U.S. patent application number 11/199063 was filed with the patent office on 2007-01-11 for multi-component golf club head.
Invention is credited to Stephen S. Murphy.
Application Number | 20070010350 11/199063 |
Document ID | / |
Family ID | 46325039 |
Filed Date | 2007-01-11 |
United States Patent
Application |
20070010350 |
Kind Code |
A1 |
Murphy; Stephen S. |
January 11, 2007 |
Multi-component golf club head
Abstract
A metal wood golf club head adapted for attachment to a shaft,
having a stiff lower front face and a compliant upper front face.
An insert serves as an impact face. The lower front face has a
substantially greater thickness providing a stiffer face area. A
cavity behind the lower front face removes undesired weight from
the front face and allowing for weight to be redistributed to more
desirable locations.
Inventors: |
Murphy; Stephen S.;
(Carlsbad, CA) |
Correspondence
Address: |
ACUSHNET COMPANY
333 BRIDGE STREET
P. O. BOX 965
FAIRHAVEN
MA
02719
US
|
Family ID: |
46325039 |
Appl. No.: |
11/199063 |
Filed: |
August 8, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10662682 |
Sep 15, 2003 |
|
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11199063 |
Aug 8, 2005 |
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Current U.S.
Class: |
473/349 |
Current CPC
Class: |
A63B 53/0466 20130101;
A63B 2209/023 20130101; A63B 53/0433 20200801; A63B 60/00 20151001;
A63B 53/0408 20200801; A63B 2209/00 20130101; A63B 53/0416
20200801; A63B 53/0462 20200801; A63B 53/0437 20200801 |
Class at
Publication: |
473/349 |
International
Class: |
A63B 53/00 20060101
A63B053/00 |
Claims
1. A metal wood golf club head comprising: a variable front face
having a stiff lower area and a compliant upper area; the variable
front face including a cast body having a face perimeter defining
an opening and an impact insert attached within the opening; and a
cavity defined in the lower area of the cast body filled with a
lightweight reinforcing material, wherein a heavy mass is removed
from the stiff lower area and relocated to an area of the club head
causing the center of gravity of the club head to be shifted
rearward from the front face.
2. The club head of claim 1, wherein the impact insert is formed of
sheet metal.
3. The club head of claim 1, wherein the impact insert is
forged.
4. The club head of claim 1, wherein the impact insert is cast.
5. The club head of claim 1, wherein the impact insert is welded to
the face perimeter of the cast body.
6. The club head of claim 1, wherein the cavity defined in the
lower area is filled with a plastic material.
7. The club head of claim 1, wherein the cavity defined in the
lower area is filled with a ceramic material.
8. The club head of claim 1, wherein the cavity defined in the
lower area is filled with air.
9. The club head of claim 1, wherein a cover seals the cavity, the
cover being attached over the cavity by welding.
10. The club head of claim 1, wherein a cover seals the cavity, the
cover being attached over the cavity by an epoxy.
11. The golf club head according to claim 1, wherein the club head
has a maximum coefficient of restitution greater than 0.80.
12. The golf club head of claim 1, wherein the thickness of the
front face is greater at the lower area than at the upper area.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation-in-part of
co-pending U.S. patent application Ser. No. 10/662,682, filed on
Sep. 15, 2003, wherein the disclosure of the parent application is
incorporated herein in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a multi-material,
multi-component metal wood golf club head having an improved face
design.
BACKGROUND OF THE INVENTION
[0003] Golf clubs have achieved a remarkable transformation from
persimmon wood clubs to the present day metal woods with their
extremely large head sizes. This has been made possible by high
strength metallic materials, which allow the golf ball to be hit
farther and straighter because of increased club head inertia and
coefficient of restitution.
[0004] Particularly, development of titanium alloys, which are
light (specific gravity: 4.5 to 5.0) and strong, have allowed
significant increases in the head size and subsequent practical
shaft length of a golf club. Specifically, a large moment of
inertia, resulting in an increased area of high speed on the club
face can be achieved by use of a large club head. Thus there is a
constant demand for club heads of greater size. However, enlarging
the club head also increases its weight. Most of the metal wood
golf clubs manufactured today have a shell thickness so thin that
they border on practical manufacturing limits. Golf club
manufacturers are looking for solutions wherein lighter and
stronger materials may be employed to achieve results such as lower
ball spin and higher launch angles.
[0005] Among the more prominent considerations in club head design
are loft, lie, face angle, horizontal face bulge, vertical face
roll, center of gravity, inertia, material selection, and overall
head weight. While this basic set of criteria is generally the
focus of golf club engineering, several other design aspects must
also be addressed. The club design may be improved to yield longer
ball flight, and maximize ball velocity after impact while
remaining within the rules.
[0006] The United States Golf Association (USGA), the governing
body for the rules of golf in the United States, has specifications
for the performance of golf clubs and golf balls. Golf clubs are
limited to a Coefficient of Restitution (COR) of 0.83. One USGA
rule limits the golf ball's initial velocity after a prescribed
impact to 250 feet per second .+-.2% (or 255 feet per second
maximum initial velocity).
SUMMARY OF THE INVENTION
[0007] The present invention relates to a multi-material,
multi-component metal wood golf club head comprised of a front face
having a geometric face center, wherein the center of gravity is at
least 6 mm lower than the geometric face center, and the point of
maximum Coefficient of Restitution (COR) is not lower than 2 mm
below the geometric face center.
[0008] An embodiment of the invention, designated as club head,
comprises a first body portion, a second body portion, and a hosel
member. The first body portion comprises a cup-like face section, a
sole section, and a bore-thru hosel tube. The second body portion
comprises at least a crown section and a substantial portion of a
skirt section, and is of a lower density than the first body
portion. The density of the second body portion may be between
about 0.1 g/cc to 4.0 g/cc.
[0009] The material of construction for the first body portion may
be a stainless steel alloy, but preferably is a titanium alloy.
While magnesium is preferred for the second body portion,
composite, or other lightweight metal such as aluminum, or a
thermoplastic may be substituted for the magnesium, but with
different performance characteristics. The third body portion is a
hosel section formed from a lightweight metal or a thermoplastic,
including nylon, composite or aluminum materials.
[0010] The club head of the present invention has a coefficient of
restitution (COR) greater than 0.80, with a COR gradient created in
the front face. The thickness of the face is preferably
progressively greater in a direction from the crown section to the
sole section. This is a beneficial design consideration, since the
club head has a lowered center of gravity, the greater face
thickness at the sole section refocuses the COR towards the center
of the face.
[0011] The weight reduction, due to the use of lower density
materials in the second body portion and hosel member, allows for
that weight to be relocated in the club head. The present invention
provides for a weight member, having a generally horseshoe shape,
to be positioned on the inside surface of the sole section, at a
point near the sole/skirt junction. This further lowers the club
head center of gravity and moves it farther from the face, and
preferably at least 12 mm from the centerline of the shaft
axis.
[0012] Another embodiment of the invention utilizes only two body
portions, the light weight second portion incorporating both the
crown section and the hosel member.
[0013] One embodiment of the invention discloses a metal wood with
a face having an impact zone comprising a stiff lower area and a
compliant upper area, with a cavity defined in the lower area which
can be filled by either a lightweight material such as plastic,
ceramic, or even air. The cavity has a cover that is either welded
or held on by an epoxy. The body of the club is cast and he casting
includes the cavity. The impact face is a welded insert.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a front schematic of a golf club with the face
square and the club head soled in the address position for
depicting the face center and center of gravity based on test
data.
[0015] FIG. 2 is a top schematic of FIG. 1.
[0016] FIG. 3 is an expanded pictorial view of an embodiment of the
invention, having three body portions.
[0017] FIG. 4 is a top view of FIG. 3 thereof.
[0018] FIG. 5 is a cut out top view taken along line A-A of FIG.
8.
[0019] FIG. 6 is a partial cross-sectional view showing the
bore-thru hosel tube and weight member.
[0020] FIG. 7 is a toe view of FIG. 3 thereof.
[0021] FIG. 8 is a front view of FIG. 3 thereof.
[0022] FIG. 9 is an expanded pictorial view of another embodiment
of the invention. having two body portions.
[0023] FIG. 10 is a top view of FIG. 9 thereof.
[0024] FIG. 11 is a toe view of FIG. 9 thereof.
[0025] FIG. 12 is a front view of FIG. 9 thereof
[0026] FIG. 13a is a side view of the variable thickness front face
of the present invention.
[0027] FIG. 13b is a side view of the variable thickness front face
of an alternate embodiment.
[0028] FIG. 13c is a side view of a variable thickness front face
with a hollow cavity in the cast body.
[0029] FIG. 14 is a graph illustrating the relationship of launch
angles to the face center for the prior art Titleist.RTM. 983K
driver.
[0030] FIG. 15 is a graph illustrating the relationship of launch
angles to the front face for the present invention.
[0031] FIG. 16 is a graph depicting the relationship of backspin to
the front face for the prior art Titleist.RTM. 983 K.
[0032] FIG. 17 is a graph depicting the relationship of backspin to
the front face for the present invention.
[0033] FIG. 18 is a graph relating ball speed to front face for the
prior art 983K.
[0034] FIG. 19 is a graph relating ball speed to front face for the
present invention.
[0035] FIG. 20 is a graph showing ball distance at positions on the
front face of the prior art 983K.
[0036] FIG. 21 is a graph showing ball distance at positions on the
front face of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0037] The golf club head according to preferred embodiments of the
present invention, is a multi-material and multi-component hollow
club head.
[0038] As shown is FIGS. 3-8, a club head 30 is generally composed
of three components, which includes a first body portion 31, a
second body portion 32 and a hosel member 33. First body portion 31
is substantially comprised of: a cup-shaped front face section 37;
a sole section 36 that includes a horseshoe shaped high density
weight member 40 that is positioned on the inner surface of the
sole section 36 at a predetermined distance from the front face
section 37; and, a bore-thru-hosel tube 42. Second body portion 32
is of a lower density than the first body portion 31 and comprises
at least a crown section 34, and a substantial portion of a skirt
section 35. Hosel member 33 is also of a low density material
having one end 45 for connection to a shaft (not shown) and the
opposing end 46 for connection to the bore-thru-hosel tube 42.
[0039] The density range for second body portion 32 and hosel
member 33, is from about 0.1 g/cc to 4.0 g/cc. Both may be formed
from materials such as aluminum, graphite composite, a
thermoplastic, but the preferred material for the second body
portion 32 is magnesium, and the preferred material for the hosel
member 33 is nylon. The method of manufacturing the portions 32 and
33, may be casting, injection molded, machining, prepreg sheet
formed, and the like. Preferably, the second body portion 32 has a
thickness in the range of about 0.5 mm to about 1.5 mm, and more
preferably less than about 1.0 mm. An advantage of injection
molding is that it may provide the second body portion 32 with a
geometrically complex shape that includes the crown section 34 and
a substantial part of the skirt section 35.
[0040] The materials for forming first body portion 31 may be
stainless steel, pure titanium or a titanium alloy. The more
preferred material comprises titanium alloys, such as titanium 6-4
alloy, which comprises 6% aluminum and 4% vanadium, or SP-700
titanium alloy, which comprises 4.7% aluminum, 2.9% vanadium, 2.0%
molybdenum and 2.1% iron and is commercially available from NKK
(Japan) and RTI International Metals (Niles, Ohio). First body
portion 31 may be manufactured through casting with a face insert
that is made by forming, or forging with a stamped sole, or forming
a wrapped face with a stamped sole, or powdered metal forming, or
metal-injection-molding and the like.
[0041] By using magnesium for the second body portion 32, a certain
amount of weight may be reassigned to the weight member 40, which
is integral with the sole section 36. The horseshoe shaped weight
member 40 has a specified density is the range from about 4 g/cc to
20 g/cc, and may be selected from such materials as tungsten,
molybdenum or another like metal in a like density range. Weight
member 40 may be cast, injection molded, machined or formed by a
powdered metal process. Weight member 40 is positioned away from
the face section 37, a critical design concept for the lowering of
the center of gravity C. The methods for determining the
positioning of the center of gravity C and the calculation of the
geometric face center X are shown on schematic FIGS. 1 and 2.
Dimensions were measured with the club head face square and the
club soled in the address position.
[0042] Three embodiments of the club head 30 design of the present
invention were tested against a prior art club (Titleist.RTM. 983K
driver) which is very similar in appearance, size and shape of the
embodiments of the present invention. The three embodiments were
all generally identical to each other except for the materials of
construction of the second and third body portions 32, 33.
[0043] Test results for determining the position of the center of
gravity C as it relates to the geometric face center are presented
below in Table I, for three different embodiments of the present
invention. Test data is also presented for the prior art club head
Titleist.RTM. 983K, for comparison purposes. TABLE-US-00001 TABLE I
(Clubhead Mass Properties) Titleist .RTM. Embodiment Embodiment
Embodiment From 983K A B C (mm) (mm) (mm) (mm) CG-Xfc 4.37 -2.05
-0.4 -0.88 CG-Yfc 2.29 -7.88 -6.61 -8.19 CG-Zfc 31.89 31.08 30.30
31.12 CG-B 35.76 31.44 32.30 31.34 CG-C -15.47 -15.26 -14.92 -14.86
FC-X -27.79 -21.18 -23.27 -22.59 FC-Y 27.29 29.85 29.46 29.59 FC-Z
16.42 15.82 15.38 16.27 MOI IMPACTS (kg-mm.sup.2) (kg-mm.sup.2)
(kg-mm.sup.2) (kg-mm.sup.2) High-low - x 231.2 217.6 225.2 218.9
Heel-toe - y 358.6 370.3 414.5 355.7 Lofted - z 351.3 255.4 293.0
251.9 About shaft 653.9 563.5 582.3 557.9 (a) Embodiment A
comprises magnesium second body portion 32 and a nylon hosel member
33. (b) Embodiment B comprises a composite second body portion 32
and an aluminum hosel member 33. (c) Embodiment C comprises a
composite second body portion 32 and a nylon hosel member 33.
[0044] Embodiment A of the present invention provides for a shift
in the center of gravity C to a position at least 6 mm below the
geometric face center X. The actual test results show the center of
gravity C to be 7.88 mm below its geometric face center X, while
tests for the Titleist.RTM.983K (having a titanium crown and skirt)
provided data indicating that the 983K's center of gravity was 2.29
mm above its geometric face center. Comparable shifts in the center
of gravity C are seen in the test data for embodiments B and C. The
Titleist.RTM. 983K has a volume of 363 cubic centimeters, and a
titanium SP700 stamped hitting face with a thickness of about 0.122
inch. Unlike the present invention, the 983K does not have a
thickness gradient in the hitting face 48 (discussed below). And,
while the second body portion 32 of the present invention is formed
from magnesium, and the hosel member 33 is formed of nylon, these
portions of the 983K are formed from the heavier titanium alloys.
Other than these differences, the embodiments of the present
invention and the 983K are very comparable in size and dimension.
Test results are shown in FIGS. 14-21.
[0045] FIGS. 14 and 15, depict data indicating launch angles of the
prior art Titleist.RTM.983K and Embodiment A (with the magnesium
second body portion 32) respectively. The low center of gravity C,
of Embodiment A, creates a launch angle of about 1.5.degree. higher
than that achieved with the prior art 983K club head (13.degree.
versus 11.5.degree.).
[0046] FIG. 16 graphically details the spin rate performance of the
prior art 983K club head versus the magnesium crown of Embodiment
A, as shown in FIG. 17. At the geometric face center of each club
head (shown as 0.00 on the X-Y coordinates), the present invention
produces a backspin of almost 500 rpm lower than the prior art
983K.
[0047] A significant improvement in ball speed of the present
invention over the prior art 983K can be best described by FIGS. 18
and 19. The maximum ball speed of the prior art club head is
achieved at a position about 0.20 inches above the geometric face
center (FIG. 18) while the maximum ball speed of the magnesium
crown present invention is maintained at about the geometric center
or lower. This point of maximum ball speed is the point of maximum
coefficient of restitution, which is often referred to by golfers
as the "sweet spot".
[0048] The final results are culminated in FIGS. 20 and 21. With
data taken at the geometric center for both club heads, FIG. 21
shows the club head of the present invention achieving an increase
of almost 7.5 yards over that of the prior art.
[0049] These figures depict the initial ball speeds when the clubs
traveling at about 110 mph impact Titleist PRO V1 balls. The angle
of attack is about 2.degree., and the effective loft angle is about
12.degree.. The clubs are mounted on a robot, which is driven to
impact the balls at the desired club speed. Robots are commercially
available from the True Temper Corporation or the Wilson.RTM.
Sporting Goods Co. The locations of ball impacts are distributed
over a rectangular area of 0.50 inch in the vertical direction and
about 1.0 inch in the horizontal direction. The mechanical driver
has the ability to repeatedly hit the balls at any desirable
location on the hitting face. The ball speeds are measured by
launch monitors. Any suitable launch monitors can be used. Examples
of launch monitors include those described in commonly owned U.S.
Pat. Nos. 6,533,674, 6,500,073, 6,488,591, 6,285,445, 6,241,622,
5,803,823 and 5,471,383, among others.
[0050] Preferably, the front face section 37 of the present
invention has a gradient thickness in the hitting face 48 ranging
from the thinnest thickness about the crown section 34 to the
thickest at the sole section 36. FIG. 13a depicts the preferred
front face section 37, as including a machined face insert, and
wherein T.sub.1, of the upper portion near the crown section 34 can
be as thin as about 0.08 inch (2.03 mm), the thickness T.sub.2, at
the middle section is about 3 mm, and the lower portion nearer to
the sole section 36 has a thickness T.sub.3 of about 0.20 inch (5.0
mm). This thickening of the lower region of the hitting face 48
causes an upward shift of the point of maximum coefficient of
restitution (COR) to a position not lower than 2 mm below the
geometric face center X and preferably about equal to the face
center X. The club head 30 has a COR of at least 0.80 under test
conditions, such as those specified by the USGA.
[0051] An alternate embodiment for the front face section 37 is
shown in FIG. 7b, wherein the face insert is of a constant
thickness in the T.sub.2 area and varied T.sub.1 and T.sub.3 areas,
with the thinnest thickness at the crown area. Not shown is another
alternative front face section wherein the insert area thickness
T.sub.2 is varied and the thickness of sections depicted by T.sub.1
and T.sub.3 are constant.
[0052] The standard USGA conditions for measuring the coefficient
of restitution is set forth in the USGA Procedure for measuring the
Velocity Ration of a Club Head for Conformance to Rule 4-1e,
Appendix II. Revision I, Aug. 4, 1998 and Revision 0, Jul. 6, 1998,
available from the USGA. Such tests measure COR by measuring ball
resiliency. COR is the ratio of the velocity of separation to the
velocity of approach. In this model, therefore, COR was determined
using the following formula:
(v.sub.club-post-v.sub.ball-post)/(v.sub.ball-pre-v.sub.club-pre)
where, v.sub.club-post represents the velocity of the club after
impact; [0053] v.sub.ball-post represents the velocity of the ball
after impact; [0054] v.sub.club-pre represents the velocity of the
club before impact (a value of zero for USGA COR conditions); and
[0055] v.sub.ball-post represents the velocity of the ball before
impact.
[0056] The COR, in general, depends on the shape and material
properties of the colliding bodies. A perfectly elastic impact has
a COR of one (1.0), indicating that no energy is lost, while a
perfectly inelastic or perfectly plastic impact has a COR of zero
(0.0), indicating that the colliding bodies did not separate after
impact resulting in a maximum loss of energy. Consequently, high
COR values are indicative of greater ball velocity and
distance.
[0057] First and second body portions, 31, 32 and hosel member 33,
are sized and dimensioned to be attached together by any
conventional methods used to join dissimilar materials, such as
brazing and structural adhesives. A high quality plasma welding
technique, similar to the welding technique used in Titleist.RTM.
983 driver club, is preferred.
[0058] An alternate embodiment, depicted by FIGS. 9-12, and
referred to as club head 50, illustrates the advantage of injection
molding the second body portion, wherein a hosel section 51 and
bore-thru-hosel tube 52 are integrated with a crown section 53 to
form a crown portion 54. The advantage is that even more of the
"high section" of the club head is made from a low density material
(compared to the club head of embodiment 30 where bore-thru is made
of higher density material). This allows for further lowering of
the center of gravity C. The challenge is that the hosel is
typically less rigid when made of low density material.
Conventional golf clubs typically include a hosel welded on to the
body of the club, which requires more manufacturing time and
increases the complexity of manufacturing.
[0059] An embodiment of the invention is shown on FIG. 13c, wherein
a cast metal wood body 61 has a face perimeter 69 defining an
opening 62 that is filled by an insert 63 which is welded to the
face perimeter 69 to serve as an impact face. The insert 63 can be
forged, sheet metal formed or cast. The cast metal wood body 61
combines with the insert 63 to create a variable front face which
is thicker at a lower area 65 and gradually thinner towards an
upper area 68. There is a cavity defined in the lower area 65 of
the cast body 61 rearward of the front face. This cavity 66 may be
filled with a lightweight material 67 such as plastic, a ceramic,
or air. The cavity 66 is sealed by a cover 68 which may be welded
or sealed by an epoxy or similar bonding agent. The greater
thickness of the lower area 65 makes the face of the club much
stiffer in that area while the thinner upper area 68 is more
compliant. This type of design results in a ball launch which after
impact has a lower spin and higher launch angle, and therein a
longer ball flight while maintaining a Coefficient of Restitution
greater than 80. While the stiffer lower area 65 and compliant
upper area 68 create a desirable metal wood design, having a large
amount of mass towards the front of the club head is not desirable.
The creation of the cavity 66 allows a substantial amount of weight
to be removed from the front, possibly to be moved to a more
desirable location in the club head. It is well known in the design
of metal woods, that moving weight away from the front face and
placing it low in the club head, helps create a preferred club head
center of gravity. The present design allows for the club head to
be thicker and therefore stiffer in the lower area of the face, but
without the extra mass. The cavity 66 allows for weight to be
shifted to more desirable areas of the club head.
[0060] Alternatively, the club head of the present invention may
also be used with the smaller fairway woods, which can have volume
as low as about 150 cubic centimeters. Preferably, the mass of the
inventive club head is greater than 150 grams but less than 300
grams. It is anticipated that a fairway wood may be made from the
design concepts of the present invention. Such a wood may have a
first body portion made of a metal such as stainless steel, a
second body portion (substantially the crown and skirt) made from a
lower density metal such as titanium, and a hosel member having a
density no greater than the second body portion.
[0061] While various descriptions of the present invention are
described above, it should be understood that the various features
of each embodiment could be used alone or in any combination
thereof. Therefore, this invention is not to be limited to only the
specifically preferred embodiments depicted herein. Further, it
should be understood that variations and modifications within the
spirit and scope of the invention might occur to those skilled in
the art to which the invention pertains.
* * * * *