U.S. patent application number 13/327210 was filed with the patent office on 2012-04-05 for golf club-heads having a particular relationship of face area to face mass.
This patent application is currently assigned to Taylor Made Golf Company, Inc.. Invention is credited to Todd P. Beach, Bing-Ling Chao, Peter L. Larsen.
Application Number | 20120083361 13/327210 |
Document ID | / |
Family ID | 39528044 |
Filed Date | 2012-04-05 |
United States Patent
Application |
20120083361 |
Kind Code |
A1 |
Beach; Todd P. ; et
al. |
April 5, 2012 |
GOLF CLUB-HEADS HAVING A PARTICULAR RELATIONSHIP OF FACE AREA TO
FACE MASS
Abstract
Golf clubs and club-heads for same are disclosed. An exemplary
club-head has a hollow body and a face plate. The body defines a
front opening and a face support, wherein the face plate is affixed
to the face support and covers the front opening. The "face
portion" of the club-head has a face area (A.sub.f, in mm.sup.2)
and a face mass (M.sub.f, in grams), wherein A.sub.f.gtoreq.5400
mm.sup.2, and in a plot of M.sub.f as a function of A.sub.f,
M.sub.f is below M.sub.f=0.0072(A.sub.f)+18. At least a portion of
the face plate can be made of composite. E.g., the face plate can
include a composite plate made of carbon fiber and cured epoxy
resin. The strike face of the face plate can include a composite
plate and a cap bonded to the composite plate on the strike face.
The cap can be made of a metallic material, such as (but not
limited to) titanium alloy or stainless steel.
Inventors: |
Beach; Todd P.; (San Diego,
CA) ; Chao; Bing-Ling; (San Diego, CA) ;
Larsen; Peter L.; (Carlsbad, CA) |
Assignee: |
Taylor Made Golf Company,
Inc.
|
Family ID: |
39528044 |
Appl. No.: |
13/327210 |
Filed: |
December 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11642310 |
Dec 19, 2006 |
8096897 |
|
|
13327210 |
|
|
|
|
Current U.S.
Class: |
473/342 ;
473/345 |
Current CPC
Class: |
A63B 2209/02 20130101;
A63B 53/0425 20200801; A63B 2209/023 20130101; A63B 53/0408
20200801; A63B 2209/00 20130101; A63B 53/0458 20200801; A63B
53/0466 20130101; A63B 60/00 20151001; A63B 53/0416 20200801 |
Class at
Publication: |
473/342 ;
473/345 |
International
Class: |
A63B 53/04 20060101
A63B053/04; A63B 53/00 20060101 A63B053/00 |
Claims
1. A club-head for a golf club, comprising: a hollow body defining
a front opening having a face support; a face plate affixed to the
face support and covering the front opening; and a hosel; wherein a
face portion comprises the face plate, the front opening face
support, and a portion of the hollow body of the golf club head
located from a tangent plane of the face plate to approximately 12
mm rearward from the tangent plane of the face plate but not
including the hosel; and wherein the face portion of the club-head
has a face area (A.sub.f, in mm.sup.2) and a face portion mass
(M.sub.f, in grams), A.sub.f.gtoreq.5400 mm.sup.2 and a club-head
COR.ltoreq.0.830, and the face mass M.sub.f satisfies the
inequality M.sub.f<0.0072(A.sub.f)+18.
2. The club-head of claim 1, wherein the body comprises at least
one wall made of metal.
3. The club-head of claim 2, wherein the metal comprises titanium
alloy.
4. The club-head of claim 1, wherein at least a portion of the face
plate comprises a composite material.
5. The club-head of claim 4, wherein the face plate comprises a
composite plate.
6. The club-head of claim 5, wherein the composite plate comprises
carbon fiber and cured epoxy resin.
7. The club-head of claim 4, wherein: the face plate has a strike
face; and the face plate comprises a composite plate and a cap
bonded to the composite plate on the strike face.
8. The club-head of claim 7, wherein the cap comprises a metallic
material.
9. The club-head of claim 1, wherein the face plate has a
substantially uniform thickness.
10. The club-head of claim 1, wherein the face plate has a variable
thickness.
11. The club-head of claim 10, wherein peripheral regions of the
face plate are thinner than a central region of the face plate.
12. The club-head of claim 1, wherein: the face plate has a strike
face; the face plate comprises a composite plate and a metal cap
bonded to the composite plate on the strike face; the composite
plate has a substantially uniform thickness; and the metal cap has
a substantially uniform thickness.
13. The club-head of claim 1, wherein: the face plate has a strike
face; the face plate comprises a composite plate and a metal cap
bonded to the composite plate on the strike face; the composite
plate has a variable thickness; and the metal cap has a
substantially uniform thickness.
14. The club-head of claim 1, wherein: the face plate has a strike
face; the face plate comprises a composite plate and a metal cap
bonded to the composite plate on the strike face; and the body
comprises body walls comprising a titanium alloy.
15. The club-head of claim 1, wherein A.sub.f is within a range of
5400 to 10,000 mm.sup.2.
16. The club-head of claim 15, wherein A.sub.f is within a range of
7000 to 10,000 mm.sup.2.
17. The club-head of claim 15, wherein A.sub.f is within a range of
8500 to 10,000 mm.sup.2.
18. A golf club, comprising: a club-head, comprising a hollow body
and a face plate, the body defining a front opening having a face
support, and the face plate being affixed to the face support and
covering the front opening; a hosel; and a shaft affixed to the
hosel; wherein a face portion of the club-head comprises the face
plate, the front opening face support, and a portion of the hollow
body of the club-head located from a tangent plane of the face
plate to approximately 12 mm rearward from the tangent plane of the
face plate but not including the hosel; and wherein the face
portion of the club-head has a face area (A.sub.f; in mm.sup.2) and
a face portion mass (M.sub.f, in grams), A.sub.f.gtoreq.5400
mm.sup.2 and a club-head COR.ltoreq.0.830, and the face mass
satisfies the inequality M.sub.f.ltoreq.0.0072(A.sub.f)+18.
19. The golf club of claim 18, configured as a driver.
20. The golf club of claim 18, wherein at least a portion of the
face plate comprises a composite material.
21. The golf club of claim 20, wherein the face plate comprises a
composite plate.
22. The golf club of claim 21, wherein the composite plate
comprises carbon fiber and cured epoxy resin.
23. The golf club of claim 20, wherein: the face plate has a strike
face; and the face plate comprises a composite plate and a cap
bonded to the composite plate on the strike face.
24. The golf club of claim 23, wherein the cap comprises a metallic
material.
25. The golf club of claim 24, wherein the body comprises a
titanium alloy.
26. The golf club of claim 18, wherein the face plate has a
substantially uniform thickness.
27. The golf club of claim 18, wherein the face plate has a
variable thickness.
28. The golf club of claim 18, wherein A.sub.f is within a range of
5400 to 10,000 mm.sup.2.
29. The golf club of claim 28, wherein A.sub.f is within a range of
7000 to 10,000 mm.sup.2.
30. The golf club of claim 28, wherein A.sub.f is within a range of
8500 to 10,000 mm.sup.2.
Description
FIELD
[0001] This is a continuation of U.S. patent application Ser. No.
11/642,310, filed Dec. 19, 2006, and is hereby incorporated by
reference.
BACKGROUND
[0002] With the ever-increasing popularity and competitiveness of
golf, substantial effort and resources are currently being expended
to improve golf clubs so that increasingly more golfers can have
more enjoyment and more success at playing golf. Much of this
improvement activity has been in the realms of sophisticated
materials and club-head engineering. For example, modem "wood-type"
golf clubs (notably, "drivers" and "utility clubs"), with their
sophisticated shafts and non-wooden club-heads, bear little
resemblance to the "wood" drivers, low-loft long-irons, and higher
numbered fairway woods used years ago. These modem wood-type clubs
are generally called "metal-woods."
[0003] An exemplary metal-wood golf club such as a fairway wood or
driver typically includes a hollow shaft having a lower end to
which a hollow club-head is attached. Most of these club-heads are
made, at least in part, of a light-weight but strong metal such as
titanium alloy. The club-head comprises a body to which a strike
plate (also called a face plate) is attached or integrally formed.
The body includes a hosel that extends generally upward and is
connected to the shaft of the club. The body also includes a heel
region situated close to the hosel, a toe region situated opposite
the heel region, a sole (lower) region, and a crown (upper) region.
The body bears most of the impact load imparted to the strike plate
when the club-head strikes a golf ball. The strike plate defines a
front surface or strike face that actually contacts the golf
ball.
[0004] In contrast to wood-type clubs used years ago, the
club-heads of many modem metal-woods are hollow, which has been
made possible by the use of light-weight, strong metals and other
materials for fabricating the club-head. Use of titanium and other
light-weight metal alloys has permitted the walls of the club-head
to be made very thin, which has permitted the club-heads to be made
substantially larger than their predecessors. These larger
club-heads tend to provide a larger "sweet spot" on the strike
plate and to have higher club-head inertia, thereby making the
club-heads more "forgiving" than smaller club-heads. This
"forgiveness" means that a golfer using the club who strikes the
ball from a face location other than the sweet spot still produces
a ball trajectory that is substantially similar to the shot that he
otherwise would have made if he had struck the ball on the sweet
spot. Characteristics such as size of the sweet spot are determined
by many variables including the shape profile, size, and thickness
of the strike plate as well as the location of the center of
gravity (CG) and the moment of inertia (MOI) of the club-head.
[0005] There are practical limits to the maximum size of
club-heads, based on factors such as the particular material of the
club-head, the mass of the club-head, and the strength of the
club-head. Generally, as club-head sizes increase, body walls and
face plates are correspondingly thinner. The distribution of mass
around the club-head typically is quantified by parameters such as
rotational moment of inertia (MOI) and CG. Club-heads typically
have multiple MOIs, each associated with a respective Cartesian
reference axis (x, y, z) of the club-head. A rotational MOI is a
measure of the club-head's resistance to angular acceleration
(twisting or rotation) about the respective reference axis. The
MOIs are related to, inter alia, the distribution of mass in the
club-head with respect to the respective reference axes. Each of
the MOIs desirably is maximized as much as practicable to provide
the club-head with more forgiveness.
[0006] To achieve the high MOIs, the mass of the club-head
typically is distributed, as much as possible, strategically around
the periphery of the club-head and rearward of the face plate. As a
result, the club-head's CG generally is located rearwardly from the
face plate at a prescribed location, which helps the club produce a
desired launch angle upon impact with a golf ball.
[0007] Another factor in modern club-head design is the face plate.
Impact of the face plate with the golf ball causes some rearward
deflection of the face plate. This deflection and the subsequent
recoil of the face plate are expressed as the club-head's
coefficient of restitution (COR). A thinner face plate generally
deflects more at impact than a thicker face plate of the same
material, thus providing the thinner face plate with more recoil
than a thicker face plate. Consequently, a club-head having a
thinner face plate potentially can impart more energy and thus a
higher initial velocity (rebound velocity) to a struck golf ball
than a club with a thicker, more rigid face plate. This rebound
phenomenon is called the "trampoline effect" and is an important
determinant of the flight distance of the struck ball. Since
face-plate deflection is usually greater in the sweet spot, a ball
struck by the sweet spot generally will have a greater rebound
velocity than a ball struck off-center, and thus generally will
travel farther. Because of the importance of the trampoline effect,
the COR of clubs is limited under USGA rules.
[0008] To achieve these ends, it typically is desirable to
incorporate thin walls, including the face plate, into the designed
configuration of the club-head. Thin walls also allow additional
leeway in distributing club-head mass strategically to achieve a
desired mass distribution and a desired high COR.
[0009] The volume of club-heads of metal-woods is limited by USGA
rules. Nevertheless, certain of these club-heads have become rather
large, the largest having a volume of about 460 cm.sup.3. These
large club-heads have a correspondingly large strike face that
presents a tall face height to the ball. Consequently, with many
golfers using these clubs, there is an increased probability that
the ball will be struck by the strike plate at a location other
than the sweet spot. With a large strike face, these off-center
shots still provide good ball-launch velocity. However, currently
available large-area face plates add significant mass to the front
of the club-head, which reduces the amount of mass available for
placement elsewhere in the club-head, and undesirably shift the CG
forwardly.
[0010] Regarding the total mass of the club-head as the club-head's
mass budget, it is axiomatic that at least some of the mass be
dedicated to achieving the required strength and structural support
of the club-head. This is termed "structural" mass. Any mass
remaining in the budget is called "discretionary" or "performance"
mass, which can be distributed within the club-head to maximize
performance. Much of the current research and development activity
concerning golf clubs is directed to various ways of distributing
the discretionary mass. For example, some club-heads include one or
more weights placed relative to the heel-toe (x) axis and in-line
with the percussion axis of the club-head.
[0011] As club-head engineering converges on certain basic
arrangements of discretionary mass in a club-head, particularly in
metal-woods, obtaining a maximal amount of any remaining
discretionary mass is becoming increasingly important, especially
with larger club-heads. Conventional ways of removing mass from the
face plate are not always successful; if too much mass is removed
from the face plate, the structural mass of the strike plate may be
excessively compromised, which can result in the strike plate being
too fragile and/or its COR being too high.
[0012] Another conventional approach involves using alternative
materials for fabricating the club-head. Whereas the bodies and
face plates of most metal-woods currently on the market are made of
titanium alloy, several "hybrid" club-heads are available that are
made, at least in part, of graphite-composite or another composite
material. In one group of these club-heads the body is made of
composite, but titanium alloy or steel is used as the primary
face-plate material.
[0013] Other hybrid club-heads are made entirely of composite
material (notably graphite composite). But, for several reasons,
these club-heads tend to be limited to smaller face areas. First,
with a conventional face plate made of composite, it has heretofore
been difficult to provide the face plate with sufficient structural
strength while still conforming to USGA and R&A rules for the
"spring-like effect" (COR.ltoreq.0.830, CT.ltoreq.257 .mu.sec).
("CT" is the "characteristic time" standard.) Second, whereas
smaller club-heads made of composite can be mass-efficient,
potentially even more so than similarly sized all-metal club-heads,
scaling up the composite technology to produce desired larger face
areas results in less mass-efficiency. One cause of this decreased
mass efficiency is the required large thickness of the "sole lip"
and "crown lip" at which the face plate transitions to the body.
Joining a composite face plate to a composite body by current
technology requires not only careful overlap of face plies with
body plies in the transition zones, but also substantially thicker
transition zones, which tend to negate the potential mass savings
of replacing titanium alloy (density=4.5 g/cm.sup.3) with composite
(density=1.5 g/cm.sup.3 for graphite composite). Thus, this
technique is simply not mass-efficient (and may actually pose a
mass-penalty) for club-head configurations having large face areas.
There is also a general consensus that all-composite club-heads
produce a disagreeable impact sound during play, mainly due to the
overall stiffness of the composite structure and the damped nature
of composite material compared to metal.
[0014] In view of the above, a need exists for improved metal-wood
golf clubs and club-heads that have low-mass face plates,
especially large-area face plates, that have sufficient mechanical
strength for their intended use, and that conform to USGA and
R&A restrictions on the "Spring-Like Effect."
SUMMARY
[0015] The need articulated above is met by various aspects of the
instant invention, of which a first aspect pertains to club-heads
for golf clubs. An embodiment of such a club-head comprises a
hollow body and a face plate. The body defines a front opening
having a face support, and the face plate is affixed to the face
support and covers the front opening. The "face portion" (as
defined herein) of the club-head has a face area (A.sub.f) and a
face mass (M.sub.f, in grams), wherein A.sub.f.gtoreq.5400
mm.sup.2. In a plot of M.sub.f as a function of A.sub.f, M.sub.f is
below M.sub.f=0.0072(A.sub.f)+18.
[0016] In certain embodiments at least a portion of the face plate
comprises a composite material. For example, the face plate can
comprise a composite plate. The composite plate can comprise carbon
fiber and cured epoxy resin. In other embodiments the face plate
has a strike face, wherein the face plate comprises a composite
plate and a cap bonded to the composite plate on the strike face.
The cap can comprise a metallic material, such as (but not limited
to) titanium alloy or stainless steel.
[0017] In certain embodiments the face plate has a substantially
uniform thickness. In other embodiments the face plate has a
variable thickness. For example, the peripheral regions of the face
plate can be thinner than the central region of the face plate.
[0018] In other embodiments the face plate comprises a composite
plate and a metal cap bonded to the composite plate on the strike
face. The composite plate can have a substantially uniform
thickness, with the metal cap having a substantially uniform
thickness. Alternatively, the composite plate can have a variable
thickness, with the metal cap having a substantially uniform
thickness.
[0019] The body typically comprises body walls collectively having
an external contour for the particular club-head. The body walls
have a transition zone in which the body contour transitions to the
face plate. Desirably, the transition zone has an inside radius in
a range of 0.1 to 3.0 mm. This range is suitable for bodies
comprising any of various light-weight materials, such as titanium
alloy.
[0020] The face area A.sub.f desirably is within the range of 5400
to 10,000 mm.sup.2. More desirably, A.sub.f is within the range of
7000 to 10,000 mm.sup.2. Even more desirably, A.sub.f is within the
range of 8500 to 10,000 mm.sup.2.
[0021] According to another aspect, golf clubs are provided. An
embodiment of such a golf club comprises a club-head, comprising a
hollow body and a face plate. The body defines a front opening
having a face support, and the face plate is affixed to the face
support and covers the front opening. A shaft is affixed to the
club-head. With respect to the face portion of the club-head,
A.sub.f.gtoreq.5400 mm.sup.2, and in a plot of M.sub.f (in grams)
as a function of A.sub.f, M.sub.f is below
M.sub.f=0.0072(A.sub.f)+18. The golf club can be configured to
include a hosel to which the shaft is affixed. By way of example,
the golf club is configured as a driver or other metal-wood.
[0022] The face plate of the golf club can have any of the
configurations summarized above with respect to a club-head. For
example, the face plate can comprise a composite plate made of
carbon fiber and cured epoxy resin. A cap can be bonded to the
composite plate on the strike face. The cap can comprise a metallic
material such as, but not limited to, titanium alloy. Also, the
body can be made, at least in part, of titanium alloy and/or can
have a transition zone as summarized above. The face plate can have
a substantially uniform or a variable thickness.
[0023] The foregoing and additional features and advantages of the
invention will be more readily apparent from the following detailed
description, which proceeds with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a perspective view of a "metal-wood" club-head,
showing certain general features pertinent to the instant
disclosure.
[0025] FIGS. 2(A)-2(C) are respective orthogonal views depicting a
metal-wood club-head having a strike face and depicting a manner in
which the strike face transitions into the contour of the body of
the club-head.
[0026] FIG. 3 is a front elevational view of a metal-wood
club-head, depicting the manner of defining a first cut plane in
the method for obtaining a face portion of the club-head for
obtaining a standard measurement, as disclosed herein, of face area
and face mass.
[0027] FIG. 4 is a front elevational view of the club-head of FIG.
3, depicting a face plate on which a face center has been defined
as part of the method for obtaining a face portion.
[0028] FIG. 5 is a top view of the club-head of FIG. 3, depicting
the manner of defining a second cut plane in the method for
obtaining a face portion.
[0029] FIG. 6(A) is a front elevational view of the club-head of
FIG. 3, depicting the first cut plane, used in the method for
obtaining a face portion.
[0030] FIG. 6(B) is a front elevational view of the face portion
produced according to the method.
[0031] FIG. 7 is a schematic view of a reference surface (having a
precisely known area) and a face portion positioned for obtaining a
determination of the face area.
[0032] FIG. 8 is a plot of face mass versus face area, showing the
sloped line M.sub.f=0.0072(A.sub.f)+18, the vertical line
A.sub.f=5400, and a shaded area beneath the sloped line and to the
right of the vertical line.
[0033] FIG. 9 is a crown-to-sole sectional view showing certain
variables associated with the face support of the club-head.
[0034] FIG. 10 is a schematic diagram showing an exemplary manner
in which plies can be stacked in making a composite face plate.
[0035] FIG. 11 is a partial sectional view showing a face plate
comprising a composite plate and a metal cap, and certain
relationships established when the face plate is bonded to the body
of the club-head.
[0036] FIG. 12(A) is a front elevational view of the club-head of
Examples 1 and 2.
[0037] FIG. 12(B) is a partial sectional view of the upper lip
region of the club-head of FIG. 12(A).
[0038] FIG. 13 is a side elevational section of an exemplary face
plate comprising a composite portion and a metal cap, and having a
non-uniform thickness, as evaluated in Example 2.
[0039] FIG. 14(A) is a front elevational view of the club-head of
Example 3.
[0040] FIG. 14(B) is a partial sectional view of the upper lip
region of the club-head of FIG. 14(A).
DETAILED DESCRIPTION
[0041] This disclosure is set forth in the context of
representative embodiments that are not intended to be limiting in
any way.
[0042] In the following description, certain terms may be used such
as "up," "down,", "upper," "lower," "horizontal," "vertical,"
"left," "right," and the like. These terms are used, where
applicable, to provide some clarity of description when dealing
with relative relationships. But, these terms are not intended to
imply absolute relationships, positions, and/or orientations. For
example, with respect to an object, an "upper" surface can become a
"lower" surface simply by turning the object over. Nevertheless, it
is still the same object.
[0043] The main features of an exemplary metal-wood club-head 10
are depicted in FIG. 1. The club-head 10 comprises a face plate 12
and a hollow body 14. The face plate 12 typically is convex, and
has an external ("striking") surface (face) 13. The body 14 has
walls and defines a front opening 16. A face support 18 is disposed
about the front opening 16. The body 14 also has a heel 20, a toe
22, a sole 24, a top or crown 26, and a hosel 28. Around the front
opening 16 is a "transition zone" 15 that extends along the
respective forward edges of the heel 20, the toe 22, the sole 24,
and the crown 26. The transition zone 15 effectively is a
transition from the walls of the body 14 to the face plate 12. The
opening 16 receives the face plate 12, which rests upon and is
bonded to the face support 18 and transition zone 15, thereby
enclosing the front opening 16. The transition zone 15 includes a
sole-lip region 18d, a crown-lip region 18a, a heel-lip region 18c,
and a toe-lip region 18b. The hosel 28 defines an opening 30 that
receives a distal end of a shaft (not shown).
[0044] The subject club-heads satisfy a particular relationship of
face mass as a function of face area. More specifically, for face
areas (A.sub.f) of 5400 mm.sup.2 and greater, the range of face
mass resides below the linear plot M.sub.f=0.0072(A.sub.f)+18,
wherein M.sub.f is the face mass (g), and A.sub.f is the face area
(mm.sup.2). A key variable in this relationship is the face area
A.sub.f, which is defined and determined as follows:
[0045] As discussed above, all club-heads have a face (strike
surface) 13 that is intended to hit the golf ball. In the
transition zone 15 of a metal-wood 10 the face 13 transitions to
the external contour of the body 14, as shown in FIGS. 2(A)-2(C).
The shapes of the face 13 and the transition zone 15 can vary
substantially from club-head to club-head and from manufacturer to
manufacturer. In view of these differences, it is important to have
a standard definition of and method for measuring face area
A.sub.f. Part of the task of defining face area A.sub.f is dealing
with the hose 28. The hosel 28 is generally not intended as a
ball-impact location and thus should not be included in the
determination of face area A.sub.f or face mass M.sub.f. Since the
hosel 28 serves only to connect the club-head to the shaft of the
golf club, and since a few club-heads currently available have
so-called "internal hosel" configurations, the manner of
determining face area A.sub.f (as well as face mass M.sub.f) should
exclude any contributions by the hosel, regardless of the club-head
configuration.
[0046] The desired manner of determining face area A.sub.f is as
follows, described with reference to a conventional club-head for a
metal-wood as shown in FIG. 3. The club-head includes a body 14, a
sole 24, a face 13 and a hosel 28. The hosel 28 extends along a
hosel axis A.sub.h. A "hosel-normal" plane 50 is defined that is
normal to the hosel axis A.sub.h. The hosel axis A.sub.h also is
the axis of rotation of a cylinder 52 having a radius of 29.6 mm.
The hosel-normal plane 50 is located on the hosel axis A.sub.h such
that the cylinder 52 intersects the hosel-normal plane 50 and
touches the surface of the body 14 at the point 54. A first cut
plane 56 is defined as being parallel to the hosel-normal plane 50
but displaced 2.4 mm toward the sole 24. The first cut plane 56 can
be denoted by the line 58 that can be scribed on the face 13 and
used later as a cut-line for removing the hosel 28 from the
club-head.
[0047] The face center 60 of the face 13 is located using a method
as described in the USGA pendulum test ("Procedure for Measuring
the Flexibility of a Golf Clubhead," Rev. 2.0, Mar. 25, 2005). A
typical face center 60 is shown in FIG. 4. Turning now to FIG. 5, a
"tangent plane" 62 is defined as being tangent to the face 13 at
the face center 60 and normal to the "loft plane" (not shown) of
the club-head. A second cut plane 64 is defined as being parallel
to the tangent plane 62 but located 12.+-.1 mm rearward of the
tangent plane.
[0048] The club-head desirably is cut first along the second cut
plane 64 (FIG. 5) to remove the front portion 66 from the rear
portion 68. Then, on the front portion 66 (FIG. 6(A)), a second cut
is made along the first cut plane 56, using the line 58 as a guide
(see FIG. 6), to remove the hosel 28. The resulting face portion 70
(FIG. 6(B)) represents a standard face-area for the club-head and
is used for determining the actual face area A.sub.f of the
club-head.
[0049] To determine the face area, and turning now to FIG. 7, the
face portion 70 is placed adjacent a reference portion 72 (having a
precisely known reference area) on a planar background 74. The face
portion 70 and reference portion 72 are imaged (preferably
digitally) from a position normal to the planar background 74.
Photo-editing software is used to detect the edges of, and the
number of pixels inside, the reference portion 72 (in one example
259,150 "black" pixels made up the reference area of 5,010
mm.sup.2). Similarly, the software is used to detect the edges of,
and number of pixels inside, the face portion 70 (in the example
298,890 black pixels made up the area of the face portion 70). The
actual face area is calculated as follows:
A f = P f A r P r ##EQU00001##
wherein A.sub.f is the face area, P.sub.f is the pixel count in the
face portion 70, A.sub.r is the area of the reference portion 72,
and P.sub.r is the pixel count in the reference portion 72. In the
example, if A.sub.r=5,110 mm.sup.2, P.sub.f=298,890 pixels, and
P.sub.r=259,150 pixels, then A.sub.f=5,894 mm.sup.2.
[0050] It will be understood that the pixel-counting technique
described above is an example of a technique capable of measuring
area accurately and precisely. Other are-measurement techniques can
be employed in alternative methods
[0051] With face areas being determined for any of various
metal-wood club-heads, reference is now made to FIG. 8, which is a
plot of face mass (M.sub.f), in gram units, as a function of face
area (A.sub.f) in units of mm.sup.2. Face mass M.sub.f is obtained
simply by weighing the face portion 70. The depicted plot also
includes the line M.sub.f=0.0072(A.sub.f)+18 and a vertical line
A.sub.f=5400 mm.sup.2. Also shown is a shaded region below the line
M.sub.f=0.0072(A.sub.f)+18 and to the right of the line
A.sub.f=5400. The various points located outside of the shaded
region represent data obtained with conventional metal-wood
club-heads. The points located inside the shaded area represent
data exhibited by three respective examples that are discussed
later below. The terms M.sub.f and A.sub.f as used in the claims
have respective meanings as discussed above.
[0052] In various embodiments, the face area A.sub.f is generally
greater than 5400 mm.sup.2, desirably in the range of 5400 to
10,000 mm.sup.2, more desirably in the range of 7000 to 10,000
mm.sup.2, and most desirably in the range of 8500 to 10,000
mm.sup.2.
[0053] Turning now to FIG. 9, the face support 18 includes a
peripheral member 80 extending rearward from forward walls 82 and a
rear member 84 extending inward with reference to the front opening
16. The face support includes portions proximate to the top, the
toe, the heel, and the sole (see items 18a, 18b, 18c, 18d in FIG.
1). In certain embodiments, the face support is continuous about
the front opening, as shown in FIG. 1. In other embodiments, one or
more portions of the face support 18 are configured as multiple
tabs spaced apart from each other about the front opening 16.
[0054] Referring further to FIG. 1, the face support 18 is
recessed, allowing the face 13 (strike surface) of the face plate
12 to be flush with the forward wall 82 of the body. In the
respective portions of the face support 18 that are proximal the
crown 26 and sole 24, the peripheral member 80 is generally
perpendicular to a face plane P.sub.f defined by the face plate 12,
and the rear member 84 is generally parallel to the face plane. A
loft plane P.sub.L of the club head is normal to the face plane
P.sub.f and forms an acute angle .theta. with a horizontal
plane.
[0055] The face support 18 is structured to provide ample surface
area for receiving the face plate, thereby aiding in club
durability. By way of example, the rear member 84 of the face
support 18 has a thickness T.sub.R in the range of 0.5-2.5 mm and a
length L.sub.R in the range of 2-25 mm. These and other parameters
of the face support 18 can vary among various embodiments, based on
factors such as materials used to fabricate the face plate 12, the
volume of the club-head, and the dimensions of the face plate.
Desirably, the thickness T.sub.R is in the range of 0.6-1.5 mm, and
the length L.sub.R is in the range of 2-7 mm. The peripheral member
80 of the face support 18 has a thickness T.sub.P in the range of
0.5-2.5 mm, and a length L.sub.P in the range of 3-30 mm.
Desirably, the thickness T.sub.P is in the range of 0.8-1.2 mm, and
more desirably is about 1 mm. The peripheral member 80 desirably
has a length L.sub.P in the range of 4-6 mm. While the peripheral
member 80 most desirably has a substantially constant thickness,
the rear member 84 desirably tapers inwardly toward the center of
the front opening 16. With such a configuration, at the inner end
of the rear member, the thickness T.sub.E is in the range of
0.6-0.9 mm.
[0056] The junction of the peripheral member 80 and rear member 84
of the face support 18 desirably has a maximum thickness T.sub.J in
the range of 1.5-2 mm. The peripheral member 80 can be spaced from
an inner surface of the crown by a distance S.sub.1, measured in
the vertical direction, of at least 1 mm. In such methods, the
peripheral member 80 is spaced from the inner surface of the sole
by a vertical distance S.sub.2 of at least 1 mm. Desirably, the
peripheral member 80 is spaced S.sub.1, S.sub.2 vertically at least
1.5 mm from the crown and sole.
[0057] Preferred dimensions for the body 14 of the club-head are in
the range of 0.7-1 mm thickness T.sub.C for the crown 26 and in the
range of 0.8-1.2 mm thickness T.sub.S for the sole 24. The wall
thickness T transitioning to the forward wall 82 and the front
opening 16 at the crown 26, sole 24, toe 22, and heel 20 is
desirably in the range of 0.6 to 1.5 mm to provide a smoother
transition to the thickness T.sub.P of the peripheral member 80 of
the face support 18. The transition has a radius desirably in the
range of 0.1 to 3 mm.
[0058] For mass reduction, high strength, and durability, at least
a portion of the face plate 12 is a composite portion including
multiple plies or layers of a fibrous material embedded in a cured
resin (e.g., epoxy). An exemplary thickness range of the composite
portion is 4.5 mm or less. The composite portion is configured to
have a relatively consistent distribution of reinforcement fibers
across a cross-section of its thickness to facilitate efficient
distribution of impact forces and overall durability. The composite
portion includes multiple "prepreg" plies. A prepreg ply has a
respective fiber reinforcement impregnated with partially cured
resin matrix. The fiber reinforcement and resin are selected to
contribute to the club's durability and overall performance. Tests
have demonstrated that composite portions formed of prepreg plies
having a relatively low fiber areal weight (FAW) provide superior
attributes in several areas, such as impact resistance, durability,
and overall club performance. (FAW is the weight of the fiber
portion of a given quantity of prepreg, in units of g/m.sup.2.) FAW
values below 200 g/m.sup.2, and more desirably below 100 g/m.sup.2,
are effective. In this regard, a particularly suitable fibrous
material for the prepreg plies is carbon fiber. More than one
fibrous material can be used.
[0059] Lower FAW prepreg plies are desired for handling the large
force resulting from golf-ball impact. This force is primarily
transverse to the orientation of the fibers. Prepreg plies having
lower FAW are thinner than those having higher FAW. Consequently,
more plies can be assembled using lower FAW plies for a chosen face
thickness. This provides the ability to: (1) reduce the progressive
change in fiber ply, or (2) allow more frequent repetition of fiber
angles through the thickness, to resist the primary failure mode
(interlaminar shear) for faces made entirely or partially from
composite material. Lower FAW materials accomplish these aims more
effectively, especially if plies of material are included that have
fibers that do not span the entire face (i.e., smaller elliptical
plies located near the face center). However, since the cost of
lower FAW materials is higher than of higher FAW prepreg of the
same fiber and resin content, a balance desirably is achieved
between durability, performance, and cost.
[0060] The fibers of each ply have a respective orientation. More
specifically, each prepreg ply has a prescribed orientation, and
the plies are stacked in a prescribed order and orientation. For
convenience of reference, the orientation of the plies is measured
from a horizontal axis of the club-head's face plane to a line that
is aligned with the fibers in the ply. Referring to FIG. 10, for
example, fiber orientation is indicated by dashed lines. A first
ply 120 is oriented at 90 degrees, followed by multiple unit-groups
122, 124, 126 of plies each having four plies oriented at 90, +45,
0, and -45 degrees, respectively. The resulting stack of
unit-groups of plies is sandwiched between an "outer" ply 128 and
an "inner" ply 130. In this embodiment, the inner and outer plies
128, 130 are formed of prepreg reinforced by glass fibers, such as
1080 glass fibers (scrim weave). The other plies are formed of
unidirectional prepreg carbon fiber.
[0061] An example carbon fiber is "34-700" carbon fiber, available
from Grafil, Sacramento, Calif.), having a tensile modulus of 234
Gpa (34 Msi) and a tensile strength of 4500 Mpa (650 ksi). Another
Grafil carbon fiber that can be used is "Pyrofil TR50S", which has
a tensile modulus of 240 Gpa (35 Msi) and a tensile strength of
4900 Mpa (710 ksi). A suitable epoxy resin is type "301" (from
Newport Adhesives and Composites, Irvine, Calif.). An exemplary
final resin content (R/C) is 40%.
[0062] In the general procedure described above, stacking the
prepreg plies in predetermined orientations may be done by first
stacking individual plies in the unit-groups 122, 124, 126, and
then stacking a desired number of unit-groups (and any additional
desired plies) to form the final thickness of the composite. The
inner ply 128 and outer ply 130 desirably are made of a different
fiber material than used in the plies of the unit-groups. The
number of unit-groups can be varied as desired. One embodiment
comprised sixteen unit-groups of 70 g/m.sup.2 FAW material with
fiber properties as stated above.
[0063] The composite face plate can be provided with its final
desired shape and dimensions by die cutting. Any desired bulge and
roll of the face plate may be formed during the last of two or more
"debulking" or compaction steps (performed before curing, to remove
and/or reduce air trapped between plies). To form the bulge or
roll, the "last" debulking step can be performed against a die
panel having the final desired bulge and roll. If desired, yet
another (and subsequent) debulking step can be performed using the
die panel to achieve the final face-plate thickness. The weight and
thickness of the face plate desirably are measured before the
curing step.
[0064] The potential mass "savings" obtained from fabricating at
least a portion of the face plate of composite is about 10-30 g, or
more, relative to a 2.7-mm thick face plate formed from a titanium
alloy such as Ti-6Al-4V, for example (depending upon face
area).
[0065] Attaching a composite face plate to the club-head body may
be achieved using an appropriate adhesive (typically an epoxy
adhesive). To prevent peel and delamination failure at the junction
of an all-composite face plate with the body of the club-head, the
composite face plate should be recessed from or be substantially
flush with the plane of the forward surface of the metal body at
the junction. Preferably, the composite face plate is sufficiently
recessed so that the ends of the fibers in the plies are not
exposed. In other embodiments as shown, for example, in FIG. 11,
the face plate 12 comprises a metal "cap" 90 formed or placed over
the composite plate 92 to form the strike surface 13. A
particularly desirable metal for the cap 90 is titanium alloy, such
as the particular alloy used for fabricating the body (e.g.,
Ti-6Al-4V). Desirably, the cap 90 includes a peripheral rim 94 that
covers the peripheral edge 96 of the composite plate 92. The rim 94
can be continuous or discontinuous, the latter comprising multiple
segments (not shown). For a cap 90 made of titanium alloy, the
thickness of the titanium desirably is less than about 1 mm, and
more desirably 0.07 to 0.3 mm. In one example, in which the
thickness of the composite plate 92 was about 3.65 mm, a titanium
cap 90 was used having a thickness of about 0.3 mm. The candidate
titanium alloys for making the cap 90 are not limited to Ti-6Al-4V,
and the base metal of the alloy is not limited to Ti. Other
materials can be used as desired for making the cap, such as
polymers, stainless steel, and other metals.
[0066] The metal cap 90 desirably is bonded to the composite face
plate using a suitable adhesive 98, such as an epoxy or
polyurethane adhesive. The adhesive 98 is applied so at to fill the
gap completely between the cap 90 and the composite plate 92 (this
gap usually in the range of about 0.05-0.2 mm, and desirably is
approximately 0.1 mm). The face plate 12 desirably is bonded to the
body using a suitable adhesive 100, such as an epoxy adhesive.
[0067] Surface roughness can be imparted to the composite plate 92
(notably to any surface thereof that will be adhesively bonded to
the body of the club-head and/or to the metal cap 92). In a first
approach, a layer of textured film is placed on the composite plate
92 before curing the film (e.g., "top" and/or "bottom" layers
discussed above). An example of such a textured film is ordinary
nylon fabric. Conditions under which the adhesives 98 100 are cured
normally do not degrade nylon fabric, so the nylon fabric is easily
used for imprinting the surface topography of the nylon fabric to
the surface of the composite plate. By imparting such surface
roughness, adhesion of urethane and epoxy, such as 3M.RTM. DP 460,
to the surface of the composite plate so treated was greatly
improved and superior to adhesion to a metallic surface, such as
cast titanium alloy.
[0068] In a second approach, texture can be incorporated into the
surface of a mould used for fanning the composite plate 92, thereby
allowing the textured area to be controlled precisely and
automatically. For example, in an embodiment having a composite
plate joined to a cast body, texture can be located on surfaces
where shear and peel are dominant modes of failure.
[0069] A third approach involves sandblasting the scrim-weave plies
128, 130 to achieve a desired surface roughness.
Example 1
[0070] In this example, a driver club-head was fabricated having a
hollow titanium body (Ti-6Al-4V) and a composite face plate having
a metal cap. The body is shown in FIGS. 12(A)-12(B), wherein FIG.
12(A) is a face normal (elevational) view and FIG. 12(B) is a
section through a portion of the lip. Width and height dimensions
(in mm) of the opening for the face plate are shown in FIG. 12(A),
and representative lip dimensions (in mm) are shown in FIG. 12(B).
The radius of the lip is generally in the range of 0.1 to 3.0 mm,
more desirably in the range of 0.1 to 1.0 mm.
[0071] The composite portion of the face had a mass of 26.6 g, and
comprised 70 g/m.sup.2 FAW carbon fiber material (34-700 carbon
fiber; 34 Msi tensile modulus, 700 ksi ultimate tensile strength),
and 40% R/C. Composite layup (front to back) was constant
thickness: glass scrim+[Q]15+[90]+glass scrim, where
Q=[90/+45/0/-45] from carbon fiber noted above, yielding a total of
61 plies.
[0072] The metal cap was made of 0.076 mm thick stainless steel
(2.1 g), and bonded to the composite portion of the face plate
using 0.5 g epoxy. The resulting total mass of the face plate was
29.2 g. The face plate was bonded to the body using 1.0 g epoxy.
The total mass of the face (prepared as described above) was 57 g,
and the face area was 5865 mm.sup.2. The club-head exhibited a
COR=0.820 and a CT=229 .mu.sec, which was within regulations. The
datum 150 for this club head is shown in FIG. 10.
[0073] It is noted that the same mass-to-COR/CT performance was
obtained for higher FAW as well (i.e., 150 g/mm.sup.2) and a lower
resin content (about 34%).
Example 2
[0074] In this example, a driver club-head was fabricated having a
hollow titanium body (Ti-6Al-4V) and a composite face plate having
a metal cap. The body was the same as used in Example 1.
[0075] The composite portion of the face plate had a mass of 20.5
g, and comprised 150 g/m.sup.2 FAW carbon-fiber material (34-700
carbon fiber having 34 Msi tensile modulus and 700 ksi ultimate
tensile strength), and 40% final R/C. Composite layup (front to
back) was variable thickness: glass scrim+[Q]+[q+Q]4+[0/90]+glass
scrim, where Q=[90/+45/0/-45], full face size, from carbon fiber
noted above. Referring to FIG. 13, the composite portion 110 of the
face plate 12 was 22 plies thick (carbon fiber) at the edges 112,
and 38 plies thick (carbon fiber) at face center 113. Where
q=[90/+45/0/-45], shapes smaller than the face are positioned near
"face center." The resulting "interlaminar plies" create the
variable thickness of the face 12 plate shown in FIG. 13.
[0076] The metal cap 114 of the face plate 12 was made of 0.3 mm
thick Ti alloy (5.6 g), and bonded to the composite portion 110
using 0.7 g epoxy. The resulting total mass of the face plate 12
was 26.8 g. To join the face plate to the body, 1.0 g epoxy was
used. The total mass of the face (prepared as described above) was
54.8 g, and the face area was 5800 mm.sup.2. The club-head
exhibited a COR=0.824 and a CT=233 .mu.sec, which are within
regulations. The datum 152 for this club head is shown in FIG.
10.
Example 3
[0077] In this example, a driver club-head was fabricated having a
hollow titanium body (Ti-6Al-4V) and a composite face plate having
a metal cap. The body is shown in FIGS. 14(A)-14(B), wherein FIG.
14(A) is a face normal (elevational) view and FIG. 14(B) is a
section through a portion of the lip. Width and height dimensions
of the opening for the face plate are shown in FIG. 14(A), and
representative lip dimensions are shown in FIG. 14(B).
[0078] The composite portion of the face plate had a mass of 22.6
g, and comprised 70 g/m.sup.2 FAW carbon-fiber material (34-700
carbon fiber having 34 Msi tensile modulus and 700 ksi ultimate
tensile strength), and 40% final R/C. Composite layup (front to
back) was variable thickness: glass
scrim+[Q]2+[q+Q]8+[Q]+[90]+glass scrim, where Q=[90/+45/0/-45],
full face size, from carbon fiber noted above. The composite
portion was 45 plies thick (carbon fiber) at face edges, and 77
plies thick (carbon fiber) at face center. Where q=[90/+45/0/-45],
shapes smaller than the face are positioned near "face center." The
resulting "interlaminar plies" create the variable thickness of the
face plate shown in FIG. 13.
[0079] The metal cap portion of the face plate was made of 0.3 mm
thick Ti alloy (6.0 g), and bonded to the composite portion using
0.6 g epoxy. The resulting total mass of the face plate was 29.2 g.
To join the face plate to the body, 1.0 g epoxy was used. The total
mass of the face (prepared as described above) was 55.6 g, and the
face area was 6060 mm.sup.2. The club-head exhibited a COR=0.815
and a CT=224 .mu.sec, which are within regulations. The datum 154
for this club head is shown in FIG. 10.
[0080] Whereas the invention has been described in connection with
representative embodiments, it will be understood that the
invention is not limited to those embodiments. On the contrary, the
invention is intended to encompass all modifications, alternatives,
and equivalents as may be included in the spirit and scope of the
invention, as defined by the appended claims.
* * * * *