U.S. patent application number 10/217195 was filed with the patent office on 2004-02-12 for laminated sport bat with internal chamber.
Invention is credited to Chen, Sam H., Liao, Chi-Hua.
Application Number | 20040029660 10/217195 |
Document ID | / |
Family ID | 31495170 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040029660 |
Kind Code |
A1 |
Chen, Sam H. ; et
al. |
February 12, 2004 |
Laminated sport bat with internal chamber
Abstract
Sport bat 10, made of laminated wood 50, such as of bamboo 51.
Bat 10 includes handle 45, taper portion 44 and batting portion 30.
Batting portion 30 includes one or more internal chambers 31 for
decreasing the weight of bat 10. Internal chambers 31 may be
reinforced with sleeve insert 32, rubbery coating 34, or porous
filler 33. Internal chamber 31 is disposed between taper portion 44
and sweet spot 12.
Inventors: |
Chen, Sam H.; (San Diego,
CA) ; Liao, Chi-Hua; (Taichung, TW) |
Correspondence
Address: |
CALIF KIP TERVO
6387 CAMINITO LAZARO
SAN DIEGO
CA
92111
US
|
Family ID: |
31495170 |
Appl. No.: |
10/217195 |
Filed: |
August 8, 2002 |
Current U.S.
Class: |
473/564 |
Current CPC
Class: |
A63B 59/55 20151001;
A63B 59/50 20151001; A63B 2102/18 20151001; A63B 59/52 20151001;
A63B 60/54 20151001; A63B 2102/20 20151001 |
Class at
Publication: |
473/564 |
International
Class: |
A63B 059/06 |
Claims
I claim:
1. A sport bat having a longitudinal axis and a sweet spot,
including: a body, including a handle; a taper portion attached
above said handle, and a batting portion attached above said taper
portion, including: an internal chamber that decreases the weight
of said sport bat; including: an internal space, and a wall
surrounding said internal space; including: a bottom end disposed
above said taper portion; and a top end disposed below said sweet
spot.
2. The sport bat of claim 1, said internal chamber including: a
sleeve insert in contact with said wall for reinforcing said
internal chamber.
3. The sport bat of claim 1, said internal chamber including: a
shock absorbing coating on said wall
4. The sport bat of claim 1, said internal chamber including: a
porous filler.
5. The sport bat of claim 1, said body being fabricated from
laminated wood
6. The sport bat of claim 5, the laminated wood being strips of
bamboo attached together with adhesive.
7. The sport bat of claim 1, said batting portion including a
plurality of chambers disposed between said taper portion and said
sweet spot
8. The sport bat of claim 2, said sleeve insert being made from
metal, graphite, or plastic.
9. A baseball bat having a longitudinal axis and a sweet spot,
including a body, including: a handle; a taper portion attached
above said handle; and a batting portion attached above said taper
portion; including. an internal chamber that decreases the weight
of said baseball bat, including: an internal space; and a wall
surrounding said internal space, including: a bottom end disposed
above said taper portion; and a top end disposed below said sweet
spot, and a distal end opposite said taper portion.
10. The baseball bat of claim 9, said body being fabricated from
laminated wood.
11. The baseball bat of claim 10, the laminated wood being strips
of bamboo attached together with adhesive.
12. The baseball bat of claim 11, said top end disposed at least
five inches from said distal end
13. The baseball bat of claim 11, said internal chamber including:
a sleeve insert in contact with said wall for reinforcing said
internal chamber.
14. The baseball bat of claim 11, said internal chamber including:
a shock absorbing coating on said wall.
15. The baseball bat of claim 11, said internal chamber including:
a porous filler.
16. The baseball bat of claim 11, said batting portion including a
plurality of internal chambers.
17. The baseball bat of claim 11, said internal space having a
total volume in the range of 2 to 6 cubic inch
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to the field of sport bats, and more
particularly to sport bats of laminated wood.
BACKGROUND OF THE INVENTION
[0002] Many sport bats, such as for baseball, softball, and
cricket, are lathe turned from a single piece of hardwood. Others
are made from aluminum. Each type of bat has drawbacks
[0003] Wood bats are not very durable They can splinter during use,
which is a safety hazard, as well as disrupting play and costing
money. The billets of wood from which the bats are made are
inconsistent and often contain hidden flaws that weaken the bat Two
bats made from the same lot of wood and with identical dimensions
can vary greatly in weight, strength, and hitting power. Sources of
good-quality wood for baseball bats are limited and the cut wood
billets must be closely inspected before acceptance by a bat maker.
The production of highest-quality bats is limited by the wood that
is available to the manufacturers
[0004] Aluminum bats are much more durable and uniform than
traditional wood bats For these reasons, aluminum bats are often
used for school play, although aluminum bats are not allowed in
major league baseball play by regulation. Another drawback of
aluminum bats is that the sound they make when hitting a baseball
is unpleasant to many people The unpleasant ringing sound is due to
persistent vibration in the bat, which also frequently causes the
player's hands to sting after a hit A major problem is the
difficulty of transitioning from an aluminum to a wood bat.
[0005] Baseball bats have been made of other materials, such as
fiber-resin composites, but most players agree that they prefer the
sound and feel of a wood bat.
[0006] Accordingly, there is a need for a wood bat that is durable
and safe, not breaking unpredictably during play. There is a need
for a bat can be made inexpensively and does not require special
wood and laborious inspection. There is further a need for a bat
with traditional sound and feel, but that has design flexibility to
allow for adapting the balance, weight, and position of the "sweet
spot" to a player's or designer's preferences.
SUMMARY OF THE INVENTION
[0007] This invention is a sport bat, such as a baseball bat,
constructed of laminated wood, preferably of laminated bamboo
strips. Bamboo is a plentiful and strong wood, typically with a
very straight grain Laminated bamboo is a wood product that is more
uniform than primal hardwood timbers and can be engineered to vary
the stiffness of the laminate as desired.
[0008] Because laminated bamboo is denser than the woods
traditionally used for sport bats, the bat of the present invention
includes one or more internal chambers to decrease the total weight
of the bat. The internal chambers are conveniently formed by
omitting certain strips of bamboo from the lay-up of the laminated
billet, according to a pre-planned lay-up schedule.
[0009] The internal chambers both decrease total weight and move
the center of gravity of the bat toward the end opposite the
handle. The preferred location of the internal chambers is below,
that is, toward the handle from, the "sweet spot." The internal
chambers also function by "enlarging the sweet spot" and dampening
vibration. The sweet spot will be discussed in more detail
below.
[0010] Each internal chamber may preferably be reinforced with a
sleeve insert, a rubbery coating on the interior wall of the
chamber, or by lightweight shock-absorbent material filling the
chamber.
[0011] The bamboo strips are laid up around the sleeve insert, if
used, to form a blank, or billet, of at least the length and
diameter of the finished baseball bat. After the adhesive used for
lamination has been cured, the billet is turned on a lathe to
produce the rough baseball bat An end cap is preferably attached to
the end of the bat and the bat is sanded and finished as
desired
[0012] The baseball bat according to the present invention has a
traditional sound and feel at impact. However, the bat of the
present invention is more durable and reliable than traditional
wood bats The bat is made inexpensively from a plentiful material
and has far more design flexibility than a one-piece wood bat. The
bat of the present invention is well-damped for vibration and does
not sting the hands of the batter.
[0013] The invention will now be described in more particular
detail with respect to the accompanying drawings in which like
reference numerals refer to like parts throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a preferred embodiment of the sport bat, shown in
longitudinal cross-sectional view
[0015] FIG. 2 is an alternative embodiment of the sport bat, shown
in longitudinal cross-sectional view and partly cut away.
[0016] FIG. 3 shows the laid-up billet from which the sport bat of
FIG. 1 will be cut.
[0017] FIG. 4 is a transverse cross-sectional view of the billet of
FIG. 3, taken along line 4-4.
DETAILED DESCRIPTION OF THE INVENTION
[0018] FIG. 1 is a preferred embodiment of the sport bat 10, such
as a softball or baseball bat 11, shown in longitudinal sectional
view An alternative embodiment of baseball bat 11, also shown in
longitudinal sectional view, is shown in FIG. 2.
[0019] Baseball bat 11 generally includes an elongate body 20 with
a longitudinal axis 21. Body 20 includes a handle 45 for gripping,
a batting portion 30, and taper portion 44 between handle 45 and
batting portion 30. Batting portion 30 is cylindrical and is for
striking a sports ball.
[0020] It is well known that striking, or hitting, a ball with a
bat typically causes vibration in the bat. The vibration can be
severe enough to sting the hands of the person batting It is also
well known that some hits do not result in vibration being felt in
the hands of the batter Such hits also tend to result in the ball
traveling especially far and fast. There are various hypotheses of
what causes this phenomenon; one especially credible explanation is
the "acoustic" theory of Rod Cross as cited by Daniel Russell.
[0021] The acoustic explanation involves the fact that a typical
ball bat has three main vibrational bending modes that are
activated when as ball is struck Cross defines the zone between the
[farthest from the handle] nodes of the first and second modes of
vibration as the "sweet zone", analogous to what is traditionally
called the "sweet spot", a point on the bat that yields strong hits
without vibration of the hands. Herein this zone will be called
sweet spot 12 Sweet spot 12 can be empirically located by
suspending the handle of the bat from the fingers and tapping the
length of batting portion 30 until the minimum of vibration is felt
in the fingers. Russell's more analytical method is to suspend a
bat with an attached accelerometer and strike the bat at many
different points. Modal analysis is done on the accelerometer data
to determine the shapes and frequencies of the various vibrational
modes.
[0022] Batting portion 30 includes one or more internal chambers 31
that decrease the weight of bat 10, shift the center of mass of bat
10, and influence the location and width of sweet spot 12 The
embodiment of FIG. 1 includes one internal chamber 31 and the
embodiment of FIG. 2 includes three internal chambers 31. It has
been found that for baseball bat 11, one or more internal chambers
31 with total volume of two to six cubic inches will reduce the
weight of baseball bat 11 to within the desired range.
[0023] It is preferred that internal chambers 31 be located between
taper portion 44 and sweet spot 12. Sweet spot 12 may be located
empirically, as discussed above, but in general, it has been found
that sweet spot 12 is five inches or less from distal end 40 of
body 20.
[0024] FIG. 3 shows the laid-up billet 53 from which the bat of
FIG. 1 will be cut FIG. 4 is a transverse cross-sectional view of
billet 53 of FIG. 3, taken along line 4-4 Dashed line 10' indicates
the outline of bat 10 that will be lathe cut from billet 53.
[0025] Billet 53 is formed from sticks 52 of bamboo or other
suitable wood. Sticks 52 are dipped into an adhesive 55, such as
epoxy, and stacked into the size and shape of billet 53 required.
Sticks 52 may be added to the assembly in a freeform manner or may
be laid into a mold, or by other techniques as are well known to
those skilled in the art
[0026] Bat 10 is preferably made from laminated wood 50, such as
laminated bamboo strips 51. Laminated bamboo 51 is a strong,
durable material, but denser than most woods used for traditional
baseball bats. To decrease the weight of bat 10, internal chamber
31 must have a density less than that of laminated wood 50 or
laminated bamboo 51
[0027] In the preferred embodiment of FIG. 1, internal chamber 31
is a simple void in laminated bamboo 51, having a wall 36 enclosing
internal space 35, which is filled with air. Wall 36 includes an
upper end 37 and a lower end 38. In the alternative embodiment of
FIG. 3, internal chamber 31 includes sleeve insert 32 to reinforce
internal chamber 31 against collapse Sleeve insert 32 may be of
metal, graphite, or plastic Although metal is denser than laminated
bamboo 51, the combination of metal sleeve insert 32 and the air of
internal space 35 has a density less than that of laminated bamboo
51.
[0028] Sleeve insert 32 may be circular, square, rectangular, or
other shape in cross section. A sleeve insert 32 that is square or
rectangular in cross section fits most snugly into a chamber 31
that is formed by omitting certain sticks 52 from the billet. A
sleeve insert 32 that is circular or other shape in cross section
should have sticks 52 that are tangent to three or more segments on
the perimeter of sleeve insert 32 such that sleeve insert 32 does
not rattle or shift within internal chamber 31 Some small voids
will likely be present between chamber wall 36 and some parts of a
sleeve insert 32 that is non-rectangular in cross section, but this
is not detrimental to the performance of bat 10.
[0029] Sleeve insert 32 is shown as a hollow pipe in the figures,
but sleeve insert 32 could alternatively be a solid piece of
graphite, plastic, or foam. The main requirement for sleeve insert
32 is that the density of the material used be low enough to
decrease the weight of baseball bat 11 to the desired total weight
and balance. It is also desirable that sleeve insert 32 absorb or
dampen shock and vibration.
[0030] Internal chamber 31 may alternatively include a rubbery
coating 34 on chamber wall 36, as shown in FIGS. 3 and 4 Rubbery
coating 34 is easily introduced during lay-up of billet 53 by
dipping one side of each of sticks 52 that enclose internal chamber
31.
[0031] In the preferred embodiment shown in FIG. 2, multiple
internal chambers 31 are filled with a porous filler 33, such as an
elastomeric foam, such as polyurethane foam, or a fibrous material,
such as jute. Porous filler 33 must have a lower density than
laminated wood 50 or laminated bamboo 51. It is desirable that
porous filler 33 absorb or dampen shock and vibration.
[0032] Although particular embodiments of the invention have been
illustrated and described, various changes may be made in the form,
composition, construction, and arrangement of the parts herein
without sacrificing, any of its advantages. Therefore, it is to be
understood that all matter herein is to be interpreted as
illustrative and not in any limiting sense, and it is intended to
cover in the appended claims such modifications as come within the
true spirit and scope of the invention.
* * * * *