U.S. patent application number 11/530441 was filed with the patent office on 2008-03-13 for two-piece ball bat with rigid connection.
This patent application is currently assigned to Nike, Inc.. Invention is credited to Mark McNamee, Christopher Page.
Application Number | 20080064538 11/530441 |
Document ID | / |
Family ID | 39158025 |
Filed Date | 2008-03-13 |
United States Patent
Application |
20080064538 |
Kind Code |
A1 |
McNamee; Mark ; et
al. |
March 13, 2008 |
TWO-PIECE BALL BAT WITH RIGID CONNECTION
Abstract
A two-piece ball bat comprising a hollow barrel attached to a
handle by a combination of mechanical interference and a layer of
rigid adhesive interposed between the interior surface of the
barrel and the exterior surface of the handle at a tapered
junction. The rigid adhesive layer prevents any direct contact
between the barrel and handle thereby eliminating the need to
provide any mating features thereon and reducing complexity and
cost of manufacture. In an alternative embodiment, glass shafting
beads are added to the rigid adhesive compound to ensure even
distribution of the adhesive compound, align the barrel and handle
and ensure separation prior to curing.
Inventors: |
McNamee; Mark; (Portland,
OR) ; Page; Christopher; (Portland, OR) |
Correspondence
Address: |
PLUMSEA LAW GROUP, LLC
10411 MOTOR CITY DRIVE, SUITE 320
BETHESDA
MD
20817
US
|
Assignee: |
Nike, Inc.
Beaverton
OR
|
Family ID: |
39158025 |
Appl. No.: |
11/530441 |
Filed: |
September 8, 2006 |
Current U.S.
Class: |
473/564 |
Current CPC
Class: |
A63B 2102/18 20151001;
A63B 2102/182 20151001; A63B 59/51 20151001; A63B 60/16 20151001;
A63B 59/50 20151001; A63B 60/08 20151001 |
Class at
Publication: |
473/564 |
International
Class: |
A63B 59/00 20060101
A63B059/00 |
Claims
1. A ball bat comprising: a hollow barrel defining a barrel
exterior surface and a barrel interior surface, said barrel having
a free distal end with an opening and a tapered joint end with an
opening; a handle defining a handle exterior surface, said handle
having a free distal end and a tapered joint end, said tapered
joint end of said handle being sized to prevent passage thereof
through the opening in said tapered joint end of said barrel
resulting in an overlapping relationship between said barrel and
said handle in a tapered junction portion; and a rigid adhesive
layer disposed between said barrel interior surface and said handle
exterior surface in said junction portion preventing direct contact
between said barrel and said handle.
2. The ball bat of claim 1, wherein said rigid adhesive comprises
glass shafting beads added thereto.
3. The ball bat of claim 1, wherein said rigid adhesive is formed
of a rigid epoxy adhesive.
4. The ball bat of claim 1, wherein said rigid adhesive is formed
of a rigid acrylic adhesive.
5. The ball bat of claim 2, wherein said rigid adhesive is formed
of a rigid epoxy adhesive.
6. The ball bat of claim 2, wherein said rigid adhesive is formed
of a rigid acrylic adhesive.
7. The ball bat of claim 1, wherein said barrel is metal and said
handle is composite.
8. The ball bat of claim 2, wherein said barrel is metal and said
handle is composite.
9. A ball bat comprising: a hollow barrel defining a smooth barrel
exterior surface and a smooth barrel interior surface, said barrel
having a free distal end with an opening and a tapered joint end
with an opening; a handle defining a smooth handle exterior
surface, said handle having a free distal end and a tapered joint
end, said tapered joint end of said handle being sized to prevent
passage thereof through the opening in said tapered joint end of
said barrel resulting in an overlapping relationship between said
barrel and said handle in a tapered junction portion; and a rigid
adhesive layer disposed between said barrel interior surface and
said handle exterior surface in said junction portion preventing
any direct contact between said barrel and said handle.
10. The ball bat of claim 7, wherein said rigid adhesive comprises
glass shafting beads added thereto
11. The ball bat of claim 7, wherein said rigid adhesive is formed
of a rigid epoxy adhesive.
12. The ball bat of claim 7, wherein said rigid adhesive is formed
of a rigid acrylic adhesive.
13. The ball bat of claim 8, wherein said rigid adhesive is formed
of a rigid epoxy adhesive.
14. The ball bat of claim 8, wherein said rigid adhesive is formed
of a rigid acrylic adhesive.
15. The ball bat of claim 9, wherein said barrel is metal and said
handle is composite.
16. The ball bat of claim 10, wherein said barrel is metal and said
handle is composite.
17. A method of making a ball bat comprising the steps of: forming
a hollow barrel defining a barrel exterior surface and a barrel
interior surface, the barrel having a free distal end with an
opening and a tapered joint end with an opening; forming a handle
defining a handle exterior surface, the handle having a free distal
end and a tapered joint end, the tapered joint end of the handle
being sized to prevent passage thereof through the opening in the
tapered joint end of the barrel; applying a rigid adhesive to at
least one of a portion of the barrel interior surface proximate the
tapered joint end or a portion of the handle exterior surface
proximate the tapered joint end; inserting the handle into the free
distal end opening of the barrel with the tapered joint end of the
handle inserted first; applying a tension force to the handle to
cause in an overlapping relationship between the barrel and the
handle in a tapered junction portion with the rigid adhesive
distributed therebetween; curing the rigid adhesive to form a rigid
adhesive layer disposed between the barrel interior surface and the
handle exterior surface in the junction portion to prevent direct
contact between the barrel and the handle.
18. The method of claim 17, further comprising the step of adding
glass shafting beads to the rigid adhesive.
19. The method of claim 18, further comprising the step of applying
a rigid adhesive to the other of a portion of the barrel interior
surface proximate the tapered joint end or a portion of the handle
exterior surface proximate the tapered joint end.
20. The method of claim 18, wherein said step of forming a barrel
employs a metal compound for the barrel, and said step of forming a
handle employs a composite for the handle.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention.
[0002] This invention relates to a ball bat having a ball bat
barrel connected to a bat handle by a combination of mechanical
interference and rigid adhesive without the barrel and handle being
in direct contact, and a method for making same.
[0003] 2. Background of the Invention.
[0004] Ball bats for baseball and softball generally have a similar
shape and comprise a handle, a barrel and a taper that smoothly
transitions between the larger circumference barrel and the smaller
circumference handle. The handle is sized for a player to easily
and securely grip the bat, and usually includes a tape or wrapping
to enhance the grip of a player's hands. The barrel is the ball
contact portion. The holding and gripping of the bat is a much
different purpose than hitting a ball, but many baseball and
softball bats are made of a single material, typically aluminum or
wood. A single material may present advantages for hitting, for
example, but be a poor material for the player's hands to hold and
grip, especially upon impact. Conversely, the single material may
present advantages for the handle region, but suffer drawbacks in
the barrel region. For example, there have been prior art ball bats
made entirely of a single composite material, but durability in the
barrel region has been a common problem.
[0005] To address some of the drawbacks of employing a single
material, ball bat makers have designed bats made of more than a
single material to provide some advantage to the players such as
enhanced performance by reducing energy loss upon impact, desired
weight and heft, desired flexibility, and shock attenuation, among
other factors. The use of two different materials for the handle
and barrel of a ball bat is generally an attempt to capitalize on
the advantageous characteristics of each material with the
recognition that a single material often means compromising or
ignoring the needs of one portion of a bat to gain optimal
performance from another portion. Ball bats in which the barrel and
handle are made of two different materials have become common on
the market. Two-piece ball bats are usually constructed of an
aluminum or aluminum alloy barrel attached to a composite handle.
The aluminum barrel provides high strength, durability and low cost
of manufacture since the raw materials are less expensive as
compared to composites, and involve less labor. Composite handles
are advantageous due to their light weight which enables the
balance of the bat to be engineered as desired, and greater
flexibility to generate more power in the swing by offering the
opportunity to customize the stiffness of the bat depending on the
player's strength and preferences. A composite handle also tends to
damp vibration more than aluminum to reduce any discomfort felt by
players when the ball is not hit squarely.
[0006] The hyphenated term "two-piece bat" as used throughout this
application is intended to refer to just the barrel and handle
combination. It is understood that the finished bat may actually
comprise more pieces such as the end caps on the barrel and handle,
but the hyphenated term refers to the barrel and handle
combination. For consistency, the present application describes the
ends of the barrel and handle with respect to the junction in the
tapered area. The barrel of a ball bat is defined as having a
distal end which is the free end at the tip of the bat, and as
having a proximate joint end which includes the taper portion that
transitions from the barrel circumference to the handle
circumference. Similarly, the handle of a ball bat is described as
having a distal end which is the free end, and as having a
proximate joint end which includes the taper portion. Therefore,
the proximate joint ends of both the barrel and handle are the
portions that are assembled together. The barrel is a hollow body
having an interior circumferential surface and an exterior
circumferential surface.
[0007] Two-piece ball bats are typically assembled by inserting the
handle into the hollow barrel through the distal end of the barrel,
and then somehow engaging a portion of the exterior surface of the
handle to a portion of the interior surface of the barrel in the
taper portions. There are two main approaches to this assembly in
the prior art. One approach is to provide some sort of mechanical
locking feature on the engaging surfaces of the barrel and handle
to join these pieces to another. An example would be to provide
exterior threads on the taper portion of the handle, and mating
interior threads on the taper portion of the barrel to form a
threaded joint. Some of these types of mechanical joints do not
require an adhesive of any sort, while some employ a combination of
mechanical joints where the barrel and handle are in direct contact
with one another and an adhesive. The other main approach is to use
an elastomer adhesive to attach the exterior surface of the handle
to the interior surface of the barrel in the tapered junction area.
An example of this type of assembly is disclosed in U.S. Pat. No.
5,593,158 to Filice et al., in which a castable urethane material
adhesively joins the handle and barrel. As most easily seen in FIG.
2 of Filice et al., the barrel and handle of Filice et al. are in
direct contact with one another in the narrower portion of the
taper area.
[0008] Mechanical joints complicate manufacture as they require
more manufacturing steps; introduce more quality control factors
for fit and finish; increase the chances of mis-assembly;
potentially increase tolerance build-up; and may require more
assembly steps to complete a ball bat. Higher complexity translates
to higher cost with respect to tooling, efficiency and labor.
[0009] There is a need for a two-piece ball bat that can be made by
simplified manufacturing processes, rapidly assembled to reduce
cost while still providing the strength and durability of a metal
bat with the advantageous strength, vibration damping and
optimization opportunities of a composite handle.
SUMMARY
[0010] The two-piece ball bat of the present invention comprises a
hollow barrel defining an exterior surface and an interior surface
with a free distal end and a tapered joint end. Both ends of the
barrel are open in order to receive a handle defining a handle
exterior surface. The handle has a free distal end and a tapered
joint end, and the tapered joint end of the handle is sized and
configured to prevent its passage through the opening in the
tapered joint end of the barrel resulting in a junction portion
between the two pieces in which they overlap. This junction portion
coincides with at least a portion of the tapered areas on both the
barrel and handle. The handle is inserted into the hollow barrel
through the barrel's free end until the tapered end of the handle
engages the tapered interior of the barrel to form the tapered
junction. A rigid adhesive is applied along the entire 360.degree.
circumference of the tapered interior surface of the barrel, or on
the outside of the tapered section of the handle or both. After the
handle is inserted, the two pieces are held in place until the
adhesive cures. In the finished bat, the rigid adhesive is disposed
in the entire circumferential tapered junction between the barrel
and handle such that the barrel and handle are not in direct
contact for any portion of their lengths.
[0011] The rigid connection between the barrel and handle of the
present invention maximizes the conservation of collision energy
upon impact with the ball to enable better performance. The
combination of the interference fit and the rigid adhesive ensures
that less of the collision energy is lost to damping as is the case
with elastomeric joints.
[0012] In another aspect of the invention, fine glass shafting
beads are added to the rigid adhesive to ensure even distribution
of the adhesive between the barrel and handle; to ensure separation
of the barrel and handle; and to align the joint by the natural
tendency of the beads to arrange themselves in a single layer when
a normal force is applied due to their spherical shape. The
adhesive with glass beads is applied to either or both the barrel
interior and the handle exterior prior to assembly. As the tapered
junction is formed by the interference fit, the glass beads ensure
even coverage of the adhesive in the joint. After curing, the
adhesive and glass beads become a composite interposed between the
barrel and the handle.
[0013] In one aspect of the invention, the barrel is made of a
metal to provide the durability and strength necessary for the ball
impact area, while the handle is made of a composite to provide
opportunities to tune the performance of the bat depending on
player's skill level and strength.
[0014] In another aspect of the invention, the barrel is made of a
composite that is engineered for durability, and the handle is made
of a different composite that is engineered for flexibility and bat
swing speed performance.
[0015] Other configurations, features and advantages of the
invention will be, or will become, apparent to one with skill in
the art upon examination of the following figures and detailed
description. It is intended that all such additional systems,
methods, features and advantages be included within this
description, be within the scope of the invention, and be protected
by the following claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention can be better understood with reference to the
following drawings and description. The components in the figures
are not necessarily to scale, emphasis instead being placed upon
illustrating the principles of the invention. Moreover, in the
figures, like reference numerals designate corresponding parts
throughout the different views. In the drawings:
[0017] FIG. 1 is a plan view of a ball bat in accordance with the
present invention.
[0018] FIG. 2 is an exploded assembly view in cross-section of the
ball bat of FIG. 1.
[0019] FIG. 3 is a perspective schematic assembly view of the
two-piece ball bat.
[0020] FIG. 4 is a detailed partial cross-section of the junction
area J shown in FIG. 1.
[0021] FIG. 5 is a schematic showing a partial cross-section of the
junction area of another embodiment of the present invention.
[0022] FIG. 6 is a detailed view of the area labeled J' in FIG.
5
[0023] FIG. 7 is a flow diagram of the method of assembly of the
two-piece bat illustrated schematically in FIGS. 5-6.
DETAILED DESCRIPTION
[0024] FIG. 1 shows assembled ball bat 10 comprising a barrel 12
and a handle 14 attached to one another at a taper junction 16.
Taper junction 16 is the transition between the larger
circumference barrel and smaller circumference handle. FIG. 2 shows
in exploded cross-section the components of the ball bat.
Specifically that barrel 12 is a hollow body with an interior
surface 18 and an exterior surface 20. Along its length barrel 12
has a distal free end 22, a taper section 24, and a proximal joint
end 26. Barrel 12 has a larger diameter at its distal free end 22
and a smaller diameter at its proximal joint end 26. Taper section
24 provides a smooth transition between these two circumferences.
Exterior surface 20 of the barrel is the ball contact surface.
Handle 14 is shown in FIG. 2 to be a hollow body, but could be
solid. Handle 14 has an exterior surface 27 and includes along its
length, proximal joint end 28, a taper section 30 and a distal free
end 32. Joint end 28 of handle 14 has the largest diameter, and
distal free end 32 has a smaller diameter. Taper section 30
transitions smoothly between the larger diameter end and the
smaller diameter end. The sizing of the distal free end is selected
to facilitate a player's grip on the bat. The fully assembled ball
bat as shown in FIG. 1 also includes barrel end cap 34 and handle
knob 36 as shown in FIG. 2 in the exploded view.
[0025] When assembled the two-piece bat comprising the barrel and
handle has an overlapping junction region where the taper sections
engage one another. The taper sections are sized to provide an
interference fit between the handle and barrel. That is, at least a
portion of taper section 24 nearest joint end 26, and at least a
portion of taper section 30 nearest joint end 28 overlap one
another and form junction region J. The dashed vertical line in
FIGS. 1 and 2 shows where joint end 28 would be disposed in the
assembled bat.
[0026] The two-piece bat comprising the barrel and handle are
assembled as shown schematically in FIG. 3. First, taper section 24
of barrel 12 and taper section 30 of handle 14 are coated with a
rigid adhesive compound A. Handle 14 is then inserted into the
opening at distal free end 22 of barrel 12 with handle distal free
end 32 inserted first. Distal free end 32 of handle 14 is pulled
through the opening at proximal joint end 26 of barrel 12 as seen
in dashed lines in FIG. 3. As the handle is pulled through the
joint end opening, handle taper region 30 will engage with barrel
taper region 24 in an interference fit. As the taper regions engage
one another, rigid adhesive A forms a rigid adhesive layer 40
between barrel interior surface 18, and handle exterior surface 27.
After the rigid adhesive A cures, rigid adhesive layer 40 prevents
direct contact between barrel 12 and handle 14 as seen in FIG. 4
which is a detailed cross-section of the region labeled J in FIG.
1. The barrel and handle are designed to engage one another by the
interference fit shown in FIG. 4 through rigid adhesive layer 40.
Since there is no direct contact between the barrel and handle,
there is no need to provide any mating features on these surfaces
thereby reducing complexity and cost of manufacture.
[0027] An alternative embodiment bat 10' of the present invention
employs a mixture of glass shafting beads in the rigid adhesive
compound. The junction area labeled J' in FIG. 5 is shown in more
detail in FIG. 6. In this embodiment, glass shafting beads 42 are
added to the rigid adhesive so that when the handle and barrel are
assembled and the adhesive cured, the resulting rigid adhesive
layer 40' is actually a composite of rigid adhesive and glass
beads. The assembly process for bat 10' is diagrammed in FIG. 7. In
step S1, the glass shafting beads 42 are added to the rigid
adhesive compound. The resulting mixture is applied to the interior
taper region of the barrel and the exterior taper region of the
handle, step S2. The handle is inserted into the barrel as shown in
FIG. 3, step S3. The handle is then pulled into engagement with the
barrel and tension force applied to center and align the junction,
step S4. The assembled barrel and handle are then held together in
place while the adhesive cures, step S5. Depending on the
properties of the adhesive employed, the curing step may take place
at ambient room temperature or encompass heat treatment. The
finished bat 10' has the junction structure shown in FIG. 6 in
which rigid adhesive layer 40' includes glass beads 42, and
prevents direct contact between the barrel and handle.
[0028] The mixture of glass shafting beads and rigid adhesive
ensures self-alignment of the barrel and handle, and even
distribution of the adhesive throughout the junction. As employed
in the manufacture of golf clubs, the glass shafting beads help to
self-center and align the joint, and ensure that the adhesive is
evenly distributed over the joining surfaces and that the joining
surfaces are separated from one another by a specific and
consistent distance as determined by the diameter of the glass
beads. Glass shafting beads are available in multiple sizes, mostly
very fine such as 0.002 inch to 0.020 inch in diameter. The
preferred range of sizes for the present invention is between 0.005
inch and 0.010 inch in diameter.
[0029] The use of rigid adhesive in the present invention, with or
without glass shafting beads, provides a rigid connection that does
not damp energy, but rather maximizes the stiffness and liveliness
of the joint. For the rigid adhesive, the preferred compounds are
epoxy or acrylic based rigid glues. In contrast, elastomer
compounds which have been used in ball bat construction serve an
isolation function. That is, they are designed to absorb and
dissipate energy, not store and return it. The rigid connection of
the present invention enhances performance by ensuring that energy
from the impact of the ball is returned to the ball instead of
dissipated in the bat. The ball bat of the present invention relies
on inherent vibration damping characteristics of the composite
material of the handle, and the engineering of that handle to
reduce sting to the player's hands when the ball is hit. As the
vibration wave travels down the barrel and into the handle, the
composite handle damps vibration along its entire length to provide
comfort to a player's hands. This is a particularly effective
approach given that the ball to bat collision is so brief and
instantaneous. This collision is largely a local event and occurs
so quickly that before the vibration or sting reaches a player's
hands, the ball has been hit. The composite handle enables the
damping to occur closer to the player's hands so that any damping
action takes place after the bat as returned the maximum amount of
collision energy to the ball and the ball is no longer in contact
with the bat.
[0030] The barrel of the present invention is preferably made of an
aluminum alloy for durability and strength. It is also possible
that a resin with carbon and/or glass fiber composite could be
engineered to have similar durability, strength and hardness
characteristics as a metal barrel. Such an engineered material for
the barrel is within the purview of the present invention, and in
this application is referred to as being metal-like. The handle is
preferably a composite of curable resin impregnated with carbon and
glass fibers which is amenable to tuning and engineering for
desired performance characteristics. This engineering is simply a
way to tune the conversion of potential energy into kinetic energy
when a ball is hit. Potential energy is stored when the ball and
bat undergo a physical deformation at collision. That energy is
converted to kinetic energy as the ball and bat return to their
respective original shapes and the stored energy is released into
the energy of the ball's movement away from the bat. With prior art
wooden bats, the ball undergoes more deformation upon impact. With
an aluminum or composite barrel, the bat is able to store and
release a portion of the potential energy of impact. The composite
handle enables the bat designer to change the degree of flexibility
in the handle portion to maximize bat speed and strength. A handle
portion with optimized flexibility based on the swing speed of the
player will enable the bat to return more of the energy of the
player's swing to the ball by strong swing energy in the form of
handle flex and releasing it by straightening at the moment of
impact. Depending on the strength of the player, it may be better
to stiffen or increase the flexibility of the handle, and composite
enables that type of tuning.
[0031] The ball bat of the present invention having a rigid
connection between the barrel and handle employing a combination of
mechanical interference and a rigid adhesive that prevents direct
contact between the barrel and handle results in enhanced
performance with reduced complexity and cost of manufacture.
Eliminating direct contact between the barrel and handle at the
junction eliminates the need to provide any mating features which
also eliminates costly manufacturing steps and enables assembly to
be greatly simplified. The composite handle provides opportunities
to engineer the bat for optimum performance without sacrificing the
durability and strength of a metal or metal-like barrel.
Interposing a layer of rigid adhesive between the barrel and handle
results in a rigid joint that maximizes the distance the ball will
travel by ensuring that as much energy from the impact is returned
to the ball.
[0032] While various embodiments of the invention have been
described, it will be apparent to those of ordinary skill in the
art that may more embodiments and implementations are possible that
are within the scope of the invention.
* * * * *