U.S. patent application number 13/181117 was filed with the patent office on 2013-01-17 for golf club shaft assemblies with partially bonded and unbonded permanent inserts.
The applicant listed for this patent is Michael H.L. Cheng. Invention is credited to Michael H.L. Cheng.
Application Number | 20130017902 13/181117 |
Document ID | / |
Family ID | 47519221 |
Filed Date | 2013-01-17 |
United States Patent
Application |
20130017902 |
Kind Code |
A1 |
Cheng; Michael H.L. |
January 17, 2013 |
Golf Club Shaft Assemblies With Partially Bonded and Unbonded
Permanent Inserts
Abstract
A golf club shaft assembly including a golf club shaft and a
permanent shaft insert that is partially bonded, or is unbounded,
to the golf club shaft.
Inventors: |
Cheng; Michael H.L.; (Simi
Valley, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cheng; Michael H.L. |
Simi Valley |
CA |
US |
|
|
Family ID: |
47519221 |
Appl. No.: |
13/181117 |
Filed: |
July 12, 2011 |
Current U.S.
Class: |
473/319 ;
473/316; 473/318 |
Current CPC
Class: |
A63B 60/26 20151001;
A63B 53/10 20130101; A63B 60/00 20151001; A63B 53/08 20130101 |
Class at
Publication: |
473/319 ;
473/316; 473/318 |
International
Class: |
A63B 53/10 20060101
A63B053/10 |
Claims
1. A golf club shaft assembly, comprising: a golf club shaft having
an inner surface; and a shaft insert defining a tip end, a butt end
and a length that extends from the tip end to the butt end, and
having an outer surface that abuts the inner surface of the golf
club shaft; wherein the shaft insert is permanently secured within
the golf club shaft; and wherein the shaft insert is either not
bonded to the golf club shaft or is bonded to the golf club shaft
over less than the entire the length of the shaft insert.
2. A golf club shaft assembly as claimed in claim 1, wherein the
shaft insert comprises a hollow, tubular shaft insert.
3. A golf club shaft assembly as claimed in claim 2, wherein the
shaft insert comprises a thin wall and there no structures located
inwardly of the thin wall.
4. A golf club shaft assembly as claimed in claim 1, wherein the
shaft insert comprises a graphite shaft insert.
5. A golf club shaft assembly as claimed in claim 1, wherein the
shaft insert comprises a tapered shaft insert.
6. A golf club shaft assembly as claimed in claim 1, wherein the
shaft insert is not bonded to the golf club shaft over at least 90%
of the length of the shaft insert, the length being continuous and
beginning at the tip end of the insert.
7. A golf club shaft assembly as claimed in claim 1, wherein the
outer surface of the shaft insert is permanently bonded to the
inner surface of the golf club shaft over no more than 50% of the
length of the shaft insert.
8. A golf club shaft assembly as claimed in claim 7, wherein outer
surface of the shaft insert is permanently bonded to the inner
surface of the golf club shaft over no more than 10% of the length
of the shaft insert.
9. A golf club shaft assembly as claimed in claim 7, wherein outer
surface of the shaft insert is not permanently bonded to the inner
surface of the golf club shaft at the tip end of the shaft
insert.
10. A golf club shaft assembly as claimed in claim 7, wherein the
outer surface of the shaft insert is permanently bonded to the
inner surface of the golf club shaft with adhesive.
11. A golf club shaft assembly as claimed in claim 7, wherein the
outer surface of the shaft insert is permanently bonded to the
inner surface of the golf club shaft with a weld.
12. A golf club shaft assembly as claimed in claim 7, wherein outer
surface of the shaft insert is permanently bonded to the inner
surface of the golf club shaft with a bond that extends from a
location substantially adjacent to the butt end of the shaft insert
towards the tip end of the shaft insert.
13. A golf club shaft assembly as claimed in claim 1, further
comprising: a plug that abuts the shaft insert butt end and is
permanently bonded to the inner surface of the golf club shaft.
14. A golf club shaft assembly as claimed in claim 13, wherein the
outer surface of the shaft insert is not bonded to the inner
surface of the golf club shaft.
15. A golf club shaft assembly as claimed in claim 1, wherein the
golf club shaft comprises a fiber reinforced shaft.
16. A golf club shaft assembly as claimed in claim 1, wherein the
tip end and/or the butt end of the shaft insert is longitudinally
and/or rotationally movable relative to the adjacent portion of the
golf club shaft inner surface.
17. A golf club shaft assembly as claimed in claim 1, wherein the
tip end and/or the butt end of the shaft insert is in direct
contact with the golf club shaft inner surface.
18. A golf club shaft assembly, comprising: a golf club shaft
having an inner surface; and a hollow, tubular shaft insert,
defining a tip end and a butt end, permanently secured within the
golf club shaft such that the tip end and/or the butt end of the
shaft insert is longitudinally and/or rotationally movable relative
to the adjacent portion of the golf club shaft inner surface.
19. A golf club shaft assembly as claimed in claim 18, wherein the
shaft insert comprises a graphite shaft insert.
20. A golf club shaft assembly as claimed in claim 18, wherein the
shaft insert comprises a tapered shaft insert.
21. A golf club shaft assembly as claimed in claim 18, wherein only
one of the tip end and the butt end of the shaft inert is
longitudinally and/or rotationally movable relative to the adjacent
portion of the golf club shaft inner surface.
22. A golf club shaft assembly as claimed in claim 18, wherein the
shaft insert is permanently bonded to the golf club shaft at the
tip end of the insert or at the butt end of the insert; and the
shaft insert is not bonded to the golf club shaft over at least 90%
of the length of the shaft insert.
23. A golf club shaft assembly as claimed in claim 22, wherein the
shaft inert is permanently bonded to the golf club shaft with
adhesive.
24. A golf club shaft assembly as claimed in claim 18, wherein the
tip end and/or the butt end of the shaft insert is in direct
contact with the golf club shaft inner surface.
25. A golf club shaft assembly as claimed in claim 18, further
comprising: a plug that abuts the shaft insert butt end and is
permanently bonded to the inner surface of the golf club shaft.
26. A golf club shaft assembly as claimed in claim 25, wherein the
outer surface of the shaft insert is not bonded to the inner
surface of the golf club shaft.
27. A golf club shaft assembly as claimed in claim 18, wherein the
golf club shaft comprises a fiber reinforced shaft.
Description
BACKGROUND OF THE INVENTIONS
[0001] 1. Field of the Inventions
[0002] The present inventions relate generally to golf clubs.
[0003] 2. Description of the Related Art
[0004] Fiber reinforced resin shafts are commonly used in golf club
drivers and irons. Such shafts, which are typically hollow and
consist of a shaft wall formed around a tapered mandrel, may be
produced with varying stiffness and bending profiles. As a result,
golfers are able to choose shafts that are appropriate for their
particular swing. If a shaft is too stiff for the golfer, then the
shaft will not deflect sufficiently to generate a "kick" behind the
golf ball. Conversely, if the shaft is not stiff enough, then the
shaft will either lead or lag excessively, thereby causing the ball
to leave the club head at a launch angle that is higher or lower
than intended.
[0005] Another issue involves the stability of the shaft region
that is near the club head. Upon impacting the golf ball, this
region vibrates violently as does, to a lesser extent, other
portions of the shaft. Some shafts may even bend into an S-shape at
the center-of-percussion. One proposed method of stabilizing golf
club shafts involves adding additional layers of material to the
shaft in the tip section during the shaft manufacturing process in
an attempt to reduce or eliminate impact vibrations and
deformation.
[0006] The present inventor has determined that conventional
methods of increasing shaft stability are susceptible to
improvement. For example, additional layers of material do not
substantially decrease the impact vibrations and shaft deformation.
The additional layers of material do, on the other hand,
substantially increase longitudinal and torsional stiffness of the
shaft. The increased longitudinal and torsional stiffness alters
the playing characteristics of the shaft, and can render the shaft
too unforgiving for many golfers. The present inventor has also
determined that one reason for both of these shortcomings relates
to the fact that additional layers of material become an integral
part of the associated shaft over their entire length.
SUMMARY
[0007] A golf club shaft assembly in accordance with one embodiment
of a present invention includes a golf club shaft and a shaft
insert. The shaft insert is permanently secured within the golf
club shaft, and the shaft insert is either not bonded to the golf
club shaft or is bonded to the golf club shaft over less than the
entire length of shaft insert.
[0008] A golf club shaft assembly in accordance with one embodiment
of a present invention includes a golf club shaft and a shaft
insert. The shaft insert is permanently secured within the golf
club shaft such that the tip end and/or the butt end of the shaft
insert is longitudinally and/or rotationally movable relative to
the adjacent portion of the golf club shaft inner surface.
[0009] There are a variety of advantages associated with such golf
club shaft assemblies. For example, the insert will, over its
entire length, contribute to the reduction of impact vibrations and
deformation, but will do so without substantially increasing the
longitudinal and/or torsional stiffness of the shaft because the
shaft can move relative to a substantial portion (or all) of the
insert as the shaft bends and twists.
[0010] The above described and many other features of the present
inventions will become apparent as the inventions become better
understood by reference to the following detailed description when
considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Detailed description of embodiments of the inventions will
be made with reference to the accompanying drawings.
[0012] FIG. 1 is a side view of a golf club in accordance with one
embodiment of a present invention.
[0013] FIG. 2 is a cutaway view of a portion of the golf club
illustrated in FIG. 1.
[0014] FIG. 3A is section view taken along line 3A-3A in FIG.
2.
[0015] FIG. 3B is section view taken along line 3B-3B in FIG.
2.
[0016] FIG. 3C is section view taken along line 3C-3C in FIG.
2.
[0017] FIG. 4 is a partial section view of a portion of the golf
club shaft assembly illustrated in FIG. 2.
[0018] FIG. 5 is a partial section view of a portion of a golf club
shaft assembly in accordance with one embodiment of a present
invention.
[0019] FIG. 6 is a partial section view of a portion of a golf club
shaft assembly in accordance with one embodiment of a present
invention.
[0020] FIG. 7 is a partial section view of a portion of a golf club
shaft assembly in accordance with one embodiment of a present
invention.
[0021] FIG. 8 is a partial section view of a portion of a golf club
shaft assembly in accordance with one embodiment of a present
invention.
[0022] FIG. 9 is a partial section view showing a step in an
exemplary process for manufacturing the golf club shaft assembly
illustrated in FIGS. 1-4.
[0023] FIG. 10 is a partial section view showing a step in another
process for manufacturing a golf club shaft assembly.
[0024] FIG. 11 is a partial section view of a portion of a golf
club shaft assembly in accordance with one embodiment of a present
invention.
[0025] FIG. 12 is a section view of a portion of the golf club
shaft assembly illustrated in FIG. 11.
[0026] FIG. 13 is a side view of a plug coated with adhesive in
accordance with one embodiment of a present invention.
[0027] FIG. 14 is a side view of the plug illustrated in FIG. 13
with a portion not coated with adhesive.
[0028] FIG. 15 is a partial section view of a portion of a golf
club shaft assembly in accordance with one embodiment of a present
invention.
[0029] FIG. 16 is a section view of a portion of the golf club
shaft assembly illustrated in FIG. 15.
[0030] FIG. 17 is a partial section view of a portion of a golf
club in accordance with one embodiment of a present invention.
DETAILED DESCRIPTION
[0031] The following is a detailed description of the best
presently known modes of carrying out the inventions. This
description is not to be taken in a limiting sense, but is made
merely for the purpose of illustrating the general principles of
the inventions. Additionally, although the present inventions are
described in the context of fiber reinforced resin composite golf
club shafts because the inventions are particularly well suited to
such shafts, the inventions are not so limited and are applicable
to a wide variety of golf club shafts, including those currently
available and those yet to be developed.
[0032] The exemplary golf club 10 illustrated in FIGS. 1-3C
includes a shaft 100 has tip section 102, a grip section 104, and a
main section 106 between the tip section and the grip section. The
tip end of the shaft 100 is identified by reference numeral 108 and
the butt end is identified by reference numeral 110. Although the
present inventions are not so limited, the exemplary shaft 100 is a
tapered fiber reinforced resin composite shaft. To that end, the
shaft 100 is defined by a wall 112 that is circular in
cross-section, from the tip end 108 to the butt end 110, and has an
inner surface 114. Other suitable shafts include, but are not
limited to, shafts with other shapes (e.g., shafts that include
parallel tip or grip sections) and shafts formed from other
materials (e.g., steel and lightweight metal such as titanium,
aluminum and alloys). The exemplary shaft 100 also has a
center-of-percussion COP and a flex point FP.
[0033] A grip 116 covers the shaft grip section 104 and an end cap
118 covers the butt end 110. The illustrated grip 116 and end cap
118 arrangement may, in other implementations, be replaced by a
continuous, integrally formed grip that covers both the shaft grip
section 104 and butt end 110.
[0034] A club head 200 is carried on the tip section 102 of the
shaft 100. Although the present inventions are not limited to any
particular golf club configurations, the exemplary golf club 10 is
a "driver" and the club head 200 is a driver type club head. The
present inventions are, however, equally applicable to any and all
golf clubs including, but not limited to, all "woods," "irons,"
"wedges" and "putters."
[0035] A shaft insert (or "insert"), which is generally represented
by reference numeral 300 (or 300a in FIG. 17), may be permanently
secured to the shaft 100 to form a shaft assembly 12. As discussed
in greater detail below, the insert 300 is permanently secured to
the shaft 100 in such a manner that less than all of the insert, or
no portion of the insert at all, is itself bonded to the shaft. Put
another way, the insert 300 is permanently partially secured to the
shaft 100. The insert 300 will, over its entire length, contribute
to the reduction of impact vibrations and deformation, but will do
without substantially increasing the longitudinal and/or torsional
stiffness of the shaft. The substantial increase in longitudinal
and/or torsional shaft stiffness is avoided, in those portions of
the insert 300 that are not bonded to the shaft, because the shaft
100 can move relative to the insert as the shaft bends and
twists.
[0036] It should be noted that, as used herein, a portion of one
structure is "bonded" to a portion of another structure if the two
portions abut (or face) one another and there is some
instrumentality (e.g., a layer of adhesive) that fixedly secures
the abutting portions. Other portions of the same two structures
may abut one another, but are not "bonded" to one another, if there
is no adhesive (or other securing instrumentality) therebetween,
despite the fact that they may remain adjacent to one another as a
result of the bond between other portions of the structures. Such
portions are referred to herein as "non-bonded" structure. This
aspect of the present invention is discussed in greater detail
below with reference to FIGS. 4-8. It should also be noted that, as
used herein, one structure is "permanently" secured to another
structure if the structures may not be separated from one another
without destruction of one or more the structures and/or
destruction of the instrumentality (e.g., an adhesive bond)
securing the structures to one another. For example, a lock that is
configured to be unlocked as desired so that the associated
structures can be separated does not "permanently" secure the
structures to one another.
[0037] Referring to FIGS. 2-3C, the exemplary insert 300 is a
tapered tube that is defined by a wall 302 which is circular in
cross-section, from the tip end 304 to the butt end 306, and has an
outer surface 308. A relatively small portion of the insert outer
surface 308 is bonded to the shaft inner surface 114 with a layer
of permanent adhesive 310 that is located between the shaft and
insert. The exemplary insert 300 is also sized and shaped such that
the insert butt end 306 is within the main section 106 of the shaft
100 and the insert tip end 304 is within or near the tip section
102. In particular, and referring more specifically to FIG. 2, the
exemplary insert 300 is sized and shaped such that the insert will
be located between the shaft flex point FP (i.e., the point of
maximum bending when axial force is applied to the shaft at the tip
and butt ends) and the shaft tip end 108 (e.g., six inches from the
tip end). Other insert locations may also be employed in those
instances where the designer intends to alter the characteristics
of the shaft 100. For example, the insert 300 may be positioned
such that the insert butt end 306 is above (in the illustrated
orientation) the flex point FP or the insert may be associated with
the grip section 104 (FIG. 17). The butt end 306 of the insert 300
may be located in the shaft grip section and the tip end 304 of the
insert may be located in the shaft tip section.
[0038] The perimeter of the insert outer surface 308 and the
perimeter of the associated portions of the shaft inner surface 118
are extremely close in shape and dimension in the illustrated
implementations. For example, and referring to FIG. 2, the insert
300 will typically have the same taper as the shaft 100 and the
insert tip end 304 will have an outer diameter that is
substantially the same as the diameter of the shaft inner surface
114 at the point at which the insert tip end is to be located. The
insert tip end 304 will, of course, be prevented from moving beyond
this point because the inner diameter of the tapered shaft 100
beyond this point will be smaller than the outer diameter of the
insert tip end. The outer diameter of the insert 300 may also be
substantially the same as the inner diameter of the associated
portion of the shaft 100 from the insert tip end 304 to the insert
butt end 306. In other implementations, the taper of insert may be
slightly different than the taper of the shaft and, as a result,
there will be a small gap between the outer surface of the insert
and the inner surface of the shaft. Here, the insert may be
configured such that the tip end of the insert touches the inner
surface of the shaft (in some instances with nothing therebetween)
or the butt end of the insert touches the inner surface of the
shaft (in some instances with nothing therebetween).
[0039] Referring to FIG. 4, and as alluded to above, only a
relatively small portion of the insert 300 is bonded to the shaft
100. The length (in the longitudinal direction) of the bonded
portion of insert 300, i.e., the length that is bonded to the shaft
100 with the adhesive 310, is represented by reference character
L.sub.B and the length of the non-bonded portion of the insert 300,
i.e., the length that abuts but is not itself bonded to the shaft
100 with the adhesive 310, is represented by reference character
L.sub.NB. Put another way, the length L.sub.B of the bonded portion
of the insert 300 is equal to the length of the adhesive layer 310
or other bonding instrumentality. The length of the relatively
small bonded portion may range from about 0.5% to about 50% of the
length of the insert 300 (i.e., the length L.sub.NB of the
non-bonded portion may range from about 50% to about 99.5% of the
length of the insert). Other ranges for the length L.sub.B of the
relatively small bonded portion may include, but are not limited to
about 0.5% to about 25% of the length of the insert 300 (i.e., the
length L.sub.NB of the non-bonded portion may range from about 75%
to about 99.5% of the length of the insert), about 0.5% to about
10% of the length of the insert (i.e., the length L.sub.NB of the
non-bonded portion may range from about 90% to about 99.5% of the
length of the insert), and about 0.5% to about 5% of the length of
the insert (i.e., the length L.sub.NB of the non-bonded portion may
range from about 95% to about 99.5% of the length of the insert).
The length of the bonded portion of a 12-inch insert 300 may,
therefore, range from about 1/16 inch to 6 inches. For purposes of
comparison, the bonded and non-bonded lengths L.sub.B and L.sub.NB
in the shaft assembly 12 (FIG. 4) are about 1% and 99%,
respectively, of the total length of insert 300 in FIG. 4, while
the bonded and non-bonded lengths L.sub.B and L.sub.NB are about
50% each in the shaft assembly 12a (FIG. 5).
[0040] In some embodiments (e.g., the embodiments illustrated in
FIGS. 1-5), the layer of adhesive 310 (or other bonding
instrumentality) begins at or near the insert butt end 306 and
extends continuously toward the insert tip end 304, while the
non-bonded portion of the insert begins at the tip end of the
insert and extends toward the butt end. The present inventions are
not, however, limited to continuous bonding. Referring for example
to the shaft assembly 12b illustrated in FIG. 6, the adhesive 310
(or other bonding instrumentality) may be provided in two (or more)
longitudinally spaced locations. Here, bonded length L.sub.B is the
total length spanned by the adhesive (or other bonding
instrumentality), including the gaps therebetween, and the
non-bonded length L.sub.NB is the remainder of the insert length
and extends from the insert tip end 304 to the edge of the adhesive
310.
[0041] The present inventions are also not limited to bonds that
extend to the insert butt end 306. For example, the adhesive 310 in
FIGS. 1-4 may be moved a short distance toward the insert tip end
304. Referring to the exemplary shaft assembly 12c illustrated in
FIG. 7, the adhesive 310 (or other bonding instrumentality) may be
located at the tip end 304 instead of the butt end 306.
Alternatively, the exemplary shaft assembly 12d illustrated in FIG.
8 includes adhesive 310 (or another bonding instrumentality) that
is located between the tip end 304 and butt end 306. Here, the
non-bonded length L.sub.NB is sum of the non-bonded lengths
L.sub.NB1 and L.sub.NB2 on either side of the bond.
[0042] Although the present inventions are not limited to any
particular permanent adhesive, the exemplary permanent adhesive 310
is epoxy. Other suitable adhesives include, but are not limited to,
polyurethane, acrylic, cyanoacrylate adhesives. It should also be
noted that instrumentalities other than adhesives may also be used
to perform the permanent bonding function. Such bonding
instrumentalities include, but are not limited to, ultrasonic
welds. Here, the insert and the shaft may be bonded directly to one
another, or a thin plastic tube (which melts during the welding
process) may be positioned over the butt end of the insert. Other
instrumentalities include a thin strip of a polymeric material,
such as plastic, nylon, PVC, neoprene, polyurethane and rubber,
with a permanent adhesive on both sides. The strip is too thin
(e.g., less than 1 mm thick) to act as an effective vibration
damper. It should also be noted that the bond need not extend
continuously around the circumference of the insert. For example,
the layer of adhesive could consist of spaced strips, dots,
spirals, or the like.
[0043] One exemplary method of permanently bonding a portion of the
insert 300 to the shaft with epoxy adhesive is illustrated in FIG.
9. First, a layer of epoxy adhesive 310 is applied to outer surface
308 at or near the butt end 306 through the use of a brush, squeeze
or a carrier tape. The epoxy is then cooled to about 15.degree. F.
for 15-30 minutes, which freezes the epoxy and eliminate the
tackiness of the epoxy. The insert 300 is then placed into the
shaft 100 at room temperature and is moved toward the shaft tip end
108 until the outer diameter of the insert is equal to the inner
diameter of the shaft along the length of the insert, thereby
preventing further movement of the insert toward the shaft tip end.
A tool 400, which consists of a weight 402 (e.g., a 20-50 g weight)
and a rod 404 attached to the weight, is then inserted into the
shaft 100 as shown in FIG. 9. The tool 400 holds the insert 300
down as the epoxy 310 melts (and returns to its emulsified state)
and then hardens to form the above-described permanent bond. The
rod 404 is then used to remove the weight 402 from the completed
shaft assembly 12.
[0044] Turning to FIG. 10, another exemplary instrumentality that
performs the permanent bonding function is a weld 312 in the
exemplary shaft assembly 12e. The weld 312 may be formed by heating
respective portions of the shaft 100 and insert 300 along the
bonded length L.sub.B with, for example, an ultrasonic welding
device WD.
[0045] In the embodiments illustrated in FIGS. 1-10, a portion of
the insert 300 is bonded to the shaft 100, thereby permanently
securing the insert to the shaft. In other embodiments, no portion
of the insert 300 is bonded to the shaft 100, yet the insert is
nevertheless permanently secured to the shaft. Referring to the
exemplary insert assembly 12f illustrated in FIGS. 11-13, another
method of permanently securing the insert 300 to the shaft 100
involves the use of a plug 500 that is bonded to the inner surface
114 of the shaft 100. The plug 500, which may be hollow (as shown)
or solid, includes a wide portion 502 and a narrow portion 504. The
wide portion 502 engages the insert butt end 306 and the narrow
portion 504 is located within the insert 300. The plug 500 may be
formed from a polymeric material, such as plastic, ABS, PVC, Nylon,
acrylic, Delrin, or any other suitable material. The axial length
of the wide portion 502 may, in some implementations, be about 1/16
inch to about 1/2 inch and the narrow portion 504 may be about the
same length or less.
[0046] During assembly, the insert 300 is placed in the shaft 100
and moved toward the shaft tip end 108 until the outer diameter of
the insert is equal to the inner diameter of the shaft, thereby
preventing further movement of the insert toward the shaft tip end.
Movement of the insert 300 toward the shaft butt end 110 is
prevented by the plug 500. To that end, the plug 500 may be coated
with a layer of adhesive 310. The adhesive 310 is used to
permanently bond the relatively wide portion 502 to the shaft inner
surface, and to permanently bond the narrow portion to the insert
inner surface 314. The adhesive cooling/warming technique and tool
400 described above may be used here as well. Alternatively, the
adhesive 310 may be omitted from the plug narrow portion 504 (FIG.
14). The adhesive 310 may also be omitted completely and a bonding
technique, such as ultrasonic welding, may be used to permanently
bond the plug to the shaft. In any case, once bonded, the entire
length of the insert 300 will be the non-bonded length
L.sub.NB.
[0047] Referring to FIGS. 15 and 16, the plug 500a in the exemplary
shaft assembly 12g is similar to plug 500 and is used to
permanently secure the insert 300 to the shaft 100 in the manner
described above. Here too, the plug 500a prevents the insert 300
from moving toward the butt end of the shaft 100 and the entire
length of the insert will be the non-bonded length L.sub.NB. The
plug 500a does not, however, include a narrow portion and a wide
portion. The plug 500a, which may be hollow (as shown) or solid, is
simply sized to fit into the shaft 100 and abut the butt end 306 of
the insert 300 in the manner illustrated in FIG. 16. A layer of
adhesive 310 permanently secures the plug 500a to the shaft
100.
[0048] As alluded to above, inserts may be configured such that
they will be located in portions of the shaft other than that
illustrated in FIG. 4. To that end, and as illustrated for example
in FIG. 17, the golf club 10a includes a shaft assembly 12h with a
shaft 100 and an insert 300a that is identical to insert 300 but
for dimensions. The insert 300 is permanently secured to the shaft
100 at a location that includes portions of the grip section 104
and main section 106 for purposes of, for example, adjusting the
bending characteristics of the shaft 100.
[0049] Turning to the dimensions and materials, the length of the
insert 300 will typically range from about 4 inches to about 30
inches and the exemplary insert 300 is about 12 inches in length.
The outer diameter may, depending on the length of the insert and
the size of the associated golf club shaft, range from about 4 mm
to 10 mm at the tip end to about 7 mm to 13 mm at the butt end. The
length of the insert 300a will typically range from about 6 inches
to about 35 inches and the exemplary insert 300a is about 15 inches
in length. The outer diameter of the insert 300a may, depending on
the length of the insert and the size of the associated golf club
shaft, range from about 5 mm to 11 mm at the tip end to about 8 mm
to 14 mm at the butt end.
[0050] The insert lengths may also be a function of intended
position. For example, the insert 300 may be configured to extend
much closer to the shaft tip end 108 and/or to the shaft butt end
110. The insert 300a may be re-configured such that its tip end 304
is in the location illustrated in FIG. 17, while the butt end 306
is either located closer to, or is located further from, the main
section 106 (yet still within the grip section 104). The butt end
306 of the insert 300a may also be located within the shaft main
section 106. Depending on the intended adjustment to the shaft 100,
the insert assembly 300a may be secured within the shaft without
the insert 300, both inserts may be secured within the shaft, or
the insert 300 may secured within the shaft without the insert
300a.
[0051] In those instances where the golf club shaft is not tapered
from tip end to butt end, e.g. in those instances where the shaft
has a tapered main section and cylindrical tip and/or grip
sections, the insert may be shaped accordingly. For example, the
insert may be tapered over its entire length and dimensioned so as
to reside only in the shaft main section, or the insert may be
tapered over the substantial majority of its length and have a
short cylindrical section that is coextensive with a small portion
of the cylindrical grip section or tip section of the shaft.
[0052] Turning to materials, the inserts 300 and 300a may be formed
from relatively light weight materials, such as graphite or a
polymer. A typical weight is about 15 grams or less. Different
portions of the inserts may also be made from different materials
if desired. The inserts may be manufactured to the desired lengths
or manufactured to set lengths and then cut as necessary.
Dimensional marking may be provided to facilitate accurate cuts.
Suitable graphite insert manufacturing techniques include
sheet-wrapping, filament-winding, and internal bladder molding,
among other appropriate techniques. For example, one or more layers
of Toray graphite material (e.g. Toray T700, M30, M40J, M46J or
M50J) may be sheet-wrapped around a layer of light weight (e.g.
about 100 g/m.sup.2 or less) scrim or a layer of graphite pre-preg.
Suitable polymer manufacturing techniques include injection
molding. The outer surface of the inserts 300 and 300a may, in some
instances, be coated with a coating that improves the fit between
the insert and the golf club shaft 100 and reduces noise that may
result from the engagement of the insert and the shaft. One example
of such a coating is a polyurethane based coating. Additional
details concerning inserts is provided in U.S. Pat. Nos. 7,479,069,
7494,423 and 7,500,921.
[0053] With respect to wall thickness (i.e. the difference between
the inner diameter and the outer diameter), the inserts 300 and
300a may have a constant wall thickness or one that varies. In the
illustrated implementations, 0.1 mm to 1.0 mm.
[0054] Although the present inventions have been described in terms
of the preferred embodiments above, numerous modifications and/or
additions to the above-described preferred embodiments would be
readily apparent to one skilled in the art. By way of example, but
not limitation, the present inventions include golf clubs (e.g. a
shaft and a club head) in combination with the shaft/insert
combinations described above and defined by the claims below. The
golf clubs may also include a grip and an end cap. It is intended
that the scope of the present inventions extend to all such
modifications and/or additions.
* * * * *