U.S. patent application number 13/842011 was filed with the patent office on 2013-08-29 for golf club heads with improved sound characteristics.
This patent application is currently assigned to Taylor Made Golf Company, Inc.. The applicant listed for this patent is Taylor Made Golf Company, Inc.. Invention is credited to Todd P. Beach, Bing-Ling Chao, Brandon H. Woolley.
Application Number | 20130225320 13/842011 |
Document ID | / |
Family ID | 49003480 |
Filed Date | 2013-08-29 |
United States Patent
Application |
20130225320 |
Kind Code |
A1 |
Woolley; Brandon H. ; et
al. |
August 29, 2013 |
GOLF CLUB HEADS WITH IMPROVED SOUND CHARACTERISTICS
Abstract
Golf club heads with improved sound can be provided while
implementing an adjustable loft, lie, and face angle adjustment
system. A face portion is attached to the front portion of the golf
club head. A sleeve is received in the hosel portion having a
sleeve bore, a threaded portion, and an anti-rotation portion. A
screw inserted into a sole opening in the sole portion configured
to engage the threaded portion of the sleeve.
Inventors: |
Woolley; Brandon H.; (Vista,
CA) ; Chao; Bing-Ling; (San Diego, CA) ;
Beach; Todd P.; (Encinitas, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taylor Made Golf Company, Inc.; |
|
|
US |
|
|
Assignee: |
Taylor Made Golf Company,
Inc.
Carlsbad
CA
|
Family ID: |
49003480 |
Appl. No.: |
13/842011 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13331798 |
Dec 20, 2011 |
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13842011 |
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61428547 |
Dec 30, 2010 |
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Current U.S.
Class: |
473/342 ;
473/324; 473/345; 473/347 |
Current CPC
Class: |
A63B 53/047 20130101;
A63B 53/0433 20200801; A63B 60/00 20151001; A63B 53/0408 20200801;
A63B 53/0462 20200801; A63B 53/0466 20130101; A63B 2209/00
20130101; A63B 2209/02 20130101; A63B 53/042 20200801; A63B 53/0425
20200801 |
Class at
Publication: |
473/342 ;
473/324; 473/345; 473/347 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Claims
1. A golf club comprising: a golf club head with a body having a
front portion, a crown portion, a sole portion, and a hosel
portion, the body comprised of a first material; a hosel bore
located in the hosel portion; a sleeve having a sleeve bore, a
threaded portion, and an anti-rotation portion, the sleeve being
configured to be received in the hosel portion; a screw configured
to engage the threaded portion of the sleeve, the screw also
configured to be inserted into a sole opening in the sole portion;
a first longitudinal axis defined by the sleeve bore; a second
longitudinal axis defined by the hosel bore of the hosel portion;
an offset angle located between the first longitudinal axis and
second longitudinal axis, the offset angle being between 0 degrees
and 4 degrees; a face portion comprising a second material and
being configured to be attached to the front portion of the body,
the face portion having a face size surface area being at least at
least 4,500 mm.sup.2; a coefficient of restitution greater than
0.79 and a characteristic time greater than 220 .mu.s; a loudness
of the club head is less than 240 sones upon striking a golf ball
at about 110 mph, measured by a microphone positioned at 64 inches
above the golf ball, wherein the face portion has a characteristic
time slope of greater than 10 and less than 150.
2. The golf club of claim 1, wherein the second material is a
composite material having a layup-to-fiber ratio of greater than
0.5 but less than 1.
3. The golf club of claim 1, wherein the second material is a
composite material having a strength-to-modulus fiber ratio of
greater than 1 and less than 10.
4. The golf club of claim 3, wherein the second material includes a
strength-to-modulus layup ratio of greater than 0.5 and less than
10.
5. The golf club of claim 1, wherein the face portion further
includes a face insert; a recess that receives the face insert and
defines a face insert depth; a rear support member having an end
point thickness; and a face insert ratio between 0.5 and 10, the
face insert ratio being defined as the face insert depth divided by
the end point thickness.
6. The golf club of claim 1, wherein a peak un-weighted acoustic
amplitude of the club head is less than 114 dB, a peak A-weighted
sound pressure level of the club head is less than 5 Pa as measured
by the microphone positioned at 64 inches above the golf ball.
7. The golf club of claim 1, wherein the face portion includes a
face insert having a face insert area and a face insert
area-to-face size ratio of greater than 0.65 and less than 1.
8. The golf club of claim 7, wherein the golf club head further
includes a maximum sound power-to-frequency ratio greater than
1*10.sup.-5 watts/hertz and less than 4.5*10.sup.-5
watts/hertz.
9. The golf club of claim 1, wherein the golf club has a head
volume between 400 cc to about 475 cc.
10. The golf club of claim 8, wherein the golf club head has a
frequency-to-volume ratio of greater than 6.0 hertz/cc and less
than 16 hertz/cc.
11. The golf club of claim 1, wherein the golf club head includes
frequency-to-offset angle ratio between 1,000 Hz/degree to 7,000
Hz/degree.
12. The golf club of claim 1, wherein the sole opening is located
adjacent to a non-undercut portion.
13. The golf club of claim 12, wherein a heel-side rear support
member is integral with an internal hosel tube structure.
14. A golf club comprising: a golf club head with a body having a
front portion, a crown portion, a sole portion, and a hosel
portion, the body comprised of a first material; a face portion
comprising a second material and being configured to be attached to
the front portion of the body; a sleeve having a sleeve bore, a
threaded portion, and an anti-rotation portion, the sleeve being
configured to be received in the hosel portion; a screw configured
to engage the threaded portion of the sleeve, the screw also
configured to be inserted into a sole opening in the sole portion;
a first longitudinal axis defined by the sleeve bore; a second
longitudinal axis defined by a hosel bore of the hosel portion; an
offset angle located between the first longitudinal axis and second
longitudinal axis, the offset angle being between 0 degrees and 4
degrees; a peak un-weighted acoustic amplitude of the club head is
less than 113 dB upon striking a golf ball at about 110 mph,
measured by a microphone positioned at 64 inches above the golf
ball, wherein the face portion has a characteristic time slope of
greater than 10 and less than 150.
15. The golf club of claim 14, wherein the second material is a
composite material having a layup-to-fiber ratio of greater than
0.5 but less than 1.
16. The golf club of claim 14, wherein the second material is a
composite material having a strength-to-modulus fiber ratio of
greater than 1 and less than 10.
17. The golf club of claim 14, wherein the second material is a
composite material having a strength-to-modulus layup ratio of
greater than 0.5 and less than 10.
18. A golf club comprising: a golf club head with a body having a
front portion, a crown portion, a sole portion, and a hosel
portion, the body comprised of a first material; a face portion
comprising a second material and being configured to be attached to
the front portion of the body; a sleeve having a sleeve bore, a
threaded portion, and an anti-rotation portion, the sleeve being
configured to be received in the hosel portion; a screw configured
to engage the threaded portion of the sleeve, the screw also
configured to be inserted into a sole opening in the sole portion;
a first longitudinal axis defined by the sleeve bore; a second
longitudinal axis defined by a hosel bore of the hosel portion; an
offset angle located between the first longitudinal axis and second
longitudinal axis, the offset angle being between 0 degrees and 4
degrees; a peak A-weighted sound pressure level of the club head is
less than 5 Pa upon striking a golf ball at about 110 mph, measured
by a microphone positioned at 64 inches above the golf ball,
wherein the face portion has a characteristic time slope of greater
than 10 and less than 150.
19. The golf club of claim 18, wherein the second material is a
composite material having a strength-to-modulus layup ratio of
greater than 0.5 and less than 10.
20. The golf club of claim 18, wherein the second material is a
composite material having a layup-to-fiber ratio of greater than
0.5 but less than 1.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/428,547 and is a continuation-in-part of U.S.
patent application Ser. No. 13/331,798, which is incorporated
herein by reference in its entirety.
[0002] The following disclosure is provided with reference to U.S.
patent application Ser. Nos. 11/960,609 11/642,310, 11/825,138,
11/998,436, 11/823,638, 12/004,386, 12,004,387, 11/960,610,
12/156,947, 12/462,198, 11/895,195 and U.S. Pat. Nos. 6,800,038,
6,824,475, 6,904,663, 6,997,820, 7,140,974, 6,811,496, 7,267,620
and 7,066,832 which are incorporated herein by reference in their
entirety.
BACKGROUND
[0003] Golf clubs, especially wood type golf clubs such as driver,
fairway woods, and hybrids can provide large "sweet spots" to
reduce the ill effects of mishits. In addition, golf club makers
provide such clubs with mass distributions that can tend to promote
particular ball trajectories, and have preferred club head moments
of inertia. Mass distribution in some such clubs can be readily
adjusted by a golfer to promote a selected shot properties such as
a fade or draw to compensate for individual swing
characteristics.
[0004] Driver type golf clubs with large heads can provide golfers
with enhanced confidence when they approach a shot. However, club
manufactures have not recognized and addressed how club head sounds
relate to golfer playing experience. Some large driver type club
heads produce loud and unpleasant sounds when used to strike a
ball. Some golf equipment reviewers have suggested that in some
cases, a particular driver should come with earplugs. Thus, golf
clubs, especially driver type golf clubs are needed that can
provide superior sound characteristics.
SUMMARY
[0005] Methods comprise selecting a striking face material for a
golf club head, and selecting a striking face area and thickness. A
striking face acoustic mode frequency is determined, and based on
the determined frequency, the striking face is adjusted. In some
examples, the striking face is adjusted by varying a thickness or
selecting a material having a different elastic constant or
density. Typically, the club face is adjusted so that a lowest
resonance frequency of the club face is greater than about 3.8 kHz,
4.0 kHz, 4.2 kHz, or 4.5 kHz. In other examples a sole acoustic
mode or a crown acoustic mode at a frequency less than about 3.5
kHz is identified, and the sole or crown is adjusted so as to
reduce an amplitude of the sole or crown acoustic mode when
striking a golf ball. In some embodiments, a sole acoustic mode or
a crown acoustic mode at a frequency less than about 2.5 kHz or 2.0
kHz is identified. In other examples, an A-weighted sound pressure
or a sound level in response to a ball strike is determined. If the
sound pressure or sound level exceeds a limit associated with a
satisfactory sound, the club head is adjusted. In some examples,
the limit is 225 sones or an A-weighted sound pressure of 5 Pa in
response to a golf ball strike at a club head speed of about 110
mph. (As used herein, A-weighted sound pressures are at a distance
of about 1 m). The "golf ball" used in all tests described herein
is a TaylorMade.RTM. Tour Preferred.RTM. TP Red golf ball.
[0006] Driver type golf club heads include a club body configured
to receive a striking plate and a composite striking plate
configured to have a lowest order acoustic resonance frequency at a
frequency of at least 3.8 kHz.
[0007] In one aspect of the invention, a golf club head is
described having a body having a front portion, a crown portion, a
sole portion, and a hosel portion. The body is comprised of a first
material and a hosel bore is located in the hosel portion. A sleeve
having a sleeve bore, a threaded portion, and an anti-rotation
portion is received in the hosel portion. A screw engages the
threaded portion of the sleeve. The screw is inserted into a sole
opening in the sole portion. A first longitudinal axis is defined
by the sleeve bore and a second longitudinal axis is defined by the
hosel bore of the hosel portion. An offset angle is located between
the first longitudinal axis and second longitudinal axis. The
offset angle is between 0 degrees and 4 degrees. A face portion
comprising a second material is attached to the front portion of
the body, the face portion having a face size surface area being at
least at least 4,500 mm.sup.2. A coefficient of restitution greater
than 0.79 and a characteristic time greater than 220 .mu.s is also
disclosed. A loudness of the club head is less than 240 sones upon
striking a golf ball at about 110 mph. The loudness is measured by
a microphone positioned at 64 inches above the golf ball. The face
portion has a characteristic time slope of greater than 10 and less
than 150.
[0008] In another aspect of the invention, the second material is a
composite material having a layup-to-fiber ratio of greater than
0.5 but less than 1.
[0009] In yet another aspect of the invention, the second material
is a composite material having a strength-to-modulus fiber ratio of
greater than 1 and less than 10. In addition, the second material
is a composite material having a strength-to-modulus layup ratio of
greater than 0.5 and less than 10.
[0010] In another aspect of the invention, the face portion
includes a face insert and a recess that receives the face insert
and defines a face insert depth. A rear support member is disclosed
having an end point thickness. A face insert ratio between 0.5 and
10 is also disclosed. The face insert ratio is defined as the face
insert depth divided by the end point thickness.
[0011] In yet another aspect of the invention, a peak un-weighted
acoustic amplitude of the club head is less than 114 dB. A peak
A-weighted sound pressure level of the club head is less than 5 Pa
as measured by the microphone positioned at 64 inches above the
golf ball. The face portion includes a face insert having a face
insert area and a face insert area-to-face size ratio of greater
than 0.65 and less than 1.
[0012] In one aspect of the invention, the golf club head further
includes a maximum sound power-to-frequency ratio greater than
1*10.sup.-5 watts/hertz and less than 4.5*10.sup.-5 watts/hertz.
The golf club has a head volume between 400 cc to about 475 cc and
has a frequency-to-volume ratio of greater than 6.0 hertz/cc and
less than 16 hertz/cc. The golf club head includes at least one
movable weight.
[0013] In another aspect of the invention, the sole opening is
located adjacent to a non-undercut portion. Furthermore, a
heel-side rear support member is integral with an internal hosel
tube structure.
[0014] Methods comprise determining an acoustic resonance frequency
of a driver type golf club head sole, crown, or face, and
evaluating the resonance frequency to determine if a club head is
to be adjusted. Based on the evaluation, at least one of the
following adjustments is performed: selecting a less dense material
for a crown, sole, or face; altering a face thickness, thinning or
thickening a club face at an antinode of the acoustic resonance. In
some examples, an acoustic level associated with a club face/golf
ball impact is determined, and the club head is adjusted based on
the determination.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is an exploded view of a club head in accordance with
the invention, depicting a composite face insert and a metallic
body.
[0016] FIG. 2 is a cross-sectional view of the club head of FIG.
1.
[0017] FIG. 3 is an exploded view of the composite region of the
face insert of FIG. 1 showing the plies comprising the composite
region.
[0018] FIG. 4 is a close-up view of area A-A of the club head of
FIG. 2, depicting a junction of the composite face insert and the
body portion.
[0019] FIG. 5 is a graph depicting resin viscosity over time during
the soaking and curing phases for a preferred method of forming the
composite portion of the face insert of FIG. 1.
[0020] FIG. 6 is a graph depicting pressure over time during the
soaking and curing phases of forming the composite portion of the
face insert, corresponding to FIG. 5.
[0021] FIG. 7 is a graph depicting temperature over time during the
soaking and curing phases of forming the composite portion of the
insert, corresponding to FIG. 5.
[0022] FIG. 8 is a graph depicting pressure over time during the
soaking and curing phases of an alternative method of forming the
composite portion of the insert of FIG. 1.
[0023] FIG. 9 is a graph depicting temperature over time during the
soaking and curing phases of forming the composite portion of the
insert, corresponding to FIG. 8.
[0024] FIG. 10A illustrates a front view of an embodiment of a golf
club head in an address position.
[0025] FIG. 10B illustrates a toe-side view of the golf club head
shown in FIG. 10A.
[0026] FIG. 11 illustrates a cross-sectional side view of a golf
club head taken through an ideal impact location, according to one
embodiment.
[0027] FIG. 12 illustrates a cross-sectional side view of a golf
club head taken through an ideal impact location, according to
another embodiment.
[0028] FIG. 13A illustrates a cross-sectional side view of a golf
club head taken through an ideal impact location, according to
another embodiment.
[0029] FIG. 13B illustrates a detailed view of a lower leading edge
zone.
[0030] FIG. 14A illustrates an adhesive interface between a face
insert and club head body, according to one embodiment.
[0031] FIG. 14B illustrates an adhesive interface between a face
insert and club head body, according to another embodiment.
[0032] FIG. 15A illustrates an engineering gap between a face
insert and a club head body, according to another embodiment.
[0033] FIG. 15B illustrates a front view of the golf club head
shown in FIG. 15A.
[0034] FIG. 16 illustrates a cross-sectional side view of a golf
club head taken through an ideal impact location, according to
another embodiment.
[0035] FIG. 17 illustrates a cross-sectional side view of a golf
club head taken through an ideal impact location, according to
another embodiment.
[0036] FIG. 18 illustrates a cross-sectional side view of a golf
club head taken through an ideal impact location, according to
another embodiment.
[0037] FIG. 19 illustrates a front view of a golf club head in an
address position, according to another embodiment.
[0038] FIG. 20 is a representative method of evaluating and
modifying golf club head acoustic characteristics.
[0039] FIG. 21A is a graph illustrating acoustic vibrational
amplitude as a function of time and frequency subsequent to
striking a golf ball for a representative club head (#2) having a
composite striking plate.
[0040] FIG. 21B illustrates acoustic vibrational amplitude at a
frequency of about 3.84 kHz that is associated with a striking
plate acoustic mode. (Club head #2).
[0041] FIG. 22A is a graph illustrating acoustic vibrational
amplitude as a function of time and frequency subsequent to
striking a golf ball for a representative club head (#1) having a
titanium alloy striking plate.
[0042] FIGS. 22B-22E provide additional data for club head #1. FIG.
22B illustrates acoustic vibrational amplitude at a frequency of
about 3.13 kHz that is associated with a striking plate acoustic
mode for the club head used to obtain the data of FIG. 22A.
[0043] FIG. 22C illustrates relative acoustic amplitude as a
function of frequency when this club head is used by two players
(referred to herein for convenience as "Player A" and "Player B")
to strike a golf ball with different swing speeds.
[0044] FIGS. 22D-22E are graphs illustrating loudness (sones) and
acoustic amplitude (dB) as a function of time for the two different
players.
[0045] FIG. 23A is a graph illustrating acoustic vibrational
amplitude as a function of time and frequency subsequent to
striking a golf ball for a representative club head (#3) having a
composite striking plate with a titanium cap.
[0046] FIGS. 23B-23D provide additional data for club head #3. FIG.
23B illustrates relative acoustic amplitude as a function of
frequency associated with a club head having a Ti-capped composite
striking surface for ball strikes by two players with different
swing speeds.
[0047] FIGS. 23C-23D are graphs illustrating loudness (sones) and
acoustic amplitude (dB) as a function of time for ball strikes the
two different players with the Ti-capped composite striking
face.
[0048] FIG. 24A is a graph illustrating acoustic vibrational
amplitude as a function of time and frequency subsequent to
striking a golf ball for a representative club head (#4) having a
titanium striking plate.
[0049] FIGS. 24B-24G provide additional data for club head #4.
FIGS. 24B-24D illustrate acoustic vibrational amplitude at
frequencies of about 1.84 kHz, 2.59 kHz, and 3.93 kHz,
respectively, that are associated with a sole mode, a crown mode,
and a striking plate mode, respectively.
[0050] FIG. 24E illustrates relative acoustic amplitude as a
function of frequency associated with the club head used for FIG.
24A for ball strikes by two players with different swing
speeds.
[0051] FIGS. 24F-24G are graphs illustrating loudness (sones) and
acoustic amplitude (dB) as a function of time for ball strikes by
the two different players.
[0052] FIGS. 25A-25D are graphs illustrating acoustic vibrational
amplitude as a function of time and frequency subsequent to
striking a golf ball for a representative club head (#5) having a
composite striking plate. FIG. 25B illustrates relative acoustic
amplitude as a function of frequency associated with ball strikes
by two players with different swing speeds. FIGS. 25C-25D are
graphs illustrating loudness (sones) and acoustic amplitude (dB) as
a function of time for the two different players.
[0053] FIGS. 26-27 are graphs illustrating acoustic vibrational
amplitude as a function of time and frequency subsequent to
striking a golf ball for additional representative club heads (#6
and #7, respectively) having a composite striking plate.
[0054] FIGS. 28A-28B illustrate sound levels in sones and an
A-weighted sound pressure, respectively, for a plurality of club
heads, in response to ball strikes with a club head speed of about
110 mph.
[0055] FIG. 29 illustrates a chart comparing loudness and face
size.
[0056] FIG. 30 illustrates a chart comparing face frequency and
face size.
[0057] FIG. 31 illustrates a chart comparing peak un-weighted
signal and face size.
[0058] FIG. 32 illustrates a chart comparing peak un-weighted
signal and face frequency.
[0059] FIG. 33A illustrates a method of measuring face size.
[0060] FIG. 33B illustrates a method of measuring face size to
exclude the hosel portion surface area.
[0061] FIG. 33C illustrates a face surface area projected onto a
plane.
[0062] FIG. 34A illustrates a top view of a golf club head.
[0063] FIG. 34B is an elevated front view of the golf club head in
FIG. 34A showing a golf club head origin coordinate system and a
center of gravity according to one embodiment.
[0064] FIG. 34C is an elevated toe view of the golf club head in
FIG. 34A.
[0065] FIG. 34D is an isometric sole view of the golf club head in
FIG. 34A.
[0066] FIG. 34E is a cross-sectional view taken along section lines
34E-34E in FIG. 34B.
[0067] FIG. 35 is a cross-sectional view of an undercut and
non-undercut structure taken along section lines 35-35 in FIG.
34A.
[0068] FIG. 36A illustrates an acoustic amplitude as a function of
frequency associated with the club head described in FIGS. 34A-E
and FIG. 35 for two different swing speeds.
[0069] FIG. 36B illustrates loudness (sones) as a function of time
for the two different players.
[0070] FIG. 36C illustrates acoustic amplitude (dB) as function of
time for the two different players.
[0071] FIG. 37 illustrates a detailed cross-sectional view of an
undercut region.
[0072] FIG. 38 illustrates a sound power estimate of an exemplary
embodiment.
[0073] FIG. 39 illustrates a sound power estimate of another
exemplary embodiment.
[0074] FIG. 40 illustrates a characteristic time slope.
DETAILED DESCRIPTION
[0075] With reference to the illustrative drawings, and
particularly FIGS. 1 and 2, there is shown a golf club head 10
having a metallic body 12 and a face insert 14 comprising a
composite region 16 and a metallic cap 18. The face insert 14 is
durable and yet lightweight. As a result, weight can be allocated
to other areas of the club head 10, enabling the club head's center
of gravity to be desirably located farther from the striking face
40 and to further enhance the club head's moment of inertia. The
body 12 includes an annular ledge 32 for supporting the face insert
14. In a preferred embodiment, the body 12 is formed by investment
casting a titanium alloy. With the face insert 14 in place, the
club head 10 defines a volume of at least 200 cc and more
preferably a volume of at least 300 cc. The volume described herein
is measured according the USGA method of measuring head volume. The
club head 10 has superior durability and club performance,
including a coefficient of restitution (COR) of at least 0.79.
[0076] With reference to FIG. 3, the composite region 16 of the
face insert 14 is configured to have a relatively consistent
distribution of reinforcement fibers across a cross section of its
thickness to facilitate efficient distribution of impact forces and
overall durability. The composite region 16 includes prepreg plies,
each ply having a fiber reinforcement and a resin matrix selected
to contribute to the club's durability and overall performance.
Tests have demonstrated that composite regions formed of prepreg
plies having a relatively low fiber areal weight (FAW) provide
superior attributes in several areas, such as, impact resistance,
durability and overall club performance. More particularly, FAW
values below 140 g/m.sup.2, 100 g/m.sup.2, or 70 g/m.sup.2 or 50
g/m.sup.2, are considered to be particularly effective. Several
prepreg plies having a low FAW can be stacked and still have a
relatively uniform distribution of fiber across the thickness of
the stacked plies. In contrast, at comparable resin content (R/C)
levels, stacked plies of prepreg materials having a higher FAW tend
to have more significant resin rich regions, particularly at the
interfaces of adjacent plies, than stacked plies of lower FAW
materials. It is believed that resin rich regions tend to inhibit
the efficacy of the fiber reinforcement, particularly since the
force resulting from golf ball impact is generally transverse to
the orientation of the fibers of the fiber reinforcement. Preferred
methods of manufacturing, which aid in reducing resin rich regions,
are discussed in detail further below.
[0077] Due to the efficiency of prepreg plies of low FAW, the face
insert 14 can be relatively thin, less than about 10 mm, or less
than about 4.5 mm, or less than about 3.5 mm. Thus, use of the face
insert 14 results in weight savings of about 10 g to 15 g over a
comparable volume of metal used in the body 12 (e.g., Ti-6Al-4V).
As mentioned above, this weight can be allocated to other areas of
the club, as desired. Moreover, the club head 10 has demonstrated
both superior durability and performance. In a durability test, the
club head 10 survived over 3000 impacts of a golf ball shot at a
velocity of about 44 m/sec. In a performance test of the club's
COR, measured in accordance with the United States Golf Association
Rule 4-1a, the club head had a COR of about 0.828.
[0078] With continued reference to FIG. 3, each prepreg ply of the
composite region 16 as a quasi-isotropic fiber reinforcement, and
the plies are stacked in a prescribed order and orientation. For
convenience of reference, the orientation of the plies is measured
from a horizontal axis of the club head's face plane to a line
aligned with the fiber orientation of each ply. A first ply 20 of
the composite region 16 is oriented at 0 degrees, followed by ten
to twelve groups of plies (22, 24, 26) each having four plies
oriented at 0, +45, 90 and -45 degrees, respectively. Thereafter, a
ply 28 oriented at 90 degrees precedes the final or innermost ply
30 oriented at 0 degrees. In this embodiment, the first and final
plies are formed of a prepreg material reinforced by glass fibers,
such as 1080 glass fibers. The remaining plies are formed of
prepreg material reinforced by carbon fiber.
[0079] A suitable carbon fiber reinforcement comprises a carbon
fiber known as "34-700" fiber, available from Grafil, Inc., of
Sacramento, Calif., which has a tensile modulus of 234 GPa (34 Msi)
and tensile strength of 4500 Mpa (650 Ksi). Another suitable fiber,
also available from Grafil, Inc., is a carbon fiber known as
"TR50S" fiber which has a tensile modulus of 240 GPa (35 Msi) and
tensile strength of 4900 Mpa (710 Ksi). Suitable epoxy resins known
as Newport 301 and 350 are available from Newport Adhesives &
Composites, Inc., of Irvine, Calif.
[0080] In a preferred embodiment, the composite region 16 includes
prepreg sheets having a quasi-isotropic fiber reinforcement of
34-700 fiber having an areal weight of about 70 g/m.sup.2 and
impregnated with an epoxy resin (e.g., Newport 301) resulting in a
resin content (R/C) of about 40%. For convenience of reference, the
primary composition of a prepreg sheet can be specified in
abbreviated form by identifying its fiber areal weight, type of
fiber, e.g., 70 FAW 34-700. The abbreviated form can further
identify the resin system and resin content, e.g., 70 FAW
34-700/301, R/C 40%. In a durability test, several plies of this
material were configured in a composite region 16 having a
thickness of about 3.7 mm. The resulting composite region 16
survived over 3000 impacts of a golf ball shot at a velocity of
about 44 m/sec. In another preferred embodiment, the composite
region 16 comprises prepreg plies of 50 FAW TR50S/350. This
material was tested in a composite region 16 having a thickness of
about 3.7 mm and it too survived a similar durability test.
[0081] With reference to FIG. 4, the face insert 14 has sufficient
structural strength that excessive reinforcement along the
interface of the body 12 and the face insert 14 is not required,
which further enhances beneficial weight allocation effects. In
this embodiment, the body 12 is formed of a titanium alloy,
Ti-6Al-4V; however, other suitable material can be used. The face
insert 14 is supported by an annular ledge 32 and is secured with
an adhesive. The annular ledge 32 has a thickness of about 1.5 mm
and extends inwardly between about 3 mm to about 6 mm. The annular
ledge 32 is sufficiently recessed to allow the face insert 14 to
sit generally flush with a transition edge 34 of the body.
Although, in this embodiment, the annular ledge 32 extends around
the periphery of the front opening, it will be appreciated that
other embodiments can utilize a plurality of spaced annular ledges,
e.g., a plurality of tabs, to support the face insert 14.
[0082] With continued reference to FIG. 4, the metallic cap 18 of
the face insert 14 includes a rim 36 about the periphery of the
composite region 16. In a preferred embodiment, the metallic cap 18
may be attached to a front surface of the face insert 14, wherein
the combined thickness of the prepreg plies of the face insert 14
and the metallic cap 18 are no greater than the depth D of the
annular ledge 32 at the front opening of the body 12. The rim 36
covers a side edge 38 of the composite region 16 to further protect
against peeling and delamination of the plies. The rim 36 has a
height substantially the same as the thickness of the face insert
14. In an alternative embodiment, the rim 36 may comprise a series
of segments instead of a continuous cover over the side edge 38 of
the composite region 16. The metallic cap 18 and rim 36 may be
formed, for example, by stamping or other methods known to those
skilled in the art. A preferred thickness of the metallic cap 18 is
less than about 0.5 mm or less than about 0.3 mm. However, in
embodiments having a face insert 14 without a metallic cap 18,
weight savings of about 15 g can be realized.
[0083] In one embodiment, the thickness of the composite region 16
is about 4.5 mm or less and the thickness of the metallic cap 18 is
about 0.5 mm or less. The thickness of the composite region 16 is
about 3.5 mm or less and the thickness of the metallic cap 18 is
about 0.3 mm or less. In some embodiments, the metallic cap
comprises a titanium alloy.
Composite Material Process
[0084] The metallic cap 18 defines a striking face 40 having a
plurality of grooves 42. The metallic cap 18 further aids in
resisting wear from repeated impacts with golf balls even when
covered with sand. A bond gap 44 of about 0.05 mm to 0.2 mm, or
about 0.1 mm, is provided for adhesive attachment of the metallic
cap 18 to the composite region 16. In an alternative embodiment,
the bond gap 44 may be no greater than 0.2 mm. The metallic cap 18
is formed of Ti-6Al-4V titanium alloy; however, other titanium
alloys or other materials having suitable characteristics can be
employed. For example, a non-metallic cap, such as a cap comprising
injection-molded plastic, having a density less than 5 g/cc and a
hardness value of 80 Shore D may be employed.
[0085] As mentioned above, it is beneficial to have a composite
region 16 that is relatively free of resin rich regions. To that
end, fiber reinforcement sheets are impregnated with a controlled
amount of resin to achieve a prescribed resin content. This is
realized, in part, through management of the timing and environment
in which the fiber sheets are cured and soaked.
[0086] The plies can be cut at least twice before achieving the
desired dimensions. A preferred approach includes cutting plies to
a first size, debulking the plies in two compression steps of about
two minutes each. Thereafter, the plies are die cut to the desired
shape, and compressed a third time; this time using a panel
conformed to the desired bulge and roll. The plies are then stacked
to a final thickness and compressed a fourth time with the
conformed panel for about three minutes. The weight and thickness
are measured preferably prior to the curing step.
[0087] The plies can be cut at least twice before achieving the
desired dimensions. A preferred approach includes cutting plies to
a first size and debulking the plies in two compression steps of
about two minutes each. Thereafter, the plies are die cut to the
desired shape, and compressed a third time using a panel conformed
to the desired bulge and roll. The plies are then stacked to a
final thickness and compressed a fourth time with the conformed
panel for about three minutes. The weight and thickness of the
plies are measured preferably prior to the curing step.
[0088] FIGS. 5-7 depict an effective soaking and curing profile for
impregnating plies 70 FAW 34/700 fiber sheet with Newport 301
resin. Soaking and curing occurs in a tool having upper and lower
plates. The tool is pre-layered with a mold release to facilitate
removal of the composite material and is pre-heated to an initial
temperature (T.sub.1) of about 200.degree. F. The initial soak
period is for about 5 minutes, from t.sub.0 to t.sub.1. During the
soak phase, the temperature and pressure remain relatively
constant. The pressure (P.sub.1) is at about 15 psi.
[0089] An alternative soaking and curing profile is depicted in
FIGS. 8 and 9. In this process, the temperature of the tool is
initially about 200.degree. F. (T.sub.1) and upon placement of the
composite material into the tool, the temperature is increased to
about 270.degree. F. (T.sub.2). The temperature is then kept
constant. The initial pressure (P.sub.1) is about 20 psi. The
initial soak period is for about 5 minutes, from t.sub.0 (0 sec.)
to t'.sub.1. The pressure is then ramped up to about 200 psi
(P.sub.2). The post cure phase lasts about 15 minutes (t'.sub.1 to
t'.sub.2) and a final soaking/curing cycle is performed at a
pressure (P.sub.1) of 20 psi for 20 minutes (t'.sub.2 to
t'.sub.3).
Composite Face Roughness Treatment
[0090] In order to increase the surface roughness of the composite
golf club face and to enhance bonding of adhesives used therewith,
a layer of textured film can be placed on the material before
curing. An example of the textured film is ordinary nylon fabric.
Curing conditions do not degrade the fabric and an imprint of the
fabric texture is transferred to the composite surface. Tests have
shown that adhesion of urethane and epoxy, such as 3M.RTM. DP460,
to the treated composite surface was greatly improved and superior
to adhesion to a metallic surface, such as cast titanium alloy.
[0091] In order to increase the surface roughness of the composite
region 16 and to enhance bonding of adhesives used therewith, a
layer of textured film can be placed on the composite material
before curing. An example of the textured film is ordinary nylon
fabric. Curing conditions do not degrade the fabric and an imprint
of the fabric texture is transferred to the composite surface.
Tests have shown that adhesion of urethane and epoxy, such as
3M.RTM. DP460, to a composite surface treated in such a fashion was
greatly improved and superior to adhesion to a metallic surface,
such as cast titanium alloy.
[0092] A face insert 14 having increased surface roughness may
comprise a layer of textured film co-cured with the plies of low
FAW material, in which the layer of textured film forms a front
surface of the face insert 14 instead of the metallic cap 18. The
layer of textured film preferably comprises nylon fabric. Without
the metallic cap 18, the mass of the face insert 14 is at least 15
grams less than a face insert of equivalent volume formed of the
metallic material of the body 12 of the club head 10.
[0093] Typically, adhesion of the 3M.RTM. DP460 adhesive to a cast
metallic surface is greater than to an untreated composite surface.
Consequently, when the face structure fails on impact, the adhesive
peels off the composite surface but remains bonded to the metallic
surface. After treating a composite surface as described above, the
situation is reversed [-] and the 3M.RTM. DP460 peels off the
metallic surface but remains bonded to the composite surface.
[0094] The enhanced adhesion properties of this treatment
contribute to an improved fatigue life for a composite golf club
face. In a test, a club head having an untreated face insert 14 and
a COR of about 0.847 endured about 250 test shots before
significant degradation or failure occurred. In contrast, a similar
club head having a treated face insert 14 and a COR of about 0.842
endured over 2000 shots before significant degradation or failure
occurred.
[0095] Alternatively, the means for applying the composite texture
improvement may be incorporated into the mold surface. By doing so,
the textured area can be more precisely controlled. For simple face
plate joining to the opening of a cast body, the texture can be
formed in surfaces where shear and peel are the dominant modes of
failure.
[0096] It should be appreciated from the foregoing that the present
invention provides a club head 10 having a composite face insert
(or face portion) 14 attached to a metallic body 12, forming a
volume of at least 200 cc and providing superior durability and
club performance. To that end, the face insert 14 comprises prepreg
plies having a fiber areal weight (FAW) of less than 100 g/m.sup.2.
The face insert 14 has a thickness less than 6 mm and has a mass at
least 10 grams less than a face insert of equivalent volume formed
of the metallic material of the body 12 of the club head 10. The
coefficient of restitution for the club head 10 is at least
0.79.
[0097] Alternatively, the face insert 14 may comprise any
non-metallic material having a density less than a metallic
material of the body 12 along with a metallic cap 18 covering a
front surface of the face insert 14 and having a rim 36. For
example, the face insert 14 of the present invention may comprise a
composite material, such as a fiber-reinforced plastic or a
chopped-fiber compound (e.g., bulk molded compound or sheet molded
compound), or an injection-molded polymer either alone or in
combination with prepreg plies having low FAW. The thickness of the
face insert 14 may be substantially constant or it may comprise a
variation of at least two thicknesses, one being measured at a
geometric center and another measured near a periphery of the face
insert 14. In one embodiment, for example, an injection-molded
polymer disk may be embedded in a central region of a plurality of
low FAW prepreg plies. The total thickness of the face insert 14
may range between about 1 mm and about 8 mm, and between about 2 mm
and about 7 mm, or between about 2.5 mm and about 4 mm, or between
about 3 mm and about 4 mm.
[0098] In addition, the body 12 of a club head 10 in the present
invention may be formed of a metallic material, a non-metallic
material or a combination of materials, such as a steel skirt and
sole with a composite crown, for example. Also, one or more weights
may be located in or on the body 12, as desired, to achieve final
performance characteristics for the club head 10.
[0099] FIG. 10A illustrates a hollow iron golf club head 1000
including a heel 1002, toe 1004, sole portion 1008, and top line
portion 1006. The striking face 1010 includes scoreline grooves
1012 that are designed for impact with the golf ball. The
scorelines described in the embodiments herein can be molded into a
composite face insert. In some embodiments, the golf club head 1000
body can be a single unitary cast piece that is adhesively attached
to a striking face 1010 that is formed separately. In certain
embodiments, the striking face 1010 is a composite insert as will
be described in further detail below.
[0100] FIGS. 10A and 10B also show a center point 1001 being an
ideal striking point in the center of the striking face 1010 and
respective orthogonal center of gravity (hereinafter, "CG") axes. A
CG x-axis 1005, CG y-axis 1007, and CG z-axis 1003 intersect at the
center point 1001. In addition, a CG z-up axis 1009 is defined as
an axis perpendicular to the ground plane 1011 and having an origin
at the ground plane 1011. The ground plane 1011 is assumed to be a
perfectly flat plane.
[0101] In certain embodiments, a desirable CG-x location is between
about 5 mm (heel side) and about -5 mm (toe side) along the CG
x-axis 1005. A desirable CG-y location is between about 5 mm to
about 20 mm along the CG y-axis 1007 toward the rear portion of the
club head. Additionally, a desirable CG-z location is between about
12 mm to about 25 mm along the CG z-up axis 1009, as previously
described.
[0102] FIG. 10B illustrates an elevated toe view of the golf club
head 1000 including a back portion 1028, a front portion 1030, a
sole portion 1008, a top line portion 1006, and a striking face
1010, as previously described. The front surface of the striking
face 1010 is contained within a face plane 1025.
[0103] FIG. 11 illustrates a cross-sectional view according to one
exemplary embodiment. The club head 1100 includes a back portion
1106, a top line portion 1104, a front portion 1102 and a sole
portion 1108. A composite striking face 1112 is located on the
front portion 1102 of the body. In other words, the body includes a
front opening that receives the composite striking face 1112. After
adhesively attaching the composite face 1112, an interior cavity
1114 is formed. The club head 1100 back portion 1106 further
includes a rear wall having an upper rear wall 1132 and a lower
rear wall 1128, and a sound and vibration dampening badge 1130. The
back portion 1106 also includes a rear protrusion 1124, an upper
edge 1126, and a sole thickness 1122.
[0104] FIG. 11 further shows the front opening of the club head
body having a ledge 1134 extending around an entire periphery of
the front opening of the body. It is understood that the ledge 1134
can be continuous or intermittently located around a periphery of
the front opening. In one embodiment, the ledge 1134 is
perpendicular to a front opening wall 1136. In one embodiment, the
ledge extends inwardly toward a center region of the face by a
ledge distance 1118 of about 1 mm to about 5 mm, or about 3 mm to
about 4 mm. Similarly, the front opening wall 1136 extends
perpendicularly away from a plane of the striking face by a depth
distance 1120 between about 1 mm to about 5 mm, or between 3 mm to
about 4 mm.
[0105] In addition the striking insert 1112 includes a varying
thickness and a thickened peripheral portion having a third
thickness dimension 1110. The composite insert 1112 includes a
first thickness 1111 at the thinnest region of the striking insert
1112 and a second thickness 1116 located in a central region of the
striking insert 1112. The second thickness 1116 is the thickest
dimension within the central region of the striking insert 1112. In
one embodiment, the second thickness 1116 is greater than the first
thickness 1111 and less than the third thickness 1110 of the
peripheral portion. The third thickness 1110 located in a
peripheral portion of the striking insert 1112 is greater than both
the second thickness 1116 and the first thickness 1111. The
peripheral region of the striking insert 1112 having the third
thickness 1110 is attached to the ledge 1134.
[0106] In one embodiment, the first thickness 1111 can be between
about 1.5 mm and about 2.0 mm, with a preferred thickness of about
2 mm or less. The second thickness 1116 can be between about 2 mm
and about 3 mm and the third thickness 1110 is between about 3 mm
and about 4.5 mm, or about 3.5 mm to about 4.0 mm.
[0107] Alternatively, variable thickness configurations or inverted
cone configurations can be implemented in the striking face 1112 as
discussed in U.S. Pat. Nos. 6,800,038, 6,824,475, 6,904,663, and
6,997,820, all incorporated herein by reference in their
entirety.
[0108] In the examples described herein, a composite face insert
can have a striking surface area in a range of about 2,700 mm.sup.2
to about 5,000 mm.sup.2. The unsupported surface area (surface area
on the rear surface of the striking insert that is not engaged with
a supporting surface) of the composite face insert can be within a
range of about 300 mm.sup.2 to about 4,000 mm.sup.2, or 450
mm.sup.2 to about 3,500 mm.sup.2. In some embodiments, the
unsupported surface area is at least greater than about 2,000
mm.sup.2. The unsupported surface area is the portion of the
composite insert that is defined by the first thickness 1111 and
second thickness 1116 excluding the peripheral portion. The
composite face thickness can be within a range of about 1 mm to
about 8.0 mm, or about 2.5 to about 6 mm. In certain embodiments,
the composite face thickness is less than about 5.5 mm. In
embodiments having a thickened region, the thickened region surface
area can range from about 230 mm.sup.2 to about 2,000 mm.sup.2.
[0109] FIG. 12 illustrates an alternative embodiment of a golf club
head 1200 including a front portion 1202, a rear portion 1206, a
sole portion 1208 and a top line portion 1204. The club head 1200
includes a front opening located in the front portion 1202. The
club head 1200 further includes a composite striking insert 1216, a
gap cavity 1218, a back wall 1214, and a peripheral front opening
wall 1210. The composite striking insert 1216 includes a first
thickness 1222, a second thickness 1220, and a third thickness
1224. The third thickness 1224 corresponds to a thickened end
portion 1212 of the striking insert 1216.
[0110] The back wall 1214 includes a front engaging surface 1214a
which provides support for the composite insert 1216 to be
adhesively attached. The front engaging surface 1214a and the
peripheral front opening wall 1210 create the front opening to
receive the composite striking insert 1216. The front engaging
surface 1214a is offset from the front surface 1230 of the club
head by an offset distance 1226. The offset distance 1226 can be
between about 1 mm and about 5 mm or about 4 mm.
[0111] The offset distance 1226 is greater than or equal to the
third thickness 1224 of the striking insert 1216 to enable the
striking insert 1216 to sit within the front opening. The striking
insert 1216 is located within the front opening so that the front
striking insert 1216 surface is flush with the front portion
surface 1230 of the club head body 1200. The interior gap cavity
1218 is located between the striking insert 1216 and the front
engaging surface 1214a of the back wall 1214 and can be about 0.1
cc to about 20 cc. In one embodiment, the interior cavity is less
than about 10 cc.
[0112] The interior cavity is entirely defined and surrounded by
the striking insert 1216 and the rear back wall 1214 only. The back
wall 1214 is in direct adhesive contact with the striking insert
1216 and supports the striking insert 1216. In other words, the
thickened peripheral region 1212 of the striking insert is in
direct contact with an interior surface of the back wall 1214.
[0113] It is critical that the central region of the striking
insert 1216 is not capable of making direct contact with the back
wall 1214 upon impact with the golf ball to avoid unwanted sound
and unwanted performance effects. Therefore, a critical distance
1228 of about 1 mm or more is maintained between the front engaging
surface 1214a and a rear surface 1216a of the striking insert 1216
at a maximum second thickness 1220 location.
[0114] FIG. 13A illustrates another exemplary embodiment according
to another alternative embodiment of a golf club head 1300
including a front portion 1302, a back portion 1306, a sole portion
1308, and a top line portion 1304. The golf club head also includes
a badge 1330, back wall portion 1332, an interior back wall surface
1328, a protruding portion 1324, an upper edge 1326, a sole
thickness 1320, a ledge 1322, a front opening wall 1310, an
interior cavity 1334, and a striking insert 1312. The ledge 1322
extends a distance 1316 inwardly and the front opening wall 1310
also extends a distance 1318 as previously described.
[0115] The striking insert material, of the embodiments described
herein, are made of the processes and materials described above but
can also be a composite material as described in U.S. patent
application Ser. Nos. 10/831,496 (now U.S. Pat. No. 7,140,974),
11/642,310, 11/825,138, 11/998,436, 11/823,638, 12/004,386,
12/004,387, 11/960,609, 11/960,610, and 12/156,947, which are
incorporated herein by reference in their entirety. All of the
composite inserts described herein can be made according to the
processes and composite materials described within the above listed
patents and patent applications. For example, in one embodiment, a
composite face insert material having a fiber areal weight of less
than 200 g/m.sup.2 is utilized. In another embodiment, a face
insert material has a fiber areal weight less than 100 g/m.sup.2.
In yet other embodiments, the face insert material has a fiber
areal weight less than 150 g/m.sup.2.
[0116] For example, water jet cutting can be utilized to cut the
composite face inserts from a sheet of composite material as
described in the patents and patent applications incorporated by
reference. In addition, the face insert can be formed by CNC
cutting
[0117] Some examples of composites that can be used to form the
components include, without limitation, glass fiber reinforced
polymers (GFRP), carbon fiber reinforced polymers (CFRP), metal
matrix composites (MMC), ceramic matrix composites (CMC), and
natural composites (e.g., wood composites). The face insert may
also be made of a thermoplastic material, as described herein. In
certain embodiments, the composite face inserts described herein
are made of a material having a density less than about 1.5 g/cc or
less than 2.7 g/cc. By contrast, the golf club head material
supporting the face insert can be a titanium material having a
density greater than 4 g/cc.
[0118] FIG. 13A shows a center cross-sectional view of the striking
insert 1312 being a constant thickness 1314 (across the face of the
striking insert 1312) and the constant thickness 1314 being between
about 3.0 mm to about 5.0 mm, or about 3.5 mm to about 4.5 mm.
[0119] FIG. 13B is a detailed view of a lower portion of the golf
club head 1300 shown in FIG. 13A. FIG. 13B shows a non-undercut
design. Specifically, a lower leading edge zone 1346 of the club
head body is completely filled with material and does not include
an undercut or gap within the lower leading edge zone 1346 in a
transition region between the striking surface of the club face and
the sole portion 1308.
[0120] FIG. 13B shows a club face plane 1336 which contains the
striking surface and is co-planar with the striking surface.
Furthermore, the ledge 1322 includes a front engaging surface 1344
that is contained within a ledge plane 1338. The club face plane
1336 and the ledge plane 1338 are substantially parallel with
respect to one another. A segment 1342 of the sole portion 1308 is
located between the face plane 1336 and the ledge plane 1338.
[0121] The lower leading edge zone 1346 is defined by the front
opening wall 1310, the ledge plane 1338, the club face plane 1336,
and the sole portion segment 1342. Within the lower leading edge
zone 1346, an undercut or gap is avoided in order to lower the
first leading edge groove centerline axis 1348 with respect to the
ground 1301. The leading edge groove centerline axis 1348 is
defined as the intersection of a bisectional plane 1352 and the
club face plane 1336 at the centerline axis 1348 shown in FIG.
13B.
[0122] A low leading edge groove centerline axis 1348 is beneficial
in allowing a golfer to make engaging contact with a ball sooner
upon impact. In addition, a lower leading edge groove centerline
axis 1348 may have additional benefits when a golfer mis-hits a
ball by improving the quality of contact between the ball and the
leading groove or lowest groove.
[0123] A horizontal plane 1350 contains the leading edge groove
centerline axis 1348 and is parallel with the ground surface 1301.
The height distance, h, between the horizontal plane 1350 of the
leading edge groove axis 1348 and the ground surface 1301 is
between about 4 mm and about 10 mm. In certain embodiments, the
height distance, h, is between about 4 mm and about 8 mm or between
about 4 mm and about 6 mm.
[0124] FIG. 14A illustrates a magnified view 1400 of the junction
between a composite face insert 1404 and a ledge 1418, according to
one exemplary embodiment. The composite face insert 1404 includes
an end wall 1410 and a rear surface wall 1412. The composite face
insert 1404 is attached to a front opening wall 1408 and front
ledge surface 1406 by an adhesive 1414. The adhesive 1414 is
applied over a majority of the interface between the composite face
insert 1404 and the front opening wall 1408 and front ledge surface
1406.
[0125] The front ledge surface 1406 intersects with the front
opening wall 1408 at a rounded corner location 1416. The corner
1416 includes a radius of between about 0.1 mm and about 0.5 mm. In
certain embodiments, the radius is at least about 0.30 mm or
greater. A larger corner 1416 radius will avoid high stress
concentrations that may result in material failure of the ledge
1418 after repeated use.
[0126] The rear bond gap distance, x, is located between the front
ledge surface 1406 and the rear surface wall 1412. The rear bond
gap distance, x, is measured along an axis that is perpendicular to
the face plane toward a rear portion of the club head.
[0127] The side bond gap distance 1402 between the end wall 1410
and the front opening wall 1408 is between 0.1 mm and 0.5 mm, or
about 0.3 mm or less. In one embodiment, the side bond gap distance
1402 and the rear bond gap distance, x, are filled with an adhesive
epoxy to attach the composite insert 1404.
[0128] In certain embodiments, the rear bond gap distance, x, is
equal to or greater than the side bond gap distance 1402. In some
embodiments, the rear bond gap distance, x, is in accordance with
the following inequality:
x.gtoreq.0.2 mm Eq. 1
[0129] In the above inequality, the side bond gap distance 1402 is
set at a distance of about 0.2 mm. If the rear bond gap distance,
x, follows the inequality of Equation 1 described above, the
composite face insert 1404 will be securely attached within the
front opening. Without maintaining a rear bond gap distance, x,
larger than the side bond gap distance 1402, the composite face
insert 1404 may become loose after repeated impacts and
bending.
[0130] FIG. 14A also shows a metallic cap 1420 which can be
implemented in any of the embodiments described herein. The
metallic cap 1420 can be made of a material having a density less
than 9 g/cc or less than 5 g/cc such as a titanium alloy, CP
titanium, or a nickel based alloy. In addition, the metallic cap
1420 can be a Ni--Cr or Co--Ni alloy with a chrome plated layer
formed by electro-plating or electro-forming.
[0131] FIG. 14B further shows another embodiment similar to FIG.
14A except the metallic cap 1420 is replaced by a polymer or
polyurethane front layer 1421 having grooves incorporated thereon.
The polymer or polyurethane material can be of the type described
in U.S. patent application Ser. No. 11/960,609, already
incorporated by reference in its entirety. Both the metallic cap
1420 and polymer or polyurethane layer 1421 cover the entire front
surface of the face insert 1404.
[0132] FIG. 15A illustrates an alternative embodiment 1500
including a composite face insert 1504, a ledge 1518, an end wall
1510, a rear surface wall 1512, a front opening wall 1508, front
ledge surface 1506, an adhesive 1514 and a corner 1516, as
previously described. The face insert 1504 can include a metallic
cap or polyurethane cover as previously described.
[0133] However, the embodiment shown in FIG. 15A includes an
additional step gap 1522 in addition to a side bond gap distance
1502 or bond gap. The side bond gap distance 1502 and the step gap
1522 (measured along an axis parallel to the face plane) create a
total engineering gap 1520. The step gap 1522 is created by a step
region 1524. The step region 1524 and step gap 1522 are present
about the entire circumference of the front opening wall 1508.
[0134] As shown, the side bond gap 1502 and step gap 1522 are
filled with the adhesive 1514. The adhesive 1514 in the front
portion parallel with the face plane to avoid unwanted bumps or
sharp edges on the striking face.
[0135] In one embodiment, the total engineering gap 1520 is about
0.5 mm and the side bond gap distance 1502 is about 0.2 mm. As a
result, the step gap 1522 is about 0.3 mm. The total engineering
gap 1520 can be between about 0.2 mm and about 1 mm or between
about 0.2 mm and about 0.8 mm.
[0136] The engineering gap 1520 enables the composite face insert
1504 to be attached without maintaining a perfect side bond gap
distance 1502 about the entire circumference of the face insert
1504. For example, the embodiment of FIGS. 14A and 14B, without a
step gap and engineering gap would require the exact placement of
the composite face insert centered within the front opening to
achieve a consistent side bond gap distance. An inconsistent side
bond gap distance, without an engineering gap, would be clearly
seen by the user and would have a negative impact on aesthetic
appeal and performance parameters. In other words, the composite
face insert without an engineering gap may look off-center to the
golfer and negatively impact the golfer's performance.
[0137] FIG. 15B is a front view of a composite face insert with an
engineering gap 1520. The side bond gap distance 1502 and step gap
1522 are also shown. Within the face plane, the engineering gap
1520, the side bond gap distance 1502, and the step gap 1522 are
measured along an axis that is perpendicular to the end wall 1510
at any given point along the outer peripheral edge of the composite
face insert 1504 (within the face plane). The front opening wall
1508 is shown in dashed lines from a front perspective.
[0138] The above described engineering gap distance, side bond gap
distance and step gap distance can be applied to any of the
embodiments described herein. It is understood that the gaps shown
in FIG. 15B are exaggerated for clarity.
[0139] FIGS. 16-18 illustrate similar embodiments to FIGS. 11-13B,
having similar features except the club heads are filled with a
filler material.
[0140] FIG. 16 illustrates a cross sectional view of an alternative
embodiment of a golf club head 1600. The cross section is taken
through an ideal striking point in the center of the striking face
as previously described.
[0141] The club head 1600 includes a front portion 1602, back
portion 1606, a top line portion 1604, and a sole portion 1608. The
club head 1600 further includes an upper back wall 1632, a lower
back wall 1628, a badge 1630, a sole thickness 1622, a rear
protrusion 1624, and filler material 1614. The badge 1630 is
positioned above an upper edge 1626 and covers an aperture 1638
used for introducing the plug 1640 and filler material 1614 into
the interior cavity of the club head 1600. The filler material 1614
and plug 1640 can be of the same configuration, material, and
keying design as described in U.S. patent application Ser. No.
12/462,198, incorporated by reference herein, in its entirety.
[0142] FIG. 16 further shows a front opening wall 1636, a ledge
distance 1618, a depth distance 1620, a first thickness 1611, a
second thickness 1616, a third thickness 1610, a ledge 1634, and a
composite face insert 1612, previously described.
[0143] In one embodiment, the filler material can be an expandable
foam such as Expancel.RTM. 920 DU 40 which is an acrylic copolymer
encapsulating a blowing agent, such as isopentane. A copolymer is
greater than about 75 weight percent of the composition and the
blowing agent is about 15-20 weight percent. The unexpanded
particle size of the filler material can be between about 2 .mu.m
and about 90 .mu.m depending on the context.
[0144] In one embodiment, the density of the filler material is
between about 0.16 g/cc and about 0.19 g/cc. In certain
embodiments, the density of the filler material is in the range of
about 0.03 g/cc to about 0.2 g/cc, or about 0.04-0.10 g/cc. The
density of the filler material impacts the COR, durability,
strength, and filling capacity. In general, a lower density
material will have less of an impact on the COR of a club head. The
filler material can have a hardness range of about 15-85 Shore OO
hardness or about 80 Shore OO hardness or less.
[0145] In one embodiment, the filler material is subject to heat
for expansion of about 150.degree. C.+/-10.degree. C. for about 30
minutes. In some embodiments, the expansion of the filler material
can begin at about 125.degree. C. to about 140.degree. C. A maximum
expansion temperature range can be between about 160.degree. C. to
about 190.degree. C. The temperature at which the expansion of the
filler material begins is critical in preventing unwanted expansion
after the club head is assembled. For example, a filler material
that begins expanding at about 120.degree. C. will not cause
unwanted expansion when the club is placed in the trunk of a car
(where temperatures can reach up to about 83.degree. C.). Thus, a
filler material that has a beginning expansion temperature of
greater than about 80.degree. C. is preferred.
[0146] Some other examples of materials that can be used as a
filler material or plug material include, without limitation:
viscoelastic elastomers; vinyl copolymers with or without inorganic
fillers; polyvinyl acetate with or without mineral fillers such as
barium sulfate; acrylics; polyesters; polyurethanes; polyethers;
polyamides; polybutadienes; polystyrenes; polyisoprenes;
polyethylenes; polyolefins; styrene/isoprene block copolymers;
metallized polyesters; metallized acrylics; epoxies; epoxy and
graphite composites; natural and synthetic rubbers; piezoelectric
ceramics; thermoset and thermoplastic rubbers; foamed polymers;
ionomers; low-density fiber glass; bitumen; silicone; and mixtures
thereof. The metallized polyesters and acrylics can comprise
aluminum as the metal. Commercially available materials include
resilient polymeric materials such as Scotchdamp.TM. from 3M,
Sorbothane.RTM. from Sorbothane, Inc., DYAD.RTM. and GP.RTM. from
Soundcoat Company Inc., Dynamat.RTM. from Dynamat Control of North
America, Inc., NoViFlex.TM. Sylomer.RTM. from Pole Star Maritime
Group, LLC, Isoplast.RTM. from The Dow Chemical Company, and
Legetolex.TM. from Piqua Technologies, Inc. In one embodiment the
filler material may have a modulus of elasticity ranging from about
0.001 GPa to about 25 GPa, and a durometer ranging from about 5 to
about 95 on a Shore D scale. In other examples, gels or liquids can
be used, and softer materials which are better characterized on a
Shore A or other scale can be used. The Shore D hardness on a
polymer is measured in accordance with the ASTM (American Society
for Testing and Materials) test D2240.
[0147] In certain embodiments, the interior cavity of the club head
1600 can includes the plug 1640 for absorbing vibration. It is
understood, that an embodiment without the plug 1640 is within the
scope of the present description.
[0148] After the plug 1640 is frictionally engaged in a position,
the filler material 1614 can be inserted into the cavity. In
certain embodiments, the plug 1640 is a polymeric material.
[0149] In one embodiment, the plug 1640 material is a urethane or
silicone material having a density of about 0.95 g/cc to about 1.75
g/cc, or about 1 g/cc. The plug 1640 can have a hardness of about
10 to about 70 shore A hardness. In certain embodiments, a shore A
hardness of about 40 or less is preferred.
[0150] The filler material 1614 can be an expanding foam material
that is expanded by a certain amount of heat as previously
described. The filler material 1614 expands and fills a relatively
large volume, greater than the volume occupied by the plug
1640.
[0151] In some embodiments, the volume of the cavity is between
about 1 cc and about 200 cc, or between about 10 cc and about 20
cc. For the purposes of measuring the cavity volume herein, the
aperture 1638 is assumed to be removed from the back wall 1632 and
an imaginary continuous back wall or substantially planar back wall
is utilized to calculate the cavity volume.
[0152] In some embodiments, the filler material 1614 occupies about
50% to about 99% of the total club head cavity volume while the
plug 1640 occupies between about 0% to about 20% of the total
cavity volume. In specific embodiments, the plug 1640 occupies
between about 0.1 cc and 1 cc with the remainder of the cavity
volume being filled by the filler material 1614. It is understood
that any of the embodiments described herein can be provided
without a plug and filler material.
[0153] In order to achieve a desirable CG location, the filler
material 1614 and plug 1640 must be lightweight. In certain
embodiments, the total mass of the filler material 1614 and plug
1640 is less than about 5 g or between about 2 g and about 4 g. In
one embodiment, the total weight of the filler material 1614 and
the plug 1640 is 10 g or less or about 3 g or less. In certain
embodiments, the total weight of the filler material 714 and plug
1640 is less than 2% of the total weight of the club head 1600
(excluding any badges, filler material/plug, and ferrule ring). In
other embodiments, the total weight of the filler material 714 and
plug 1640 is less than about 10% of the total weight of the club
head 1600.
[0154] In some embodiments, the total weight of the filler material
1614 and plug 1640 is between about 1% and about 5% of the total
weight of the club head (excluding the badges, filler
material/plug, and ferrule ring). Thus, a desirable CG location is
still attainable while improving the sound and feel of the golf
club head. In certain embodiments, the plug 1640 can weigh about
0.5 g to about 1 g and the filler material 1614 can weigh about 5
grams or less. In some embodiments, the plug 1640 weighs about 0.7
g or less. In other embodiments, the plug 1640 can be equal to or
heavier than the total filler material weight.
[0155] In yet other embodiments, the filler material 1614 and the
plug 1640 have a combined weight of less than 20% of the total club
head weight (excluding badges, filler material/plug, and ferrule
ring). In one embodiment, the combined weight of the filler
material 1614 and plug 1640 is less than 5%.
[0156] FIG. 17 illustrates an alternative embodiment of a golf club
head 1700 including a front portion 1702, a rear portion 1706, a
sole portion 1708 and a top line portion 1704. The club head 1700
includes a front opening located in the front portion 1702. The
club head 1700 further includes a composite striking insert 1716,
filler material 1718, a back wall 1714, and a peripheral front
opening wall 1710. It is possible to include a plug, badge, and
aperture as described above. The striking insert 1716 includes a
first thickness 1722, a second thickness 1720, and a third
thickness 1724. A critical distance 1728 having dimensions
described above is also present. The peripheral region 1712 is in
contact with the front surface of the rear wall 1714. The front
surface of the rear wall 1714 is located at an offset distance
1726, previously described.
[0157] The filler material 1718 can be of the type already
described above or can be a thermoplastic elastomer having a
density of about 0.9 g/cc to about 1.20 g/cc.
[0158] FIG. 18 shows a top line portion 1804, back portion 1806,
front portion 1802, sole portion 1808, back wall portion 1832,
badge 1830, interior back wall surface 1828, upper edge 1826,
protruding portion 1824, ledge 1822, sole thickness 1820, offset
distance 1818, ledge distance 1816, constant face thickness 1814,
front opening wall 1810, and filler material 1834, as previously
described.
[0159] In certain embodiments, the badges and composite face
inserts, described herein, can be adhesively attached with epoxy or
any known adhesive. For example, an epoxy such as 3M.RTM. DP460 can
be used. It is possible for the badge 1830 to be mechanically
attached to the back portion 1806 of the club head 1800.
[0160] After the hollow iron 1800 is filled with the filler
material 1834, the badge 1830 is adhesively or mechanically
attached to the back wall 1832 to cover or occlude the aperture to
prevent filler material from leaving the cavity and also to achieve
a desired aesthetic and while creating further dampening.
[0161] In some embodiments, the COR is greater than about 0.790.
The COR is at least 0.80 as measured according to the USGA Rules of
Golf based on a 160 ft./s ball speed test and the USGA calibration
plate. The COR can even be as high as 0.83.
[0162] In one embodiment, the body portion is made from 17-4 steel.
However another material such as carbon steel (e.g., 1020, 1030,
8620, or 1040 carbon steel), chrome-molybdenum steel (e.g., 4140
Cr--Mo steel), Ni--Cr--Mo steel (e.g., 8620 Ni--Cr--Mo steel), or
austenitic stainless steel (e.g., 304, N50, or N60 stainless steel,
410 stainless steel) can be used.
[0163] The components of the described components disclosed in the
present specification can be formed from any of various suitable
metals or metal alloys.
[0164] In addition to those noted above, some examples of metals
and metal alloys that can be used to form the components of the
parts described include, without limitation: titanium alloys (e.g.,
3-2.5, 6-4, SP700, 15-3-3-3, 10-2-3, or other alpha/near alpha,
alpha-beta, and beta/near beta titanium alloys), aluminum/aluminum
alloys (e.g., 3000 series alloys, 5000 series alloys, 6000 series
alloys, such as 6061-T6, and 7000 series alloys, such as 7075),
magnesium alloys, copper alloys, and nickel alloys.
[0165] The body portion can include various features such as
weighting elements, cartridges, and/or inserts or applied bodies as
used for CG placement, vibration control or damping, or acoustic
control or damping. For example, U.S. Pat. No. 6,811,496,
incorporated herein by reference in its entirety, discloses the
attachment of mass altering pins or cartridge weighting
elements.
[0166] FIG. 19 shows a golf club head 1900 having a heel 1902, toe
portion 1904, sole portion 1908, top line portion 1906, striking
face 1910, scoreline grooves 1912, a center point 1901, a CG x-axis
1905, a CG z-axis 1903, a CG z-up axis, a ground plane 1911 as
previously described in FIG. 10A.
[0167] However, the composite face insert 1916 does not extend
across the striking surface to a toe portion 1904 edge 1920 as
shown in FIG. 19. The composite face insert 1916 occupies about 50%
to about 90% of the front striking surface plane. Subsequently,
about 50% to about 10% of the front striking surface plane is
comprised of the metallic material similar to the golf club head
body.
[0168] Including a smaller percentage of composite face insert 1916
striking surface area can result in a significant reduction in
manufacturing cost and composite material savings.
[0169] At least one advantage of the present invention is that a
lightweight composite face insert will provide an improved CG club
head location.
[0170] In addition, a certain engineering gap can be utilized to
reduce the manufacturing time and expense associated with perfectly
centering a composite face insert in a front opening of the golf
club head.
[0171] At least another advantage of the embodiments described
above, is that a rear back wall and badge can act to create an
enclosed cavity behind the composite face so that the ledge and
adhesive material used to bond the face insert to the club body is
not visible to the user.
[0172] At least another advantage of the embodiments described is
that a lightweight filler material arrangement is created allowing
the center of gravity of the hollow iron construction to remain low
while improving the sound and feel of the club during use.
[0173] The embodiments described herein conform with the USGA
(United States Golf Association) Rules of Golf and Appendix II, 5c
related to the Determination of Groove Conformance (issued in
August 2008). For example, clubs having a loft of 25 degrees or
higher meets the groove width, groove depth, groove separation,
groove consistency, area limitations, and edge radius requirements
set forth by the USGA. In the embodiments described herein, less
than 50% of measured values of Area/(Width+Separation) are greater
than 0.0030 in.sup.2/in and no single measured value of
Area/(Width+Separation) value for any single groove is greater than
0.0032 in.sup.2/in.
[0174] With respect to a groove edge radius, the groove edges are
in the form of a radius having an effective radius not less than
0.010'' as described by the two circles method described in the
USGA rules. In addition, the effective radius is not greater than
0.020''. In the embodiments described, less than 50% of the upper
groove edges or lower groove edges fails the two circles method
subject to a 10 degree angular allowance as described in the USGA
rules. No single groove edge protrudes more than 0.0003'' outside
the outer circle.
[0175] In some examples, golf club heads are described with
reference to a Coefficient of Restitution (COR) that is based on a
ratio of a difference between ball speed and club head speed after
impact to club head speed prior to impact. A COR of 1 corresponds
to a maximum theoretical ball speed and a COR of 0 corresponds to a
ball and club head moving together after impact. A COR of 0.83 or
less is a suitable design goal for most club heads to insure
compliance with USGA rules. Club heads can also be described with
reference to a Characteristic Time (CT) that is associated with a
time duration in which an object remains in contact with a club
face. A CT of about 257 .mu.s or less is a suitable design goal,
corresponding to a current USGA limit of 239 .mu.s plus a USGA
tolerance of 18 .mu.s. Thinner club faces tend to be associated
with relatively larger COR and CT values.
[0176] Wood type golf club heads generally have dimensions selected
to conform to USGA requirements. A wood type golf club head that
conforms to USGA Rules can have dimensions no greater than about
71.1 mm from club sole to club crown, 127 mm from club toe to club
heel, and 127 mm from club face to a backmost portion of the club
head when held in a standard address position. In addition, total
club head volume cannot exceed 470 cm.sup.3, including a 10
cm.sup.3 tolerance.
[0177] At club head/golf ball impact, a club striking face is
deformed so that vibrational modes of the club head associated with
the club crown, sole, or striking face are excited. The geometry of
most golf clubs is complex, consisting of surfaces having a variety
of curvatures, thicknesses, and materials, and precise calculation
of club head modes may be difficult. Club head modes can be
calculated using computer-aided simulation tools. For any
manufactured club heads, and acoustic signal produced with
ball/club impact can be evaluated as described below to select
suitable club head characteristics for a desired club sound. Some
club heads that are suitable for the following methods are
described in U.S. patent application Ser. No. 11/960,609, filed
Dec. 19, 2007.
[0178] Generally, club face acoustic modes at frequencies less than
about 3 kHz, 3.5 kHz, or 3.8 kHz are associated with unpleasant
sounds when used to strike a golf ball. Acoustic modes at these
frequencies in the sole or crown can also cause a club to have an
unpleasant sound. Conventional titanium or steel faces tend to
exhibit such resonance frequencies due to the combination of
material density, striking plate thickness, and elastic constant
for the large club faces preferred by many golfers. However, with a
composite striking plate, material properties are substantially
changed so that face acoustic resonance frequencies can be raised
to frequencies of 3.9 kHz, 4.0 kHz, 4.5 kHz, or higher, thereby
providing golf clubs that have satisfactory sound characteristics.
Because sound quality is particularly significant for driver type
clubs, such clubs are discussed herein but other clubs such as
fairway woods can be similarly configured, but these clubs have
much less tendency to produce unpleasant sounds.
[0179] Referring to FIG. 20, a method 2000 of evaluating club head
sound and modifying a club head based on the evaluation includes
making a golf ball and club head impact at 2002 under conditions
related to actual play. For example, a golfer can be directed to
strike a ball with a club using her normal golf swing, and the
sound produced thereby recorded and stored at 2004. Club/ball
impact speed can be varied by selecting golfer with differing swing
speeds, generally in range of about 50 mph to about 130 mph. Higher
swing speeds tend to produce more sound and thus can be more
conveniently analyzed. At 2006, a time-varying spectrum is obtained
that includes amplitudes (as a function of time) of the various
frequency components of the recorded acoustic signal. A complex set
of frequency components is generally produced at 2006, and in a
step 2008 one or more club head surfaces are selected to determine
if one or more frequency components should be associated with
particular club head surfaces. For example, at 2008, club head
surface displacements for a club head striking surface at one or
more selected frequencies (based on the frequency components
determined at 2006) are determined by measuring surface vibration
or otherwise determined or estimated. At some frequencies, the
selected surface (for example, the striking surface) can exhibit
little displacement so that this frequency component should be
associated with some other club head surface. In some cases, a low
or lowest order vibration mode of the striking surface can be
observed based on a striking surface displacement pattern. A lowest
order mode of a club face is associated with a relatively large
displacements at the selected frequency at a striking face center
and relatively small (or no) displacements at the striking face
perimeter. At 2010, one or more frequencies are associated with a
mode of a particular surface. At 2012, a characteristic of the
selected surface can be adjusted to increase or decrease a mode
frequency, or dampen, or substantially attenuate a selected mode
frequency.
[0180] Although the method 2000 is described with reference to
measured values, in some examples, computer simulations using
finite element analysis or other modeling methods can be used.
[0181] Representative data is illustrated in FIGS. 21A-21B. In this
example, a driver type test club head (noted as #2 in the following
table) with a composite striking plate formed of about 24 layers
having an estimated COR of 0.835 and a CT of 269 .mu.s was used to
strike a golf ball with a club head speed of about 120 mph.
Referring to FIG. 21A, acoustic signal amplitude is displayed as a
function of time and frequency. For convenience, signal amplitudes
are generally color coded in such plots. In FIG. 21A, selected
relatively large amplitudes and relatively small amplitudes are
noted. Acoustic signal production in response to impact is
particularly apparent at times less than about 10-20 ms, with
substantial amplitudes persisting at some frequencies for up to
about 80 ms. FIG. 21B illustrates vibrational amplitude of the club
head striking face at 2120, a club head crown at 2122, and a club
head sole at 2124 at a selected frequency of about 3.84 kHz. Thus,
this frequency corresponds primarily to a vibrational mode of the
striking face and to a lesser extent, the crown. The frequency
response data is obtained by using a laser vibrometer and an impact
hammer at various locations on the club.
[0182] Driver type test club head #2 in Table 1 below includes a
significantly large face area of about 6978 mm.sup.2, a volume of
about 460 cc and a head mass of about 203 g. It should be noted
that driver type test club heads #2, #3, #5, and #6 in Table 1
below are exemplary embodiments of the invention and incorporate a
composite type face insert illustrated at least in FIG. 1 and
described in detail above. However, the face size of club heads #2,
#3, #5, and #6 are significantly larger than previously known
composite face drivers. Because the face size is significantly
larger, the sound of the club heads have achieved unique sound
qualities as described herein. Club heads #1 and #4 are titanium
face drivers provided for comparison purposes with the exemplary
embodiments of the present invention having a composite face
insert.
[0183] The table below lists measured lowest order striking surface
(face) mode frequencies for a variety of driver type club heads.
The damping constant provided in Table 1 is measured using ME'scope
VES.TM. (Visual Engineering Series) software from Vibrant
Technology Inc. version 5.1.2010.0709. The damping constant of club
heads #2, #3, #5, #6, and #7 are at least greater than 0.232 due to
the composite face providing a damping effect on a fully metallic
body, crown, and sole construction. The damping constant for the
composite face clubs range from 0.27 to 0.462 within these
examples. The damping constant can be between about 0.25 or 0.3 to
about 0.5 or 0.6 for a composite face insert club construction with
a metallic body, crown, and sole. The damping increase is primarily
due to the composite face construction in club heads 2, #3, #5, #6,
and #7. In contrast, club head #1 illustrates a titanium face club
head of similar face size and volume but having a significantly
reduced amount of damping at 0.232 due to the titanium face
construction. In addition, club head #4 appears to have an
increased damping constant of 0.639 due to the composite crown
construction alone. The damping constant of club head #4 is not
increased due to a composite face insert. In some cases, the club
heads are provided for acoustic testing only, and do not correspond
to USGA rules compliant clubs.
TABLE-US-00001 TABLE 1 Comparison of Composite Face Clubs and
Titanium Face Clubs Face CT Freq. Damp. Club No. Club Description
COR (.mu.s) (Hz) Const. Comments 1 Ti Striking Plate 0.846 294 3140
0.232 A008 2 Composite 0.835 269 3839 0.405 A013 Striking Plate 3
Composite 0.813 217 3870 0.462 A013/Ti Striking Plate with Ti Cap 4
Production Club 0.817 228 3930 .639 1.84 kHz sole mode Comparison
with Ti Striking 2.55 kHz crown mode Club Plate 5 Composite .822
242 4240 .34 A016 Striking Plate 6 Composite .816 233 4610 .27 A018
Striking Plate 7 Composite 0.82 237 4480 .32 A019/Ti Striking Plate
with Ti Cap
[0184] Representative data for club head #1 of the table above is
illustrated in FIGS. 22A-22B. In this example, a driver type test
club head with a titanium striking plate having an estimated COR of
0.846 and a CT of 294 .mu.s was used to strike a golf ball with a
club head speed of about 120 mph. The club head #1 has been
manufactured with a face area of 6978 mm.sup.2 and a volume of
about 460 cc for comparison purposes with club head #2 and #3. As
mentioned above, club heads #2 and #3 have a composite face insert
while the club head #1 has a titanium face with no composite
material in the face area. Because the face area and volume between
club head #1, #2, and #3 are similar, the loudness and frequency of
the clubs can be compared between composite face clubs and titanium
face clubs while controlling for the face area and volume
variables.
[0185] Referring to FIG. 22A, acoustic signal amplitude is
displayed as a function of time and frequency. In FIG. 22A,
selected relatively large amplitudes and relatively small
amplitudes are noted. Acoustic signal production in response to
impact is particularly apparent at times less than about 10-20 ms,
with substantial amplitudes persisting at some frequencies for up
to about 80 ms. FIG. 22B illustrates vibrational amplitude of the
club head striking face at 2220, a club head crown at 2222, and a
club head sole at 2224 at a selected frequency of about 3.13 kHz.
Thus, this frequency corresponds primarily to a vibrational mode of
the striking face and to a lesser extent, the Crown.
[0186] FIG. 22C illustrates relative acoustic amplitude as a
function of frequency associated with club #1 for ball strikes by
two players (referred to herein for convenience as "Player A" and
"Player B") with different swing speeds. (The "Player A` driver
swing speed is about 110 mph, with the "Player B" swing speed is
about 100 mph). FIGS. 22D-22E are graphs illustrating loudness
(sones) and acoustic amplitude (dB) as a function of time for the
two different players. For reference, a sound level of about 140 dB
corresponds to the sound of a rifle shot at a distance of 1 m, 130
dB is a level associated with hearing damage, and 120 dB is a pain
threshold. The sone is equivalent to 40 phons, which is defined as
the loudness level of a 1 kHz tone at 40 dB SPL (sound pressure
level).
[0187] The loudness (sones), sound power (watts) and acoustic
amplitude (dB) data described throughout the present application is
obtained through a specific test procedure. The loudness and
amplitude are measured using a microphone positioned at exactly 64
inches directly above the ball at impact as measured from the outer
surface of the ball to the outer surface of the microphone's sound
recording portion. The microphone used in the test procedure is a
G.R.A.S. Sound and Vibration pre-polarized microphone type 40AE.
The microphone was connected to a Bruel & Kjaer Pulse.TM. noise
and vibration analysis system (model 3160-B-140). The furthest
distance of any impact location away from the center-face of the
club was 11 mm as measured from the center face to the center point
of the impact location. Post-processing of the recorded data was
done using the Pulse.TM. Sound Quality software from Bruel &
Kjaer.
[0188] Data for additional club heads are provided in additional
figures. FIG. 23A is a plot of acoustic signal amplitude as a
function of time and frequency for club head #3 having a composite
face with a titanium cap layer as described in U.S. patent
application Ser. No. 11/960,609, filed Dec. 19, 2007, which is
incorporated herein by reference in its entirety. Club head #3 also
has a measured face area of about 6978 mm.sup.2, a volume of about
460 cc, and a mass of about 203 g. Club head #3 is virtually
identical to club head #2 except for the addition of the titanium
cap layer as described above. FIG. 23B illustrates relative
acoustic amplitude as a function of frequency associated with club
#3 (A013/Ti) for ball strikes by two players with different swing
speeds. FIGS. 23C-23D are graphs illustrating loudness (sones) and
acoustic amplitude (dB) as a function of time for the two different
players.
[0189] FIGS. 24A-24D illustrate acoustic properties of production
club head #4 that has a conventional titanium face. Club head #4 is
a comparison club that does not have a composite type club face.
The volume of club head #4 is about 446 cc and the estimated face
area is about 5229 mm.sup.2. Club head #4 has a mass of about 207
g. Club head #4 is unique in that it is the only club head provided
with a composite crown construction. This composite crown
construction may increase the amount of damping upon impact even
though the club face is a titanium construction. FIGS. 24B-24D
illustrate vibrational amplitudes at frequencies of about 1.84 kHz,
2.59 kHz, and 3.93 kHz, respectively, corresponding to a sole mode,
a crown mode, and a striking face mode. FIG. 24E illustrates
relative acoustic amplitude as a function of frequency associated
with club #4 for ball strikes by two players with different swing
speeds. FIGS. 24F-24G are graphs illustrating loudness (sones) and
acoustic amplitude (dB) as a function of time for the two different
players.
[0190] FIG. 25A illustrates acoustic properties of club head #5
that has a composite striking plate. Club head #5 has an estimated
face area of about 5236 mm.sup.2 and a volume of about 448 cc. The
head mass of club head #5 is about 203 g. A lowest order striking
face acoustic mode is at a frequency of about 4.24 kHz. Lower order
modes that appear in FIG. 25A correspond to modes associated with
other parts of the club head such as the crown or the sole. FIG.
25B illustrates relative acoustic amplitude as a function of
frequency associated with club #5 for ball strikes by two players
with different swing speeds. FIGS. 25C-25D are graphs illustrating
loudness (sones) and acoustic amplitude (dB) as a function of time
for the two different players.
[0191] FIG. 26 illustrates acoustic properties of club head #6 that
has a composite striking plate. Club head #6 has a face area of
about 5257 mm.sup.2, a volume of about 454 cc and a mass of about
203 g. A lowest order striking face acoustic mode is at a frequency
of about 4.61 kHz. Lower order modes that appear in FIG. 26
correspond to modes associated with other parts of the club head
such as the crown or the sole
[0192] FIG. 27 illustrates acoustic properties of club head #7 that
has a composite striking plate. Club head #7 has a face area of
about 5715 mm.sup.2, a volume of about 459 cc and a head mass of
about 203 g. Club head #7 also includes a titanium cap layer as
described in U.S. patent application Ser. No. 11/960,609, filed
Dec. 19, 2007, which is incorporated herein by reference in its
entirety. A lowest order striking face acoustic mode is at a
frequency of about 4.48 kHz. Lower order modes that appear in FIG.
27 correspond to modes associated with other parts of the club head
such as the crown or the sole.
[0193] FIGS. 28A-28B illustrate sound levels in sones and
A-weighted sound pressure, respectively, for ball strikes with a
plurality of club heads. As shown in FIGS. 28A and 28B, the Club
numbers shown in the x-axis correspond to the club numbers shown in
Table 1 shown above. In some cases, multiple prototypes with minor
variations but similar overall parameters were tested as shown. For
example, club head #2 from Table 1 was tested for loudness and
sound pressure levels in four distinct exemplary heads, club #2-1,
club #2-2, club #2-3, and club #2-4. The "-1 . . . -4" designation
indicates for separate test clubs having the same overall
construction and composite face type club head with potentially
minor modifications to the construction and varying manufacturing
tolerances.
[0194] FIGS. 28A and 28B also show an additional "competitor club"
which includes a fully titanium face construction but has a
composite crown similar to the construction of comparison club head
#4. Club head #4 and the "competitor club" shown in FIGS. 28A and
28B do not have a composite face insert.
[0195] As shown in FIG. 28A, Ti strike plates produce sound levels
greater than 225 sones. FIG. 28A also illustrates the striking
difference between loudness levels between a titanium face driver,
a composite face driver, an a composite face driver with a thin
titanium exterior cap. It should be noted that all the composite
face drivers (without a titanium cap) tested fall below the 225
sones loudness level. For example, club heads #2, #5, and #6 all
fall below the 225 sones level irrespective of club head speed (the
distinction between Player A and Player B). Club head #3, which has
a titanium cap, exceeds the sones limit of 225 slightly when struck
at a higher swing speed. However, all composite face club heads
(irrespective of whether a titanium cap is present) are below 237
sones and below 240 sones. In other words, club head #2, #3, #5,
#6, and #7 all fall below 237 sones and below 240 sones regardless
of the two player swing speeds provided and regardless of the
presence of a titanium cap construction. For comparison, it is
noted that all club heads tested having a fully titanium face have
a loudness of greater than 240 sones.
[0196] As shown in FIG. 28B, A-weighted sound pressures for clubs
with Ti striking plates exceed 5 Pa. Sound levels and A-weighted
sound pressures less than these values tend to produce satisfactory
sounds. It should be noted that all the composite face insert club
heads fall below the 5 Pa A-weighted sound pressure level except
club head #7. However, club head #7 includes a titanium cap layer
and this feature may explain why the A-weighted pressure data is
slightly higher for this club. All the composite face clubs
including club head #2, #3, #5, #6, and #7 all fall below an
A-weighted sound pressure level of about 5.6 Pa regardless of the
two types of swing speeds and regardless of whether a titanium cap
is present. For comparison, it is noted that all club heads tested
having a fully titanium face further have an A-weighted sound
pressure level that exceeds 5.6 Pa.
[0197] All the club head samples listed in FIGS. 28A and 28B have
been measured and are represented as data points in FIGS. 29-32.
FIGS. 29, 31, and 32 provide data points for loudness and
non-weighted sound measurements for the club head samples when
struck by Player A only (corresponding to a swing speed of about
110 mph), for ease of illustration.
[0198] FIG. 29 illustrates a plot of loudness (sones) on the y-axis
and face size (mm.sup.2) on the x-axis. As noted above, the
loudness for the titanium face drivers are clearly much louder than
the composite face insert drivers. Also, the loudness of the
titanium drivers appear to increase as a function of the face size
(face size as measured according to the procedure described below).
Based on the sample composite face insert drivers tested, there
also appears to be a trend of increased loudness as the face size
increases. However, the sample club heads with a composite face
insert (regardless of the presence of a Ti cap) are about 50 sones
less when compared to a titanium face head construction having the
same face size. In some embodiments, the composite face insert
construction is at least 45 sones, 35 sones, 25 sones, or 15 sones
less than a comparable titanium face club.
[0199] FIG. 29 further illustrates an expression to define a zone
of potential composite face insert embodiments. A linear boundary
expression described as Equation 1 is shown below:
y=0.0267x+81.667 Eq. 2
[0200] In Equation 2, y is the sones variable and x is the face
size variable. Equation 2 defines an upper limit of a primary
composite face insert zone. The primary composite face insert zone
extends between a face size of 5,000 mm.sup.2 to 8000 mm.sup.2 on
the x-axis and extends between about 175 sones up to the boundary
of Equation 2 described above on the y-axis.
[0201] FIG. 29 also illustrates a secondary composite face insert
zone that extends between a face size of 5,000 mm.sup.2 to 7,000
mm.sup.2 on the x-axis and extends between 175 sones up to the
boundary of Equation 2 described above on the y-axis. A narrower
composite face insert zone can also be defined such as a zone
having a y-axis limit between 175 sones up to the boundary of
Equation 2 and a x-axis limit between a face size of 5,000 mm.sup.2
to 6,000 mm.sup.2, 5,500 mm.sup.2 to 7,000 mm.sup.2, 6,000 mm.sup.2
to 7,000 mm.sup.2, or 6,500 mm.sup.2 to 7,000 mm.sup.2. In Equation
2, it should be noted that the slope value is a positive number
providing a positively sloped upper limit.
[0202] FIG. 30 illustrates a comparison between face frequency and
face size. Because the composite face is lighter than an ordinary
titanium face, the face frequency is higher for a composite face.
FIG. 30 illustrates a linear boundary equation defined by Equation
3 shown below:
y=-0.44x+6300 Eq. 3
[0203] In Equation 3, the y variable is the primary face frequency
mode of the face after an impact force and the x variable is the
face size (mm.sup.2). In Equation 3, the slope value is negative.
As the face size of a club is increased, the frequency appears to
decrease as well.
[0204] As previously discussed, the composite face clubs all fall
under 237 sones when impacted at center face. In addition to a low
loudness characteristic, the composite face clubs generally have a
face frequency greater than 3,800 Hz. When compared with titanium
face clubs of similar face size that are less than 5,500 mm.sup.2
in FIG. 30, the composite face clubs are at least 200 Hz, 100 Hz,
or 50 Hz higher. When compared with titanium face clubs of similar
face size that are greater than 6,000 mm.sup.2, the composite face
clubs are at least 600 Hz, 500 Hz, 400 Hz, 300 Hz, or 200 Hz
higher. For composite face clubs having a face size less than 5,500
mm.sup.2, the face frequency values ranged from about 4200 Hz to
about 4625 Hz. For composite face clubs having a face size greater
than 6,000 mm.sup.2, the face frequency values ranged from about
3,800 Hz to about 4,500 Hz.
[0205] Equation 3 defines an lower limit of a primary composite
face insert zone. The primary composite face insert zone extends
between a face size of 5,000 mm.sup.2 to 8000 mm.sup.2 on the
x-axis and extends between about 4,800 Hz down to the boundary of
Equation 3 described above on the y-axis.
[0206] FIG. 30 also illustrates a secondary composite face insert
zone that extends between a face size of 5,000 mm.sup.2 to 7,000
mm.sup.2 on the x-axis and extends between 4,700 Hz down to the
boundary of Equation 3 described above on the y-axis. A narrower
composite face insert zone can also be defined such as a zone
having a y-axis limit between 4,600 Hz down to the boundary of
Equation 3 and a x-axis limit between a face size of 5,000 mm.sup.2
to 6,000 mm.sup.2, 5,500 mm.sup.2 to 7,000 mm.sup.2, 6,000 mm.sup.2
to 7,000 mm.sup.2, or 6,500 mm.sup.2 to 7,000 mm.sup.2.
[0207] FIG. 31 illustrates a comparison between a sound pressure
level peak un-weighted signal (dB) at impact (by player A) with the
club head face size. In general, the composite face club heads have
a much lower sound pressure level than metallic clubs having a
metallic crown. The data point labeled 3100 in FIG. 31 is a
titanium face driver having a composite crown associated with club
head #4 in Table 1. Because of the dampening effect of the
composite crown, the comparison club head appears to have a lower
than usual sound pressure level. However, the dampening provided to
lower the sound pressure level is not created by the face. The
composite face insert club heads that are shown provide a dampening
of sound pressure levels primarily created via the composite face
while the body material and crown material is a metallic material
in such club heads.
[0208] FIG. 31 illustrates two linear boundary equations defined by
Equations 4 and 5 shown below:
y=0.0005x+110 Eq. 4
y=0.0005x+108.5 Eq. 5
[0209] The first proposed limit is Equation 4 and the second
proposed limit is Equation 5. In Equations 4 and 5, the y variable
is the sound pressure level at impact (by Player A) and the x
variable is the face size (mm.sup.2). In Equations 4 and 5, the
slope value is positive. As the face size of a club is increased,
the sound pressure level appears to increase as well.
[0210] The composite face clubs all fall under 113 dB when struck.
When compared with titanium face clubs of similar face size that
are greater than 6,000 mm.sup.2, the composite face clubs are at
least 3 dB, 2.5 dB, 2 dB, 1.5 dB, or 1 dB lower. For composite face
clubs (without a titanium cap) having a face size less than 5,500
mm.sup.2, the sound pressure values ranged from about 109 dB to
about 112 dB. For composite face clubs (without a titanium cap)
having a face size greater than 6,000 mm.sup.2, the sound pressure
values ranged from about 109 dB to about 112 dB. An outlier data
point 3102 occurring between 112 dB and 113 dB, at a face size
between 5,500 mm.sup.2 and 6,000 mm.sup.2, is associated with a
composite face insert having a titanium cap layer which is within
the scope of this invention. It should be noted that the club head
associated with data point 3102 is slightly higher in sound
pressure levels than other composite face drivers without a
titanium cap, but would still be well below the sound pressure
levels found in ordinary titanium drivers (without a composite
crown).
[0211] Equations 4 and 5 define an upper limit of a number of
composite face insert zone. The primary composite face insert zone
(including Ti cap embodiments) extends between a face size of 5,000
mm.sup.2 to 8000 mm.sup.2 on the x-axis and extends between about
109 dB up to the boundary of Equation 4 on the y-axis. An
alternative primary composite face insert zone (excluding Ti cap
embodiments) extends between a face size of 5,000 mm.sup.2 to 8000
mm.sup.2 on the x-axis and extends between about 109 dB up to the
boundary of Equation 5 on the y-axis.
[0212] FIG. 31 also illustrates a secondary composite face insert
zone (including Ti cap embodiments) that extends between a face
size of 5,000 mm.sup.2 to 7,000 mm.sup.2 on the x-axis and extends
between 109 dB up to the boundary of Equation 4 described above on
the y-axis. An alternative second composite face insert zone
(including Ti cap embodiments) extends between a face size of 5,000
mm.sup.2 to 7,000 mm.sup.2 on the x-axis and extends between 109 dB
up to the boundary of Equation 5.
[0213] A narrower composite face insert zone can also be defined
such as a zone having a y-axis limit between 109 dB up to the
boundary of Equation 4 or 5 and a x-axis limit between a face size
of 5,000 mm.sup.2 to 6,000 mm.sup.2, 5,500 mm.sup.2 to 7,000
mm.sup.2, 6,000 mm.sup.2 to 7,000 mm.sup.2, or 6,500 mm.sup.2 to
7,000 mm.sup.2.
[0214] FIG. 32 illustrates a comparison between a sound pressure
level peak un-weighted signal (dB) at impact (by Player A) with the
club head face size. In general, the composite face club heads have
a much lower sound pressure level than metallic clubs having a
metallic crown. Again, club head #4 labeled 3200 in FIG. 32 is a
titanium face driver having a composite crown. As mentioned above,
because of the dampening effect of the composite crown, the
comparison club head appears to have a lower than usual sound
pressure level. However, the dampening provided to lower the sound
pressure level is not created by the face in the club head
associated with this data point 3200.
[0215] A primary composite face insert zone extends between
frequency of 3,800 Hz to 4,800 Hz on the x-axis and extends between
about 105 dB up to 114 dB on the y-axis. An alternative primary
composite face insert zone (that does not include composite crown
clubs) extends between a frequency of 4,000 Hz to 4,800 Hz on the
x-axis and extends between about 105 dB up to 114 dB on the
y-axis.
[0216] FIG. 32 also illustrates a secondary composite face insert
zone that extends between a frequency of 3,800 Hz to 4,700 Hz on
the x-axis and extends between 109 dB up to 112 dB on the y-axis.
An alternative second composite face insert zone extends between a
frequency of 4,000 Hz to 4,700 Hz on the x-axis and extends between
109 dB up to 112 dB on the y-axis.
[0217] A narrower composite face insert zone can also be defined
such as a zone having a y-axis limit between 109 dB up to 110 dB or
111 dB and a x-axis limit between a frequency of 3,800 Hz to 4,000
Hz, 4,000 Hz to 4,400 Hz, 4,400 Hz to 4,600 Hz, or 4,600 Hz to
4,800 Hz. All the composite face club heads tested in FIG. 32 have
face size greater than at least 5,000 mm.sup.2.
[0218] Thus, by varying striking face density, elastic constant,
thickness, CT, COR, or other striking face property a suitable club
head sound can be achieved. In some examples, club head sound
levels in response to ball strikes at club head speeds of between
100-120 mph are less that 5 Pa (A-weighted) or less than 225 sones
are suitable. Face resonance frequencies of 3.9 kHz, 4.2 kHz, or
4.4 kHz or greater are associated with suitable "pleasing" shot
sounds. In some examples, a face thickness can be varied or a face
thickness can be modified by local thinning or thickening at or
near acoustic resonance nodes and/or antinodes.
[0219] While the above discussion is generally directed to
improving sound characteristics (i.e., providing more pleasant
sounds), in other examples club heads can be configured to produce
unpleasant sounds or have other sound characteristics. Sound
characteristics can be adjusted to provide a more aggressive or
less pleasing sound by, for example, providing face resonances at
frequencies less than about 3.5 kHz and/or amplitudes greater than
about 225 sones or A-weighted pressures of greater than about 5 Pa.
It will be appreciated that the examples disclosed herein are not
to be taken as limiting the scope of the disclosure, and I claim
all that is encompassed by the appended claims.
[0220] In certain embodiments, the total mass of the golf club head
is between 185 g and 215 g or between 190 g and 210 or between
about 194 g and 205 g. In similar embodiments, the volume of the
golf club head as measured according to the USGA rules is between
390 cc and about 475 cc, or between about 410 cc and 470 cc, or
between about 400 cc to about 475 cc, or greater than 400 cc. In
certain embodiments, the coefficient of restitution is greater than
0.80 or 0.81 or between about 0.81 and 0.83 as measured according
to the USGA rules of golf. Furthermore, the COR in the club heads
of the present invention are between 0.80 and 0.81, or between 0.81
and 0.82, or between 0.82 and 0.83, or between 0.83 and 0.84. In
some cases, a COR is achieved between 0.80 and 0.84. In addition,
in some embodiments, the characteristic time is greater than 230
.mu.s or 220 .mu.s or between about 230 .mu.s and 257 .mu.s as
measured according to the USGA rules.
[0221] The golf club head has a head origin defined as a position
on the face plane at a geometric center of the face. The head
origin includes an x-axis tangential to the face and is generally
parallel to the ground when the head is in an address position. At
the address position, a positive x-axis extends towards the heel
portion and a y-axis extends perpendicular to the x-axis and is
generally parallel to the ground. A positive y-axis extends from
the face and through the rearward portion of the body and a z-axis
extends perpendicular to the ground, to the x-axis and to the
y-axis when the head is ideally positioned. Furthermore, a positive
z-axis extends from the origin and generally upward.
[0222] In the metal-wood embodiments described herein, the "face
size" or "face area" or "striking surface area" of "face size
surface area" is defined according to a specific procedure
described herein. A front wall extended surface 3306 is first
defined which is the external face surface that is extended outward
(extrapolated) using the average bulge radius (heel-to-toe) and
average roll radius (crown-to-sole). The bulge radius is calculated
using five equidistant points of measurement fitted across a 2.5
inch segment along the surface of the face as projected from the
x-axis (symmetric about the center point). The roll radius is
calculated by three equidistant points fitted across a 1.5 inch
segment along the surface of the face as projected from the y-axis
(also symmetric about the center point).
[0223] The front wall extended surface 3306 is then offset by a
distance of 0.5 mm towards the center of the head in a direction
along an axis that is parallel to the face surface normal vector at
the center of the face. The center of the face is defined according
to USGA "Procedure for Measuring the Flexibility of a Golf
Clubhead", Revision 2.0, Mar. 25, 2005.
[0224] FIG. 33A illustrates the front wall extended surface 3306
after it has been offset by the 0.5 mm distance. A face front wall
profile shape curve 3308 is defined at the intersection of the
external surface of the head 3300 with the offset front wall
extended surface 3306. A cylindrical section 3302 is also defined
having a 30 mm diameter cylindrical surface that is co-axial with
the shaft or hosel axis. The intersection of the face front wall
profile shape curve 3308 with the cylindrical section 3302 occurs
at a first intersection point 3314. Futthermore, a sectioning line
3304 is drawn from the first intersection point 3314 along the
surface of the club in a direction normal to the hosel axis 3318.
The section line 3304 then intersects a second intersection point
3320 that represents the intersection of the front wall profile
shape curve 3308 with the section line 3304 as it is extended in a
direction normal to the hosel axis. A hosel trimmed front wall
profile shape curve 3322 is then created as seen in FIG. 33B. The
hosel trimmed front wall profile shape curve 3322 is defined by a
portion of the front wall profile shape curve 3308 and the section
line 3304 as it extends between the first intersection point 3314
and the second intersection point 3320. The hosel trimmed front
wall profile shape curve 3322 contains a first area 3310.
[0225] A front wall plane is then defined as a plane which is
tangent to the face surface at the geometric center of the face
using the method defined in Section 6.1 of the USGA Procedure for
Measuring the Flexibility of a Golf Clubhead (Revision 2.0 Mar. 25,
2005).
[0226] The hosel trimmed front wall profile shape curve 3322 is
then projected onto the front wall plane, which is a two
dimensional surface plane. Subsequently, the projection of the
hosel trimmed front wall profile shape curve 3322 on the front wall
plane is modified to find the final face area as defined herein.
Specifically, in the projection plane at the first intersection
point 3314 and the second intersection point 3320, a tangent line
3330,3324 is drawing tangent to the hosel trimmed front wall
profile shape curve 3322 (as projected on the front plane) at the
intersection points 3314,3320 until the tangent lines 3330,3324
intersect each other at a vertex 3326, as seen in FIG. 33C. These
two tangent lines 3330,3324 and the remaining hosel trimmed front
wall profile shape curve 3322 together define the "face size" or
"face size surface area" as discussed above. In other words, the
two tangent lines 3330,3324 create a second area 3328 which is
added to the first area 3310 (as projected on a plane) to create
the final face size or face size surface area, as seen in FIG.
33C.
[0227] In certain embodiments, the striking surface has a surface
area between about 4,500 mm.sup.2 and 6,200 mm.sup.2 and, in
certain preferred embodiments, the striking surface is at least
about 5,000 mm.sup.2 or between about 5,300 mm.sup.2 and 6,900
mm.sup.2 or between about 5,000 mm.sup.2 and 7,000 mm.sup.2. In
some embodiments, the face size surface area includes a metallic
material and a composite material which are both located on the
front portion of the club head and are within a face size surface
area region.
[0228] In order to achieve the desired face size, mass is removed
from the crown material so that the crown material is between about
0.4 mm and 0.8 mm or less than 0.7 mm over at least 50% of the
crown surface area.
[0229] FIG. 34A illustrates a wood-type (e.g., driver or fairway
wood) golf club head from a top view of the club head 3400 with a
face insert, according to another embodiment. The club head 3400
includes a front portion 3402, a back portion 3404, a heel portion
3418, a toe portion 3410, a striking surface 3416, a hosel 3412,
and a crown portion 3406. The club head 3400 also includes a face
angle 3401 when at an address position. A hosel plane 3403 is shown
which contains a hosel axis 3405. For ease of illustration,
striking face score lines are excluded from this view.
[0230] FIG. 34B shows the club head 3400 from a front view at an
address position including a hollow body having a crown portion
3406, a sole portion 3408, and a front portion 3402. The club head
3400 also includes a hosel 3412 which defines a hosel bore defining
a hosel axis 3405 and is connected with the hollow body. The hollow
body further includes a heel portion 3418 and a toe portion 3410. A
striking surface 3416 is located on the front portion 3402 of the
golf club head 3400 having score lines or markings 3420. In some
embodiments, the striking surface 3416 can include a bulge and roll
curvature or a face insert. In the embodiments of the present
invention, the striking surface 3416 is at least partially made of
a composite material as described in U.S. patent application Ser.
Nos. 10/442,348 (now U.S. Pat. No. 7,267,620), 10/831,496 (now U.S.
Pat. No. 7,140,974), 11/642,310, 11/825,138, 11/998,436,
11/895,195, 11/823,638, 12/004,386, 12/004,387, 11/960,609,
11/960,610, and 12/156,947, which are incorporated herein by
reference in their entirety. The composite material can be
manufactured according to the methods described at least in U.S.
patent application Ser. No. 11/825,138. A polymer coating is be
applied to the composite material as shown in FIGS. 34A-E.
[0231] In other embodiments, the striking surface 3416 is at least
partially made from a metal alloy (e.g., titanium, steel, aluminum,
and/or magnesium), ceramic material, or a combination of composite,
polymer, metal alloy, and/or ceramic materials. Moreover, the
striking face 3416 can be a striking plate having a variable
thickness as described in U.S. Pat. Nos. 6,997,820, 6,800,038,
6,824,475, and 7,066,832 which are incorporated herein by reference
in their entirety. For example, the face insert can have a total
thickness that is within a range of about 1 mm to about 8 mm. The
face insert can be made of prepreg plies having a fiber areal
weight of less than 100 g/m.sup.2.
[0232] FIG. 34B also shows an inset distance 3442 that defines a
distance between the perimeter of the face insert and the perimeter
of the striking surface 3416. The inset distance 3442 may be less
than about 13 mm and greater than 1 mm, less than about 8 mm and
greater than 6 mm.
[0233] FIGS. 34B and 34C generally show a club head origin
coordinate system being provided such that the location of various
features of the club head (including, e.g., a club head CG) can be
determined. In FIGS. 34B and 34C, a club head origin point 3422 is
represented on the club head 3400. The club head origin point 3422
is positioned at the ideal impact location which can be a geometric
center of the striking surface 3416.
[0234] The head origin coordinate system is defined with respect to
the head origin point 3422 and includes a Z-axis 3424, an X-axis
3426, and a Y-axis 3428. The Z-axis 3424 extends through the head
origin point 3422 in a generally vertical direction relative the
ground 3401 when the club head 3400 is at an address position
(although the Z-axis 3424, X-axis 3426, and Y-axis 3428 are
independent of club head 3400 orientation). Furthermore, the Z-axis
3424 extends in a positive direction from the origin point 3422 in
an upward direction.
[0235] The X-axis 3426 extends through the head origin point 3422
in a toe-to-heel direction substantially parallel or tangential to
the striking surface 116 at the origin point 3422. The X-axis 3426
extends in a positive direction from the origin point 3422 to the
heel 3418 of the club head 3400 and is perpendicular to the Z-axis
3424 and Y-axis 3428.
[0236] The Y-axis 3428 extends through the head origin point 3422
in a front-to-back direction and is generally perpendicular to the
X-axis 3426 and Z-axis 3424. The Y-axis 3428 extends in a positive
direction from the origin point 3422 towards the rear portion or
back portion 3404 of the club head 3400.
[0237] Referring to FIGS. 34B and 34C, the golf club heads
described herein each have a maximum club head height (H,
top-bottom), width (W, heel-toe) and depth (D, front-back). The
maximum height, H, is defined as the distance between the lowest
and highest points on the outer surface of the golf club head body
measured along an axis parallel to the origin Z-axis 3424 when the
club head is at a proper address position. The maximum depth, D, is
defined as the distance between the forward-most and rearward-most
points on the surface of the body measured along an axis parallel
to the origin Y-axis 3428 when the head is at a proper address
position. The maximum width, W, is defined as the distance between
the farthest distal toe point and closest proximal heel point on
the surface of the body measured along an axis parallel to the
origin X-axis 3426 when the head is at a proper address position.
FIG. 34B further shows a lie angle 3434 between a hosel axis 3424
and a level ground surface 3401 when the head 3400 is at a proper
address position. FIG. 34C shows the striking surface 3416 having a
face normal vector 3430 that forms a face loft angle 3414. The face
normal vector 3430 intersects the origin point 3422 and extends in
a positive direction away from the club head body. The face normal
vector 3430 is perpendicular to a plane that is tangent to the
origin point 3422.
[0238] The height, H, width, W, and depth D of the club head in the
embodiments herein are measured according to the United States Golf
Association "Procedure for Measuring the Club Head Size of Wood
Clubs" revision 1.0 and Rules of Golf, Appendix II(4)(b)(i).
[0239] Golf club head moments of inertia are defined about three
axes extending through the golf club head CG 3432 including: a CG
z-axis extending through the CG 3432 in a generally vertical
direction relative to the ground 3401 when the club head 3400 is at
address position, a CG x-axis extending through the CG 132 in a
heel-to-toe direction generally parallel to the origin X-axis 3426
and generally perpendicular to the CG z-axis, and a CG y-axis
extending through the CG 3432 in a front-to-back direction and
generally perpendicular to the CG x-axis and the CG z-axis. The CG
x-axis and the CG y-axis both extend in a generally horizontal
direction relative to the ground 3401 when the club head 3400 is at
the address position. In other words, the CG x-axis and CG y-axis
lie in a plane parallel to the ground 3401. Specific CG location
values are discussed in further detail below with respect to
certain exemplary embodiments.
[0240] The moment of inertia about the golf club head CG x-axis is
calculated by the following equation:
I.sub.CG=.intg.(y.sup.2+z.sup.2)dm Eq. 6
[0241] In the above equation, y is the distance from a golf club
head CG xz-plane to an infinitesimal mass, dm, and z is the
distance from a golf club head CG xy-plane to the infinitesimal
mass, dm. The golf club head CG xz-plane is a plane defined by the
CG x-axis and the CG z-axis. The CG xy-plane is a plane defined by
the CG x-axis and the CG y-axis.
[0242] Moreover, a moment of inertia about the golf club head CG
z-axis is calculated by the following equation:
I.sub.CG=.intg.(x.sup.2+y.sup.2)dm Eq. 7
[0243] In the equation above, x is the distance from a golf club
head CG yz-plane to an infinitesimal mass dm and y is the distance
from the golf club head CG xz-plane to the infinitesimal mass dm.
The golf club head CG yz-plane is a plane defined by the CG y-axis
and the CG z-axis. Specific moment of inertia values for certain
exemplary embodiments are discussed further below.
[0244] FIG. 34D shows a sole view of an exemplary embodiment club
head 3400 including a front portion 3402, a rear portion 3404, a
heel portion 3418, a toe portion 3410, a crown portion 3406, and a
sole portion 3408. A movable weight 3436 is located within a weight
port 3438 in the heel portion 3418 of the sole 3408. The movable
weight 3436 increases the MOI of the club head while lowering the
CG location. In addition a badge 3440 is located on the sole
portion 3408 of the club head near the rear portion 3404 of the
club head. The badge 3440 contains identifying indicia such as the
club head name, for example.
[0245] FIG. 34E illustrates a cross-sectional profile view 3444 of
the golf club head taken along horizontal sectional lines 34E-34E
in FIG. 34B. The heel-side support structure 3448 includes a
non-undercut region 3456 within the heel-side region of the club
head. The heel-side rear support member 3452 is integral with the
internal hosel tube structure 3454. The outer surface of the
internal hosel tube structure 3454 directly connects to the
non-undercut region 3456. The non-undercut region 3456 extends
toward the face away from the outer surface of the internal hosel
tube structure 3454 to form the heel-side rear support member 3452.
In contrast, the toe-side support structure 3446 includes an
undercut region 3450 within the toe-side region of the club head.
As seen in FIG. 34E, the most aggressive undercut structure occurs
on the toe-side of the club head due to the fact that structural
failure is less likely to occur when a mishit occurs on the
toe-side of the club head.
[0246] FIG. 35 illustrates a golf club head 3500 sectional view
when taken along section lines 35-35 in FIG. 34A showing a rear
portion of the striking face and insert 3518, a toe portion 3534, a
heel portion 3536, a crown portion 3538, and a sole portion 3540.
The striking face includes a front opening 3530 having a face
insert support structure 3516 that includes a rear support member
3532. The face insert 3518 is attached at the front opening 3530
and thereby closes the front opening of the body when the club head
is fully assembled. The face insert 3518 has a face insert area
which is defined as the frontal surface area of the face insert
3518 when viewed from the front of the club head. In one
embodiment, the face insert 3518 has a variable thickness with a
thickest portion 3520 located near the geometric center of the face
insert 3518 and thinner face insert 3518 portions located near the
peripheral edges of the face insert 3518. The rear support member
3532 provides a ledge for which the face insert 3518 is
supported.
[0247] A toe undercut portion 3526,3524 is located toward the toe
portion 3534 of the golf club head 3500. A heel undercut portion
3514 is located toward the heel portion 3536. A crown non-undercut
portion 3522 is located toward a crown portion 3538 and a sole
non-undercut portion 3528 is located toward a sole portion
3540.
[0248] The toe undercut portion 3526,3524 extends from a crown-side
toe undercut portion 3524 to a sole-side toe undercut portion 3526.
In one embodiment, the heel undercut portion 3514 is located
primarily near the crown portion 3538 only as shown in FIG. 35.
However, in another embodiment, the heel undercut portion 3514 is
located near the crown portion 3538 and the sole portion 3540,
similar to the toe undercut portion 3526,3524.
[0249] FIG. 35 further illustrates a removable shaft system having
a ferrule 3502, a sleeve bore 3542 within a sleeve 3504. A shaft is
inserted into the sleeve bore 3542 and is mechanically secured
(includes adhesive bonding, threaded attachments, pin attachments
or other known mechanical connections) to the sleeve 3504. The
sleeve 3504 further includes an anti-rotation portion 3544 at a
distal tip of the sleeve 3504 and a threaded bore 3506 for
engagement with a screw 3510 or mechanical fastener that is
inserted into the sole opening 3512 of the club head 3500. In one
embodiment, the sole opening 3512 is directly adjacent to a
non-undercut portion 3528. The anti-rotation portion 3544 of the
sleeve 3504 engages with an anti-rotation collar 3508 which is
bonded or welded within the hosel bore or opening of the golf club
head 3500. The adjustable loft, lie, and face angle system is
described in U.S. patent application Ser. No. 12/687,003 (now U.S.
Pat. No. 8,303,431), which is incorporated by reference in its
entirety.
[0250] The embodiment shown in FIG. 35 includes an adjustable loft,
lie, or face angle system that is capable of adjusting the loft,
lie, or face angle either in combination with one another or
independently from one another. For example, a portion of the
sleeve 3504, the sleeve bore 3542, and the shaft collectively
define a longitudinal axis 3546 of the assembly. The hosel sleeve
is effective to support the shaft along the longitudinal axis 3546,
which is offset from a longitudinal axis 3548 of the interior hosel
tube bore by offset angle 3550. The sleeve can provide a single
offset angle that can be between 0 degrees and 4 degrees, in 0.25
degree increments. For example, the offset angle can be 1.0 degree,
1.25 degrees, 1.5 degrees, 1.75 degrees, 2.0 degrees, 2.25 degrees,
2.5 degrees, 2.75 degrees, or 3.0 degrees. The offset angle of the
embodiment shown in FIG. 35 is 1.5 degrees. The amount of offset
angle can have an impact on the face angle and loft of the golf
club head at impact and thus may impact sound. Thus, the club head
of FIG. 35 achieves desirably sound properties despite the offset
angle.
[0251] In certain embodiments, the face insert 3518 is adhesively
or mechanically attached to the face insert support structure 3516.
In one embodiment, an epoxy adhesive such as 3M.TM. Scotch-Weld.TM.
Epoxy Adhesive DP460 is utilized having a shore D hardness of about
75 to 84. In other embodiments, an epoxy adhesive such as 3M.TM.
Scotch-Weld.TM. Epoxy Adhesive DP420 is utilized to attach the face
insert 3518 to the support structure 3516. It is understood that
numerous equivalent adhesives can be used to attach the face insert
3518 to the support structure 3516.
[0252] With respect to the embodiment of FIGS. 34A-E and FIG. 35,
the overall club head weight is about 190 g to about 210 g or
between 180 g and 250 g. The club head of the embodiments described
herein can have a mass of about 200 g to about 210 g or about 190 g
to about 200 g. In certain embodiments, the total mass of the golf
club head is between 185 g and 215 g or between about 194 g and 205
g. Additional mass added by the undercut fill material, such as
titanium, will have an effect on moment of inertia and center of
gravity values as shown in Tables 2 and 3. Table 2 illustrates
exemplary MOI that can be achieved by the embodiments described
herein.
TABLE-US-00002 TABLE 2 I.sub.CGx I.sub.CGy I.sub.CGz (kg mm.sup.2)
(kg mm.sup.2) (kg mm.sup.2) 180 to 300 290 to 330 390 to 410 170 to
310 280 to 340 380 to 420 160 to 320 270 to 350 370 to 430
[0253] The embodiments described conform with the U.S.G.A. Rules of
Golf and in some examples the I.sub.CGz is less than 590 kgmm.sup.2
plus a test tolerance of 10 kgmm.sup.2. In similar embodiments, the
moment of inertia about the CG x-axis (toe to heel), the CG y-axis
(back to front), and CG z-axis (sole to crown) is defined. In
certain implementations, the club head can have a moment of inertia
about the CG z-axis, between about 450 kgmm.sup.2 and about 650
kgmm.sup.2, and a moment of inertia about the CG x-axis between
about 300 kgmm.sup.2 and about 500 kgmm.sup.2, and a moment of
inertia about the CG y-axis between about 300 kgmm.sup.2 and about
500 kgmm.sup.2.
[0254] Table 3 illustrates exemplary CG location coordinates with
respect to the origin point axes.
TABLE-US-00003 TABLE 3 CGX origin x-axis CGY origin y-axis CGZ
origin z-axis coordinate (mm) coordinate (mm) coordinate (mm) 2.8
to 4.5 27 to 32 -1 to -4 2.5 to 5.0 22 to 37 -0.5 to -5 2 to 6 20
to 40 1 to -8
[0255] The non-undercut regions of the face support area described
herein are a solid single piece casting that may have a negative
impact on CG location. However, the negative impact on CG location
is far outweighed by the durability benefits and performance
benefits, such as sound, achieved by having some regions of the
face support structure having an undercut while strategically
selecting other regions to be without an undercut (as measured
according to the methodology outlined above). In certain
embodiments, the CG x-axis coordinate is between approximately -5
mm and approximately 10 mm, a CG y-axis coordinate is between
approximately 20 mm and approximately 50 mm, and a CG z-axis
coordinate between approximately -10 mm and approximately 5 mm.
[0256] Furthermore, a significant advantage of the present
invention is that an adjustable shaft system that adjusts loft,
lie, or face angle is implemented in a single golf club head having
strategically placed non-undercut and undercut regions to ensure
durability while maintaining sound performance characteristics.
[0257] In similar embodiments, the volume of the golf club head as
measured according to the USGA rules is between 390 cc and about
475 cc, or between about 410 cc and 470 cc, or between about 400 cc
to about 475 cc, or greater than 400 cc. In certain embodiments,
the coefficient of restitution is greater than 0.80 or 0.81 or
between about 0.81 and 0.83 as measured according to the USGA rules
of golf. Furthermore, the COR in the club heads of the present
invention are between 0.80 and 0.81, or between 0.81 and 0.82, or
between 0.82 and 0.83, or between 0.83 and 0.85. In some cases, a
COR is achieved between 0.80 and 0.85. In addition, in some
embodiments, the characteristic time is greater than 230 .mu.s or
220 .mu.s or between about 230 .mu.s and 257 .mu.s as measured
according to the USGA rules. In one example of the golf club head
shown in FIGS. 34A-E and FIG. 35, a single tested club head had a
COR of 0.825 and a characteristic time of 233 .mu.s.
[0258] The face insert 3518 area and face size, as defined in the
above methodology, can be described in a face insert area to face
size ratio, as shown below in Equation 8:
Face Insert Area - to - Face Size Ratio = Face Insert Area Face
Size Ratio Eq . 8 ##EQU00001##
[0259] The face insert area to face size ratio needs to be greater
than about 0.65 and less than 1, greater than about 0.70 and less
than 1, or greater than about 0.75 and less than 1. The face insert
area to face size ratio is defined as the face insert area divided
by the face size according to the offset plane method described
above. In the embodiment shown in FIGS. 34A-E and FIG. 35, the face
insert is 4,654 mm.sup.2 and the face area is 5,678 mm.sup.2
thereby providing an exemplary ratio of 0.82.
[0260] FIGS. 36A-C relate to acoustic properties of the club head
construction shown in FIGS. 34A-E and FIG. 35. FIG. 36A is a plot
of acoustic signal amplitude (dB) as a function of frequency. In
this exemplary embodiment, the club head also has a measured face
area or face size of about 5678 mm.sup.2, a volume of about 448 cc,
and a mass of about 192 g. FIG. 36A illustrates relative acoustic
amplitude as a function of frequency for ball strikes by two
players with different swing speeds, as described above. FIGS.
36B-36C are graphs illustrating loudness (sones) and acoustic
amplitude (dB) as a function of time, respectively for the two
different players. In FIG. 36B, a peak loudness value of 219.99
sones is achieved by a player with a higher swing speed, as defined
above. A slower swing speed player achieves a peak loudness value
of 213.4 sones. In FIG. 36C, a peak amplitude of 111.81 dB is
achieved by a higher swing speed player compared to an amplitude of
110.22 dB for a slower swing speed player. The values achieved by
the embodiments of FIGS. 34A-E and FIG. 35 are consistent with the
results for amplitude and loudness of the previous embodiments
described above. However, the embodiment of FIGS. 34A-E and FIG. 35
implements an adjustable loft, lie, and face angle system and a
performance enhancing support member having undercut and
non-undercut regions while maintaining improved sound
characteristics.
[0261] FIG. 37 illustrates a golf club head cross-sectional view
3700 having a face insert 3734 that includes a composite layer 3706
having a side wall 3736 portion. A cover layer 3704 that is
attached to the composite layer 3706 and can include score lines
3738. In one embodiment, the cover layer 3704 can be a polymer
cover layer that attaches to the front surface of the composite
layer 3706. In another embodiment, the cover layer 3704 can be a
metallic titanium such as 6-4 titanium, 10-2-3 titanium, 15-3-3-3
titanium, 7-2 titanium, or commercially pure titanium. In certain
embodiments, the cover layer 3704 does not overlap with the side
wall 3736 of the composite layer 3706. The side wall 3736 engages
either directly or indirectly with a peripheral wall of the support
structure that receives the face insert 3734. In other embodiments,
the cover layer 3704 acts as a cap where a wrap-around portion of
the cover layer 3704 does overlap with the side wall 3736 of the
composite layer 3706.
[0262] FIG. 37 further shows a rear support member 3710, an apex
point 3714 on the interior surface contour 3712, an undercut nadir
3720, an interior body surface 3718, an interior surface contour
end point 3708, an outer body surface 3702, and a face curvature
3728 that matches the curvature of the golf club head striking face
at a given cross-section through the center of the face. For
example, if the cross-sectional view is taken through a vertical
plane containing the center of the face, the Z-axis origin, and
Y-axis origin, the face curvature 3728 would be the roll curvature
of the club head as measured according to the method outlined
below. Similarly, if the cross-sectional view is taken through a
horizontal plane containing the center of the face, the X-axis
origin, and Y-axis origin, the face curvature 3728 would be the
bulge curvature of the club head as measured according to the
method outlined below.
[0263] The method for determining the face curvature 3728 within
any cross-sectional plane through the face center consists of
calculating three equidistant points fitted across a 1.5 inch
curved segment along the surface of the face. The middle
equidistant point is located in the middle of the 1.5 inch segment.
The middle equidistant point is located at the face center location
and a face curvature line is fitted through the three equidistant
points. The face curvature described is a constant radius curvature
between the three equidistant points and cannot be an arbitrary
complex spline curvature.
[0264] FIG. 37 further shows an apex offset curvature 3724 that is
identical in orientation and curvature to the face curvature 3728.
However, the location of the apex offset curvature 3724 is offset
or spaced away from the face curvature 3728 along a face normal
vector 3730. The apex offset curvature 3724 is offset along the
face normal vector 3430 until the apex offset curvature 3724
becomes tangent to an apex point 3714 located on the interior
surface contour 3712. Similarly, a nadir offset curvature 3726 is
offset along the face normal vector 3430 by an offset distance. The
nadir offset curvature 3726 is tangent to the undercut nadir point
3720 as measured along the face normal vector 3430 axis. An
undercut distance 3722 is defined between the nadir offset
curvature 3726 and the apex offset curvature 3724 as defined along
the face normal vector axis 3430. If the undercut distance 3722 is
greater than zero (assuming a positive direction is along the face
normal vector pointing away from the club head as shown in FIG.
34C), then an undercut is deemed to exist within the
cross-sectional plane in question. In some embodiments, the
undercut distance 622 is between 0-1 mm, 1-2 mm, 2-3 mm, 4-5 mm,
0-15 mm, 0-10 mm, or between 0-20 mm. In contrast, if the undercut
distance 622 is non-existent, zero, or less (assuming a negative
direction is along the face normal vector pointing toward the
interior of the club head), then an undercut is deemed not to exist
within the cross-sectional plane in question. In some instances, an
undercut cannot be measured because no nadir point can be
identified and therefore the undercut distance is deemed to be
non-existent.
[0265] FIG. 37 further shows a nadir face normal axis 3730 that
passes through the nadir point 3720. The nadir face normal axis
3730 is parallel to the face normal vector 3430 but passes through
the nadir point 3720 of the undercut instead of the face center.
Likewise, an apex face normal axis 3732 passes through the apex
point 3714 and is parallel to both the face normal vector 3430 and
the nadir face normal axis 3730. An apex thickness 3716 is measured
along the apex face normal axis 3732. In one example, the apex
thickness is about 5.8 mm. In some embodiments, the apex thickness
is between 5 mm and 6 mm, between 4 mm and 7 mm, or between 3 mm
and 8 mm.
[0266] An undercut height 3744 is defined as the distance between
the apex face normal axis 3732 and the nadir face normal axis 3730
as measured along a direction perpendicular to both axis 3730,3732.
In some embodiments, the undercut height 3744 is between 0-1 mm,
1-2 mm, 2-3 mm, 4-5 mm, 1-15 mm, 1-10 mm, or between 0-20 mm.
[0267] FIG. 37 also shows an end point face normal axis 3740 that
passes through the interior surface contour end point 3708 and is
also parallel to the face normal vector 3430. The thickness of the
rear support member 3742 at the end point 3708 (i.e. end point
thickness) is measured along the end point face normal axis 3740.
In the embodiment shown, the end point thickness 3742 is less than
the apex thickness 3716. In one example, the end point thickness
3742 is about 1 mm. In some embodiments, the end point thickness
3742 is between 0.2 mm and 2 mm, or between 0.5 mm and 1.5 mm. FIG.
37 also shows a face insert depth 3746 which defines the recess
that receives the face insert 3734. The face insert depth 3746 and
the end point thickness 3742 define a face insert ratio shown below
in Equation 9 below:
Face Insert Ratio = Face Insert Depth End Point Thickness Eq . 9
##EQU00002##
[0268] In one embodiment, the face insert depth is about 4.5 mm and
the end point thickness is about 1 mm thereby creating a ratio of
about 4.5. The face insert ratio may generally be between 0.5 and
10. However, in some embodiments, the face insert ratio may be less
than 1.0, less than 0.8, or less than 0.7. In other embodiments,
the face insert depth 3746 is greater than 0.2 mm and less than 10
mm or greater than 0.5 mm and less than 2.0 mm.
[0269] An adhesive is disposed between the face insert 3734 and the
face insert rear support member 3710. A bond gap is provided
between the rear support member 3710 and a rear surface of the
composite face 3706 where the adhesive material fills the bond gap.
In certain embodiments, the bond gap is less than about 0.8 mm or
less than about 0.2 mm. In a preferred embodiment, the bond gap is
about 0.15 mm or less. In the exemplary embodiment of FIG. 37, the
cover layer 3704 includes an outer edge that is generally coplanar
with the edge of the composite face 3706. In other words, the cover
layer 3704 does not include a return side wall portion.
[0270] FIG. 38 illustrates a sound power estimate diagram in
accordance with the golf club head shown in FIGS. 34A-E and FIG. 35
as measured using the equipment and methodology disclosed above
where the microphone is place 64 inches above the ball impact with
player A (i.e. 110 mph swing speed). The sound power estimate
diagram shows a maximum peak 3800 in sound power occurs at greater
than 3,500 Hz and less than 7,000 Hz. In one embodiment, the
maximum peak 3800 sound power is occurring at greater than 3,750 Hz
and less than 6,500 Hz. The exemplary golf club head of FIGS. 34A-E
and FIG. 35 has a maximum peak 3800 in sound power at 6,003 Hz
while producing a sound power greater than about 0.06 watts but
less than 0.07 watts, at 0.064 watts. The frequency at maximum
sound power can be divided by the offset angle, discussed above, to
create a frequency-to-offset angle ratio (frequency divided by
offset angle) of between 2,333 Hz/degree to 4,666 Hz/degree for a
1.5 degree offset angle. For a sleeve of about 2 degrees, the
frequency-to-offset angle ratio is between 1,750 Hz/degree and
3,500 Hz/degree. The frequency-to-offset angle ratio can range from
1,000 Hz/degree to 7,000 Hz/degree. FIG. 39 illustrates a sound
power estimate diagram of a club head similar to that shown in
FIGS. 34A-E and FIG. 35. However, the club head tested in FIG. 39
includes a titanium cover layer that is adhesively attached to the
composite face insert. The sound power estimate diagram shows a
maximum peak 3900 in sound power is occurs at greater than 3,000 Hz
and less than 6,000 Hz. In the embodiment shown in FIG. 39, the
maximum peak 3900 sound power is occurs at 5,659 Hz while producing
a sound power greater than about 0.1 watts but less than 0.2 watts,
and greater than 0.125 watts but less than 0.19 watts. The exact
sound power generated by the embodiment of FIG. 39 is 0.188
watts.
[0271] Equation 10 creates a maximum power to frequency ratio
defined below:
Max . Sound Power - to - Freq . Ratio = Maximum Sound Power Freq .
of the Max . Sound Power Eq . 10 ##EQU00003##
[0272] The maximum sound power-to-frequency ratio is greater than
about 2.5*10.sup.-5 watts/hertz and less than about 5*10.sup.-5
watts/hertz, or greater than 1*10.sup.-5 watts/hertz and less than
4.5*10-5 watts/hertz. For example, the embodiment of FIG. 39 has a
maximum sound power-to-frequency ratio of about 3.3*10.sup.-5
watts/hertz and the embodiment of FIG. 38 has a maximum sound
power-to-frequency ratio of about 1.1*10.sup.-5 watts/hertz. In
some embodiments, the maximum sound power-to-frequency ratio is
between 3.0*10.sup.-5 watts/hertz and 4.5*10.sup.-5
watts/hertz.
[0273] In addition, a frequency-to-volume ratio at the maximum
sound power is defined below in Equation 11:
Frequency - to - Volume Ratio = Freq . of Max . Sound Power Volume
Eq . 11 ##EQU00004##
[0274] The frequency-to-volume ratio can be greater than 6.0
hertz/cc and less than about 16 hertz/cc, or greater than 7.0
hertz/cc and less than about 15 hertz/cc, or between 7.0 hertz/cc
and 10 hertz/cc. For example, the frequency-to-volume ratio of the
exemplary embodiment of FIG. 38 is about 13.4 hertz/cc for a
maximum frequency of 6,003 Hz and a volume of 448 cc. In another
exemplary embodiment of FIG. 39, the frequency-to-volume ratio is
about 13.1 for a maximum frequency of 5,659 Hz and a volume of 430
cc.
[0275] A characteristic time test was performed on the embodiments
of FIGS. 38 and 39, as defined and performed by the USGA in the
United States Golf Association Technical Description of the
Pendulum Test, Revised Version, Discussion of points raised during
Notice & Comment period (November 2003), the disclosure of
which is incorporated by reference in its entirety. The procedure
of measuring characteristic time and slope is performed according
to the R&A Rules Limited and USGA, Procedure for Measuring the
Flexibility of a Driving Club, Revision 1.1 (January 2004)
publication.
[0276] The slope formed from the trend-line of the data points used
to calculate the characteristic time is defined as the
"characteristic time slope". In the embodiments described, the
characteristic slope is greater than 5 and less than 90, or greater
than 10 and less than 45, or greater than 10 and less than 50, or
greater than 12.5 and less than 30, or greater than 15 and less
than 30, or between 15 and 20. In some embodiments, the
characteristic slope is between 50 and 60, or between 50 and 90, or
between 50 and 80, or between 50 and 150, or between 10 and 150. By
way of example, the example club head tested in FIG. 38 has a
characteristic time of 231 .mu.s and a characteristic time slope of
62.8. In contrast, the embodiment disclosed in FIG. 39 has a
characteristic time of 226 .mu.s and a characteristic time slope of
37.6. FIG. 40 illustrates an example of a characteristic time slope
of a club head constructed of the design in FIG. 35 and FIG. 38. In
FIG. 40, the characteristic time slope is about 225 .mu.s when
corrected according to the USGA rules for a polymer coating
described above of about 400 .mu.m. The slope as shown in the
equation of FIG. 40 is 65 based on the corrected USGA value. All
slopes and CT values discussed herein are the corrected USGA value
which accounts for special face coatings such as polymers.
[0277] The fibers of the composite material are arranged in a
quasi-isotropic layup of less than 10 mm thickness, as described
above, and can have a layup tensile strength of greater than 100
MPa and less than 9000 MPa, or greater than 200 MPa and less than
1500 MPa, or greater than 300 MPa and less than 1000 MPa. All tests
conducted relative to the term "layup", as used herein, refers to
the quasi-isotropic layup after curing when the resin and the
panels of carbon fiber have created a uniform face insert body. In
one exemplary embodiment shown in FIG. 38, the composite material
layup has a tensile strength of about 689 MPa to about 773 MPa with
an average of about 737 MPa taken over a plurality of measurements.
When examining individual carbon fibers, a high tensile strength
composite fiber is contemplated such as composites having a tensile
strength of 4.0 GPa and less than 6.0 GPa, or greater than 4.5 GPa
and less than about 5.5 GPa. In one exemplary embodiment shown in
FIG. 38, the composite fiber has a tensile strength of 4.83
GPa.
[0278] In addition, the composite material quasi-isotropic layup
described above has a tensile modulus of elasticity of greater than
10 GPa and less than 200 GPa, or greater than 20 GPa and less than
150 GPa, or greater than 20 GPa and less than 100 GPa. In one
exemplary embodiment shown in FIG. 38, the composite material layup
has a tensile modulus of elasticity of about 38 GPa to about 45
GPa, with an average of about 41 GPa taken over a plurality of
measurements. When examining individual carbon fibers, a high
tensile modulus of elasticity composite fiber is contemplated such
as composites having a tensile modulus of elasticity of greater
than 200 GPa and less than about 300 GPa, or greater than 225 GPa
and less than about 275 GPa. In one embodiment of FIG. 38, the
tensile modulus of elasticity of the composite fiber is 234
GPa.
[0279] A strength-to-modulus layup ratio is defined as the tensile
strength of the composite quasi-isotropic layup divided by the
tensile modulus of the elasticity of the composite quasi-isotropic
layup, as shown in Equation 12:
Strength - to - Modulus Layup Ratio = Layup Tensile Strength Layup
Tensile Modulus of Elasticity .times. 100 Eq . 12 ##EQU00005##
[0280] The strength-to-modulus layup ratio is greater than 0.5 and
less than 10.0, or greater than 1.0 and less than 10.0, or greater
than 2.0 and less than 8.0, or greater than 1.0 and less than 2.0.
In one exemplary embodiment of FIG. 38, the strength-to-modulus
layup ratio is about 1.8 (calculated by 737 MPa/41 GPa).
[0281] Furthermore a strength-to-modulus fiber ratio is defined as
the tensile strength of the fiber alone divided by the tensile
modulus of the elasticity of the fiber alone, as shown in Equation
13:
Strength - to - Modulus Fiber Ratio = Fiber Tensile Strength Fiber
Tensile Modulus of Elasticity .times. 100 Eq . 13 ##EQU00006##
[0282] The strength-to-modulus fiber ratio is greater than 1.0 and
less than 10.0, or greater than 2.0 and less than 8.0, or greater
than 2.0 and less than 3.0. In one exemplary embodiment of FIG. 38,
the strength-to-modulus fiber ratio is about 2.1 (calculated by
4.83 GPa/234 GPa). When comparing the strength-to-modulus layup
ratio and the strength-to-modulus fiber ratio, the embodiment of
FIG. 38 shows the strength-to-modulus layup ratio being less than
the strength-to-modulus fiber ratio.
[0283] The exemplary embodiment of FIG. 38 possesses a unique
characteristic in that the strength-to-modulus layup ratio of 1.8
is less than the strength-to-modulus fiber ratio of 2.1 satisfying
the inequality of Equation 14:
0.5 < strength - to - modulus layup ratio strength - to -
modulus fiber ratio < 1 Eq . 14 ##EQU00007##
[0284] A layup-to-fiber ratio is shown in Equation 14 and is
defined as the strength-to-modulus layup ratio divided by the
strength-to-modulus fiber ratio. Maintaining a layup-to-fiber ratio
within the above described range ensures a durable face insert is
produced and can also have a positive impact on the sound
characteristics of the overall golf club head. In the exemplary
embodiment of FIG. 38, a layup-to-fiber ratio of about 0.86 is
produced (calculated by 1.8/2.1). In some embodiments, the
layup-to-fiber ratio may be greater than 0.1 and less than 1, or
greater than 0.25 and less than 1.
[0285] In certain embodiments, the club head height is between
about 63.5 mm to 71 mm (2.5'' to 2.8'') and the width is between
about 116.84 mm to about 127 mm (4.6'' to 5.0''). Furthermore, the
depth dimension is between about 111.76 mm to about 127 mm (4.4''
to 5.0''). The club head height, width, and depth are measured
according to the USGA rules.
[0286] In view of the many possible embodiments to which the
principles of the disclosed invention may be applied, it should be
recognized that the illustrated embodiments are only preferred
examples of the invention and should not be taken as limiting the
scope of the invention. It will be evident that various
modifications may be made thereto without departing from the
broader spirit and scope of the invention as set forth. The
specification and drawings are, accordingly, to be regarded in an
illustrative sense rather than a restrictive sense.
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