U.S. patent application number 10/672060 was filed with the patent office on 2005-03-31 for tubular baseball bats with variable stiffened barrels.
Invention is credited to Fitzgerald, Stephen, St. Laurent, Frederic, Sutherland, Terrance William.
Application Number | 20050070384 10/672060 |
Document ID | / |
Family ID | 34376263 |
Filed Date | 2005-03-31 |
United States Patent
Application |
20050070384 |
Kind Code |
A1 |
Fitzgerald, Stephen ; et
al. |
March 31, 2005 |
Tubular baseball bats with variable stiffened barrels
Abstract
Tubular baseball bats comprised of an elongated handle portion
and a striking or barrel portion wherein the barrel portion has
variable stiffness along its length. One such bat has a
circumferential low cost, low weight stiffener generally located in
the sweetspot area designed to increase radial stiffness in a
controlled manner which results in decreasing the bat performance
to meet a changed bat performance standard and can be applied at
low cost to both used field returned bats and bats being newly
manufactured. Further, new tubular polymer composite bats can be
designed with increased radial stiffness generally located in the
sweetspot area or with radial stiffness graduated from highest,
generally in the sweetspot area, to lowest at the barrel ends. All
bats of the present invention result in calculated bat performance
to meet applicable regulatory standards while also increasing the
sweetspot size.
Inventors: |
Fitzgerald, Stephen;
(Halifax, CA) ; St. Laurent, Frederic; (Val des
Monts, CA) ; Sutherland, Terrance William; (Ottawa,
CA) |
Correspondence
Address: |
David J. French
P.O. Box 2486, Stn. "D"
Ottawa
K1P 5W6
CA
|
Family ID: |
34376263 |
Appl. No.: |
10/672060 |
Filed: |
September 29, 2003 |
Current U.S.
Class: |
473/567 |
Current CPC
Class: |
A63B 59/50 20151001;
A63B 60/00 20151001; A63B 2102/18 20151001 |
Class at
Publication: |
473/567 |
International
Class: |
A63B 059/06 |
Claims
I claim:
1. A tubular baseball bat comprising a cylindrical handle portion
for gripping, a cylindrical tubular barrel portion for striking,
and a tapered mid-section connecting said handle portion and said
barrel portion, wherein said barrel portion has variable stiffness
along its length.
2. A bat according to claim 1, wherein said variable stiffness is
achieved by adding a polymer composite material stiffener to the
said barrel portion.
3. A bat according to claim 2 wherein said polymer composite
material comprises a resin matrix encapsulating reinforcement
fibers wherein said resin is selected from the group of resin
consisting of epoxy, vinyl ester, polyester, urethane, nylon, and
mixtures thereof and wherein said reinforcement fibers are selected
from the group consisting fiberglass, graphite, carbon, aramid,
boron, nylon and mixtures thereof.
4. A bat according to claim 2 wherein said stiffener has a length
less than 50% of the said barrel portion length and adds less than
2 oz. to said bat weight.
5. A bat according to claim 2 wherein said stiffener is located
internally, and/or externally to said barrel portion, and/or
between members of double-walled or multi-walled bats, or
combinations thereof.
6. A bat according to claim 2 wherein said stiffener is bonded full
length to at least one bat barrel member.
7. A bat according to claim 1, where said stiffness is radial
stiffness.
8. A polymer composite tubular baseball bat comprising a
cylindrical handle portion for gripping, a cylindrical tubular
barrel portion for striking, and a tapered mid-section connecting
said handle portion and said barrel portion, wherein said barrel
portion is radially stiffer in the middle of the said barrel
portion and circumferentially less stiff radially in the two end
portions of the said barrel portion.
9. A bat according to claim 8 wherein said polymer composite
material comprises a resin matrix encapsulating reinforcement
fibers wherein said resin is selected from the group of resin
consisting of epoxy, vinyl ester, polyester, urethane, nylon, and
mixtures thereof and wherein said reinforcement fibers are selected
from the group consisting fiberglass, graphite, carbon, aramid,
boron, nylon and mixtures thereof.
10. A polymer composite baseball bat comprising a cylindrical
handle portion for gripping, a cylindrical tubular barrel portion
for striking, and a tapered mid-section connecting said handle and
barrel portion, wherein the radial stiffness of said barrel portion
is highest in the said barrel portion's middle area, lowest at the
ends of the said barrel portion, and generally uniformly changes
from the middle portion to each end portion of said barrel
portion.
11. A bat according to claim 10 wherein a polymer composite
material comprises a resin matrix encapsulating reinforcement
fibers wherein said resin is selected from the group of resin
consisting of epoxy, vinyl ester, polyester, urethane, nylon, and
mixtures thereof and wherein said reinforcement fibers are selected
from the group consisting fiberglass, graphite, carbon, aramid,
boron, nylon and mixtures thereof.
12. A tubular baseball bat comprising a cylindrical handle portion
for gripping, a cylindrical tubular barrel portion for striking,
and a tapered mid-section connecting said handle and barrel
portion, wherein said barrel portion's thickness varies over said
barrel portion's length.
13. A bat according to claim 12 wherein said barrel portion's
thickness is at least 5% thinner, at either or both end portions of
said barrel portion, than the central portion of said barrel
portion.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to baseball bats and more
particularly to tubular baseball bats, constructed of a variety of
materials, and more particularly to baseball bats designed to
improve player performance as defined by greater hitting distance,
and more particularly to baseball bats whose performance as defined
by hitting distance is controlled by performance standards
established by regulatory bodies.
BACKGROUND OF THE INVENTION AND PRIOR ART
[0002] Baseball and softball bats, hereinafter referred to simply
as "baseball bats" or "bats", are today typically made solely from
aluminum alloys, or aluminum alloys in combination with composite
materials (hybrid bats), or most recently solely from composite
materials (with the exception of solid wooden bats for the Major
Leagues). Such bats are tubular (hollow inside) in construction in
order to meet the weight requirements of the end user, and have a
cylindrical handle portion for gripping, a cylindrical barrel
portion for striking, and a tapered mid-section connecting the
handle and barrel portions. Such bats have constant stiffness along
their barrel portion length.
[0003] When aluminum alloys initially replaced wooden bats in most
bat categories, the original aluminum bats were formed as a single
member, that is, they were made in a unitary manner as a
single-walled aluminum tube for the handle, taper, and barrel
portions. Such bats are often called single-wall aluminum bats and
were known to improve performance relative to wooden bats as
defined by increased hit distance. More recently (in the mid
1990's), improvements in bat design largely concentrated on further
improving bat performance. This was accomplished primarily by
thinning the barrel or hitting portion of the bat frame and adding
inner or internal, and or outer or external, secondary members
extending along the entire barrel length; these members are often
referred to respectively as inserts or sleeves; while the main
member is often referred to as a body, shell or frame in the prior
art. Such bats are often called double-wall bats or multi-walled
bats in the case of more than two walls.
[0004] The prior art of such double walled and multi-walled tubular
bats generally refer to improved performance or hit distance
resulting from trampoline effect, spring, compliance, rebound,
flexibility, etc. resulting from the multi-wall two or more member
construction along the entire barrel length allowing the barrel
portion of the bat to deflect or flex more upon ball impact which
propels the ball faster and further than prior art bats. The
scientific principle governing improved bat performance is bending
theory. When a ball impacts a bat it has kinetic energy that must
be absorbed by the bat in order to stop the ball. The bat stores
this energy by flexing. After the ball is stopped, the bat returns
the energy it stored by rebounding and sending the ball back
towards where it came from. The more the bat barrel or striking
portion deforms upon ball impact without failing (denting or
breaking), the lower the energy loss in the ball, and the greater
the energy return to the ball from the bat as the tubular bat
barrel portion impacted returns to its original shape. To allow the
bat barrel portion to deform, requires lowering the radial
stiffness of the barrel portion. The prior art double walled and
multi-walled tubular bats accomplish this by thinning the main
member barrel portion and adding thin secondary member insert(s)
and/or sleeve(s) which are not joined to the main member, extend
full length of the barrel portion, and result in lowered constant
stiffness along the barrel portion.
[0005] U.S. Pat. No. 5,303,917 to Uke discloses a two member bat of
thermoplastic and composite materials.
[0006] U.S. Pat. No. 5,364,095 to Easton discloses a two member bat
consisting of an external metal tube and an internal composite
sleeve bonded to the inside of the external metal tube and running
full length of the barrel portion of the bat.
[0007] U.S. Pat. No. 6,322,463B1 to Chauvin discloses the method of
tuning a unitary member all composite bat.
[0008] U.S. Pat. No. 5,415,398 to Eggiman discloses a two member
metallic bat consisting of a frame and internal insert of constant
thickness running full length of the barrel portion of the bat in a
double-wall construction. Further, U.S. Pat. Nos. 6,251,034B1 and
6,482,114B1 disclose variations to U.S. Pat. No. 5,415,398.
Further, U.S. Pat. No. 6,251,034B1 discloses a polymer composite
second tubular member running full length of the barrel portion of
the bat with the members joined at the ends only of the barrel
portion with the balance of the composite member freely movable
relative to the primary member. U.S. Pat. Nos. 6,440,017B1 and
6,612,945 B1 to Anderson also disclose two member bats with an
outer sleeve and inner shell of constant thickness running full
length of the barrel portion..
[0009] U.S. Pat. No. 6,063,828 to Pitzenberger discloses a two
member bat consisting on an internal body and an external shell of
constant thickness running full length of the barrel portion in a
double-wall construction. U.S. Pat. No. 6,461,760B1 to Higginbotham
discloses the bat of U.S. Pat. No. 6,053,828 with a composite shell
formed to an outer shell running full length of the barrel portion
of the bat.
[0010] Similarly, U.S. Pat. No. 6,425,836B1 to Mizuno discloses a
two member bat with a lubricated coating between layers or a weak
boundary layer formed on the surfaces of the inner member.
[0011] U.S. patent Pub. 2001/0094882 A1 by Clauzin discloses a two
member bat consisting of an outer shell and an insert laminate
partially bonded to the shell.
[0012] In all prior art multi-walled tubular bats, the bat frame
primary and secondary members extend along the entire barrel length
and are of constant thickness. Also, the bat members are not
joined, except at their ends, in order to reduce radial stiffness
of the barrel portion to improve bat performance. Also, in all
cases, the radial stiffness of the barrel portion is uniform or
constant full length of the barrel portion of the bats.
[0013] While the prior art single member, and more particularly,
double-walled and multi-walled tubular bats have demonstrated
improved performance as claimed, various regulatory bodies have
raised safety concerns regarding improved performance bats and
thus, some have established maximum performance standards for
various categories of baseball bats under their jurisdiction. As a
result, manufacturers of baseball bats are required to pass various
controlled laboratory tests, such as, bbf (batted ball
performance), bbs (batted ball speed), etc. Further, for a given
bat category (eg. slowpitch softball), there may be two or more
regulatory bodies each of which may establish a different standard.
Further, any of the regulatory bodies may change their standard
from time to time. Such new or changed or varying regulations are
extremely problematic, costly, and disruptive for both
manufacturers and players.
[0014] The one solution to the problem of lowering performance of
the prior art bats in order to meet new or changed performance
standards is to increase thickness full length of one or more of
the barrel members, and/or the single wall bat frame, which
increases radial stiffness thus reducing performance. The increased
wall thickness solution of the prior art tubular bats applied along
the entire barrel length of either the main member frame and/or
secondary barrel members can increase weight such that the finished
bat weight standard or objective is exceeded and thus, the bat in
question is obsolete. This results in costly inventory write-offs
for the manufacturer while individual players must replace an
otherwise good bat with a new bat which meets the current
standards. Further, the manufacturer incurs significant redesign
and retooling costs and marketing timing issues (ie. for at least a
period of time, have no bat which meets the new standard).
[0015] Therefore, what is needed is a simple, low cost invention to
decrease bat performance of tubular bats in a controlled manner, in
order to meet lowered or changed bat performance standard
requirements without significantly increasing bat weight. Further,
what is needed is that such an invention can be employed for both
new bats being manufactured and used bats returned from players (to
be returned to players with lowered performance to meet the new or
changed standard involved). Further, what is needed is the required
performance decrease at least partially be offset by improving
another bat characteristic such as "sweetspot" (barrel portion
length of maximum bat performance) size. Also, what is needed is
newly designed tubular bats with a predetermined bat performance
with larger sweetspot areas than bats of the prior art.
SUMMARY OF THE INVENTION
[0016] Therefore, in view of the foregoing, what is needed is
tubular baseball bats with variable stiffness along their barrel
portions. A main object of the present invention is to provide
tubular baseball, and particularly existing bats, with changed
(usually decreased) bat performance, without significantly
increased weight, in order to meet new or changed performance
standards. To achieve this, the bats of the present invention are
stiffened in the barrel area of peak bat performance commonly
referred to as the sweetspot. Typically, this is an area
approximately 2" to 4" in width as compared to barrel portion
lengths of 4" to 16". This is achieved by inserting or adding to
the bat a circumferential stiffner in the region of the
sweetspot.
[0017] The preferred short light weight polymer composite
circumferential stiffener employed adds only minimal weight to a
given bat thus allowing the stiffened bat to be continued to be
used within the required weight requirements of baseball. The
stiffener of the present invention can be added to used bats
returned from players for modification to meet a changed regulation
and also can be added to bats manufactured before a regulation
change occurs, allowing such previously manufactured bats to meet a
changed standard. Though somewhat heavier, a short metallic
stiffener could also be employed. An alternative solution of the
present invention to vary stiffness, and thus bat performance,
along the barrel portion is to vary thickness along the barrel
portion.
[0018] A second object of the present invention is to provide
tubular bats with bat performance decreased to meet a given changed
regulation in a precisely controlled manner; that is, if the
standard requires a standard of x maximum and a given bat design
has a performance greater than x, then following the precisely
located stiffening, the bat performance will meet the x requirement
and not be significantly less than x. In the present invention,
this is accomplished by engineering calculations considering
selection of the composite fiber type, the fiber size, the angles
of the fibers, and the thickness of the polymer composite stiffener
to be employed to precisely lower the bat performance. Proper
engineering design of these variables of a polymer composite
results in a polymer composite stiffener which when added to a
tubular bat results in that bat precisely meeting the desired new
bat performance.
[0019] A third object of the present invention is to provide
existing tubular bats with a specific predetermined bat maximum bat
performance with a larger sweetspot than tubular bats of the prior
art. In the present invention this is accomplished by precisely
stiffening only the peak performance area (generally the sweetspot
area) of the existing bat to the performance level of the barrel
portion areas immediately adjacent on both sides of the sweetspot
of the unstiffened bat. The resultant effect is to approximately
double the sweetspot size (that is, the area of the barrel portion
which provides maximum bat performance).
[0020] A fourth object of the present invention is to provide newly
designed tubular all polymer composite baseball bats with a
predetermined bat performance with larger sweetspot areas than bats
of the prior art. In the present invention this is accomplished by
graduating the radial stiffness of the barrel portion along the
entire barrel length. Specifically, the peak performance area
(generally the sweetspot area) is designed to have the highest
radial stiffness while the area of the barrel portion nearest the
taper and barrel ends have the lowest radial stiffness and with the
barrel portion between the sweetspot and barrel ends being
graduated. The resultant effect is a sweetspot area that runs
substantially full length of the barrel portion. In the present
invention this is accomplished by engineered selection of the
composite fiber type(s), fiber sizes(s), fiber angles(s), and the
total composite multi-layered laminate or structure having
graduated radial stiffness along the barrel portion length.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The invention will now be described with reference to the
accompanying drawings, in which:
[0022] FIG. 1 shows a longitudinal cross-section of a typical prior
art single wall tubular bat with a singular frame, or member,
construction.
[0023] FIG. 1A shows a cross-sectional area take at any location
through the barrel portion of the FIG. 1 prior art tubular bat.
[0024] FIG. 2 shows a longitudinal cross-section of a typical prior
art double-wall tubular bat with two separate members, a frame or
main member with an internal insert as a secondary member in the
barrel area. Both the frame and insert run the full length of the
barrel portion and are not joined full length.
[0025] FIG. 2A shows a cross-sectional area taken at any location
through the barrel portion of the FIG. 1 prior art tubular bat.
[0026] FIG. 3 shows a longitudinal cross-section of a typical prior
art double-wall tubular bat with two separate members, a frame or
main member with an external sleeve secondary member in the barrel
portion. Both the frame and sleeve run the full length of the
barrel portion and are not joined full length.
[0027] FIG. 3A shows a cross-sectional area taken at any location
through the barrel portion of the FIG. 2 prior art tubular bat.
[0028] FIG. 4 shows a longitudinal cross-section of one embodiment
of the present invention showing a single wall tubular bat in
accordance with the present invention showing an internal stiffener
generally confined to the sweetspot area of the barrel portion and
joined to the barrel portion.
[0029] FIG. 4A shows a cross-sectional area of a barrel location
not within the sweetspot area.
[0030] FIG. 4B shows a cross-sectional area within the sweetspot
area showing the internal stiffener of the present invention.
[0031] FIG. 5 shows a longitudinal cross-section of a second
embodiment of the present invention showing a single wall tubular
bat in accordance with the present invention with an external
stiffener generally confined to the sweetspot area of the barrel
portion and joined to the barrel portion.
[0032] FIG. 5A shows a cross-sectional area at a barrel location
not within the sweetspot area.
[0033] FIG. 5B shows a cross-sectional area within the sweetspot
area showing an external stiffener of the present invention.
[0034] FIG. 6 shows a longitudinal cross-section of a third
embodiment of the present invention showing a single wall polymer
composite tubular bat in accordance with the present invention
showing a localized area of the fiber type and/or angle change
resulting in increased radial stiffness generally confined to the
sweetspot area of the barrel portion.
[0035] FIG. 6A shows a cross-sectional area at a barrel location
not within the sweetspot area.
[0036] FIG. 6B shows a cross-sectional area within the sweetspot
area showing a stiffened area of changed fiber angles and/or
type.
[0037] FIG. 7 shows a longitudinal cross-section of a fourth
embodiment of the present invention showing a double-wall tubular
bat with two separate members, a frame or main member with an
internal insert as a secondary member full length in the barrel
portion, and in accordance with the present invention, showing an
internal stiffener generally confined to the sweetspot area of the
barrel portion and joined to the barrel portion.
[0038] FIG. 7A shows a cross-sectional area at a barrel location
not within the sweetspot area.
[0039] FIG. 7B shows a cross-sectional area within the sweetspot
area showing the internal stiffener.
[0040] FIG. 8 shows a longitudinal cross-section of a fifth
embodiment of the present invention showing a double-wall tubular
bat with two separate members, a frame or main member with an
external sleeve as a secondary member full length in the barrel
portion, and in accordance with the present invention showing an
external stiffener generally confined to the sweetspot area of the
barrel portion and joined to the barrel portion.
[0041] FIG. 8A shows a cross-sectional area at a barrel location
not within the sweetspot area.
[0042] FIG. 8B shows a cross-sectional area within the sweetspot
area showing the external stiffener.
[0043] FIG. 9 shows in graphical form the typical relationship
between tubular bat performance and barrel location and sweetspot
size.
[0044] FIG. 10 shows in graphical form a typical relationship
between tubular bat performance of a bat of the present invention
with an internal stiffener, and barrel location and sweetspot
size.
DETAILED DESCRIPTION OF THE INVENTION
[0045] The present invention is directed to providing tubular
baseball bats with bat performance decreased in a controlled
manner, to meet changing regulatory standards, without
significantly increasing bat weight (FIGS. 4, 5, 6, 7 and 8).
Further, such decreased bat performance can be achieved in a simple
manner at reasonably low costs and applied to both bats being
manufactured or returned from end users. Further, such bats of the
present invention can have a larger sweetspot size.
[0046] The prior art bats are shown in FIGS. 1, 2, and 3. FIG. 1
shows a single wall tubular bat with main member 16. FIG. 2 shows a
double wall tubular bat with an insert 13, formed separately from
the main member 16, which is fitted into the entire barrel length 1
of the main member 16. FIG. 3 shows a double wall tubular bat with
a sleeve 14, formed separately from the main member 16, which is
fitted over the entire barrel length 1 of the main member 16.
[0047] Though not indicated in FIGS. 1 through 8, bats of the
present invention, as do bats of the prior art, include a
traditional knob (not shown in the drawings) at the handle portion
end 5 and a traditional end cap (not shown in the drawings) at the
barrel portion end 4, both of which can be made from a variety of
materials.
[0048] Most adult tubular baseball bats of the prior art have
maximum outside barrel portion diameter 2 either 2.625 or 2.75
inches. Depending on the taper portion geometry of the mid-section
8, and the total length of the bat, the barrel length 1 as defined
by length of constant maximum diameter 2, ranges from 4 to 12
inches. Barrel wall thickness 6 ranges from 0.100 inches to 0.140
inches for aluminum bats and up to 0.220 inches for all composite
bats.
[0049] Most youth baseball bats and softball bats of the prior art
have maximum outside barrel portion diameter 2 of 2.25 inches.
Depending on the taper portion geometry of the mid-section 8, the
barrel length 1 ranges from 4 to 16 inches. Barrel wall thickness 6
ranges from 0.060 to 0.090 inches for aluminum bats and up to 0.220
inches for all composite bats.
[0050] The bats of the present invention, shown in FIGS. 4, 5, 6, 7
and 8 have similar dimensions to the foregoing prior art bats shown
in FIGS. 1, 2 and 3.
[0051] A first embodiment of the present invention FIG. 4 is a
single wall tubular baseball bat consisting of a cylindrical handle
portion 7 for gripping, a cylindrical tubular barrel portion 9 for
striking or hitting, and a tapered mid-section 8 connecting the
handle 7 and barrel 9 portions, with a thin polymer composite
stiffener 18 located internally within the barrel portion 9 and
extending longitudinally in the sweetspot area 19 of the barrel
length 1.
[0052] A polymer composite is a non-homogenous material consisting
of continuous fibers embedded in, and wetted by, a polymeric resin
matrix whereby the properties of the material are superior to those
of its constituent fibers and resin taken separately. Such polymer
composites are anistropic materials since they exhibit different
responses to stresses applied in different directions depending on
how the fibers are aligned or angled within the matrix.
[0053] Other materials commonly used in bat constructions such as
aluminum, wood and plastics are not anistropic and are thus limited
in controlling bat performance; for example, radial stiffness is
equal to longitudinal stiffness and cannot be graduated along the
barrel length 1. However, with composite materials, which are
preferred, properties of bats made in accordance with the present
invention, such as radial stiffness which determines bat
performance can be controlled (i.e. designed to a given
requirement) by altering such parameters as the fiber alignments
along the bat length 1, and/or the type of fibers chosen, their
dernier or layout density and/or the thickness of the polymer
composite structure.
[0054] Generally, the fiber materials used are selected from a
group consisting of fiberglass, graphite or carbon, aramid, boron,
nylon, or hybrids of any of the foregoing, all of which are
commercially available. The resins used to impregnate, wet out, and
encapsulate or imbed the fiber materials are generally selected
from a group consisting of epoxy, polyester, vinyl ester, urethane,
or a thermoplastic such as nylon, or mixtures thereof.
[0055] The first embodiment FIG. 4 of the present invention
consists of a thin polymer composite stiffener 18 located
internally within the barrel portion 9 generally in the sweetspot
area 19 located in proximity to the middle area of the barrel
length 1 of a single wall tubular bat. The resultant stiffened bat
results in a predetermined calculated lower performance, with a
bigger (longer) sweetspot 19, as subsequently explained.
[0056] The sweetspot area 19 of a baseball bat is generally
referred to as that area along the barrel length 1 in which bat
performance is greatest; that is, a ball struck within the
sweetspot area 19 will travel further than a ball struck on either
side of the sweetspot area. Typically, the sweetspot area 19 is
located around the middle of the barrel length 1 and is in the
order of 2" to 4" in length as compared to barrel lengths 1 ranging
from approximately 4" to 16" or more.
[0057] In actual practice, the performance of a baseball bat of the
prior art follows a statistical normal distribution along the
barrel length 1, usually centered near the middle of the barrel
length 1 in the sweetspot area 9. FIG. 9 shows a typical bat
performance distribution example with a 12" barrel length 1.
[0058] In FIG. 9, the maximum bbs (one measure of bat performance
standard) is 100 while most players would describe the sweetspot as
being approximately 2" long (that is, the portion of the barrel
length equal to or greater than 98 bbs). The bat of this particular
sample meets a bat performance factor standard of 100 bbs maximum
if so regulated.
[0059] If the applicable regulatory body for the bat in the FIG. 9
example changed the bat performance standard from 100 bbs maximum
to say 96 bbs maximum, the bat of the present invention with a
specifically designed 4" polymer composite stiffener 18 located in
the center of the barrel length 1. FIG. 10 shows the bbs versus
barrel length for this example.
[0060] In FIG. 10, in an example of the present invention, the
polymer composite stiffener 18 is approximately twice as stiff in
the center 2" of the sweetspot area 19 as in the 1" area
immediately adjacent to the center area on each side of the center
area. The polymer composite stiffener 18 fiber type, fiber angles
and thicknesses are designed such as to reduce the bbs from 100 to
96 in the center area 2" of the barrel length 1 and from 98 to 96
bbs in the 1" areas immediately adjacent to the center area. As a
result of the present invention, the resultant typical example bat
meets the lowered regulatory standard of 96 bbs with a sweetspot
area 19 which has been increased by 100% (from 2" wide to 4"
wide).
[0061] The first embodiment (ie. internal stiffener 18) of the
present invention is particularly suited to retrofitting used bats
returned by players and making legally playable under a revised
standard.
[0062] The thin polymer composite stiffener 18 of the present
invention is typically in the order of 0.005" to 0.040" thick with
length 2" to 6" which is typically less than 50% of the barrel
length and is preferably bonded, fully or partially, to the main
member 16, or to the secondary member insert 13 of FIG. 7 or to the
secondary member sleeve 14 of FIG. 8, or combinations thereof.
Though not shown, an alternative solution (since stiffness is
proportional to thickness) to the stiffener 18 is to vary the
barrel thickness 6 along the barrel length 1, either full length or
any portion of the barrel length 1 in order to vary bat
performance.
[0063] A second embodiment of the present invention FIG. 5 is a
single wall tubular baseball bat which in accordance with the
present invention has a thin polymer composite stiffener 18 located
externally to the barrel portion 9 generally in the sweetspot area
19 located in proximity to the middle area of the barrel length 1.
The resultant stiffened bat results in a calculated lower
performance, with a bigger (longer) sweetspot 19, as previously
explained.
[0064] A third embodiment of the present invention FIG. 6 is a
single wall tubular polymer composite baseball bat which in
accordance with the present invention has a localized area of fiber
type and/or angle change 20 resulting in increased radial stiffness
generally in the sweetspot area 19 located in proximity to the
middle area of the barrel length 1. Though not shown, this
embodiment applies equally well to double-wall and multi-wall (more
than two walls) tubular all polymer composite baseball bats and is
limited to newly designed polymer composite single wall,
double-wall, and multi-walled new bats as opposed to field returned
bats. Though not shown, the fiber types, and/or fiber angles,
and/or fiber sizes, and/or composite thickness can be designed such
as to graduate the radial stiffness of the barrel portion 1 along
its entire length. That is, the radial stiffness could be highest
in the peak performance area (generally the sweetspot area 19) and
gradually changing in uniform increments towards the barrel ends
where the radial stiffness would be lowest. The resultant effect is
a sweetspot area 19 that extends substantially full length of the
barrel portion 1.
[0065] A fourth embodiment of the present invention FIG. 7 is a
double-wall tubular bat showing two separate members, a frame or
main member 16 with an internal insert 13 as a secondary member
full length in the barrel length 1, and in accordance with the
present invention has a stiffener 18 located internally within the
insert 13 generally confined to the sweetspot area 19, along the
barrel length 1. Though not shown, the stiffener 18 could be
located externally to the main member 16 or between the main member
16 and the internal insert 13. Also, though not shown, in
multi-walled bats the stiffener 18 could be located internally, or
externally, or between the members, or combinations thereof.
[0066] A fifth embodiment of the present invention FIG. 8 is a
double-wall tubular bat showing two separate members, a frame or
main member 16 with an external sleeve 14 as a secondary member
full length in the barrel length 1, and in accordance with the
present invention has a stiffener 18, located externally to the
sleeve 14, generally confined to the sweetspot area 19, along the
barrel length 1. Though not shown, the stiffener 18 could be
located internally to the main member 16 and the external sleeve
14. Also, though not showm, in multi-walled bats, the stiffener 18
could be located internally, or externally, or between the members,
or combinations thereof.
[0067] The invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The present embodiments are therefore to be considered as
illustrative and not restrictive, the scope of the invention being
indicated by the appended claims rather than by the foregoing
description, and all changes that come within the meaning and range
of equivalency of the claims are therefore intended to be embraced
therein.
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