U.S. patent application number 10/349161 was filed with the patent office on 2004-07-22 for low torque composite golf shaft.
Invention is credited to Brown, Donald, Haas, Neal.
Application Number | 20040142760 10/349161 |
Document ID | / |
Family ID | 32712678 |
Filed Date | 2004-07-22 |
United States Patent
Application |
20040142760 |
Kind Code |
A1 |
Haas, Neal ; et al. |
July 22, 2004 |
Low torque composite golf shaft
Abstract
A golf shaft is provided having a tip portion and a butt
portion. The shaft includes a first torsionally resistant flag
extending along the entire length of the shaft. The shaft also
includes a second torsionally resistant flag which only extends
over the tip portion of the shaft. In this way, the tip portion of
the shaft includes two torsionally resistant flags for providing
enhanced torsion resistance without negatively impacting the
bending stiffness or weight of the overall shaft.
Inventors: |
Haas, Neal; (San Diego,
CA) ; Brown, Donald; (San Diego, CA) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
32712678 |
Appl. No.: |
10/349161 |
Filed: |
January 22, 2003 |
Current U.S.
Class: |
473/319 |
Current CPC
Class: |
A63B 60/0081 20200801;
A63B 60/10 20151001; A63B 60/06 20151001; A63B 2209/02 20130101;
A63B 60/08 20151001; A63B 60/00 20151001; A63B 53/10 20130101 |
Class at
Publication: |
473/319 |
International
Class: |
A63B 053/10 |
Claims
What is claimed is:
1. A shaft comprising: a plurality of layers of material, each
layer of material including a plurality of fibers in a pre-selected
orientation, the plurality of layers including: a first layer of
material including at least two sets of fibers arranged at an angle
with respect to each other and extending along a first prescribed
length of the shaft; and a second layer of material including at
least two sets of fibers arranged at an angle with respect to each
other and extending along a second prescribed length of the shaft,
the second prescribed length of the shaft being shorter than the
first prescribed length and including a tip end of the shaft.
2. The shaft of claim 1 wherein each of said first and second
layers of material further comprises: a first set of parallel
fibers aligned at about a +45 degree angle relative to the
longitudinal axis of the shaft; and a second set of parallel fibers
aligned at about a -45 degree angle relative to the longitudinal
axis of the shaft.
3. The shaft of claim 1 wherein the plurality of layers of material
further includes: a third layer of material including a plurality
of parallel fibers aligned axially relative to a longitudinal axis
of the shaft.
4. The shaft of claim 3 wherein the plurality of layers of material
further includes: a fourth layer of material including a plurality
of parallel fibers aligned perpendicularly relative to the
longitudinal axis of the shaft.
5. The shaft of claim 4 wherein each of said first and second
layers of material further comprises: a first set of parallel
fibers aligned at about a +45 degree angle relative to the
longitudinal axis of the shaft; and a second set of parallel fibers
aligned at about a -45 degree angle relative to the longitudinal
axis of the shaft.
6. A shaft comprising: a plurality of layers of material, each
layer including a plurality of fibers in a pre-selected
orientation, the plurality of layers including: at least one bend
stiffening layer of material including a plurality of parallel
fibers aligned along a longitudinal axis of the shaft; at least one
crush resistant layer of material including a plurality of parallel
fibers aligned perpendicular to the longitudinal axis of the shaft;
and two torsion resistant layers of material, each torsion
resistant layer including a first set of parallel fibers aligned at
a first angle relative to the longitudinal axis of the shaft and a
second set of parallel fibers aligned at a second angle relative to
the longitudinal axis of the shaft and crossing the first set of
parallel fibers.
7. The shaft of claim 6 wherein one of the at least two torsion
resistant layers of material is located over a sub-portion of the
shaft, the sub-portion including a tip section of the shaft.
8. The shaft of claim 6 wherein: said first angle is about +45
degrees relative to the longitudinal axis of the shaft; and said
second angle is about -45 degrees relative to the longitudinal axis
of the shaft.
9. A shaft comprising: a composite material including a plurality
of fibers dispersed therein in pre-selected orientations, the
plurality of fibers including: a first layer of biased fibers
extending along a first prescribed length of the shaft; a second
layer of biased fibers extending along a second prescribed length
of the shaft, the second prescribed length of the shaft being
shorter than the first prescribed length and including a tip
section of the shaft.
10. The shaft of claim 9 wherein each of said first and second
layers of biased fibers further comprises: a first set of parallel
fibers aligned at about a +45 degree angle relative to a
longitudinal axis of the shaft; and a second set of parallel fibers
aligned at about a -45 degree angle relative to the longitudinal
axis of the shaft.
11. The shaft of claim 9 wherein said plurality of fibers further
includes: a first set of parallel fibers aligned axially relative
to a longitudinal axis of the shaft.
12. The shaft of claim 11 wherein the plurality of fibers further
includes: a second set of parallel fibers aligned perpendicularly
relative to the longitudinal axis of the shaft.
13. A method of making a shaft comprising: wrapping a plurality of
layers of material over a mandrel, each layer of material including
a plurality of fibers dispersed in an uncured plastic in a
preselected orientation; processing the uncured plastic to form a
unitized structure; and removing the mandrel; wherein the wrapping
step includes: wrapping a first layer of material along a first
prescribed length of the mandrel, the first layer of material
including at least two sets of fibers arranged at an angle with
respect to each other; and wrapping a second layer of material
along a second prescribed length of the mandrel, the second layer
of material including at least two sets of fibers arranged at an
angle with respect to each other, the second prescribed length of
the mandrel being shorter than the first prescribed length and
including a tip section of the mandrel.
14. The method of claim 13 wherein each of said first and second
layers of material further comprises: a first set of parallel
fibers aligned at about a +45 degree angle relative to the
longitudinal axis of the mandrel; and a second set of parallel
fibers aligned at about a -45 degree angle relative to the
longitudinal axis of the mandrel.
15. The method of claim 13 wherein the wrapping step further
includes: wrapping a third layer of material around the mandrel,
the third layer of material including a plurality of parallel
fibers aligned axially relative to a longitudinal axis of the
mandrel.
16. The shaft of claim 15 wherein the wrapping step further
includes: wrapping a fourth layer of material around the mandrel,
the fourth layer of material including a plurality of parallel
fibers aligned perpendicularly relative to the longitudinal axis of
the mandrel.
17. The shaft of claim 16 wherein said first and second layers of
material further comprises: a first set of parallel fibers aligned
at about a +45 degree angle relative to the longitudinal axis of
the mandrel; and a second set of parallel fibers aligned at about a
-45 degree angle relative to the longitudinal axis of the
mandrel.
18. A method of making a shaft comprising: wrapping at least one
bend stiffening flag of material around a mandrel, the at least one
bend stiffening flag of material including a plurality of parallel
fibers dispersed in an uncured plastic and aligned along a
longitudinal axis of the mandrel; wrapping at least one crush
resistant flag of material around the mandrel, the at least one
crush resistant flag of material including a plurality of parallel
fibers dispersed in an uncured plastic and aligned perpendicular to
the longitudinal axis of the mandrel; wrapping two torsion
resistant flags of material around the mandrel, each of the two
torsion resistant flags including a first set of parallel fibers
aligned at a first angle relative to the longitudinal axis of the
mandrel and a second set of parallel fibers aligned at a second
angle relative to the longitudinal axis of the mandrel and crossing
the first set of parallel fibers; processing the uncured plastic to
form a unitized structure; and removing the mandrel.
19. The method of claim 18 wherein said step of wrapping two
torsion resistant flags of material around the mandrel further
comprises wrapping one of said two torsion resistant flags around a
sub-portion of the mandrel, the sub-portion including a tip section
of the mandrel.
20. The method of claim 18 wherein: said first angle is about +45
degrees relative to the longitudinal axis of the mandrel; and said
second angle is about -45 degrees relative to the longitudinal axis
of the mandrel.
21. A method of making a shaft comprising: depositing a composite
material over a mandrel, the composite material including a
plurality of fibers dispersed in an uncured plastic in pre-selected
orientations; processing the uncured plastic to form a unitized
structure; and removing the mandrel; wherein said depositing step
includes: depositing a first layer of biased fibers along a first
prescribed length of the mandrel; and depositing a second layer of
biased fibers along a second prescribed length of the mandrel, the
second prescribed length of the mandrel being shorter than the
first prescribed length and including a tip section of the
mandrel.
22. The shaft of claim 21 wherein each of said first and second
layers of biased fibers further comprises: a first set of parallel
fibers aligned at about a +45 degree angle relative to a
longitudinal axis of the mandrel; and a second set of parallel
fibers aligned at about a -45 degree angle relative to the
longitudinal axis of the mandrel.
23. The method of claim 21 wherein said depositing step further
includes: depositing a first set of parallel fibers along the
mandrel, the first set of parallel fibers being aligned axially
relative to a longitudinal axis of the mandrel.
24. The method of claim 23 wherein said depositing step further
includes: depositing a second set of parallel fibers along the
mandrel, the second set of parallel fibers being aligned
perpendicularly relative to the longitudinal axis of the mandrel.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to golf shafts and more
particularly, to a golf shaft having a low torque performance
profile.
BACKGROUND OF THE INVENTION
[0002] A modern trend within the golf industry is to employ larger
and larger driver heads. The theory behind this trend is that a
large driver head provides a bigger sweet spot on the face within
which good momentum transfer will take place between the head and a
golf ball. This should translate into greater distance.
[0003] One drawback of large driver heads is that they are more
difficult to control than conventional sized driver heads. As such,
the user may gain greater distance but will sacrifice shot
accuracy. Much of the loss in shot accuracy is attributable to the
misalignment of the driver head with the ball at impact. The center
of gravity of a large driver head is offset from the longitudinal
axis of the shaft by a great distance. The inertia forces set up
during a down swing induce twisting in the shaft which affects the
alignment of the head relative to the ball at impact. This problem
is exacerbated if the ball makes contact towards the toe of the
head.
[0004] Club head misalignment can be influenced by controlling the
torsional stiffness of the shaft. The torsional stiffness of the
shaft resists the twisting of the club head during the swing and
particularly when there is less than centered contact between the
ball and head. Shafts having high torsional stiffness are available
in the marketplace and are generally know as low torque shafts.
[0005] One disadvantage of conventional low torque shafts is that a
sacrifice in bending stiffness and weight is made in order to
enhance torsional stiffness. That is, torsional resistance and
bending stiffness are both increased in conventional low torque
shafts. Bending stiffness provides the trajectory of the ball, the
feel of the club, and contributes to the distance resulting from
each hit. In general, shafts with a low bending stiffness are
desirable for most golf shots.
[0006] Recent studies have shown that only the tip section of the
shaft provides the torsional resistance necessary to prevent club
head twisting at impact. This is because contact between the club
head and ball is a very brief dynamic event and only the tip
section of the shaft gets loaded during this time period. The event
is effectively over before the full length of the shaft is
loaded.
[0007] In view of the foregoing, it would be desirable to provide a
composite shaft that incorporates the benefits of a torsionally
stiff tip section without increasing the bending stiffness in the
tip area as usually associated with low torque graphite shafts. By
not increasing the bending stiffness of the tip, a lower bend point
is provided for the shaft which maintains good overall feel. The
lower bend point will also promote a desirable high ball
trajectory.
SUMMARY OF THE INVENTION
[0008] A golf shaft is provided having a tip portion and a butt
portion. A first torsionally resistant flag extends along the
entire length of the shaft. A second torsionally resistant flag
only extends over the tip portion of the shaft. In this way, the
tip portion includes two torsionally resistant flags for providing
enhanced torsion resistance without negatively impacting the
binding stiffness or weight of the overall shaft.
[0009] In one embodiment, a plurality of bend stiffening flags are
provided along the length of the shaft. These flags include a
plurality of parallel fibers aligned axially relative to a
longitudinal axis of the shaft. A plurality of crush resistant
flags are also provided along the length of the shaft. These flags
include a plurality of parallel fibers aligned perpendicularly
relative to the longitudinal axis of the shaft. A first torsion
resistant flag is provided along the length of the shaft and a
second torsion resistant flag is provided along the tip portion of
the shaft. The torsion resistant flags include a plurality of
fibers arranged in a matrix extending at .+-.45 degrees relative to
the longitudinal axis of the shaft.
[0010] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0012] FIG. 1 is a side view showing a golf club shaft with a grip
and head shown in phantom;
[0013] FIG. 2 is a view of a first flag of composite material
having a first plurality of parallel non-metallic fibers extending
angularly from one side of the flag to another side and woven with
a second plurality of parallel non-metallic fibers which also
extend from the one side to the other side of the flag all carried
in an uncured plastic material;
[0014] FIG. 3 is a view of a second flag of composite material
having a first plurality of parallel non-metallic fibers extending
angularly from one side of the flag to an opposite side and woven
with a second plurality of parallel non-metallic fibers which also
extend from the one side to the other side of the flag all carried
in an uncured plastic material;
[0015] FIG. 4 is a view of a third flag of composite material
having a plurality of parallel non-metallic fibers extending from
one end to an opposite end of the flag carried in an uncured
plastic material;
[0016] FIG. 5 is a view of a fourth flag of composite material
having a plurality of parallel non-metallic fibers extending from
one end to an opposite end of the flag carried in an uncured
plastic material;
[0017] FIG. 6 is a view of a fifth flag of composite material
having a plurality of parallel non-metallic fibers extending from
one end to an opposite end of the flag carried in an uncured
plastic material;
[0018] FIG. 7 is a view of a sixth flag of composite material
having a plurality of parallel non-metallic fibers extending from
one end to an opposite end of the flag carried in an uncured
plastic material;
[0019] FIG. 8 is a view of a seventh flag of composite material
having a plurality of parallel non-metallic fibers extending from
one side to an opposite side of the flag carried in an uncured
plastic material;
[0020] FIG. 9 is a view of a eighth flag of composite material
having a plurality of parallel non-metallic fibers extending from
one side to an opposite side of the flag carried in an uncured
plastic material;
[0021] FIG. 10 is a view of a ninth flag of composite material
having a plurality of parallel non-metallic fibers extending from
one side to an opposite side of the flag carried in an uncured
plastic material;
[0022] FIG. 11 is a side view of a steel mandrel;
[0023] FIG. 12 is a graph showing the various diameters provided
along the length of the mandrel shown in FIG. 11;
[0024] FIG. 13 is a partial sectional view showing the flags of
FIGS. 2-10 wrapped on the mandrel of FIG. 11;
[0025] FIG. 14 is a partial sectional view showing the assembly of
FIG. 13 after heat processing;
[0026] FIG. 15 is a graph showing the various wall thicknesses
provided along the length of the shaft of FIG. 14;
[0027] FIG. 16 is a graph showing the various outside diameters
provided along the length of the shaft of FIG. 14;
[0028] FIG. 17 is a graph showing the torsional resistance of the
shaft of the present invention as compared to a conventional low
torque shaft and a low modulus shaft of the prior art; and
[0029] FIG. 18 is a graph showing the bending stiffness of the
shaft of the present invention as compared to a conventional low
torque shaft and a low modulus shaft of the prior art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] The following description of the preferred embodiments is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses.
[0031] Referring to FIG. 1, a golf club 10 is illustrated including
a shaft 12, a club head 14 shown in phantom, and a grip 16, also
shown in phantom. The shaft 12, which is generally tubular with an
central axial opening, includes a butt end 18 to which the grip 16
is attached and a tip end 20 to which the head 14 is secured. An
intermediate section 22 of the shaft 12 extends between the butt
end 18 and the tip end 20 thereof and tapers therebetween.
[0032] As shown in FIGS. 2-10, the shaft 12 is preferably formed by
a plurality of flags or sheets including a first flag 24, a second
flag 26, a third flag 28, a fourth flag 30, a fifth flag 32, a
sixth flag 34, a seventh flag 36, an eighth flag 38, and a ninth
flag 40, each of which is composed of a composite material
including graphite fibers and an epoxy resin matrix which carries
the fibers therein. The flags are typically cut to the desired
dimensions from a larger rolls of materials.
[0033] As shown in FIG. 2, the first flag 24 includes a wide first
end 42 and a narrow second end 44 axially spaced apart from the
wide end 42 along an axis 46. Side 48 extends parallel to the axis
46 from the wide end 42 to the narrow end 44. Side 50 angles
relative to the axis 46 from the wide end 42 to the narrow end 44.
The flag 24 includes a first set of parallel graphite fibers 52
carried by an epoxy resin matrix 54 which extend at an angle with
respect to the axis 46 from the side 48 to the side 50. A second
set of parallel graphite fibers 56 carried by the epoxy matrix 54
extend at an angle relative to the axis 46 in a direction opposite
the angular extension of the first set of fibers 52 such that the
fibers 52 and 56 cross each other to form a biased ply. The off
axis fibers 52 and 56 are also known in the art as cross plies and
radials. Such off axis fibers provide a combination of torsional
resistance and bending stiffness.
[0034] In one embodiment, the flag 24 is formed from two
overlapping pieces of material 24a and 24b that are adhered to
one-another to form the unitary flag 24. The overlap of the
material pieces 24a and 24b is preferably offset by an amount
approximately equal to a quarter wrap of the circumference of the
mandrel (described below) corresponding to that portion of the flag
24. This promotes adhesion of the flag 24 to the mandrel. It should
also be appreciated that the material piece 24a carries the first
set of parallel fibers 52 while the second material piece 24b
carries the second set of parallel fibers 56. When the two pieces
of material 24a and 24b are adhered to one another to form the
unitary flag 24, the fibers 52 and 56 cross the longitudinal axis
46 at opposite angles so as to cross one another and form the
biased ply.
[0035] Preferably, the off-axis fibers 52 cross the axis 46 at an
angle between thirty and sixty degrees and most preferably at an
angle of forty-five degrees. The off-axis fibers 56 preferably
cross the axis 46 at an angle between minus thirty and sixty
degrees and most preferably at an angle of minus forty-five
degrees. At .+-.45 degrees, the fibers 52 cross the fibers 56 at an
angle of ninety degrees. While other crossing angles could
theoretically be used, a .+-.45 degree orientation provides maximum
torsional resistance and medium bending stiffness. That is,
torsional stiffness increases along a bell curve from a minimum at
a fiber alignment of 0 degrees relative to the longitudinal axis of
the shaft to a maximum at a fiber alignment of 45 degrees relative
to the longitudinal axis. The torsional stiffness decreases along
the bell curve from the maximum at a fiber alignment of 45 degrees
to a minimum at a fiber alignment of 90 degrees (relative to the
longitudinal axis).
[0036] In contrast, bending stiffness linearly decreases from a
maximum at a fiber alignment relative to the longitudinal axis of 0
degrees to a minimum at a fiber alignment relative to the
longitudinal axis of 90 degrees. A fiber alignment of 45 degrees
provides half the bending stiffness of fibers aligned at 0 degrees
and twice the bending stiffness of fibers aligned at 90 degrees.
For the purpose of this disclosure, flags including off-axis fibers
are referred to as torsion resistant flags, flags including fibers
aligned at 0 degrees are referred to as bend stiffening flags, and
flags including fibers aligned at 90 degrees are referred to as
crush resistant flags.
[0037] Further, as described above, the fibers 52 are preferably
overlapped with the fibers 56. Alternatively, the fibers 52 and 56
could be woven in an interleaved fashion rather than being
overlapped without departing from the spirit and scope of the
invention. In a preferred embodiment of the present invention, when
it is desirable to provide a shaft 12 (FIG. 1) having an overall
length of 46 inches, the torsion resistant flag 24 includes a 15
inch long side 48, a 2.5 inch long first end 42, and a 0.35 inch
long second end 44.
[0038] Referring to FIG. 3, the second flag 26 includes a first end
58 and a parallel second end 60 axially spaced apart from the first
end 58 along an axis 62. Sides 64 and 66 extend parallel to one
another and the axis 62 between the first end 58 and the second end
60. As with the first flag 24, the second flag 26 includes a first
set of graphite fibers 67 carried by an epoxy resin matrix 68 which
extend at an angle with respect to the axis 62 from the side 64 to
the side 66. A second set of graphite fibers 70 carried by the
epoxy matrix 68 extend at an angle relative to the axis 62 in a
direction opposite the angular extension of the first set of fibers
67 such that the fibers 67 and 70 cross each other to form a biased
ply.
[0039] Also as with the first flag 24, the second flag 26 is formed
from two overlapping pieces of material 26a and 26b that are
adhered to one-another to form the unitary flag 26. The overlap of
the material pieces 26a and 26b is preferably offset by an amount
approximately equal to a quarter wrap of the circumference of the
mandrel (described below) corresponding to that portion of the flag
26. The material piece 26a carries the first set of fibers 67 while
the second material piece 26b carries the second set of fibers 70.
When the two pieces of material 26a and 26b are adhered to one
another to form the unitary flag 26, the fibers 67 and 70 cross the
longitudinal axis 62 at opposite angles so as to cross one another
and form the biased ply.
[0040] In one embodiment, the off-axis fibers 67 cross the axis 62
at an angle of forty-five degrees while the off-axis fibers 70
cross the axis 62 at an angle of minus forty-five degrees such that
the fibers 67 cross the fibers 70 at an angle of ninety degrees.
Other angles such as described with reference to the first flag 24
may also be used. Also, an overlapping construction of the fibers
67 and 70 is preferred although a woven construction could also be
used. When it is desirable to provide a shaft 12 (FIG. 1) having an
overall length of 46 inches, the torsion resistant flag 26 includes
47 inch long sides 64 and 66 and 2.7 inch long ends 58 and 60.
[0041] Referring to FIG. 4, the third flag 28 includes a wide first
end 72 and a tip or vertex 74 axially spaced apart from the wide
end 72 along an axis 76. Side 78 extends parallel to the axis 76
from the wide end 72 to the vertex 74. Side 80 angles relative to
the axis 76 from the wide end 72 to the vertex 74. The flag 28
includes a plurality of spaced parallel graphite fibers 82 carried
by an epoxy resin matrix 84 which extend parallel with respect to
the axis 76 from the wide end 72 to the vertex 74. Fibers formed in
this 0 degree direction provide maximum bending stiffness for the
shaft 12 (FIG. 1). For a 46 inch shaft 12 (FIG. 1), the bend
stiffening flag 28 includes a 15 inch long side 78 and a 2 inch
long end 72.
[0042] Referring to FIG. 5, the fourth flag 30 includes a narrow
first end 86 and a wide second end 88 axially spaced apart from the
narrow end 86 along an axis 90. Side 92 extends parallel to the
axis 90 from the narrow end 86 to the wide end 88. Side 94 angles
relative to the axis 90 from the narrow end 86 to the wide end 88.
The direction of the angle of the side 94 is opposite to that of
the first and third flags 24 and 28. The flag 30 includes a
plurality of spaced parallel graphite fibers 96 carried by an epoxy
resin matrix 98 which extend parallel with respect to the axis 90
from the narrow end 86 to the wide end 88. For a 46 inch shaft 12
(FIG. 1), the bend stiffening flag 30 includes a 47 inch long side
92, a 2.3 inch long narrow end 86, and a 4.4 inch long wide end 88.
The flag 30 is then trimmed along the dot and dash line 99 shown in
FIG. 5 from the wide end 88 such that the wide end 88 is 3.7 inches
long and the side 94 includes a first portion 100 parallel to the
axis 90 and a second portion 102 angled relative to the axis 90.
This ensures rotational consistency and ply-balancing when the flag
is ultimately wrapped around a mandrel (described below).
[0043] Referring to FIG. 6, the fifth flag 32 includes a narrow
first end 104 and a wide second end 106 axially spaced apart from
the narrow end 104 along an axis 108. Side 110 extends parallel to
the axis 108 from the narrow end 104 to the wide end 106. Side 112
angles relative to the axis 108 from the narrow end 104 to the wide
end 106. The side 112 angles in the same direction as the side 94
of the fourth flag 30 (FIG. 5.) The flag 32 includes a plurality of
spaced parallel graphite fibers 114 carried by an epoxy resin
matrix 116 which extend parallel with respect to the axis 108 from
the narrow end 104 to the wide end 106. For a 46 inch shaft 12
(FIG. 1), the bend stiffening flag 32 includes a 47 inch long side
110, a 1.2 inch long narrow end 104, and a 2.3 inch long wide end
106. The flag 32 is then trimmed along the dot and dash line 117
shown in FIG. 6 from the wide end 106 such that the wide end 106 is
1.9 inches long and the side 112 includes a first portion 118
parallel to the axis 108 and a second portion 120 angled relative
to the axis 108.
[0044] Referring to FIG. 7, the sixth flag 34 includes a wide first
end 122 and a tip or vertex 124 axially spaced apart from the wide
end 122 along an axis 126. Side 128 extends parallel to the axis
126 from the wide end 122 to the vertex 124. Side 130 angles
relative to the axis 126 from the wide end 122 to the vertex 124.
The flag 34 includes a plurality of spaced parallel graphite fibers
132 carried by an epoxy resin matrix 134 which extend parallel with
respect to the axis 126 from the wide end 122 to the vertex 124.
For a 46 inch shaft 12 (FIG. 1), the bend stiffening flag 34
includes an 8 inch long side 128 and a 2 inch long end 122.
[0045] Referring to FIG. 8, the seventh flag 36 includes a narrow
first end 136 and a wide second end 138 axially spaced apart from
the narrow end 136 along an axis 140. Side 142 extends parallel to
the axis 140 from the narrow end 136 to the wide end 138. Side 144
angles relative to the axis 140 from the narrow end 136 to the wide
end 138. The side 144 angles in the same direction as the sides 94
and 112 of the fourth and fifth flags 30 and 32 (FIGS. 5 and 6.)
The flag 36 includes a plurality of spaced parallel graphite fibers
146 carried by an epoxy resin matrix 148 which extend perpendicular
with respect to the axis 140 from the side 142 to the side 144.
Fibers oriented in this 90 degree direction provide maximum hoop
strength or crushing resistance in the resulting shaft. For a 46
inch shaft 12 (FIG. 1), the crush resistant flag 36 includes a 47
inch long side 142, a 2.3 inch long narrow end 136, and a 4.4 inch
long wide end 138.
[0046] Referring to FIG. 9, the eighth flag 38 includes first and
second ends 150 and 152 axially spaced apart along an axis 154.
Unlike the second end 152 which is perpendicular to the axis 154,
the first end 150 angles relative to the axis 154 to provide a more
abrupt taper in the form of a step in the final sidewall of the
shaft 12 (FIG. 12). Sides 156 and 158 are spaced apart from one
another and extend parallel to the axis 154 from the first end 150
to the second end 152. The flag 38 includes a plurality of spaced
parallel graphite fibers 160 carried by an epoxy resin matrix 162
which extend perpendicular with respect to the axis 154 from the
side 156 to the side 158. For a 46 inch shaft 12 (FIG. 1), the
crush resistant flag 38 includes a 24 inch long side 156, a 23 inch
long side 158, and a 3.8 inch long second end 150.
[0047] Referring to FIG. 10, the ninth flag 40 includes a first end
164 and a parallel second end 166 axially spaced apart from the
first end 164 along an axis 168. Sides 170 and 172 are spaced apart
from one another and extend parallel to the axis 168 between the
first end 164 and the second end 166. The flag 40 includes a
plurality of spaced parallel graphite fibers 174 carried by an
epoxy resin matrix 176 which extend perpendicular with respect to
the axis 168 from the side 170 to the side 172. For a 46 inch shaft
12 (FIG. 1), the crush resistant flag 40 includes 0.25 inch long
sides 170 and 172 and 3 inch long ends 164 and 166. The ninth flag
40 forms what is known in the art as a dog-knot which is used for
pulling the shaft during the manufacturing process. This dog-knot
is usually cut off to form the final shaft.
[0048] In one embodiment of the present invention, the composite
material of the first--ninth flags include graphite fibers and an
epoxy resin matrix. However, the fibers could be formed from
fiberglass, aramid, boron or other suitable fiber materials, and
the epoxy resin matrix could be polyester, vinylester, nylon, or
any other suitable thermoset or thermoplastic matrix, all without
departing from the spirit and scope of the invention.
[0049] It is noted that the number of fibers shown in FIGS. 2-10 is
limited for illustration purposes only to show the alignment and
orientation of the much larger number of fibers actually contained
in each flag. As noted above, the orientation of the fibers
controls the functional or style of the flag. That is, the biased
or off-axis fibers (cross-plies) in FIGS. 2 and 3 provide torsion
resistant flags 24 and 26. The parallel fibers aligned axially
relative to the longitudinal axes in FIGS. 4-7 provide bend
stiffening flags 28, 30, 32 and 34. The parallel fibers aligned
perpendicularly relative to the longitudinal axes in FIGS. 8-10
provide the crush resistant flags 36, 38 and 40.
[0050] Referring to FIGS. 11 and 12, a rigid mandrel 178 having a
rod-like shape and is formed from any suitable material such as,
for example, steel. The mandrel 178 is formed with a small end
section 180 and a large end section 182 opposite the small end
section 180 along an axis 184. The mandrel 178 also includes first
divergent section 186 extending from the small end 180 to a second
divergent section 188. The second divergent section 188 extends to
a third divergent section 190 which extends to a fourth divergent
section 192. The fourth divergent section 192 extends to a fifth
divergent section 194 which terminates at the large end 182. The
mandrel illustrated in FIG. 11 includes exaggerated divergences for
ease of viewing.
[0051] For a 46 inch shaft 12 (FIG. 1), the first divergent section
186 preferably has a length of 10 inches with a diameter at the
small end 180 of 0.135 inch and a diameter at an opposite end of
0.217 inch. The second divergent section 188 preferably has a
length of 8.7 inches, a diameter at the end of the first divergent
section 186 of 0.217 inch and a diameter at an opposite end of 0.41
inch. The third divergent section 190 preferably has a length of
14.5 inches, a diameter at the end of the second divergent section
188 of 0.41 inch and a diameter at an opposite end of 0.531 inch.
The fourth divergent section 192 preferably has a length of 8.8
inches, a diameter at the end of the third divergent section 190 of
0.531 inch and a diameter at an opposite end of 0.537 inch. The
fifth divergent section 194 preferably has a length of 14 inches, a
diameter at the end of the fourth divergent section 192 of 0.537
inch and a diameter at the large end 182 of 0.54 inch.
[0052] Referring to FIG. 13, in the manufacture of the shaft 12
(FIG. 1), the first--ninth flags are consecutively wrapped over the
mandrel 178. In this illustration, the diameter to length ratio of
the mandrel 178 is grossly exaggerated to enable the various flags
wrapped thereabout to be more easily recognized. During
manufacture, the first flag 24 is initially wrapped over a first
axial end of the mandrel 178 known as the tip section. The angled
side 50 shown in FIG. 2 causes to flag 24 to taper along the length
of the mandrel 178. The angled sides or ends of other flags provide
the same result.
[0053] Next, the second flag 26 is wrapped over the first flag 24
and the remainder of the mandrel 178. Thereafter, the third flag 28
is wrapped over the second flag 26 adjacent the tip end of the
mandrel 178. Next, the fourth flag 30 is wrapped over the third
flag 28 and second flag 26 along the length of the mandrel 178.
Thereafter and in consecutive steps: the fifth flag 32 is wrapped
over the fourth flag 30; the sixth flag 34 is wrapped over the
fifth flag 32 adjacent the tip end of the mandrel 178; the seventh
flag 36 is wrapped over the sixth flag 34 and the fifth flag 32
along the length of the mandrel 178; and the eighth flag 38 is
wrapped over the seventh flag 36 proximate the butt end of the
mandrel 178. Finally, the ninth flag 40 is wrapped over the eighth
flag 38 adjacent the butt end of the shaft.
[0054] Advantageously, the torsional characteristics of the shaft
12 are not only dictated by the torsion resistant second flag 26,
but also by the torsion resistant first flag 24. In this regard,
since the first flag 24 is only wrapped around the mandrel 178 in a
location that will eventually form the tip section of the shaft,
the first flag 24 only effects the torsional characteristics of the
tip end of the shaft. As such, the torsional resistance of the
shaft 12 is specifically tailored within the tip section, where it
is needed the most, to provide the desired effect during the
down-swing and at club head/ball impact. Moreover, the first flag
24 does not negatively impact the bending stiffness of the shaft
but rather improves the bending stiffness of the shaft,
particularly in the tip section.
[0055] Upon the completion of the assembly of the flags on the
mandrel 178 as described above, a heat shrinkable film (not shown)
is wrapped around the sub-assembly 196 so that all portions of the
flags are confined between the mandrel 178 and the heat-shrinkable
film. The film-wrapped sub-assembly 196 is then processed through a
heated environment where the epoxy resin matrices of the flags
liquefy and generally blend together as a homogeneous mass. During
this process, the film shrinks to generally define the exterior
shape of the shaft. The film-wrapped sub-assembly 196 is then
removed from the heated environment and is cooled to cure the
homogenized epoxy resin. The result is the cured mass of plastic
material 198 shown in FIG. 14 defined by the mandrel 178 and film.
The film and mandrel are then removed to reveal the shaft 12 (FIG.
1) generally in the configuration shown in FIG. 14. A size-grinding
process and a surface finishing process may then be performed to
provide the shaft with the desired shape, parameters, and surface
finish. The preferred wall thicknesses of the shaft are shown in
FIG. 15 and the preferred outside diameters of the shaft are shown
in FIG. 16.
[0056] As compared to shafts of the prior art, the shaft of the
present invention provides enhanced torsional resistance at the
tip. Advantageously, the shaft of the present invention does this
without degrading the bending stiffness of the shaft. For example,
FIG. 17 shows a torsional resistance comparison of the shaft of the
present invention (line 200) with a conventional low torque shaft
(line 202) and a standard modulus shaft (line 204). As can be seen,
the new shaft provides about a 40% increase in torsional resistance
at the tip end of the shaft as compared with prior art low torque
shafts. Moreover, as shown in FIG. 18 where the bending stiffness
of the new shaft (line 206) is compared with a conventional low
torque shaft (line 208) and a standard modulus shaft (line 210),
the new shaft increases torsional resistance in the tip without
sacrificing bending stiffness. In fact, the new shaft provides a
20% improvement in bending stiffness at the tip end of the shaft as
compared to prior art low torque shafts.
[0057] It can be appreciated from the forgoing that the shaft of
the present invention has characteristics which make it very
suitable for today's new generation of oversized driver heads. The
high torsional stiffness of the tip promotes correct alignment of
the head through impact to maximize shot accuracy. Maintaining a
low bending stiffness in the tip provides a smooth, solid feel and
a desirable ball trajectory. Advantageously, these characteristics
are achieved at an ultralight weight which helps the golfer swing
the club faster to achieve more distance.
[0058] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *