U.S. patent application number 14/099748 was filed with the patent office on 2014-05-29 for golf club head with multi-material face.
This patent application is currently assigned to Acushnet Company. The applicant listed for this patent is Acushnet Company. Invention is credited to John W. Morin, Mark C. Myrhum.
Application Number | 20140148271 14/099748 |
Document ID | / |
Family ID | 50773768 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140148271 |
Kind Code |
A1 |
Myrhum; Mark C. ; et
al. |
May 29, 2014 |
GOLF CLUB HEAD WITH MULTI-MATERIAL FACE
Abstract
A metal wood golf club with a striking face portion made from
more than one material is disclosed. More specifically, due to the
unique construction of the striking face portion having multiple
materials, the present invention utilizes diffusion bonding, liquid
interface diffusion, or even super plastic forming techniques to
achieve the desirable bond between the more than one material used
to form the striking face. The different materials could even be
the same base material with different compositions as long as they
have different Young's modulus.
Inventors: |
Myrhum; Mark C.; (Del Mar,
CA) ; Morin; John W.; (Poway, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Acushnet Company |
Fairhaven |
MA |
US |
|
|
Assignee: |
Acushnet Company
Fairhaven
MA
|
Family ID: |
50773768 |
Appl. No.: |
14/099748 |
Filed: |
December 6, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13596271 |
Aug 28, 2012 |
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14099748 |
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13207344 |
Aug 10, 2011 |
8409032 |
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13596271 |
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Current U.S.
Class: |
473/342 |
Current CPC
Class: |
A63B 53/0466 20130101;
A63B 53/0462 20200801; A63B 53/0458 20200801; A63B 53/04 20130101;
A63B 53/0425 20200801; A63B 2209/00 20130101; A63B 60/00
20151001 |
Class at
Publication: |
473/342 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Claims
1. A golf club head comprising: a striking face portion located at
a frontal portion of said golf club head; and a body portion
attached to an aft portion of said striking face portion; wherein
said striking face portion further comprises; a first titanium
material, and a second titanium material; wherein said second
titanium material has a higher Young's modulus than said first
titanium material.
2. The golf club head of claim 1, wherein said first titanium
material may generally have a Young's modulus of less than about
110 GPa.
3. The golf club head of claim 2, wherein said first titanium
material may have a Young's modulus of less than about 105 GPa.
4. The golf club head of claim 3, wherein said first titanium
material may have a Young's modulus of less than about 100 GPa.
5. The golf club head of claim 2, wherein said second titanium
material may generally have a Young's modulus of greater than about
110 GPa.
6. The golf club head of claim 5, wherein said second titanium
material may generally have a Young's modulus of greater than about
115 GPa.
7. The golf club head of claim 6, wherein said second titanium
material may generally have a Young's modulus of greater than about
120 GPa.
8. The golf club head of claim 1, wherein said first titanium
material and said second titanium material are joined together
using diffusion bonding.
9. The golf club head of claim 1, wherein said first titanium
material and said second titanium material are joined together
using liquid interface diffusion bonding.
10. The golf club head of claim 1, wherein said first titanium
material and said second titanium material are joined together
using super plastic forming.
11. A golf club head comprising: a striking face portion located at
a frontal portion of said golf club head; and a body portion
attached to an aft portion of said striking face portion; wherein
said striking face portion further comprises; a first titanium
material, and a second titanium material; wherein said first
titanium material and said second titanium material are joined
together using diffusion bonding.
12. The golf club head of claim 11, wherein first titanium material
may generally have a Young's modulus of less than about 110
GPa.
13. The golf club head of claim 12, wherein said first titanium
material may have a Young's modulus of less than about 105 GPa.
14. The golf club head of claim 13, wherein said first titanium
material may have a Young's modulus of less than about 100 GPa.
15. The golf club head of claim 12, wherein said second titanium
material may generally have a Young's modulus of greater than about
110 GPa.
16. The golf club head of claim 15, wherein said second titanium
material may generally have a Young's modulus of greater than about
115 GPa.
17. The golf club head of claim 16, wherein said second titanium
material may generally have a Young's modulus of greater than about
120 GPa.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a Continuation-In-Part of
co-pending U.S. patent application Ser. No. 13/596,271, filed on
Aug. 28, 2012, which is a Continuation-In-Part of U.S. patent
application Ser. No. 13/207,344, filed Aug. 10, 2011, the
disclosure of which are all incorporated by reference in their
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a golf club head
having a striking face portion made from more than one material.
More specifically, the present invention relates to a metalwood
type golf club head wherein a secondary material is used to form a
chip insert to be placed in a cavity formed away from the geometric
center of the striking face portion of the golf club head; wherein
the secondary material could have higher or even lower modulus when
compared to the remainder of the striking face. The striking face
portion, due to the unique construction, may generally be formed
together using diffusion bonding, liquid interface diffusion, or
super plastic forming techniques to achieve the desired bond
strength. The metalwood type golf club head, by incorporating a
secondary material around a geometric center of the striking face
portion, improves the overall performance of the golf club head by
either significantly increasing the size of the sweet spot of a
golf club head or dramatically increasing the coefficient of
restitution.
BACKGROUND OF THE INVENTION
[0003] In order to perform well in the game of golf, a golfer needs
to be able to execute a variety of different golf shots; with each
one of them focusing on a different aspect of the golf game. For
example, in order to execute a good chip and or pitch shot, a
golfer needs to be able to control the trajectory, distance, and
spin of a golf ball for the golf ball to come to rest at a location
that is as close to the pin as possible; or more preferably in the
hole. In another example, in order to execute a good iron shot, a
golfer needs to control the distance and dispersion of the golf
shot to ensure that it lands on the green; sacrificing some
accuracy in an attempt to achieve distance gains. Finally, in
another example, in order to execute a good driver shot, a golfer
needs to maximize the distance of the golf shot while maintaining a
relatively straight flight path. Based on the above, it can be seen
that as the clubs get longer and longer, less and less emphasis is
placed on accuracy, and more and more emphasis is placed on
distance.
[0004] With respect to drive type shots, golf club designers have
always attempted to design wood type golf clubs that increases the
overall distance of the golf shot while maintaining a relatively
straight flight path. U.S. Pat. No. 6,932,716 shows one attempt of
increasing the overall distance of a driver type golf club by
increasing the coefficient of restitution of the driver type golf
club head. More specifically U.S. Pat. No. 6,932,716 attempts to
achieve this by creating a golf club head having a matrix layer
composed of an interconnected reinforcement structure and a polymer
material, wherein the matrix layer provides the golf club head with
a greater coefficient of restitution during impact with a golf
ball. U.S. Pat. No. 6,719,644 provides another example of
increasing the distance of a driver type golf club head by using
shallow markings that prevent stress fracture, resulting in a
thinner face that provides improved coefficient of restitution.
[0005] In order to help golfers maintain a relative straight flight
path in a drive type golf shot, golf club designers have attempted
to create larger club heads that results in an increase in the
moment of inertia of these oversized club heads; as an increase in
the moment of inertia prevents the clubhead from undesirable
twisting at impact that could send a golf shot off the intended
path. U.S. Pat. No. 7,413,520 provides one example of increasing
the overall size of the golf club head to help a golfer hit a ball
straighter. More specifically, U.S. Pat. No. 7,413,520 discloses a
golf club head having a volume ranging from 450 cubic centimeters
to 475 cubic centimeters, a mass ranging from 180 grams to 225
grams, and a front to back length ranging from 4.0 inches to 5.0
inches. Moreover, U.S. Pat. No. 7,413,520 also illustrates one of
the incidental effects is an increase in the moment of inertia,
Iyy, about the center of gravity of the golf club head achieving
numbers greater than 4000 grams-centimeters squared.
[0006] Although increasing the coefficient of restitution and the
moment of inertia of a golf club head both help a golfer hit a golf
ball longer and straighter, they are not the be all and end all in
achieving longer and straighter drives. In fact, the size of the
sweet spot is another one of those factors that can make a
significant difference, but is often overlooked. U.S. Pat. No.
5,839,975 identifies the importance of the sweet spot by creating a
golf club head with a rib structure within the internal cavity of
the golf club head to reinforce the club head to prevent collapse
or other distortion while providing a relatively large sweet spot.
Although U.S. Pat. No. 5,839,975 provides one of the earlier
attempts of identifying and increasing the size of the sweet spot
of a golf club head, it does so by adding additional material to
the internal cavity of the golf club head, which can often be
undesirable. In order to achieve the same goal without adding
weights, a golf club designer could potentially use different
materials to form the striking face.
[0007] U.S. Pat. No. 3,975,023 shows an early attempt at the usage
of multiple different materials at or near the striking face
portion of the golf club head, however, it does so in an attempt to
increase the overall flying distance of a golf ball, and makes no
mention of increasing the size of the sweet spot. U.S. Pat. No.
3,795,023 discloses a golf club that fixes the striking face of the
club head with a ceramic face plate made of a sintered body of
metallic oxides such as alumina ceramics, mullite ceramics,
etc.
[0008] U.S. Pat. No. 7,874,938 provides a more modern attempt to
use multiple different materials by using composite articles on the
face plate. More specifically, U.S. Pat. No. 7,874,938 discloses a
golf club head having a composite face plate, wherein the composite
face plate can be made by first forming an oversized lay-up of
multiple prepreg plies having a central portion and a sacrificial
portion surrounding the central portion. The lay-up is at least
partially cured in a mold under elevated pressure and heat, then
the lay-up is then removed from the mold and the sacrificial
portion is removed from the central portion to form a composite
part that is substantially free of defects. However, similar to
U.S. Pat. No. 3,975,023, U.S. Pat. No. 7,874,938 makes no mention
of the ability to increase the sweet spot of a golf club head.
[0009] Hence, it can be seen from above, despite all the
development in recognizing the importance of increasing the size of
the sweet spot, the current art is incapable of achieving
improvements in sweet spot size without adding undesirable weight.
On the other hand, the only attempts of using multiple materials at
the striking face without increasing weight fails to incorporate a
design that could increase the size of the sweet spot. Hence, there
is a need in the art for a golf club head that is capable of
utilizing multiple materials in a way that can increase the size of
the sweet spot of a golf club head.
BRIEF SUMMARY OF THE INVENTION
[0010] In one aspect of the present invention is a golf club head
comprising a striking face portion, located at a frontal portion of
the golf club head, and a body portion attached to an aft portion
of the striking face portion. The striking face portion further
comprises a first outer layer, made out of a first material, a
second backing layer, made out of a similar material as the first
outer layer, and a chip insert, made out of second material. The
first outer layer forms an exterior surface of the striking face
portion and the second backing layer forms an interior surface of
the striking face portion wherein the first outer layer and the
second backing layer combine to form a cavity substantially near a
geometric center of the striking face portion. The chip insert is
placed within the cavity, wherein the striking face portion has a
Face Thickness Ratio of less than about 0.875, the Face Thickness
Ratio is defined as a thickness of the first outer layer at the
geometric center divided by a thickness of the second backing layer
at the geometric center.
[0011] In another aspect of the present invention is a golf club
head comprising a striking face portion, located at a frontal
portion of the golf club head, and a body portion attached to an
aft portion of the striking face portion. The striking face portion
further comprises a first outer layer, made out of a first
material, a second backing layer, made out of a similar material as
the first outer layer, and a chip insert, made out of second
material. The first outer layer forms an exterior surface of the
striking face portion and the second backing layer forms an
interior surface of the striking face portion wherein the first
outer layer and the second backing layer combine to form a cavity
substantially near a geometric center of the striking face portion.
The chip insert is placed within the cavity, wherein the first
material is different from the second material, and the second
material has a Young's modulus that is greater than a Young's
modulus of the first material.
[0012] In another aspect of the present invention is a golf club
head comprising a striking face portion, located at a frontal
portion of the golf club head, and a body portion attached to an
aft portion of the striking face portion. The striking face portion
further comprises a first outer layer, made out of a first
material, a second backing layer, made out of a similar material as
the first outer layer, and a chip insert, made out of second
material. The first outer layer forms an exterior surface of the
striking face portion and the second backing layer forms an
interior surface of the striking face portion wherein the first
outer layer and the second backing layer combine to form a cavity
substantially near a geometric center of the striking face portion.
The chip insert is placed within the cavity, wherein the striking
face portion is formed using a liquid interface diffusion
process.
[0013] These and other features, aspects and advantages of the
present invention will become better understood with references to
the following drawings, description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The foregoing and other features and advantages of the
invention will be apparent from the following description of the
invention as illustrated in the accompanying drawings. The
accompanying drawings, which are incorporated herein and form a
part of the specification, further serve to explain the principles
of the invention and to enable a person skilled in the pertinent
art to make and use the invention.
[0015] FIG. 1 of the accompanying drawings shows a perspective view
of a golf club head in accordance with an exemplary embodiment of
the present invention;
[0016] FIG. 2 of the accompanying drawings shows a frontal view of
a golf club head in accordance with an exemplary embodiment of the
present invention, allowing cross-sectional lines A-A' to be
shown;
[0017] FIG. 3 of the accompanying drawings shows a cross-sectional
view of a golf club head in accordance with an exemplary embodiment
of the present invention taken along cross-sectional line A-A';
[0018] FIG. 4 of the accompanying drawings shows an exploded view
of a face insert containing a chip insert in accordance with an
exemplary embodiment of the present invention;
[0019] FIG. 5 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with an
exemplary embodiment of the present invention taken at circle C
shown in FIG. 3;
[0020] FIG. 6 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with an
alternative embodiment of the present invention taken at circle C
shown in FIG. 3;
[0021] FIG. 7 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with a
further alternative embodiment of the present invention taken at
circle C shown in FIG. 3;
[0022] FIG. 8 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with an
alternative embodiment of the present invention taken at circle C
shown in FIG. 3;
[0023] FIG. 9 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with an
alternative embodiment of the present invention taken at circle C
shown in FIG. 3;
[0024] FIG. 10 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with an
alternative embodiment of the present invention taken at circle C
shown in FIG. 3;
[0025] FIG. 11 of the accompanying drawings shows an exploded view
of a face insert containing a chip insert in accordance with an
alternative embodiment of the present invention;
[0026] FIG. 12 of the accompanying drawings shows an exploded view
of a face insert containing a chip insert in accordance with an
alternative embodiment of the present invention;
[0027] FIG. 13 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with an
alternative embodiment of the present invention taken at circle C
shown in FIG. 3;
[0028] FIG. 14 of the accompanying drawings shows a an exploded
view of a face insert containing two or more inserts in accordance
with an alternative embodiment of the present invention;
[0029] FIG. 15 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with an
alternative embodiment of the present invention taken a circle C
shown in FIG. 3;
[0030] FIG. 16 of the accompanying drawings shows a cross-sectional
view of a golf club head in accordance with an alternative
embodiment of the present invention;
[0031] FIG. 17 of the accompanying drawings shows a cross-sectional
view of a golf club head in accordance with an alternative
embodiment of the present invention;
[0032] FIG. 18 of the accompanying drawings shows a an exploded
view of a face insert containing two or more inserts in accordance
with an alternative embodiment of the present invention;
[0033] FIG. 19 of the accompanying drawings shows an enlarged
cross-sectional view of a golf club head in accordance with an
alternative embodiment of the present invention taken a circle C
shown in FIG. 3;
[0034] FIG. 20 of the accompanying drawings shows a perspective
view of a golf club head in accordance with an alternative
embodiment of the present invention;
[0035] FIG. 21 of the accompanying drawings shows a perspective
view of a golf club head in accordance with an exemplary embodiment
of the present invention;
[0036] FIG. 22 of the accompanying drawings shows a perspective
view of a golf club head in accordance with an exemplary embodiment
of the present invention;
[0037] FIG. 23 of the accompanying drawings shows a perspective
view of a golf club head in accordance with an exemplary embodiment
of the present invention;
[0038] FIG. 24 of the accompanying drawings shows a perspective
view of a golf club head in accordance with an exemplary embodiment
of the present invention;
[0039] FIG. 25 of the accompanying drawings shows a perspective
view of a golf club head in accordance with an exemplary embodiment
of the present invention; and
[0040] FIG. 26 of the accompanying drawings shows a perspective
view of a golf club head in accordance with an exemplary embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0041] The following detailed description is of the best currently
contemplated modes of carrying out the invention. The description
is not to be taken in a limiting sense, but is made merely for the
purpose of illustrating the general principles of the invention,
since the scope of the invention is best defined by the appended
claims.
[0042] Various inventive features are described below that can each
be used independently of one another or in combination with other
features. However, any single inventive feature may not address any
or all of the problems discussed above or may only address one of
the problems discussed above. Further, one or more of the problems
discussed above may not be fully addressed by any of the features
described below.
[0043] FIG. 1 of the accompanying drawings shows a perspective view
of a golf club head 100 in accordance with an exemplary embodiment
of the present invention. More specifically, FIG. 1 of the
accompanying drawings shows a golf club head 100 having a striking
face portion 102 and a body portion 104. It should be noted that in
this current exemplary embodiment, the striking face portion 102
may further comprise of a face insert 106 to allow the
manufacturers to manipulate the geometry of the rear surface of the
striking face portion 102. However, in order to truly understand
the inventive features of the present invention, one must look into
the cross-sectional view of the striking face portion 102 and/or
the face insert 106 that can show the multiple materials used to
construct the face insert 106. Before diving into a discussion
regarding the multi-material construction of the face insert 106 it
is worthwhile to establish here that although the subsequent
figures will all utilize a face insert 106, the present invention
does not require the usage of a face insert 106; in fact, the
present invention is intended to include any type of multi-material
construction near the striking face portion 102 such as a face cup,
an L-cup, or any other construction without departing from the
scope and content of the present invention.
[0044] In order to show a cross-sectional view of the striking face
102, FIG. 2 of the accompanying drawings shows a frontal view of a
golf club head 200, allowing cross-sectional lines A-A' to be
drawn. In addition to showing the cross-sectional lines A-A', FIG.
2 of the accompanying drawings also shows a geometric center 205 of
the striking face portion 202. The geometric center 205 of the
striking face portion 202 is important to the current invention
because the placement of the secondary material may generally be
substantially behind the geometric center 205 of the striking face
portion 202.
[0045] FIG. 3 of the accompanying drawings shows a cross-sectional
view of a golf club head 300 taken along cross-sectional line A-A'
shown in FIG. 2. The cross-sectional view of golf club head 300
shows the multi-material composition of the striking face portion
302 of the golf club head. More specifically, the striking face
portion 302 further comprises of a first outer layer 310, a second
backing layer 312, and a chip insert 314 juxtaposed or encapsulated
between the first outer layer 310 and the second backing layer 312.
The first outer layer 310, as disclosed in this exemplary
embodiment of the present invention may generally be formed out of
a first material. The first material may generally be a titanium
type material having a Young's modulus of between about 80 GPa to
about 130 GPa, more preferably between about 90 GPa to about 120
GPa, and most preferably between about 95 GPa to about 115 GPa.
However, the first material need not be made out of a titanium
material, and could be made out of any material that is
sufficiently durable to endure the impact forces with a golf ball
without departing from the scope and content of the present
invention.
[0046] First outer layer 310, although shown in FIG. 3 to be a thin
sheet of titanium, can also be created using a sprayed coating type
of titanium without departing from the scope and content of the
present invention. Because it is generally desirable to keep the
thickness of first outer layer 310 as thin as possible to minimize
its size and weight, the present construction can be achieved by
spray coating the front surface of the striking face portion 302 to
significantly reduce the thickness of the first outer layer 310,
and to meet the USGA requirement that indicates the frontal face
portion has to be all made of the same material.
[0047] The second backing layer 312, as shown in this current
exemplary embodiment of the present invention, may generally be
formed out of a similar first material used to form the first outer
layer 310. Similar material, as referred to in this particular
reference may be other types of titanium such as Ti-811, SP-700,
15-3-3-3, or any .alpha. alloy, any .beta. alloy, or even
.alpha.-.beta. alloys. It should be noted here that once again, the
first material, although generally titanium as discussed above,
could be made out of any other material as well. Moreover, although
the first outer layer 310 and the second backing layer 312 may
generally be made out of a similar titanium material for its high
strength and low density characteristics, they could also be made
out of completely different materials to achieve different goals
and objectives without departing from the scope and content of the
present invention. It should be noted here that the first outer
layer 310 and the second backing layer 312 combine with one another
to form a cavity 313 substantially near a geometric center; adapted
to receive a chip insert 314.
[0048] The cavity 313, as shown in the current exemplary embodiment
of the present invention, may generally have a geometric shape that
is identical to the geometric shape of the chip insert 314 to
ensure proper bonding of all the components. However, cavity 313
need not have the exact same geometry as the chip insert 314, in
fact it can take on other geometric shapes without departing from
the scope and content of the present invention so long as it has
enough interface with the chip insert 314 to ensure a secure bond
between the first outer layer 310, the second backing layer 312,
and itself.
[0049] Chip insert 314, as shown in the current exemplary
embodiment of the present invention, may generally formed out a
second material, which is different from the first material. More
specifically, the second material may generally have a Young's
modulus greater than the Young's modulus of the first material to
allow the central portion of the golf club head to move in and out
of the golf club head 300 as a single unitary entity to improve
performance. Even more specifically, the second material may
generally have a Young's modulus of greater than about 130 GPa,
more preferably greater than about 150 GPa, and most preferably
greater than about 170 GPa. In addition to having a high modulus of
elasticity, the second material may generally have a yield strength
of greater than about 500 MPa, more preferably greater than about
600 MPa, and most preferably greater than about 700 MPa. Finally,
the second material may generally have an ultimate tensile strength
of greater than about 750 MPa, more preferably greater than about
850 MPa, and most preferably greater than about 950 MPa. With the
material properties of the chip insert 314 disclosed above, it can
be seen that there are numerous materials that fit those
characteristics, especially in view of the fact that the first
material could deviate from titanium in some embodiments. However,
in one preferred embodiment of the present invention, the chip
insert 314 may be constructed out of steel for its ease of
availability just as much as for its innate ability to meet the
criteria above. Numerous other materials such as carbon steel,
stainless steel, ceramic, tungsten, plastic, carbide, boron
carbide, metal injection molding materials, or any other material
that fits the description above may all be used without departing
from the scope and content of the present invention so long as it
meets the material properties above.
[0050] FIG. 4 of the accompanying drawing showing an exploded view
of the first outer layer 410, second backing layer 412 having a
cavity 413, and the chip insert 414, provides a clearer
illustration of the relationship between the various components
used to construct this multi-material striking face portion 402.
Despite the relative small number of components involved in the
construction of this multi-material striking face portion 402, the
ability to seamlessly bond the components together requires more
explanation. Although numerous bonding methods such as welding and
brazing could potentially be used to join the components of the
striking face portion 402 together, those methodologies generally
do not provide a sufficiently strong enough bond amongst the
various components to withstand the high impact forces generally
associated with the striking face portion 402 of a golf club
head.
[0051] In order to address the flaws of the traditional bonding
methods, the present invention incorporates numerous advanced
bonding technologies such as diffusion bonding, liquid interface
diffusion, diffusion brazing, or even super plastic forming to name
a few, as these methodologies, amongst others, could be used
achieve the bond strength needed for golf club head
applications.
[0052] In one exemplary embodiment the first outer layer 410, the
second backing layer 412, and the chip insert 414 may be formed
together using diffusion bonding techniques. Diffusion bonding is a
solid state welding process by which two metals can be bonded
together by causing a migration of atoms across the interface by
increasing concentration gradients. Diffusion bonding techniques
generally involve heating up the materials to an elevated
temperature for an extended period of time to allow the materials
to create an extremely strong bond across a large surface. More
details about the diffusion bonding process can be found in U.S.
Pat. No. 7,367,899, the disclosure of which is incorporated by
reference in its entirety.
[0053] As the discussion above has already mentioned, the diffusion
bonding of materials is difficult requiring the heating of the
parts in a very low oxygen atmosphere such as a vacuum or inert gas
under pressure. In order to achieve a sound metallurgical bond, it
is necessary that the two bonding surfaces be very clean and very
flat, allowing the transportation of atoms across the interface to
occur unimpeded. Although it is physically possible to achieve a
surface finish that is sufficiently clean and flat, it is difficult
to achieve such a finish for over a large sized bonding
surface.
[0054] The present invention, in order to improve upon the
drawbacks of the diffusion bonding process, could incorporate an
interlayer without departing from the scope and content of the
present invention. The interlayer may generally be a thin cold
rolled titanium alloy that can be diffusion bonded easily between
two sheets of material that can be difficult to bond via diffusion
bonding over a large surface. The current interlayer may generally
contain materials such as iron, nickel, or cobalt, as the atoms of
these material have high diffusivity with titanium. These elements
are also advantageous because they are beta stabilizers in
titanium, and therefore lowering the beta transition temperatures
of the alloy. In the current invention, the materials used for the
interlayer could be any of the following materials all without
departing from the scope and content of the present invention: ATI
425, SP-700EXHM, Ti-10-2-3, Ti18, Ti54M, Ti-9, or VL-Ti.
[0055] In an alternative embodiment of the present invention, the
components of the striking face portion 402 may be joined together
using liquid interface diffusion techniques. Liquid interface
diffusion bonds eliminates some of the drawbacks of plain diffusion
bonding by utilizing a titanium alloy interface material, an
eutectic material, or a ternary material to lesson the surface
preparation needed. More specifically, because of the existence of
the titanium alloy interface material, liquid interface diffusion
drastically reduces the smoothness, cleanliness, and flatness
requirement of the mating surfaces to ensure proper diffusion
bonding. More details about liquid interface diffusion can be found
in U.S. Pat. No. 3,957,194, the disclosure of which is incorporated
by reference in its entirety.
[0056] In a further alternative embodiment of the present
invention, the components of the striking face portion 402 may be
joined together using super plastic forming. Super plastic forming
is a metalworking process for forming metallic sheets based on the
theory of superelasticity. The super plastic forming process may
generally involve metals having ultra fine grain size being heated
up to promote superelasticity, allowing large and complex
geometries to be created in one operation. More details about super
plastic forming can be found in U.S. Pat. No. 4,603,808, the
disclosure of which is incorporated by reference in its
entirety.
[0057] FIG. 5 of the accompanying drawings shows an enlarged view
of circle C shown in FIG. 3, allowing more details regarding the
striking face portion 502 to be shown. As it can be seen, the
striking face portion 502 has all of the same components such as a
first outer layer 510 having a first thickness d1, a second backing
layer 512 having a second thickness d2, and a chip insert 514
having a third thickness d3. It is worthwhile to mention here that
the measurement of the relative thicknesses d1, d2, and d3 may all
generally be taken at the geometric center of the striking face
portion 502, despite the fact that the FIG. 5 has illustrates the
relative thicknesses at locations that are slightly offset from the
center for ease of illustration. First thickness d1, as shown in
the figures of this current exemplary embodiment may be kept
relatively thin to save unnecessary weight as the front of the face
is in compression during impact. The internal stress caused by the
compression forces experienced by the first outer layer 510 may
generally be smaller than the internal stress caused by the tension
forces experienced by the back of the striking face portion 502,
hence lessening the thickness requirement of thickness d1. More
specifically, first thickness d1 may generally be less than about
0.7 mm, more preferably less than about 0.6 mm, and most preferably
less than about 0.5 mm. Second backing layer 512 having a second
thickness d2, as previously mentioned, is the part of the striking
face portion 502 that is subjected to the highest internal stress
as it comes in tension due to impact with a golf ball; hence
requiring the second thickness d2 to be significantly thicker than
the first thickness d1. More specifically, second thickness d2 may
generally be greater than about 0.8 mm, more preferably thicker
than 0.9 mm, and most preferably thicker than 1.0 mm. Finally,
third thickness d3 shows the thickness of the chip insert 514,
wherein thickness d3 may generally be between about 1.8 mm to about
2.2 mm, more preferably between about 1.9 mm to about 2.1 mm, most
preferably about 2.0 mm.
[0058] Although the relative thicknesses of the various regions of
the striking face portion 502 have all been disclosed above, it is
worthwhile to re-emphasize the importance of the thicknesses with
respect to one another. More specifically, because the second
backing layer 512 is subjected to tension stresses that are
significantly higher than the compressive stresses at the first
outer layer 510, the thickness d2 of the second backing layer 512
needs to be significantly greater than the thickness of the first
outer layer 510. In order to properly capture the thickness
requirements of the various portions of the various components
required for the striking face portion 502 to have sufficient
durability, a "Face Thickness Ratio" is created below in Equation
(1) to capture the relationship between thickness d1 and thickness
d2.
Face Thickness Ratio = Thickness d 1 Thickness d 2 Eq . ( 1 )
##EQU00001##
The striking face portion 502 in accordance with an exemplary
embodiment of the present invention may generally have a "Face
Thickness Ratio" of less than about 0.875, more preferably less
than about 0.66, and most preferably less than about 0.50.
[0059] Chip insert 514 may generally be substantially circular or
oval in shape with a major axis length of about 21.75 mm and a
minor axis of about 11.63 mm. Combined with an approximate
thickness of about 2.0 mm described above, the chip insert 514 may
generally have a volume of about 371.45 mm.sup.3; however minor
deviations in the total volume of the chip insert 514 could occur
while still achieving the same performance gains. More
specifically, chip insert 514 may have a volume of between about
300 mm.sup.3 and about 400 mm.sup.3, or even a volume of between
about 250 mm.sup.3 and 450 mm.sup.3, all without departing from the
scope and content of the present invention. Finally, because it may
generally be undesirable to add excessive weight to the striking
face portion 502 of the golf club head, it is generally desirable
to keep the weight of the chip insert 514 as minimal as possible.
Hence, given some of the material properties discussed above and
the volume ranges above, the chip insert 514 may generally have a
mass of less than 3.0 grams, more preferably less than 2.95 grams,
and most preferably less than 2.90 grams.
[0060] Before moving onto discussions about other embodiments of
the present invention, it is important to point out here that the
chip insert 514 may take on a dome like shape, with the flat side
facing the first outer layer 510 and the rounded side facing the
second backing layer 512. This specific construction eliminates
sharp corners at the rear of the second backing layer 512, which
could be points of elevated stress when subjected to impact forces.
Because the tension stresses at the second backing layer 512 is
significantly higher than the compressive stresses at the first
outer layer 510, it is important to keep the rounded side of the
cavity on the second backing layer 512. The flat side of the dome
interacts with the first outer layer 510 because the compressive
stresses are not as significant, and because this type of dome
cavity construction is easier to create using traditional machining
methods.
[0061] FIG. 6 of the accompanying drawing shows an enlarged
cross-sectional view of a striking face portion 602 in accordance
with an alternative embodiment of the present invention wherein the
chip insert 614 takes on a disk like shape instead of a dome like
shape. Making the chip insert 614 out of a disk like shape instead
of a dome like shape may further improve the performance of the
golf club head by increasing the size of the sweet spot; however
such geometry could make it more difficult to manufacture. More
specifically, FIG. 6 shows the first outer layer 610 having a
plurality of protrusions 616 at the rear of the first outer layer
610 to eliminate any gaps between the components.
[0062] FIG. 7 of the accompanying drawings shows an enlarged
cross-sectional view of a striking face portion 702 in accordance
with an alternative embodiment of the present invention wherein the
chip insert 714 takes on a disk like shape instead of a dome like
shape. However, different from the striking face portion 602 shown
in FIG. 6, striking face portion 702 in this embodiment has a
different parting line allowing the cavity to be formed partially
on the first outer layer 710 and partially on the second backing
layer 712. This type of construction allows the utilization of a
disk shaped chip insert 714 without abnormal shapes on either of
the components.
[0063] FIG. 8 of the accompanying drawings shows a an enlarged
cross-sectional view of a striking face portion 802 in accordance
with an alternative embodiment of the present invention wherein the
chip insert 814 has a corrugated geometry. Having a chip insert 814
with a corrugated construction allows the chip insert 814 to
achieve the high stiffness required all while reducing the overall
weight of the chip insert 814.
[0064] FIG. 9 of the accompanying drawings shows an enlarged
cross-sectional view of a striking face portion 902 in accordance
with an alternative embodiment of the present invention wherein an
extra intermediate layer 916 is sandwiched in between first outer
layer 910 and the second backing layer 912. The incorporation of an
extra intermediate layer 916 significantly simplifies
manufacturing, as both first outer layer 910 and the second backing
layer 912 can now be made out of completely flat surfaces. The only
machining that needs to be done to create a cavity for the chip
insert 914 is in the intermediate layer 916, which can be easily
accomplished without any limitations on the depth of the cavity. In
the current exemplary embodiment of the present invention,
intermediate layer 916 may generally be constructed out of a
similar material as the first outer layer 910 and the second
backing layer 912, however, intermediate layer 916 could be
constructed out of completely different materials without departing
from the scope and content of the present invention so long as it
is capable of being formed together with the other components.
[0065] FIG. 10 of the accompanying drawings shows an enlarged
cross-sectional view of a striking face portion 1002 in accordance
with an alternative embodiment of the present invention wherein it
only has a second backing layer 1012 having a cavity that is filled
in with a chip insert 1014. Notice in this embodiment the striking
face portion 1002 does not have a first outer layer to cover up the
chip insert 1014 to ensure that the outer striking surface is of
uniform material. Although this embodiment may not conform to the
current USGA rules of golf requiring the striking face to be made
out of a uniform material, it could potentially provide significant
performance gains from all other previously mentioned embodiments
that add unnecessary weight to the frontal surface of the striking
face portion 1002. As mentioned before, because the stresses at the
frontal portion is so minimal, it is not necessary to reinforce the
frontal portion, thus allowing the chip insert 1014 to be exposed.
In a slightly different embodiment than what is shown in FIG. 10,
the frontal portion of the striking face portion 1002 could be
covered with a thin film of titanium or any other material to
achieve the weight savings of the embodiment shown in FIG. 10 all
while visually conforming to the USGA requirements.
[0066] FIG. 11 of the accompanying drawings shows an exploded view
of a striking face portion 1102 in accordance with an alternative
embodiment of the present invention. More specifically, in this
alternative embodiment of the present invention the first outer
layer 1110 may not need to occupy the entire frontal surface to
achieve the same objectives. Although this embodiment shown in FIG.
11 may require more machining work in terms of machining out an
outer pocket 1115 in addition to the cavity 1113, it significantly
reduces the bonding surface between the components. The reduction
of the bonding surface may be desirable in situations that involve
diffusion bonding or liquid interface diffusion processes are used,
as both of these processes require significant surface preparation
to achieve a bond. The first outer layer 1110 in this current
exemplary embodiment may take on the shape of a circular disk in
order to provide a shape that is easier to machine, however, as it
will be shown in more detail later, first outer layer 1110 may take
on any shape that is smaller than the outer perimeter of the
striking face portion 1102 without departing from the scope and
content of the present invention. Finally, it is worth to note here
that the first outer layer 1110 may generally be made out of the
same titanium material as the second backing layer 1112 allowing
the end product to have a uniform striking surface in conformity
with the USGA rules. However, the first outer layer 1110 may be
formed out of a substantially similar, or even completely different
material than the second backing layer 1112 without departing from
the scope and content of the present invention.
[0067] FIG. 12 of the accompanying drawings shows an exploded view
of a striking face portion 1202 in accordance with an alternative
embodiment of the present invention. More specifically, the first
outer layer 1210 may have a shape that significantly resembles the
shape of the chip insert 1214, but large enough to cover the chip
insert 1214 itself. Correspondingly, the outer pocket 1215 may also
take on the similar shape of the first outer layer 1210 without
departing from the scope and content of the present invention.
Having the first outer layer 1210 take on a shape that is similar
to the shape of the chip insert 1214 may provide a more focused
shape for the first outer layer 1210, further reducing the amount
of surface preparation needed for the diffusion bonding of the
various components.
[0068] FIG. 13 of the accompanying drawings shows an enlarged
cross-sectional view of the embodiments of the present invention
wherein the first outer layer 1310 may not cover up the entire
frontal striking surface of the golf club head. More specifically,
as the cross-sectional image of FIG. 13 shows, the first outer
layer 1310 may only partially cover the frontal striking surface.
The cross-sectional view of this embodiment also shows that the
bonding surfaces between the components to be significantly
reduced, to minimize the surface preparation needed for diffusion
bonding techniques.
[0069] In an alternative embodiment of the present invention, two
or more inserts can be used around the central perimeter portion of
the striking face to create a completely different effect of
increasing the coefficient of restitution instead of increasing the
size of the sweet spot as described above. FIG. 14 of the
accompanying drawings shows an enlarged exploded view of a face
insert 1406 in accordance with this alternative embodiment of the
present invention containing a first outer layer 1410, an upper
insert 1420 corresponding to an upper cavity 1421, a lower insert
1422 corresponding to a lower cavity 1423, and a backing plate 1424
located at a rear portion of the face insert 1406 corresponding to
a rear cavity 1425. This specific relationship between the various
components creates a relationship wherein the backing layer is
adapted to directly contact the first outer layer, the upper
insert, and the lower insert, simultaneously.
[0070] In this alternative embodiment of the present invention,
similar to the prior embodiments, the upper and lower inserts 1420
and 1422 respectively are made out of a material of a relative high
Young's modulus, especially when compared to the material used to
form the first outer layer 1410 of the face insert 1406. When these
inserts are placed away from the geometric center of the face
insert 1406, they no longer serve the purpose of increasing the
size of the sweet spot. Instead, the incorporation of the inserts
away from the geometric center of the face insert 1406 now serve
the purpose of increasing the overall coefficient of restitution of
the face insert 1406 by creating an ultra-thin and compliant
portion near the geometric center, while using the upper and lower
inserts 1420 and 1422 to expand that area of high compliance while
maintaining the durability requirements by providing some sort of
support.
[0071] The relative thickness' of the various portions of the face
insert 1406 is important to the proper functionality of the current
invention. In order to properly illustrate the relative thickness
of the various components of the face insert 1406, a
cross-sectional view of the face insert 1406 is provided in FIG.
15. FIG. 15 of the accompanying drawings provides a cross-sectional
view of a face insert 1506 of a golf club head in accordance with
an alternative embodiment of the present invention incorporating
two or more inserts away from a geometric center of the face insert
1506.
[0072] The first outer layer 1510 may generally be made out of a Ti
15-3-3-3 material with a thickness d4 of about 1.0 mm at its
thinnest area and a thickness d6 of about 2.7 mm at its thickest
area. More specifically, thickness d4 may generally be between
about 0.75 mm to about 1.25 mm, more preferably between about 0.85
mm to about 1.15 mm, and most preferably about 1.0 mm; while
thickness d6 may generally be greater than about 2.50 mm, more
preferably greater than about 2.60 mm, most preferably greater than
about 2.70 mm all without departing from the scope and content of
the present invention. The first material used to form the first
outer layer 1510 may generally have a low Young's modulus to
generate more flexural stiffness that could create more ballspeed.
In fact, the Young's modulus of the first material is preferably
less than about 100 GPa, more preferably less than about 90 GPa,
and most preferably less than about 85 GPa.
[0073] The upper insert 1520 and the lower insert 1522, as shown in
this exemplary embodiment, may generally be comprised out of the
same material having the same thickness. More specifically, the
upper and lower inserts 1520 and 1522 may generally be comprised
out of a Ti-6-4 material that may have a thickness d5 and d7 of
about 1.2 mm in order to adjust the difference in the stress points
across the different regions of the face. However, the thickness d5
and d7 of the upper and lower inserts 1520 and 1522 may differ
slightly from the 1.2 mm number mentioned above in the ranges of
between about 1.0 mm to about 1.4 mm, and more preferably between
about 1.1 mm to about 1.3 mm all without departing from the scope
and content of the present invention. Generally speaking, the
Young's modulus of a second material used to form the upper insert
1520 and the lower insert 1522 may generally have a higher Young's
modulus than the first material. More specifically, the Young's
modulus of the second material may generally be greater than about
125 GPa, more preferably greater than about 130 GPa, and most
preferably greater than about 135 GPa.
[0074] It should be noted here that although in this preferred
embodiment of the present invention the upper insert 1520 and the
lower insert 1522 are generally made of the same material having
the same thickness, the materials and the thickness' could differ
from one another to achieve a different objective without departing
from the scope and content of the present invention. Because the
face insert 1506 of a golf club head experiences higher stress
levels near the crown portion, and less stress levels near the sole
portion, the material of the upper and lower inserts 1520 and 1522
respectively could be adjusted to further enhance the performance.
In one alternative embodiment, the upper insert 1520 could be made
out of a second material that is a Ti-6-4 material described above,
while the lower insert may be constructed out of a third material
that is a Ti 15-5-3 material having a Young's modulus of about 75
GPa. Despite the fact that the third material has a lower Young's
modulus than the second material, it still has a higher Young's
modulus than the first material in this embodiment.
[0075] The backing plate 1524, as shown in this exemplary
embodiment, may generally be comprised out of a high strength
titanium such as Ti-8-1-1 to create structural support for the face
insert itself. The thickness d8 of the backing plate 1524 may
generally be less than about 0.70 mm, more preferably less than
about 0.60 mm, and most preferably less than about 0.50 mm, all
without departing from the scope and content of the present
invention. This fourth material may generally be a Ti-8-1-1
material having a Young's modulus of between about 115 GPa and
about 130 GPa, more preferably between about 118 GPa and about 127
GPa, and most preferably about 125 GPA all without departing from
the scope and content of the present invention.
[0076] FIG. 16 of the accompanying drawings shows a cross-sectional
view of a golf club head incorporating a face insert 1606 with the
multiple materials inserts located away from the geometric center
of the face insert 1606. This cross-sectional view of the golf club
head illustrates how the face insert 1606 engages the body portion
1604 of the golf club head in terms of their relative thickness. In
fact, in this current exemplary embodiment of the present
invention, the transition zone 1632 between the face insert 1606
and the body portion 1604 is kept at the same consistent thickness
of d6 as previously described in FIG. 15 of the accompanying
drawings. This consistency in maintaining the thickness of the face
insert 1606 and the body portion 1604 near the junction promotes
more consistency in the stress levels across the transition to
ensure more face compliance to increase the coefficient of
restitution.
[0077] FIG. 17 of the accompanying drawings shows a cross-sectional
view of a golf club head in accordance with a further alternative
embodiment of the present invention. More specifically, the golf
club head shown in FIG. 17 illustrates a transition zone 1732 that
has a difference in thickness from the face insert 1706 portion to
the body portion 1704. Even more specifically, the thickness of the
face insert 1706 in this embodiment may generally be thicker than
the remainder of the body portion 1704 to achieve greater strength
and durability. This difference in thickness between the two
components will generally result in a stair stepped transition zone
1732 both at the top and bottom of the face insert 1706.
[0078] FIG. 18 of the accompanying drawings shows an exploded view
of a face insert 1806 in accordance with a further alternative
embodiment of the present invention containing a first outer layer
1810 corresponding to an outer cavity 1825, an upper insert 1820
corresponding to an upper cavity 1821, a lower insert 1822
corresponding to a lower cavity 1823, and a backing body 1824
located at a rear portion of the face insert 1806 forming the outer
cavity 1825, the upper cavity 1821, and the lower cavity 1823. This
embodiment differs from the face insert 1406 shown in FIG. 14 by
reversing the orientation of the first outer layer 1810, the upper
insert 1820, the lower insert 1822, and the backing body 1824. In
this alternative embodiment, the first outer layer 1810 is in the
shape of a plate at the frontal portion of the face insert 1806,
while the upper and lower inserts 1820 and 1822 respectively are
placed just behind the first outer layer 1810. Finally, the backing
body 1824, which contains the upper cavity 1821, the lower cavity
1823, and the frontal cavity 1825, is placed at the rear portion of
the face insert 1806.
[0079] The alternative embodiment of the present invention shown in
FIG. 18 may be preferred over the reverse orientation shown in FIG.
14 in situations where the bond between the layer can be difficult
to achieve via the bonding processes described above. In these
situations, it might be beneficial to reverse the orientation and
placement of the components to have the loose components be placed
on the compression side of a golf ball impact with the striking
face instead of the tension side of a golf ball impact with the
striking face. Having the loose components be installed on the
frontal compression side of the striking face will prevent these
components such as the first outer layer 1810, the upper insert
1820 and the lower insert 1822 from coming apart from one another
as the compressive forces will strengthen the bond of the
components; whereas the tension forces will weaken the bond of the
components if installed at the rear portion.
[0080] FIG. 19 of the accompanying drawings shows a cross-sectional
view of a golf club head incorporating the face insert 1906 with
multiple material inserts as described in the previous embodiment
in FIG. 18. In this embodiment of the present invention, it can be
seen that the first outer layer 1910 is located at the outer
surface of the face insert 1906 with an upper and lower insert 1920
and 1922 located right behind it. All three of the components are
then assembled to a backing body 1924 having corresponding cavities
for the aforementioned components to create the face insert
1906.
[0081] FIGS. 20-26 show alternative embodiments of the present
invention wherein the similar materials with different properties
can be joined together to improve the performance of the golf club
head. In these embodiments, the joining of similar materials with
slightly different properties may be preferential to earlier
embodiments where the bonding process involves two completely
different materials; as similar materials are easier to bond to one
another using the processes discussed above. In the following
embodiments, the two similar materials may be two different types
of titanium materials having different Young's modulus such as
Ti-8-1-1-1 and Ti 6-4; however different types of materials may be
used without departing from the scope and content of the present
invention as long as they have a different Young's modulus.
[0082] Although the specific embodiments in FIGS. 20-26 may utilize
different geometric assemblies of the material, all of the
geometries derive from the analysis of the impact forces occurring
during contact with a golf ball. For example, a material with a
higher Young's modulus may be used at locations where the striking
face will experience higher stress levels; while a material with a
lower Young's modulus may be used at locations where the striking
face will experience lower stress levels. Higher Young's modulus
titanium materials may be any of Ti 8-1-1-1, Ti 15-3-3-3, Ti
15-5-3, SP700 or SP700HM with a Young's modulus of greater than
about 110 GP, more preferably greater than about 115 GPa, and most
preferably greater than about 120 GPa, to name a few. On the other
hand, the lower Young's modulus titanium materials may be any of Ti
6-4, Ti 3-2.5, Ti 3-1-1-1, or Ti 5-1-1-1 with a Young's modulus of
less than about 110 GPa more preferably less than about 105 GPa,
and most preferably less than about 100 GPa, to name a few.
[0083] Moving on the actual figures, FIG. 20 shows a perspective
view of a golf club head 2000 with two dissimilar types of titanium
materials 2052 and 2054 forming the face insert 2006. In this
embodiment, the first titanium material 2052 may be a titanium
material with a lower Young's modulus while the second titanium
material 2054 may be a titanium material with a higher Young's
modulus. Alternatively speaking, it can be said that the second
titanium material 2054 may have a higher Young's modulus than the
first titanium material 2052.
[0084] FIG. 21 of the accompanying drawings also shows a
perspective view of a golf club head 2100, with the dissimilar
titanium materials 2152 and 2154 having a different geometric
composition to create the face insert 2106. Similar to the
discussion above, the first titanium material 2152 may generally be
a titanium material with a lower Young's modulus while the second
titanium material 2154 may be a titanium material with a higher
Young's modulus.
[0085] FIGS. 22-26 all share the similar concept as FIGS. 20-21
discussed above, and merely show different geometric shapes used
for the first titanium material 2252, 2352, 2452, 2552, and 2652
with a lower Young's modulus as well as for the second titanium
material 2254, 2354, 2454, 2554, and 2654 with a higher Young's
modulus. The different geometries shown in the different
embodiments in FIG. 22-26 may look significantly different on its
face, but all of the specific geometries are based on strengthening
the high stress regions of the striking face with a titanium
material having higher Young's modulus.
[0086] Other than in the operating example, or unless otherwise
expressly specified, all of the numerical ranges, amounts, values
and percentages such as those for amounts of materials, moment of
inertias, center of gravity locations, loft, draft angles, various
performance ratios, and others in the aforementioned portions of
the specification may be read as if prefaced by the word "about"
even though the term "about" may not expressly appear in the value,
amount, or range. Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the following specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques.
[0087] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting form the
standard deviation found in their respective testing measurements.
Furthermore, when numerical ranges of varying scope are set forth
herein, it is contemplated that any combination of these values
inclusive of the recited values may be used.
[0088] It should be understood, of course, that the foregoing
relates to exemplary embodiments of the present invention and that
modifications may be made without departing from the spirit and
scope of the invention as set forth in the following claims.
* * * * *