Note: Descriptions are shown in the official language in which they were submitted.
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GOLF CLUB SET WITH IMPROVED
OFF-CENTER IMPACT PERFORMANCE
BACKGROUND OF THE INVENTION
This invention relates to golf clubs of the type have
in iron heads for use on tees and fairways, and more par-
titularly to an improvement in the performance of the clubs
of a set in response to an off-center impact with a golf
ball.
It is now well understood that although the golfer
controls the swing of a golf club head, at impact the club
head behaves as though it were a free mass having a portico-
far velocity. Most of the energy of this mass is imparted
to the ball in about half a millisecond, after which the
ball compressed against the club face springs clear of it as
i-t resumes its spherical shape.
Ideally, the center ox impact between the club head
and the ball is below the center of gravity so that the club
head will twist downward during impact. This twisting in-
creases backspin on the ball normally produced due to the
loft of the club head.
To better understand the backspin normally produced on
the ball, the club head should be visualized as a wedge
driven between the ground and the ball, rather than as a
mallet as used to strike a ball in croquet or polo. During
I the time the ball is in contact with the club head, the ball
will tend to slide up the face of the club and friction
imparts backspin which is opposite to the rotation the ball
Waldo have if it were rolling away prom the golfer on the
ground. Consequently, by the time the ball springs free of
the club face, significant backspin has been imparted to the
ball.
This backspin is desired ion order to stop the ball
from rolling forward on the ground once it alights, portico-
laxly when the ball alights on the green. By designing the
club head so that the center of impact will normally be
below the center of gravity, the twisting action referred to
above is produced. Such twisting action adds to the back-
spin normally produced. However, the twisting action some-
times results in a vibration of the clue head that is trays-
furred through the shaft to "sting" the golfers hands.
Worse yet, any vibration that is set up in the club head
also interferes with the normal flexing of the end of the
shaft during impact. That flexing is desired because as the
ball springs free of the club face, the flexed shaft
straightens out to impart extra force to the ball.
It would be desirable to uncouple the twisting
action of the club head from the shaft. Then any vibrations
of the club head will not affect the flexing of the shaft.
The club head would be allowed to twist more freely for
greater backspin control. This control of backspin may be
achieved for each stroke by raising or lowering the center
of impact on the club face as required.
SUMMARY OF THE INVENTION
-
The invention is in a set of correlated iron-
type golf clubs, the head of each club having a main body,
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a hostel for receiving a shaft, and a neck connecting said
hovel to said main body, said Cain body having a face for
striking a ball, a sole, a toe, and an upper edge inclined
upwardly from said neck. to said toe, an improvement come
prosed of a shape for said neck defined by a smooth convex
curve, as viewed from the face, of approximately constant
radius over a sector extending from said sole to said hovel,
and a sharper concave curve of shorter radius extending up
to said hovel over a smaller sector approximately centered
on the sector of said smooth curve of greater radius to
define a neck having at its mid-cross session a maximum
dimension which is smaller than the. diameter of said hovel
at the lower end of said Hazel wart connects to said
neck, whereby said neck uncouples the twisting action of
said club head from said shaft.
' The novel features that are considered character-
fistic of this invention are set forth with particularity
in the appended claims. The invention will best be under-
stood from the following description when read in connection
2Q with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
_. . . . . .. . .. _
FIG. 1 is a schematic diagram which illustrates
the twisting action of a conventional prior-art club head
impacting a ball.
FIG. 2 is a front view of the conventional
prior-art club head shown in-FIG. 1.
FIG. 3 is a front view of an iron club head
embodying the present invention.
I, 3
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FIG. 4 is a rear Vow of the club head shown
in FIG. 3.
FIG. 5 is an end view of the club head shown in
FIG. 3.
FIG. 6 is a top view of the club head shown in
FIG. 3 with the face in a vertical plane.
Figs pa and 7b are front and end views ox a
No. 2 club head of a correlated set embodying the present
invention.
pa
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Figs pa and 8b are front and end views of a No. 5
club head of the same correlated set embodying the present
invention.
Figs pa and 9b are front and end views of a club head
for a pitching wedge of the same correlated set embodying
the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to Figs 1 and 2, there is shown a
conventional club head 10 impacting a ball 12 with the eon-
ton of impact between the club head and ball at a point Boyle the center of gravity, COG, of the club head. As the
club head moves into the ball, the ball tends to slide up
the sloping face 15 of the club head, but due to friction
the ball will actually roll up, thus imparting backspin to
the ball. Impact with the ball also produces a clockwise
twisting motion of the club head about its center of gravity
as indicated, which in turn imparts a counterclockwise rota-
lion of the ball due to the gear effect between the club
face and the ball surface. This twist of the club head thus
increases the backspin otherwise being imparted to the
ball.
The amount of twist produced in the club head is a
function of how far the center of impact is below the center
of gravity. This is a factor over which the golfer has
control, and since controlled backspin is desired by the
golfer, it is desirable to have the club head twist free of
the club shaft 16.
As noted herein before, the lower end of the club shaft
I 2
will flex back during impact, as shown in FIG. 1, thus story
in energy that is released as the ball leaves the club head
and the flexed shaft springs forward. The ball will thus
leave the club head not only with additional backspin due to
S the twisting action of the club head, but also with add-
tonal velocity.
Polk of these effects are coupled if prowar lo
clubs (of the general configuration shown in FIG. 1) due to
a thick neck 18 used to connect the main body 20 of the club
head to a hovel 22, as illustrated more clearly in FIG. 2
which shows the club head 10 of FIG. 1 as viewed from the
front. Its upper edge 24 and sole 26 of the club head ox-
tend to the neck 18 which curves up sharply to meet the
hovel.
From the two views shown in Figs 1 and 2, it can be
seen that the neck is purposely made very rigid. It can
thus be appreciated that the main body I of the club head
(sometimes referred to hereinafter as the "club head pro-
per") is rigidly connected to the hovel 22 by a very rigid
neck 18. Consequently, any twisting of the club head proper
will pivot the hovel forward, thereby causing the shaft 16
to bend near the hovel.
.
In the case of impact with the ball below the center
of gravity, the bending will be in the same direction as the
flexing of the shaft, as illustrated in FIG. 1, but may
nevertheless cause vibrations that will travel through the
shaft to the golfer's hands. What can be worse is that
twisting of the club head and flexing ox the shaft may be
impeded by the rigid neck 18 so that optimum backspin and
velocity of the ball may not be achieved. In the case of
impact with the ball above the center of gravity to produce
forward or top spin of the ball, the club head will twist in
the direction opposite that shown in FIG. 1, i.e., counter-
clockwise, to cause the hovel to pivot against the normal flexing of the shaft, in which case severe vibrations may be
created in the club head and shaft. The present invention
uncouples the club head proper from the hovel so that twist-
in of the club head proper will not affect the normal flex-
in of the shaft, and optimum spin (back or forward) maybe imparted to the ball.
Referring now to Figs 3, 4 and 5, which illustrate a
front, rear and end view of a head 30 for a No. 8 iron, a
main body 32 is connected to a hovel 34 by a narrowed neck
36. An upper edge 38 extends through at least the scored
portion of the club face and then slopes downward to merge
with an upper curve 40 of the neck. A sole 42 extends
through the length of the club head and merges with a lower
curve 44 of the neck. The upper and lower curves are select
ted to define a neck that is narrowest in a midsection thereof, i.e., a cross section of the neck in this midsec-
lion 46 will have a maximum dimension that is smaller than
the diameter of the hovel 34. The neck 36 will thus unyoke-
lion as a torsion bar, twisting about the center of this
midsection 46 when the main body 32 of the head 30 is twist
ted in one direction and the hovel is not twisted, or is
twisted in the opposite direction.
This torsion occurs only under the tremendous force
produced by the club head impacting a ball with very high
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velocity (about lymph). Because of this midsection 46
having a smeller cross section than the rest of the narrowed
neck, the main body 32 of the club head will twist about an
axis 48 passing through the center 47 of this midsection and
the center of gravity, COG, of the club head 30. Thus, to
achieve a torsion-bar effect that uncouples the twist of the
main body 32 of the club head 30 from the hovel 34, the
narrow neck 36 is made narrower at its midsection 40 such
that its largest dimension across is less than the diameter
of the hovel, and its smallest dimension (seen in FIG. 6) is
significantly less.
Figs pa, pa and pa illustrate No. 2, No. 5 and pitch-
in wedge club heads of a correlated golf club set, each of
which has been provided with a narrow neck as described with
reference to Figs 3 through 6 for a No. 8 iron. Figs 7b,
8b and 9b illustrate end views of the club heads of Figs
pa, pa and pa, respectively.
Although particular embodiments of the invention have
been described and illustrated herein, it is recognized that
modifications and variations may readily occur to those
skilled in the art. Consequently, it is intended that the
claims be interpreted to cover such modifications and vane-
lions.
