FOOTWEAR SOLE AND METHOD OF MANUFACTURE AND RELATED ASPECTS

A footwear sole comprises an first sole portion including at least one protruding male engagement part and a second sole portion including at least one recessed female engagement part having a shape which closely conforms to that of a corresponding male portion, whereby when a force is applied to the first sole portion in the direction of the second sole portion, the corresponding male engagement part is fixedly retained by the female engagement part. In this manner a shoe-sock may be fixed to the second or another portion of the sole without the need for any adhesive to be used.

FIELD OF THE INVENTION

The disclosed technology relates to a sole for an item of footwear and a method of manufacture of the same and related aspects, particularly but not exclusively, to a sole which enables footwear to be manufactured without requiring adhesive materials to be used to fix at least an upper fabric portion of the footwear item to a sole portion during manufacture of the footwear item.

BACKGROUND

Footwear, especially trainers and the like, are often manufactured using materials which are non-environmentally friendly. Whilst so-called “vegan shoes” and the like are well-known, they are usually constructed using techniques which make large-scale production challenging and/or have design comprises due to the manufacturing challenges

The embodiments described below are provided by way of example only.

SUMMARY

Some examples of the embodiments of the disclosed technology seek to provide a footwear sole which allows for adhesive free fixation of a shoe-upper or shoe-sock to sole components such as a mid-sole of an item of footwear.

A footwear sole comprises at least a first, or inner, sole portion which includes at least one protruding engagement part (also referred to herein as a male engaging part, element or portion). In one embodiment, at least three engagement parts are provided, for example, with one engagement part located in a heel region of the sole, a second engagement part located in a mid-foot region of the sole, and a third engagement part located in the fore-foot region of the sole. In one embodiment, the engagement parts extend from the underside of the inner sole to engage with a second sole portion of the footwear, in other embodiments a mixture of male and female engagement elements may be formed on each of the first and/or second sole portions. The second sole portion may comprise, for example, a mid-sole (or in some embodiments, an outer sole) includes at least one recessed engagement part (also referred to herein as a female engagement part and/or a reciprocating engagement part) which has a shape which closely conforms to that of the corresponding protruding engagement part. When a force is applied to drive the first sole portion against the second sole portion, each protruding engagement part is forced into engagement with a corresponding and reciprocating recessed engagement part. By locating the first sole portion within a shoe upper or shoe sock, such that the so-called male engagement parts protrude through the shoe-sock material, for example, through one or more apertures in the base or foot of the shoe-sock, the shoe-sock is fixed in place, enabling it to be secured to other parts of the footwear such as another sole portion, which may be the first sole portion or the second sole portion or another, for example, outer portion of the sole without the need for any adhesive to be used. This enables what is usually referred to “glue-less” footwear or shoes to be made which are both aesthetically appealing and which are capable of being mass produced in a factory environment. The terms “male” engagement part and “female” engagement part refer herein to the manner in which such fixation elements engage or couple with each other, for example, a “bolt” may be considered to form a male engagement part which engages with a reciprocating female engagement part in the form of a “nut”.

Some examples of embodiments of the disclosed technology relate to a footwear sole comprising:a first sole portion including at least one protruding male engagement part;a second sole portion including at least one recessed female engagement part having a shape which closely conforms to that of a corresponding male portion, whereby when a force is applied to the first sole portion in the direction of the second sole portion, the corresponding male engagement part is fixedly retained by the female engagement part

In at least one example embodiment of a footwear sole the first sole portion may comprise an inner sole positioned within a shoe-sock and the at least one corresponding protruding male engagement part passes through an aperture in said shoe-sock to engage with said recessed female engagement part.

In at least one example embodiment of a footwear sole the footwear sole may be used in the construction of an item of footwear and retains the position of the shoe-sock relative to the second sole portion whilst the shoe-sock is fixed to the second sole portion using non-adhesive based retaining technique.

In at least one example embodiment of a footwear sole, the non-adhesive base retaining technique may comprise stitching the shoe-sock to the second sole portion.

In at least one example embodiment of a footwear sole, the second sole portion may comprise a mid-sole of an item of footwear.

In at least one example embodiment of the disclosed technology, the footwear sole further comprises:at least one additional engagement part located in at least one of said at least one protruding male engagement part; and
at least one reciprocating additional engagement part located in at least one of said at least one recessed female engagement part.

In at least one example embodiment of a footwear sole, at least one of the at least one additional engagement parts may protrude from the base of the male engagement part and at least one of the at least one reciprocating additional engagement parts comprises an additional recess in the base of the female recessed engagement part.

In at least one example embodiment of a footwear sole, at least one of the additional engagement parts protrudes from the base of a recessed female engagement part and at least one of the at least one second additional engagement parts comprises a recess in the base of the male recessed engagement part.

In at least one example embodiment of the footwear sole the protruding additional engagement part forms a protrusion which comprises an additional component part that passes through at least part of the protruding male engagement part.

In at least one example embodiment of a footwear sole, the at least one protruding additional element comprises one or more of the following:a dowel and the reciprocal element comprises a recess;a screw and the reciprocal element comprises a recess;a bolt and the reciprocal element comprises a nut in a recess;a male part of a snap-fastener type mechanism and the reciprocal element comprises a female part of a snap-fastener mechanism.

Some examples of embodiments of the disclosed technology relate to a method of constructing an item of footwear, the method comprising: forming a first sole portion having at least one protruding male engagement part; forming a second sole portion having at least one recessed female engagement part; positioning the first sole portion within a shoe-sock, such that said at least one protruding male engagement part extends through the foot-base of the shoe-sock; positioning a second sole portion to align the at least one recessed female engagement part with a corresponding protruding male engagement part; and forcing the first sole portion against the second sole portion such that the male engagement and female engagement parts are affixed to each other and retain the shoe sock in position.

In at least one example embodiment of the method, the shoe-sock is further secured to at least one of the second sole using an adhesive free technique.

In at least one example embodiment of the method, wherein the adhesive free technique comprises stitching.

In at least one example embodiment of the method, the second sole portion comprises a mid-sole of an item of footwear, and the method further comprises covering at least part of the mid-sole with an outer sole.

In at least one example embodiment of the method, the method further comprises: forming at least one additional engagement part in at least one of said at least one protruding male engagement part; forming at least one corresponding reciprocating additional engagement part in at least one of said at least one recessed female engagement part, wherein the positioning of the second sole portion to align the at least one recessed female engagement part with a corresponding protruding male engagement part aligns the additional engagement part with the reciprocating female engagement part.

In at least one example embodiment of the method, forcing the first sole portion against the second sole portion such that the male engagement and female engagement parts are affixed to each other and retain the shoe sock in position further causes the additional engagement part and the reciprocating additional engagement part to similarly engage with each other.

In at least one example embodiment of the method, forcing the first sole portion against the second sole portion such that the male engagement and female engagement parts are affixed to each other and retain the shoe sock in position using a first mechanism for engagement further causes the additional engagement part and the reciprocating additional engagement part to be suitably located for engaging using a different mechanism of engagement.

In at least one example embodiment of the method, at least one of the at least one additional engagement parts protrudes from the base of the male engagement part and at least one of the at least one reciprocating additional engagement parts comprises an additional recess in the base of the female recessed engagement part.

In at least one example embodiment of the method, at least one of the additional engagement parts protrudes from the base of a recessed female engagement part and at least one of the at least one second additional engagement parts comprises a recess in the base of the male recessed engagement part.

In at least one example embodiment of the method, the at least one protruding additional element comprises one or more of the following: a dowel and the reciprocal element comprises a recess; a screw and the reciprocal element comprises a recess or cam-type locking mechanism in a recess; a bolt and the reciprocal element comprises a nut in a recess; a male part of a snap-fastener type mechanism and the reciprocal element comprises a female part of a snap-fastener mechanism.

Many other examples of main and secondary engagement mechanisms may be adopted in various embodiments of the invention, as would be apparent to one of ordinary skill in the art, where the secondary engagement mechanism is disposed within the main engagement mechanism, such as in a snap-fastening type of mechanism.

In at least one example embodiment of the method, the force applied to the first sole portion or second sole portion to cause the engagement of the first and a second sole portions is directed in a substantially perpendicular direction inwards towards the surface of one or other or both of the first (inner) sole and second (mid-sole) sole portions.

The inner sole may be formed integrally with at least one engagement member and/or the mid-sole may also formed integrally with at least one engagement member, for example, either by machine-tooling a blank or by casting a mold for one or both of the inner sole and/or mid-sole.

Whilst some examples of embodiments of the disclosed technology refer to the inner sole having as a primary engagement mechanism a protruding or male engagement portion, and the mid-sole (which in some embodiments may comprise an outer sole), comprises the reciprocal recessed or female engagement portion, in other examples of embodiments of the disclosed technology at least one engagement portion is configured as a female engagement portion in the inner-sole and the protruding male engagement portion is formed in the a sole portion.

DETAILED DESCRIPTION

Embodiments of the disclosed technology are described below by way of example only. These examples may represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

FIG. 1shows a schematic diagram of a side view of the exterior of an item of footwear10according to some examples of embodiments of the disclosed technology. The term item of footwear as used herein may refer to a shoe, boot, trainer or the like, which comprises an upper portion12covering an retaining a foot in contact with a lower portion14which supports the sole of a foot when it is within the item footwear. Upper portion12accordingly provides a “body” for the item of footwear comprising a shoe “sock”16which extends over the heal region20a, mid-foot region20b, and forefoot (or toe) region20c.

The item of footwear10is worn by inserting a foot is inserted via opening18located around the heal end20aof the shoe sock16. At least a portion of the shoe sock16may be constructed using elastomeric materials or the like in some embodiments so that the shoe sock16can be deformed to allow a foot to be inserted via opening18and then retract to retain the foot securely within the cavity portion of the shoe sock16. Alternatively one or more of a number of releasable fastening mechanisms are well known which may be used to secure a foot within the shoe sock16(for example, by using a shoe-lace, strap and buckle, or Velcro type strap, zipper, press-stud or even a hook and eyelet).

Also visible from the exterior of the item of footwear10is outer sole portion22which in this example of an embodiment of a footwear item10includes a lateral or sidewall portion24which extends laterally around the side of the lower portion14of the item of footwear10and a base portion26. Optionally, and as shown inFIG. 1, the outer sole portion22may further include a fixation portion28, which may allow the upper portion12of the item of footwear10to be fixed to the outer sole portion22, for example, by using a stitching technique.

Also visible from the exterior of the item of footwear10shown inFIG. 1is a mid-sole portion30which also comprises a base portion32and an upper portion34. Upper portion34forms a side-wall which extends around the shoe sock16and may further include a fixation section26which enables the shoe sock16to be fixed to the upper portion34of the mid-sole30, for example, by stitching.

The upper part ofFIG. 2Ais a side view of a schematic of the exterior of the lower portion14of an embodiment of an item of footwear10according to some embodiments of the disclosed technology such as the example of an embodiment of an item of footwear10shown inFIG. 1of the accompanying drawings. The lower part ofFIG. 2Ashows the alignment of the upper part showing lower portion14with the base26of the outer sole portion22.

InFIG. 2Badditional construction elements located within the item of footwear in the interior of the lower portion14are now visible comprising a first female engaging portion hereafter referred to as a “recess”,40alocated in the heel portion30aof the midsole30, a second recess40blocated in the mid-foot portion20bof the mid-sole30, and a third recess40clocated in the fore-foot portion20cof the mid-sole30. In some other embodiments of an item of footwear a different number of recesses may be provided in the mid-sole30.

As shown in the schematic diagram ofFIG. 2B, each recess38a,b,c, comprises sidewall portion(s)40a,band a base portion42. As shown, each recess38a,b,c, has a different depth dependent on the proportionate thickness of the mid-sole at the point where it is provided. The side-profile of the recesses38a,b,c, in the example of the embodiment shown inFIG. 2Bshows that for each recess the sidewalls40a,bmay make different angles with the base portions42. Also, as shown for recess38ainFIG. 1, the rear-foot or heel side wall40amay make an obtuse angle81being slightly or substantially greater 90 degrees with the base42of the recess38awhereas the side-wall40balong the fore-foot side of the recess38may make an acute angle φ1with the base of the recess42. In some embodiments θ1may be less than θ2which may be less than θ3, and similarly φ1may greater than φ2, may be greater than φ3, to accommodate the changing profile of the mid-sole (i.e. as the height of the mid-sole30generally decreases as one moves from the rear20ato the front or toe portion20cof the mid-sole30).

Further examples of the shapes of the recesses38a,38b,38care shown herein below with reference to the other drawings, and it will be appreciated that the shape of the recesses shown inFIG. 2Bare exemplary only, and a range of shapes from square, rectangular to parallelograms and rhomboids may be provided. There is a certain functional advantage to be obtained from some shapes, however, in terms of enabling better engagement or fixation with one or more male engagement parts44of an inner sole46(not shown inFIG. 2B), hereinafter referred to as engagement parts44.

FIG. 3Ais a black-and-white photograph providing a view of the medial side of an item of footwear10according to an example of an embodiment of the disclosed technology which indicates some further internal features of the item of footwear10. As shown in the example inFIG. 3A, the item of footwear comprises an upper portion12comprising a shoe sock16in which the opening18is closed using shoe-laces. Also visible inFIG. 3Ais the cut-way portion of the mid-sole30, and also inner-sole engagement parts44a,44bof an inner sole44. Inner sole44is retaining within the interior of the shoe sock16and is not visible inFIG. 3A, but in the heal region inner sole a protruding male engagement part44aand the mid-foot protruding male engagement part44bcan be seen.

FIG. 3Bis a black-and-white photograph providing a cut-away side view of the medial side of the lower portion12of the item of footwear shown inFIG. 3A. InFIG. 3B, internal features of the item of footwear10.FIG. 3shows inner sole46having three engagement parts44a,b,c, protruding through shoe sock16. In the heel portion30a, the base of the inner sole46is visible through an aperture in the heal-portion20aof the shoe sock16. Each protruding element44a,b,c, of the inner sole46conforms closely to the contour of a corresponding recess portion38a,b,cof the mid sole30. As shown inFIG. 3B, the rear inner sole engagement part44a, has a base element40which rests upon the base42of the corresponding recess38a. The inner sole engagement part side wall(s)48form a rear angle52aand a fore angle54awith base element50and as can be seen inFIG. 3B, which conform to the fore angle φ1and rear angle θ1of the recess in the mid-sole.

As the cross-sectional view shows, the shape(s) of the inner sole engagement parts, for example, the contours and the angles of at least one of the side-walls48of each of the inner sole engagement parts44a,b,cmake with the base of the engagement parts50a,b,c, are such that the engagement parts conform closely with the shape(s) of the corresponding sidewalls40and bases42a,b,cof the recesses38a,b,c, in the mid-sole30. To engage the inner sole46with the mid-sole30, force is applied in a suitable direction to cause the protruding engagement part44a,b,cto be inserted into the corresponding recesses38a,b,c.

Engagement may result, for example, from the shapes and/or relative sizes of the recess and/or engagement parts. For example, if the recess is suitable shaped so that a flange, lip or rim or the like is provided along at least one portion its top edge, this may deform sufficiently to allow the engagement part to be inserted but then function to retain the engagement part. Alternatively, if in profile, each of the recess and the engagement part have a suitable shape, e.g. polygonal e.g. a three-dimensional rhomboid type shape so that the base elements42and50are wider than the top of the recesses38a,38b,38c, then the mid-sole and/or the inner-sole engagement parts may be sufficiently deformed to allow insertion of the inner-sole engagement parts44a,b,c, into the corresponding recesses38a,38b,38cof mid-sole30such that they are not able to be disengaged afterwards during normal use of the footwear.

FIG. 3Bshows a further retaining feature56in the base of the mid-sole30, which may be provided to allow an additional retaining element to be provided within recess38a. Not shown in the example inFIG. 3Bis a corresponding additional engagement part58extending from engagement part44a, however, as would be apparent to one of ordinary skill in the art, such an engagement part could comprise an additional type of glue-less or adhesive free fixation mechanism could be used such as are well known in the art, for example, a screw, dowel, pin, nail, staple or the like, either directly into the mid-sole or with a “wall-plug” type fixing means being used as well. Well-known mechanisms such as a nut and bolt may also be used, for example, with a nut being held fixedly within a recess38of the mid-sole30for example, so as to engage with a corresponding bolt inserted into and protruding from a base50of an engagement part44of the mid-sole30, or, for example, a cam-lock could be used. The cam in the case of the latter example of additional fixation means could be inserted within a recess in one or more or all of the inner sole engaging portions, and these could then engage with a screw head inserted laterally in the mid-sole to engage in a manner well known to those of ordinary skill in the other. Other possible fixing mechanism may include, for example, a snap-fastener mechanism providing a sort of press-stud type of engagement mechanism.

As each of the inner sole engagement parts44a,b,c, protrudes through shoe sock16, the engagement of the inner sole46with the mid-sole30also fixes the shoe-sock16in position between the inner-sole46and mid-sole30. This enables glue-less or adhesion-free construction of at least part of the item of footwear10as the engagement of the inner sole46and mid-sole30holds the shoe sock in place and enables the mid-sole to be additionally fixed to the shoe-sock, for example, by stitching, stapling or by using other suitable technique.

FIG. 3Cis a black-and-white photograph providing a view of the base of the outer sole of an item of footwear10according to an example of an embodiment of the disclosed technology which has the mid-sole30partially cut away to remove the medial half. The medial side of the item of footwear now shows the bases of the protruding engagement parts44a,b,cof the inner sole.

FIG. 3Dis a black-and-white photograph providing a rear side-view of the heel region20aof the item of footwear10according to an example of an embodiment of the disclosed technology which shows the side-wall48of the rear engagement part44aof the inner sole (not visible as within shoe sock16).

FIGS. 4A to 4Care a black-and-white photographs enlarging the forefoot, mid-foot, and heel regions of the image shown inFIG. 3B.

InFIG. 4Athe forefoot of an item of footwear according to an embodiment of the disclosed technology is shown. InFIG. 4A, inner sole engagement part44cprotrudes through an aperture in shoe sock16to engage with recess38cin mid-sole30. The forefoot end side wall48of the engagement part44cforms an angle54cwith the base50cof the engagement part and the rear foot end foot sidewall48of the engagement part44cforms an angle52with the base50cof the engagement part44c. In the embodiment shown inFIG. 4A, the recess38cis retained within the midsole30and does not protrude to the base of the midsole or otherwise to any exterior part of the item of footwear10. The size and/or shape of the recess38cforms a retaining element which engages with the protruding engagement part44cof the inner sole46so as to grip the shoe sock16and hold this in place. Also shown inFIG. 4Ais a forefoot end side wall48of the inner sole engagement portion44bwhich makes an angle54bwith the base of the engagement part44b.

InFIG. 4Bthe mid-foot20bof an item of footwear10according to an embodiment of the disclosed technology is shown. InFIG. 4B, inner sole engagement part44bprotrudes through an aperture in shoe sock16to engage with recess38bin mid-sole30. The forefoot end side wall48of the engagement part44bforms an angle54bwith the base50bof the engagement part and the rear foot end foot sidewall48of the engagement part44bforms an angle52bwith the base50bof the engagement part44b. In the embodiment shown inFIG. 4B, the recess38bis retained within the midsole30and does not protrude to the base32of the midsole or any other exterior part of the item of footwear10. The size and/or shape of the recess38bforms a retaining element which engages with the protruding corresponding engagement part44bof the inner sole46so as to grip the shoe sock16and hold this in place. Also shown inFIG. 4Bis the forefoot end side wall48of the inner sole16retaining portion44cwhich makes an angle52cwith the base of the engagement part44c.

InFIG. 4Cthe rear foot or heal region20bof an item of footwear10according to an embodiment of the disclosed technology is shown. InFIG. 4C, inner sole engagement part44aprotrudes through an aperture in shoe sock16to engage with recess38ain mid-sole30. The forefoot end side wall48aof the engagement part44aforms an angle54awith the base50aof the engagement part and the rear foot end foot sidewall48aof the engagement part44aforms an angle52awith the base50aof the engagement part44a. In the embodiment shown inFIG. 4C, the recess38ais retained within the midsole30and does not protrude to the base32of the midsole or any other exterior part of the item of footwear10. The size and/or shape of the recess38aforms a retaining element which engages with the protruding corresponding engagement part44aof the inner sole46so as to grip the shoe sock16and hold this in place. Also shown inFIG. 4Cis the forefoot end side wall48bof the inner sole16retaining portion44bwhich makes an angle52bwith the base of the engagement part44b.

The inner sole engagement part44aand reciprocating recess38bas shown inFIG. 4Cmay engage solely by virtue of their three-dimensional shape, but they may also be provided with additional means of engagement, such as are described in more detail herein below, one example of such an additional means of engagement is the slot- or groove like recess56shown in the base of the recess38in midsole30, such as could engage with an additional corresponding element extending from the inner sole engagement part44a(not shown inFIG. 3C). Such an additional engagement part60could be provided by a dowel or the like protruding or being formed as an extrusion from the base50aof the engagement part44a. Alternatively, a recess could be provided in engagement part44ainto which a dowel or other suitable fixing means such as a screw or pin etc., could be provided.

FIGS. 5A to 5Dare black and white photographs showing a different views of a model of a base of an item of footwear according to an example of an embodiment of the disclosed technology.

InFIG. 5Aan example of a midsole30according to an example of an embodiment of the disclosed technology is shown as a unitary body in which the three recesses38a,b,chave being integrally formed (for example, by molding the entire midsole30from a suitable material/materials and/or machine tooling a blank or any other well-known manufacturing method include 3D printing). Similarly, the inner sole46is shown as a single or unitary body formed with three protruding male engagement parts44a,44b,44c, which may be machine tooled with the inner sole from a blank and/or molded and/or otherwise extruded from the underside of the foot-bed of the inner sole using a suitable manufacturing method, such as, for example, 3D printing. In other embodiments however, the midsole30may be formed from a blank and the design elements such as the side wall34and fixation region36may be formed after the main body of the mid-sole has been formed.

FIG. 5Bis an enlargement of the image ofFIG. 5Ashowing in more detail the form of the inner sole46from which extend the three sole engagement parts44a,44b,44c.

FIG. 5Cshows in more detail another view an example of a midsole30according to an example of an embodiment of the which comprises a side-wall34and fixation rim36the three engagement parts or recesses38a,38b,38c. Each recess38a,b,c, has the shape of a rhombus in side profile and a rectangle when viewed from above. The shape of each recess38a,b,cmay not be the same and they may differ in some embodiments and even with the same shape their dimensions will change in order to be accommodated completely within mid-sole30. Each recess accordingly has four walls40surrounding a base42.

InFIG. 5C, the base42aof recess38ain the heel or rear end20aof the midsole30is deeper than those of the mid- and fore-foot recesses38band38cand includes an additional retaining element comprising a further recess56, which can be seen more clearly in the image shown inFIG. 5Dwhich is an enlargement of the image shown inFIG. 5C.

In the embodiment of the rear-end recess38aof the mid-sole30shown inFIG. 5C. the base42ahas an additional cut out section56which allows further engagement with inner sole46.

FIGS. 6A to 6Dare schematic cross-sectional views of different examples of engagement mechanisms for the inner and outer sole portions according to some embodiments of the disclosed technology.FIGS. 6A to 6Balso show as large arrows an example of a direction in which a force applied to the inner surface of the inner sole46causes engagement with the mid-sole30(those of ordinary skill in the art will appreciate that a force in the opposite direction applied to the outer surface of the mid-sole30may have the equivalent effect, as would applying forces in both directions).

In the embodiment of the inner and mid-foot engagement mechanism shown inFIG. 6A, inner sole46has an integral engagement part44which protrudes through shoe-sock16to engage with mid-sole30. In construction and use, the flexing of the item of footwear10means that it can be sufficient to provide a “wedge-like” engagement mechanism which has an acute (less than 90 degrees) fore-foot end angle θ and an obtuse (greater than 90 degrees) rear-foot end angle φ with the top of the mid-sole30which result in the side-walls48of the retaining wedge enabling the inner sole wedge to be slotted or slipped into place by pushing the inner sole46in a direction along from the rear-foot end of the mid-sole to the fore-foot end until it clicks into place. Whilst this may be sufficient to retain the shoe sock16in place during construction of the item of footwear when this is attached, for example, by stitching or stapling, to the mid-sole30, this may not be an optimal design for all gaits when the item of footwear is being worn and in use.

FIG. 6Bshows another example of an engagement part44protruding from inner sole46through shoe sock16to engage with a corresponding recess38with which the engagement part closely conforms in shape. In this example, the fore-foot end angle θ and a rear-foot end angle φ are both acute angles (i.e. both are less than 90 degrees, for example, they may be 85, 80 or 75 or else, for example, 60, 45, or 30 degrees etc.). However, ideally the angles are selected so that they are close enough to 90 degrees to allow the protruding inner sole engagement part to be forcibly inserted into the corresponding recess38of the midsole30yet not so close to 90 degrees that there is not sufficient engagement to hold the inner sole and mid-sole together when the footwear is being constructed and/or in use.

FIG. 6Cshows yet another example of an engagement part44protruding from inner sole46through shoe sock16to engage with a corresponding recess38with which the engagement part closely conforms in shape. In this example, the fore-foot end angle θ is acute and the rear-foot end angle φ is obtuse but the same additional engagement part56could be provided when are both acute angles as shown inFIG. 6B. The additional engagement part shown inFIG. 6Ccomprises a nodule or dowel like extension in the base of engagement part44which is housed within cavity56in the mid sole30, however, it will be apparent to anyone of ordinary skill in the art that a number of other engagement mechanisms may be formed integrally with the inner sole46or provided within the inner sole46, for example, in the form of a dowel, pin, screen or asFIG. 6Dshows, a nut and bolt like mechanism. InFIG. 6, the base of the mid-sole30includes a recess56providing an additional engagement mechanism which is configured to accommodate a nut62in the base42of the recess38. InFIG. 6D, a bolt60is shown extending through the inner sole engagement part44to additionally engage with the bolt62within recessed base42of the recess38in midsole30.

Other embodiments of the invention may use other forms of engagement mechanisms and combinations of integrally formed (e.g. molded) engagement mechanisms with additional engagement mechanisms.

For example, in some embodiments the inner sole46may be formed integrally with a protruding hollow element having an inner aperture which forms an additional secondary engagement mechanism may be provided, such as a bolt or screw or a snap-fastener type of engagement portion (for example a male snap-fastener portion). In this example embodiment, the mid-sole30comprises a reciprocating engagement portion, for example, a female snap-fastener. Further additional fixing means may also be provided in the form of a secondary fastening mechanism, for example, the male engagement part44may be provided with one or more apertures in the base42and shaped to allow a further secondary engagement portion60in the form of a screw, bolt, or secondary male or female snap-fastener type element to pass through and engage with a corresponding secondary reciprocating snap-fastening engagement element formed in the female engagement part recess of the mid-sole30so as to provide an additional form of fixation mechanism to fixedly engage the inner sole46with the midsole30.

In such a manner an inner sole may, for example, be provided with at least one integrally formed male engagement portions44a,b,c, each engagement part or portion configured to function as one or more nested male snap-fastener mechanisms and the mid-sole may be integrally formed with one or more female recess portions38a,b,c, each providing one or more reciprocating nested female snap-fastener mechanisms arranged to receive and engage with the male snap-fastener mechanisms in one embodiment of the disclosed technology.

Those of ordinary skill in the art will appreciate that in some embodiments it may be possible instead and/or in addition to forming apertures in the shoe-sock through which the protruding male engagement part(s)44extend to instead deform the shoe-sock sufficiently to allow the contours of the inner sole46engagement parts44to engage with the reciprocating engagement parts in the mid-sole30.

Some embodiments of the invention may invert the male and female engagement elements so that the female is housed within inner sole46and the male within mid-sole30.

The side profile of the secondary male or female engagement portions may be tapered when in position within the inner sole so as to conform to the inner surface of the inner sole46, so that in a side view along the axis of the footwear sole, from either the medial side of the foot or the distal lateral side of the foot the top profile of a secondary engagement portion may take the form of a wedge.

Whilst the examples of recesses and engagement parts shown in the accompanying drawings are “wedge-like” a number of different shapes and configures may be used providing they are configured to allow the inner sole46to engage with the mid-sole30, as a “snap-type” fastener type of design, for example, when viewed from above looking down on the shoe or in a direction where the base of the shoe faces the viewer, the mid-sole retaining elements comprising the retaining recesses and the correspondingly shaped inner sole engagement parts may instead of being rectangular instead comprise a square, a circle, an oval, a hexagon or other polygon, or a star type shape etc. etc. In some embodiments, the inner sole may be constructed so as to contain the recesses or “female” engagement part, with the male “protruding” engagement part being provided in the mid-sole.

Whilst the term “mid-sole” has been used here, in some embodiments of the invention, this may form the outer-sole of the item of footwear10.

Any reference to ‘an’ item refers to one or more of those items. The term ‘comprising’ is used herein to mean including the method blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and an apparatus may contain additional blocks or elements and a method may contain additional operations or elements. Furthermore, the blocks, elements and operations are themselves not impliedly closed.

The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. The arrows between boxes in the figures show one example sequence of method steps but are not intended to exclude other sequences or the performance of multiple steps in parallel. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought. Where elements of the figures are shown connected by arrows, it will be appreciated that these arrows show just one example flow of communications (including data and control messages) between elements. The flow between elements may be in either direction or in both directions.