U.S. patent application number 13/311922 was filed with the patent office on 2012-06-07 for filament wound u-shaped support units for footwear.
This patent application is currently assigned to JKM TECHNOLOGIES, LLC. Invention is credited to D. Casey Kerrigan.
Application Number | 20120138216 13/311922 |
Document ID | / |
Family ID | 46161116 |
Filed Date | 2012-06-07 |
United States Patent
Application |
20120138216 |
Kind Code |
A1 |
Kerrigan; D. Casey |
June 7, 2012 |
Filament Wound U-Shaped Support Units for Footwear
Abstract
A method is described for manufacturing a U-shaped support unit
for use in footwear. A shaft mandrel has a longitudinal axis and a
cross-section with at least one U-shape region. An enclosed shape
of composite material is formed over the shaft mandrel which
includes one or more layers of resin-impregnated reinforcing
fibers. One or more cuts are made through the enclosed shape to
create U-shaped support units adapted for use as a weight bearing
structure in footwear.
Inventors: |
Kerrigan; D. Casey;
(Charlottesville, VA) |
Assignee: |
JKM TECHNOLOGIES, LLC
Charlottesville
VA
|
Family ID: |
46161116 |
Appl. No.: |
13/311922 |
Filed: |
December 6, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61420545 |
Dec 7, 2010 |
|
|
|
Current U.S.
Class: |
156/189 |
Current CPC
Class: |
B29C 70/32 20130101;
B29C 53/821 20130101; B29C 61/006 20130101; B29C 2793/00 20130101;
B29L 2031/504 20130101; B29C 53/8075 20130101; B29C 53/564
20130101 |
Class at
Publication: |
156/189 |
International
Class: |
A43D 29/00 20060101
A43D029/00 |
Claims
1. A method for manufacturing a U-shaped support unit for use in
footwear, the method comprising: providing a shaft mandrel having a
longitudinal axis and a cross-section with at least one U-shape
region; forming an enclosed shape of composite material over the
shaft mandrel, the composite material including one or more layers
of resin-impregnated reinforcing fibers; cutting through the
enclosed shape of composite material to create U-shaped support
units adapted for use as a weight bearing structure in
footwear.
2. A method according to claim 1, wherein forming the enclosed
shape includes using an automatic filament winding machine to wind
reinforcing fibers around the shaft mandrel.
3. A method according to claim 2, wherein winding the reinforcing
fibers includes rotating the shaft mandrel about its longitudinal
axis.
4. A method according to claim 1, further comprising: incorporating
the U-shaped support units into footwear as compliant weight
bearing structures.
5. A method according to claim 1, wherein the reinforcing fibers
are impregnated with resin by use of a resin impregnating system
prior to being formed on the shaft mandrel.
6. A method according to claim 1, wherein the reinforcing fibers
are impregnated with resin by resin injection after being formed on
the shaft mandrel.
7. A method according to claim 1, wherein forming the enclosed
shape includes pressing an outer molding surface over at least a
portion of the composite material to form an outer surface of the
enclosed shape.
8. A method according to claim 1, wherein forming the enclosed
shape includes curing the composite material of the enclosed shape
for a period of time prior to cutting.
9. A method according to claim 1, wherein the composite material is
cured for a period of time after cutting.
10. A method according to claim 1, wherein forming the enclosed
shape includes placing a non-fiber structural member onto the shaft
mandrel which becomes incorporated into the composite material.
Description
[0001] This application claims priority from U.S. Provisional
Patent Application 61/420,545, filed Dec. 7, 2010, which is
incorporated herein by reference.
TECHNICAL FIELD
[0002] The invention relates to footwear construction and more
specifically, to construction of a U-shaped filament-reinforced
composite unit for use in a midsole or sole of footwear.
BACKGROUND ART
[0003] Existing conventional shoe cushioning can interfere with
natural biomechanics and muscle function and may compromise
long-term musculoskeletal health. Typical footwear cushioning
mechanisms including foam, gel, and coil spring devices that absorb
shock at initial impact (foot strike), adversely affect
proprioceptive input required for healthy muscle tuning throughout
the body. As such, this conventional cushioning arrangement can
compromise bone health and can predispose the wearer to
musculoskeletal injury.
[0004] Joint forces in the gait cycle are well-observed to be at
their maximum at the moment of peak body weight force, which does
not occur at foot strike but later in mid-stance. For walking, that
is during loading response and at terminal stance, and for running
that is during mid-stance. Typical footwear cushioning compresses
at foot strike, absorbing shock at initial impact, but the
cushioning does not measurably compress and release (or comply) in
time with the rise and fall of the peak body weight force when
joint forces are at their peak.
[0005] There is a need for footwear that effectively reduces
musculoskeletal wear and tear, especially useful for helping
prevent knee and hip osteoarthritis as well as other common
musculoskeletal injuries. Such footwear would include a midsole
that incorporated a compliant structure able to compress and
release in harmony with the rise and fall of the body weight force
during weight bearing activities such as gait--without cushioning
the shock at initial impact. Such footwear would compress and
release only when the joint forces are at their maximum, thereby
minimizing joint forces.
[0006] FIG. 1 A-C shows top, cross-sectional and bottom views of
one specific example of a U-shaped support unit 101 for use in
footwear which is made of a filament-reinforced composite material.
As used herein, the term "U-shaped" is used broadly as a generic
descriptor of any structure with a U-, V- or C-shape etc. The
U-shaped support unit 101 includes an upper foot support arm 102
substantially parallel to the foot supporting surface of the
footwear, and a lower ground arm 103 substantially parallel to the
ground contacting surface of the footwear. The foot support arm 102
and the ground arm 103 are connected together at a medial side base
106, while the lateral ends 104 and 105 of each arm are free to
displace under force towards the center axis 107. The U-shaped
support unit 101 is placed inside the midsole or sole of a shoe to
provide a spring-like compliant shoe interface along a definite
path that flexes, i.e., compresses and releases in time with the
rise and fall of the body weight force without absorbing impact
shock. Such a U-shaped support unit for footwear is described more
fully in U.S. Pat. No. 7,418,790, which is incorporated herein by
reference.
[0007] To best support the body weight, such a U-shaped footwear
unit ideally is made of filament-reinforced composite material. The
typical manufacturing processes for such materials in footwear,
however, are insufficient, inconsistent, and/or not cost-effective.
Injection molding of filament-reinforced material provides an
automated consistent product, but it requires shortened fiber
lengths that in composite form do not provide the combined
stiffness and durability needed to completely suspend the body
during gait. Hand lay-up of filament-reinforced composite materials
can offer sufficient stiffness to support the body weight, but it
requires substantial human labor, is prone to consistency errors,
and is not cost-effective for use in footwear manufacturing.
SUMMARY
[0008] Embodiments of the present invention are directed to a
method for manufacturing a U-shaped support unit for use in
footwear. A shaft mandrel has a longitudinal axis and a
cross-section with at least one U-shape region. An enclosed shape
of composite material is formed over the shaft mandrel which
includes one or more layers of resin-impregnated reinforcing
fibers. One or more cuts are made through the enclosed shape to
create at least one open U-shaped section of fiber-reinforced
composite material, and the U-shaped section is then separated into
U-shaped support units adapted for use as a weight bearing
structure in footwear.
[0009] The enclosed shape may be formed using an automatic filament
winding machine to wind reinforcing fibers around the shaft
mandrel, for example, by rotating the shaft mandrel about its
longitudinal axis. The enclosed shape may be formed by pressing an
outer molding surface over at least a portion of the composite
material to form an outer surface of the enclosed shape. The
enclosed shape may also be formed over a non-fiber structural
member that is pre-placed onto the shaft mandrel and which is
incorporated into the composite material.
[0010] The reinforcing fibers may be impregnated with resin by use
of a resin impregnating system such as a resin wetting bath, spray
or brush prior to being formed on the shaft mandrel, or by resin
injection after being formed on the shaft mandrel. The composite
material of the enclosed shape may undergo a curing period of time
prior to after cutting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 A-C shows top, cross-sectional and bottom views of a
filament-reinforced composite material U-shaped support unit for
use in footwear.
[0012] FIG. 2 is a perspective view of a type of a shaft mandrel
for use in an embodiment of the present invention.
[0013] FIG. 3 A-C shows cross-sectional views of three different
symmetry types of shaft mandrels.
[0014] FIG. 4 A-B shows cross-sectional views of two U-shaped shaft
mandrels with a non-fiber structural member placed onto the shaft
mandrel that becomes included into the composite material of the
final cured U-shaped support unit.
[0015] FIG. 5 A-B shows cross-sectional views of two embodiments of
compression molds that are placed over the composite material and
shaft mandrel after the filament winding process.
DETAILED DESCRIPTION
[0016] Embodiments of the present invention include an automated
filament winding process that enables consistent and cost-effective
manufacturing of a U-shaped compliant unit for use in a footwear
sole or midsole that compresses and releases at the time when the
body weight and joint forces are at their greatest so as to
minimize the peak joint forces. The use of a filament winding
process provides an automated and repeatable process for the
manufacturing of reinforced composite materials. Fibers are wound
around the shaft mandrel which rotates along its longitudinal
axis.
[0017] FIG. 2. is a perspective view of a shaft mandrel 201
according to one specific embodiment of the present invention. The
shaft mandrel 201 has a longitudinal axis and a U-shape
cross-section as seen in FIG. 3A over which an enclosed shape of
composite material is formed from one or more layers of
resin-impregnated reinforcing fibers. Support rods 202 along the
longitudinal axis of the shaft mandrel 201 can be inserted into
receiver collars of a filament winding machine which rotates the
shaft mandrel 201 along its longitudinal axis. As the shaft mandrel
201 rotates, filament material is wound around it to form multiple
layers of composite material. One or multiple tows of fiber of any
thickness may be wound over the mandrel at a given time. The
positioning, orientations and thickness of the tows are the same as
for procedures already known in the art and their selection does
not form part of the present invention.
[0018] In one embodiment, the filament can be drawn through a resin
impregnating system to impregnate it with resin before being wound
around the shaft mandrel 201. In other embodiments, the filament
may be pre-impregnated with resin or resin may be injected into dry
filament after winding. There may be a period of time for curing of
the resin at any convenient point in the process to cure the
composite material according to known operable methods appropriate
to the particular resin fiber composite. For example, the assembly
may be heated in a standard or platen press oven. A variety of
reinforcing fiber types, either natural or synthetic, or a
combination thereof may be used. Similarly, a variety of resin type
materials may be used such as epoxy, polyurethane, polyester or
vinyl ester. The resin may be thermosetting or thermoplastic and
may include additional fillers or substrates that provide improved
physical qualities to the resultant composite unit.
[0019] After the enclosed shape of composite material is formed
over the outer surface of the shaft mandrel 201, it is cut into
multiple final U-shaped elements for incorporation into footwear.
In one embodiment, the composite material is cut directly into the
final U-shape support units while still on the mandrel 201. For
example, the composite material can be cut off the mandrel 201
using a device such as a water jet saw that cuts through the
composite material but not the mandrel 201. Or cutting blades can
be incorporated into a female mold such that when the female mold
is compressed onto the mandrel 201 the blades cut through the
composite material. Alternatively, the enclosed shape can be cut
along the axial length on cut line 301 so as to create two
symmetric U-shaped section lengths of fiber-reinforced composite
material. This cutting creates one or more long open U-shaped
section elements which can be removed from the mandrel 201 and then
cut into multiple final U-shape elements for incorporation into
footwear. Or, the composite material may be pulled off an end of
the mandrel 201 in whole and then cut into the final U-shape
support units. The final U-shape support units are placed in the
midsole or sole of a shoe such that one of the arms of the unit
lays parallel to the foot support surface and the other arm lays
parallel to the ground contact surface.
[0020] Filament winding is typically used for manufacturing
filament-reinforced structures with axial symmetry and closed
cross-sectional shapes such as pipes, high pressure containers and
rocket motors. But embodiments of the present invention can include
a filament winding process which uses a shaft mandrel that is not
symmetric along its axis. FIG. 3B illustrates an embodiments of a
shaft mandrel 201 having an asymmetric cross-section that results
in two asymmetric U-shaped sections after cutting of the composite
material. FIG. 3C shows an example of a shaft mandrel 201 suitable
for producing a single U-shaped section after cutting along cut
line 301. All the embodiments shown have a consistent cross-section
along their longitudinal lengths, but that is not necessarily
required in all embodiments.
[0021] FIG. 4 A-B shows cross-sectional views of two embodiments of
U-shaped mandrels 201 that have been altered in shape at the end
vertices to accommodate a non-fiber structural member 401 that is
pre-placed onto the mandrel 201 prior to filament winding. The
additional structural member 401 becomes integrally incorporated
into the filament wound composite material such that the final
U-shape support unit includes both the composite material and the
additional structure. In another embodiment, a material such as
fabric or a semi-rigid or rigid structure can be placed over the
outer surface of the entire mandrel or a portion thereof prior to
filament winding to form a base layer of the final U-shape support
unit.
[0022] FIG. 5 A-B illustrates two embodiments of the present
invention wherein a compacting molding surface 501 is placed over a
portion (FIG. 5A) or the entire surface (FIG. 5B) of the enclosed
shape of filament-reinforced composite material 502 during the
curing process. In the embodiment shown in FIG. 5A, a clamping
device such as a vise or a press compresses opposing plates that
form the molding surface 501 on either side of the outer surface of
the composite material 502. In the embodiment in FIG. 5B, an
enclosing mold forms the molding surface 501 that completely
encompasses the composite material 502. In another embodiment, a
material such as cello shrink tape can be applied to compress the
composite material 502 against the mandrel 201 and this tape can
either be left on or removed after the curing process. The molding
surface 501 can be removed sometime during or after full curing of
the resin.
[0023] Although various exemplary embodiments of the invention have
been disclosed, it should be apparent to those skilled in the art
that various changes and modifications can be made which will
achieve some of the advantages of the invention without departing
from the true scope of the invention.
* * * * *