Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SANDWICH-TYPE FOOTWEAR STIFFENING ELEMENT OF RIGID OR AT LEAST
SEMI-RIGID BEHAVIOUR, USABLE AS PART OF THE SOLE UNIT OR INSOLE
This invention relates to a footwear element of rigid or semi-
rigid behaviour, in accordance with the introduction to the main
claim.
As is well known, for certain footwear, and in particular sports
footwear, the sole unit must behave rigidly or at least semi-
rigidly. This is for example the case in mountain shoes or boots,
cycle shoes and boots for roller skates (both of traditional type
and with in-line wheels), or in footwear used for certain
athletics specialities. This sole unit behaviour is required in
order to achieve better foot support and/or to enable the user or
athlete to transfer the greatest possible force to the ground or
to the vehicle on which he moves (for example a bicycle), in order
to achieve improved performance.
Usually, to achieve a greater or lesser rigidity of the sole unit
(traditionally of leather or rubber, or of rubber and/or synthetic
polymer mixtures), two different methods are used, namely by
inserting into the shoe vamp an insole constructed of more rigid
materials than those used for the sole unit, such as wood,
leather, cellulose conglomerates (such as that known by the
commercial name of Texon), or of synthetic polyurethane resins,
polypropylene, nylon or the like, or by metal blade or bar
inserts; or by using rigid materials for the sole unit itself,
such as leather, wood or synthetic resins of the aforesaid type.
The first method (insole) is used for example for mountain shoes
or boots, and the second method for example for clogs.
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These solutions only partly achieve the desired object, ie they
achieve only a limited sole or insole rigidity.
Footwear has recently appeared on the market having the sole unit
or insole (and in particular the whole or part of the sole unit)
constructed of composite materials combining fabrics or fibres of
light materials having a high elastic modulus (such as carbon,
aramid, glass or synthetic resin fibres) embedded in a resin
acting as a binder. Such solutions and constructional methods
result in components (soles or insoles) having a considerable
rigidity/weight ratio, making them advantageous over components
obtained by the two aforesaid methods. However these components
have a higher cost than that achieved by the other said known
methods. This derives from the high cost of certain fibres (such
as carbon fibres) and of the production process, which is usually
slower and more delicate than those involved in the production of
components constructed only of synthetic resins or by the other
aforesaid known methods,
An object of this invention is to provide a footwear element of
rigid or semi-rigid behaviour for use in footwear as a sole unit
or part of the sole unit or as an insole which, although providing
the footwear with the required rigidity, is of very low
constructional cost.
This and further objects which will be apparent to the expert of
the art are attained by a footwear element in accordance with the
characterising part of the main claim.
The invention will be more apparent from the accompanying drawing,
which is provided by way of non-limiting example and on which:
Figure 1 is an exploded view of a mountain boot provided with the
element of the invention;
Figure 2 is a section on the line 2-2 of Figure 1;
Figure 3 is a cross-section through a cycling shoe provided with
the element of the invention;
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Figure 4 is an exploded view of a different embodiment of the
invention;
Figure 5 is a perspective view of a further embodiment of the
invention;
Figures 6A, 6B, 6C are sections through that portion of the
element of the invention indicated by K in Figure 4;
Figures 7A, 7B, 7C are sections on the line 7-7 of Figure 4
showing different forms of the element of the invention;
Figure 8 shows a further embodiment of the invention;
Figures 8A, 8B and 8C are sections on the lines 8A-8A, 8B-8B and
8C-8C of Figure 8 respectively;
Figure 9 shows a further variant of the invention; and
Figures 9A, 98 and 9C are sections on the lines 9A-9A, 9B-9B and
9C-9C of Figure 9 respectively.
Said figures show an element 1 for footwear such as a mountain
boot 2 or a cycle shoe 3) said element being arranged to stiffen a
lower part 4 of said footwear) which comprises a vamp 7 associated
with said part 4. In one embodiment of the footwear, shown in
Figures 1 and 2, this lower part 4 comprises a sole unit 8 of
rubber or similar material, on which the rigid or semi-rigid
element 1 is positioned and fixed to act as an insole. Between
the element 1 and sole unit 8 there can be provided a damping
intersole 9 of expanded polyurethane or expanded ethylvinylacetate
(EVA). On the element 1 there is placed a usual removable
anatomic insole 10. Consequently in these figures, the element 1
stiffens the part 4, and is fixed to the sole a nit by gluing or
the 1 i ke.
In contrast, in Figure 3 the element 1 acts as the actual sole
unit, and is joined to the vamp in the usual manner, for example
by gluing. The removable insole 10 is placed on the element 1 as
in the footwear embodiment of Figures 1 and 2, added pieces of
rubber 11 (or other like material) possibly being applied
externally to the lower side of said element and fixed to this
element in known manner, for example by gluing.
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The element 1 is of layered type and comprises (see Figures 6A, 68
and 6C) three layers mutually superposed to form a one-piece
sandwich. The outer layers 13 and 14 are of a material having
greater rigidity than the inner layer 15, the thickness of this
latter being however greater than the individual layers 13 and 14.
Preferably the layers 13 and 14 (connected together laterally) at
the edges or side walls 26 and 27 of the element 1, so as to
enclose the layer 15 within them), are constructed of the same
material, and in particular of artificial plastic or synthetic
resin, or of nylon, polyurethane or polypropylene, or of composite
material comprising synthetic resins and fabrics or fibres of
carbon aramid) glass or other synthetic resins. The layer 15,
acting as the core of the layered structure 1A of the element 1,
is constructed of a lighter material than the constituent material
of the layers 13 and 14, such as artificial plastic foam or
expanded resin (shown in Figure 6C), cellular materials of natural
origin (such as light wood, shown in Figure 6A)) or cavity-
containing materials (Figure 68) formed from touching cylindrical
plastic elements i7 of equal or different circular cross-sections
or of elliptical or polygonal cross-sections. The elements 17 can
be solid or hollow and define a honeycomb structure.
As stated, the various layers 13, 14 and 15 are joined together to
form a one-piece structure 1A which cannot be separated into its
various components. The various components (layers) of the
structure 1A are integrated in various ways: for example by
polymerizing the epoxy resin with which the layers 13 and 14 have
been preimpregnated) if thermoplastic materials are used; by
softening the resin defining the core (Figure 6C) until fusion) if
thermoplastic materials are used for the layers 13 and 14; or by
gluing the various layers together, this method being suitable
whether the layers 13 and 14 are of thermosetting or thermoplastic
materials.
A stiffening element 1 obtained in accordance with the invention
is of lower cost than a known equal-thickness similar element
obtained from composite materials, however its rigidity is
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comparable to these. The element 1 is very light in weight
compared with analogous known elements, while having at least a
comparable rigidity to these layer. It is preferably used along
the entire extent of the lower part 4 of the footwear 2 or 3 (ie
along the entire foot of the user) and can comprise a plurality of
portions of constant or variable cross-section 20, 21, 22 (Figure
but again in layer form) with different flexibilities on the
basis of their position relative to the user's foot (for example
with greater flexibility at the forefoot). This different
flexibility can also be obtained by constructing the element 1 in
one piece (but again of layer form) with different thicknesses,
decreasing towards the front end 23 of the element 1 {with
reference to the foot shape of the user wearing the footwear 2 or
3), as shown in Figures 4 and 5. Alternatively, the thickness of
the element 1 can be greater in the forefoot portion or region 20
and decrease towards the heel region 22, or be constant along its
entire longitudinal axis A, as shown in Figure 1. Furthermore)
the cross-section of the element i can be constant (Figure 7A),
variable (Figure 7B) and decreasing towards its lateral edges 26
and 27, or comprise ribs 28 (Figure 7C) for further stiffening.
Alternatively, to achieve differential rigidity for the element 1)
it can comprise differently ribbed portions (as in the embodiment
of Figure 8 to 8C). For example the front portion or forefoot 20
can comprise at least one pair of lower parallel ribs 33, with no
ribs on the arch portion, and with the heel or ankle portion 22
comprising only one central rib 34.
In a further variant of the invention (see Figures 9 to 9C), at
least the lower part (with reference to the figures under
examination) can be clad with a film 36 of thermoplastic material
(such as that known by the commercial name of FEBAX) able to
protect that element. As shown in Figure 9, the film 36 can also
cover at least a portion of the upper part of the insert, in its
forefoot region 20, and in that case also wrap the lateral part of
the corresponding element 1 (see Figure 9A). This film is
associated with the element 1 for example during the
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polymerization of the aforedescribed resin, or otherwise during
the assembly (moulding) of the various portions of said element.
During this stage, a layer 44 of fibrous material, such as felt or
non-woven fabric, can also be associated with the underside of the
element 1 (see Figures 9 to 9C). This facilitates the subsequent
fixing of this element into the sole unit or onto the intersole
(or equivalent element) when this element is finally positioned,
as a foot support, within the relative footwear (for example the
boot 2).
Other variants of the invention can be devised in the light of the
aforegoing description) and are to be considered as falling within
the scope of this document.
