U.S. patent application number 10/316453 was filed with the patent office on 2004-06-17 for golf club head and method of manufacture.
Invention is credited to Burnett, Michael Scott, De Shiell, Drew T., Vincent, Benoit.
Application Number | 20040116207 10/316453 |
Document ID | / |
Family ID | 32505950 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040116207 |
Kind Code |
A1 |
De Shiell, Drew T. ; et
al. |
June 17, 2004 |
Golf club head and method of manufacture
Abstract
The present invention resides in a golf club head having a high
COR that is durable and has desirable acoustic qualities. The club
head includes a body portion, a striking face and a crown forming a
hollow cavity of at least 150 cc in volume. The body portion
defines a front opening and an upper opening, and it includes a
sole and a side section that extends rearward of the front opening.
The striking plate is secured to the body portion, enclosing the
front opening. While partially assembled, final weighting and/or
other attachment of other members to the inner surface of the club
head can be preformed, as desired. The crown is secured to the body
portion, enclosing the upper opening. The crown has a maximum
thickness no greater than about 2 mm. The density of the crown is
less than the density of the body portion. At least one of the
striking plate and the crown is attached to the second portion by
adhesive bonding, and the golf club head has a maximum coefficient
of restitution of at least 0.80.
Inventors: |
De Shiell, Drew T.; (San
Diego, CA) ; Burnett, Michael Scott; (Carlsbad,
CA) ; Vincent, Benoit; (Leucadia, CA) |
Correspondence
Address: |
SHEPPARD, MULLIN, RICHTER & HAMPTON LLP
333 SOUTH HOPE STREET
48TH FLOOR
LOS ANGELES
CA
90071-1448
US
|
Family ID: |
32505950 |
Appl. No.: |
10/316453 |
Filed: |
December 11, 2002 |
Current U.S.
Class: |
473/345 ;
473/349 |
Current CPC
Class: |
A63B 53/0437 20200801;
A63B 53/0408 20200801; A63B 53/0412 20200801; A63B 53/0458
20200801; A63B 2209/023 20130101; A63B 53/0466 20130101; A63B 60/00
20151001 |
Class at
Publication: |
473/345 ;
473/349 |
International
Class: |
A63B 053/04 |
Claims
We claim:
1. A golf club head, comprising: a body portion defining an upper
opening and a front opening and having a sole and a side section,
the side section extending rearward of the front opening and having
toe, rear and heel regions, the body portion having a density of at
least about 4 g/cc; a striking plate securely attached to the body
portion, enclosing the front opening; and a crown securely attached
to the body portion, enclosing the upper opening, the crown having
a density between 1 g/cc and 2 g/cc and having a maximum thickness
no greater than about 2 mm, wherein at least one of the striking
plate and the crown is attached to the body portion by adhesive
bonding, the golf club head having a maximum coefficient of
restitution of at least 0.80 and a volume of at least 150 cc.
2. A golf club head as defined in claim 1, wherein the body portion
is integrally formed by a metal casting method.
3. A golf club head as defined in claim 1, wherein the striking
plate is formed of a metal material and is welded to the body
portion.
4. A golf club head as defined in claim 3, wherein a rear surface
of the striking plate has an attachment placed thereon after the
striking plate is welded to the body portion and before the crown
is adhesively bonded to the body portion.
5. A golf club head as defined in claim 1, wherein an inner surface
of the sole has an attachment placed thereon after the striking
plate is attached to the body portion and before the crown is
attached to the body portion.
6. A golf club head as defined in claim 1, wherein the body portion
includes a support surrounding the upper opening for adhesive
bonding of the crown to the body portion.
7. A golf club head as defined in claim 1, wherein each of the body
portion, the striking plate and the crown are formed of different
material.
8. A golf club head as defined in claim 7, wherein two of the body
portion, the striking plate and the crown are formed of different
alloys of the same metal.
9. A golf club head as defined in claim 1, wherein two of the body
portion, the striking plate and the crown are formed of composite
materials that are attached to the remaining non-composite portion
by epoxy adhesive.
10. A golf club head as defined in claim 1, wherein at least one of
the body portion, the striking plate and the crown is formed of at
least two materials.
11. A golf club head as defined in claim 10, wherein the body
portion includes a cast titanium alloy having a higher density
weight attached thereto.
12. A golf club head as defined in claim 1, wherein a weight pad
substantially equal to the weight savings provided by the crown is
provided on the body portion.
13. A golf club head as defined in claim 1, wherein the crown is
formed of a graphite-epoxy composite having a 50% to 70% fiber
volume ratio and a density of 1.4 to 1.65 g/cc.
14. A golf club head as defined in claim 1, wherein the crown is
formed of nylon material having a density ranging between 1 g/cc
and 1.7 g/cc.
15. A golf club head as defined in claim 1, wherein the crown is
formed of polyphenylene sulfide material having a density ranging
between 1.3 g/cc and 2 g/cc.
16. A golf club head as defined in claim 1, wherein the volume is
at least 350 cc.
17. A golf club head, comprising: a body portion defining an upper
opening and a front opening and having a sole and a side section,
the side section extending rearward of the front opening and having
toe, rear and heel regions, the body portion having a density of at
least about 4 g/cc; a striking plate securely attached to the body
portion, enclosing the front opening; and a crown securely attached
to the body portion, enclosing the upper opening, the crown being
formed of plies of composite material having a fiber area weight of
between 20 g/m.sup.2 and 200 g/m.sup.2 and having a maximum
thickness no greater than about 2 mm, the weight of the crown being
less than the weight of a similar sized piece formed of the
material of the body portion; wherein at least one of the striking
plate and the crown is attached to the body portion by adhesive
bonding, the golf club head having a maximum coefficient of
restitution of at least 0.80 and a volume of at least 150 cc.
18. A golf club head as defined in claim 17, wherein the crown is
formed of an uppermost fabric ply and at least one layer of four
plies of uni-tape standard modulus composite, the plies of uni-tape
oriented at 0.degree., +45.degree., -45.degree. and 90.degree..
19. A golf club head as defined in claim 17, wherein the crown is
formed of an uppermost ply of uni-tape standard modulus composite
oriented at 0.degree. or 90.degree., the ply of uni-tape being
painted along with a top section of the body portion.
20. A golf club head as defined in claim 17, wherein the crown is
formed of an uppermost ply of woven graphite cloth oriented at
0.degree. or 90.degree.
21. A method of manufacturing a hollow golf club head having a
volume of at least 150 cc, comprising the steps of: forming a body
of a metal material, the body having walls forming a front that
defines a front opening, a side section, a sole and a top section
that defines an upper opening, forming a striking plate adapted to
be secured to the body and enclose the front opening; securely
attaching the striking plate to the body, enclosing the front
opening; forming a crown of a material having a density less than 2
g/cc, the crown having a maximum thickness no greater than 2 mm,
the crown adapted to be secured to the body, enclosing the upper
opening; and securely attaching the crown to the body, enclosing
the upper opening; wherein at least one of the crown and the
striking plate is attached by adhesive bonding to the opening in
the body, the golf club head having a maximum coefficient of
restitution of at least 0.80.
22. A method as defined in claim 21, wherein the step of forming
the body comprises casting a metal material, the front and upper
openings are formed in the casting step.
23. A method as defined in claim 21, wherein the step of forming
the striking plate comprises cold-forming a metal material to the
desired thickness, shape and size, and the step of attaching the
striking plate comprises welding.
24. A method as defined in claim 21, wherein the step of forming
the striking plate comprises forming a composite plate, and the
step of attaching the striking plate comprises adhesive bonding to
a support at the front opening of the body.
25. A method as defined in claim 21, wherein the step of forming
the crown comprises forming an uppermost ply and at least one layer
of four plies of uni-tape standard modulus graphite.
26. A method as defined in claim 21, further comprising the step of
attaching a member to a rear of the striking plate after the
striking plate has been attached and before the crown has been
attached.
27. A method as defined in claim 21, further comprising the step of
attaching a member to an inner surface of the body after the
striking plate has been attached and before the crown has been
attached.
Description
FIELD OF THE INVENTION
[0001] The invention relates generally to a wood-type golf club
head and, more particularly, to a golf club head having a non-metal
crown.
BACKGROUND OF THE INVENTION
[0002] A wood-type golf club head includes a load-bearing outer
shell with an integral or attached strike plate. Today's club head
is typically formed of metal material and has a hollow cavity. The
metal body may comprise several portions welded together or may
include a cast body with a separate sole plate or strike plate that
is welded in the appropriate location.
[0003] Most club heads today are made of a strong, yet lightweight
material such as, for example, a titanium, steel or aluminum alloy.
There have also been heads formed of carbon fiber composite
material. The use of these materials is advantageous for the larger
club heads now sought by golfers, i.e., at least 300 cc and up to
about 500 cc in volume. The larger sized, yet conventionally
weighted, club heads strive to provide larger "sweet spots" on the
striking face and club moments of inertia that, for some golfers,
make it easier to get a golf ball up in the air and with greater
accuracy.
[0004] Various attempts have been made to attain an improved
coefficient-of-restitution ("COR") for golf club heads, with much
attention paid to the design of face plates having variable
thicknesses. However, the durability of very thin portions of the
face plate continues to be a problem. Such face plate designs are
limited by the high impact loads to which these club heads are
subject, in particular at the junctions of the face plate with the
crown and sole of the club head.
[0005] Titanium alloys are particularly favored in club head
designs for their combination of strength and light weight.
However, the material can be quite costly. Steel alloys are more
economical; however, since the density of steel alloys is greater
than for titanium alloys, steel club heads are limited in size in
order to remain within conventional head weights while maintaining
durability.
[0006] Composite club heads, such as a carbon fiber reinforced
epoxy or carbon fiber reinforced polymer, for example, are an
alternative to metal club heads. A notable advantage is the
relatively light weight compared to stainless steel alloys.
However, these club heads have suffered from durability and
performance qualities associated with composite materials. These
include higher labor costs in manufacture, undesirable acoustic
properties of the composite material, shearing and separation of
the layers of composite plies used to form the striking surface of
the club head and relatively low COR for composite faces.
[0007] The areas of the club head that are subject to the greatest
wear, the face and sole, have been reinforced in some instances by
providing a metal plate in one or both regions. Integrated face and
hosel constructions have also been done. However, durability at the
junctions of the composite and metal materials continues to be a
problem. Further, when the majority of the body of the club head is
of composite material, there may still remain the problem of
adequately fixing one or more weighting elements within the head
body. The mere increase in volume of the club head may not provide
the proper location of the center of gravity of the club head for
greater forgiveness in off-center hits.
[0008] With regard to hybrid metal-composite club heads, U.S. Pat.
Nos. 5,328,176, 5,410,798, and 5,624,331 to Kun-Nan Lo disclose
composite-metal golf club heads having a metal casing with an inner
member or core of composite material. The inner member reinforces
the thin walls of the metal casing in U.S. Pat. Nos. 5,410,798 and
5,624,331. The crown comprises one or two carbon fiber composite
portions. The single composite crown portion of U.S. Pat. No.
5,410,798 is attached to the upper ends of the composite member
during the heating portion of the manufacturing process. The double
composite crown portions of U.S. Pat. No. 5,624,331 are separated
by a reinforcing central rib of the metal casing. U.S. Pat. No.
5,328,176 discloses a metal reinforcing plate that is fixed to the
front face and wraps around the composite head from front to
back.
[0009] Published U.S. Patent Application No. 2002/0049310 to Cheng
et al. discloses a metal golf club head having a carbon-fiber cover
that incorporates the entirety of the upper wall and a majority of
the side walls at the toe, rear and heel ends of the head body. The
position of the center of gravity of the head is accomplished by
the size and placement of weight plugs in the sole and rear side
wall. The attachment of the carbon-fiber cover is accomplished by
insertion of a bladder through the hole for the plug in the sole
and application of aluminum oxide sand where the carbon-fiber cover
contacts the metal base and face of the head. The bladder is
inflated, and the aluminum-oxide sand adhesively attaches the cover
to the rest of the club head during a heating process.
[0010] Published Japanese Application No. 05-317465 discloses a
golf club head having a hole cut into the crown part. The hole may
be closed with a plate of a transparent and lightweight resin. This
device allows the weight of the replaced metal material to be
substantially distributed to the sole, lowering the center of
gravity. An initial speed of a ball is increased and an amount of
spin can be decreased, whereby distance can be increased.
[0011] Metal, composite and hybrid metal-composite club heads have
long suffered from poor acoustic properties. That is, golfers are
accustomed to--and desire--a particular range in pitch tone
generated by the golf ball impacting the striking face. Some prior
club heads have used a foam filling in order to alter the sound
while attempting to minimize any adverse impact on performance.
While metal club heads have become better matched to golfers'
acoustic preferences, composite club heads generally lack acoustic
appeal.
[0012] It should, therefore, be appreciated, there is a need for a
golf club head having a high COR and improved durability and
acoustic qualities, which is cost effective and simple to
manufacture. The present invention fulfills this need and
others.
SUMMARY OF THE INVENTION
[0013] The present invention provides a golf club head having a
high COR that is durable and has desirable acoustic qualities. The
club head includes a body portion, a striking face and a crown
forming a hollow cavity of at least 150 cc in volume. The body
portion defines a front opening and an upper opening, and it
includes a sole and a side section that extends rearward of the
front opening. The striking plate is secured to the body portion,
enclosing the front opening. The crown is secured to the body
portion, enclosing the upper opening. The crown has a maximum
thickness no greater than about 2 mm. The density of the crown is
less than the density of the body portion. At least one of the
striking plate and the crown is attached to the second portion by
adhesive bonding, and the golf club head has a maximum coefficient
of restitution of at least 0.80.
[0014] In a detailed aspect of a preferred embodiment, the body
portion is preferably formed of a metal having a density of at
least about 1.8 g/cc and preferably at least about 4 g/cc. The
crown has a density between 1 g/cc and 2 g/cc.
[0015] In another detailed aspect of a preferred embodiment, the
crown may be formed of plies of composite material having a fiber
area weight of between 20 g/m.sup.2 and 200 g/m.sup.2. The weight
of the composite crown being at least 20% less than the weight of a
similar sized piece formed of the metal of the body. The composite
crown may be formed of an uppermost ply and at least one layer of
four plies of uni-tape standard modulus graphite, the plies of
uni-tape oriented at 0.degree., +45.degree., -45.degree. and
90.degree..
[0016] In yet another detailed aspect of a preferred embodiment,
the striking plate is separately formed and attached to the front
of the body of the club head. At least one of the crown and
striking plate is adhesively attached to the main body of the club
head. The striking plate is made of metal and is welded to a cast
second portion of the body having an opening at its front, with a
lightweight crown adhesively bonded to the top opening of the
body.
[0017] A method of manufacturing a golf club head having a maximum
coefficient of restitution of at least 0.80 is also provided. The
method includes forming a body potion of a metal material, the body
having walls forming a front, a side section, a sole and a top
section, an opening formed in each of the front and the top
section. A striking plate adapted to enclose the front opening of
the body is also formed. A crown is formed to enclose the opening
in the top section. The crown has a density less than 2 g/cc and a
maximum thickness no greater than 2 mm. The striking plate is
attached to the body portion, enclosing the front opening. At least
one of the crown and the striking plate is attached to the body by
adhesive bonding. The forming steps may be performed in any order,
while the striking plate is attached prior to attachment of the
crown to the body. The resulting access to the interior of the
nearly complete golf club head allows final weighting and/or other
members to be attached to any inner surface as desired.
[0018] For purposes of summarizing the invention and the advantages
achieved over the prior art, certain advantages of the invention
have been described herein above. Of course, it is to be understood
that not necessarily all such advantages may be achieved in
accordance with any particular embodiment of the invention. Thus,
for example, those skilled in the art will recognize that the
invention may be embodied or carried out in a manner that achieves
or optimizes one advantage or group of advantages as taught herein
without necessarily achieving other advantages as may be taught or
suggested herein.
[0019] All of these embodiments are intended to be within the scope
of the invention herein disclosed. These and other embodiments of
the present invention will become readily apparent to those skilled
in the art from the following detailed description of the preferred
embodiments having reference to the attached figures, the invention
not being limited to any particular preferred embodiment(s)
disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Embodiments of the present invention will now be described,
by way of example only, with reference to the following drawings in
which:
[0021] FIG. 1 is a partially exploded perspective view of a
preferred embodiment of a club head in accordance with the
invention, depicting a crown separated from a body portion.
[0022] FIG. 2 is a cross-sectional view of the club head of FIG. 1,
depicting the crown in place.
[0023] FIG. 3 is a cross-sectional view a junction of the crown and
body portion of the club head of FIG. 1.
[0024] FIG. 4 is a cross-sectional view of a second preferred
embodiment of a golf club head in accordance with the
invention.
[0025] FIG. 5 is a cross-sectional view of a junction of the crown
and the body portion of the club head of FIG. 4.
[0026] FIG. 6 is a partially exploded view of another preferred
embodiment of a club head in accordance with the invention,
depicting the composite crown separated from the metal body.
[0027] FIG. 7 is a perspective view of a striking face and a body
portion of a preferred embodiment of a golf club head in accordance
with the invention, depicting a rear surface of the striking
face.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] With reference to the illustrative drawings, and
particularly FIG. 1, there is shown a golf club head 10 having a
crown 12 formed of composite material not yet attached to a body 14
of a golf club head, to enclose an opening 16. The body is formed
of any metal, such as an aluminum, steel or titanium alloy, for
example. The body may be cast to form a front 18, a sole 20, a top
portion 22 and a side portion 24. At the front, a striking plate 26
is separately formed and attached to the front of the body in any
manner known to those skilled in the art (see FIGS. 4 and 5). The
striking plate may be formed of a different alloy or grade of the
same metal as the body, or the plate may be a different metal or a
composite material, as desired. If metallic, the striking plate is
welded to the front 18; if made of a composite material, the
striking plate may be adhesively bonded to the front 18.
[0029] In alternative embodiments, the metal body may comprise
three or more portions welded together, where the portions are
forged, cast or stamped pieces or any mix thereof. Or, the body may
be cast except for a separate sole plate that is attached in the
appropriate location. The body may also include one or more
attached members, such as weighting elements, that may comprise a
metal or other material having a different density than the
material of the rest of the main body.
[0030] The side portion 24 extends rearwardly of the front 18 and
has a toe region 28, a rear region 30 and a heel region 32 formed
above the sole 20. A hosel 34 is provided at the heel end of the
body for attachment of a shaft (not shown). The top portion 22 of
the body 14 extends rearwardly from an upper edge 36 of the front
18 of the club head, above the side portion 24. Thus, the sole 20,
top portion 22, front 18 and side portion combine with the crown 12
to form a hollow body having a volume of at least 150 cubic
centimeters (cc) and up to 500 cc.
[0031] As more clearly shown in FIG. 2, the cast body 14 includes
an annular rim 38 at the opening 16 in the top portion 22 that
includes a ledge 40 that acts as a support member for the crown 12.
Alternatively, the support member may comprise a plurality of tabs.
The size and shape of the support member is preferably chosen to
minimize the required overlap with the crown or the mating surface
area of the crown and top portion.
[0032] Referring to FIG. 3, the rim 38 extends a distance D.sub.1
of at least 7 mm rearward from the upper edge 36 of the front 18,
with a shoulder 42 defining the ledge 40 which preferably extends
an additional distance D.sub.2 of at least 7 mm. The rim preferably
extends between 8 mm and 12 mm, and more preferably about 10 mm,
from the upper edge 36 while providing advantages of the present
invention. Similarly, the ledge preferably extends between 8 mm and
12 mm. Preferably, an adhesive such as Hysol.RTM. two part epoxy
9460 or, alternatively, 3M.RTM. DP460NS, is used to attach the
crown 12 onto the ledge 40, abutting the shoulder 42.
[0033] The opening 16 in a central section 44 of the top portion 22
comprises at least 25% (see FIG. 6), and preferably comprises at
least 60%, of the total area of the top portion 22. More
preferably, the opening is at least 75% of the total area of the
top portion. Thus, there is a significant weight savings afforded
by replacing a similarly sized metal crown with the crown 12
described herein. The difference in weight between the metal and
composite materials may be redistributed in the club head 10 to
manipulate the center of gravity of the club head, such as by
providing a weight pad 46 on an interior surface 48 of the sole as
shown in FIG. 4. Such a weight pad is preferably formed of a softer
metal of lower density than the material of the body 14 of the club
head and is attached to the sole 20; although, a weight pad may
alternatively be cast as a thickened portion of the sole.
[0034] Tables I and II show exemplary materials for the body 14 of
the club head and the crown 12, respectively. The body 14
preferably has a thin-wall construction, wherein the thicknesses of
the sole 20 and side portion 24 is in the range of 0.8 mm to 2 mm
and the top portion thickness is in the range of 0.7 mm to 2 mm.
The thickness of the front portion 16 is preferably in the range of
1.5 mm to 4 mm. The crown is also of a thin construction, having a
thickness T.sub.c of no more than about 2 mm, preferably less than
1.5 mm, and more preferably about 1 mm. In the preferred embodiment
of FIGS. 1-3, the thickness of the top portion 22, including the
ledge 40, is approximately 1 mm so that the shoulder 42 extends
about 2 mm from an outer surface 50 of the top portion to an inner
surface 52 of the ledge.
1TABLE I EXAMPLES OF METALS FOR THE BODY OF A CLUB HEAD Ult. Mod.
Density Tens. Str. of Elast. Material Type (g/cc) (MPa) (GPa)
Hardness Mg AZ81A-T4 1.8 275 45 Brinell 55 Al 1201 Alloy 2.85 430
72 -- Ti 6A1-4V 4.43 950 113.8 Brinell 334 Rockwell C 36 Ti
15-3-3-3 4.76 790 82 Rockwell B 95 Carpenter 7.76 1100 200 Brinell
318 Custom 455 .RTM. Rockwell C 34
[0035]
2TABLE II EXAMPLES OF COMPOSITE MATERIALS FOR A CLUB HEAD CROWN
Ult. Tens. Density Str. Modulus of Composite Fiber Material (g/cc)
(MPa) Elasticity (GPa) Thornel .RTM. Graphite Cloth 1.4 103 13
DuPont Kevlar .RTM. 49 Fiber, 1.44-1.45 2760 120-125 diam 11.9 um
Thornel .RTM. VCB-20 Carbon 1.88 1380 138 Cloth
[0036] A graphite-epoxy composite material, for example, with a 50%
to 70% fiber volume ratio would have a density between about 1.4
g/cc and 1.65 g/cc.
[0037] A golf club head constructed in this manner advantageously
improves durability since the junction of the striking plate 26
with the top portion 22 is subject to a lesser force at impact with
a golf ball. The use of the crown 12 on the metal body 14 also
increases COR. Further, the golf club head having a crown on a
metal body advantageously provides acoustic qualities judged to be
more appealing to golfers.
[0038] In one club head tested by the inventors, a 300 cc hollow
body was formed of a stainless steel alloy. A large area, 1 mm
thick crown was formed of 5 plies including 4 plies of a uni-tape
of standard modulus graphite and 1 ply of a woven graphite cloth.
The 4 plies of uni-tape were assembled at 0, 45, -45 and 90 degrees
and had a fiber area weight (FAW) of about 140 grams per meter
squared (g/m.sup.2). The standard modulus is approximately 33 Mpsi
for the fiber with about 600 Kpsi tensile strength. In comparison,
an alternative, and more expensive, ultrahigh modulus fiber
(satellite grade) comprises about 57 Mpsi. FAW may range from about
20 to 200 g/m.sup.2, and preferably the composite plies for the
crown are in the range of 70 to 180 g/m.sup.2. More preferably, the
composite plies for the crown are in the range of 120 to 160
g/m.sup.2.
[0039] The resultant mass of the crown 12 is about 10 grams. This
is about a 50% reduction in the mass compared to a crown formed of
the steel material of the rest of the club head. The calculations
of the weight savings must take into account the presence of the
ledge 40 with the crown, as well as the adhesive. Generally, the
weight savings is at least 20% compared to an all metal body. The
weight pad 46 may then be added to achieve a total mass
approximately equivalent to an all metal body.
[0040] The crown 12 may alternatively be formed of more or less
plies, and instead of the top ply being a woven graphite cloth, the
top ply may be another uni-tape that is painted to achieve the
desired aesthetic look of the club head. The top ply is preferably
oriented at 0 or 90 degrees. The molding of the crown may be
performed using methods known to those skilled in the art and
preferably comprises a dual mold to achieve a net shape that
requires little finishing and flash removal prior to its attachment
to the body 14 of the club head.
[0041] Another club head tested by the inventors utilized a
titanium alloy body for the club head, with a crown 12 formed of a
thermoplastic material. Preferably, the crown is an
injection-molded nylon or polyphenylene sulfide (PPS) material,
using 3M.RTM. DP460NS adhesive for attachment to the metal body.
The nylon may be used with or without glass or carbon fiber and
preferably has a density between 1 g/cc and 1.7 g/cc.
Alternatively, the PPS material maybe used with or without glass or
carbon fiber and preferably has a density between 1.3 g/cc and 2.0
g/cc. Replacing the crown of the titanium alloy club head results
in about a 35% savings in weight. In general, the weight savings is
at least 15% compared to an all metal body.
[0042] The replacement of the crown of a metal club head provides
the advantage of weight savings and/or redistribution of mass to
the sole, for example. A weight pad on the sole, or elsewhere on
the body, may be integrally formed or be a separately formed and
attached mass, the resulting weight being comparable to an all
metal club head of the same volume.
[0043] Because of the access afforded by the opening in the top of
the club head, a rear of the striking face 54 is accessible during
manufacture for the addition of a face reinforcing member 56 formed
of metal or composite material and securely attached behind the
sweet spot, as shown in FIG. 7. Thus, a thin titanium alloy
striking face can be strengthened or otherwise enhanced in
performance. Similarly, any number of additional members may be
attached elsewhere on any inner surface of the club head.
[0044] The use of the aforementioned materials, composite or
plastic, for the crown 12 allows the use of a lighter weight
material that may result in the top of the club head having a
stiffness similar to the heavier, metal sole. This stiffness
matching may be advantageous for high COR golf club heads.
[0045] The golf club head 10 can be assembled with the aid of
adhesive bonding. In a preferred method of manufacture, the
striking face 22 is securely attached to the body 14, enclosing a
front opening. While partially assembled, final weighting and/or
other attachment of other members to the inner surface of the club
head can be preformed, as desired. Next, the crown is secured in
place, forming the top section of the club head. Preferably, the
crown 12 is of a material having a density less than 2 g/cc has a
thickness no greater than 2 mm. At least one of the crown and the
striking plate is attached by adhesive bonding to the opening in
the body. In one embodiment, the mating surfaces of the crown and
ledge 40 may be prepared by sandblasting to enhance bonding. Other
steps may be performed in order to prepare and/or finish the final
club head, as known to those skilled in the art.
[0046] Although the invention has been disclosed in detail with
reference only to the preferred embodiments, those skilled in the
art will appreciate that additional golf club heads can be made
without departing from the scope of the invention. Accordingly, the
invention is only by the claims set forth below.
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