right of the players 
in case of the right-handed. A wood type golf club, in which, especially, 
a hosel and a club shaft are joined together with a crank type connecting 
member, having a combination of such angles enables this slice-reducing 
effect to be displayed remarkably.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In a wood type golf club W shown in FIG. 1, a reference numeral 1 denotes a 
club head, and 2 a club shaft. The club head 1 has a sole 1a at the bottom 
portion thereof, a ball striking face 1b at the front side thereof, and a 
hosel 1c at the heel side thereof. A reference numeral 1d denotes score 
lines consisting of grooves formed in the face 1b. A crank-like bent 
connecting member 3 is fixed to the hosel 1c of the club head 1, and one 
end of the club shaft 2 is joined firmly to the club head 1 via this 
connecting member 3. A reference numeral 5 denotes a grip fitted around 
the other end portion of the club shaft 2. 
In the wood type golf club according to the present invention formed as 
described above, a face angle of the club head measured on the basis of a 
direction square with the direction in which a ball is to be driven, i.e. 
a face angle .theta..sub.1 defined as an angle of inclination of the face 
1b with respect to a line G--G, which crosses at right angles an intended 
line of flight F, as shown in FIG. 2 is set to 0.degree.-5.degree. toward 
a closed face. A lie angle .theta..sub.2 defined as an angle between the 
axis M--M of the club shaft 2 and a horizontal surface 6 and measured with 
the sole 1a of the club head 1 contacting the horizontal surface 6 as 
shown in FIG. 1 is set to 58.degree.-62.degree.. An angle of center of 
gravity .theta..sub.3 defined as an angle which is formed between an 
extension line Y--Y of the face 1b of the club head 1 and a straight line 
X--X crossing the axis of the club shaft 2 at right angles thereto when 
the club shaft 2 is placed on a horizontal table 4 with the club head 1 
projected outward therefrom and directed downward freely, viewing from the 
side of the sole along the axis of the club shaft, i.e., in the direction 
of an arrow A as shown in FIGS. 3 and 4 is set to 27.degree.-33.degree.. 
When the face angle .theta..sub.1 is over 0.degree. open face, or when the 
lie angle .theta..sub.2 is smaller than 58.degree., or when the angle of 
center of gravity .theta..sub.3 is smaller than 27.degree., a driven ball 
becomes liable to fly out to the right of a right-handed golfer, and the 
tendency of the occurrence of a slice cannot be down satisfactorily. When 
the face angle .theta..sub.1 is larger than 5.degree. closed face, or when 
the lie angle .theta..sub.2 is larger than 62.degree., or when the angle 
of center of gravity .theta..sub.3 is larger than 33.degree., a driven 
ball becomes liable to fly out to the left of a right-handed golfer, i.e., 
a hook tends to occur. 
Thus, according to the present invention, by setting the face angle 
.theta..sub.1 of the club head 1, lie angle .theta..sub.2 and angle of 
center of gravity .theta..sub.3 of the wood type golf club W 
interdependently and systematically, the occurence of a slice can be 
restrained. In case of right-handed golfer, the occurence of the curving 
of a driven ball to the right can be going down and in case of left-handed 
golfer, the occurence of the curving of a driven ball to the left can be 
getting down. Especially, a beginner of the golf and a golfer having a low 
head speed can reduce the frequency in the occurrence of a slice. 
Regarding the setting of the face angle, lie angle and angle of center of 
gravity, the crank-shaped connecting member 3 is preferably offset at its 
club shaft-side portion to the side of a toe of the club head along an 
extending direction of the face 1b. A distance by which the club 
shaft-side portion of the connecting member 3 is offset, i.e. a distance L 
shown in FIG. 5 between the axis M--M of the club shaft 2 and a tangential 
line N--N drawn in parallel with this axis so as to pass a heel side end 
of the club head 1 may be set within 16 mm. More preferably, it may be set 
to 12-16 mm. This enables a position of fixing the club shaft 2 to the 
club head 1 to be set closer to the center of gravity of the club head 1, 
and the club head to meet a ball easily. Consequently, a slice restraining 
effect can be achieved further and the directional stability of a driven 
ball can be improved moreover. 
The present invention will now be described more concretely. 
A wood type golf club (Present Example) according to the present invention 
consisting of the structure of FIG. 1 and a conventional wood type golf 
club (Conventional Example) having no connecting member were made with the 
angles .theta..sub.1, .theta..sub.2, .theta..sub.3 and distance L set as 
shown in Table 1. These golf clubs were tested by three golfers under the 
following conditions, and the results of determination of the rates of 
occurrence of slice are shown in Table 2. 
1. Golfers' career: 
(a) Beginner A: Less than 1 year's experience, 50 years old (male), head 
speed of 37 m/sec. 
(b) Beginner B: Less than 2 years' experience, 35 years old (male), head 
speed of 43 m/sec. 
(c) Intermediate-class golfer C: Less than 5 years' experience, 40 years 
old (male), head speed of 40 m/sec. 
2. Method of testing: 
Each golfer struck balls 20 times by using the golf clubs according to the 
present invention and the conventional golf club. The balls were hit at 
random in predetermined order on the basis of a randamized number table in 
consideration of golfers' familiarization to the golf clubs and the 
physical fatigue, which influence the resultant data. 
3. Method of determining the rate of occurrence of slice: 
A target was placed in a position directly opposite to and 50 m away from a 
ball to be driven, and a ball driven toward the target and went spinning 
off therefrom by not less than 30.degree. to the right of a right-handed 
golfer was judged to be a slice. The rate of occurrence of slice was 
calculated as a percentage. The number of hooked balls was out of the 
count. 
TABLE 1 
______________________________________ 
Angle of 
center of 
Face Lie gravity 
Item angle .theta..sub.1 
angle .theta..sub.2 
.theta..sub.3 
L 
______________________________________ 
Present 2.0.degree. 
6.0.degree. 
31.degree. 
14.0 mm 
Example 
Conven- -1.0.degree. 
57.degree. 25.degree. 
12.0 mm 
tional 
Example 
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TABLE 2 
______________________________________ 
Rate of Slice 
Present 
Conventional 
Example 
Example 
______________________________________ 
Beginner A 70% 83% 
Beginner B 48% 78% 
Intermediate 37% 45% 
class golfer C 
______________________________________ 
As is clear from Table 2, it can be said that the rate of occurrence of 
slice of the wood type golf club according to the present invention is 
certainly improved over that of the conventional wood type golf club 
without exception. Especially, the rate of occurrence of slice of the 
beginner B with less than 2 years' experience was improved by 30%, and 
even the rate of occurrence of slice of the beginner A having less than 1 
year's experience and a head speed of 37 m/sec by 13%. Accordingly, it is 
understood that the wood type golf club according to the present invention 
enables, especially, a beginner and a golfer having a low head speed to 
greatly reduce the frequency in the occurrence of slice. 
According to the present invention described above, in which the face angle 
.theta..sub.1 of the club head, lie angle .theta..sub.2 and angle of 
center of gravity .theta..sub.3 are set to 0.degree..ltoreq..theta..sub.1 
.ltoreq.5.degree. toward the closed face, 58.degree..ltoreq..theta..sub.2 
.ltoreq.62.degree. and 27.degree..ltoreq..theta..sub.3 .ltoreq.33.degree. 
respectively in relation with one another, can restrain the curving of a 
driven ball to the right of a right-handed golfer, i.e. the occurrence of 
slice. This wood type golf club is used very effectively, especially, by a 
beginner and a golfer having a low head speed.