U.S. patent application number 13/351943 was filed with the patent office on 2013-07-18 for cushioning device with ventilation.
This patent application is currently assigned to SKYSOLE CORPORATION. The applicant listed for this patent is Jerome Gross, Joseph Skaja. Invention is credited to Jerome Gross, Joseph Skaja.
Application Number | 20130180023 13/351943 |
Document ID | / |
Family ID | 48750154 |
Filed Date | 2013-07-18 |
United States Patent
Application |
20130180023 |
Kind Code |
A1 |
Gross; Jerome ; et
al. |
July 18, 2013 |
CUSHIONING DEVICE WITH VENTILATION
Abstract
An insole for a shoe is characterized by a cushioning device
that circulates air between a plastic bottom layer and a soft,
porous upper layer. The air is directed to designated areas of the
insole via vertical apertures, which circulate air to and over the
foot of a user. The bottom layer is formed with air capturing
structures that when collapsed expel air that is forced through the
apertures and to the surface of the user's foot. The bottom layer
and the upper layer are separated by a porous middle layer that may
be foam or other light weight but breathable material.
Inventors: |
Gross; Jerome; (Hermosa
Beach, CA) ; Skaja; Joseph; (Hermosa Beach,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gross; Jerome
Skaja; Joseph |
Hermosa Beach
Hermosa Beach |
CA
CA |
US
US |
|
|
Assignee: |
SKYSOLE CORPORATION
Hermosa Beach
CA
|
Family ID: |
48750154 |
Appl. No.: |
13/351943 |
Filed: |
January 17, 2012 |
Current U.S.
Class: |
2/22 ; 12/146R;
2/455 |
Current CPC
Class: |
A43B 17/02 20130101;
A43B 17/14 20130101; A43B 1/0045 20130101; B29D 35/142 20130101;
A43B 17/023 20130101; A43B 17/08 20130101; A43B 17/006
20130101 |
Class at
Publication: |
2/22 ; 2/455;
12/146.R |
International
Class: |
A41D 13/06 20060101
A41D013/06; A43D 11/00 20060101 A43D011/00; A41D 13/015 20060101
A41D013/015 |
Claims
1. A multi-layer cushioning device adapted to conform to a human
body part comprising: a bottom layer formed of a material selected
from plastic and thermoset, the bottom layer having a lower surface
including a plurality of uniformly spaced apart dome shaped
structures extending substantially a length and a width of the
lower surface; a middle layer on top of the bottom layer; and a top
layer having a plurality of vertical apertures that extend through
the middle layer and through the bottom layer.
2. The multi-layer cushioning device of claim 1 further comprising
an upwardly extending lateral protrusion, the upwardly extending
lateral protrusion comprising column-shaped vertical recesses on an
outer surface for communicating air thereinthrough.
3. The multi-layer cushioning device of claim 2 wherein an upper
edge of the lateral protrusion is an arc.
4. The multi-layer cushioning device of claim 1 wherein the middle
layer comprises a foam.
5. The multi-layer cushioning device of claim 1 wherein the middle
layer comprises air.
6. The multi-layer cushioning device of claim 1 wherein the bottom
layer is adhered to the top layer with a thermally activated
adhesive.
7. The multi-layer cushioning device of claim 1, wherein the dome
shaped structures are inverted.
8. The multi-layer cushioning device of claim 1, wherein the device
is shaped to the contour of a human foot.
9. The multi-layer cushioning device of claim 1, wherein the dome
shaped structures are resilient and return to an original shape
once compressed.
10. The multi-layer cushioning device of claim 1 further comprising
a lip extending around a periphery thereof.
11. The multi-layer cushioning device of claim 1, wherein the dome
shaped structures are selected to collapse when stepped upon,
expelling air away from the bottom layer.
12. The multi-layer cushioning device of claim 1, wherein the dome
shaped structures extend approximately one half way into the middle
layer.
13. The multi-layer cushioning device of claim 1, wherein the
bottom layer is a plastic mesh.
14. The multi-layer cushioning device of claim 1 further including
a non-stretch moderator adjacent to the bottom layer.
15. The multi-layer cushioning device of claim 1, further
comprising a deodorizing material dispersed when the dome-shaped
structures are compressed.
16. The multi-layer cushioning device of claim 1, wherein the
cushioning device can be individually tuned by adjusting the size,
shape, and thickness of the dome shaped structures.
17. The multi-layer cushioning device of claim 1, wherein at least
one layer includes chitin.
18. A method for fabricating a shoe insert comprising: fabricating
a bottom layer from a plastic material that is formed into a
negative mold of the insert; heating an interfacing layer and
placing the interfacing layer over the bottom layer while the
bottom layer is still heated from the molding operation; applying
an adhesive to a plurality of attachment points to create an
instant and permanent bond between the plastic bottom layer and the
interfacing layer; and applying air pressure to the interfacing
layer to bond it to the plastic bottom layer.
19. The method for fabricating a shoe insert of claim 18, wherein
the plastic bottom layer is formed by selecting a sheet of plastic
material and securing the sheet into a clamping frame, and then
placing the clamping frame and sheet in a temperature controlled
oven until a melting point is reached, whereupon the sheet of
material is placed in a negative mold and cured.
20. The method for fabricating a shoe insert of claim 19, further
comprising adding a foam layer between the bottom layer and the
interfacing layer comprising: heating a foam material and then
positioning the foam material over the plastic bottom layer;
lowering the interfacing layer onto a negative mold containing the
bottom layer and the foam material; pressing the interfacing layer
to the bottom layer at attachment points to trap the foam material
therebetween using air pressure; and pressing an edge of the foam
material into the bottom layer while the bottom layer is in a
melted state.
Description
BACKGROUND
[0001] The present invention relates to foot wear, and more
particularly to a novel insole for insertion into a shoe, or other
cushioning applications, that provides padding and forced
ventilation using a unique multi-layer layer composition.
[0002] There is a wide variety of shoe inserts and pads on the
market today that are intended to be placed inside a shoe for the
purpose of providing comfort to the foot. It has long been known
that shoe inserts and pads can provide a softening mechanism to
absorb the shock as the foot bears the weight of the user, and the
result of this shock absorbing function provides many
orthopedic-related beneficial results. By way of example, the
following references provide background into the current art of
shoe insert devices.
[0003] Huiskamp, U.S. Pat. No. 1,605,588, discloses a sole of a
shoe with a pneumatic cushion captured between a lower sole and an
upper surface. The pneumatic cushion extends between the ball and
the toe, and the device further includes perforations that compress
when the wearer walks, to pump up the sole for a softer and gentler
sole.
[0004] Brahm, U.S. Pat. No. 2,474,815, discloses an air circulating
insole for a shoe that vents air to the toe area by drawing in air
at the heal and using discharge valves. It has cutouts in a middle
layer to locate air passageways that travel in a longitudinal
direction. Thus, air is drawn in at the back of the shoe and forced
out through the front of the shoe. Air holes are placed around the
toe area to give the pressurized air an escape route.
[0005] Burnham, U.S. Pat. No. 3,225,463, discloses another air
ventilated insole, including a compressible chamber in the heel
portion and an exhaust valve directed toward the toes. The chamber
acts as a pump to drive air out of the valve and across the surface
of the foot. Outlet holes are placed around and between the toes to
carry the air to the toe area before leaving the shoe.
[0006] Sandmeier, U.S. Pat. No. 4,215,492, discloses an insole for
a shoe that provides an air flow pattern over the foot. The insole
includes dimples that massage the foot, and have two layers that
are separated by a spacer to create a gap therebetween. The upper
layer has an air inlet that lets air into the gap, and as the user
walks the air is forced toward the toe area where openings are
located that vent the air. As the pressure is relieved, the air
once again fills the gap in a repetitive manner.
[0007] Sessa, U.S. Pat. No. 5,400,526, discloses a tri-layer
footwear sole that has a continuous bottom surface, and a middle
layer that forms air pockets or bulb with the bottom layer. The top
layer had vertical air channels leading from the air pockets to the
upper surface, where the air can contact the foot. Air is drawn
into the sole at the back of the insert by the heel, and forced
upward across the foot.
[0008] Cintron, U.S. Pat. No. 5,675,914, discloses a removable
footbed insert with a single volume structure at the heel, formed
in a molded lower layer and further including a foam upper layer.
The layers have perforations that serve as air channels, and the
volume structure acts as a bellows that drives air through all
three layers.
[0009] Cheng, U.S. Pat. No. 6,041,519, discloses a plurality of
dome shaped structures that are used to drive air forward to the
toe area through designated channels. The air is driven forward and
the insert makes use of channels to direct the air to the toe
area.
[0010] Ahlbaumer, U.S. Pat. No. 7,617,618, teaches an insert that
has an aerating function that pumps air through the insert via an
elastically deformable dome-shaped arch that maintains contact with
the wearer's arch for comfort. Air is driven through apertures in
the insert as the dome fills with air and then is compressed by the
foot.
[0011] Skaja et al., U.S. Pat. No. 7,178,267 discloses a footwear
structure where two material layers are overlaid such that the two
material layers are in contact with one another. The two material
layers are heated to a forming temperature and are then
vacuum-formed together to form a composite material layer in a
three-dimensional form of the footwear structure. The sole assembly
includes a first material layer made of a plastic, and a second
material layer attached to the first material layer.
[0012] As can be seen from the foregoing, the prior art is
plentiful with inserts that cushion or breathe with the action of
walking. However, the mechanism by which air is forced through the
insert is typically originated at the heel using a large bladder or
baffle, which pushes air forward along the insert using channels of
some sort. This has obvious disadvantages, including malfunction if
the bellows mechanism fails and also that the insert must be
designed to accommodate this single, large air receptacle. Further,
to fill such a cavity quickly requires a vent that can easily get
clogged, rendering the entire device ineffective. In reality, most
of these bellows systems are complex and cannot distribute air
throughout the insole. These devices are complex and require a
great deal of assembly. Along with prohibitive labor costs, the
complexity of these mechanisms also results in high defect rates in
manufacturing as well as at the consumer level. Thus there has been
virtually no commercial success with this approach. Thus, the art
is in need of a shoe insert that is not reliant on a single bellows
in the aft of the insert, and will be more reliable while providing
better comfort to the wearer.
SUMMARY OF THE INVENTION
[0013] A multi-layer cushioning device adapted to conform to a
human body part includes a bottom layer formed of a plastic
material, the bottom layer having a lower surface including a
plurality of uniformly spaced apart dome shaped structures (normal
or inverted) extending substantially a length and a width of the
lower surface. The cushioning device further comprises a porous
middle layer on top of the bottom layer, which can be gas, foam, or
other shock absorbing material. A top layer is also provided that
has a plurality of vertical apertures that extend from the top
layer through the middle layer and down to the bottom layer,
providing a multitude of airways between the top and bottom layers.
In a preferred embodiment, the cushioning device also includes an
upwardly extending lateral protrusion that serves as an arch
support, where the upwardly extending lateral protrusion includes
column-shaped vertical recesses on an outer surface for
communicating air thereinthrough.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1a is a side view of a first embodiment of the present
invention;
[0015] FIG. 1b is an opposite side view of the embodiment of FIG.
1a;
[0016] FIG. 2 is a top view of the embodiment of FIG. 1a;
[0017] FIG. 3 is a bottom view of the embodiment of FIG. 1a;
[0018] FIG. 4a is a cross sectional view of the embodiment of FIG.
2 taken along lines 4a-4a; and
[0019] FIG. 4b is a cross sectional view of the embodiment of FIG.
2 taken along lines 4b-4b.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] A first embodiment of the present invention is shown in
FIGS. 1-4. An insert 10 is characterized by a cushioning device
that circulates air between an bottom layer 12 and an upper layer
14. The air is directed to designated areas of the insert 10 via
apertures 16, which circulate air to and over the foot of a user.
The bottom layer 12 and the upper layer 14 are separated by an air
layer 18, or alternatively the middle layer can be a foam or other
light weight but breathable material. The insert is shaped to
contour to a human foot and fit snugly inside a shoe, although
other cushioning embodiments such as gloves, knee pads, and the
like could also be incorporated into the present invention. The
bottom surface 20 of the insert 10 includes a multitude of
deformable geometries, such as inverted, dome shaped elements 22
generally uniformly spaced across the bottom surface as shown in
FIG. 3. The dome shaped structures 22, which can serve as tack
points to connect the adjacent layers, are designed to collapse
under the pressure of a user when weight is applied, as when a step
is taken, forcing air to escape the dome shaped structure and
circulate within the shoe and around the bottom layer. Some of this
air is forced through apertures 16 that extend vertically between
the bottom layer 12 and the top layer 14 to expel the air below the
bottom of the foot. The dome shaped structures 22 therefore not
only cushion the foot by absorbing some of the energy from the
downward pressure of the foot in its weight bearing capacity, but
also provide a forced air stream around and vertically through the
insert at designated locations.
[0021] The insert is preferably formed with laterally extending
protrusion or wing 26 that extends upward from the bottom surface
12 so as to contour to the arch of a user. The wing's upper surface
is smooth, and its lower surface 26b is characterized by
column-shaped recesses 28 that extend substantially the height of
the wing 26. The top of the wing 26 forms an arc 32 that may
vertically extend slightly above the height of the heel 34. The
column-shaped recesses 28 serve two purposes, namely they add
rigidity to the insert 10 while providing vertically channels along
the outside of the insert for air to move from the bottom surface
to the top surface. These channels or recesses help to circulate
the air inside the shoe as the user walks and compresses the dome
shaped structure 22. The periphery of the insert 10 may include a
lip 30 that extends around the insert. The lip 30 can help position
the insert 10 inside the shoe and prevent shifting of the insert,
and can also form a semi-seal with the inner surface of the shoe to
force more air through the vertical apertures 16 extending between
the lower 12 and upper 14 surfaces.
[0022] The cross section of the insert 10 is shown in FIGS. 4a and
4b, showing the top surface and bottom surface separated by an
intermediate layer preferably of air 18. In an alternate
embodiment, the air layer 18 is replaced with a soft, permeable
foam or other lightweight breathable material. The dome-shaped
structures 22 extend generally the length and width of the bottom
surface and extend roughly half way between the lower surface 12
and the upper surface 18 into the foam material 18. Each dome
shaped structure has an arch profile uniformly spaced from adjacent
profiles. Similarly, the vertical apertures 16 are uniformly spaced
apart (but could alternatively be irregularly spaced for various
functional or cosmetic objectives), and extend from the bottom
surface 12 to the top surface 14, providing channels by which air
can pass from the bottom of the insert to the top of the insert.
When weight is applied to the insert, as would occur when a user
takes a step, the dome-shaped structures 22 collapse under the
weight of the user's foot, forcing air trapped in the cavity of the
dome-shaped structure 22 to be expelled along the bottom surface of
the insert. The shape, thickness, and material properties of the
domes are selected to collapse at a predetermined rate so as to
control the flow of air through the insole. Some of this expelled
air will flow around the insert, aided by the vertical
column-shaped recesses 28 which channels air up the side of the
insert and over the foot. Air will also be forced through the
vertical apertures 16, which are preferably concentrated over the
ball of the foot and under the arch, and in the area of the toes.
Air passing through the insert via the vertical apertures cool the
foot and ventilate the insert, helping to prevent moisture from
collecting in the shoe. When the user lifts his or her foot, the
resilient dome-shaped structures 22 immediately return to their
nominal shape and condition, ready to conduct the cycle again of
collapsing and reforming with each step to continuously cool and
ventilate the shoe. In this manner, air is constantly circulated
from the top of the insert to the bottom of the insert and vice
versa, which helps to prevent moisture build up and helps to cool
the foot.
[0023] It is to be understood that other shapes could serve the
function of the dome shaped structures 22, such as cones, blocks,
and volumes of various shapes and sizes, inverted or non-inverted,
and still operate within the scope of the present invention. No
intention is implied that any particular shape or configuration is
limiting in any manner with respect to the descriptions or
depictions in the drawings.
[0024] The insert 10 is created in such a manner that there is an
airspace or foam 18 between the upper layer 14 and the bottom layer
12. The bottom layer is preferably fabricated from a plastic
material that is formed into a negative mold of the insert. In the
case of an airspace between the layers, once the plastic bottom
layer is formed, and while still in a heated condition, the
interfacing upper layer is heated to a forming temperature and
placed over the bottom layer. Pressure is then applied to the
composite structure so that it forms and contacts the attachment
points of the plastic bottom layer 12. In a preferred embodiment,
an adhesive is applied to the attachment points to create an
instant and permanent bond between the plastic bottom layer and the
interfacing upper layer.
[0025] To fabricate the plastic bottom layer 12, a sheet of
material is loaded into a clamping frame. The frame is closed to
secure the edges of the sheet and reliably hold it during the
process. The clamp frame with the sheet is placed in a highly
temperature controlled oven, preferably in between 2 ovens for
optimum heat saturation of the material. When the material reaches
its melt point, it is then lowered over a mold with either male or
female features. As with all components of this process there are
multiple ways to accomplish each aspect of it. For instance,
instead of moving the hot sheet of material, the oven can be moved
and the mold can take its place, without moving the material. Next,
a vacuum is applied, pulling the material tightly to the mold
surface. The mold is kept at a stable temperature at 60 degrees
Celsius, which is significantly lower than traditional melt
temperatures which can be up to 180 degrees Celsius, leading to a
quicker cool down period to cure the material. Fans directed at the
molded part are also turned on to hasten the curing. The clamp
frame then pulls the molded part off the mold or the mold is
lowered to accomplish the same. The molded insert bottom layer is
then removed from the machine and the process repeated. This can
all be completed in less than 10 seconds. For this insert, the
cycle can be in the 60 second range. Multiple insoles can be
thermoformed at the same time using the proper molds and
clamps.
[0026] By adding a simultaneous forming operation, a foam layer 18
may be added to the insole 10. The foam 18 (such as ethyl vinyl
acetate) is heated and then positioned over the plastic cushioning
layer 12. This plastic layer 12 is left in the female mold so that
all contact points are reinforced by the mold. A top mold is
lowered onto the female forming mold, thus trapping and sealing off
the foam layer 18. The heated foam layer 18 with a heat activated
adhesive or hot melt is then pressed to designated attachment
points by accurately applied air pressure. At the same time, the
edge of the foam layer 18 is pressed tightly to the plastic
cushioning layer. This process securely and consistently attaches
the foam layer 18 to the bottom plastic layer 12 very accurately
and allows manipulation of the intervening space between the lower
and upper layers. This simultaneous molding of the foam layer
eliminates the pre-molding foam operation and equipment. It also
cuts the total process time in half, and reduces the need for
precision matched tooling that is needed without this process.
[0027] The use of controlled air pressure to attach the 2 or more
materials allows for complex tack points to be managed. This keeps
the cushioning geometries fully functional and allows accurate
control of the air space between layers. It is very difficult and
expensive to align pressing equipment to accomplish the same. If
there is any misalignment or material thickness variation at all,
the result can be a defective part.
[0028] Plastic meshes can also be used as the lower layer 12. These
meshes are breathable materials that can be thermoformed into any
shape by installing a vacuum barrier in the forming machine. This
barrier is preferably a silicone sheet which traps the mesh between
itself and the vacuum, thus pulling the mesh into the mold surface.
All the other process remains the same. The present inventors are
unaware of any other process that can produce parts with the level
of porosity available using this method. Injection molding, for
example, can mold mesh, but only on a relatively flat surface and
the cost is prohibitive for any product that requires multiple
molds such as footwear.
[0029] The above-described process greatly reduces mold costs that
are typical for footwear products. The low pressure molds are
generally made of aluminum, and require no match mold sets. The
cost of these molds is less than half the cost of typical
compression molds and 80-90% less than injection molds. The cycle
time of this process is many times faster than typical compression
mold cycles of footwear products so that multiple molds are not
required to meet manufacturing objectives further reducing mold
costs. In the case of the simultaneous foam molding operation, an
entire set of molds and molding equipment is eliminated.
[0030] The bottom layer, because of its shape retention properties,
is preferably an elastomer with high recovery properties and very
high physical properties. Plastic or thermoplastic urethane (TPU)
has a combination of properties, including process properties
relative to thermoforming that work well with the above-described
process and product, such as excellent "hot strength" and a very
short "forming window." These two properties are important because
it allows the insole to be demolded quickly and stretched over mold
features and undercuts during demolding. It then snaps back to the
formed shape with no ill effects. This feature dramatically reduces
mold costs versus injection and can make shapes that other
processes cannot make at commercially viable prices. The TPU
material is extruded into the desired sheet dimensions. A suitable
thickness for this insole is 0.5 mm, with the width and length
relative to the thermoforming machine requirements. The sheet can
be fed into the thermoforming machine in rolls or in sheets. Other
materials are suitable, such as block amids, polyesters, eva,
olefin, tpo, tpe, thermoset materials, and others. Foams and layers
of material can also be used in this process. TPU, however, has an
optimum combination of process and physical properties as well as a
relatively low cost. It is also over engineered for human use, so
it is a safe material to use for most applications without a great
deal of testing.
[0031] There are three basic thermoforming machine types that can
be used to process the present invention.
[0032] A) Cut Sheet Shuttle. This equipment utilizes sheets of
material that have been cut to an appropriate size. The material is
then shuttled between the ovens and the mold. Conversely, the
material can stay in one position and then the ovens and mold are
over or under the material. This machine is more economical and
simpler than other equipment. It is also easier to control material
waste with this equipment. Process flexibility is also very high.
Cycle time potential, and therefore output is limited, however. As
with all types of thermoforming equipment, computer controlled
ovens and machine movements are desirable to control product
consistency and production efficiency.
[0033] Rotary Thermoforming. This equipment moves the material in a
circle, as it passes through the oven(s), then to molding and to
demolding stations. It allows for more operations in a smaller
space. Operations such as insert loading or pre-heating the
material are easily done with this equipment. Even multiple molding
stations or simultaneous molding of multiple materials can be
accomplished. Due to better access and more space, semi or even
full automation is possible. Top and bottom molds and other devices
can be operated independently so that various layers and inserts
can be managed in one machine in a simultaneous or sequential
manner with minimal cycle time loss.
[0034] In-line Roll Fed. This equipment uses rolls of material that
pass over the ovens, then over the mold, cooling and then die
cutting, while still in a roll format. Even the waste material is
automatically rolled up after die cutting. It is then recycled back
into the material. The advantage of this equipment is speed. Cycle
times as fast as ten seconds are common. Even the material
extrusion process can be integrated with this equipment,
drastically reducing the cost of raw material. The capital cost of
this equipment is higher than other types and there is much more
set up and process restriction.
[0035] By inserting various materials and objects, sophisticated
products can be made with one single process. Decorative or
functional fabrics and meshes can be in-molded into the insole or
other products. Design and color detail, logos, functional elements
can also be in-molded. This is due to the relatively low pressure
and quick material curing involved in thermoforming. The material
being molded is not subject to high pressures that other processes
require. This results in inserts that are gently fused to the
melted material with only moderate pressure. Thus, the insert is
not distorted or deformed. TPU in particular freezes consistently
and quickly around an insert, cleanly framing it so that it appears
to be attached by a hand process.
[0036] In addition, reinforcing inserts of almost any material can
be added to the product during the thermoforming process. By using
heat activated adhesives or hotmelt adhesives, the inserts are
securely attached. In some cases, no adhesives are necessary.
Complete layers of material can be inserted for various functional
and decorative objectives. Inserts can be made in a number of ways,
but they are preferably made by the same thermoforming process and
equipment. This is a very efficient way to manufacture the inserts
and it tends to lower their costs because of the unique ability of
thermoforming machines to mold very thin parts. This also optimizes
over head of the forming equipment and factory. A myriad of other
types of inserts designed to enhance the finished product can be
added as well during the manufacturing process. Issues of comfort,
traction, bacteria control, conductivity, design, decoration,
branding, perception, temperature control, functional adjustment
and many other finishing details can be addressed via in-mold
insertion.
[0037] Virtually any design or graphic can be pre or post applied
to the materials. Textures can be applied to the forming molds and
or the materials. Most plastic materials can be extruded
transparently, so that decoration can be added to either side or
both sides, yielding very desirable decoration. Paints and
transfers can be also be applied to the mold prior to forming so
that the plastic picks up the material. The molds and or material
can also be texturized. By applying air pressure to the top of the
material as it is being thermoformed, the mold texture and detail
will transfer to the material at a very high level.
[0038] Male molds can also be used to form the present invention.
Male molds have the advantage of the availability of severe
undercuts in the finished part. These are not readily available
with other molding techniques. "Undercuts" combined with materials
such as TPU, open the door to product features not possible
previously. Cushioning elements aligned precisely to impacts on
contoured objects such as body parts can be inexpensively made this
way. Another advantage of males molds is that an entire layer of
plastic can be molded over an insert or layer. This makes the
surface of the finished product tougher and protects the
insert.
[0039] Because the thermoforming process does not require match
mold sets and because materials such as TPU have tremendous hot
strength, shapes and parts that previously could not be demolded
are easily demolded. Moreover, because the thermoforming process
carries heat with the finished part, secondary and undesirable
adhesion operations can be eliminated. Adhesives that activate only
when heated to specific temperatures are well suited for attaching
the layers of the present invention. Adhesive application is then
limited to the sheets of material prior to thermoforming. This
operation can be highly controlled and automated and toxic releases
and direct human exposure eliminated.
[0040] Supplemental components can be attached to the thermoformed
insert by simply placing them into the forming mold and then
forming the plastic sheet over them. In most cases a heat activated
adhesive must first be applied to the component to that it bonds to
the plastic sheet during forming. The same can be done in a female
mold, but in this case the component would not be overmolded but
simply attached to the plastic sheet.
[0041] As noted above, a second material can be simultaneously
molded and attached to the plastic sheet. This is a useful feature
in making the plastic more comfortable and perceptually acceptable
for consumers. A foam or fabric layer is important as a skin
interface. The technique of using pressure to attached the two
materials is important in assembling a finished product. Otherwise,
a matched set of tools, and very accurate material dimensions are
required, thus driving up the cost of the finished product and the
reject rate. This would make the finished product far too expensive
and not viable. This is particularly true of more contoured
products such as helmets, protective gear and other products that
are contoured to fit various areas of the body.
[0042] In addition to those materials discussed above, the insole
may also include a non-stretch material that acts like a moderator,
such as a non-woven polyester fabric, which can better distribute
the impact load. This moderator can also prevent the bottom layer
from compacting around the dome-shaped structures. The moderator
can be added to any layer, but is located adjacent the bottom
layer. The insole can also be specially tuned or adjusted to a
particular user by judicious selection of the dome shape, size, and
thickness, to control pronation, weight distribution, comfort, and
other factors. Further, in addition to distributing air throughout
the insole, other dispersals such as deodorant, sanitizer, and the
like can also be distributed across the insole. This component has
become beneficial in assembling the eva to the thermoplastic domes
without the domes showing through the top of the insole.
[0043] Another material that can be used for the skin or upper
layer is Chitin, a material that shares some properties with
cellulose and is soft, biocompatible, can inhibit bacteria growth
and is easily dyed to create colorful patterns on the top of the
insole.
[0044] Another assembly option is to form each layer of material
separately, coating them with heat activated adhesives and then
aligning them together. The assembly is then inserted into a mold
and heated. Pressure is then exerted on the top layer to compress
all layers together. Tack points can be used to attach the
materials only where desired. Individual layers or the entire
product can be post perforated for breathability or perceptual
objectives.
[0045] It has further been discovered that the multi-layer
cushioning device of the present invention can be stacked or
layered to increase the functional cushioning, particularly in
other applications. Using multiple cushioning devices in a stacked
or nested arrangement can dramatically increase the overall
cushioning capability, and provides a low cost alternative to other
materials that are far more complex and expensive.
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