U.S. patent number 3,801,098 [Application Number 05/218,155] was granted by the patent office on 1974-04-02 for metal baseball bat.
This patent grant is currently assigned to N L Industries, Inc.. Invention is credited to Donald Gildemeister.
United States Patent |
3,801,098 |
Gildemeister |
April 2, 1974 |
METAL BASEBALL BAT
Abstract
A foam filled metal bat is disclosed. The bat comprises a die
cast, ball-bat shaped hollow tube of substantially uniform wall
thickness having an integrally cast knob over an end of a handle
portion. The end of a club portion of the tube is open. A rigid
urethane foam extends within the tube from the knob end up to and
contiguous with a cap inserted in the open club end. The rigid foam
forms a bond with the tube walls and the cap portion which may be a
semi-rigid urethane foam or a plug of rubber or metal. A wire
extending axially within the rigid foam extends the length of the
bat and is anchored at its ends adjacent the integral knob and
cap.
Inventors: |
Gildemeister; Donald (Toledo,
OH) |
Assignee: |
N L Industries, Inc. (New York,
NY)
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Family
ID: |
26876431 |
Appl.
No.: |
05/218,155 |
Filed: |
January 17, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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180555 |
Sep 15, 1971 |
3727295 |
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Current U.S.
Class: |
473/520; 473/566;
273/DIG.8 |
Current CPC
Class: |
A63B
59/51 (20151001); A63B 59/50 (20151001); Y10S
273/08 (20130101); A63B 2102/18 (20151001) |
Current International
Class: |
A63B
59/00 (20060101); A63B 59/06 (20060101); A63b
059/06 () |
Field of
Search: |
;273/67R,72R,72A,8R,8B,81R,82R,82A,82B,DIG.8 ;264/45-54 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Pinkham; Richard C.
Assistant Examiner: Apley; Richard J.
Attorney, Agent or Firm: Owen; Allen Emch; Richard D.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part of my copending application Ser. No.
180,555, filed Sept. 15, 1971 now U.S. Pat. No. 3,727,295.
Claims
What I claim is:
1. A foam filled metal bat comprising, in combination, an elongate
die cast magnesium tube having a club portion of one diameter, an
intermediate portion, and a handle end of a reduced diameter, said
club portion terminating at one end at the club end and at its
other end at said intermediate portion, a core of rigid foam within
said elongate tube, and a plug comprising a rubber-like member
having an outer cap portion extending beyond said club end of said
elongate tube and an axially extending inner portion within said
club portion said axially extending portion having a wall adjacent
to, but spaced apart from the inner wall to a point closely
adjacent said club end whereby said rigid foam extends between said
wall of said plug inner portion and said inner wall of said club
portion, bonding said axially extending inner portion to said core
to form a high-impact resistant unitary structure.
2. A metal bat according to claim 1 further comprising an elongate
member extending lengthwise within said core for maintaining said
bat as a unitary structure in the event that said bat be broken
apart.
3. A foam filled metal bat according to claim 1 wherein said plug
further has an axially extending hollow plug portion therewithin,
said hollow plug portion having an inner surface in contact with
said foam and forming a bonding relationship along said inner
surface.
4. A foam filled metal bat comprising, in combination, an elongate
die cast magnesium tube having a club portion of one diamter, an
intermediate portion, and a handle end of a reduced diameter, said
club portion terminating at one end at the club end and at its
other end at said intermediate portion, a core of rigid foam within
said tube, and a plug at an open portion of said club portion, said
plug comprising a semi-rigid urethane foam having an outer cap
portion extending beyond said club end and an axially extending
inner portion, said inner portion extending from said cap portion
into contact with said rigid foam core forming a bond along an
inner face between said inner portion and said core to form a high
impact resistant unitary structure.
Description
BACKGROUND OF THE INVENTION
Metal ball bats, such as those approved for use by the Amateur
Softball Association, are advantageous over wooden bats because
they do not chip, crack or split. A metal bat, however, is
inherently subject to denting upon impact with a baseball or
softball. Furthermore because the bats are generally hollow and
tubular in shape, vibrations within the bat handle as well as
objectionable sounds will be created upon impact with a ball.
Prior art metal bats such as those disclosed in U.S. Pat. Nos.
1,499,128 to Shroyer, 1,611,858 to Middlekauff and 3,479,030 to
Merola, have provided various means for eliminating these inherent
problems with metal bats. Generally the provision of rubber sound
deadening clubs, reinforcing sleeves and wooden handle inserts have
been provided in order to simulate the impact characteristics of
wooden bats. Several problems remain unsolved with these prior art
bats. For example, it has been found that deformation of the bat
under relatively high impact with a ball often causes dislodging of
rubber plugs placed in the bat end as sound deadening devices and
strengthening members. It has also been found that the use of an
insert within the bat tube alone does not adequately strengthen the
bat against shocks caused by vibrations.
The present invention provides a means of solving the above
mentioned problems by use of expanded foam within the hollow
bat-shaped tube. The foam bonds with the metal tube as well as the
cap portion to provide a resilient and extremely strong unitary
structure.
SUMMARY OF THE INVENTION
The invention is a foam filled metal bat comprising a die cast
generally elongate metal tube of substantially uniform wall
thickness having a club end of one diameter and a handle end of
reduced diameter. A rigid expanded foam core, such as urethane
foam, is placed within the hollow elongate tube extending from an
integrally cast knob portion on the handle end of the bat to a plug
in an open end in the club portion of the bat. The core forms a
rigid bond between the interior bat walls and the plug. An elongate
member capable of accepting a tension force, such as a wire
extending the axial length of the bat within the foam core is
anchored at its ends adjacent the knob portion and plug. The plug
can be a rubber fitting having a cap portion whose outside diameter
is equal to the outside diameter of the club portion and a hollow
plug portion extending axially within the tube. The rubber plug
portion is cleated on the exterior surface with respect to the wall
of the tube and has a smooth hollow inner surface. When foam is
placed around the area of the plug, a bond is formed between the
rubber plug and the foam to form a unitary structure. A second
embodiment of the invention utilizes a molded semi-rigid urethane
foam plug having a cap portion whose outside diameter is equal to
the outside diameter of the open club end and a solid plug portion
extending within the tube and bonded to the rigid urethane foam.
The preferred foams for use in the second embodiment are of
significantly different densities. The center of balance of the bat
structure may thereby be predetermined by proportioning the
respective amounts of rigid and semi-rigid foams within the
bat-shaped tube.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal sectional view of a foam filled metal bat
embodying the present invention;
FIG. 2 is a longitudinal section of a club end of one embodiment of
the foam filled metal bat of the present invention;
FIG. 3 is a longitudinal section of a club end of a second
embodiment of a foam filled metal bat of the present invention;
and
FIG. 4 is a longitudinal section of a foam filled metal bat of the
present invention showing two different foams of different
densities therein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a foam filled metal bat 10 comprising a die
cast, elongate hollow metal tube 11 is shown. The tube 11 is
preferably of a magnesium alloy and has a club portion 12 and a
handle portion 13 with an integral knob 14 on the end of the handle
portion 13. The tube 11 is cast to form a uniform wall thickness
throughout. A plug 15 is inserted in an open end of the club
portion 12. In one embodiment of the invention, as shown in FIG. 3,
the plug 15 comprises a rubber fitting having a cap portion 16
whose outside diameter is equal to the outside diameter of the club
portion 12 and an axially extending tubular insert portion 17
having a cleated or ribbed outer surface 18 opposite the inner wall
of the tube 11 and a hollow inner surface 19. A rigid urethane foam
core 20 extends within the tube 11 from the integral knob 14 to and
around the plug 15.
An elongate member capable of accepting a tension force and made of
any suitable material having high tension strength, extends the
axial length of the tube 11, within the foam core 20. In the
preferred embodiment, a wire 23 is used. The wire 23 is anchored in
the foam core 20 by means of an L bend in the opposite ends of the
wire adjacent the integral knob 14 and the plug 15 respectively.
Should the tube 11 and the core 20 shear or otherwise part upon
extreme impact, the sheared parts of the bat 10 will be held
together by the wire 23, thus preventing injury to individuals near
a user of the bat.
It has been found that any of the several types of foams are
suitable for the present invention and that rigid urethane foams
are especially suitable. These foams are generally formed by the
use of various polyols and catalysts under various reaction
conditions. Density of the rigid foam generally ranges from 12 to
15 pounds per cubic foot. The resulting rigid foam core 20, while
being fairly light weight, has sufficient compression resistance to
withstand the shock of impact, and is capable of bonding itself to
areas within the tube 11. Since rigid urethane foam also readily
foams in place in a closed cavity, the reactive liquid will rapidly
flow into the bat 10 and foam to fill all areas to form a strong,
seamless core.
A preferred foam for use in the present invention is a rigid
urethane foam having an integral skin. The foam system forms its
own skin, generally designated by reference numeral 20a in FIGS. 2
and 3 which precisely conforms to the mold surface defined by the
interior of the tube 11. The rigid skin is virtually bubble-free
and foams a sandwich core structure of a lower density core within
the bubble-free skin.
Thus the outer skin 20a is a reinforcing layer of relatively high
density, strong and impact resistance material adjacent the inner
wall of the tube 11 backed up by the core of less dense but shock
absorbing foam. The lower density inner core within the bubble-free
skin includes a number of trapped air cells to provide sound
deadening means for the bat structure.
The rigid foam is molded within the tube 11 to form the core 20
after the rubber plug 15 is inserted into the open end of the club
portion 12. The reactive liquid is injected in the tube 11 through
an opening 21 in the knob 14. The expanding foam flows around the
cleated outer surface 18 and the hollow inner surface of the insert
portion 17 to form a bond with the plug 15. Once the foam core 20
has cured and solidified, the tube 11 and the plug 15 are bonded
into a rigid unitary structure.
Referring to FIG. 2, a second embodiment of a foam-filled metal bat
of the invention is shown. In this embodiment, the plug 15a
comprises a molded-in-place, semi-rigid, resilient fitting having a
cap portion 16a whose outside diameter is equal to the outside
diameter of the club portion 12 and a solid, axially extending
insert portion 17a extending within the open end of the club
portion 12 to the rigid urethane foam core 20. A bond between the
rigid core 20 and the plug 15a is formed along the interface 22
between the insert portion 17a and the core 20.
The preferred resilient semi-flexible foams for use in this
embodiment have high load bearing properties but relatively low
densities. This is necessary because the bats are often dropped or
intentionally pounded on their ends so that a resilient plug is
required. The plug is installed by molding it in place. Molding can
be accomplished either by first pouring the integral-skin, rigid
core 20 and then pouring and molding the semi-rigid urethane plug
15a in place or vice versa.
Because of the difference in densities of the semi-rigid foam plug
15a and the integral-skin rigid urethane foam core 20, the center
of balance or thus the center of percussion of the bat structure 10
can be determined by proportioning the relative lengths of the
insert portion 17a and the core portion 20. Thus, if the plug 15a
is comprised of a heavier foam than the core 20, by lengthening the
axial length of the plug 15a the center of percussion can be moved
a predetermined distance towards the plug end of the bat 10. If the
difference in densities is reversed, the opposite effect, of
course, takes place. For example, in FIG. 4, the insert portion 17a
of the plug 15a extends axially from the club end of the bat 10
well into the tube 11 so that the center of percussion will be
moved substantially to the left as represented by the relative
lengths of portions A.sup.1 and B.sup.1 in order to conform to FIG.
4, assuming that the foam comprising the plug 15a is less dense
than the foam comprising the core 20. This enables the manufacturer
to provide a series of bats with the same external shell but having
a variety of balance characteristics.
It is to be understood that the present invention contemplates the
use of any suitable expandable foam to form the core 20 and plug
15a elements which will lend the qualities of high resistance to
impact, deformation, and breakage to the metal bat structure of the
invention. Selection of the particular foams and the manner of
their installation will be apparent to those skilled in the
art.
Various obvious modifications from the above described preferred
embodiments may be made without departing from the scope of the
following claims.
* * * * *