U.S. patent number RE39,178 [Application Number 09/567,180] was granted by the patent office on 2006-07-11 for oversize metal wood with power shaft.
This patent grant is currently assigned to Vardon Golf Company, Inc.. Invention is credited to Dillis V. Allen.
United States Patent |
RE39,178 |
Allen |
July 11, 2006 |
Oversize metal wood with power shaft
Abstract
A wood-type golf club having an enlarged club head in the range
of 250 to 300 cm..sup.3 constructed of a material lighter than
steel to maintain the total club head weight within normal limits
including the weight of novel power shaft according to the present
invention. The club head, without the power shaft, is approximately
175 gms. and the power shaft weighs approximately 25 gms., so the
total club head weight is approximately 200 gms. and within normal
limits. The power shaft, integral with the rear of the ball
striking face wall at its forward end and integral or cast into the
rear of the club head at its rear end, while reinforcing the ball
striking face wall, increases the resonant frequency of the face
wall to synchronize face wall rebound to the player's swing speed.
Face wall resonant frequency is varied by changing the size and
weight of the power shaft.
Inventors: |
Allen; Dillis V. (Elgin,
IL) |
Assignee: |
Vardon Golf Company, Inc.
(Schaumburg, IL)
|
Family
ID: |
25330488 |
Appl.
No.: |
09/567,180 |
Filed: |
May 5, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
08859282 |
May 19, 1997 |
05873791 |
Feb 23, 1999 |
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Current U.S.
Class: |
473/287; 473/332;
473/346; 473/350; 473/336; 473/309; 473/291 |
Current CPC
Class: |
A63B
53/04 (20130101); A63B 53/0466 (20130101); A63B
53/0454 (20200801); A63B 53/0433 (20200801); A63B
60/0081 (20200801); A63B 2209/00 (20130101); A63B
53/0458 (20200801); A63B 53/0412 (20200801); A63B
53/0416 (20200801); A63B 53/06 (20130101); A63B
53/0408 (20200801); A63B 53/045 (20200801) |
Current International
Class: |
A63B
53/04 (20060101); A63B 53/08 (20060101) |
Field of
Search: |
;473/288,305,336,311,346,345,350,332,309,337,287,290,291,342 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Blau; Stephen
Attorney, Agent or Firm: Allen, Esq.; Dillis V.
Claims
I claim:
1. A high impact golf club for compromising perimeter weighting and
ball impact force, comprising: a golf clubhead, a shaft connected
to the golf clubhead, said golf clubhead including a metallic alloy
body having a ball striking face wall, a top wall extending
rearwardly from the face wall, a toe wall extending rearwardly from
the face wall, a heel wall extending rearwardly from the face wall,
a hosel for receiving the shaft extending into the body, all of
said walls being substantially thinner in thickness than length to
define a perimeter weighted clubhead, and means to increase the
rigidity of, to increase the natural frequency of, and to transfer
head weight to the ball striking face wall including a narrow power
member constructed of a metallic alloy, and extending generally
rearwardly therein, said power member being integrally connected to
the clubhead at a rear portion thereof and integrally connected at
a forward end thereof to the ball striking area of the face wall,
an annular retainer formed integrally with and projecting a
substantial distance rearwardly from the ball striking face wall,
said narrow power member being seated within the retainer, and
means to integrally join the forward end of the power shaft to the
retainer.
2. A high impact golf club for compromising perimeter weighting and
ball impact force as defined in claim 1, wherein a weldment
connects the forward end of the power member to the retainer.
3. A high impact golf club for compromising perimeter weighting and
ball impact force as defined in claim 1, including a second
retainer formed integrally with the rear portion and receiving the
power member, said first and second retainers interfering with
insertion of the power member therein, said rear portion of the
body being formed separately from a front portion including the
face wall, and a weldment connecting the rear portion of the body
to the front portion after the power member is inserted into the
first and second retainers.
4. A high impact golf club for compromising perimeter weighting and
ball impact force as defined in claim 3, wherein a first weldment
connects the first retainer to the power member and a second
weldment connects the second retainer to the power member.
5. A high impact golf club for compromising perimeter weighting and
ball impact force as defined in claim 1, wherein the clubhead body
weight is in the range of 150 to 180 gms. and the power member is
in the range of 10 to 60 gms with a combined weight of less than
210 g.
6. A high impact golf club for compromising perimeter weighting and
ball impact force as defined in claim 1, wherein the clubhead body
weight is approximately 175 gms. and the power member weight is
approximately 25 gms.
7. A line of high impact golf clubs for compromising perimeter
weighting and ball impact force that customizes the clubs to the
golfer's swing speed, comprising: a plurality of clubs including at
least one high swing speed club and one low swing speed club
including a plurality of golf clubheads .[.all having the same size
and outer shape.]. , a shaft connected to the golf clubheads, said
golf clubheads including a relatively high modulus metallic alloy
body having a ball striking face wall, a top wall extending
rearwardly from the face wall, a toe wall extending rearwardly from
the face wall, a heel wall extending rearwardly from the face wall,
a hosel for receiving the shaft extending into the body, all of
said walls being substantially thinner in thickness than length to
define a perimeter weighted clubhead, and means for changing the
rigidity of, and means to increase the frequency of, and to
transfer head weight to the ball striking face wall from one club
in the line to another club in the line including a plurality of
narrow power members one in each of the clubheads for varying swing
speeds including first power members to provide a fixed,
non-adjustable after assembly high modulus of elasticity face wall
for the high swing speed club and second power members to provide a
lower fixed, non-adjustable after assembly modulus of elasticity
face wall for the lower swing speed club.
8. A line of high impact golf clubs for compromising perimeter
weighting and ball impact force, comprising: a plurality of golf
clubheads, a shaft connected to the golf clubheads, said golf
clubheads including a relatively high modulus metallic alloy body
having a ball striking face wall, a top wall extending rearwardly
from the face wall, a toe wall extending rearwardly from the face
wall, a heel wall extending rearwardly from the face wall, a hosel
for receiving the shaft extending into the body, all of said walls
being substantially thinner in thickness than length to define a
perimeter weighted clubhead, and means to increase the rigidity of,
and means to increase the natural frequency of, and to transfer
head weight to the ball striking face wall including a plurality of
interchangeable before assembly narrow power members for varying
swing speeds including first power members to provide a high
modulus of elasticity face wall for the high speed swing and second
power members to provide a lower modulus of elasticity face wall
for the lower speed swing, said first and second power members
being annular in configuration and the first power members have a
heavier wall thickness than the second power members.
9. A high impact golf club for compromising perimeter weighting and
ball impact force, comprising: a golf clubhead, a shaft connected
to the golf clubhead, said golf clubhead including a metallic alloy
body having a ball striking face wall, a top wall extending
rearwardly from the face wall, a toe wall extending rearwardly from
the face wall, a heel wall extending rearwardly from the face wall,
a hosel for receiving the shaft extending into the body, all of
said walls being substantially thinner in thickness than length to
define a perimeter weighted clubhead, said ball striking face wall
having a ball striking central area, and means to transfer force
from the head directly to the ball striking central area including
a power member extending rearwardly from the face wall to a rear
portion of the clubhead, a retainer for the power member on the
face wall behind the ball striking central area, a second retainer
for the power member in the rear portion of the clubhead, said
first retainer being annular and projecting a substantial distance
rearwardly from the face wall, said first and second retainers and
the power member being constructed of substantially similar
weldable metal alloys, and a weldment between the first retainer
and the power member and a weldment between the second retainer and
the power member, whereby heat distortion of the face wall and rear
portion of the clubhead is minimized.
10. A high impact golf club for compromising perimeter weighting
and ball impact force as defined in claim 9, including said first
and second retainers being spaced apart a distance less than the
length of the power member.
11. A high impact golf club for compromising perimeter weighting
and ball impact force, comprising: a golf clubhead, a shaft
connected to the golf clubhead, said golf clubhead including a
metallic alloy body having a ball striking face wall, a top wall
extending rearwardly from the face wall, a toe wall extending
rearwardly from the face wall, a heel wall extending rearwardly
from the face wall, a hosel for receiving the shaft extending into
the body, all of said walls being substantially thinner in
thickness than length to define a perimeter weighted clubhead, said
ball striking face wall having a ball striking central area, and
means to transfer force from the head directly to the ball striking
central area including a power member extending rearwardly from the
face wall to a rear portion of the clubhead, a retainer for the
power member on the face wall behind the ball striking central
area, said retainer being annular and formed integrally with the
face wall and protecting a substantial distance rearwardly from the
face wall, and a second retainer for the power member in a rear
portion of the clubhead, the first and second retainers and the
power member being constructed of substantially similar weldable
metal alloys, and a weldment between the first retainer and the
power member and a weldment between the second retainer and the
power member, whereby heat distortion of the face wall and rear
portion of the clubhead is minimized.
12. A high volume metal alloy clubhead comprising: a clubhead body
constructed of a high titanium alloy substantially lighter than
ferrous alloys having a weight in the range of 150 to 180 gms, and
a volume in the range of 250 to 300 cm..sup.3, said clubhead body
being oversized and including at least a face wall, a toe wall, a
heel wall, a top wall and a hosel, all being relatively thin
compared to their extent, said heel wall, toe wall and top wall all
being connected to the front wall at the perimeter of the front
wall so the clubhead body is perimeter weighted, and means for
transferring a portion of the body weight behind a ball striking
area of the face wall including a power member fixed at one end to
a rear portion of the body and at its other end to the face wall,
the mass of the power member being selected so the total weight of
the clubhead is in the range of 190 to 210 gms., whereby the
light-weight body enables the clubhead to be oversized while
leaving a high percentage of total weight for the power member.
13. A metal alloy clubhead as defined in claim 12, wherein the
power member is formed integrally with the face wall at one end and
integrally with the rear portion of the clubhead at its other end,
said power tube having a weight at least 20 percent of total
clubhead weight to concentrate a greater weight directly behind the
ball striking area.
14. A line of golf club woods designed for both lower swing speeds
in the range of 60 to 85 mph and high swing speeds in the range of
85 to 110 mph, comprising: a plurality of identical clubhead bodies
having hosels, a plurality of shafts connectable to the hosels in
the bodies to form golf clubs, said clubhead bodies including at
least a face wall, a top wall, a toe wall and a heel wall each
being relatively thin to their extent, said top wall, toe wall and
heel wall being connected to the perimeter of the face wall so the
clubhead bodies are perimeter weighted to enlarge the sweet spot
and effective hitting area on the face wall, and means to vary the
resonant frequency of the face wall to provide higher resonant
frequency golf clubs for the higher swing speeds and to provide
lower resonant frequency golf clubs for the lower swing speeds
including a plurality of interchangeable power members connectable
between the rear of the face wall and a rear portion of the
clubhead bodies, said power members including power members having
a lower thickness for the lower resonant frequency golf clubs and
including power members having a relatively higher thickness for
the higher resonant frequency golf clubs.
15. A line of golf club woods as defined in claim 14, and means to
maintain the weights of the power members substantially constant
while varying the natural frequency of the face wall including a
plurality of power members, some having relatively thin wall
thickness and some having relatively heavy wall thickness, and
discrete weight means on the power members to equate the weight of
the thin wall thickness power members to the relatively heavy wall
thickness power members.
16. A line of golf club woods as defined in claim 14, wherein the
clubhead bodies have the same weight in the range of 150 to 180
gms. each.
17. A perimeter weighted wood golf club, comprising: a clubhead
including at least a face wall, a top wall, a toe wall, and a heel
wall, each of the walls being relatively thin in thickness compared
to the extent, said top wall, toe wall and heel wall all connected
to the perimeter of the face wall so the clubhead is perimeter
weighted, a hosel in the clubhead for receiving a shaft, a shaft in
the hosel, and means for reducing the weight of the hosel so the
saved weight can be distributed more beneficially in the clubhead
including the hosel being defined by a short annular segment in the
top wall having an axis coincident with the desired lie of the
clubhead, a second short annular segment in a lower portion of the
clubhead having an axis coincident with the axis of the first
annular segment, said first and second annular segments being
spaced apart at least 0.500 inches, and means for bonding the tip
end of the shaft in the first and second annular segments including
a sleeve surrounding the shaft between the hosel segments, said
sleeve being bonded at one end to one hosel segment and bonded at
another end to the other hosel segment.
18. A method of fixing a shaft into a golf clubhead having at least
a face wall, a top wall, a toe wall, and a heel wall, each of the
walls being relatively thin in thickness compared to the extent,
said top wall, toe wall and heel wall all connected to the
perimeter of the face wall so the clubhead is perimeter weighted, a
hosel in the clubhead for receiving a shaft, a shaft in the hosel,
and means for reducing the weight of the hosel so the saved weight
can be distributed more beneficially in the clubhead including the
hosel being defined by a short annular segment in the top wall
having an axis coincident with the descend lie of the clubhead, a
second short annular segment in a lower portion of the clubhead
having an axis coincident with the axis of the first annular
segment, said first and second annular segments being spaced apart
at least 0.500 inches, including the steps of applying a bonding
agent to the tip end of the shaft, and inserting the tip end of the
shaft first through the first segment and then into the second
segment while rotating and orienting the shaft so the bonding agent
is layered on the shaft between the first and second segments so
the bonding layer is bonded to both segments and the shaft to
reinforce the shaft.
19. A line of golf club woods designed for both lower swing speeds
in the range of 60 to 85 mph and high swing speeds in the range of
85 to 110 mph, comprising: a plurality of clubhead bodies having
hosels, a plurality of shafts connectable to the hosels in the
bodies to form golf clubs, said clubhead bodies including at least
a face wall, a top wall, a toe wall and a heel wall each being
relatively thin to their extent, said top wall, toe wall and heel
wall being connected to the perimeter of the face wall so the
clubhead bodies are perimeter weighted to enlarge the sweet spot
and effective hitting area on the face wall, and means to vary the
resonant frequency of the face wall to provide higher resonant
frequency golf clubs for the higher swing speeds and to provide
lower resonant frequency golf clubs for the lower swing speeds
including a plurality of power member connectable between the rear
of the face wall and a rear portion of the clubhead bodies, said
power members including power members having a lower frequency for
the lower resonant frequency golf clubs and including power members
having a relatively higher frequency for the higher resonant
frequency golf clubs, and means to maintain the weights of the
power members substantially constant while varying the natural
frequency of the face wall including a plurality of power members,
some having relatively thin wall thickness and some having
relatively heavy wall thickness, and discrete weight means on the
power members to equate the weight of the thin wall thickness power
members to the relatively heavy wall thickness power members, the
clubhead bodies having the same weight in the range of 150 to 180
gms. each.
20. A high impact golf club for compromising perimeter weighting
and ball impact force, comprising: a golf clubhead, a shaft
connected to the golf clubhead, said golf clubhead including a
metallic alloy body having a ball striking face wall, a top wall
extending rearwardly from the face wall, a toe wall extending
rearwardly from the face wall, a heel wall extending rearwardly
from the face wall, a hosel for receiving the shaft extending into
the body, all of said walls being substantially thinner in
thickness than length to define a perimeter weighted clubhead, said
face wall having a ball striking area and a rear surface, and means
for transferring force from the body to the ball striking area,
increasing the naturally frequency of the face wall while
maintaining acceptable overall clubhead weight including a power
member fixed at one end to the rear surface of the first wall at
the ball striking area and fixed at its other end to a rear portion
of the clubhead, a weight receptacle on the power member, and a
discrete weight connected into the receptacle to adjust overall
clubhead weight to the desired value without substantially varying
the natural frequency of the face wall.
21. A high impact golf club for compromising perimeter weighting
and ball impact force as defined in claim 18, wherein the power
member is tubular in configuration, said receptacle on the power
member including an annular threaded boss integrally formed with
the tubular power member, said discrete weight being generally
circular and having outer threads on the power member annular
threaded boss.
22. A jumbo metal wood clubhead constructed of a lightweight hard
alloy, comprising: a clubhead constructed of a high titanium alloy
having a face wall, a top wall, a toe wall and a heel wall, said
clubhead having a weight in the range of 150 to 180 g., a hosel
projecting upwardly from the clubhead, said clubhead being
constructed of a hard metal alloy having a modulus of elasticity
substantially less than steel alloys, said clubhead having an outer
volume of at least 250 cm.sup.3 and wall thickness less than about
0.150 inches, and means to reinforce the face wall including a high
titanium alloy power shaft integral with the face wall at one end
and integral with a rear portion of the clubhead at its rear end,
said power shaft having a weight so the combined weight of the
power shaft and club-head is less than 210 g.
23. A line of golf clubs designed to customize the clubs to the
players swing speeds, comprising: a plurality of clubs including at
least one high swing speed club and one low swing speed club
including a plurality of clubhead bodies .[.all having the same
size and outer shape.]. having hosels and ball striking face walls,
a plurality of shafts attached to the hosels in the bodies to form
golf clubs, said bodies having a perimeter wall about the face
wall, and means to change the characteristics of the clubhead
bodies from one clubhead body in the line to another clubhead body
in the line depending upon the players swing speed including means
to change the modulus of elasticity of the face walls in the line
from one clubhead body in the line to another clubhead body in line
to provide a fixed, non-adjustable after assembly high modulus of
elasticity face wall in some of the clubhead bodies in the line for
the higher swing speed player without changing the size or outer
shape of the clubhead bodies, and also to provide a relatively
lower fixed, non-adjustable after assembly modulus of elasticity
face wall in others of the clubhead bodies in the line for the
lower swing speed player without changing the size or outer shape
of the clubhead bodies.
24. A line of golf clubs as defined in claim 23, wherein the means
to vary the modulus of elasticity of the face walls in the line
includes a plurality of interchangeable before assembly power
members connectable between the rear of the face wall and a rear
portion of the clubhead bodies.
25. A line of golf clubs designed to customize the clubs to the
players swing speeds, comprising: a plurality of clubs including at
least one high swing speed club and one low swing speed club
including a plurality of clubhead bodies .[.all having the size and
outer shape.]. having hosels and ball striking face walls, a
plurality of shafts attached to the hosels in the bodies to form
golf clubs, said bodies having a perimeter wall about the face
wall, and means to change the characteristics of the clubhead
bodies from one club in the line to another club in the line
depending upon the players swing speed including means to change
the stiffness of the face walls in the line to provide a fixed,
non-adjustable after assembly high stiffness face wall in some of
the clubhead bodies in the line without changing the clubhead body
size or outer shape for the higher swing speed player and a
relatively lower fixed, non-adjustable after assembly stiffness
face wall in others of the clubhead bodies in the line for the
lower swing speed player without changing the clubhead body size or
outer shape.
26. A line of golf clubs as defined in claim 25, wherein the means
to vary the stiffness of the face walls includes means for varying
the stiffness of the face wall without changing the weight of the
clubhead bodies.
Description
BACKGROUND OF THE PRESENT INVENTION
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.
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.
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.
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.
In an iron club, perimeter weighting is an easier task because for
a given swing weight, iron club heads can be considerably heavier
than metal woods because the iron shafts are shorter. So attempts
to increase perimeter weighting over the past decade have been more
successful in irons than "wooden" club heads. Since the innovation
of investment casting in iron technology in the late 1960s, this
technique has been utilized to increase the perimeter weighting of
the club head or more particularly a redistribution of the weight
of the head itself away from the hitting area to the perimeter
around the hitting area, usually by providing a perimeter wall
extending rearwardly from the face that results in a rear cavity
behind the ball striking area. Such a club head configuration has
been found over the last two plus decades to enable the average
golfer, as well as the professional, to realize a more forgiving
hitting area and by that we mean that somewhat off-center hits from
the geometric center of the face of the club results in shots
substantially the same as those hits on the center of the club.
Today it is not uncommon to find a majority of professional golfers
playing in any tournament with investment cast perimeter weighted
irons confirming the validity of this perimeter weighting
technology.
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.
In the Raymont, U.S. Pat. No. 3,847,399 issued Nov. 12, 1974,
assigned to the assignee of the present invention, a system is
disclosed for increasing the perimeter weighting effect of a golf
club by a pattern of reinforcing elements in the ball striking area
that permits the ball striking area to be lighter than normal,
enabling the designer to utilize that weight saved on the forward
face by adding it to the perimeter wall and thereby enhancing
perimeter weighting.
This technique devised by Mr. Raymont was adopted in the late 1980s
by many tool designers of investment cast metal woods to increase
the strength of the forward face of the metal woods to maintain the
requirement for total overall head weight and to redistribute the
weight to the relatively thin investment cast perimeter walls
permitting these walls to not only have greater structural
integrity and provide easier molding and less rejects, but also to
enhance the perimeter weighting of these metal woods.
Another problem addressed by the present invention is the
achievement of increasing the benefits of perimeter weighting by
simply adding weight to the perimeter of the club head itself. This
technique, of course, has found considerable success in low impact
club heads such as putters, where overall club head weight is in no
way critical, and in fact in many low impact clubs that have found
considerable commercial success, the club heads weigh many times
that of metal wood heads, sometimes three or four times as
heavy.
To this date, however, increased perimeter weighting has not been
found easy because of the weight and impact strength requirements
in metal woods. An understanding of perimeter weighting must
necessarily include a discussion of the parameter radius of
gyration. The radius of gyration in a golf club head is defined as
the radius from the geometric or ball striking axis of the club
along the club face to points of club head mass under
consideration. Thus, in effect the radius of gyration is the moment
arm or torquing arm for a given mass under consideration about the
ball striking point. The total moments acting on the ball during
impact is defined as the sum of the individual masses multiplied by
their moment arms or "radii of gyration". And this sum of the
moments can be increased then by either increasing the length of
the individual moment arms or by increasing the mass or face acting
at that moment arm or combinations of the two.
Since it is not practical, except for the techniques discussed in
the above Raymont and Allen patents, to add weight to the perimeter
wall because of the weight limitations of metal woods and
particularly the driving woods, one alternative is to increase the
moment arm or radius of gyration. This explains the popularity of
today's "jumbo" woods although many of such woods do not have
enlarged faces because of the requirement for structural integrity
in the front face.
In the Allen, U.S. Pat. No. 5,397,126, an improved metal wood golf
club is provided having an enlarged or "jumbo" metal club head with
a crowned top wall extending rearwardly from a ball striking face
wall, a toe wall, and a heel wall also projecting rearwardly from
the face wall--but the club head has no conventional sole
plate.
The toe wall and the heel wall are enclosed by the top wall and a
pair of spaced generally vertical weighting walls integral with and
extending rearwardly from the face wall. The two areas enclosed by
the top wall, heel and toe walls, and weight walls are hollow to
achieve the desired head weight and the area between the walls is
opened, and the weight of the sole plate that normally encloses the
area is redistributed to the weight wall to achieve true heel and
toe weighting.
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
several manufacturers switching from stainless steel to aluminum
and titanium alloys, which are of course lighter, to enlarge the
head as well as the face.
It is possible to enlarge not only the overall head but the face as
well and at the same time increase the heel toe weighting of the
head. Basically, these objectives can be achieved by a combination
of a honeycomb reinforcing network formed integrally on the rear
surface of the forward wall between the weighting walls and a
redistribution of the weight of the conventional sole plate, which
is eliminated in this design, and the weight saved on the thinner
than normal face wall to the weighting walls themselves. The two
enclosed areas defined by the top wall, heel and toe walls, and
weighting walls are hollow, but they may be foam-filled if desired
to reduce ball impact noise levels.
It has also been suggested in the past that various rods and shafts
be cast or attached into the club head for the purpose of
rigidifying the forward face wall. However, to the present date,
such designs have not achieved any significant commercial
success.
The first problem is that, while some of the prior art suggests
casting the rods with the forward face, as a practical matter this
has never been achieved because of the extreme difficulty in
removing the core pieces around the shaft due to interference with
the walls of the club head.
A second problem that is not addressed in this prior art is that in
order to be effective in reinforcing the front face, the shafts
need to be integrated into the club head. The shaft must also have
a weight in the range of 20 to 30 gms. If one simply adds 20 to 30
gram element to a 200 gm. head, the resulting weight of 220 to 230
gms. is excessive and will result in a swing weight far higher than
acceptable to the present day average golfer.
An additional problem in many of these prior rigidifying elements
is that they are constructed of a low modulus material such as
plastic or graphite compositions. These materials do not
significantly increase the resonant frequency or the rebound of the
face wall. Ideally, the rebound of the face wall; that is, the
return of the face wall to its relaxed configuration, should occur
at approximately the time the ball exits the face wall contact. In
this way the rebound of the face wall assists in propelling the
ball from the club face. If rebound occurs after the ball exits the
face wall, the benefits of this effect are completely lost. None of
the prior art dealing with these reinforcing elements suggests
utilizing this technique for matching face wall rebound with ball
exit from the face wall.
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.
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.
The following patents or specifications disclose club heads
containing face reinforcing elements:
FOREIGN PATENTS
British Patent Specification, No. 398,643, to Squire, issued Sep.
21, 1933;
UNITED STATES PATENTS
Clark, No. 769,939, issued Sep. 13, 1904
Palmer, No. 1,167,106, issued Jan. 4, 1916
Barnes, No. 1,546,612, issued Jul. 21, 1925
Drevitson, No. 1,678,637, issued Jul. 31, 1928
Weiskoff, No. 1,907,134, issued May 2, 1933
Schaffer, No. 2,460,435, issued Feb. 1, 1949
Chancellor, No. 3,589,731, issued Jun. 29, 1971
Glover, No. 3,692,306, issued Sep. 19, 1972
Zebelean, No. 4,214,754, issued Jul. 29, 1980
Yamada, No. 4,535,990, issued Aug. 20, 1985
Chen, et al., No. 4,681,321, issued Jul. 21, 1987
Kobayashi, No. 4,732,389, issued Mar. 22, 1988
Shearer, No. 4,944,515, issued Jul. 31, 1990
Shiotani, et al., No. 4,988,104, issued Jan. 29, 1991
Ducios, No. 5,176,383, issued Jan. 5, 1993
Atkins, No. 5,464,211, issued Nov. 7, 1995
Rigal, et al., No. 5,547,427, issued Aug. 20, 1996
In the Squire British Specification 398,643, the reinforcing rods
10 and 18 are primarily for the purpose of reducing ringing in the
face. Squire makes no attempt to maintain head weight within
acceptable limits and is completely silent on how the rod 10 can be
cast inside the head while removing the core pieces therefrom.
Squire is also silent on the rebound or resonant frequency on the
head.
The Clark, U.S. Pat. No. 769,939, shows a movable rod that assists
in propelling the ball from the club face.
The Palmer, U.S. Pat. No. 1,167,106 shows a weighting element that
does not extend completely through the club head.
The Barnes, U.S. Pat. No. 1,546,612, shows rods 13 and 14 extending
into the club head, but these rods are for attachment purposes of
the face 10 and the club is not a perimeter weighted club.
The Drevitson, U.S. Pat. No. 1,678,637, shows reinforcing
partitions 55, but these are not concentrated directly behind the
ball striking area, and thus, while rigidifying the face, do not
concentrate mass transfer directly to the ball.
The Weiskoff, U.S. Pat. No. 1,907,134, shows a reinforcing member
near the center of the club face, but such is not concentrated
specifically in the ball striking area and is not a high modulus
material.
The Schaffer, U.S. Pat. No. 2,460,435, shows a labyrinth of webs
molded in the club head, but the club head is not a high modulus
material, nor is the club face and the core 11 is aluminum and not
constructed of the same material as the club head.
The Chancellor, U.S. Pat. No. 3,589,731, shows a movable weight
between the back and the front of the club that allegedly corrects
hooking and slicing.
The Glover, U.S. Pat. No. 3,692,306, shows a weight port integral
with the club face in FIG. 6, but Glover's club head is a low
modulus resin and is not perimeter weighted.
The Zebelean, U.S. Pat. No. 4,214,754, shows support members 32 in
FIG. 10, but they are not connected to the face nor are they
concentrated behind the sweet spot.
The Yamada, U.S. Pat. No. 4,535,990, shows a shaft between the rear
of the face wall and a back portion of the club, but the Yamada
club head is not a high modulus material, and the patent is silent
as to how the reinforcement member 31 is connected into the club
head cavity.
The Chen, et al., U.S. Pat. No. 4,681,321, shows webs 31 molded
inside the club head, but both the club head and the webs are low
modulus materials.
The Kabayashi, U.S. Pat. No. 4,732,389, shows a brass plate and a
rod that engage the rear of the ball striking face, but the patent
is silent as to how it is attached to the face and the club head is
solid wood and not a perimeter weighted club head.
The Shearer, U.S. Pat. No. 4,944,515, shows a shaft 24 either cast
or attached inside the club head. The Sheer patent is silent as to
how the shaft could be cast in the club head and in the alternative
suggests that it be fixed in after the club head is made, the
patent is silent as to how it might be fixed inside.
The Shiotani, et al., U.S. Pat. No. 4,988,104, shows an insert 15
that is insert molded inside the golf club head, but the club head
is a resin type low modulus material, and there is no specific
attachment of the insert into the head other than that which
results from the insert molding process.
The Ducios, U.S. Pat. No. 5,176,383, discloses a low modulus
graphite head having a rod formed on the rear of the ball striking
face. The low modulus head provides the Ducios club with minimal
perimeter weighting.
The Atkins, U.S. Pat. No. 5,464,211, shows a plate 30 that is
threaded from the rear of the club against the forward face which
he refers to as a "jack screw". The plate 30 is epoxied to the rear
of the face wall and such a design will fail under the extreme high
impact loadings of a 150 ft./sec. impact with a golf ball.
The Rigal, et al., U.S. Pat. No. 5,547,427, shows partitions. In
the FIG. 9 embodiment, the rod 74 is placed in tension which
detracts from rigidifying the front face. In the FIG. 10
embodiment, the rod 23 is not integral with the front face.
A further principle problem addressed in the present invention has
resulted from the use of light-weight alloys to "jumbo" or
oversized metal woods that are particularly popular is today's
golfing market. As noted above, these use light-weight metals such
as high titanium alloys that permit the clubhead to be made larger,
providing increased perimeter weighting and an easier to hit larger
sweet spot. However, there is a trade-off to this large sweet spot
and that is a diminution in ball distance travel or in short, the
ball does not travel as far as it does with smaller stainless steel
heads, which concentrate more mass behind the ball. This in part
explains why professionals on the regular tour rarely use very
large titanium clubheads.
This diminution in ball distance in jumbo titanium alloys, or other
light-weight alloy heads, is believed caused by two factors. First,
the very large clubheads spread the perimeter wall support points
from the ball striking area, causing the face to flex more than
smaller heads resulting in a badly delayed rebound of the face.
Secondly, while titanium is a hard material, it has a modulus of
elasticity less than half that of ferrous alloys.
It should be noted that today's high titanium alloy jumbo metal
wood heads having volumes in the range of 250 to 300 cm..sup.3,
have relatively thin wall thickness, less than 0.125, and in some
cases substantially less than 0.125 inches, which exacerbates the
problem of face flexure and slow face rebound. The decrease in ball
distance travel in these clubs is believed due in part to an
incomplete face recovery during ball impact. That is, the club
bends inwardly at ball impact and then returns to its normal
relaxed position. The rebound of the club face, or its returns to
its relaxed position, should assist in propelling the ball from the
clubface. In these high titanium jumbo clubheads however, the face
wall does not fully recover until after the ball leaves the club
face, thereby dissipating as waste a portion of the clubhead
energy.
If one can imagine a fixed flat board supported at points two feet
apart and second board supported at points 10 feet apart, both with
a 200 lb. weight in the middle of the board, the second board will
bend a great amount more. This is what causes in part the greater
face flexure in the jumbo metal woods.
And while titanium is perceived as an extremely strong material, it
is only strong in the sense that it has a high surface hardness.
Actually, its resistance to flexure; i.e., its modulus of
elasticity, is less than half that of the ferrous alloys such as
stainless steel. Thus, in addition to the widely spaced supports
described above, increased face flexure of these clubheads at ball
impact attributed to its modulus, both contribute to a late face
recovery.
Other objects and advantages of the present invention will appear
more clearly from the following detailed description.
SUMMARY OF THE PRESENT INVENTION
According to the present invention, a high modulus golf club head
of the "wood" type is provided with a power shaft, a rod for
increasing the resonant frequency and decreasing the rebound time
of the face, integral at its forward end with the ball striking
wall behind the sweet spot and integral with a rear portion of the
club head at its rear end. While others have attempted supports for
other purposes such as face reinforcement and club sound or feel,
they have not been successful because these clubs are either not
possible to manufacture, or will fail under the rigors of a 100 to
150 ft./sec. impact velocity against a golf ball.
A primary provision of the present invention is a jumbo clubhead in
the range of 250 to 300 cm..sup.3 constructed of a hard,
light-weight alloy such as titanium or beryllium, with an integral
power shaft extending from behind the club face sweet spot to a
rear portion of the club head.
Toward these ends, the power shaft according to the present
invention is constructed of a metal alloy substantially similar to
the metal alloy of the club head so it may be welded or fixed
integrally to the sweet spot on the rear of the face wall and cast
welded or fixed integrally to a rear portion of the club head at
its rear end. While welding similar metals is certainly not a new
concept, it is not possible to weld, for example, a 0.625 inch
diameter shaft with a 0.035 to 0.049 inch wall thickness directly
to the club head face wall and rear wall because the face wall and
rear wall, because of their large areas, require higher heating and
welding temperatures resulting in heat distortion of the face wall
and rear clubhead.
To obviate this problem, the face wall sweet spot and the rear club
head portion have cast in annular retainer walls to which the power
shaft is welded. These retainers buff the heat sink effect of the
face wall and club head portion and minimize heat distortion in
these surfaces during welding.
The power shaft according to the present invention is a compromise
between club head designs to enhance perimeter weighting and
increase the sweet spot area, and the ball distance producing
designs that concentrate more mass directly behind the ball at
impact. Larger club heads that are constructed of thin or light
walls are far easier for the average golfer to hit consistently
with off center hits because the mass or walls of the club head are
spread out further from the geometric center or ball striking area
on the club head wall face. This design increases what is termed
the radius of gyration of the club head by golf club engineers. In
short, this concept tells the engineers that the further one
defines the walls of the club head away from the center of the
face, the larger the effective hitting area or sweet spot on the
club face. This makes this design approach extremely attractive to
the average golfer, but not necessarily the stronger and low
handicap players because there is a trade off with ball distance,
which decreases generally speaking, with larger perimeter weighted
heads.
Why? Because in order to keep total club head weight in a driver,
for example at about 195 to 205 grams and at the same time make an
oversized club head to increase perimeter weighting, the club face
must be relatively thin and since it is larger than standard, it
deforms more upon impact which, absent frequency matching
techniques, will decrease ball distance travel.
Hence, the compromise between increased radius of gyration and
increased ball distance to which the present invention is directed.
The ideal long driving club is not perimeter weighted, it is
instead a solid brass rod having the diameter of a U.S. quarter and
a length of four inches with a shaft aligned so the long driver
hits the ball with one end of the brass rod. This design
concentrates 100% of the mass of the club head on the flattened
rear surface of the ball at impact.
This is the ideal design for ball distance or the long ball, but
even long driving professionals would not use such a club in
competition because even with their skills slightly off center
hits, on the order of 1/8'', produce poor results. But it should be
noted here that most professional long drivers do use relatively
small heads to concentrate mass more closely to the center of the
ball.
According to the present invention, this compromise is achieved by
combining an oversize high modulus perimeter weighted metal wood of
light weight material with an integrally formed power shaft of
similar material. It is possible to form this design in stainless
steel with a density of about 8 grams per cm.sup.3 but is very
difficult to maintain total clubhead weight under 225 grams if
volume exceeds 220 cm..sup.3, which is somewhat above the ideal for
the average golfer; e.g., 200 grams. A stainless steel club has
been produced, according to the principles of the present
invention, with 208 grams in stainless steel, a volume of about 230
cm.sup.3 and a power shaft 21/8'' long, 0.625'' OD and with a
0.035'' wall thickness.
There is a distinct advantage in embodying this design in a high
titanium alloy instead of stainless steel which has a weight about
60% of stainless, on the order of 4.54 grams per cm.sup.3, because
the head can be made larger than 230 cms.sup.3, and the power shaft
can be made heavier than in stainless while maintaining total club
head weight around 200 grams. Hence, the present design is
particularly advantageous to club heads cast or forged in high
titanium or similar alloys.
Another important aspect of the present invention is the
customizing of the golf club to the swing speed of the golfer.
Golfers swing speed differ radically from about 88 ft/sec. up to as
much as 180/ft/sec.(123 mph). The club face at impact becomes
concave and before or after the ball leaves the face, the face
rebounds to its natural shape. The time the ball remains on the
face is surprisingly about the same for the slow swings and the
fast, but the harder swinger will compress the ball further.
Ideally, for both the fast and slow swinger, the face will rebound
precisely as the ball is exiting the face to enhance ball exit
velocity. But to do this, bearing in mind time of impact, about 5-7
milli/sec., is about the same for all swing speeds, the face must
recover at a faster rate for the high speed swing because it has a
greater face deflection. To achieve this, the present line of woods
gives the higher speed swinger a progressively higher face wall
resonant frequency than the lower speed swing. Numerous studies
have been made analoging the natural or resonant frequencies of
bodies to the rebound of the bodies after bending or deformation
and those have been adopted here. But it should be noted however,
the natural frequency of all linear structures increases with
increasing stiffness and decreases with increasing mass.
In a free body system, the natural frequency of the system f is
equal to 1/2.sub..pi. (K)/M.sup.1/2 where f is in cycle per unit of
time, of a beam pinned at both ends and center loaded, as the face
of a golf club, the spring constant K; i.e., force/unit deflection
at point of L and is equal to .times. .times. ##EQU00001## where E
is the modulus of elasticity of the material, I is the moment of
inertia, and L is the unsupported length.
While titanium is a very hard material, it has a relatively low
modulus(E) of 16.8 psi.times.10.sup.-6 compared to stainless steel,
which is 30 psi.times.10.sup.-6. And the natural frequency varies
as {square root over (E)} when E is the modulus of elasticity.
Hence, it is when equating the rebound of a titanium face to that
of steel the titanium face must be stiffened significantly more and
in quantified amounts, and the present invention provides the tools
to do that.
As noted above while golfer swing speeds differ greatly, time of
ball impact does not and total clubhead weight stays in the range
of 195 to 205 grams for most all swing speeds. Thus to achieve face
frequency matching to swing speed, the present invention provides a
means to vary face stiffness while maintaining about the same
overall head weight.
Toward this end the face wall is stiffened by selecting a power
shaft of varying wall thickness, which of course are of different
weight, to equate the weights, the rods are provided with
transverse weight ports for high density weights, that yield the
same overall weight to the clubhead but varying stiffness and
natural frequency to the club face. In this way, faster face
rebound is provided for the higher speed golfer and hence slower
face rebound for the slower speed golfer to assure that face
rebound coincides with ball exit event on the club face.
Using these philosophies, a line of relatively high modulus metal
woods has been developed, and while stainless steel can be used,
the choice is lighter weight alloys having a high surface hardness
such as a high titanium or a high beryllium alloy. Utilizing a
single club head body tool(the club head bodies are the same
initially as are their face walls), the system includes a plurality
of interchangeable power shafts providing increasing stiffness and
resonant frequency to the ball striking wall, beginning with this
walled shaft for the slower swinger and progressing to a heavy wall
shaft for maximum stiffness and higher resonant frequency for the
higher swing speed club.
Another important feature of the present invention is a reduced
weight and higher strength hosel that enables the weight saved in
the hosel to be redistributed in the form of greater perimeter
weighting, larger face walls, heavier perimeter wall thickness or
even heavier face wall thickness to improve the integrity of the
face wall.
To achieve this result, the present hosel essentially consists of
two fairly widely spaced annular bosses cast in the clubhead with
the required club head walls and eliminating most of the hosel
extension above the top wall of the club head. This design not only
eliminates the weight of the tubular hosel between these bosses,
but redistributes the club head torque on the shaft because of the
widely spaced bosses compared to the concentrated torque applied to
the shaft by relatively short one-piece hosels. The strength of
this hosel assembly is significantly augmented by the technique of
epoxying the tip end of the shaft, usually fragile graphite, into
these spaced bosses. During assembly of the shaft, the tip end of
the shaft is applied with pre-mixed A and B epoxy completely
coating an annular surface on the tip end of the shaft from the tip
to at least a point spaced from the tip end a distance equal to the
maximum distance between the first and second hosel bosses. By
rotating the epoxied shaft while inserting it into the bosses and
changing orientation of the club while the epoxy begins to set, an
epoxy sleeve can be produced on the portion of the shaft between
the two annular bosses that is also bonded to the bosses to provide
a lighter weighted strong bond between the upper and lower
bosses.
As described above, one of the problems with today's jumbo metal
woods, constructed of these walled hard alloy materials, such as
titanium, is that face rebound or recovery is incomplete as the
ball leaves the club face causing a portion of the head energy to
be dissipated as waste, rather than being impacted to the ball.
This problem is caused by the low modulus of elasticity of titanium
and other materials relative to stainless steel, and the long
unsupported length of the club face in jumbo metal woods.
According to the present invention, the face walls in these
clubheads is caused to fully recover prior to ball impact thereby
imparting more energy to the ball and increasing ball distance
travel. More specifically, one primary object of the present
invention is to provide a jumbo clubhead. In excess of 250
cm.sup.3, constructed of thin walls, less than 0.125'' in
thickness, of a hard alloy with a low modulus relative to steel,
with a power shaft integral with the head, that causes the face
wall to rebound fully at ball impact before the ball leaves the
club face.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective of a golf club according to the present
invention having its shaft truncated;
FIG. 2 is an enlarged top view of the clubhead illustrated in FIG.
1 without any shaft;
FIG. 3 is a left side view of the clubhead illustrated in FIG.
1;
FIG. 4 is a right side view of the clubhead illustrated in FIGS. 1
to 3;
FIG. 5 is a rear view of the clubhead illustrated in FIGS. 1 to
4;
FIG. 6 is a bottom view of the clubhead illustrated in FIGS. 1 to
5;
FIG. 7 is a rear perspective of the clubhead illustrated in FIGS. 1
to 6;
FIG. 8 is a bottom perspective of the clubhead illustrated in FIGS.
1 to 7;
FIG. 9 is a rear view of a sub-assembly of the clubhead illustrated
in FIGS. 1 to 8 with portions of its hosel shown in fragmented
section;
FIG. 10 is a longitudinal section through the clubhead according to
the present invention taken generally along line 10--10 of FIG.
5;
FIG. 11 is a cross-section of the clubhead illustrated in FIGS.
1-10 taken generally along line 11--11 of FIG. 2;
FIG. 12 is a right side top perspective view of the clubhead
sub-assembly illustrated in FIG. 9;
FIG. 13 is a top perspective of a rear portion sub-assembly of the
clubhead illustrated in FIGS. 1 to 8;
FIGS. 14 to 18 are four power shafts according to the present
invention, each providing a different resonant frequency;
FIG. 19 is a rear perspective of a forward subassembly of the
clubhead illustrated in FIGS. 1 to 8 constructed differently than
the sub-assemblies illustrated in FIGS. 9, 12 and 13;
FIG. 20 is a rear perspective of a clubhead rear portion that mates
with the forward clubhead sub-assembly illustrated in FIG. 19,
and;
FIG. 21 is a longitudinal section of the subassemblies illustrated
in FIGS. 19 and 20 taken generally along line 21--21 of FIG.
19.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings and particularly FIGS. 1 to 8, a clubhead
10 is illustrated which takes the general configuration of what is
termed a "metal wood" in the golf industry, and as seen in FIG. 1,
is implanted with a shaft 12 shown only in fragmented form which
carries at its upper end a conventional grip. A golf club as
defined in the present invention includes a clubhead with shaft 12
fixed therein which carries the shown grip at its upper distal
end.
Many of the views in the present drawings including FIGS. 2, 3, 4,
5, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, and 18 are shown
approximately to scale and in fact are about 5 to 10% smaller than
a 1--1 scale.
The clubhead 10 has an included volume of 260 cm..sup.3, but could
range from 230 to 300 cm..sup.3. "Included" volume is defined as
the volume encompassed to the outermost walls of the clubhead that
includes recessed areas that are not actually enclosed by walls
such as a bottom wall cavity.
The clubhead 10 is constructed entirely of a relatively high
modulus castable or forgible metal alloy and is particularly best
embodied in a light-weight hard surfaced alloy such as a high
titanium or beryllium alloy. However, it should be understood that
other alloys, for example, a 17-4 stainless steel alloy, can also
be utilized with some of the features of the present invention, but
the lightweight alloys such as titanium and beryllium, are better
suited to achieve the desired balance between an oversized clubhead
on the order of 250 to 300 cc. combined with the present power
shaft to provide an overall clubhead weight, including the power
shaft, in the range of 190 to 205 gms. This combination is far
easier achieved with the lightweight high hardness alloys such as
titanium and beryllium. Because it is an object of the present
invention to achieve a high resonant frequency ball striking face,
it must be understood that high titanium alloys, for example, have
a relatively low modulus on the order of 14 10.sup.-6 psi compared
to some 30.times.10.sup.-6 psi for the ferrous metal alloys. Since
as noted above the objects of the present invention are achieved by
increasing, and varying, the resonant frequency of the ball
striking face of the clubhead utilizing a series of variably
configured power shafts, it is necessary in the relatively lower
modulus lighter metal alloys that the ball striking face be
stiffened to a somewhat greater extent than is necessary in the
high modulus metal alloys such as stainless steel. While at the
present time the high titanium alloys are preferred by most metal
wood golf club designers over stainless steel alloys, the choice is
somewhat dictated by the fact that high titanium alloys weigh only
60% of the stainless steel alloys, so it is far easier for the
designer to have a greater design flexibility with titanium than
with stainless steel. The trade-off, however, is that very large
golf club heads in titanium or similar material, while providing
excellent perimeter weighting for the high handicap golfer, their
low modulus compared to stainless steel, increases flexure and
lowers the resonant frequency of the front face. So low that the
rebound of the face is significantly delayed until after ball exit
which detracts from maximum ball travel. Ball distance travel in
these extremely oversized heads is also diminished because of a
lack of mass concentration directly behind the hitting area which,
of course, is the antithesis of what many of today's designers are
attempting to achieve with exaggerated perimeter weighting.
As noted above, the present invention has its objective of
providing an oversized head, and at the same time compromising the
effects of perimeter weighting with the present power shaft that is
positioned directly behind the ball impact area on the front face
of the clubhead.
Another advantage in utilizing a light-weight alloy for the head 10
is that it permits a greater concentration of mass in the power
shaft than can be achieved with the higher density alloys. That is,
in a stainless steel head it is difficult to produce an oversized
or jumbo head unless the weight of the power shaft is 10% or less
of the weight of the remaining head; i.e., on the order of 20 gms.
Utilizing a high titanium alloy, however, it is possible to
increase the weight of the power shaft to as high as 25% of the
weight of the remaining head, or on the order of 50 gms. This
provides considerably more design flexibility in power shaft
variations when utilizing high titanium alloys. However, there is a
greater need for a higher weight concentration in the titanium or
light-weight alloy metals simply because the front face modulus is
lower in these clubheads.
Again referring to FIGS. 1 to 8, the present clubhead body 10 is
seen to generally include an open area 11 as seen in FIGS. 5, 6 and
8, in which the cylindrical power shaft or tube 12 is integrally
fixed.
The power shaft 12 is constructed of the same or substantially
similar metal alloys as that of the clubhead 10 because the power
shaft is welded at both its forward and rear end into the clubhead
10 to provide the appropriate structural integrity for not only the
clubhead 10 but for reinforcing the club face and achieving the
desired resonant frequency and rebound of the club face. The term
"integral" as defined herein, includes welding, integral casting
and press fitting. It does not include bonding with epoxy or other
adhesives.
One of the purposes of the power shaft 12 is to vary the resonant
frequency and the rebound of the forward face of the club for the
individual player so club face rebound will apportionately coincide
with the ball exit from the club face and assist in propelling the
ball forwardly.
Clubhead 10 includes a forward ball striking wall 14 having an
extended toe portion 15 and a heel portion 16 that extends
outwardly from a hosel portion 17 in a direction opposite of ball
striking area 19 on the club face. This geometry defines the hosel
17 as being an "inset" hosel in the sense that the axis of the
hosel is inset toward the ball striking area 19 from the heel
portion of the clubhead.
A top wall 20 is formed integrally with the front face and projects
rearwardly and downwardly therefrom as seen clearly in FIG. 3. Top
wall 20 also wraps around the hosel and has a heel portion 21 that
joins with face heel portion 16 on the side of the hosel 17
opposite the ball striking area 19, also in part defining the inset
relationship of the hosel 17.
As seen in FIG. 4, a heel wall 24 is provided joined integrally
with top wall 20 and face wall 24 that has a heel portion 25 that
joins with the face heel portion 16 and the top wall heel portion
21 in a direction opposite hitting area 19 from the axis of hosel
17 to again define the inset relationship. It should be noted at
this point that the walls of the clubhead 10, when constructed of
stainless steel, are on the order of 0.050-0.070 in. in thickness
except face wall 14, which is approximately 0.100 in. underneath
the honeycomb reinforcement network 28 shown in FIG. 5, for
example.
As seen in FIG. 3, a toe wall 28, formed integrally with front wall
14 and top wall 20, wraps around the top wall 20 and connects with
the heel wall 24 with a narrow downwardly depending rear portion 31
shown in FIG. 5, that is integral with top wall 20.
As seen in FIGS. 8 and 9, a toe weight wall 32 is formed integrally
with face wall 14 and top wall 20 and a heel weight wall 33 is
formed integrally with the front wall 14 and the top wall 20. Toe
weight wall 32 is also integrally formed with toe wall 29 while
heel weight wall 33 is also formed integrally with the heel wall
24, thereby defining hollow toe chambers and heel chambers similar
to that described in my U.S. Pat. No. 5,397,126.
The rear surface of the face wall has an integral honeycomb
structure 18 that reinforces and permits the face wall to be formed
considerably thinner than normal.
As seen in FIG. 2, the lateral total length of the clubhead 10 in a
direction perpendicular to the target line is the dimension A,
which according to the present invention, ranges from 4.063 in. to
4.47 in. The face wall height dimension G in FIG. 3, is 1.563 in.
to 1.720 in. The total face height shown also in FIG. 3 and
designated B, is 1.600 in. to 1.758 in. The rear clubhead height D,
also shown in FIG. 3, ranges according to the present invention
from 0.750 in. to 0.825 in. The height of the toe wall designated F
in FIG. 5, ranges from 1.500 in. to 1.650 in., according to the
present invention. The height of the toe wall 24 designated J,
ranges from 0.875 to 0.963.
Also as seen in FIG. 5, the dimension E, which is the perpendicular
distance from the axis of the hosel 17 to the furthest projection
of the heel of the clubhead, ranges according to the present
invention, from 0.563 in. to 0.625 in. The inside diameter of the
hosel 17 is 0.334 in.
As seen in FIG. 6, the lateral width H of the cavity 11 in the
bottom of the present clubhead, is 1.625 in.
As seen in FIGS. 5, 6 and 8, a ring or retainer 36 is formed
integrally with the forward face wall 14 and has an axis coincident
with the axis of the power shaft 12. The inside wall of the ring 36
is tapered rearwardly outwardly at a 3 degree angle. A second ring
or retainer 37, elliptical in configuration, is formed integrally
on the lower rear surface of the top wall 20 and also has an axis
coincident with the axis of the power shaft 12.
An important aspect of the present invention is that the power
shaft 12 is integral with the integral ring 36 at its forward end
and with the rear ring 37 at its rear end, which is essential to
achieving not only clubhead integrity but to achieve, the desired
increase in resonant frequency of the front face 12, as well as the
desired rebound characteristic of the front face. To achieve this
the shaft 12 may be cast with either the face wall or the rear
portion of the clubhead and then either press fitted or welded to
the other part. Or the shaft can be welded, in some cases, to
both.
As seen in FIG. 6, the heel wall 24 and the toe wall 29 have bottom
rails 40 and 41 formed therein that serve to set the clubhead up in
its proper orientation when lying on the ground. Rails 40 and 41
have pads 42 and 43 respectively at their forward ends that provide
the set-up for the adjacent clubhead front wall 14. It should be
understood that the volume of the present clubhead; i.e. on the
order of 250-300 cc. is the outside volume of the clubhead
including the volume of the open area 11. That is, the volume
definition assumes that the open area is enclosed as opposed to
being open as shown in the drawings. Furthermore in this regard, it
should be noted that the mounting and assembly of power shaft 12 is
adaptable to clubheads that have completely enclosed sole plates as
opposed to the partly open sole plate arrangement of the clubhead
10 illustrated in the present drawings.
An important aspect of the present invention and as shown more
clearly in the sub-assembly illustrated in FIG. 9, is that the
hosel 17 includes a first annular portion 46 formed in the top wall
20 and a second lower annular portion 47, which is formed
integrally with the heel weight wall 33. It should also be
understood that the lower annular portion 47 could also be formed
in the heel wall 24 or in the sole plate of clubs with fully formed
sole plates. The annular portions 46 and 47, since they are spaced
apart, at least 0.500 inches have significantly less weight than
present day hosel configurations. It should also be understood that
lower annular portion 47 has a through-bore 48 therethrough that
opens to the lower part of the club permitting the club shaft to be
extended completely therethrough during assembly.
During assembly, adhesive is applied to the club shaft and its tip
inserted in both bosses 46 and 47 projecting slightly downwardly
from the boss 47. The adhesive or bonding agent, usually epoxy, is
extended, prior to insertion, over a sufficient length of the tip
end of the shaft and the shaft is rotated as it is inserted into
the bosses so that epoxy covers the shaft between the upper boss 46
and the lower boss 47 and attaches to these bosses forming a sleeve
50 around the shaft attached to both of the bosses. In essence,
this defines a continuous hosel portion of rigid, hard epoxy
between the upper boss 46 and the lower boss 47 of significantly
reduced weight without sacrificing any structural integrity. The
wide spacing between the upper annular boss 46 and the lower
annular boss 47 provides less concentrated club shaft torquing than
the designer normally finds in the relatively short hosels found in
present day metal woods.
As seen in FIG. 8, a short forward wall 52 is formed integrally
with and extends rearwardly from the lower part of the club face 14
between rails 40 and 41, and it has an upwardly extending or
arcuate flange 53 that provides an "I" beam or "T" beam effect with
portion 52 to support the front club face.
As seen in FIGS. 12 and 13, one embodiment of the clubhead 10 can
be manufactured in two parts; namely; a forward part 55 and a rear
part 56. The forward part 55 includes front wall 14, top wall 20,
hosel 17, toe weight wall 32, and heel weight wall 33. The rear
portion 56 includes toe weight wall 29, connecting portion 31, heel
weight wall 24, bottom wall portion 52, and flange 53, castings or
forgings 55 and 56 are joined together by known welding techniques.
It should be understood, however, that the preferred casting and
assembly techniques for the present invention are illustrated in
FIGS. 19, 20 and 21, as will appear more clearly hereinafter.
As discussed above, the power shafts, according to one embodiment
of the present invention, shown as 12a, 12b, 12c and 12d, in FIGS.
14 to 18, match the rebound and a resonant frequency to the swing
speed of the golfer. The power shaft 12a illustrated in FIGS. 14
and 15, is designed for the high swing speed golfer, on the order
of 100 to 125 mph(ft/sec). The power shaft 12b, in FIG. 16, is
designed for the 85 to 100 mph swing speed golfer; the power shaft
12c in FIG. 17 is designed for the 70 to 85 mph swing speed golfer,
and the power shaft 12d in FIG. 18 is designed for the golfer
having a swing speed below 70 mph(below x ft/sec). The power shafts
12a to 12d are all of equal weight. In general, the club head
bodies 10 (without the power shaft 12) have a weight in the range
of 150 to 180 g., the power shafts 12 have a weight in the range of
10 to 60 g., and total head weight is in the range of about 190 to
210 g. In a 190 to 205 gms. high titanium alloy head, the power
shafts are all about 50 gms., or approximately 25% of the total
clubhead weight. In stainless, the power shafts are 20 gms. or
about 10% of total head weight. The power shafts 12a to 12d have
increasing inside diameters in through passages 60a, 60b, 60c and
60d so that the power shafts provide increasing higher rigidity,
increasingly higher modulus and increasingly faster rebound to the
front face as one moves from power shaft 12d to power shaft 12a. To
maintain the total overall weight of each of the power shafts the
same, and hence, the overall weight of the clubhead is
approximately the same, for all golfers, an annular threaded boss
61 is provided transverse to or radial to the passages 60 in each
of the power shafts into which a cylindrical weight 62a, 62b, 62c,
or 62e is threaded, each having progressively increasing axial
length and weights to compensate for the loss of weight caused by
the increasing diameter of the through passages 60a-60d. An
integral annular ring 67 is provided on the forward end of each of
the power shafts to seat neatly within the forward ring 36. Annular
portion 67 has a depth approximately equal to forward ring 36
providing a shoulder 68 that increasing the service area for
weldment location between the annular ring 67 and the annular ring
36. Ring 67 has a 3 degree inwardly forwardly tapered outer surface
so the shaft can be press fitted into ring 36 which has the same
taper on its inner surface. Press fitting can eliminate the need
for welding the shafts to the club head. A similar annular portion
could be provided at the rear end of the shafts 12a to facilitate
welding to rear ring 37 but are not shown in the drawings.
A preferred method of manufacturing the present invention is
illustrated in FIGS. 19, 20 and 21, and this method is particularly
directed to facilitating the insertion of the shaft 12 into the
clubhead assembly and to preloading the shaft 12 against the front
face 14.
The clubhead 10 is constructed according to FIGS. 19, 20 and 21, in
two pieces. The first being the forward piece 70 containing the
forward ring 36, and the rear piece 71 containing the rear ring 37.
The forward piece 70, which may be cast preferably by investment
casing and preferably utilizing the light-weight high surface
hardness alloys discussed above, includes the forward face 14, the
honeycomb face reinforcement 18, the integral ring 36, the heel
weight wall 37 with its annular hosel boss 47 integrally formed
therewith, and forward wall 32.
The rear clubhead portion 71 is an integral casting including top
wall 20, hosel upper boss 46, rear ring 37 integrally formed
underneath the rear portion of top wall 20, toe wall 29, heel wall
24, and a connecting wall portion.
After rough finishing the two castings 70 and 71, they are placed
in a jig including a forward component jig 75, and a rear component
jig 76 that firstly hold respectively the forward portion 70 of the
clubhead and the rear portion 71 of the clubhead, and at the same
time direct the two portions toward one another. Shaft 12 is
inserted into forward ring 36 and rear ring 37 prior to placement
into jig 75, 76. After placement into the jig, the jig moves the
forward portion 70 in the direction of rear portion 71. Thereafter,
a program welding system 80 welds the front portion 70 to the rear
portion 71 connecting the parts together.
* * * * *