U.S. patent application number 11/152036 was filed with the patent office on 2006-02-02 for composite ball bat with constrained layer dampening.
Invention is credited to Dewey Chauvin, Hsing-Yen Chuang, William B. Giannetti.
Application Number | 20060025253 11/152036 |
Document ID | / |
Family ID | 44686362 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060025253 |
Kind Code |
A1 |
Giannetti; William B. ; et
al. |
February 2, 2006 |
Composite ball bat with constrained layer dampening
Abstract
A composite ball bat includes one or more dampening elements
located primarily at or near one or more vibration anti-nodes of
the ball bat to provide vibration dampening and improved bat
"feel." The dampening elements may be made of viscoelastic and/or
elastomeric materials, and/or other vibration-attenuating
materials, and may be located in the barrel, the handle, and/or the
tapered or transition region of the ball bat.
Inventors: |
Giannetti; William B.; (Van
Nuys, CA) ; Chuang; Hsing-Yen; (Studio City, CA)
; Chauvin; Dewey; (Simi Valley, CA) |
Correspondence
Address: |
PERKINS COIE LLP
POST OFFICE BOX 1208
SEATTLE
WA
98111-1208
US
|
Family ID: |
44686362 |
Appl. No.: |
11/152036 |
Filed: |
June 14, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11078782 |
Mar 11, 2005 |
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11152036 |
Jun 14, 2005 |
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10903493 |
Jul 29, 2004 |
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11078782 |
Mar 11, 2005 |
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11034993 |
Jan 12, 2005 |
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11152036 |
Jun 14, 2005 |
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10903493 |
Jul 29, 2004 |
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11034993 |
Jan 12, 2005 |
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Current U.S.
Class: |
473/567 |
Current CPC
Class: |
A63B 60/54 20151001;
A63B 2102/18 20151001; A63B 60/00 20151001; A63B 59/50
20151001 |
Class at
Publication: |
473/567 |
International
Class: |
A63B 59/00 20060101
A63B059/00 |
Claims
1. A composite ball bat, including a barrel, a handle, and a
transition section joining the barrel to the handle, comprising: at
least one dampener in at least one of the barrel, the handle, and
the transition section, with substantially each of the at least one
dampeners located substantially at an anti-node of a vibration mode
of the ball bat.
2. The ball bat of claim 1 wherein the at least one dampener is
bonded to surrounding composite material in the ball bat.
3. The ball bat of claim 1 wherein the at least one dampener is
0.008 to 0.020 inches thick.
4. The ball bat of claim 1 wherein the at least one dampener
comprises at least one of a viscoelastic and an elastomeric
material.
5. The ball bat of claim 1 wherein the at least one dampener
comprises a plurality of discrete dampeners, with substantially
each of the discrete dampeners located substantially at a single
anti-node of a vibration mode of the ball bat.
6. The ball bat of claim 1 wherein the at least one dampener
comprises a plurality of dampeners arranged in parallel at a
plurality of radial locations substantially at an anti-node of a
vibration mode of the ball bat.
7. The ball bat of claim 1 wherein the at least one dampener
comprises a plurality of dampeners arranged longitudinally in
series at approximately the same radial location in the ball
bat.
8. The ball bat of claim 1 wherein the at least one dampener
comprises a plurality of dampeners located substantially at a
plurality of anti-nodes of at least one vibration mode of the ball
bat.
9. The ball bat of claim 1 wherein at least one dampener is located
substantially at the anti-node of the first bending mode of the
ball bat.
10. The ball bat of claim 1 wherein at least one dampener is
located substantially at the anti-node of the first hoop mode of
the ball bat.
11. The ball bat of claim 1 wherein the barrel comprises at least
two walls, and wherein at least one dampener is located in each of
the barrel walls.
12. The ball bat of claim 11 wherein the at least two walls of the
barrel are separated by at least one ISCZ, and wherein at least one
dampener is positioned against the at least one ISCZ.
13. The ball bat of claim 1 wherein composite material in the ball
bat is fused at at least one end to form a continuous load path
between the at least one dampener and the composite material.
14. The ball bat of claim 1 wherein the at least one dampener
comprises a material having an axial elastic modulus that is 0.01
to 50% of an axial elastic modulus of neighboring composite
material in the ball bat.
15. The ball bat of claim 1 wherein the at least one dampener
comprises a material having an axial elastic modulus that is 0.05
to 10% of an axial elastic modulus of neighboring composite
material in the ball bat.
16. The ball bat of claim 1 wherein the at least one dampener
comprises a material having an axial elastic modulus that is 0.10
to 5.0% of an axial elastic modulus of neighboring composite
material in the ball bat.
17. A composite ball bat, comprising: a discrete first vibration
attenuation element located substantially at the anti-node of the
first bending mode of the ball bat; and a discrete second vibration
attenuation element located substantially at the anti-node of the
first hoop mode of the ball bat.
18. The ball bat of claim 17 further comprising at least one
discrete additional vibration attenuation element, with each of the
at least one discrete additional vibration attenuation elements
located substantially at one of the anti-nodes of the second
bending mode of the ball bat.
19. The ball bat of claim 17 wherein at least one of the first and
second vibration attenuation elements is bonded to surrounding
composite material in the ball bat.
20. The ball bat of claim 17 wherein at least one of the first and
second vibration attenuation elements comprises at least one of a
viscoelastic and an elastomeric material.
21. The ball bat of claim 17 wherein the first and second vibration
attenuation elements each comprise at least one material having a
lower axial elastic modulus than an axial elastic modulus of
neighboring composite material in the ball bat.
22. A composite ball bat, comprising: at least one discrete primary
dampening element located substantially at the anti-node of the
first bending mode of the ball bat; and at least one discrete
secondary dampening element located substantially at one of the
anti-nodes of the second bending mode of the ball bat.
23. The ball bat of claim 22 wherein the at least one discrete
secondary dampening element comprises at least a first dampener
positioned primarily at the anti-node of the second bending mode
located in a barrel of the ball bat, and a second dampener
positioned primarily at the anti-node of the second bending mode
located in a handle of the ball bat.
24. A composite ball bat, comprising: a plurality of discrete means
for dampening vibration, with substantially each of the discrete
dampening means located substantially at a vibration anti-node in
the ball bat and having a lower axial elastic modulus than that of
neighboring material in the ball bat.
Description
[0001] This application is a Continuation-In-Part of U.S. patent
application Ser. No. 11/078,782, filed Mar. 11, 2005, which is a
Continuation-In-Part of U.S. patent application Ser. No.
10/903,493, filed Jul. 29, 2004. This application is also a
Continuation-In-Part of U.S. patent application Ser. No.
11/034,993, filed Jan. 12, 2005, which is a Continuation-In-Part of
U.S. patent application Ser. No. 10/903,493, filed Jul. 29, 2004.
Each of the above-listed patent applications is incorporated herein
by reference.
BACKGROUND
[0002] When a baseball bat or softball bat impacts a ball, energy
is transferred from the ball to the bat, in the form of deformation
(radial and transverse), noise, and heat. When the ball strikes a
location of the bat that is in the proximity of a primary vibration
node, and/or at the intersection of a primary vibration node and
the center of percussion (COP) of the bat, the bat experiences
little or no vibration. This is known as a "sweet spot" hit.
Alternatively, when the ball strikes a location of the bat that is
not in the vicinity of a primary vibration node or the COP, the bat
deforms into its fundamental and harmonic mode shapes. The
magnitude of this deformation is a direct function of the mode that
is excited and the distance from the vibration node and the COP to
the impact location. If the acceleration of the bat into its mode
shapes is significantly high, and is at a specific frequency, the
bat will vibrate and produce shock waves.
[0003] Shock waves travel at a high velocity and, depending upon
their energy, can actually sting a player's hands. Sting typically
results from displacements in the bat handle caused by rigid body
rotations resulting from impact away from the COP, and/or from
modal vibrations caused by impact away from the primary vibration
nodes of the ball bat. Impacts of this nature are commonly referred
to as "off-center hits," because the "sweet spot" of a bat barrel
is typically located at approximately the center of its length
where the COP and the first primary vibration node are in close
proximity to one another. The sting resulting from off-center hits
may be distracting and painful to the player, and is therefore
undesirable. To minimize sting, and improve the "feel" of the bat,
shock waves resulting from off-center hits must be absorbed or
otherwise attenuated prior to reaching the bat's handle.
SUMMARY
[0004] In a composite ball bat, one or more dampening elements are
located primarily at or near one or more vibration anti-nodes of
the ball bat to provide vibration dampening and improved bat
"feel." The dampening elements may be made of viscoelastic and/or
elastomeric materials, and/or other vibration-attenuating
materials, and may be located in the barrel, the handle, and/or the
tapered or transition region of the ball bat.
[0005] Other features and advantages of the invention will appear
hereinafter. The features of the invention described above can be
used separately or together, or in various combinations of one or
more of them. The invention resides as well in sub-combinations of
the features described.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] In the drawings, wherein the same reference number indicates
the same element throughout the several views:
[0007] FIG. 1 is a side view of a ball bat.
[0008] FIG. 2 is a partial sectional view of Section X of FIG.
1.
[0009] FIG. 3A is a magnified view of Section Y of FIG. 2,
according to one embodiment.
[0010] FIG. 3B is a magnified view of Section Y of FIG. 2,
according to another embodiment.
[0011] FIG. 3C is a magnified view of Section Y of FIG. 2,
according to another embodiment.
[0012] FIG. 4 is a side view of a ball bat showing the conceptual
locations of the predominant vibration anti-nodes of the ball bat,
according to one embodiment.
DETAILED DESCRIPTION OF THE DRAWINGS
[0013] Various embodiments of the invention will now be described.
The following description provides specific details for a thorough
understanding and enabling description of these embodiments. One
skilled in the art will understand, however, that the invention may
be practiced without many of these details. Additionally, some
well-known structures or functions may not be shown or described in
detail so as to avoid unnecessarily obscuring the relevant
description of the various embodiments.
[0014] The terminology used in the description presented below is
intended to be interpreted in its broadest reasonable manner, even
though it is being used in conjunction with a detailed description
of certain specific embodiments of the invention. Certain terms may
even be emphasized below; however, any terminology intended to be
interpreted in any restricted manner will be overtly and
specifically defined as such in this detailed description
section.
[0015] Turning now in detail to the drawings, as shown in FIG. 1, a
baseball or softball bat 10, hereinafter collectively referred to
as a "ball bat" or "bat," includes a handle 12, a barrel 14, and a
tapered section or transition region 16 joining the handle 12 to
the barrel 14. The free end of the handle 12 includes a knob 18 or
similar structure. The barrel 14 is preferably closed off by a
suitable cap, plug, or other end closure 20. The interior of the
bat 10 is preferably hollow, which facilitates the bat 10 being
relatively lightweight so that ball players may generate
substantial bat speed when swinging the bat 10.
[0016] The ball bat 10 preferably has an overall length of 20 to 40
inches, more preferably 26 to 34 inches (a 34 inch bat is shown in
FIG. 4 by way of example only). The overall barrel diameter is
preferably 2.0 to 3.0 inches, more preferably 2.25 to 2.75 inches.
Typical bats have diameters of 2.25, 2.625, or 2.75 inches. Bats
having various combinations of these overall lengths and barrel
diameters, as well as any other suitable dimensions, are
contemplated herein. The specific preferred combination of bat
dimensions is generally dictated by the user of the bat 10, and may
vary greatly between users.
[0017] The bat barrel 14 may be a single-wall or a multi-wall
structure. If it is a multi-wall structure, the barrel walls may
optionally be separated by one or more interface shear control
zones (ISCZs), as described in detail in incorporated U.S. patent
application Ser. No. 10/903,493. Any ISCZ used preferably has a
radial thickness of approximately 0.001 to 0.010 inches, more
preferably 0.005 to 0.006 inches. Any other suitable size ISCZ may
alternatively be used.
[0018] An ISCZ may include a bond-inhibiting layer, a friction
joint, a sliding joint, an elastomeric joint, an interface between
two dissimilar materials (e.g., aluminum and a composite material),
or any other suitable element or means for separating the barrel
into "multiple walls." If a bond-inhibiting layer is used, it is
preferably made of a fluoropolymer material, such as Teflon.RTM.
(polyfluoroethylene), FEP (fluorinated ethylene propylene), ETFE
(ethylene tetrafluoroethylene), PCTFE
(polychlorotrifluoroethylene), or PVF (polyvinyl fluoride), and/or
another suitable material, such as PMP (polymethylpentene), nylon
(polyamide), or cellophane.
[0019] In one embodiment, one or more ISCZs may be integral with,
or embedded within, layers of barrel material, such that the barrel
14 essentially acts as a one-piece/multi-wall construction. In such
a case, the barrel layers at at least one end of the barrel are
preferably blended together to form the one-piece/multi-wall
construction. The entire ball bat 10 may also be formed as "one
piece." A one-piece bat design, as used herein, generally refers to
the barrel 14, the tapered section 16, and the handle 12 of the
ball bat 10 having no gaps, inserts, jackets, or bonded structures
acting to appreciably thicken the barrel wall(s). In such a design,
the distinct laminate layers are preferably integral to the barrel
structure so that they all act in unison under loading conditions.
To accomplish this one-piece design, the layers of the bat 10 are
preferably co-cured, and are therefore not made up of a series of
connected tubes (inserts or jackets) each having a separate wall
thickness at the ends of the tubes.
[0020] The blending of the barrel walls into a one-piece
construction, around one or more ISCZs, like tying the ends of a
leaf spring together, offers a stable, durable assembly, especially
for when impact occurs at the extreme ends of the barrel 14.
Bringing multiple laminate layers together assures that the system
acts as a unitized structure, with no one layer working independent
of the others. By redistributing stresses to the extreme ends of
the barrel, local stresses are reduced, resulting in increased bat
durability. In an alternative multi-wall embodiment, the bat and/or
barrel layers are not blended together at either end.
[0021] The one or more barrel walls are preferably each made up of
one or more composite plies. The composite materials that make up
the plies are preferably fiber-reinforced, and may include fibers
of glass, graphite, boron, carbon, aramid (e.g., Kevlar.RTM.),
ceramic, metallic, and/or any other suitable structural fibrous
materials, preferably in epoxy form or another suitable form. Each
composite ply preferably has a thickness of approximately 0.002 to
0.060 inches, more preferably 0.005 to 0.008 inches. Any other
suitable ply thickness may alternatively be used.
[0022] In one embodiment, the bat barrel 14 may comprise a hybrid
metallic-composite structure. For example, the barrel may include
one or more walls made of composite material(s), and one or more
walls made of metallic material(s). Alternatively, composite and
metallic materials may be interspersed within a given barrel wall.
In another embodiment, nano-tubes, such as high-strength carbon
nano-tube composite structures, may alternatively or additionally
be used in the barrel construction.
[0023] FIG. 2 illustrates an interior section of one embodiment of
a bat barrel 14 including one or more vibration dampening elements,
or dampeners 30, incorporated into the composite layers 32 of the
bat barrel 14. The one or more dampeners 30 may be made of any
suitable vibration attenuating or dampening material(s), i.e., any
material(s) having a lower axial elastic modulus than that of the
neighboring or surrounding materials in the ball bat. In one
embodiment, one or more of the dampeners 30 may have an axial
elastic modulus that is 0.01 to 50%, or 0.02 to 25%, or 0.05 to
10%, or 0.10 to 5.0%, or 0.50 to 2.5%, or 0.75 to 1.25%, of the
axial elastic modulus of the neighboring or surrounding materials
in the ball bat 10. Any material having a lower elastic modulus
than the neighboring or surrounding materials in the ball bat 10
may be used, however.
[0024] In one embodiment, one or more of the dampeners 30 are made
of one or more viscoelastic and/or elastomeric materials, such as
elastomeric rubber, silicone, gel foam, or other similar materials.
The dampeners 30 may alternatively or additionally be made of any
other suitable dampening materials, including but not limited to
PBO (polybenzoxazole), UHMWPE (ultra high molecular weight
polyethylene, e.g., Dyneema.RTM.), fiberglass, dacron.RTM.
("polyethylene terephthalate"--PET or PETE), nylon.RTM.
(polyamide), certran.RTM., Pentex.RTM., Zylon.RTM., Vectran.RTM.,
and/or aramid, that are effective at dissipating or otherwise
attenuating vibrational energy relative to the neighboring or
surrounding materials in the ball bat 10.
[0025] Thus, depending on the one or more materials that are used
to form the structural layers of the ball bat 10, a wide variety of
dampening materials (relative to those neighboring or surrounding
structural materials) may be used in the ball bat 10. For example,
a soft rubber dampening material may have an axial elastic modulus
of approximately 10,000 psi, whereas a "dampening" material such as
aramid may have an axial elastic modulus of approximately
12,000,000 psi. While the dampening effect of aramid is
significantly less than that of a typical soft rubber material, it
may still have an appreciable dampening effect on surrounding or
neighboring structural bat material(s) having an even higher axial
elastic modulus, and it may provide increased durability relative
to softer materials. Accordingly, materials having a relatively
high axial elastic modulus, such as aramid, may be used as
effective dampeners in some ball bat constructions.
[0026] Each dampener 30 may form part of one or more of the
composite layers within the ball bat 10, or may be included as a
separate layer. Each dampener 30 may also optionally be sandwiched
between neighboring composite layers, as shown in FIG. 3A. Each
dampener 30 is preferably bonded, fastened, or otherwise attached
or fused to the surrounding composite material in the ball bat 10.
The composite material at one or both ends of the ball bat 10,
and/or at locations adjacent to one or both ends of the dampener
30, may also be fused or blended together to provide a continuous
load path between the bat structure and the dampener 30.
[0027] In the embodiment illustrated in FIG. 3A, the dampener 30 is
shown located substantially at the mid-plane of a barrel wall,
where shear stresses are the highest, by way of example only. One
or more dampeners 30 may alternatively or additionally be located
anywhere within the radial thickness of the one or more barrel
walls that make up the bat barrel 14, or within any of the other
regions of the ball bat 10. FIG. 3B, for example, illustrates an
embodiment in which a dampener 30 is located at an inner portion of
a barrel wall. In this embodiment, at least one inner layer of
composite material preferably confines the dampener 30 within the
barrel structure, and preferably extends at least one inch or more
beyond each end of the dampener 30. In another embodiment, one or
more dampeners 30 may additionally or alternatively be similarly
positioned at an outer portion of one or more barrel walls, or
other bat regions.
[0028] FIG. 3C shows an embodiment in which multiple dampeners 30
are positioned in series within a single layer at the inner portion
of a barrel wall. In another embodiment, multiple dampeners 30 may
additionally or alternatively be located in parallel, i.e.,
positioned at approximately the same longitudinal location of the
ball bat 10 at different radial locations within the barrel 14 or
other bat region. If the ball bat 10 includes a multi-wall barrel
14, and/or one or more ISCZs, dampeners 30 may be located in one or
more of the barrel walls, at any suitable locations, including at
the plane between adjacent barrel walls and/or against one or both
sides of an ISCZ. Thus, one or more dampeners 30 may be located
anywhere within the barrel 14, the transition region 16, and/or the
handle 12 of the ball bat 10 to achieve a desired response, as
further described below.
[0029] The one or more dampeners 30 may each have any suitable
length and/or thickness. For example, a dampener 30 may be 0.25 to
5.00 inches in length (or longer, if desired), and 0.004 to 0.100
inches thick (or any other suitable thickness). In one embodiment,
each dampener has a thickness of 0.008 to 0.020 inches. While the
dampeners 30 may be any conceivable size, and could theoretically
run approximately the entire length of the ball bat 10, it is
preferable to incorporate one or more discrete dampeners of smaller
size, at one or more strategic locations, to selectively dampen
vibration while not adding substantial weight to, or significantly
lowering the durability of, the ball bat 10.
[0030] FIG. 4 illustrates one embodiment of a 34 inch ball bat 10,
including the locations of the predominant vibration anti-nodes of
the ball bat 10. An anti-node is a point in a standing wave at
which the amplitude is a maximum. Thus, under impact conditions,
the vibration anti-nodes of the ball bat 10 are located at the
regions of maximum deflection (specific to the mode shape of the
bat in vibration) in the ball bat 10. The vibration anti-nodes, as
used herein, generally refer to anti-nodes of the bending and/or
hoop modes of the ball bat 10. The locations of one or more of
these vibration anti-nodes, which are readily determinable by those
skilled in the art, may vary depending on the overall dimensions
and makeup of the ball bat 10. Thus, the specific anti-node
locations illustrated in FIG. 4 are shown by way of example
only.
[0031] In one embodiment, one or more vibration dampeners 30 are
located at, and are optionally substantially centered about, one or
more of the vibration anti-nodes in the ball bat 10 to reduce the
amplitude of vibrations excited at those locations by off-center
hits. Alternatively, one or more dampeners 30 may be located
adjacent to or substantially near one or more of the vibration
anti-nodes, since deflection is also relatively high at bat regions
near the anti-nodes. Terms and phrases used herein to describe
dampener location, such as "substantially at" or "at or near,"
generally refer to the idea that a dampener is ideally located
directly at an anti-node location, but that a dampener could
alternatively or additionally be located near an anti-node to
produce a dampening effect. Thus, such language is intended to mean
that a dampener may be located directly at an anti-node, or very
close to the anti-node.
[0032] The one or more dampeners 30 reduce the amplitude of impact
reaction forces and modal vibrations by absorbing significant shear
strain energy and dissipating it into the environment in the form
of heat energy. A dampener 30 made from a viscoelastic material,
for example, dissipates energy at a lower rate (due to hysteresis)
than a typical elastic material, such that dissipation of the
impact energy occurs relatively slowly, resulting in high dampening
of the initial impact impulse.
[0033] One preferred location for a dampener 30 is at or near the
anti-node of the first bending mode (i.e., of the fundamental
harmonic) of the ball bat 10, indicated by a "1" in FIG. 4. The
anti-node of the first bending mode exhibits the largest
deformation, and the highest strain energy, of all the anti-nodes
of the principal modes. Thus, by locating one or more dampeners 30
at or near the anti-node of the first bending mode, i.e., at
approximately 19 to 21 inches from the cap end of the ball bat 10
shown in FIG. 4, a large amount of vibration energy resulting from
off-center hits may be dissipated or otherwise attenuated.
[0034] One or more dampeners 30 may also be located at or near the
anti-nodes of the second and/or third bending modes (which do not
exhibit as much deformation as does the anti-node of the first
bending mode, but which still contribute to vibrational effects) of
the ball bat 10, indicated by the numbers "2" and "3",
respectively, in FIG. 4, to suppress the second and/or third
bending modes. To suppress the second bending mode of the ball bat
10 illustrated in FIG. 4, for example, one or more dampeners 30 may
be positioned at approximately 8 to 10 inches, and/or 26 to 28
inches, from the cap end of the ball bat 10.
[0035] In another embodiment, a dampener 30 is additionally or
alternatively positioned at or near the anti-node of the
fundamental or first hoop mode, indicated by the letter "A" in FIG.
4, of the ball bat 10. Because this anti-node, which is located
approximately 4 to 8 inches from the cap end of the ball bat 10
illustrated in FIG. 4, is substantially at the intersection of the
COP and the first and second harmonic bending nodes (i.e., at the
"sweet spot" of the ball bat), minimal, if any, vibration occurs at
this location. Thus, only a minimal amount of vibration attenuation
(if any) is required at this location to prevent sting. By adding
one or more dampeners 30 at or near this "sweet spot" location,
however, the perceived size of the sweet spot generally increases,
providing improved feel for batters.
[0036] Multiple dampeners 30 may be located throughout the bat
structure, at or near any combination of the anti-nodes, to
minimize vibrations in the ball bat 10. Each of the dampeners 30 is
preferably discrete and discontinuous with respect to other
dampeners 30, and is located primarily at or near a single
anti-node. It is contemplated, however, that one or more individual
dampeners 30 could overlap two or more anti-nodes. For example, a
single dampener 30 could be positioned to overlap the anti-node "1"
of the first bending mode and the anti-node "3" of the third
bending mode located in the transition region of the ball bat
(e.g., at approximately 19-22 inches from the cap end of the ball
bat 10 illustrated in FIG. 4). To minimize the overall weight and
maintain sufficient durability of the bat structure, however, it is
generally preferred that substantially each of the dampeners 30 is
discrete and strategically positioned at or near a single vibration
anti-node. As described above, multiple dampeners may be located in
parallel, i.e., at different radial locations, at or near a given
anti-node.
[0037] The ball bat 10 may be constructed in any suitable manner.
In one embodiment, the ball bat 10 is constructed by rolling the
various layers of the bat 10 onto a mandrel or similar structure
having the desired bat shape. The one or more dampeners 30, as well
as any ISCZs, if used, are preferably strategically placed,
located, and/or oriented, as shown and described above. The one or
more dampeners 30 are preferably located at or near vibration
anti-nodes in the tapered section 16, the handle 12, and/or the
barrel 14 of the ball bat 10 to provide attenuation of vibrational
energy in the ball bat 10.
[0038] The ends of the material layers are preferably "clocked," or
offset, from one another so that they do not all terminate at the
same location before curing. Additionally, if varying layer
orientations and/or wall thicknesses are used, the layers may be
staggered, feathered, or otherwise angled or manipulated to form
the desired bat shape. Accordingly, when heat and pressure are
applied to cure the bat 10, the various layers blend together into
a distinctive "one-piece," or integral, construction. Furthermore,
during heating and curing of the composite layers, the dampeners 30
preferably fuse with the surrounding composite material and become
an integral part of the overall bat structure.
[0039] Put another way, all of the layers of the bat are "co-cured"
in a single step, and blend or terminate together at at least one
end, resulting in a single-piece structure with no gaps (at the at
least one end), such that the barrel 14 is not made up of a series
of tubes each with a separate wall thickness that terminates at the
ends of the tubes. As a result, all of the layers act in unison
under loading conditions, such as during striking of a ball. One or
both ends of the barrel 14 may terminate together in this manner to
form a one-piece barrel 14, including one or more barrel walls
(depending on whether any ISCZs are used). In an alternative
design, neither end of the barrel is blended together, such that a
multi-piece construction is formed.
[0040] The described bat construction, incorporating one or more
dampeners at or near vibration anti-node locations of the ball bat,
significantly decreases the vibrational energy transmitted to the
bat handle and the batter's hands. Accordingly, sting felt by the
batter is significantly reduced or eliminated, and the "sweet spot"
of the ball bat may be effectively increased. Dampeners may
additionally be located in specific regions of the ball bat to
provide increased flexure in those regions.
[0041] Thus, while several embodiments have been shown and
described, various changes and substitutions may of course be made,
without departing from the spirit and scope of the invention. The
invention, therefore, should not be limited, except by the
following claims and their equivalents.
* * * * *