U.S. patent application number 10/844476 was filed with the patent office on 2004-10-21 for composite softball bat with inner sleeve.
This patent application is currently assigned to Miken Composites, LLC.. Invention is credited to Griffith, George B., Vacek, Matthew.
Application Number | 20040209716 10/844476 |
Document ID | / |
Family ID | 46301295 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040209716 |
Kind Code |
A1 |
Vacek, Matthew ; et
al. |
October 21, 2004 |
Composite softball bat with inner sleeve
Abstract
A softball bat is made substantially out of composite material.
The main portion of the bat includes a substantially tubular
hitting surface, a taper, and a handle. A plurality of sleeves are
added within the hitting surface to form a flexible bat.
Inventors: |
Vacek, Matthew; (Melrose,
WI) ; Griffith, George B.; (Caledonia, MN) |
Correspondence
Address: |
Schwegman, Lundberg, Woessner & Kluth, P.A.
P.O. Box 2938
Minneapolis
MN
55402
US
|
Assignee: |
Miken Composites, LLC.
|
Family ID: |
46301295 |
Appl. No.: |
10/844476 |
Filed: |
May 12, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10844476 |
May 12, 2004 |
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10438196 |
May 14, 2003 |
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10438196 |
May 14, 2003 |
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09883790 |
Jun 18, 2001 |
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60263020 |
Jan 19, 2001 |
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Current U.S.
Class: |
473/567 |
Current CPC
Class: |
A63B 59/54 20151001;
A63B 59/50 20151001; A63B 2102/18 20151001; A63B 2209/02
20130101 |
Class at
Publication: |
473/567 |
International
Class: |
A63B 059/06 |
Claims
What is claimed is:
1. A bat comprising: a hitting surface; a handle element attached
to the hitting surface; a first sleeve positioned within the
hitting surface; and a second sleeve positioned within the hitting
surface, wherein the hitting surface.
2. The bat of claim 1 wherein the first sleeve and the second
sleeve are comprised of composite materials.
3. The bat of claim 2 wherein the hitting surface has a first
stiffness and one of the first sleeve and the second sleeve
positioned within the hitting surface has a second stiffness
different than the first stiffness.
4. The bat of claim 2 wherein the hitting surface is made from a
first set of fibers and a first resin and wherein the first sleeve
and second sleeve are made from a second set of fibers and a second
resin, the second set of fibers and the second resin being
different than the first set of fibers and first resin.
5. The bat of claim 4 wherein the second fiber and resin is
impregnated in the second set of fibers.
6. The bat of claim 4 wherein the second set of fibers and resin is
a sheet of material.
7. The bat of claim 1 wherein the second sleeve is formed on the
first sleeve.
8. The bat of claim 1 wherein the first sleeve is separated from
the first sleeve by a layer of material.
9. The bat of claim 2 wherein the first sleeve is separated from
the second sleeve by a layer of a release material.
10. A bat comprising: a hitting surface further including; a first
wall; a second wall; and a third wall; and a handle element
attached to the hitting surface.
11. The bat of claim 10 wherein the hitting surface is in the shape
of a barrel.
12. The bat of claim 10 wherein the first wall is made of a first
material and the second wall is made of a second material.
13. The bat of claim 12 wherein the first material is metal.
14. The bat of claim 12 wherein the first material is a composite
material.
15. The bat of claim 10 wherein the second wall and the third wall
are made of the same materials.
16. The bat of claim 10 wherein the second wall and the third wall
are made of different materials.
17. The bat of claim 10 wherein the bat has a flexibility of
greater than 600.
18. A bat comprising: a hitting surface having a flexibility within
the range of 600 to 1300; and a handle attached to the hitting
surface.
19. The bat of claim 18 wherein the flexibility is within the range
of 800 to 1200.
20. The bat of claim 18 wherein the flexibility is within the range
of 950 to 1150.
21. A method of forming a bat having a handle and a hitting
surface, the method comprising: forming a first sleeve; forming a
second sleeve; and fitting the first sleeve and the second sleeve
within the hitting surface.
22. The method of claim 21 wherein the first sleeve is formed of
metal.
23. The method of claim 21 wherein the first sleeve and the second
sleeve are formed of metal.
24. The method of claim 21 wherein the first sleeve is formed of a
composite material.
25. The method of claim 21 wherein the first sleeve and the second
sleeve are formed of a composite material.
26. The method of claim 21 wherein the step of forming a first
sleeve and a forming a second sleeve further comprises: laying up a
first plurality of layers of material; covering the first plurality
of layers of material with a release material; and laying up a
second plurality of layers of material.
27. The method of claim 26 wherein covering the first plurality of
layers with a release material includes covering the first
plurality of layers with polypropylene.
28. The method of claim 25 wherein forming a first sleeve includes
wrapping a plurality of layers about a mandrel and wherein, forming
a second sleeve includes wrapping a plurality of layers about a
mandrel.
29. The method of claim 21 further comprising: loading a portion of
the bat; and measuring the amount of deflection.
30. The method of claim 29 wherein loading a portion of the bat
includes placing a force on the hitting surface of the bat.
31. The method of claim 29 wherein loading a portion of the bat
includes placing a force on the surface of the bat having a first
sleeve and a second sleeve.
32. The method of claim 29 wherein loading a portion of the bat
includes placing a force on a plurality of areas associated with
the hitting surface of the bat.
33. The method of claim 32 wherein measuring the amount of
deflection includes measuring the deflection at the plurality of
areas associated with the hitting surface of the bat.
34. The method of claim 32 wherein measuring the amount of
deflection includes measuring the deflection at the plurality of
areas associated with the hitting surface of the bat, the method
further comprising averaging the amount of deflection for each of
the measured areas.
35. The method of claim 34 wherein loading the hitting surface at
the plurality of areas includes placing substantially the same load
on each of the plurality of areas of the hitting surface.
36. The method of claim 32 further comprising dividing the load
placed on the bat by the measured deflection to yield a number
representing flexibility of the bat.
37. The method of claim 32 further comprising: dividing the load
placed on the bat by the measured deflection to yield a number
representing flexibility of the bat; determining a number
representing flexibility at a plurality of points on the bat; and
averaging the determined flexibility numbers.
38. The method of claim 37 wherein the flexibility numbers are
determined for a hitting surface of the bat.
39. The method of claim 37 wherein the load placed on the bat is
substantially equal at the various portions of the bat.
40. A method of forming a bat having a handle and a hitting
surface, the method comprising: forming a hitting surface; and
forming a plurality of sleeves adjacent the hitting surface.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/438,196 filed May 14, 2003, which is a
continuation-in-part application of U.S. patent application Ser.
No. 09/883,790 filed on Jun. 18, 2001, which claims priority under
35 U.S.C. 119(e) from U.S. Provisional Application Ser. No.
60/263,020 filed Jan. 19, 2001, which applications are incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of bats and more
particularly to a softball bat.
BACKGROUND OF THE INVENTION
[0003] For many years softball bats were made of wood. Traditional
athletic bats comprised of wood are expensive and consume valuable
natural resources. A disadvantage of wood bats is that they
frequently break during use. A further disadvantage of wood bats is
that they are exceedingly difficult to design for consistent
performance, given the inconsistency of the natural material. In
addition, wooden bats are made of ash or very hard pine. The
sources of such woods are becoming increasingly scarce.
[0004] In the past fifteen or twenty years, softball bats made of
metal were introduced. Metal bats, although more durable than wood
bats, also have problems. One of the many problems associated with
a metal bat is that the material is fixed and, as a result, so are
the parameters of the material. Metal bats have a fixed density and
a given weight. As a result, the engineering parameters that can be
varied can only be varied within a limited range.
[0005] Currently, metal softball bats are more commonly used than
wooden softball bats. A common structure in various non-wooden
softball bats includes a hollow bat made with a handle and a
hitting surface. The hitting surface includes a tubular portion and
a sleeve fit inside the tubular portion. The sleeve is also made of
metal. The metal bat and sleeve construction has problems. Several
of the problems associated with metal softball bats having metal
sleeves stems from the impact or large shock load exerted on the
metal bat as a result of hitting the softball. The shock loading
produces extremely large forces between the bat and the ball. The
result is that the metal bat dents when a ball is hit. In other
words, the metal may dent in some form when the ball is hit. Some
dents are small and some dents are large. Regardless of the size of
the dent, energy is lost every hit since some of the energy is used
to dent the metal rather than transferred to the softball. The
dents also result in a less durable bat. Once dented, each
subsequent hit is a further cold working of the metal. In some
instances, a microscopic crack can also be formed as the result of
denting of the bat. The crack will get bigger and bigger until the
amount of material left fails due to shock loading. Many bats fail
quickly. Some bats may fail after as few as twenty-five hits.
[0006] More recently, composite bats have been introduced.
Composite bats include a reinforced plastic with a metal portion.
For example, U.S. Pat. No. 4,546,976 which issued to T. N. Jones on
Oct. 15, 1985, discloses a reinforced plastic bat with a separate
handle section that is softer than the hitting section. Another
example is U.S. Pat. No. 4,569,521 which issued to A. W. Mueller on
Feb. 11, 1986, which discloses a composite bat having a tapered
aluminum spar encased in polyurethane foam in order to provide
stiffness and freedom from excessive vibrations. Currently,
composite bats have composite shells and metal inner sleeves in the
hitting portion of the bat. These bats have some of the same
problems as a metal bat. In a composite bat, the metal sleeves dent
over time and the impact energy that should be transferred to the
ball is absorbed by denting the metal sleeve.
[0007] U.S. Pat. No. 5,722,908 issued to Feeney et al. on Mar. 3,
1998, discloses a composite bat with a metal barrel, and a method
of fabricating same. The bat has a frame having a recess and
fabricated of a composite material of fibers in a matrix binder. A
metal sleeve is inserted over the recess of the frame, which forms
a hitting surface.
[0008] What is needed is a more durable softball bat. What is also
needed is a bat which will not dent so that more energy is
transmitted or applied to the softball. Another way of looking at
this is that what is needed is a bat which will not dent so that
little or no energy is wasted denting the bat. Also needed is a bat
which will not dent or be cold worked such that an inherent weak
spot is formed.
SUMMARY OF THE INVENTION
[0009] A softball bat is made entirely out of composite material.
The main portion of the bat includes a substantially tubular
hitting surface and a handle. A composite sleeve is added within
the hitting surface. The sleeve is made of composite material. The
hitting surface is also made of composite material.
[0010] Advantageously, the composite material has a lower density
than metals used to make bats, such as aluminum or titanium. As a
result, more material can be used resulting in a more durable bat
for a given weight of bat. The composites also have a higher
strength than aluminum and titanium and their alloys. Therefore, a
stronger bat can be produced. In addition, the composite does not
dent and therefore more energy is transferred to the ball. There is
less, if any, energy wasted on denting the bat or the inner sleeve.
Therefore, the inventive bat hits farther than a wooden or metal
bat or bat having metal parts. The inventive bat is made entirely
of composite material. Composite material can be made either more
stiff or more flexible than a metal bat. The design parameters of a
composite are more flexible so that either a more flexible or
stiffer bat can be formed by varying the engineering parameters.
The additional flexibility in using composite material allows
designers to form bats with selected performance characteristics.
If the bat is made to be more flexible, the inventive bat has a
durability advantage since the bat does not dent and begin the
somewhat slow process of failing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of a ball bat, with a portion
of the tubular hitting surface broken away to show a sleeve
according to the present invention.
[0012] FIG. 2 is a longitudinal sectional view of the ball bat of
the present invention with the end cap exploded away and showing
the composite inner sleeve.
[0013] FIG. 3A is an enlarged cross section view of the present
invention drawn along lines 3A-3A of FIG. 2.
[0014] FIG. 3B is an enlarged cross section view along line 3B-3B
in FIG. 2.
[0015] FIG. 3C is an enlarged cross section view along line 3C-3C
in FIG. 2.
[0016] FIG. 4A is a plan view of the two initial fiber socks of the
bat.
[0017] FIG. 4B is a plan view of the shortened fiber sock placed
over the initial sock layers shown in FIG. 4A.
[0018] FIG. 4C is a plan view of the fiber socks of the bat shown
in FIG. 4B with an added hoop wrap at the tapered portion of the
bat.
[0019] FIG. 4D is a plan view of the fiber socks of FIG. 4C after
being covered by another sock.
[0020] FIG. 4E is a plan view of the fiber socks of the bat shown
in FIGS. 4A-4D with a hoop wrap added to the handle and part of the
tapered portion of the bat.
[0021] FIG. 5 is an exploded perspective view of a set of sheets
pre-impregnated fibers and a mandrel used to form the inner sleeve
of the present invention.
[0022] FIG. 6 is a plan view of the fiber layers on the mandrel
being wrapped with a layer of tape.
[0023] FIG. 7 is a cross sectional view of the mandrel with a set
of sheets and three layers of tape wrapped around the mandrel.
[0024] FIG. 8 is a perspective cutaway view of the fiber layers in
the sleeve.
[0025] FIG. 9 is a longitudinal sectional view of another
embodiment of the ball bat of the present invention with the end
cap exploded away and showing the composite inner sleeve.
[0026] FIG. 10 is an enlarged cross section view along line 10-10
in FIG. 9.
[0027] FIG. 11 is an exploded perspective view of a set of sheets
pre-impregnated fibers and a mandrel used to form the inner sleeve
of the present invention.
[0028] FIG. 12 is a plan view of the fiber layers on the mandrel
being wrapped with a layer of tape.
[0029] FIG. 13 is a cross sectional view of the mandrel with a set
of sheets and three layers of tape wrapped around the mandrel.
[0030] FIG. 14 is a perspective cutaway view of the fiber layers in
the sleeve.
[0031] FIG. 15 is a perspective view of a set of sheets wrapped
about a mandrel used to form a bat according to another embodiment
of the invention.
[0032] FIG. 16 is a top view of a sheet of layup material used in
one embodiment of a bat.
[0033] FIG. 17 is a top view of a mandrel like the one shown in
FIG. 15 within a mold for a bat.
[0034] FIG. 18 is a schematic view of one embodiment of a fixture
for measuring the flexibility of a bat.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0035] In the following detailed description of the preferred
embodiments, reference is made to the accompanying drawings, which
form a part hereof, and in which are shown by way of illustration
specific embodiments in which the invention may be practiced. It is
to be understood that other embodiments may be utilized and
structural changes may be made without departing from the scope of
the present invention.
[0036] The invention described in this application is useful with
all mechanical configurations of bats including softball bats and
baseball bats. FIG. 1 is an exploded view of one type of a bat 100
having a substantially tubular hitting surface 110 and a handle
120. The ball bat 100 is made of composite material. The main
portion of the bat 100 includes a substantially tubular hitting
surface 110. A handle 120 is attached to the hitting surface. The
handle 120 and barrel are integral in the bat shown in FIG. 1. It
should be noted that the bat could be formed of a separate handle
120 and tubular hitting surface or barrel 110. The tubular hitting
surface 110 and the attached handle 120 form the body 140 of the
bat. The diameter of the handle 120 is less than the diameter of
the tubular hitting surface 110 and therefore the body 140 of the
bat includes a tapered portion 114 which is positioned between the
handle 120 and the tubular hitting surface 110. A composite sleeve
112 is added within the body 140 of the bat and more specifically
within the tubular hitting surface 110.
[0037] The sleeve 112 of the bat 100 is also made of composite
material. Therefore, both the hitting surface 110 and the sleeve
112 are made of composite material. The inner sleeve 112 fits
inside the hitting surface 110 of the bat 100. The inner sleeve 112
is made of a composite material which includes a fiber and a resin.
The fibers can be made of Kevlar, graphite, carbon, boron, rayon,
nylon, fiberglass, other plastics or other polymer materials.
Graphite nano tubes may also be used. The resin or binding material
may include thermosetting resin systems, epoxies, ceramics, or
thermoplastics. The fibers are impregnated with a resin to form a
composite material. A plug 130 is molded to the free end of the
hitting surface 110. The plug 130 is typically molded into the free
end of the bat 100 using a separate process.
[0038] FIG. 2 shows the bat 100 assembled and partially cut away
along the length of the bat 100. The sleeve 112 is positioned
within the substantially tubular hitting surface 110. In other
words, the barrel of the bat is hollow. In the embodiment shown,
the sleeve 112 is placed so that it tightly fits within the barrel
or tubular batting surface 110. The plug 130 is also molded into
the free end of the bat 100. The bat 100 is formed and made
according to a resin transfer molding process.
[0039] The body 140 of the bat 100 is comprised of a continuous
resin matrix reinforced with a plurality of
circumferentially-extending fiber socks 324, 326, shown in FIGS.
3A, 3B, 3C and 4 and two hoops 340, 342. In the preferred
embodiment, the resin components consist of Epic S7311 part A and
part B available from Epic Resins of Omera, Wis., although other
resin components may be used in alternative embodiments. Also, in
the preferred embodiment the fiber socks 324, 326 are cross woven
and are comprised of 74% glass fiber and 26% carbon fiber, by
weight. Of course, other types of weaves and other fibers may be
used in alternative embodiments.
[0040] This particular combination of resin components and fiber
socks 324, 326 results in a high-strength yet flexible body 140.
When a ball impacts the bat 100 during the batter's swing, the bat
undergoes a localized deformation conforming to the contact area of
the ball, as well as radial or hoop deformation (i.e., the
cylindrical bat temporarily deforms into an oval when viewed in
cross section). This deformation provides a springboard or
trampoline effect which further enhances the hitting zone of the
bat 100 and provides maximum velocity to the ball when hit by the
bat. The trampoline effect provides distance to a particular
hit.
[0041] In the preferred embodiment, three fiber socks 324 a fiber
sock 326 and two hoop wraps 340, 342 are used to form the body 140
of the bat 100. The fiber socks 324 are concentrically arranged
within the resin matrix of the body 140. FIGS. 4A to 4E illustrate
the various layers of the bat as the bat is built up. As shown in
FIG. 4A, initially two fiber socks 324 are placed on a mandrel. The
two fiber socks 324 cover the body of the bat. As shown in FIG. 4B,
a sock 326 is placed over the handle 120 and a portion of the
tapered portion of the body of the bat. The next step, shown in
FIG. 4C, is a hoop wrap 340 around the tapered portion of the bat
and specifically around the two socks 324 and shortened sock 326. A
first hoop wrap 340 is done with carbon fiber wrap which is
advanced {fraction (3/32)} inches per wrap. The first hoop wrap 340
covers the tapered portion of the body 140 of the bat. The hoop
wrap 340 reduces the bulk of the socks 324, 326 and provides added
strength to the tapered portion of the finished bat. The hoop wrap
340 is done with carbon fiber wrap which is advanced {fraction
(3/32)} inches per wrap. As shown in FIG. 4D, after the initial
hoop wrap 340, another fiber sock 324 is placed over the body 140
of the bat. As shown in FIG. 4E, a second hoop wrap 342 is then
placed over the bat and overlaps a portion of the first hoop wrap
340. The second hoop wrap 342 is done over the handle 120 of the
bat and adds strength to the finished bat. The second hoop wrap 342
over the handle 120 removes bulk from the three socks 324 and the
sock 326. The hoop wrap 342 is done with carbon fiber wrap and
advanced {fraction (3/32)} of an inch per wrap. The three socks 324
substantially extend the entire length of the body 140 of the bat
100, while the sock 326 substantially extends the length of the
handle 120 and through a portion of the taper. The tubular hitting
surface 110 is also referred to as a barrel. It should be noted the
number of socks can be increased or decreased depending on the
design parameters.
[0042] In other words, the handle 120 and the tapered area between
the barrel 110 and handle 120 are hoop wrapped about the periphery
of those surfaces.
[0043] Once the fiber socks 324, 326 are placed on the mandrel and
hoop wrap 340, 342 as discussed above, and the mandrel as wrapped,
is placed into a mold where resin is injected into the mold. The
mold is placed in a press.
[0044] After curing, the mandrel and bat is removed from the mold.
The bat is cut to length. The sleeve 112 is then force fit within
the barrel or hitting surface 110 of the bat.
[0045] Since the sleeve 112 is made of a composite, the sleeve also
provides a trampolining effect in addition to the trampolining
effect of the tubular hitting surface 110 of the bat 100. The
sleeve 112 is formed of a composite which is more stiff than the
composite forming the tubular hitting surface 110 of the bat 100.
Like the tubular hitting surface 110, the deformation of the sleeve
112 conforms to the contact area of the ball. The deformation of
the sleeve 112 results in radial or hoop deformation where the
sleeve 112 temporarily deforms into an oval, when viewed in cross
section. Deformation of the sleeve 112 provides an additional
springboard or trampoline effect which is in addition to the
springboard or trampoline effect associated with the tubular
hitting surface 110 of the bat 100. The trampolining effect of the
sleeve 112 further enhances the hitting zone of the bat 100 and
provides additional velocity to the ball when hit by the bat 100.
The trampoline effect provides distance to a particular hit.
[0046] The inner sleeve 112 placed inside the barrel or tubular
hitting surface 110 of the bat 100 is made out of a different
materials than those used in the body 140. The sleeve 112 includes
sheets of inline impregnated fibers also called pre-impregnated
(some referred to as pre-preg) material. A series of sheets 500 are
laid up to form the layers of the inner sleeve 112. The inner
sleeve 112 is substantially cylindrically shaped.
[0047] As shown in FIG. 5, the sleeve 112 is formed by placing the
series of four sheets 500 on a cylindrical mandrel 520. There are
four layers of lay up which form the series of sheets 500. Two of
the layers 501, 502 are at plus or minus 45 degrees. The layer 503
is at 90 degrees and the last layer 504 is at 0 degrees. The fibers
within the impregnated or pre-impregnated material are at 0 degrees
when they are substantially aligned with a longitudinal axis 522 of
the mandrel 520 or a longitudinal axis of the cylinder of the
sleeve 112. The fibers within the impregnated or pre-impregnated
material may also be said to be at 0 degrees when they are
substantially aligned with an axis of the bat 100 running from the
center of the tubular end 110 to the center of the handle end 120.
The four layers 501, 502, 503, 504 are E-glass fiber impregnated
with resin. It should be noted that the sheets 501, 502, 503, 504
can also be any fiber and resin system. It should be noted that the
layup angles can change as well as the number of layers and still
be within the scope of the invention. For example, in some
embodiments layers 501 and 502 may be included in a single
sheet.
[0048] After the four sheets of pre-impregnated material are placed
onto the mandrel, three layers of tape are placed on the four
layers of pre-impregnated material as shown in FIGS. 6 and 7. The
three layers of tape keep the four layers of pre-impregnated
material 501, 502, 503, 504 tight, to remove voids and remove air
pockets. The first layer 601 of tape is a polypropylene tape that
is put on with a lead, with a force on the leading edge of
approximately 12 to 13 pounds. The first layer 601 of tape is 5/8"
wide. The first layer 601 of tape is wound over the four layers of
pre-impregnated material with {fraction (3/64)}" of feed and
{fraction (37/64)}" overlap. The first layer 601 of tape is
actually put on in order to provide a release layer for the sleeve
112. The first layer 601 of polypropylene tape is available from
any composite material suppliers.
[0049] After the first layer 601 of tape is placed on the mandrel,
a second layer 602 and a third layer 603 of nylon tape are then
placed on the mandrel over the first layer 601. The second layer
602 and third layer 603 are nylon tape which provides more pressure
which in turn makes a stronger part. The second layer 602 and third
layer 603 of nylon tape are available from any composite material
suppliers. The second layer 602 and the third layer 603 are each
wound onto the previous layer of tape in a similar way as the first
layer 601. The second layer 602 and the third layer 603 are wound
over the four layers of pre-impregnated material and the first
layer 601 with {fraction (37/64)}" of an overlap. The second layer
602 and the third layer 603 nylon tapes are also 5/8" wide. The
force on the leading edge of the tape is increased for the second
layer 602 and the third layer 603 to 15 pounds of lead pressure or
pressure on the leading edge. These second layer 602 wrap and the
third layer 603 wrap provide strength to the backing and removes
any voids and any air pockets that might weaken the sleeve 112 as
formed. The second layer 602 and the third layer 603 generally
strengthens the bat sleeve 112.
[0050] The arrangement on the mandrel 520, including the layers
501, 502, 503, 504 of pre-impregnated material is then placed into
an oven where it is cured for approximately three hours to ensure
that the final product is cured. It is recommended that the curing
take place for an hour on the pre-impregnated fibers, but curing is
done for three hours just to make sure that the sleeve 112 is fully
cured. After curing, the sleeve 112 is removed from the mandrel
520. The tape 601, 602, 603 is then removed by merely cutting it
off with a utility knife. The first layer 601 polypropylene tape on
the inside of course provides a release agent so the layers 601,
602, 603 release very easily from the sleeve.
[0051] FIG. 8 is a perspective cutaway view of the fiber layers in
the sleeve. The perspective cutaway view of the sleeve 112 shows
the various directions of the individual layers 501, 502, 503 and
504 within the cured sleeve 112.
[0052] The next step is to grind off enough of the exterior of the
sleeve 112 so that it can be force fit within the barrel or the
tubular hitting portion 110 of the bat 100. Even though the sleeve
112 is force fit within tubular hitting portion 110 of the bat 100,
the outer skin or tubular hitting surface 110 is able to flex and
bend and elastically deform and act like a springboard or
trampoline for the ball. The sleeve 112 also provides a
trampolining effect. In addition, the sleeve 112 provides strength
and endurance for the shock loading associated with hitting the
ball. The sleeve 112 helps launch the ball. Others may describe the
bat 100 as having the capability of giving the ball "pop" upon a
hit.
[0053] It should be noted that there are many different ways to
configure the fibers within the body 140 and within the sleeve 112.
One idea is to configure the fibers within the body 140 and within
the sleeve 112 so that the vibrational nodes associated with
hitting a ball with the bat are away from the handle 120 of the
bat. In other words, the fibers within the body 140 and within the
sleeve 112 may be changed to tune the bat 100 so that when a user
hits the softball at various positions on the tubular hitting
surface 110, the vibrational nodes would not be in the handle 120
of the bat. If the vibrational nodes can be moved from the handle
120, then there would be little or no "sting" or the vibration
transmitted to the user's hands.
[0054] Of course, different lay-ups of materials can be used in
forming the sleeve 112. Furthermore, different types of materials
can be used in forming the body 140. Changing materials or the
angles of the fibers within the bat and sleeve are considered
within the invention. Changing the shape of the bat 100 or using a
different backing for the sleeve have also been contemplated.
[0055] It should also be noted that the body 140 of the bat 100
could be made with a composite barrel or hitting surface 110 and
the handle 120 and taper could be made of another material such as
metal. A sleeve 112 could then be placed within the barrel or
hitting surface 110 and this would still be within the scope of
this invention. Although the preferred embodiment describes the
entire body 140 of the bat 100 made of composite, it is
contemplated that the tapered portion of the body 140 and the
handle 120 of other material could be substituted and be within the
scope of this invention where the hitting surface 100 of composite
includes a composite sleeve 112.
[0056] Another bat 900 will now be discussed with respect to FIGS.
9-13. There are several differences between the bat 900 and the bat
100 previously described. One of the differences is that there are
multiple sleeves within the bat. In other words, multiple sleeves
replace the single sleeve shown in FIGS. 1-8. As shown in FIGS. 9
and 10, there are a plurality of sleeves 1050, 1060 placed within
the tubular hitting surface 324 of the bat 900. The plurality of
sleeves 1050, 1060 have a combined wall thickness substantially the
same as the wall thickness of the single sleeve 112 shown in FIGS.
1-8. The plurality of sleeves 1050, 1060 are more flexible than a
single solid sleeve. An analogy can be drawn to a phone book. A
phone book with its multiplicity of pages is more flexible than a
solid block of wood. Similarly, a number of sleeves 1050, 1060 is
more flexible than a single solid sleeve. It should be noted that
although only two sleeves 1050, 1060 are shown in FIGS. 9-10, it is
contemplated that additional sleeves could be used and this is
within the scope of the invention. The flexibility afforded by
multiple layers is balanced with the required strength to determine
an appropriate number of layers.
[0057] As shown in FIG. 11, the sleeves 1050, 1060 are formed by
placing the series of five sheets 1101, 1102, 1103, 1104, 1105 on a
cylindrical mandrel 1020. Two layers of lay up 1101, 1102 form the
first sleeve 1050 and two layers of lay up 1104, 1105 form the
second sleeve 1060. A release layer 1103 is positioned between the
first sleeve 1050 and the second sleeve 1060. The release layer
1103 between the first sleeve 1050 and the second sleeve 1060 is
made of polypropylene or another suitable release material. The
release layer 1103 is a sheet of polypropylene or release material
that is placed between sheets 1102 and 1104 in the lay up. The
layer of polypropylene provides for a more flexible bat and more
specifically a more flexible hitting surface. The layers 1101, 1102
of sleeve 1060 are at plus or minus 30 degrees. The layers 1104,
1105 of sleeve 1050 are also at plus or minus 30 degrees. The
fibers within the impregnated or pre-impregnated material are at 0
degrees when they are substantially aligned with a longitudinal
axis 1022 of the mandrel 1020 or a longitudinal axis of the
cylinder of either the sleeve 1050 or the sleeve 1060. The fibers
within the impregnated or pre-impregnated material may also be said
to be at 0 degrees when they are substantially aligned with an axis
of the bat 100 running from the center of the tubular end 110 to
the center of the handle end 120. The four layers 1101, 1102, 1104,
1105 are carbon fiber impregnated with resin. It should be noted
that the sheets 1101, 1102, 1104, 1105 can also be any fiber and
resin system. It should be noted that the layup angles can change
as well as the number of layers and still be within the scope of
the invention. For example, in some embodiments, two layers may be
included as a single sheet.
[0058] After the four sheets of pre-impregnated material 1101,
1102, 1104, 1105 and the layer of release material 1103 are placed
onto the mandrel, three layers of tape are placed on the five
layers as shown in FIGS. 12 and 13. The three layers of tape keep
the four layers of pre-impregnated material 1101, 1102, 1104, 1105
and the layer of release material 1103 tight and removes voids and
air pockets from the lay up. The first layer 1201 of tape is a
polypropylene tape that is put on with a force on the leading edge
of approximately 7.5 pounds. The first layer 1201 of tape is 5/8"
wide. The first layer 1201 of tape is wound over the five layers
1101, 1102, 1103, 1104, 1105 of material with {fraction (3/64)}" of
feed and {fraction (37/64)}" overlap. The first layer 1201 of tape
is actually put on in order to provide a release layer for the
first sleeve 1050. The first layer 1201 of polypropylene tape is
available from any composite material suppliers. Of course, it
should be remembered that the amount of tension may be changed
based on material and thickness of the material used to form the
bat.
[0059] After the first layer 1201 of tape is placed on the mandrel,
a second layer 1202 and a third layer 1203 of nylon tape are then
placed on the mandrel over the first layer 1201. The second layer
1202 and third layer 1203 are nylon tape which provides more
pressure which in turn makes a stronger part. The second layer 1202
and third layer 1203 of nylon tape are available from any composite
material suppliers. The second layer 1202 and the third layer 1203
are each wound onto the previous layer of tape in a similar way as
the first layer 1201. The second layer 1202 and the third layer
1203 are wound over the four layers of pre-impregnated material and
layer of release material 1101, 1102, 1103, 1104, 1105, and the
first layer 1201 with {fraction (37/64)}" of an overlap. The second
layer 1202 and the third layer 1203 nylon tapes are also 5/8" wide.
The force on the leading edge of the tape is increased for the
second layer 1202 and the third layer 1203 to 15 pounds of lead
pressure or pressure on the leading edge. The second layer 1202
wrap and the third layer 1203 wrap provide strength to the backing
and remove any voids and any air pockets that might weaken the
sleeves 1050, 1060 as formed. The second layer 1202 and the third
layer 1203 generally strengthen the bat sleeves 1050, 1060.
[0060] The arrangement on the mandrel 1020, including the layers
1101, 1102, 1104, 1105 of pre-impregnated material and the release
layer 1103 is then placed into an oven where it is cured for
approximately three hours to ensure that the final product is
cured. It is recommended that the curing take place for an hour on
the pre-impregnated fibers, but curing is done for three hours just
to make sure that the sleeves 1050, 1060 are fully cured. After
curing, the sleeves 1050, 1060 are removed from the mandrel 1020.
The tape 1201, 1202, 1203 is then removed by merely cutting it off
with a utility knife. The first layer 1201 polypropylene tape on
the inside of course provides a release agent so that all layers
1201, 1202, 1203 release very easily from the second sleeve
1060.
[0061] FIG. 14 is a perspective cutaway view of the fiber layers in
the sleeve. The perspective cutaway view of the sleeves 1050, 1060
shows the various directions of the individual layers 1101, 1102,
1104 and 1105 within the cured sleeves 1050, 1060.
[0062] The next step is to grind off enough of the exterior of the
sleeves 1050, 1060 so that it can be force fit within the barrel or
the tubular hitting portion of the bat 900. Even though the sleeves
1050, 1060 are force fit within the tubular hitting portion of the
bat 900, the outer skin or tubular hitting surface is able to flex
and bend and elastically deform and act like a springboard or
trampoline for the ball. The sleeves 1050, 1060 also provide a
trampolining effect. In addition, the sleeves 1050, 1060 provide
strength and endurance for the shock loading associated with
hitting the ball. The flexibility of the sleeves 1050, 1060
launches the ball. Others may describe the bat 900 as having the
capability of giving the ball "pop" upon a hit.
[0063] Of course, different lay-ups of materials can be used in
forming the sleeves 1050, 1060. Also, more than two sleeves can be
made for fitting within the hitting surface of the bat 900.
Furthermore, different types of materials can be used in forming
the body 140 of the bat 900. Changing materials or the angles of
the fibers within the bat and sleeves are considered to be within
the scope of this invention.
[0064] It should also be noted that the body 140 of the bat 900
could be made with a composite barrel or hitting surface 110 and
the handle 120 and taper could be made of another material such as
metal. Sleeves 1050, 1060 could then be placed within the barrel or
hitting surface 110 and this would still be within the scope of
this invention. Although the preferred embodiment describes the
entire body 140 of the bat 900 made of composite, it is
contemplated that the tapered portion of the body 140 and the
handle 120 of other material could be substituted and be within the
scope of this invention where the hitting surface 100 of composite
includes a composite sleeve 112.
[0065] FIG. 15 is a perspective view of a set of sheets of
pre-impregnated fibers positioned on a mandrel used to form a bat.
In FIG. 15, the mandrel 1520 has a center line 1522. The mandrel
1520 is elongated and has a length approximately equal to the
barrel or substantially tubular hitting surface 110. In this
particular embodiment of the bat, longer sheets of prepreg material
are used to form the barrel of the bat right onto the mandrel 1520.
The mandrel 1522 with the layers of prepreg material and layers of
polypropylene is then placed directly into a mold 1700 and injected
with an appropriate resin material to form the bat. The mold 1700
is shown in FIG. 17. After the bat is formed, it is removed from
the mold 1700 and then the mandrel 1520 is removed from the bat as
formed so that a separate set of sleeves or a separate sleeve is
not formed and then placed into the barrel of the bat after it has
been molded. The advantage with respect to this embodiment of the
invention is that an entire set of steps is removed from the
manufacturing process. In other words, a separate sleeve does not
have to be formed and then placed inside the barrel of the bat but
rather, in this embodiment of the invention, the bat is molded
right around the mandrel. The layup of the various layers is
similar to that shown in FIG. 11 which is used to form a separate
sleeve in another embodiment. Now turning to FIGS. 15 and 17, the
end of the mandrel 1520 which is near the tapered portion 1714 of
the mold which corresponds to the taper on the finished bat, is
also tapered so as not to produce a weak spot in the molded
material which is placed over the mandrel and over the layers that
are laid up atop the mandrel. In other words, the mandrel 1520 has
an end 1720 which has a feathered layer of several layers of
material used to form the bat. The feathering prevents a thinner
portion in the wall of the bat near the end of the mandrel or near
the end 1720 of the mandrel that is near the taper 1714. The end of
the mandrel is tapered or feathered and more specifically, the end
of the layer atop the mandrel is layered or feathered so that there
is no weak portion or weak spot formed.
[0066] FIG. 16 shows a top view of a sheet used to wrap about the
mandrel 1520. The sheet 1600 is cut into two portions 1610 and
1620. The sheet is cut along a diagonal line 1630. The dimensions
of 1610 and 1620 are set so that the two halves, when rolled or
applied to the mandrel 1520, will roll on with a taper due to the
diagonal cut. The ends 1612 and 1622 of the sheet will each be laid
up on the end of the mandrel which is toward the end of the barrel
of the bat. The portion along the diagonal cut 1620 will be laid up
or placed at the end 1720 of the layers or of the mandrel 1520.
Advantageously, by making a diagonal cut when the layers are placed
upon the mandrel, it is self-tapering. Furthermore, by placing the
cut, the sheets 1600 used to form the layup on the mandrel 1520,
can be made to be self-tapering without wasting any extra material.
The length of the sheet 1610 between the end 1612 and the cut line
1630 is shorter than the length between the end 1622 and the cut
line 1630. Therefore, the portion 1620 will be placed on the
mandrel 1520 first and rolled on and the edge 1630 will
self-feather or self-taper. The other sheet 1610 will be then
placed on the mandrel and the longest dimension between the end
1612 and the cut line 1630 will be used as the starting point so
that the sheet or portion of the sheet 1610 will also self-feather
as it is placed upon the previous sheet and the mandrel 1520.
[0067] FIG. 18 is a schematic view of one embodiment of a fixture
1800 for measuring the flexibility of a bat 1810. The fixture 1800
includes a base 1820 which includes an upright 1822 attached to the
base and a datum 1824 also attached to the base 1820. The datum
1824 is spaced away from the upright 1822. Attached to the upright
1822 is a load arm 1830. The upright 1822 has an opening 1823
therein. The load arm 1830 is attached to the upright by a pivot
pin 1832. The pivot pin 1832 allows the attached end of the load
arm 1832 to pivot about the opening 1823 in the upright 1822. A
dial indicator 1840 is positioned between the upright 1822 and the
datum 1824 and near the load arm 1830. The dial indicator 1840 is
placed so that when the bat 1810 is placed in the fixture 1800, the
dial indicator 1840 contacts the bat 1810 near the load arm 1830.
Positioned at or near the free end of the load arm 1830 is a load
cell 1850. The load cell 1850 produces a specified load on the free
end of the load arm 1840. The distance between the pivot point at
the center of the pivot pin 1832 and the point on the load arm 1830
where the load cell 1850 acts is designated as dimension "A". The
distance between the pivot point at the center of the pivot pin
1832 and the point where the load arm 1830 contacts the bat 1810 is
designated as dimension "B". The distance between the end of the
base 1820 nearest the upright 1822 and the datum 1824 is designated
as dimension "C". Of course, different embodiments of the fixture
1800 have different dimensions (A, B, C). In the one embodiment
shown in FIG. 18, the dimensions are as follows:
[0068] A=17{fraction (9/16)} inches
[0069] B=23/4 inches
[0070] C=4 inches
[0071] In operation, a procedure is set up to test the bat 1810 for
flexibility. The procedure includes placing the bat in the fixture
1800. The bat 1810 is placed on the base 1820 and in contact with
datum 1824. Next, the load cell 1850 applies 10 pounds of force at
load end or free end of the load arm 1830. The dial indicator 1840
and the load cell 1850 are each zeroed. Next, the load cell 1850
applies 60 pounds of force at load end or free end of the load arm
1830. The dial indicator 1840 is then read to determine the amount
of deflection of the bat at the point or in the area where the load
arm 1830 contacts the bat 1810. This procedure is repeated a number
of times around the circumference of the bat 1810. The average
value is then used to determine a number to indicate the
flexibility of the bat 1810. One example of a calculation of such a
number includes dividing the load placed on the arm by the load
cell 1850 by the amount of deflection indicated by the dial
indicator 1840. In this example, the load of 60 lbs is divided by
the deflection in inches (60 lbs./0.0575"=1043 lbs./in or 1043
Flex) to yield a flex indication number of 1043. It is contemplated
that other testers or fixtures could be used to determine
flexibility of the bat 1810 under test without departing from the
spirit of this invention.
[0072] Of course, the amount flexibility of a bat is linked to bat
performance. Performance is also determined by the distance a
standard ASA softball can be hit as well as the amount of "sting"
or vibration within the bat. Using the fixture 1810 described in
the example above bats having a flexibility value in the range of
600 to 1200 have good performance characteristics. Bats having a
flexibility in the range of 1000 to 1200 units also have good
performance characteristics.
[0073] Advantageously, the composite material has a lower density
than metals used to make bats, such as aluminum or titanium. As a
result, more material can be used resulting in a more durable bat
for a given weight of bat. The composites also have a higher
strength than aluminum and titanium and their alloys. Therefore, a
stronger bat can be produced. In addition, the composite does not
dent and therefore more energy is transferred to the ball. There is
less, if any, energy wasted on denting the bat or the inner sleeve.
Therefore, the inventive bat hits farther than a wooden or metal
bat or bat having metal parts. The additional flexibility of the
composite material forms a bat with higher performance which hits
better. Furthermore, the inventive bat has a durability advantage
since the bat does not dent.
[0074] It is to be understood that the above description is
intended to be illustrative, and not restrictive. Many other
embodiments will be apparent to those of skill in the art upon
reviewing the above description. The scope of the invention should,
therefore, be determined with reference to the appended claims,
along with the full scope of equivalents to which such claims are
entitled.
* * * * *