U.S. patent application number 10/959802 was filed with the patent office on 2005-02-24 for hybrid golf club.
Invention is credited to Burnett, Michael Scott, Gilbert, Peter J., Meyer, Jeffrey W..
Application Number | 20050043117 10/959802 |
Document ID | / |
Family ID | 46205375 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050043117 |
Kind Code |
A1 |
Gilbert, Peter J. ; et
al. |
February 24, 2005 |
Hybrid golf club
Abstract
A hybrid golf club having a hollow club head construction
including a lightweight composite core inserted into a club head
cavity and juxtaposed against a front face by compressed gas to
provide support to the front face therein. The core material is
less dense and having greater flexibility than the front face. The
front face has a variable stiffness so as to create a variable
Coefficient of Restitution (COR) across the face, therein
normalizing the hitting area over a greater portion of the face.
The composite core supports the front face to provide a COR from
about 0.8 in the middle of the face to about 0.9 in the outer
section. The body of the club head has at least one opening wherein
the composite core is visible and provides the shell for that
portion of the club head. The composite core comprises a plurality
of unidirectional layers with horizontal oriented layers
alternating with vertical oriented layers to provide extra
strength.
Inventors: |
Gilbert, Peter J.;
(Carlsbad, CA) ; Burnett, Michael Scott;
(Carlsbad, CA) ; Meyer, Jeffrey W.; (Fallbrook,
CA) |
Correspondence
Address: |
ACUSHNET COMPANY
333 BRIDGE STREET
P. O. BOX 965
FAIRHAVEN
MA
02719
US
|
Family ID: |
46205375 |
Appl. No.: |
10/959802 |
Filed: |
October 6, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10959802 |
Oct 6, 2004 |
|
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|
10606317 |
Jun 25, 2003 |
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Current U.S.
Class: |
473/345 |
Current CPC
Class: |
A63B 53/0433 20200801;
A63B 60/02 20151001; A63B 2053/0491 20130101; A63B 53/0475
20130101; A63B 2209/00 20130101; A63B 53/0466 20130101; A63B
53/0408 20200801; A63B 53/047 20130101; A63B 53/0412 20200801; A63B
53/002 20200801; A63B 2209/02 20130101 |
Class at
Publication: |
473/345 |
International
Class: |
A63B 053/04 |
Claims
What is claimed is:
1. A golf club head comprising: a body made of a first material
having a front face of variable stiffness, and a rear cavity
extending rearward from the front face; a composite core comprised
of a second material less dense and more flexible than the first
inserted into the rear cavity; the composite core comprising a
plurality of unidirectional carbon fiber layers, with horizontal
direction layers alternating with vertical direction layers; the
composite core inflated and expanded by a pressurized gas wherein
at least a portion of the composite core biasly juxtaposes against
the front face to form a hollow body having an internal volume
between 35 cc to 50 cc.
2. The club head of claim 1, wherein the composite core is made
from a lightweight material such as carbon graphite.
3. The club head of claim 2, wherein the composite core material
has a density equal or less than 4.5 gm/cc.
4. The club head of claim 1, wherein the plurality of layers is
six.
5. The club head of claim 1, wherein the stiffness of the front
face is greatest at the face center, and becomes progressively more
flexible away from the face center.
6. The club head of claim 1, wherein the Coefficient of Restitution
varies across the front face to normalize ball speed and provide
for an enlarged sweet zone.
7. The club head of claim 5, wherein the maximum Coefficient of
Restitution, ranges between about 0.8 to about 0.9.
8. The club head of claim 1, wherein the pressurized gas is
air.
9. The club head of claim 1, wherein the rear cavity comprises an
opening that is sealed by a visible portion of the composite
core.
10. The club head of claim 1, wherein the elasticity of the
material of the composite core may cooperate with the front face to
create a varying COR across the front face for normalizing ball
speed and creating an enlarged sweet zone.
11. The club head of claim 1, wherein the body is cast from 431
stainless steel.
12. The club head of claim 1, wherein the body comprises a sole
having a port defined therein for housing a plug, the plug having a
density heavier than the body.
13. The club head of claim 11, wherein the plug is made form a
tungsten material having a density greater than 14 g/cc.sup.3.
14. The club head of claim 1, wherein the front face includes a
loft of about 22.degree. and a ball backspin of less than 5000 rpm
when the ball exhibits a speed of about 126 mph at a launch angle
of about 14.degree..
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation-in-part of
co-pending U.S. patent application Ser. No. 10/606,317, filed on
Jun. 25, 2003,
FIELD OF THE INVENTION
[0002] This invention relates to a hybrid golf club having a hollow
golf club head with a composite core.
BACKGROUND OF THE INVENTION
[0003] The desire for perimeter weighting in a golf club iron is
well known in the art. This desire stems from the fact that as the
mass of the club is distributed towards the perimeter, the
trajectory of the hit ball becomes more accurate, despite
off-center hits away from the sweet spot of the golf club face or
hitting surface. Consequently, many modern golf club irons have a
rear cavity that extends towards the rear side of the face surface
of the iron. The weight saved, by creating a rear cavity in the
club, is re-distributed to the perimeter of the golf club head, and
the greater the volume of the cavity, the greater the amount of
mass of metal that can be redistributed to the perimeter of the
golf club head.
[0004] Conventionally, golf club heads were made from a single
material, usually stainless steel for some metal woods and iron
type clubs, and recently a large shift in the use of titanium for
metal woods. Carbon fiber composite materials have been introduced
in an effort to decrease the weight of the golf club head while
subsequently increasing the club head's volume. Composite materials
have been used widely to reinforce thin club faces, while providing
`feel" and in some instances vibration dampening.
[0005] Typically, in an iron club head, composite inserts are used
to support the rear surface of the front face. They are generally
sheets of composite attached with an adhesive. The lightweight
composite allows for the face to be thin and therefore a larger
face and bigger sweet spot.
[0006] It is desirable to provide a golf club that optimizes the
moment of inertia (MOI) and also normalizes the ball speed over a
large area of the face. Thus the ball is launched at similar speeds
over a large region to create a larger sweet zone.
SUMMARY OF THE INVENTION
[0007] The present invention is directed to a golf club having a
metal body with a hollow composite core structure. The body is made
of a first material having a front face of variable stiffness and a
rear cavity. The composite core is of a lower density than the body
and includes a portion juxtaposed with the front face for
support.
[0008] In one embodiment of the invention, a composite core and
metallic body are combined to form a hollow golf club head. The
composite is used to structurally support a thin front face, and
for increased Coefficient of Restitution (COR). Preferably, the
front face is of a higher density and lower Young's Modulus than
the composite core.
[0009] In an embodiment of the invention the front face has a first
stiffness at the center of gravity (near the center of the face)
and becomes progressively more flexible away from the center of
gravity. Preferably, the club is designed such that the face
provides substantially uniform ball speed from hits at various
locations, i.e., an enlarged sweet zone. The COR across the front
face varies from about 0.8 to about 0.9 across the front face. The
variation in flexibility across the face may be a result of the
front face structure alone, or it may result from a combination of
the front face and composite core structures or the front face and
composite core materials. The internal volume of the golf club iron
head is about 35 cc to 50 cc.
[0010] An embodiment of the invention is comprised of a metal body
member that may be cast, forged, stamped or made by metal injection
molding. The body member is placed in a mold and a composite core
is biasly inflated and expanded against the metal body and mold by
a bladder method. Preferably, the composite core is located such
that the composite material is juxtaposed against portions of the
metal body and mold. The mold is used as a boundary for specific
regions of the club head where the metal body has an opening(s)
such that the exterior of the club is partially metal and partially
composite. Embodiments of the invention may be provided in both
hollow irons as well as metal woods.
[0011] The composite core is made up of a plurality of carbon fiber
layers, preferably six, each layer is unidirectional, and
horizontal oriented layers alternate with vertical oriented layers
to provide strength.
[0012] The club has a port in the sole for the introduction and
removal of a bladder material. This port houses a plug, preferably
a heavy material such as tungsten which has a density greater than
14 g/cc.sup.3. The extra weight in the sole is allowed by the
removal of weight in the body, especially in the front face which
may be very thin because of the lightweight composite core backing.
The weight placed in the sole provides for increased peak
trajectory.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a rear view of the hybrid club of the present
invention showing the exposed bladder molded composite core.
[0014] FIG. 2 is a sole view showing the plug position.
[0015] FIG. 3 is schematic toe view showing the center of gravity
for a Titleist.RTM. Model 503-H 22.degree. of the present invention
in relationship to a conventional 3 iron, such as a Titleist.RTM.
Model 804.
[0016] FIG. 4 is a cross-sectional view along line A-A of the
invention of FIG. 1 showing the bladder molded composite core
[0017] FIG. 5 is a schematic showing the six layers of carbon fiber
that forms the composite core.
[0018] FIG. 6 is a bar chart indicating potential carry
distance.
[0019] FIG. 7 is a bar chart indicating peak trajectory height and
roll distance.
DETAILED DESCRIPTION OF THE INVENTION
[0020] An embodiment of an iron golf club head 10 of the present
invention is shown on FIGS. 1 to 5. The body 12 of the golf club
head 10 has a metal portion having a front face 16 for striking
golf balls, a top section 15, a sole 17 having an open port 19, a
hosel 21, and a rear opening 25. A sole plug 26 is inserted within
the port 19, as discussed later. The body 12 has a cavity 22 that
is defined rearward of the face section 14. A lightweight composite
core 20 is biasly placed within the cavity 22, juxtaposed against a
rear surface 18 of the body 12, to internally reinforce the body
12, and also support the front face 16. The composite core 20
preferably has a composite structure made-up of a plurality of
unidirectional carbon fiber layers, preferably six layers, with the
horizontal direction fibers alternated with the vertical direction
fibers for optimum strength. The metal body 12 may be cast, forged,
stamped or made by a metal injection molding method, preferably the
head is cast from 431 stainless steel. Reinforcing the body 12 with
the lightweight composite core 20 allows for the body 12 to be
thinned down in select regions. The thinned down regions permit the
mass distribution optimization (Center of Gravity and Moment of
Inertia) of the club head 10, and also stiffening the front face 16
that may be relatively flexible due to the thin structure, and
therein allows for weight distribution and also dampening of
vibrations which helps to create solid feel.
[0021] The front face 16 can be made relatively thin because of the
reinforcement of the composite core 20. The thickness (t1) of the
front face 16 is preferably in a range between about 0.04 inch to
0.12 inch, and more preferably, between about 0.06 inch to 0.1
inch, while the thickness (t2) of the composite core 20 is
preferably between about 0.02 inch to about 0.1 inch. The composite
reinforced front face 16 can be designed to provide face
flexibility characteristics that yield maximum Coefficient of
Restitution (COR) values from about 0.8 to about 0.9. The COR of
the club head 10 may vary across the front face 16 to normalize
ball speed and provide an enlarged sweet zone for added
forgiveness. Therein the COR of the club 10 of the present
invention may be about 0.8 at the face center and greater than 0.8
away from the face center. Generally, the stiffness of the front
face 16 is greatest at the face center, and becomes progressively
more flexible away from the face center. The coefficient of
restitution is obtained under test conditions, such as those
specified by the USGA. The standard USGA conditions for measuring
the coefficient of restitution is set forth in the USGA Procedure
for Measuring the Velocity Ratio of a Club Head for Conformance to
Rule 4-1e, Appendix II available from the U.S.G.A.
[0022] The club head 10 forms a hollow style club 10 with thin
walls in select regions, especially the upper 14a and lower 14b
regions of the face side 16. The composite core 20 may be made of
plastic, carbon graphite or any lightweight material with a density
less than 4.5 gm/cc, and may be inserted into the hollow golf club
10 in a variety of methods. While the method of inserting the
composite core 20 may vary, the bladder method is preferred. In
this method, a composite core 20 composed of a carbon fiber
pre-preg material that is cut into face, body and rear lay-up
pieces are pressurized by a bladder (not shown) that is inserted
into the cavity 22 through a port 19. The bladder is preferably
made from latex, silicone, or similar materials. Preferably, the
composite core 20 is located such that the composite material is
juxtaposed against portions of the metal body 12 and the mold. The
assembly comprises, the metal golf club body 12, composite core 20,
and bladder. When positioned in a mold, which is not shown, the
composite core 20 is used as a boundary for specific regions of the
club head 10 where the metal body 12 has an opening, such as the
rear opening 25. Thus, the exterior of the resultant club head 10
is partially metal and partially composite. A source of pressurized
gas, usually air, (source not shown) is introduced through the port
19 to inflate and expand the bladder, and thereby cause plies of
the composite core 20 to biasly expand against the inner walls of
the golf club 10 and against the internal walls of the mold. The
internal walls of the tool are used as a boundary for a region of
composite or plastic that is visible to the outside of the golf
club 10. Heat may be provided at a predetermined temperature for a
selected period of time, i.e., a time sufficient to allow proper
curing of the composite material, which for an embodiment of the
invention is maintaining the club head 10 in a mold for about 30
minutes, at a pressure of about 50 psi and a temperature of about
275.degree. F. After depressurizing, the bladder may be removed
through the port 19, and the golf club head 10 may be removed from
the mold. The exterior of the resultant club head 10 is partially
metal body 12 and partially composite core material 20 with an
internal volume between about 35 cc to 50 cc. Upon removal from the
mold, the head 10 has molding residue removed and the perimeter of
the club head 10 is sanded smooth and the polished for a final
scratch finish. The rear piece of the composite core 20 has a clear
coat applied and artwork is performed with a laser alignment
fixture prior to a lacquer applied to the face and a sole number
painted thereon to finish the head.
[0023] The introduction of the plug 26 in the port 19 causes the
center of gravity of the club head to be lowered. Plugs 26 of
varying weight can adjust the swing weight of the club to match a
golfer's specifications. An embodiment of the invention used a plug
26 made from tungsten with a density of about 14 g/cm.sup.3.
[0024] FIG. 3 illustrates the relationship of the center of gravity
of a Titleist.RTM. Model 503-H, 22.degree. loft hybrid iron of the
present invention, and a Titleist.RTM. Model 804, 3 iron, which
would be the iron closest in specification to the hybrid club. The
center of gravity of the hybrid Model 503-H is lower and further
rearward than the 3 iron. This will mean greater distance and
greater peak trajectory which translates into a better "drop and
stop".TM. performance. The Model 503-H with about a 22.degree. loft
will yield a ball backspin of less than 5000 rpm at a ball speed of
about 126 mph at a launch angle of about 14.degree..
[0025] Performance test data utilizing the swing characteristics of
the "Average Tour Player" is available for the Model 503-H hybrid
irons against conventional iron clubs. FIG. 6 is a chart depicting
the carry distance of the average tour player for various irons and
fairway woods. The Model 503-H hybrid with a 22.degree. loft would
fall between the 3 and 2 irons with a carry distance of 221 yards
versus the 217 yards expected with the 3 iron and 224 yards with
the 2 iron. The Model 503-H hybrid with a 19.degree. loft will
deliver 229 yards versus 224 yards for a 2 iron and 234 yards with
a 19.degree. fairway wood. FIG. 7 correlates the data from FIG. 6
and what it means as to peak trajectory height and roll
distance.
[0026] The hybrid design offers a hollow construction, wide and low
bounce sole for a more forgiving club than a traditional long iron,
thin front face supported by the composite core, a lowered and
further back center of gravity improves launch angle and spin, all
of which makes for an easier to hit golf club than the
traditionally designed long irons. These hybrid clubs are designed
as an easier hitting alternative to the 2, 3 and 4 irons and/or 3,
4, 5 and 7 fairway woods depending on individual preferences.
[0027] The construction of the club head 10 can comprise a
variation in the thickness of the front face 16, in which the front
face 16 is preferably partitioned into oval regions, each having a
progressively lower stiffness. Thus, moving away from the face
center, the front face 16 decreases in stiffness and thus increases
in flexibility, therein increasing the COR in that area. This
design normalizes ball speed over a large range, thus improving the
golf club's "forgiveness" or enlarged sweet spot. The front face 16
may be made such that it's flexibility in the face center
(proximate the location of the CG) is generally stiffer than the
area around the face center. The increase in COR in combination
with the energy loss, that occurs from missing a direct central hit
on the front face 16, balances out to thereby give the same ball
speed as a shot hit directly in line with the face center. While it
is known that variable face flexibility can be achieved by making
adjustments in the thickness of the front face 16, an example of
the invention accomplishes the varying of flexibility by
incorporating a varying composite stiffness (via geometry or
material variations).
[0028] It is believed that those skilled in the pertinent art will
recognize the improved inventive concepts of this invention. And
they will readily understand that while the present invention has
been described in association with a preferred embodiment thereof,
and other embodiments illustrated in the accompanying drawings,
numerous changes, modifications and substitutions of equivalents
may be made therein without departing from the spirit and scope of
this invention.
* * * * *