Apparatus for making a mold by heat shrinking

A reinforced wood bat has a solid wood core with the same shape as standard wood bats but with slightly smaller dimensions. One or more continuous, uninterrupted layers of a conformable fabric sleeve, constructed of high strength fibers, snugly fitting over substantially the entire outer surface of the core forms a preformed bat assembly. The fabric sleeve is dimensioned to expand slightly over the barrel of the core and compress over the handle of the core. A fiberglass braided sleeve, with strands initially aligned at about +45.degree./-45.degree. orientation, is preferred. When the braided sleeve strands are tensioned over the handle portion, they align more longitudinally, and tend to lock, which significantly increases the reinforcing strength in the handle portion of the bat. An epoxy resin, which self-cures at or near room temperature, laminates and bonds the sleeve layers to the wood core to the full size dimension specified for wood bats. The preferred braided sleeve can be applied to the wood core using a hollow application tube, which applies the sleeve to the wood core in double layers, while at the same time aligning the fabric strands in the desired orientations. A molding technique heat shrinks conventional high shrink plastic tubing into close fitting contact with the preformed bat assembly. The shrunk tubing then serves as the mold for laminating and bonding the fabric sleeve layers to the core with the curable resin.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to wood bats for striking a 
baseball, softball or the like that are reinforced around their outer 
surface and methods for their manufacture. More specifically, the present 
invention is directed to solid wood bats and methods for making solid wood 
bats that are reinforced around their periphery from the knob or butt end 
to the top or outer end with a covering of composite material, including 
high strength fibers and resin, laminated to the external surface of a 
wood core. The fiber strands in the barrel portion of the reinforced bat 
are in the form of a diagonal mesh and the fiber strands in the handle 
portion are more lengthwise of the bat. 
2. Description of the Prior Art 
Baseball and softball bats have been constructed of wood since the 
inception of organized baseball games and leagues. Wood bats have been 
made using conventional lathe techniques and standard external dimensions 
have been developed along with standard weight characteristics. Also, 
hollow aluminum bats have been developed and are used by many younger 
players and are required by certain regulations relating to certain 
leagues and age groups. Additionally, hollow plastic bats have been 
developed which are used by younger age groups for practice and training 
with the hollow plastic bats being normally used with lightweight hollow 
plastic balls, rubber balls and the like. 
The following prior patents disclose various developments in ball bats. 
______________________________________ 
U.S. patents 
1,499,128 3,779,551 4,241,919 
1,611,858 3,811,596 4,744,136 
3,116,926 3,861,682 4,763,899 
3,727,295 3,955,816 4,844,460 
3,963,239 5,114,144 
Canadian Patent 
962291 
______________________________________ 
The primary drawback of solid wood bats is that they are relatively 
expensive and they frequently break in use. Therefore, substantial efforts 
have been undertaken over the past many years to develop a reinforced 
wooden bat which has the desired weight, size, strength, stiffness and 
flexibility for superior performance characteristics within the allowable 
weight and size parameters, but has a longer life than either the standard 
solid wood bat or extruded aluminum bats. For example, approved wood bats 
can be no more than 2.75 inches in diameter. 
One such prior effort is disclosed in Wheeler et al. U.S. Pat. No. 
3,129,003 in which a fiberglass sleeve is pressed tightly on the handle 
portion of the wood bat and a plastic coating is applied to the sleeve to 
fix the sleeve in place. In Baum U.S. Pat. No. 5,114,144, layers of resin 
impregnated knitted or woven cloth made from high strength fibers are 
applied to a central core in the shape of a bat made from foamed plastic 
or extruded aluminum. An outer layer of resin coated wood veneer is 
applied and the composite is placed within split molds which are pressed 
together while the resin is allowed to set to form a unitary mass. 
Costopoulos U.S. Pat. No. 3,598,410 discloses a wooden bat comprised of a 
plurality of individual laminae spirally wrapped in surface grooves with a 
high tension multi-fiber filament. Finally, Seki U.S. Pat. No. 5,301,940 
discloses a resin injection technique to apply a continuous reinforcing 
fiber and molding material to the outside surface of a bat core prepared 
using a meltable material or a foamed resin. 
None of the prior art patents, however, discloses a reinforced wood bat 
having the characteristics of the present invention. Specifically, the 
prior art does not disclose a reinforced solid wood bat which has a 
continuous sleeve constructed of high strength fibers resin bonded to 
substantially its entire outer surface. Further, the prior art does not 
disclose an arrangement in which a braided sleeve is applied to a solid 
wood core in at least two layers substantially covering the entire outer 
surface of the bat. In addition, the prior art does not disclose an 
arrangement in which a predetermined standard size of wood bat is formed 
by a cut down wood core having slightly smaller dimensions and a composite 
high strength sleeve that is bonded to the surface of the cut down wood 
core in order to return the completed bat to the standard dimension size 
specified for the original wood bat. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a cut down solid wood core having 
the same shape as a wood bat is prepared with slightly smaller dimensions 
than the standard dimension size specified for conventional wood bats. The 
wood core is prepared with the lathe support extensions or studs left 
thereon. The core is then covered with one or more layers of a continuous 
conformable fabric sleeve formed from strands of high strength fibers, 
preferably a fiberglass braided sleeve, to form a preformed bat assembly. 
Each layer of the fabric sleeve is applied in forming the preformed bat 
assembly to snugly fit over substantially the entire outer surface of the 
wood core and to align the strands to substantially increase the 
longitudinal strength of the braid along the handle portion of the bat. An 
appropriate curable resin, preferably an epoxy resin which self-cures at 
or near room temperature, is then applied to the high strength fiber 
sleeve layers of the preformed bat assembly and cured to laminate and bond 
the sleeve layers to the core in a size dimension equal to that specified 
for wood bats. 
In the preferred embodiments of the invention, the fiberglass braided 
sleeve, or other conformable fabric sleeve, has a substantially uniform 
diameter. The uniform internal diameter of the sleeve is slightly smaller 
than the diameter of the core in the barrel portion and substantially 
greater than the diameter of the core in the handle portion. The sleeve is 
also capable of expanding in diameter upon force in the radial direction 
and to contract in diameter upon tension or twisting in the longitudinal 
direction. Preferably, the sleeve has its strands aligned at about a 
+45.degree./-45.degree. orientation to its longitudinal axis. 
Accordingly, when a layer of the sleeve is applied over the core, the 
sleeve expands slightly over the core in the barrel portion, thus causing 
the strands to tend to increase their orientation to greater than 
+45.degree./-45.degree.. Meanwhile, when each sleeve layer is in position 
around the outer periphery of the wood core, the core can be twisted or 
rotated with respect to the sleeve to place the sleeve under tension in 
the longitudinal direction. This twisting causes the sleeve to contract 
and snugly fit around the outer or top end of the bat. Similarly, the 
strands in the handle portion are tensioned or twisted to cause the sleeve 
to compress and snugly fit around the handle portion of the bat. 
Importantly, this tensioning and contraction of a braided sleeve around 
the handle portion of the wood core alters the fiber strand orientation 
along the handle portion. In fact, it has been discovered that when using 
a braided sleeve the fabric strands assume an orientation much closer to 
the longitudinal axis of the bat in the handle portion and become 
essentially locked with respect to each other. This more longitudinal and 
locked orientation significantly increases the tensile strength of the 
braided sleeve along the longitudinal axis of the handle, where the bat is 
otherwise the weakest. When laminated and bonded to the core with the 
curable resin, this favorable strand orientation becomes molded into the 
bat. Such an arrangement significantly enhances the strength qualities of 
the bat. 
The present invention also includes a unique method for making the novel 
wood bat described herein. Generally, the method starts out with the 
formation of the solid wood bat core from a standard bat billet using 
conventional bat forming equipment such as a lathe or the like. However, 
for the present invention, the wood core is turned down to slightly 
smaller dimensions than prescribed for a standard wood bat over its entire 
surface in order to accommodate the fiberglass sleeve layers. In addition, 
the lathe support extensions or studs are left on. 
Several longitudinal grooves are then cut symmetrically around the wood 
core along the handle portion to assist in applying the curable resin in 
accordance with the present invention. Preferably, the wood core is 
treated to drive out air from the wood and a resin primer is applied to 
the core surface. The preformed bat assembly is then formed by applying 
one or more layers of the continuous fiberglass braided sleeve onto the 
wood core by use of a hollow application tube. Preferably, two layers of 
the fiberglass sleeve are applied. This is accomplished in accordance with 
the present invention by placing the sleeve on the outside of the 
application tube, with one end of the sleeve closed over the open mouth of 
the tube. 
The handle end of the wood core is pushed into the open end of the 
application tube while restraining the braided sleeve as it comes off the 
exterior of the tube and onto the core. This restraint puts the sleeve 
under longitudinal tension as it goes over the handle portion of the core 
and causes the braid to elongate and snugly fit over the handle portion. 
When the core is all the way into the tube, the core is turned by using 
the barrel end support extension as a handle. This turning action forces 
the sleeve to draw in on the outer end of the core into contact with the 
circular base of the extension where it meets with the barrel end of the 
bat. 
This drawing in of the sleeve around the outer end of the core allows the 
core to be withdrawn from the tube without the sleeve becoming loose or 
falling off, while at the same time dispensing a second layer of the 
fiberglass sleeve over the first layer. The end of the second layer now 
extending over the knob is then tensioned so as to draw in the second 
layer on the handle portion of the core and first layer. The preformed bat 
assembly is now ready for further processing. 
In accordance with the present invention, a preferred molding technique 
involves the heat shrinking of conventional high shrink plastic tubing 
into close fitting contact with the preformed bat assembly. The shrunk 
tubing can then serve as the mold for laminating and bonding the 
fiberglass sleeve layers to the core with curable resin. The tubing is 
also preferably shrunk with a suitable tubular extension at the barrel end 
to serve as a receptacle for receiving and holding the resin as it is 
slowly fed into the tubular mold to wet-out the fiberglass sleeve layers 
prior to curing. Because of the differential between the diameters of the 
handle portion and the barrel portion of the bat, it has been discovered 
that the method of shrinking the plastic mold tubing down onto the 
preformed bat assembly requires not only heating and shrinking of the 
plastic mold tubing during the heat shrinking process, but also 
simultaneous stretching. This simultaneous stretching has been found 
necessary in order to sufficiently shrink the mold tubing around the 
handle portion of the preformed bat assembly. 
The curable resin is next slowly fed into the tubular mold, preferably 
through the shrink wrap tube extension, in order to wet-out the fiberglass 
sleeve layers. Also, preferably, an elongated piece of ash wood is 
inserted into the resin in the tube extension to act as a heat sink. Air 
pressure is also preferably applied to force the resin to wet-out the 
fiberglass sleeve layers of the preformed bat assembly in a reasonable 
period of time. 
After the fiberglass sleeve layers have been wetted out, the preformed bat 
assembly in the plastic tubular mold may be turned upside down and held by 
a fitting which holds the bat just below the knob. By so doing, the 
uncured resin and fiberglass better fill the handle/knob interface. Once 
the resin has cured, the plastic tubular mold or heat shrink wrap is 
removed. The extension supports are then cut off and the exposed bat ends 
are dressed. The handle is then either sand blasted or sanded to give it a 
rougher texture. 
It is therefore an object of the present invention to provide a reinforced 
wood bat for striking a baseball, softball or the like which is 
constructed from a wood bat core that is the same shape and configuration 
as a conventional wood bat but has external dimensions slightly less than 
the standard size conventional wood bat and a reinforcing composite 
laminant containing high strength fibers bonded to substantially all of 
the external surface of the wood core to form a finished bat having the 
same external dimensions as a standard size conventional wood bat. 
Another object of the present invention is to provide a reinforced wood bat 
as set forth in the preceding object in which the reinforcing composite 
laminant is one or more continuous, uninterrupted layers of a fabric 
sleeve formed from strands of high strength fibers impregnated with a 
clear curable resin which coacts with the wood core to provide a wood bat 
having substantially the same appearance and impact characteristics as a 
conventional wood bat but is subject to significantly less breakage and 
damage due to contact with batted balls. In fact, actual testing to date 
of bats of the present invention has resulted in virtually no broken bats. 
Yet another object of the present invention is to provide a reinforced wood 
bat as set forth in the preceding objects in which at least two 
continuous, uninterrupted layers of a reinforcing braided sleeve 
constructed of fiberglass strands are bonded to substantially the entire 
outer surface of the wood core. 
A further object of the present invention is to provide a reinforced wood 
bat in accordance with the preceding objects in which the high strength 
fiberglass strands are oriented toward the longitudinal, or 0.degree., 
axis of the bat in the handle portion and oriented in an approximately 
+45.degree./-45.degree. diagonal mesh in the ball impacting barrel portion 
of the bat to provide enhanced impact resistance in the barrel portion and 
enhanced break resistance in the handle portion of the bat. 
Still another object of this invention is to provide a reinforced wood bat 
as described in the preceding objects in which lathe support extensions 
assist in applying and orienting the fiberglass strands onto the wood core 
and in laminating and bonding the reinforcing composite laminate to the 
wood core. 
A still further object of the present invention is to provide a reinforced 
wood bat as described in the preceding objects in which longitudinally 
extending grooves are cut symmetrically around the handle portion of the 
bat to improve the bonding of the reinforcing composite laminate to the 
wood core. 
Yet a further distinct object of this invention is to provide a method of 
making a reinforced bat in which the wood core in the shape of a bat is 
formed with smaller external dimensions and one or more continuous layers 
of a fiberglass sleeve are positioned over substantially the entire core 
to form a preformed bat assembly. The preformed bat assembly is then 
placed in a mold, curable resin is applied to the fiberglass sleeve 
layers, and the resin cured to bond and laminate the fiberglass layers to 
the exterior of the bat core thereby forming a completed reinforced wood 
bat that has external dimensions exactly the same as a conventional wood 
bat. 
A still further object of the present invention is to provide a method of 
making a reinforced wood bat using a preformed bat assembly in which the 
wood core is formed in a conventional manner including the lathe support 
extensions or studs extending longitudinally from each end of the wood 
core and at least two layers of a fiberglass braided sleeve are stretched 
over substantially the entire external surface of the wood core by using 
an application tube and twisting the core with the support extension as a 
handle. The fiberglass sleeve is then impregnated with a curable resin, 
which is then cured to laminate and securely bond the reinforcing sleeve 
to the wood core to form an integral bat structure. 
Yet another object of this invention is to provide a method of making a 
reinforced bat in which a mold for applying a preferred epoxy resin to a 
preformed bat assembly having glass fibers positioned on the surface of a 
wooden bat core is formed from high heat shrink tubing by simultaneously 
stretching and heat shrinking the high shrink plastic tubing into close 
fitting contact with the preformed bat assembly to form a plastic tubular 
mold, while at the same time forming a hollow tube extension for inserting 
the curable resin into the tubular mold and for applying head pressure to 
force the resin to wet out the glass fibers before curing. 
Still yet another object of the present invention is to provide a method of 
making a reinforced wood bat in accordance with the preceding object in 
which a heat sink is inserted in the hollow tube extension of the plastic 
tubular mold after the epoxy resin has been poured therein in order to 
slow the exothermic reaction of the epoxy resin and allow sufficient time 
for the resin to wet out the glass fibers of the preformed bat assembly 
before curing. 
A final object of the present invention to be specifically set forth herein 
is to provide a method of making a reinforced wood bat in accordance with 
the two preceding objects in which the plastic tubular mold containing the 
preformed bat assembly with the glass fibers wetted out with the epoxy 
resin is turned upside down and held by fittings which hold the bat just 
below the knob in order to force the uncured resin and glass fibers to 
better fill in the handle/knob interface. 
These together with other objects and advantages which will become 
subsequently apparent reside in the details of construction and operation 
as more fully hereinafter described and claimed, reference being had to 
the accompanying drawings forming a part hereof, wherein like numerals 
refer to like parts throughout.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In describing the preferred embodiments of the present invention, such as 
illustrated in the drawings, specific terminology will be resorted to for 
the sake of clarity. However, the invention is not intended to be limited 
to the specific embodiments illustrated and described and terms so 
selected; it being understood that each specific term includes all 
technical equivalents which operate in a similar manner to accomplish a 
similar purpose. 
Referring now to FIG. 1, the reinforced bat of the present invention is 
generally designated by reference numeral 10 and includes a wood core 12 
and a composite laminant 14. The composite laminant 14 is formed of one or 
more continuous, uninterrupted layers of a conformable fabric sleeve which 
covers substantially the entire outer surface of the wood core 12. The 
sleeve is constructed of high strength fiber or fibers, preferably glass 
fibers, also known as fiberglass, and preferably in the form of a woven 
braid. The braided sleeve is impregnated with a curable resin which bonds 
and laminates the reinforcing layer or layers to the external surface of 
the wood core 12. 
The bat 10 is also constructed in a manner to conform with standard 
dimensional characteristics and standard physical characteristics of a 
conventional wood bat. More specifically, conventional wood bats are 
constructed in various standard lengths with standard weight 
characteristics and standard external diameter and tapering 
characteristics. The bat 10 is constructed to conform to such standard 
characteristics. As is conventional, the bat 10 includes a handle portion 
16 with a knob 18 on the end thereof with the handle portion tapering 
outwardly and merging into a barrel portion 20 which terminates in a tip 
or outer end 22. 
The wood core 12 is formed in the conventional manner of a wood bat by the 
use of conventional lathe operations, and also includes a handle portion 
17, a barrel portion 19, and a knob 21 at the end of the handle portion. 
However, as illustrated in FIG. 2, the wood core 12 is formed with 
external dimensions slightly less than the external dimensions of a 
conventional wood bat. In FIG. 2, the broken line indicated by reference 
number 24 defines the outline of a conventional wood bat thereby 
illustrating that the wood core 12 is formed with slightly less external 
dimensions as compared to the dimensions of the conventional standard size 
wood bat. When the laminant 14 is bonded to the wood core 12, the external 
dimensions of the completed reinforced wood bat 10 are the same as a 
standard size conventional wood bat. Preferably, the lathe operation turns 
down the wood core approximately 1/10 of an inch over its entire length 
from standard wooden bat dimensions. Thus for standard wood bats having a 
diameter of approximately 2.50 inches, the diameter of the wood core 12 in 
the barrel portion 19 is preferably about 2.35-2.40 inches. 
In addition, when the cut down wood core 12 is formed in the lathe 
operations, it is formed to leave intact specifically dimensioned, 
longitudinal lathe support extensions or studs 26 and 28, which extend 
axially out of each end of the core 12, as shown in FIG. 2. The outer end 
extension or stud 28 is sufficiently sized to serve as a handle in the 
construction of the bat 10. Preferably, extension 28 is about 1 inch in 
diameter and about 2-3 inches long. Extension 26 on the knob end can be 
much smaller and is on the order of 3/4 inches in diameter and 1/2 inch in 
length. Longitudinal grooves 30 are cut in the wood core 12 along the 
handle portion 17. These grooves serve to assist in wetting out or 
impregnating the layer or layers of the fiberglass sleeve along the handle 
portion of the core. Preferably, the grooves are symmetrically placed 
around the circumference of the handle and extend from about 1 1/2 inches 
short of the knob down the length of the bat for about 15 inches, or more. 
The grooves 30 can be any effective size and shape. Four grooves about 
0.06 inches.times.0.06 inches square symmetrically spaced around the 
handle have been found satisfactory. 
The preformed bat assembly is illustrated in FIG. 3 and generally 
designated by the numeral 32. The assembly 32 is formed by covering 
substantially the entire outer surface of the wood core 12 with one or 
more continuous, uninterrupted layers of a conformable fabric sleeve 
generally designated by the numeral 34. Preferably, two continuous, 
uninterrupted layers of a fiberglass braided sleeve are snugly fitted over 
core 12, designated by the numerals 36 and 38 in FIGS. 6 and 7. Although 
two continuous layers are preferred, one continuous layer may suffice, or 
three or more layers may be utilized depending upon the density of the 
fiberglass strands and the tightness of the weave in the braid or sleeve. 
The sleeve 34 has a generally constant diameter and is braided or formed so 
that the strands are generally perpendicular to each other and at a 
generally 45.degree. angle to the longitudinal axis of the core 12, or 
+45.degree./-45.degree.. For the purpose of this invention, zero degree 
strand orientation is parallel to the longitudinal axis of the wood core 
12 or bat 10, and a 90.degree. orientation is axially around the core or 
bat in a plane perpendicular to the longitudinal axis. A strand which is 
oriented plus 45.degree. or minus 45.degree. lies in a plane which is at a 
45.degree. angle to the longitudinal axis of the core or bat and a 
+45.degree. plane is perpendicular to a -45.degree. plane. 
The preferred +45.degree./-45.degree. orientation of the strands is 
illustrated in FIG. 8 where strands 40 and 42 are generally perpendicular 
to each other and are generally in a +45.degree./-45.degree. orientation 
to the longitudinal axis of the sleeve 34. These strands 40 and 42 are 
illustrated in FIGS. 3, 4 and 5 as solid lines for simplicity in the 
drawings. The preferred form for the fiberglass sleeve 34 for a bat having 
a 2.50 inch barrel diameter is a braid having an inner diameter of about 
2.25 inches, which is slightly less than the greatest diameter of the core 
12, preferably about 2.35-2.40 inches. A preferred braid has a weight and 
density of about 26.5 feet per pound and 9 ounces per square yard and is 
made and sold by A & P Technology of Covington, Ky. 
While a braided sleeve made of fiberglass ends or strands is the preferred 
construction for sleeve 34 in order to form layers 36 and 38 of the 
present invention, a woven or knitted sleeve made of fiberglass and/or 
other high strength fiber strands can also be used within the scope of 
this invention. The woven or knitted sleeve can also be formed either with 
or without a longitudinal seam. Therefore, for the purpose of this 
invention, the term "sleeve" is intended to encompass not only the 
preferred braided sleeve, but also any woven, knitted and other fabric 
which can be constructed in a continuous, uninterrupted conformable sleeve 
of fiberglass and/or other high strength fibers. 
As previously stated, the preferred fiberglass sleeve 34 has an internal 
diameter slightly less than the outer diameter of the barrel portion 19 of 
the wood core 12. Hence, the sleeve 34 expands slightly as it is pulled 
over the barrel portion 19. This tight fitting engagement between the 
sleeve 34 and the barrel 19 tends to ensure that the generally 
+45.degree./-45.degree. orientation of the fiberglass strands 40 and 42 
remains intact, or increases slightly, along the barrel portion 19 of the 
core 12. This generally +45.degree./-45.degree., or more, orientation in 
the barrel portion 19, is illustrated by the numeral 46 in the preformed 
bat assembly 32 in FIG. 3, and in the enlarged segment in FIG. 5. 
On the other hand, the sleeve is not normally in close fitting contact with 
the core at its tip end 54 or along its handle portion 17. By rotating the 
core 12, the sleeve 34 is drawn in on the core 12 at the tip end 54. The 
drawing in of the sleeve 34 at the tip end 54 is illustrated in FIG. 5 of 
the drawings. It will there be seen that the contracted sleeve layers 
cover the entire surface of the tip end 54 except where the base 44 of 
support extension 28 extends axially from the tip end of core 12. This 
covering and fitting of the sleeve layer around the top of the tip end 54 
and snugly around the base 44 of extension 28 is accomplished in a unique 
way in accordance with the present invention, but can be achieved in any 
manner which substantially covers the tip end of the core. 
Meanwhile, tensioning a braided sleeve 34 over the handle portion 17 of the 
core causes the sleeve to stretch in the longitudinal direction over the 
handle portion. This stretching causes the fiber strands 40 and 42 in the 
handle portion to orient in a more longitudinal direction, as shown by the 
numeral 48 in FIGS. 3 and 4. This more longitudinal direction for the 
fiber strands 40 and 42 in the handle portion is substantially less than 
the normal +45.degree./-45.degree. orientation of the braid as shown in 
FIG. 8. Thus, it has been discovered that utilization of one or more 
continuous, uninterrupted layers of a braided sleeve of glass fibers or 
other high strength fibers, preferably in a +45.degree./-45.degree. 
orientation, which has an internal diameter equal to or slightly smaller 
than the barrel portion of the wood core, has significant advantages in 
producing the laminated bat of the present invention. More specifically, 
when the braided sleeve is applied to the wood core, the greater diameter 
of the barrel causes the glass fiber strands to expand beyond their 
natural +45.degree./-45.degree. orientation to an orientation equal to or 
slightly greater than +45.degree./-45.degree.. Then, as the layers 36 and 
38 are assembled on the core and the sleeve layers are stretched to draw 
in on the handle portion of the core, the strands are forced into a 
substantially more longitudinal orientation significantly less than 
+45.degree./-45.degree.. This change of orientation of the strands toward 
a 0.degree. orientation significantly increases the longitudinal strength 
of the strands, thus increasing the reinforcing effect of the glass fibers 
in the handle portion of the bat. Further, the stretching and drawing in 
of the braided sleeve tend to cause the strands in the handle portion to 
substantially lock against each other, thus further increasing the 
strength of the strands in the longitudinal direction. The preferred 
orientation of the strands in the handle portion of the bat, when locking 
occurs, is approximately +20.degree./-20.degree. to approximately 
+25.degree./-25.degree.. 
As part of the present invention, it has been discovered that continuous, 
uninterrupted layers of the preferred fiberglass braided sleeve can be 
easily and quickly applied to substantially the entire outer surface of 
the core 12 in making the preformed bat assembly 32 by use of a hollow 
application tube. This methodology is schematically illustrated in FIGS. 
9, 10 and 11, with the application tube generally designated by the 
numeral 50. The layers are preferably applied in pairs by selecting 
sufficient length of the sleeve to comprise at least two layers. The 
sleeve 34 is then placed on the outside of the application tube 50, the 
inside diameter of which is slightly greater than the largest diameter of 
the wood core. Any suitable rigid plastic tubing having the requisite 
internal diameter can be used, but clear PVC plastic is preferred. Before 
or after the sleeve 34 has been placed on the application tube 50, the 
near end is cinched together by tape or the like, as at 52 in FIG. 9. The 
sleeve 34 and application tube are then in condition to receive the wood 
core 12. 
While restraining the sleeve 34 on the outside of the tube 50, the handle 
end 17 of the wood core 12 is pushed into the cinched end 52 of the sleeve 
34 forcing the sleeve into the tube 50. This causes the sleeve 34 to draw 
off the outside of tube 50 and over the bat under tension as it is being 
pushed into the tube. This tension on the sleeve in the longitudinal 
direction tends to draw in the sleeve onto the handle portion 17 of the 
core, thus orienting the strands in the desired longitudinal direction. 
When the core 12 is all the way into the tube 50, the core is turned or 
rotated by using the barrel end support extension 28 as a handle. This 
turning or twisting action forces the sleeve 34 to draw in on the outer 
end 54 of the wood core 12. The core is turned until the sleeve draws in 
enough to engage the circular base 44 of the extension 28 where it meets 
with the outer or tip end of the core, thus completely covering the 
remainder of the core end 54. The first layer 36 of the sleeve 34 is now 
in place on the core 12. 
The amount of turning of the core 12 to obtain sufficient covering of the 
core end 54, all the way to the base 44 of the extension 28, depends upon 
the characteristics of the sleeve, including density, weave tightness, 
etc. Using the preferred fiberglass braided sleeve as described above, the 
core need be turned only about one half turn to draw the sleeve 34 in 
fully around the core end 54. This drawing in of the sleeve to the base 44 
allows the core to be withdrawn from the tube without the sleeve becoming 
loose or falling off, while dispensing the second layer 38 of the 
fiberglass sleeve 34 onto the wood core 12 as it is being withdrawn from 
the tube 50. Thus, it is possible to quickly and easily apply two 
continuous, uninterrupted layers 36 and 38 of the high strength sleeve 34 
to substantially the entire outer surface of the core 12 without 
separating the layers. In effect, second layer 38 is simply doubled back 
over the first layer 36. Additional layers can be applied either singly or 
in pairs in the same way by simply repeating the method described above. 
Further, the tubular sleeve could be continuously fed to the tube 50 from 
the non-working end. 
When the wood core 12 has been withdrawn from the tube 50, the sleeve 34 is 
cut leaving several inches extending past the support extension 26 at the 
end of the core. The end 41 of sleeve layer 38 is then tensioned with 
respect to the core 12 in order to draw the sleeve down around the handle 
portion 17 of the core and orient the strands 40 and 42 of layer 38 into 
the desired locking orientation for the handle portion 16 of the bat, as 
described above. The tensioning can be readily accomplished by holding the 
outer end 41 of layer 38 and turning the core by support extension 28 as a 
handle. Further, the tubing is drawn tightly to the base of the knob 21 to 
draw the sleeve down around the knob end. This is readily accomplished by 
placing a small piece of plastic PVC tubing 39 over the end 41 of layer 38 
and stud 26, and then pulling tightly on the braid end as the PVC tubing 
moves against the base of the knob 21. The end 41 of the braid layer 38 is 
then folded over and taped (not shown). Further tensioning of the outer 
layer 38 can be achieved, if necessary, by twisting tubing 39 down tighter 
on the base of knob 21. The preformed bat assembly 32 is now complete. 
The layers 36 and 38 of the sleeve 34 are tightly bonded to substantially 
the entire outer surface of the core 12 in forming the bat 10 by an 
appropriate curable resin. Any curable resin can be used which tightly 
bonds the fiberglass layers to the wood core and does not exhibit any 
fracturing, breaking, or shattering when impacted with hitting a ball, or 
otherwise. Further, since the reinforced bat of the present invention is 
intended to emulate a standard wood bat in appearance, a clear resin is 
preferred. Thus, the curable resin for the present invention is selected 
for clarity, fracture toughness, impact, interlaminer and interfacial 
adhesion, and high modulus to dissipate energy laterally. 
The preferred resins for the present invention are thermoset epoxy resins 
which self-cure at or near room temperature. The epoxy component is 
preferably based on 2,2'-(1,3-phenylene)bis-2-oxazoline. Other 
difunctional and multifunctional epoxy resins, with or without 
monofunctional diluents, may also be used. Applicable converters, or 
hardeners, to form the thermoset epoxy resin include multifunctional 
primary and secondary amines, Lewis acids, Lewis bases, dibasic carboxylic 
acids and anhydrides, and the like. The preferred hardeners include alkyl 
amines, such as diethylenetriamine, triethylenetetramine, 
metaxylenediamine, .alpha.-aminoethyl piperazine, and the like. 
Polyoxypropyleneamines, amidoamines, polyamides, and cycloaliphatic 
polyamines could also be used as a total converter or as a blend. The mix 
ratio would be approximately stoicheometric (except for Lewis acids and 
bases), consisting of one active amine hydrogen for every epoxy group. In 
addition to the epoxy component and the amine hardener component, a third 
component is preferably incorporated which precipates out during cure and 
forms a discrete second phase. This second phase is in the nature of small 
elastomeric balls, preferably less than 1 micron in diameter, encapsulated 
and bonded to the continuous epoxy phase. This second phase enhances 
fracture toughness, impact resistance, and improves the composite's 
resistance to premature delamination. The preferred resin materials are 
manufactured and sold by Applied Polymeric Inc. of Benicia, Calif. 
In order to assist in bonding a preferred epoxy resin to the wood bat core, 
a primer is preferably applied to the wood bat core before the fiberglass 
sleeve layer or layers are applied. The primer is selected to penetrate 
the wood and act as a coupler or interface between the wood core and the 
fiberglass. The preferred primer compositions are epoxy resin emulsions 
which exhibit low toxicity, low cost, long pot life, good wood 
penetration, Tg&gt;60.degree. C., and low viscosity. A single component 
thermoplastic epoxy, having a molecular weight of about 30,000 with 
appropriate coalescing and penetrating solvent, is especially effective. A 
two part epoxy, where the part B contains blends of alkyl amines, 
amidoamines and emulsifying surfactants may be satisfactory, but are not 
as preferred due to their two components and limited pot life. Further 
examples of primer compositions include resorcinol formaldehyde, urea 
formaldehyde and aqueous solutions of polyethylenimine hydroxymethylated 
resorcinol. The preferred primer is also manufactured and sold by Applied 
Polymeric. 
The enlarged sectional views in FIGS. 6 and 7 illustrate the intimate 
bonded and laminated relationship between the layers of composite material 
sleeve 14 and the surfaces of the wood core 12 forming the reinforced bat. 
As illustrated, the layers 36 and 38 of sleeve 34 cover the entire outer 
surface of the bat 10 except for portion 56 in the outer end 22 and 
portion 58 in the base of knob 18 where lathe extensions 28 and 26, 
respectively, have been removed in the finishing of the bat 10. Further, 
reinforcement of the knob 18 is not necessary in accordance with the 
present invention. Therefore, the reinforcing layers 36 and 38 can be cut 
at 60 where the knob 18 merges into the bottom of the handle portion 16. 
In such event, extension 26 is cut to be flush with the base of the knob 
18 when finishing the bat. In accordance with this invention, therefore, 
the reinforcing layers of the fiberglass sleeve continuously cover the 
entire outer surface of the bat 10 from at least the point where the knob 
merges with the handle 16 up to portion 56 at the outer tip of the bat. 
This continuous, uninterrupted covering is more than 99% of the entire bat 
surface, not including the knob 18. 
One conventional method for bonding and laminating the fiberglass sleeve 
layers to the wood core is illustrated in FIGS. 12, 13 and 14. The 
preformed bat assembly 32 is placed in a mold 62 including a bottom half 
64 and a top half 66 each of which includes one half of a cavity 68 
receiving the preformed bat assembly 32. The mold components are 
conventional and, when closed, an appropriate heat curable thermosetting 
or thermoplastic resin is injected through injection port 70 to fill the 
cavity 68 and fully impregnate the fiberglass sleeve layers 36 and 38 with 
the resin. The mold cavity and preformed bat assembly 32, including the 
resin impregnated layers 36 and 38, are subjected to heat and pressure 
with the heat being at a temperature to melt and fuse the resin and 
securely bond and laminate the sleeve layers to the wood core and also 
retain the fiberglass strands in the handle portion 16 in the described 
favorable orientation as indicated by reference numeral 48 and in the 
barrel portion 14 in the diagonal mesh relation as indicated by reference 
numeral 46. One known resin injection molding technique is disclosed in 
Seki U.S. Pat. No. 5,301,940, except that the molds must be reconfigured 
to accommodate the end support extensions 26 and 28. 
It is also part of the present invention to utilize a novel method for 
applying and curing an epoxy resin, such as the preferred epoxy resins 
described above, in order to fix the fiberglass sleeve layers to the wood 
core. However, in utilizing the preferred epoxy resins, a primer, such as 
a preferred epoxy primer as described above, should be applied to the wood 
core 12 before the fiberglass sleeve layers. The resin primer is applied 
after the wood core 12 is preferably heated to about 110.degree. F. The 
heating serves not only to drive out the air from the wood core, but also 
assists the penetration of the primer into the wood. Once heated, the wood 
core is dipped into the epoxy primer composition. After drying, the wood 
core is preferably dipped a second time in the primer composition, but 
this time without heating. The wood core is now primed for receiving the 
epoxy resin during the curing and molding operation. 
In accordance with the present invention, a unique molding technique has 
been discovered which facilitates the bonding and laminating of the 
fiberglass sleeve layers to the wood core in a more expeditious and less 
expensive technique than prior processes. This preferred molding technique 
involves the heat shrinking of conventional plastic tubing in close 
fitting contact with the preformed bat assembly to serve as a mold for 
application and curing of the epoxy resin. This molding technique will now 
be described by reference to illustrative FIGS. 15, 16 and 17 in which the 
plastic tubular mold is generally designated by the numeral 72. 
In order to form the requisite tubular mold 72, a properly sized hollow 
tube 74 is placed on the barrel end of the assembly 32 over the extension 
28. The tube 74 includes an elongated tube portion 76 and a short tube 
portion 78 dimensioned to fit closely over extension 28. The tube portion 
78 over the extension 28 has a smaller diameter than tube portion 76. 
Large tube portion 76 forms the open spout 80 for the mold 72, while short 
tube portion 78 forms the circular opening 81 (see FIG. 16) from the spout 
80 into the mold surrounding the preformed bat assembly. Generally, a 1 
1/2 inch cardboard hollow tube having a length of about 20 inches has been 
found satisfactory for the tube portion 76. The shorter tube portion 78 
can be easily affixed to the inside of the cardboard tube portion 76. The 
base of the tube 74 is placed in an appropriate stand (not shown) which 
supports the tube 74 in a standing vertical position. The preformed bat 
assembly 32 is then supported on the tube 74 by inserting the support 
extension 28 in the tube portion 78. 
A high shrink tubing 82 having a lay flat width of about four inches is 
then applied over both the preformed bat assembly and the tube 74. Thin 
wall PVC high shrink tubing has been found satisfactory for tubing 82. The 
high shrink tubing 82 is then shrunk down into close fitting contact with 
the outer fiberglass sleeve layer using an annular radiant heater 84 or 
the like. Preferably, the radiant heater 84 moves automatically, starting 
at the bottom of tubing 82 and moving upwardly over the preformed bat 
assembly 32 starting at the outer end. As shown in FIG. 15, the annular 
radiant heater 84 has moved substantially up the assembled structure past 
the tube 74, the barrel portion 19 and into the handle portion 17 of the 
preformed bat assembly 32. As shown, the high shrink tubing 82 has shrunk 
down into close fitting contact with the tube 74 as well as the preformed 
bat assembly 32. A suitable opening is provided for the air in the tubing 
to escape as tubing 82 is shrunk down on the tube 74 and preformed bat 
assembly 32. Once the radiant heater has made a complete pass over the 
assembled structure, and the tubing 82 has been shrunk around the knob end 
18, the hollow tube 74 is then removed leaving the preformed bat assembly 
32 encased in a plastic heat shrunken skin which forms the plastic tubular 
mold 72 with a long open tube extension 85 at the barrel end 54. 
Because there is a significant differential between the diameters of the 
handle portion 16 and the barrel portion 20 of the bat, it has been 
discovered that the method of shrinking the mold tubing down onto the 
handle portion of the preformed bat assembly requires simultaneous 
stretching and heating of the plastic mold tubing during the heat 
shrinking process. This has been found desirable in order to sufficiently 
shrink the mold tubing around the handle portion of the bat. The 
simultaneous stretching of the tubing during the heat shrinking process in 
the handle portion 16 of the bat can be achieved by any suitable 
technique. However, one simple method is to release the support of the 
tube 74 and, therefore, the assembled preformed bat assembly thereon when 
the annular radiant heater 84 has risen approximately three quarters of 
its upward course, thus leaving the preformed bat assembly 32 and tube 74 
with that portion of the tubing 82 heat shrunk thereon to freely hang with 
respect to the remainder of the tubing 82 which is supported from above. 
This gravity force on the unshrunk tubing 82 causes it to stretch as it is 
being heat shrunk by radiant heater 84 onto the handle portion. 
After the tube 74 has been removed from tube extension 85, the preformed 
bat assembly 32 within the plastic tubular mold 72 is now ready to receive 
the preferred epoxy resin 86. The components are brought to an ambient 
temperature environment. The epoxy resin components are then mixed and 
poured into the hollow tube extension 85 through open spout 80. Using the 
preferred epoxy resin, it has been found that about seven ounces of the 
mixed resin are sufficient. Preferably, an elongated piece of ash wood 88, 
about 1 inch square and 14 inches long, is inserted into the tube to act 
as a heat sink. This piece of ash wood serves to slow the exothermic 
reaction of the epoxy resin and increase the amount of working time or 
"pot life" of the resin. The open end 80 of the hollow tube extension 85 
is then placed over and locked down over a capture fixture 90 to 
pressurize the air pressure in the tube extension and plastic tubular 
mold. This head pressure forces the resin to wet-out the fiberglass sleeve 
layers in the preformed bat assembly in a reasonable period of time 
without premature curing. Preferably, an air pressure of about 10 psi is 
applied, which causes the preferred epoxy resin to completely traverse the 
length of the supported preformed bat assembly 32 and plastic tubular mold 
72, such that resin begins to drip out of the opening 92 of the molding at 
the handle end of the assembly 32, in approximately 30 to 40 minutes. As 
shown in FIG. 16, the epoxy resin has wetted out approximately the top one 
quarter of the preformed bat assembly 32 at a level designated by the 
numeral 94. This pressurization of plastic tubular molds is a form of 
composite manufacturing known in the art under the name "Resin Transfer 
Molding". 
It has been found that an ambient temperature of about 80-82.degree. F. is 
an optimum temperature for applying and curing the epoxy resin. Any lower 
ambient temperature undesirably increases the viscosity of the resin 
causing excessively long wet out time. A significantly higher ambient 
temperature will cause undesirable exothermic reaction of the epoxy, thus 
destroying the formed bat. 
After the preformed bat assembly 32 has been wetted out, it can be turned 
upside down and held by a fixture 96 which holds the bat just below the 
knob 18. (See FIG. 17.) By so doing, the uncured resin and fiberglass 
better fill the handle/knob interface. Preferably, the fitting 96 is 
shaped and heated to a temperature above 200.degree. F. so as to form a 
permanent ring at the interconnection between the top of the knob and the 
base of the handle portion 16 of the bat 10. This holding step can be 
eliminated if the fiberglass sleeve layers have been effectively saturated 
during the resin transfer molding step described above. 
Once the epoxy resin has cured, which should take approximately 1 1/2 to 2 
hours, the tubular mold 72 comprising the heat shrink wrap is removed. The 
support extensions 26 and 28 are cut off and the exposed bat ends are 
dressed. The handle can then be either sand blasted or sanded to give it a 
rougher texture. 
While the foregoing preferred embodiments have been described above using 
one or more layers of a conformable fabric sleeve made of high strength 
glass fibers, or fiberglass, it is believed that fabric sleeves made from 
other high tensile strength fibers, such as Kevlar, Spectra, carbon, nylon 
and the like, can be used in the present invention. Further, one or more 
ends or strands of such other high strength fibers can be braided, woven, 
knitted or formed into a conformable sleeve along with the fiberglass 
strands or ends within the scope of this invention. Hence, it is not 
intended that the present invention be limited to sleeves, braided or 
otherwise, made solely from glass fibers. 
In addition, the particular wood from which the wood core 12 is formed can 
be a matter of choice. High quality ash wood is customarily used to make 
quality wood bats, and such wood can be used in the present invention. 
However, lower grade ash wood may also be used for the wood core 12 in 
view of the surprisingly high superior reinforcing capability of the 
laminated fiberglass sleeve 14 of the present invention. 
The foregoing is considered as illustrative of the principles of the 
invention. Numerous other modifications and changes will occur to those 
skilled in the art. Hence, it is not desired to limit the invention to the 
exact construction and operation shown and described. All suitable 
modifications and equivalents may be resorted to, falling within the scope 
of the invention as presented.