U.S. patent number RE32,394 [Application Number 06/760,474] was granted by the patent office on 1987-04-14 for sole construction for shoes.
This patent grant is currently assigned to Patoflex Corporation. Invention is credited to Johann Ehrlich.
United States Patent |
RE32,394 |
Ehrlich |
April 14, 1987 |
Sole construction for shoes
Abstract
A sole construction for shoes is disclosed which includes at
least two independently prefabricated wooden parts which are
interconnected by at least one foamed polyurethane intermediate
part. The interfacing surfaces between the wooden parts and the
intermediate part are substantially free from sharp edges and the
upper portions of the interfacing surfaces taper gradually
arcuately upwardly and outwardly to the marginal areas thereof
adjacent the surface supporting the sole of the wearer's foot, said
marginal areas terminating in tangential relation with the latter
surface without forming a step therewith.
Inventors: |
Ehrlich; Johann
(Krems/Weinzierl, AT) |
Assignee: |
Patoflex Corporation
(Scottsdale, AZ)
|
Family
ID: |
3585781 |
Appl.
No.: |
06/760,474 |
Filed: |
July 30, 1985 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
191066 |
Sep 26, 1980 |
04400894 |
Aug 30, 1983 |
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Foreign Application Priority Data
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Sep 28, 1979 [AT] |
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6382/79 |
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Current U.S.
Class: |
36/33; 36/31;
36/86 |
Current CPC
Class: |
A43B
13/08 (20130101); A43B 13/141 (20130101) |
Current International
Class: |
A43B
13/08 (20060101); A43B 13/02 (20060101); A43B
13/14 (20060101); A43B 013/08 (); A43B
013/14 () |
Field of
Search: |
;36/33,86,13,31,11.5
;12/146B |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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13152 |
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Mar 1881 |
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DE2 |
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888860 |
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Sep 1943 |
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FR |
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909922 |
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Jan 1946 |
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FR |
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358308 |
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Apr 1938 |
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IT |
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586696 |
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Dec 1958 |
|
IT |
|
76315 |
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May 1918 |
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CH |
|
79788 |
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May 1919 |
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CH |
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Primary Examiner: Kee Chi; James
Attorney, Agent or Firm: Salter & Michaelson
Claims
What is claimed is:
1. A sole construction for shoes, comprising at least two
.[.independently.]. prefabricated parts formed of a wood material,
said wood parts being interconnected to each other at an area that
is located beneath the ball of the foot of the wearer by at least
one flexible intermediate part that consists of foamed
polyurethane, said intermediate part including a first outer
portion located adjacent to the sole of the wearer's foot, a second
outer portion located adjacent to the walking surface of said sole
and a middle neck portion disposed beneath said first and second
outer portions, the width of said intermediate part as measured in
the longitudinal direction of said sole being greater at the
marginal areas of said first and second outer portions than at the
smallest width of said middle neck portion, the interfacing
surfaces between said wood parts and said intermediate part being
free from sharp edges, the upper portions of said interfacing
surfaces tapering gradually arcuately upwardly and outwardly from
said middle portion to the marginal areas of said first and second
outer portions, and the portions of said interfacing surfaces in
the marginal areas adjacent to the surface supporting the sole of
the wearer's foot each being tangent to said latter surface without
forming a step therewith.
2. A sole construction as claimed in claim 1, the interfacing
surfaces between said wood parts and the intermediate part in the
marginal area adjacent to the walking surface being tangent to the
surface of said wood parts adjacent to the walking surface.
3. A sole construction as claimed in claim 1, the surface adjacent
to the sole of the wearer's foot being uncovered.
4. A sole construction as claimed in claim 1, said intermediate
part being symmetrically shaped relative to the vertical axis
thereof, and extending essentially perpendicular relative to the
walking surface and also extending essentially in the longitudinal
direction of the sole.
5. A sole construction as claimed in claim 4, protrusions extending
from the middle area of said intermediate part essentially in a
longitudinal direction of the sole and from opposite sides of said
intermediate part, said protrusions being formed integral with said
intermediate part.
6. A sole construction as claimed in claim 5, said protrusions
being formed with undercuts at the outer ends thereof.
7. A sole construction as claimed in claim 6, the surfaces of said
protrusions being connected to the middle area of the intermediate
part and defining rounded surfaces therewith.
8. A sole construction as claimed in claim 1, said intermediate
part being located parallel to the walking surface which is formed
in an arcuate shape.
9. A sole construction as claimed in claim 8, said walking sole
being formed integral with said intermediate part.
Description
The present invention refers to a sole of wood for shoes and
consisting of prefabricated or pre-shaped wooden parts being
connected with one another at the area of the ball of the foot by
flexible intermediate parts consisting of foamed polyurethane.
Soles of wood are already known and have many advantages. Such
wooden soles are hard or rigid at the heel portion, at the area of
the joint and at the area of the shoe tip and thus are supporting
the foot in an orthopaedically favourable manner. If wooden soles
are for orthopaedic reasons provided with a foot bed, then the
soles comprise in addition a heel vault, a support for the inner
joint, a support for the outer joint, a support for the middle
portion of the foot, a depression for the ball of the foot and, if
desired, also a toe barrier, noting that all these portions must
also have a certain strength and stability, which requirement is
fulfilled with wooden soles at any rate. Further, wood has the
property to insulate against coldness, to act temperature
controlling and to absorb humidity so that shoe soles consisting of
wood are hygienic and comfortable to wear. Known soles consisting
as a whole of wood have, however, the drawback to be stiff at the
area of the ball of the foot and thus to represent a hindrance for
the rolling motion of the foot on walking so that such stiffness
can under certain circumstances be detrimental to health. For these
reasons soles were proposed which consist of two wooden parts which
are connected with one another at the area of the ball of the foot
by a flexible intermediate part. Thus, the sole becomes flexible at
the area of the ball of the foot and suitable to follow the rolling
motion of the foot on walking.
It has particularly been proposed to make the flexible intermediate
part of foamed polyurethane. When using such a material for the
intermediate part, a reliable and strong connection between the
intermediate part and the wooden part is achieved without
additional measures. The polyurethane is formed of two components,
i.e. a polyol compound on the basis of polyesters or polyethers and
isocyanates, comprising at least two NCO-groups which react with
the hydroxy groups (OH-groups) of the wood or with other compounds
contained in the wood and comprising active hydrogen atoms, so that
a strong chemical bond can reliably be established between wood and
polyurethane.
In addition, also a mechanical bond is achieved in view of the
polyurethane foam penetrating during its formation into the pores
of the wood, so that also for this reason the polyurethane is
inseparably bonded to the wood. Furthermore such soles can be
rapidly produced in a simple manner by introducing the individual
wooden parts into a mold and filling the remaining space or cavity
with the polyurethane-forming agent.
It has now been found that known soles consisting of wooden parts
mutually connected by polyurethane do not meet all requirements. If
such soles are strongly bent at the area of the ball of the foot
there exists the danger that the marginal areas of the intermediate
part located adjacent the sole of the foot on the one hand and
adjacent the walking surface on the other hand are too strongly
elongated or too strongly compressed. If the intermediate part is
too strongly elongated, i.e. if the specific elongation is too
great, there exists the risk of cracks or fractures being formed at
the area of transition between the intermediate part and the wooden
parts. If there is too strong a compression, the intermediate part
becomes vaulted in outward direction which gives the wearer of the
shoe an uncomfortable feeling. Too strong a compression results, in
addition, in the danger of pinching of the foot sole of the wearer
of the shoe between both wooden parts in case the width of the
intermediate part as measured in longitudinal direction of the sole
is small at the marginal portion adjacent the foot sole and thus
the edges of said both wooden parts connected by the intermediate
part are strongly approaching when bending the sole.
The present invention has as an object to avoid the mentioned
drawbacks and to further improve a shoe sole comprising an
intermediate part consisting of polyurethane. For this purpose, the
invention essentially consists in that the width of the
intermediate part or intermediate parts, respectively, is, as
measured in longitudinal direction of the sole, greater at the
marginal area adjacent the sole of the foot and at the marginal
area adjacent the walking surface of the sole than in the middle
area located therebetween. By increasing the width at the marginal
areas there results the advantage that on bending the sole at the
area of the ball of the foot the specific elongation and the
specific compression becomes substantially reduced and that,
therefore, the mentioned drawbacks can not arise. In addition, such
construction results in a greater connecting surface between
intermediate part and wooden parts as compared with a construction
having intermediate parts of equal width at any place, so that a
still better mechanical and chemical bond between the wooden parts
and the intermediate part of polyurethane is reliably achieved.
According to a preferred embodiment of the invention, both marginal
portions of the intermediate part or the intermediate parts,
respectively, are rounded at the area of transition to the middle
area. Thus, sharp edges are avoided in which on bending great
tension stresses and compression stresses, which could result in
destroying the intermediate parts at this area, are avoided, and
intermediate parts of such construction undercut the
correspondingly shaped wooden parts at the marginal area adjacent
the sole of the foot as well as at the marginal area adjacent the
walking surface of the shoe sole, so that the bonding between the
wooden parts and the intermediate parts is still further improved
and the desired bending of the sole within the area of the ball of
the foot on walking is reliably established for enhancing the
wearers comfort and for avoiding effects detrimental to health
which are inherent for wooden soles having an overall
stiffness.
Preferably, the marginal portions of the intermediate part or the
intermediate parts are tangent to the sole surface so that no steps
are formed at the area of transition which steps would be
disturbing to the wearer of the shoe particularly if such steps
would contact the foot sole of the wearer. The thickness of the
intermediate parts, as measured in a direction perpendicular to the
surface contacting the foot sole, is with such an embodiment
gradually increasing from zero up to a value equal to the total
thickness of the sole, so that a smooth transition between
non-yielding wooden parts and yielding intermediate parts is
achieved and even on load stress of the yielding intermediate part
no distrubing steps occur between wooden parts and intermediate
parts.
According to a preferred ebodiment of the invention the
intermediate part or the intermediate parts, respectively, is,
respectively, are symmetrically shaped relative to a middle axis
extending essentially perpendicular relative to the walking surface
and preferably also relative to an axis extending in perpendicular
direction relative to this middle axis and essentially in direction
of the longitudinal direction of the sole. Thus, all bending
stresses exerted are equally distributed over the individual parts
and any injury of these intermediate parts on such bending stress
is reliably prevented.
Particularly with strongly stressed soles simultaneously forming
the insole and/or the foot bed it is of advantage if, according to
a further feature of the invention, protrusions are protruding from
both sides of the middle area of the intermediate part or the
intermediate parts, respectively, essentially in longitudinal
direction of the sole and being integral with the intermediate
part. Such protrusions still further increase the connecting
surface between both wooden parts and the intermediate part and
still further improve the chemical bond. In such a construction,
the mechanical bond can be made still more reliable by providing
the protrusions at their free ends with undercuts, for example by
giving the protrusions a dove-tail end. For avoiding local peak
stresses, it is convenient that the protrusions have a rounded area
of transition to the middle area of the intermediate part or the
intermediate parts, respectively.
With the known embodiment one single intermediate part of
polyurethane is provided for mutually connecting two wooden parts.
In such an embodiment, the intermediate part must on bending of the
sole take up the total stress so that this intermediate part is
excessively stressed. In view of providing one single intermediate
part and thus localizing the bending motion to one single area, the
upper connected to the sole is on bending equally strongly loaded
at one single area so that it becomes necessary to spare gussets in
the upper at the connecting area with the sole which can be already
disturbing in shoes or sandals having a free toe portion or heel
portion. Wooden soles comprising flexible intermediate parts can,
however, also be used in connection with closed shoes having
neither a free toe portion nor a free heel portion. In a closed
shoe any interruption in the upper, said interruption having the
shape of a recess, a cut-out portion or a gusset, could at any rate
not be realized. Therefore and according to the invention more than
two wooden parts are provided and connected with one another by
intermediate parts arranged within the ball area of the foot
thereby distributing bending motion of the sole over a plurality of
intermediate parts. In this case, the intermediate parts can be
narrower as one single intermediate part, noting that the bending
stress is distributed over a plurality of intermediate parts and
over a greater area, respectively, and, with this embodiment, it is
not required to spare gussets in the upper at the area of the
intermediate parts.
The intermediate parts can extend along a straight line as seen in
a cross section parallel to the walking surface. It is, however,
convenient to provide intermediate parts which are arcuate as seen
in a section parallel to the walking surface, thereby adapting in
an orthopaedically more favourable manner the bending motion of the
sole on walking.
The invention also provides the possibility to integrally form the
walking sole together with the intermediate part, thus not only
simplifying production operation but also providing an additional
bonding link between the wooden parts by the walking sole.
It is already known to produce a sole comprising an intermediate
part of polyurethane by introducing the wooden parts into a mold
and by introducing in the free space of the mold a
polyurethane-forming material which is allowed to foam within the
mold closed. A sole produced in such a manner does, however, not
show completely plane surfaces free of steps because it is
impossible to produce the wooden parts with sufficient accuracy
and, therefore, the polyurethane will overflow or flow out. It has
shown that one can never adapt the wooden parts relative to the
mold such that a sole with plane outer surfaces will result. The
technical reason therefor are the inherent properties of the wood
and the always ununiform shaping operation even when using machines
of the most modern type. Therefore and according to the invention,
at least the surface facing the foot sole and the side surfaces of
the sole are, after removal of the sole from the mold, mechanically
worked, preferably by grinding or milling, such that these surfaces
are completely without steps and show no disturbing elevations.
According to a preferred embodiment of the process according to the
invention, the polyurethane-forming material is filled into the
mold prior to closing this mold so that the sole can be produced in
a simple manner without expensive equipment.
As already mentioned, a chemical reaction between the NCO-groups
present in the isocyanate and the OH-groups of the wood and the
other compounds comprising active hydrogen atoms is taking place
when producing a sole according to the invention so that a
particularly strong and permanent chemical bond is obtained between
the wooden parts and the intermediate parts. It has now been found
that for this reaction the water content of the wooden parts, to
which the intermediate part is to be applied, is of extreme
importance. If the humidity content is too great, the chemical
reaction proceeds too rapidly and the polyurethane foam has during
its period of formation no time for penetrating the pores of the
wood so that the strength of the mechanical bond between the wooden
parts and the intermediate parts becomes reduced. Furthermore, high
amount of carbon dioxide is produced during the progressing
reaction, what has as a result that the intermediate parts have a
very coarse foam structure at the connecting areas between the
wooden parts and the intermediate parts what again contributes to
an increase of the danger of fracture within this area. According
to a further feature of the inventive process, the humidity content
of the wooden parts is less than 12 percent, preferably less than 6
percent, prior to introducing same into the mold. A bond of
particularly high strength can be obtained between the wooden parts
and the intermediate parts if, according to the invention, the
humidity content of the wooden parts is between 0.01 and 5 percent.
In this case, the reaction between the hydroxy groups present in
the wood and the other compounds containing active hydrogen atoms
and equally present in wood and the NCO-groups contained in the
isocyanate of the polyurethane-forming material is taking place in
a particularly advantageous manner, so that not only a mechanical
bond between the wooden parts and the intermediate parts of
polyurethane is reliably achieved by the polyurethane penetrating
the pores of the wood but also a particularly strong chemical bond
is guaranteed.
A sole according to the invention can be an insole over which the
upper of the shoe is lasted and on which subsequently an
intermediate sole together with a walking sole or only a walking
sole is fixed or can be a sole which is simultaneously forming the
insole and/or the foot bed and to which the upper is laterally
fixed. Such a wooden sole is, as a rule, provided with a walking
sole. If the walking sole is integral with the intermediate part,
the walking sole can be applied in a rapid and simple manner in
view of the possibility to form this walking sole simultaneously
with the production of the intermediate part and, in addition, the
walking sole provides an additional bond between the wooden parts.
Furthermore, the walking sole is reliably bonded to the wooden
parts and any loosening of the walking sole can reliably be
prevented and this particularly within the area of the ball of the
foot where are arranged the intermediate parts and where the
bending motion is taking place. Such an embodiment further makes
sure that the walking sole has no steps whatsoever even within the
area of the intermediate parts and no final machining is required
when simultaneously producing the whole walking sole together with
the intermediate parts. Simultaneous production of walking sole and
intermediate parts, for which purpose polyurethane of walking sole
quality must naturally be used, can, however, be effected only if
the wooden parts have a humidity content of less than 12 percent,
preferably less than 6 percent, because polyurethane of walking
sole quality has a higher specific weight and gives the mentioned
chemical reaction in a satisfying manner only if the wood has a
humidity content within the mentioned range.
The invention is schematically illustrated in the drawing showing
embodiments of the invention.
FIG. 1 shows a sole according to the invention and to be used as
insole over which the upper is lasted in a section extending in
longitudinal direction of the sole and
FIG. 2 shows a sole according to the invention and simultaneously
forming the insole and/or the foot bed.
The sole shown in the drawing consists of two wooden parts 1,2
connected one with the other by an intermediate part 3 consisting
of polyurethane and being arranged in the area of the ball of the
foot. The surface 4 of the sole is to be contacted by the foot sole
of the wearer of a shoe provided with such a sole and the surface 5
of the sole is facing in direction to the walking surface. In the
embodiment illustrated by FIG. 1, in which the sole is used as
insole, the surface 5 is connected with an intermediate sole not
shown and, if desired, with a walking sole. In the embodiment shown
in FIG. 2, the surface 5 is immediately carrying the walking sole
6, which, in this case, is preferably integral with the
intermediate part 3.
The intermediate part 3 is symmetrically shaped relative to a
middle axis 7 extending essentially perpendicular to the walking
surface as well as relative to an axis 8 extending essentially
perpendicular relative to this middle axis. The width B at the
marginal areas of the intermediate part 3, i.e. at the areas
eadjacent the surfaces 4 and 5 of the sole is greater than the
smallest width b at the middle area located therebetween. As is
clearly shown in the drawing, both marginal areas pass to the
middle area in a rounded fashion and are tangent to the surfaces 4,
5 of the sole.
In the embodiment shown in FIG. 2, protrusions 9 are protruding
from the middle area of the intermediate part 3, said protrusions
protruding from both sides of the intermediate part 3 essentially
in longitudinal direction of the sole and being integral with the
intermediate part 3. The protrusions 9 are shown as having a
ball-like enlargement at the ends but can have, however, also a
dove-tail shape.
Further, the drawing shows a sole consisting of two wooden parts
being mutually connected by one single intermediate part. A
plurality of individual parts can, however, be provided at the area
of the ball of the foot thus, however, also increasing the number
of wooden parts to be connected by the intermediate parts. Wooden
parts located between adjacent intermediate parts can be made very
narrow because all intermediate parts must be provided within the
area of the ball of the foot.
A sole according to the invention is produced by introducing the
wooden parts into a mold and filling the remaining free space of
the mold with a polyurethane-forming material. The
polyurethane-forming material can be poured into the mold prior to
closing the mold or after closing the mold. It is also possible to
inject the polyurethane-forming material after closing the mold. In
each case, the intermediate parts of polyurethane are given their
shape as well as are unseparably bonded to the wooden parts, noting
that in connection with the embodiment shown in FIG. 2 the walking
sole 6 is simultaneously applied in its final shape. The sole
removed from the mold is subsequently ground on the surface facing
the foot sole so that this surface has neither disturbing
elevations nor disturbing depressions.
Of course, also other embodiments of the shoe sole than those shown
in the drawing are within the scope of the present invention.
* * * * *