U.S. patent application number 10/198233 was filed with the patent office on 2002-12-05 for golf club head with face wall flexure control system.
Invention is credited to Allen, Dillis V., Raymont, William R..
Application Number | 20020183134 10/198233 |
Document ID | / |
Family ID | 46279307 |
Filed Date | 2002-12-05 |
United States Patent
Application |
20020183134 |
Kind Code |
A1 |
Allen, Dillis V. ; et
al. |
December 5, 2002 |
Golf club head with face wall flexure control system
Abstract
A metal club head designed for increased flexure at ball impact
including a face wall reinforcing network that increases in
thickness from the perimeter wall to a point near the face wall
geometric center.
Inventors: |
Allen, Dillis V.; (Elgin,
IL) ; Raymont, William R.; (Las Vegas, NV) |
Correspondence
Address: |
DILLIS V. ALLEN
ATTORNEY AT LAW
1080 Nerge Road, Suite 205
Elk Grove Village
IL
60007
US
|
Family ID: |
46279307 |
Appl. No.: |
10/198233 |
Filed: |
July 18, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10198233 |
Jul 18, 2002 |
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09344172 |
Jun 24, 1999 |
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6354961 |
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Current U.S.
Class: |
473/329 ;
473/342; 473/345; 473/349 |
Current CPC
Class: |
A63B 53/047 20130101;
A63B 60/52 20151001; A63B 53/0408 20200801; A63B 53/045 20200801;
A63B 53/0437 20200801; A63B 53/0466 20130101; A63B 53/04 20130101;
A63B 53/0433 20200801; A63B 60/00 20151001; A63B 53/0416 20200801;
A63B 53/0454 20200801; A63B 53/0458 20200801 |
Class at
Publication: |
473/329 ;
473/345; 473/349; 473/342 |
International
Class: |
A63B 053/04 |
Claims
1. A golf club head, comprising: a face wall, a perimeter wall
surrounding at least a major portion of the face wall and attached
to a perimeter of the face wall, said club head having a shaft
receiving hosel therein, said face wall having a geometric center
and extending outwardly from that center 360 degrees toward the
perimeter wall, said face wall increasing in effective thickness
from a point A (t.sub.a) near the perimeter wall toward the
geometric center to an effective thickness (t.sub.b) at a point B
near the geometric center where t.sub.b/t.sub.a is at least
3.0.
2. A golf club head as defined in claim 1, wherein t.sub.b/t.sub.a
is in the range of about 3.0 to 7.0.
3. A golf club head, comprising: a face wall, a perimeter wall
surrounding at least a major portion of the face wall and attached
to a perimeter of the face wall, said club head having a shaft
receiving hosel therein, said face wall having a geometric center
and extends outwardly from that center 360 degrees toward the
perimeter wall, said face wall increasing in effective thickness
from a point A (t.sub.a) near the perimeter wall in a horizontal
direction toward the geometric center to an effective thickness
t.sub.b at a point B near the geometric center, where the effective
thickness (t) of the face wall increases at a constant rate or
higher from point A to point B.
4. A golf club head, comprising: a face wall, a perimeter wall
surrounding at least a major portion of the face wall and attached
to a perimeter of the face wall, said club head having a shaft
receiving hosel therein, said face wall having a geometric center
and extending outwardly from that center 360 degrees toward the
perimeter wall, said face wall having a substantially uniform
thickness, and means for increasing the effective thickness of the
face wall from near the perimeter wall to a point near the
geometric center including a rib network formed integrally with the
face wall, said rib network increasing thickness from near the
perimeter wall to a point near the geometric center.
5. A golf club head as defined in claim 4, wherein the rib network
includes a generally annular or elliptical rib formed integrally
with the face wall near the geometric center of the face wall and
extending rearwardly therefrom a substantial distance.
6. A golf club head as defined in claims 4 or 5, wherein the rib
network includes a plurality of ribs extending from about the
geometric center generally radially toward the perimeter wall.
7. A golf club head as defined in claim 6, wherein the plurality of
ribs increase in height from near the perimeter wall to a point
near the geometric center at a constant rate or higher.
8. A wood club head, comprising: a face wall having a loft and
being curved in a horizontal plane defining bulge and curved in a
vertical plane defining roll, a perimeter wall surrounding and
enclosing the face wall, said face wall having a substantially
uniform thickness, and means for increasing the effective thickness
of the face wall from near the perimeter wall to a point near the
geometric center including a rib network formed integrally with the
face wall with at least a plurality of the ribs extending from the
point near the geometric center to the perimeter wall, said
plurality of ribs having an increasing thickness from near the
perimeter wall to the point near the geometric center.
9. A wood club head as defined in claim 8, wherein the rib network
includes a generally annular or elliptical rib formed integrally
with the face wall and extending rearwardly therefrom a substantial
distance, said annular or elliptical rib having a center
approximately near the geometric center of the club face, the
plurality of ribs extending integrally from the annular or
elliptical rib generally radially toward the perimeter wall.
10. A wood club head as defined in claim 8, wherein the plurality
of ribs increase in height from near the perimeter wall to the
point near the geometric center at a constant rate or higher.
11. A wood club head as defined in claim 10, wherein the ribs
increase in height from near the perimeter wall to the point near
the geometric center and are exponentially curved.
Description
RELATED APPLICATION
[0001] This application is a Continuation in Part of U.S.
application Ser. No. 09/344,172, Filed: Jun. 24, 1999, entitled
"GOLF CLUB FACE FLEXURE CONTROL SYSTEM" filed in the name of Dillis
V. Allen, and is related to U.S. application Ser. No. ______,
Filed: ______, entitled "IMPROVED GOLF CLUB HEAD WITH FACE WALL
FLEXURE CONTROL SYSTEM".
BACKGROUND OF THE INVENTION
[0002] In the last several years, the USGA has struggled with
attempting to devise a fair test to limit the trampoline effect of
the face wall at ball impact. Recent innovation in titanium alloys,
and particularly the Beta titanium alloys has enabled the golf club
head designer to dramatically reduce face thickness and achieve
greater face flexure without face failure. Faced with the politics
of golf integrity, which pits the golf traditionalists against
those seeking enhanced performance from new technology, the USGA
has devised a rebound test where a ball is fired at a test sample
club and inlet and outlet velocities are measured. If ball exit
velocities exceed the inlet velocity by a predetermined fractional
multiplica (<.90) not relevant to this discussion, the club
fails the test. There is also a great debate as to whether such
USGA testing is in the best interest of golf, particularly for
amateur players, who Arnold Palmer characterizes as a group that
should not be bound by these strict USGA rules, but should be
permitted use of clubs that do not conform to the present (July
2001) USGA testing rules.
[0003] In any event, the USGA rules and the concomitant colossal
debate over which clubs are legal and which are not has created a
large market for both clubs that marginally pass the USGA rules and
those that are illegal under the USGA rules. The latter market is
enhanced because the USGA rules are not applicable outside North
America.
[0004] In this environment, the present invention is directed
toward a plurality of techniques for increasing the flexure of the
face wall of a golf club without exceeding the elastic limit
anywhere across the face wall. Conventional techniques for varying
face wall flexure are: (1) face wall material selection; (2) face
wall shape variation; (3) face wall area control; (4) face wall
heat treatment, and, of course; (5) face wall thickness
changes.
[0005] By using trial and error techniques, many golf club head
designers have combined these factors to achieve what is now termed
a "non-conforming" club head. Several manufacturers including
Callaway Golf and Ping Golf, as well as many of their imitators,
have a variable thickness face wall where the face is thicker near
the point of ball impact and thins as it approaches the perimeter
wall. The problem with this technique is the thickness of the face
must be over 0.125 inches over a major portion of the face wall to
prevent face wall failure, and face thickness variation is limited
to 2.times. because of club head weight limitations. The present
invention solves these problems.
[0006] Investment casting techniques innovated in the late 1960s
have revolutionized the design, construction and performance of
golf club heads up to the present time. Initially only novelty
putters and irons were investment cast, and it was only until the
early years of the 1980s that investment cast metal woods achieved
any degree of commercial success. The initial iron club heads that
were investment cast in the very late 1960s and early 1970s
innovated the cavity backed club heads made possible by investment
casting which enabled the molder and tool designer to form rather
severe surface changes in the tooling that were not possible in
prior manufacturing techniques for irons which were predominantly
at that time forgings. The forging technology was expensive because
of the repetition of forging impacts and the necessity for
progressive tooling that rendered the forging process considerably
more expensive than the investment casting process and that
distinction is true today although there have been recent
techniques in forging technology to increase the severity of
surface contours albeit them at considerable expense.
[0007] The investment casting process, sometimes known as the lost
wax process, permits the casting of complex shapes found beneficial
in golf club technology, because the ceramic material of the mold
is formed by dipping a wax master impression repeatedly into a
ceramic slurry with drying periods in-between and with a silica
coating that permits undercutting and abrupt surface changes almost
without limitation since the wax is melted from the interior of the
ceramic mold after complete hardening.
[0008] This process was adopted in the 1980s to manufacture
"wooden" club heads and was found particularly successful because
the construction of these heads requires interior undercuts and
thin walls because of their stainless steel construction. The metal
wood club head, in order to conform to commonly acceptable club
head weights on the order of 195 to 210 gms. when constructed of
stainless steel, must have extremely thin wall thicknesses on the
order of 0.020 to 0.070 inches on the perimeter walls to a maximum
of 0.125 inches on the forward wall which is the ball striking
surface. This ball striking surface, even utilizing a high strength
stainless steel such as 17-4, without reinforcement, must have a
thickness of at least 0.125 inches to maintain its structural
integrity for the high club head speed player of today who not
uncommonly has speeds in the range of 100 to 150 feet per second at
ball impact.
[0009] Faced with this dilemma of manufacturing a club head of
adequate strength while limiting the weight of the club head in a
driving metal wood in the range of 195 to 210 gms., designers have
found it difficult to increase the perimeter weighting effect of
the club head.
[0010] Metal woods by definition are perimeter weighted because in
order to achieve the weight limitation of the club head described
above with stainless steel materials, it is necessary to construct
the walls of the club head very thin which necessarily produces a
shell-type construction where the rearwardly extending wall extends
from the perimeter of the forward ball striking wall, and this
results in an inherently perimeter weighted club, not by design but
by a logical requirement.
[0011] Prior attempts to manufacture very large stainless steel
metal club heads with larger than normal faces has proved
exceedingly difficult because of the 195 to 210 gm. weight
requirements for driving club heads to achieve the most desirable
club swing weights. Thus, to the present date stainless steel
"jumbo" club heads have been manufactured with standard sized face
walls, deeply descending top walls from the front to the rear of
the club head, and angular faceted sole plates all designed to
decrease the gross enclosed volume of the head but which do not
detract from the apparent, not actual, volumetric size of the head.
This has led to many manufacturers switching from stainless steel
to aluminum and titanium alloys, which are of course lighter, to
enlarge the head as well as the face.
[0012] A further problem in the prior art references which suggest
utilizing these rigidifying elements, is that they are completely
silent on how these reinforcing elements, when not cast into the
face wall, are attached into the club head. And the method of
attachment, as will be seen from the present invention, is critical
to the benefits of increasing resonant frequency and rebound of the
face wall in accordance with the present invention. Presently known
bonding techniques are not sufficient to yield these benefits.
[0013] Still another of these prior references suggests making the
head of synthetic material and the support rod of a similar
material, but these low modulus and soft materials cannot
significantly raise the resonant frequency or rebound time of the
ball striking face wall.
[0014] The following patents or specifications disclose club heads
containing face reinforcing elements:
[0015] Foreign Patents:
[0016] British Patent Specification, No. 398,643, to Squire, issued
Sep. 21, 1933;
[0017] United States Patents:
[0018] Clark, U.S. Pat. No. 769,939, issued Sep. 13, 1904
[0019] Palmer, U.S. Pat. No. 1,167,106, issued Jan. 4, 1916
[0020] Barnes, U.S. Pat. No. 1,546,612, issued Jul. 21, 1925
[0021] Drevitson, U.S. Pat. No. 1,678,637, issued Jul. 31, 1928
[0022] Weiskoff, U.S. Pat. No. 1,907,134, issued May 2, 1933
[0023] Schaffer, U.S. Pat. No. 2,460,435, issued Feb. 1, 1949
[0024] Chancellor, U.S. Pat. No. 3,589,731, issued Jun. 29,
1971
[0025] Glover, U.S. Pat. No. 3,692,306, issued Sep. 19, 1972
[0026] Zebelean, U.S. Pat. No. 4,214,754, issued Jul. 29, 1980
[0027] Schmidt, U.S. Pat. No. 4,511,145, issued Apr. 16, 1985
[0028] Yamada, U.S. Pat. No. 4,535,990, issued Aug. 20, 1985
[0029] Chen, et al., U.S. Pat. No. 4,681,321, issued Jul. 21,
1987
[0030] Kobayashi, U.S. Pat. No. 4,732,389, issued Mar. 22, 1988
[0031] Shearer, U.S. Pat. No. 4,944,515, issued Jul. 31, 1990
[0032] Shiotani, et al., U.S. Pat. No. 4,988,104, issued Jan. 29,
1991
[0033] Duclos, U.S. Pat. No. 5,176,383, issued Jan. 5, 1993
[0034] Atkins, U.S. Pat. No. 5,464,211, issued Nov. 7, 1995
[0035] Rigal, et al., U.S. Pat. No. 5,547,427, issued Aug. 20,
1996
[0036] Lu, U.S. Pat. No. Re. 35,955, reissued Nov. 10, 1998
[0037] Noble, et al., U.S. Pat. No. 5,954,596, issued Sep. 21,
1999
SUMMARY OF THE PRESENT INVENTION
[0038] In accordance with the present invention, a metal club head
is designed for increased flexure at ball impact including a pleat
or alternatively a tongue and groove connection in the perimeter
wall that provide reduced resistance to face wall expansion at ball
impact, and more energy transfer to the ball, and a face wall
reinforcing network that increases in height from the perimeter
wall to a point near the face wall geometric center.
[0039] The golf club head at ball impact has been extremely
difficult to analyze from a design standpoint because of the
peculiar traditional shape, particularly of the metal wood, the
singular point of attachment of the shaft at the hosel which has no
analogy to a vise holding the head during testing, the bulge and
roll of the club face, and the peculiar effect of the perimeter
wall on the face dynamics. The present invention does not solve
these design problems, but focuses on a system for increasing face
flexure and energy transfer to the ball.
[0040] This invention or inventions, bifurcates the present
solution into two parts; the first is a face reinforcing network
that increases in thickness from the perimeter wall to a point near
the geometric center of the club face according to sound
mathematical approximations. The face wall thinning techniques in
the prior art, while helpful, do not have face wall thickness
variations that optimize face wall flexure. In the present design
face wall thickness, or more accurately effective thickness,
increases from the perimeter wall to near the face wall geometric
center by a factor in the range of 3.0 to 7.0 times and does so
geometrically in its more specific definition.
[0041] Effective thickness, as used herein, is the flexure
characteristic of the present rib reinforcement face compared to a
solid face wall of varying thickness without any reinforcing ribs.
Thus, using the present technique, the present rib design can
achieve the same face flexure pattern as a solid faced club having
a face wall thickness variation of up to seven fold, without adding
the excessive weight of that solid face wall.
[0042] In its broadest aspects, some of these principles can be
utilized in solid faced clubs with variable face thickness, such as
shown in the Kubica, et al., U.S. Pat. Nos. 5,906,549 and
5,954,596. However, the narrow rib reinforcing network of the
present invention permits a far greater increase in effective face
thickness than solid faced club heads, because it provides greater
reinforcement without the trade-off of increased face weight. That
is, if in a solid face wall club with face thickness thinning near
the perimeter wall, the thickness at the face center were seven
times the thickness at the perimeter wall, the thickness at the
center would be about 0.434 inches and the club head would be far
overweight. The present invention solves this problem.
[0043] Thus, according to the present invention, the face wall can
be very thin and light, as thin as 0.062 inches when made of a high
quality beta titanium such as 15 Mo 3-3 hardened. Yet, the ribbing
network gives the same effect as face increase variation of 3 to 7
times in a solid faced head.
[0044] These principles are based upon the mathematical premise
that face wall stress at ball impact is concentrated in a very
small area surrounding and behind the ball. This is due in part to
the outward and inward moments on the face caused by the perimeter
wall and the thickness and size of the face wall itself.
[0045] The cross sectional area of the face wall at incrementally
increasing radii, r.sub.1, r.sub.2, etc. from the center to the
perimeter increases more significantly than previously thought.
These areas define the face wall's ability to resist stress at
these radii and thus the largest sectional area, at the perimeter
wall, is capable of handling the greatest load. And this is what
leads to the conclusion the face wall needs to be dramatically
thinner at the perimeter wall than at the face wall center to
achieve not only maximum deflection at the face wall center, but
uniform deflection from the geometric center out to the perimeter
wall. This also maximizes the spring effect of the face wall and
energy transfer to the ball.
[0046] Simple beam theory, discussed below, while helpful, does not
properly analyze club face wall stress because of (1) the torque
applied to the face wall by the perimeter wall and (2) the
increasing cross-sectional area of the face wall as the radius
about the geometric center increases. And while simple calculations
indicate the cross sectional area (the area cut by a hole saw
around the geometric center) increases linearly; i.e. Kr, as the
radius r around the center increases, this ignores the moments or
torque applied to the perimeter of the face wall by the perimeter
wall at ball impact.
[0047] The net effect of these moments caused by the perimeter wall
on the face wall is to strengthen the face wall particularly near
the perimeter wall. To compensate for this effect, the present rib
network increases from zero or near zero near or at the perimeter
wall, geometrically at K(X+BX.sup.3).sup.1, to a thickness in one
embodiment of about 0.125 near the geometric center. (Note the rib
height in the drawings are exaggerated). 1. K and B are
constants
[0048] The second design feature of the present invention, claimed
in the above "Related Application", is a pleat or alternatively
tongue and groove connections between the perimeter wall and the
face wall that each permit the face wall to more easily expand
radially (flatten) in the plane of the face wall. These features
are independent of and can be used without the above face wall
ribbing. Metal woods normally have face walls curved in orthogonal
planes, the curve in a horizontal plane being formed on a radius
called "bulge", and the curve in a vertical plane being found is a
radius referred to as "roll". Face curvature by itself reduces face
wall flexure more than flat faces. Also, the moments created by the
perimeter wall, which exist in both flat and curved face walls,
resist uniform face deflection and contribute to localized face
wall distortion around the ball at impact. If the face wall is
permitted to more easily flatten at impact, stresses in the face
wall are spread more uniformly across the face wall and the face
wall deflects more uniformly from the geometric center to the
perimeter wall upon impact.
[0049] It should be understood at this point that effective face
thickness variation and pleat or tongue and groove connectors at
the perimeter wall are all designed to achieve similar ends; i.e.,
maximize face wall deflection. Thus, they can be utilized in club
head design independent of one another, or together, as shown in
the drawings embodiments where they have a cumulative effect toward
those ends.
[0050] The perimeter wall pleat or the tongue and groove
connections are in fact separate embodiments. In the pleat
embodiment, the face wall and a short portion of the perimeter wall
are cast in one piece and hardened. The perimeter wall portion has
a concave perimeter pleat that acts as a pair of opposed Bellville
springs. As these springs compress on impact, the outer diameter of
the springs increases and thus lessens the resistance the perimeter
wall has to face wall expansion. And the Bellville springs, upon
recovery after compression, deliver energy back to the ball as it
leaves the club face wall.
[0051] In the other embodiment, the tongue and groove connection,
the face wall floats slightly in the perimeter wall in all
directions, permitting face wall expansion and reducing resistance
to face wall deflection.
[0052] Other objects and advantages will appear more clearly from
the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a front view of the club head according to the
present invention;
[0054] FIG. 2 is a top view of the club head according to the
present invention;
[0055] FIG. 3 is a right side view of the club head according to
the present invention;
[0056] FIG. 4 is a left side view of the club head according to the
present invention;
[0057] FIG. 5 is a horizontal mid-section of the front piece of the
club head;
[0058] FIG. 6 is a vertical mid-section of the front piece of the
club head;
[0059] FIG. 7 is a rear view of the front of the front piece of the
club head illustrated in FIGS. 5 and 6;
[0060] FIG. 8 is a left side view of the rear piece of the club
head according to the present invention;
[0061] FIGS. 9, 10, 11 and 12 are beam theory drawings;
[0062] FIGS. 13 and 14 are beam theory drawings illustrating shear
and moments;
[0063] FIGS. 15 and 16 are disk theory analysis drawings;
[0064] FIGS. 17 and 18 are fragmentary sections illustrating a
tongue and groove embodiment of the present invention, and;
[0065] FIG. 19 is a fragmentary section of a still further tongue
and groove connection embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0066] It should be understood that the drawings (except FIGS. 18
and 19) of the present club head are to scale 1"=1", within of
course the limits of the patent draftsman, and therefore,
dimensions that are not specifically set forth either as single
dimensions, or ranges, may be measured on the drawings and as such
are within the disclosure of the present invention and these
dimensions may after the filing of the present invention, be added
to the disclosure, specification or claims with the modifier
"substantially" without constituting new matter.
[0067] As noted above, both simple single beam technology and
circular disc technology do not have exact analogy to the dynamics
of metal golf clubs and particularly metal woods, but do provide a
useful comparison for experimentation. The bulge and roll of the
club face is simulated in FIGS. 9 to 12. In FIGS. 9 and 10, the
convex face wall 10 easily flattens upon impact force P to the flat
or concave positions shown in FIG. 10. This occurs when reaction
forces F.sub.1 and F.sub.2 act only in a vertical direction. What
actually happens is depicted in FIGS. 11 and 12. The perimeter wall
creates moments on the face depicted as M.sub.1 and M.sub.2 that
resist wall flattening.
[0068] So long as the face wall is convex as shown in both FIGS. 11
and 12, the perimeter wall will also exert inward forces F.sub.3
and F.sub.4 on the face wall, resisting flattening to the FIG. 10
position. The result of these forces creates the localized
depression of the face wall around the golf ball illustrated in
FIG. 12 that is responsible for face wall failure if the designer
simply attempts to uniformly thin the face wall. This localized
depression represents the condition the present invention
eliminates.
[0069] The perimeter wall, of course, has a positive dynamic effect
on the face wall and energy transfer to the ball. Thus, the
appropriate design approach is to balance the effects of a FIGS. 9
and 10 design with the too restrictive effect of the FIGS. 11 and
12 design and to that end the present inventions are directed.
[0070] A review of beam and disc technology confirms these
principles. FIG. 13 shows a single simple beam, centrally loaded
that in part analogizes FIGS. 9 and 10. The shear forces across the
beam are constant and the moments at the ends of the beam are zero.
The maximum deflection at the center of beam under a concentrated
load at midspan are: 1 MAX = PL 3 48 E I where P = force , L =
Length E = Modulus of Elasticity Eq . ( 1 )
[0071] Compare this relationship to FIG. 14, which illustrates the
same force P applied to a single beam centrally when the beam is
fixed at both ends. Note in FIG. 14 the reverse moments M applied
to beam. This simulates the effect of the perimeter wall on the
face wall, although not precisely. The maximum deflection of the
beam in this system under the same load P is defined as: 2 MAX = PL
3 192 E I Eq . ( 2 )
[0072] Somewhat over-simplified, cancelling out the common factors
in equations (1) and (2), the non-restrictive system in FIG. 13 has
four times the maximum deflection under the same load as the system
in FIG. 14.
[0073] FIGS. 15 and 16 illustrate circular disc systems that
somewhat complicate the analysis of simple single beam review. In a
single beam the cross section of the beam stays constant, while in
the disc system, the cross sections of the disc, defined at circles
around any radius, increase as one moves outwardly from the center
or point of theoretical ball impact. This is why the disc analogy
is closer to a club head than the beam.
[0074] In FIG. 16 (analogous to FIGS. 9, 10 and 13), the maximum
deflection is: 3 MAX = 693 Pr 2 400 Et 3 where E = Modulus of
Elasticity P = Force r = plate radius t = plate thickness Eq . ( 3
)
[0075] In FIG. 17 analogous to FIGS. 11, 12, and 14, the maximum
deflection is: 4 MAX = 273 W Pr 2 400 Et 3
[0076] Same constants as above.
[0077] Thus, the disc unrestrained in all directions at its
perimeter has a maximum deflection 2.54 times the maximum
deflection of the disc fixed from movement in all directions at its
perimeter. This in part explains the significant resistive effect
of the perimeter wall.
[0078] Referring to the drawings and particularly FIGS. 1 to 8 and
17, 18, and 19, a "jumbo" club head 10 is illustrated, preferably
entirely constructed of a high performance forged or cast beta
titanium material such as 15Mo3-3. In the embodiment disclosed in
FIGS. 1 to 8, the head is constructed of a forward piece 11
including a face wall 12, and a short perimeter wall 13, welded to
a rear piece 15 illustrated in FIG. 8 including a sole plate
portion 17, a side and rear wall portion 18, and a crown portion
19. Note that the forward portion 11 carries an integral hosel 20
having a standard shaft receiving bore 21 therein that also extends
through hosel upper portion 22.
[0079] As noted above, the drawings, as filed, are substantially to
scale and the dimensions in some aspects of the present invention
are important to the performance of the golf club head.
[0080] Firstly, with respect to the size and shape of the face wall
12, and particularly as depicted in FIG. 1, the face wall has a
horizontal length F of 4.344 inches, and a vertical height E of
2.344 inches.
[0081] It should be understood that the geometry of the face 12 is
designed to provide more uniform deflection across the face upon
ball impact, and while the vertical height E in the specific
embodiment is 2.344 inches, the advantages of the face geometry can
be achieved in face walls having a height greater than 1.9 inches.
One important aspect of achieving more uniform face wall
deflection, according to the present invention, is to provide a
more circular face which enhances uniform face wall deflection.
[0082] Toward that end the central upper edge 25 and the lower
central edge 26 each have a radius of 3.25 inches although the
benefits of the present invention can be achieved with these radii
in the range of 2.75 to 3.50 inches. The upper edges 28 and 29
adjacent central edge portion 25 and the lower edge portions 31 and
32 adjacent the lower edge central portion 26 are tangent to the
central portions 25 and 26 and are substantially straight to
increase the face height at toe portion 33 and heel portion 34 of
the face wall.
[0083] The overall volume of the club head 10 is in the range of
370 cc., noting that is conventional to quantify club head volume
in metric units even though the dimensions set forth in this
specification are in inches. Toward this specific volume, and
referring to FIG. 1, the overall horizontal length of the club head
10 viewed from the front from the furthest extent of the toe wall
35 from the heel wall 36 identified by the letter G is 4.94 inches,
and the overall height of the club from the sole portion 17 to the
uppermost portion of the crown wall 15 identified by the letter D
in FIG. 1 is 2.62 inches. Overall club head length L is 4.156. The
hosel 22 has a substantial inset as seen by the ratio of A/B.
[0084] As seen in FIGS. 5, 6, and 7, the face wall 12 has a ribbed
reinforcing network 38 that promotes the uniform deflection of the
face wall from the geometric center to the perimeter wall portion
13. That is, the network 38 is designed so there will be a straight
line deflection of the face wall 12 from the geometric center G.C.
to the perimeter wall 13 in a fashion similar to the straight line
deflection of the strings in a tennis racket upon ball impact. Note
in the plane of FIG. 5, which is a horizontal plane extending
through the geometric axis of the face wall, that the face 12 is
curved indicating it has "bulge", and in the plane of FIG. 6, which
is a vertical plane taken through the geometric center of the face
wall, the face wall 12 is also curved indicating the face wall has
"roll". The curvature of the face wall in these two orthogonal
planes may, for example, be on the order of 15 inches. Note also in
FIG. 6 that the face wall has a "loft" of 10 degrees, and typically
loft will vary in the driver club from 6 degrees to about 11
degrees.
[0085] It should be understood at this point that certain aspects
of the present invention can be applied to fairway woods and
iron-type clubs as well. Irons, however, have no roll or bulge
curvatures and hence have less resistance to face wall deflection
assuming equal face thicknesses and size.
[0086] The network 38 is designed to provide a far greater
stiffness variation from the geometric center to the perimeter wall
13 than can be achieved with variable solid (ribless) face
thickness. In variable face thickness designs, which are ribless,
face thickness variation can only vary by approximately 2.0. That
is, the thickness of the face wall near the perimeter wall can only
be about half the thickness of the face wall at the geometric
center G.C. without resulting in excessive face wall weight and
excessive overall club head weight. In the present invention,
effective face wall thickness with the rib network 38 can compare
to face thickness variations of 3.0 to 7.0 in ribless designs
without adding excessive weight to the head. It should be
understood, however, that in the range of 7.0, the network 38 will
begin to have excessive face stiffness, which is contrary to the
purpose of the present invention so that the preferable operating
range for the network 38 is closer to 3.0 to achieve maximum face
deflection.
[0087] The face wall 12, according to the present invention, has a
uniform thickness between 0.045 inches and 0.070 inches.
[0088] The network 38 is seen to include an annular rib 42 integral
with and extending rearwardly from the face wall 12. The annular
rib 42 has a depth of between 0.100 to 0.200 inches and a thickness
of 0.062 inches, and the rib 42 has a diameter of approximately
0.750 inches. Extending radially outwardly and integral with both
the annular rib 42 and the face wall 12 are eight ribs 43, 44, 45,
46, 47, 48, 49 and 50, spaced apart approximately 45 degrees in the
plane of FIG. 7, which is a rear view of the club head body forward
piece 11.
[0089] The ribs 45 and 49 (FIG. 6) meet the side of the rib 42
about 0.030 inches below the top of the rib 42 and ribs 44, 46, 50
and 48 join the side of the rib 42 about 0.020 inches below the top
of rib 42.
[0090] Note particularly that near the perimeter wall the ribs 43
to 50 have a height of 0 to promote flexure of the face wall, and
they have their maximum thickness where the ribs join the annular
rib 42. The effective thickness variation has been determined by
comparing the present face and network 38 to a plurality of ribless
faces having face thickness variations from 3.0 to 7.0. This
effective thickness variation, defined as the thickness t.sub.a at
point A near the perimeter wall, and a thickness at a point B near
the geometric center, where t.sub.b/t.sub.a is at least 3.0 and in
the range of 3.0 to 4.0.
[0091] The annular rib 42 may also be elliptical with the major
axis of the ellipse extending horizontally across the face. The
ribs 43 and 50 would then be more equal in length and provide more
uniform deflection of the face in both horizontal and vertical
directions.
[0092] As noted above, in uniform thickness face walls the cross
sectional area of the face about any radius around the geometric
center G.C. increases as the radius about the geometric center
increases. It is this cross sectional area that is proportional to
the ability of the face at any given point on the face to resist
ball impact stresses on the face so that at the geometric center
G.C., where the radius is 0 and the section O, the face wall
(absent the network 38) is at its weakest point in resisting ball
impact forces, and at the perimeter wall at 40 the section is the
greatest and has its greatest resistance to ball impact and thus
the network 38 seeks to weaken the face wall at 40 and to
strengthen the face wall strength at the geometric center G.C.,
utilizing the network 38. These cross sectional areas, which are
effectively the areas scribed by hole saws centered about the
geometric center G.C., increase linearly from the geometric center
to near the perimeter wall. However, this analysis neglects the
effect of the perimeter wall on the face wall, which is, to provide
moments on the face wall tending to maintain the curvature of the
face wall 12. To compensate for the effect of the perimeter wall on
the face wall, the ribs 43 to 50, rather than being straight in
configuration to match the linear variation in face wall cross
sections moving outwardly from the geometric center G.C., are
instead curved to further weaken the face wall moving radially
outwardly from the geometric center to compensate for the moments
acting on the face wall by the perimeter walls around the face
wall.
[0093] Face wall deflection, according to the present invention, is
further enhanced by a pleat 54 illustrated in FIGS. 1 to 7, and an
elastomeric tongue and groove section illustrated in FIGS. 17, 18
and 19. As noted above, the ability of the face wall to flatten
upon ball impact is impeded by the perimeter wall, which in
accordance with the analysis in FIGS. 11, 12, 14, and 16, provides
inward forces on the face wall 12 that inhibit the flattening of
the face wall upon ball impact. The pleat 54 and the tongue and
groove connection 55 reduce the inward forces acting on the face
wall by the perimeter walls.
[0094] The pleat 54, as seen in FIGS. 2 to 8, is formed in the
forward part 13 illustrated in FIG. 7, and extends completely
around the face wall except at the hosel 22. The perimeter wall at
the hosel 22, as seen in FIG. 2, has a slot 56 that connects pleat
portion 54a and pleat portion 54b.
[0095] As seen in FIGS. 5 and 6, the pleat 54 is defined by
perimeter wall portion 59 and perimeter wall portion 60 that are
generally V-shaped in configuration. Wall portion 59 has an angle
of approximately 55 to 60 degrees with respect to a vertical plane
noted in FIG. 5, while wall portion 60 has an angle of about 5 to
10 degrees with respect to that same parallel plane. It should be
understood, however, that the angles of wall portions 59 and 60
vary to accommodate the unique geometry of the crown wall, side
walls, and sole plate of the particular club head under
consideration.
[0096] The walls 59 and 60 are in effect Bellville springs that
collapse slightly upon ball impact and permit face wall perimeter
edge in the plane 61 to move outwardly upon ball impact as the
pleat 54 collapses slightly in accordance with well known Bellville
spring geometry. It should also be noted that the pleat 54 as it
expands as the ball leaves the face 12, releases its stored energy
to the ball enhancing ball exit velocity.
[0097] The slot 56 weakens the face slightly at the hosel 22 to
prevent the hosel from rigidifying the face excessively at this
point. The pleat may be covered by rings coplanar with the outer
walls of the club head for aesthetics.
[0098] As seen in FIGS. 17 and 18, the elastomeric tongue and
groove connection 55 includes a rectangular perimeter recess 66 in
the perimeter of the face wall 12a, and a perimeter tongue 67
integrally formed on an annular bezel 68 welded to an annular
recess 69 in the forward edge of perimeter wall 70. A U-shaped
elastomeric ring 72 is mounted in recess 66 and around the tongue
67. Ring 72 has a durometer in the range of 50 to 90 Shore A. This
elastomeric connection permits the face wall to flatten more easily
upon impact as the face wall 12a twists about the tongue 67 in the
plane of FIG. 18. In addition to facilitating the twisting of the
face wall 12a as it flattens, the elastomeric connection 55 also
permits radial expansion of the face wall 12a, which of course
tends to occur as the face wall flattens from its roll and bulge
unloaded configuration.
[0099] An alternative elastomeric connection 76 is illustrated in
FIG. 19 where tongue 77 is formed on the face wall and groove 78 is
formed on bezel 79.
* * * * *