EP3998894A1

EP3998894A1 - Method for manufacturing a footwear article

Info

Publication number: EP3998894A1
Application number: EP20743642.9A
Authority: EP
Inventors: Carly TATIBOUET; Anne-Claire MAGNARD; Jarvis HUANG; Terry Lee
Original assignee: Decathlon SE
Current assignee: Decathlon SE
Priority date: 2019-07-17
Filing date: 2020-07-16
Publication date: 2022-05-25
Also published as: WO2021009326A1; CN114269195A; FR3098689B1; FR3098689A1

Abstract

The present invention relates to a method for manufacturing a footwear article, comprising the manufacture and provision of a first knitted tubular portion (20) having at least one hot-melt portion and of one or more functional components (60;70;75); the formation of a footwear set (40) comprising the first knitted tubular portion (20) and one or more functional components (60;70;75); and the transformation of the footwear set (40), which is placed on a preform in the form of a foot (50), into a rod (400). The transformation step comprises a thermoforming step and at least one partial securing step of the at least one functional component (60;70;75) to the first knitted tubular portion (20), said thermoforming and securing steps taking place in a single step comprising a vacuuming of the footwear set (40).

Description

Manufacturing process of an article of footwear

Technical area

The present invention relates to a method of manufacturing an article of footwear, in particular for practicing a sport.

The present invention relates to a method of manufacturing an article of footwear using one or more three-dimensional tubular knitted component (s) for the production of an upper comprising an integrated sole part.

Prior art

The articles of footwear of the state of the art generally include two main elements, namely an upper and a sole structure. The upper is secured to the sole structure and forms a void or space for accommodating the foot within the article of footwear to securely and comfortably receive the foot. The sole structure is secured to the lower area of the upper, and is thus positioned between the upper and the ground.

In articles of footwear, for example, for practicing a sport, the sole structure may include a midsole and an outsole, the outer face of which is intended to come into direct contact with the ground.

The midsole typically includes a polymeric foam material that dampens impact reactions with the ground to decrease impact feedback forces generated on the foot and leg during walking, running, or other activities while walking. wearing of the footwear.

Additionally, the midsole may comprise one or more chamber (s) filled with a fluid, one or more damping part (s) or other elements which make it possible to attenuate the return forces. impact and improve stability or even influence foot movements and therefore proprioception.

The outsole is secured to the undersurface of the midsole and provides a ground engaging portion of the sole structure, which ground engaging portion is formed of a wear resistant and durable material, such as for example a material based on rubber or on a synthetic elastomer. The sole structure may also include an inner liner positioned within the accommodating volume of the foot of the upper and near the undersurface of the foot to enhance the comfort of the footwear.

The upper usually has many parts, such as lateral quarter, mid quarter, front toe cap, tongue, heel, buttress rear, an upper, a tightening device with in particular loops / (eyelets for passing a lace) and a lace, an internal lining and possibly other parts. Some of these parts can be in several parts. The manufacture of a shoe thus requires assembling these different parts in order to form a three-dimensional rod by cutting these parts and assembling them flat.

The shank generally extends above the instep and into the toe areas of the foot, along the lateral and medial sides of the foot, and around the ankle area of the foot. According to certain applications such as for example for basketball, or even hiking, the rod can extend upwards and around the ankle to provide additional support and protection to the ankle. The clamping device is often incorporated into the rod to adjust the size of the rod and thus allow the foot to enter and withdraw from the void formed inside the rod. The upper may also include a tongue which extends under the tightening device, eg, the lacing system, to adjust the footwear, and the upper may include a rear reinforcement element to limit heel movement. The assembly of these different components / elements / parts requires a lot of time and can lead to errors in the manufacture of the article of footwear. The potential number of errors can thus be significant and make the manufacturing process more complex and therefore also make it more expensive.

The shaped upper, and therefore in terms of volume, in particular by assembly at the heel, for example using a seam, is associated in a known manner with a sole element, in particular entering into a sole structure, for define a footwear volume.

The upper can thus be glued to the sole element by a layer of glue; it can be glued to an insole which is relatively rigid.

Alternatively, the upper can be assembled to the sole element by shaping the upper using different seams and then by assembling the upper to the insole by sewing using the so-called stroebel technique. The insole is in this case generally flexible so that it can be sewn. The insole thus forms the sole part or bottom of the upper.

The time and costs associated with transporting, storing, cutting and assembling the various components are very important. In addition, during the cutting and assembly of components, a lot of waste is generated. Footwear with a large number of components in different materials are more difficult to recycle because it is particularly complex to separate the components for recycling. Thus, by decreasing the number of different components entering into the composition of a shoe it is possible to reduce the amount of waste and improve the efficiency of the manufacturing process of such footwear and the recyclable nature of the uppers.

It has thus been proposed to produce articles of footwear using an upper obtained from the manufacture of a three-dimensional knitted tube. These methods firstly implement the knitting of the primary upper by knitting a tubular knitted component in the shape of a substantially sock.

The method then comprises making a longitudinal cutout in the sole portion of the knitted tubular component, then laying out this knitted tubular component flat using the longitudinal cutout so as to reveal an outer face on which a or functional component (s) can be laid out flat. These functional components such as a logo, reinforcing elements, lacing eyelets, a hard toe or an upper or even a heel reinforcement, are applied manually to the flat outer face of the knitted tubular component and then secured, for example by gluing and / or sewing. The joining by gluing can be carried out for example manually using an iron. The longitudinal cut made in the sole portion is then closed, for example using a seam. A footwear assembly is then obtained comprising the primary upper secured to one or more functional component (s). This shoe assembly is placed on a preform in the shape of a foot, then is thermoformed in the shape of the foot of the preform to form the final upper. The dimensions of the preform corresponding to a given foot size, many preforms are necessary. The preforms are made of plastic or of composite material (s). Finally, a sole element such as a midsole is secured to the sole portion of the upper.

The production of a longitudinal cut in the sole portion of the knitted tubular component in order to place the latter flat and be able to carry out its functionalization requires additional steps. Moreover, the fact of joining functional components on a knitted tube arranged in a plane, only makes it possible to functionalize small areas of the knitted tubular component. It is not possible to lay the entire knitted tube flat, despite the longitudinal opening. It is thus not possible to functionalize the entire surface of the rod in three dimensions. In addition, the functional components added during the flat functionalization can be thermally damaged during the following thermoforming step such that this further limits the size and / or the nature of the functional components which can be used. There is therefore a need for a method of manufacturing an article of footwear allowing access to the entire footwear assembly in three dimensions - intended to form the upper - during its functionalization, without limitation in size and number. accessible functionalization zones.

There is also a need for a method of manufacturing an article of footwear which limits the number of assembly steps but does not degrade the functional component (s) used.

There is also a need for a manufacturing process making it possible to reduce the manufacturing time and to improve the quality of the rod obtained.

Disclosure of the invention

The present invention relates to a method of manufacturing an article of footwear, limiting the number of components and / or parts, thus making it possible to significantly reduce the manufacturing time, the number of manufacturing steps, limiting assembly errors. , and minimizing the amount of waste.

The present invention also relates to a method offering more possibilities in the aesthetic design of the rod, and making it possible to improve the stabilization of the rod. A subject of the present invention is thus a method of manufacturing an article of footwear, overcoming the aforementioned problems, in that it comprises the steps of:

(i) - providing a first knitted tubular part comprising one or more hot-melt portion (s), and one or more functional component (s);

(ii) - forming a footwear assembly comprising the first knitted tubular part, and one or more functional component (s);

(iii) - transforming the footwear set, placed on a preform in the shape of a foot, into a rod, the transformation step comprises:

- thermoforming of the footwear assembly according to the foot shape of the preform, and

- the at least partial securing of the functional component (s) to the first knitted tubular part.

In addition, the thermoforming and the joining take place in a single step comprising a vacuum of the footwear assembly.

Advantageously, the securing of the functional component (s) to the first knitted tubular part is carried out at the same time as the thermoforming which makes it possible in particular to eliminate the step of cutting in the sole part, the step of flattening, the step of closing the blank, as well as the step of securing the functional component (s) before the thermoforming step. Advantageously, the footwear assembly is placed against the outer surface of the preform.

Preferably, the functional component (s) is / are arranged on the first knitted tubular part arranged in three dimensions in the shape of a foot, in particular placed on a preform in the shape of a foot. a foot, in particular the preform used during the transformation step (iii). This arrangement offers more possibilities for personalizing and stabilizing the first knitted tubular part, in particular because all of its exterior and interior surfaces are fully available.

During step (ii), the functional component (s) can / can be kept arranged on the first knitted tubular part and / or the second knitted tubular part by sewing and / or bonding and / or by welding, in particular thermal, in particular by ultrasound, for example using one or more holding point (s); in particular by one or more stitch (s) of seam and / or one or more point (s) of glue and / or one or more point (s) of welding, for example ultrasonic welding. This arrangement makes it possible to maintain the functionalization component (s) in its functionalization location (s). In addition, carrying out the thermoforming and securing step, in particular by application of heat and a vacuum, optionally combined with a flow of gas (s), in particular water vapor, so concomitantly during step (iii), makes it possible to avoid performing thermoforming on a footwear assembly which would have already undergone a heat treatment during the flat functionalization, and thus avoids damaging the functional components and the first tubular part knitted.

Advantageously, the evacuation makes it possible to press the footwear assembly onto the preform, which is sucked against the preform. Preferably, the vacuum is carried out in a molding volume receiving the footwear assembly.

The molding volume can be formed between the preform in the form of a foot, and a counter-mold (in particular rigid, for example in several parts) or a flexible membrane which conforms to the preform (covered with the footwear assembly).

The flexible membrane can be in a flexible and deformable material, for example silicone or polyurethane. The membrane is by definition airtight.

Vacuuming also improves the aesthetic appearance of the rod, and the mechanical properties of the rod. It also makes it possible to secure one or more functional component (s) in the form of a film in a perfectly regular manner with good attachment to the tubular textile parts, in particular to cover an outer surface. extent of the footwear assembly to provide an external covering, continuous or discontinuous.

The transformation step (iii) makes it possible, by supply of heat, to melt / soften the hot-melt portion (s), the footwear assembly is also compressed and pressed against the outer surface of the preform. Following the cooling of the footwear assembly, in particular to ambient temperature, maintained in pressure against the outer surface of the preform, the footwear assembly then permanently retains the shape of the foot of the preform. The melting or softening, then the cooling, of one or more hot-melt portions (s) make it possible to impart to the footwear assembly the foot shape of the preform, and possibly to secure the functional component (s) ( s) to the first tubular part.

By definition, thermoforming involves the application of heat to the footwear assembly, and this for a time and at a temperature sufficient to obtain thermoforming of the footwear assembly to the foot shape of the preform. Preferably, the temperature applied is greater than or equal to the melting and / or softening temperature (s) of the hot-melt portion (s) of the first knitted tubular part and / or of the second part. tubular knitted.

The functional component (s) can / can be joined together by means of the hot-melt portion (s) that the first and second tubular part (s) comprises / comprise (s) knitted (s), and / or the hot-melt portion (s) that comprises / comprise the functional component (s) itself, and / or a or adhesive means (s), in particular at least partly thermofusible. In the latter case, the adhesive means (s) is / are considered to be equivalent (s) to one or more functional component (s) according to the invention having an intermediate securing function .

The functional component (s) according to the invention has / have at least one function chosen from the following functions: cushioning, reinforcement, adhesion, continuous or discontinuous protective coating, aesthetic, or a combination of the latter.

The first knitted tubular part, and / or the second knitted tubular part (defined below) can / can be knitted on a double needle bed flat knitting machine, or on a circular knitting machine.

The step of transforming (iii) the article of footwear into an upper comprises simultaneously making the functional component (s) and possibly the first and second tubular parts knitted together, and the thermoforming. Preferably, the first knitted tubular part and / or the second knitted tubular part is / are each, an envelope comprising a sole part (intended to come under the wearer's foot), a lateral part (intended to come in contact with the lateral side of the wearer's foot), a medial part (intended to come into contact with the medial side of the wearer's foot), a front part in the extension of the medial, lateral and sole parts (intended to cover the front of the foot), and a rear part in the extension of the medial, lateral and sole parts (intended to cover the rear of the foot, and therefore the heel, and possibly the ankle). The envelope can be arranged so as to cover all or part of the ankle and possibly extend above the malleolus.

The front portion of the envelope may include a tongue and a distal pocket for receiving the toes. The tongue may be integral with the front part only along its front edge or integral with the front part, in addition to its front edge, along its lateral and medial edges respectively to the lateral and medial parts.

The rear portion may include a pocket configured to receive the heel.

The envelope preferably defines a volume or void intended to accommodate the wearer's foot. In one embodiment, the first knitted tubular portion is of unitary knitted construction with the knitted shell such that the shell and the first knitted tubular portion comprise a single knitted piece.

In one embodiment, the second knitted tubular portion is of unitary knitted construction with the knitted shell such that the shell and the second knitted tubular portion are in a single knitted piece. In this case, the knitted piece forming the second knitted tubular part and the knitted piece forming the first knitted tubular part are secured to each other, in particular during the transformation step (iii), for example by sewing.

In another embodiment, the first knitted tubular portion and the second knitted tubular portion are each in an envelope, the two envelopes being of unitary knitted construction with their respective first and second knitted tubular portions, and between them, so as to include a single knitted piece.

The first knitted tubular part and / or the second knitted tubular part comprises / comprise one or more threads, in particular mechanically assembled by knitting.

The yarn (s) may be selected, independently, from: monofilament yarn (s), fiber spun yarn (s), multifilament yarn (s), and a combination of these latter. The yarn (s) can / can be non-hot-melt, at least partially hot-melt or totally hot-melt, or a mixture of the latter.

Thus, the first knitted tubular part and / or the second knitted tubular part comprises / comprise (each) one or more yarn (s) at least partly hot-melt (s), and / or one or more non-hot-melt yarn (s) ( s).

The transformation step (iii) makes it possible, by supply of heat, to melt / soften the hot-melt portion (s), the footwear assembly is also compressed and pressed against the outer surface of the preform. Following the cooling of the footwear assembly, in particular to ambient temperature, maintained in pressure against the outer surface of the preform, the footwear assembly then permanently retains the shape of the foot of the preform. The melting or softening, then cooling, of one or more hot-melt portions (s) makes it possible to impart to the footwear assembly the shape of the foot of the preform, and concomitantly to secure the component (s) functional (s) to the first tubular part.

The duration of step (iii), in particular of thermoforming, may be greater than 0 seconds, and less than or equal to 30 minutes, in particular less than or equal to 5 minutes.

The footwear assembly can thus comprise one or more material (s) which are fusible by nature by application of heat but which will not be activated during step (iii). This (these) material (s) is / are considered in the present text to be non-hot melt (s). The thermo-fusible wires, in particular at least partially, can be wires comprising at least two components, in particular of the bi-corn laying type, a first component having a melting temperature less than or equal to the heating temperature (s) set. (s) implemented during step (iii), and a second component having a given melting or degradation temperature greater than the heating temperature (s) implemented during step ( iii).

The thermo-fusible wires can be single-component wires, the melting temperature of which is less than or equal to the heating temperature (s) implemented during step (iii). The first component can be chosen from polyurethanes, in particular thermoplastic polyurethanes; polyamides, such as polyamide 6 or 66; polyolefins, such as polypropylene (PP) or polyethylene (PE); preferably from polyurethanes.

The first component can be colored or colorless and / or opaque or transparent.

The second component can be chosen from polyolefins, such as high density polyethylene; polyamides, such as polyamide 4-6, polyamide 6 or 6-6; polyesters, such as polyethylene terephthalate.

The bicomponent yarns can be of the core-mantle type, the core being formed from the second component and the mantle being formed from the first component.

Preferably, the heating temperature (s) applied to the footwear assembly during the transformation step (iii) is / are greater (s) or equal (s) to 80 ° C, again of preferably greater than or equal (s) to 90 ° C, preferably greater than or equal (s) to 100 ° C.

Preferably, the heating temperature (s) applied to the footwear assembly during processing step (iii) is / are less than or equal to 250 ° C, again of preferably less than or equal (s) to 200 ° C, preferably less than or equal (s) to 180 ° C.

Preferably, the hot-melt component (s) have a melting or softening temperature lower (s) or equal (s) to the heating temperature (s).

The yarn (s), in particular non-thermofusible (s), may / may comprise one or more material (s) chosen, independently, from synthetic, artificial (for example lyocell or viscose), natural, mineral materials or inorganic, and a combination of the latter, preferably from synthetic, artificial and natural materials, in particular synthetic.

The synthetic material (s) preferably comprise: polyesters, in particular polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyamides (such as PA 6, PA 6-6, PA 12, PA 4-6); polyolefins (polypropylene, polyethylene, PEEK, PEUHMW); aramids, in particular meta-aramid or para-aramid or a mixture of the latter; vinyl acetates (eg EVA), polyacrylics (eg polyacrylonitrile); elastomers; elasthanes, or a mixture of the latter, preferably polyesters and polyolefins.

The natural material (s) preferably comprise: cotton, viscose, linen, sisal, wool, jute, silk, hemp. The mineral or inorganic material (s) preferably comprise: carbon, mineral fibers, such as rock fiber, glass.

The monofilament yarns preferably have a diameter greater than 0.01 mm and less than or equal to 5 mm, more preferably greater than or equal to 0.1 mm and less than or equal to 2 mm.

The multifilament yarns and / or yarns spun fibers preferably have a count greater than or equal to 10 dtex and less than or equal to 1000 dtex, more preferably greater than or equal to 30 dtex and less than or equal to 500 dtex.

Multifilament yarns can be FDY (Full Drawn Yarn), DTY (Draw Textured Yarn) or POY (Partially Oriented Yarn) textured yarns, or a mixture of these.

In the present text, the term “longitudinal” is understood to mean the direction extending over a length or a major axis of the article of footwear or upper. In some cases, the longitudinal direction may extend from a forefoot region to a rearfoot region of the article of footwear or the upper.

The first and second knitted tubular part (s) may / may also comprise one or more elastic yarn (s), in particular made of elastane.

In the present text, the term “lateral” is understood to mean the direction extending over a width or a minor axis of the article of footwear or of the upper or of the assembly of footwear. The lateral direction can thus extend between the medial side and the lateral side of the article of footwear.

In the present text, the term “vertical” is understood to mean the direction extending generally perpendicular to the lateral direction and to the longitudinal direction.

In the present text, thermoforming is understood to mean the action of shaping the footwear assembly by heating to the shape of the foot of the preform, that is to say by combining the melting of the hot-melt portion (s) (s ) with a means which presses the footwear assembly against the foot shape of the preform, then cooling the footwear assembly having the foot shape of the preform, in particular at room temperature.

In one embodiment, step (iii) comprises placing the footwear assembly previously placed on the foot-shaped preform in a molding volume. Said molding volume is preferably delimited by a mold comprising one or more parts, in particular two parts, and in particular the outer surface of the preform.

Said molding volume can also be delimited between an airtight and flexible membrane and the outer surface of the preform. The molding volume has a shape that is substantially complementary to that of the preform.

In a variant, during step (iii) of transformation, is applied, in a single step, to the footwear assembly, in combination with heat, a flow of gas (s), in particular vapor of water.

Advantageously, the flow of gas (s), in particular water vapor, makes it possible to distribute the heat better over the footwear assembly, to soften the latter in order to better match the preform, and to protect the threads from thermal degradation. . The water vapor also allows the transformed textile parts to retain a soft, non-rigid hand or feel.

The combination of these parameters makes it possible to obtain very good bonding and perfect shaping of the footwear assembly to the foot shape of the preform. The flow of gas (s), in particular water vapor, is in particular applied concomitantly to the footwear assembly during thermoforming and joining.

A non-exhaustive explanation of these technical effects, and non-limiting of the present invention, would be that the water vapor would act as a plasticizer on the textile and / or polymeric elements that the footwear assembly comprises, in particular the inserts and / or second knitted tubular part (s).

In a variant, the method comprises providing a second knitted tubular portion, optionally comprising at least one hot-melt portion, and the footwear assembly in step (ii) comprises the first and second knitted tubular portions, at least in part. , superimposed, in conjunction with one or more functional component (s).

The provision of a second knitted tubular part makes it possible to reinforce the upper, and to provide more functionalization and stabilization to the upper.

The first knitted tubular part may be the same or different from the second knitted tubular part.

Preferably, the second tubular part is placed in the reception volume of the first tubular part when the footwear assembly is on the preform. Of course, this can be reversed depending on the type of footwear desired, the first tubular part can be arranged in the receiving volume of the second knitted tubular part for the formation of the footwear assembly placed on the preform. In the latter case, the first knitted tubular part in particular at least partly forms the internal layer of the upper. Preferably, the second knitted tubular portion comprises an outer surface and an opposing inner surface, and the inner surface of the second tubular portion at least partially covers the outer surface of the preform.

Preferably, the first knitted tubular portion comprises an outer surface and an opposing inner surface, and the inner surface of the first tubular portion is disposed against, at least in part, the outer surface of the second tubular portion. The outer surface of the first knitted tubular part thus opens directly into the molding volume.

In a variant, the joining, in step (iii) allows the joining, at least partially:

- first and second tubular parts knitted together, and

- optionally one or more component (s) functional (s) to the second knitted tubular part.

In a variant, at least one of the functional component (s) is a polymeric film, at least in part thermofusible.

The polymeric film may be in one or more material (s) chosen from among the synthetic materials mentioned above, and polyurethane, or a combination of the latter.

In one embodiment, the polymeric film comprises / is made of polyurethane. In a variant, after step (iii), said film forms a coating (or has dimensions determined so as to form a coating) covering at least 10%, preferably at least 25%, more preferably at least 40% , preferably at least 50%, even more preferably at least 70%, in particular at least 80%, or 98% to within +/- 2%, of the outer surface of the upper (or of the first knitted tubular part), in particular except for the outer surface of the sole portion of the upper (or the first knitted tubular portion).

The coating can be continuous or discontinuous, and / or in the form of pattern (s) (identical (s) or different (s)) and / or point (s), but overall covering the aforementioned% of the outer surface).

Preferably, this arrangement is obtained by combining during step (iii), heat, a flow of gas (s), in particular water vapor, and a vacuum, applied to the footwear assembly. .

Advantageously, the method according to the invention makes it possible to functionalize one or more extended areas of the outer surface of the first knitted tubular part, and therefore ultimately one or more extended areas of the outer surface of the upper. In a variant, at least one of the functional component (s) is chosen from: a polymeric film at least partially thermofusible, a heel reinforcement element, a logo, an aesthetic element, a hard toe, a reinforcing element of a lacing zone, an auxiliary knitted tubular part, a textile element, a cushioning element such as foam, or a combination thereof.

In one embodiment, at least one of the functional component (s) is a damping element, in particular a foam.

In one embodiment, at least one of the functional component (s) is chosen from: an at least partially thermofusible polymeric film, a heel reinforcement element, a logo, an aesthetic element, a hard toe, a piece of reinforcement of a lacing zone, or a combination of these.

The textile element may comprise one or more woven, knitted, non-woven element (s) or a combination thereof.

The auxiliary knitted tubular portion may be the same or different from the first knitted tubular portion. The description relating to the first or second tubular part applies to the auxiliary tubular part.

Alternatively, said method comprises providing a knitted tubular component, and the first knitted tubular portion and the second knitted tubular portion are of unitary knitted construction with the knitted tubular component so as to form a one-piece knitted element.

In this case, the first and second knitted tubular parts are knitted at the same time on the knitting machine, and are therefore in the same knitted piece.

Alternatively, but not preferably, the first knitted tubular part is in a different knitted piece from the knitted piece forming the second knitted tubular part.

In a variant, said method comprises the arrangement of at least one functional component between the first knitted tubular part and the second knitted tubular part, in particular during step (ii) and / or during step (iii).

Alternatively, the first knitted tubular portion forms an inner layer of the upper and the second knitted tubular portion forms an outer layer of the upper.

In a variant, the first knitted tubular part comprises one or more yarn (s) at least in part thermofusible (s), the ratio of the mass of the yarn (s) at least in part thermofusible (s) to the total mass of the first knitted tubular part, is greater than or equal to 20%, preferably greater than or equal to 40%, more preferably greater than or equal to 60%, in particular greater than or equal to 80%. In a variant, the second knitted tubular part comprises one or more yarn (s) at least in part hot-melt (s), the ratio of the mass of the yarn (s) at least in part hot-melt (s) on the total mass of the second knitted tubular part, is less than or equal to 80%, preferably less than or equal to 60%, more preferably is less than or equal to 40%, in particular less than or equal to 20%.

In a variant, the first knitted tubular part comprises an opening zone for introducing the foot and the second knitted tubular part comprises an opening zone for introducing the foot, said zones for introducing the opening of the foot are superimposed. . In a variant, the at least partially thermofusible yarn (s) form (s) said at least one thermofusible portion, preferably having a melting temperature less than or equal to Tl, which is preferably less than or equal to the heating temperature (s).

In a variant, step (iii) comprises heating the preform to a heating temperature greater than or equal to Tp, with Tp> Tl.

In a variant, step (iii) comprises heating the molding volume to a heating temperature greater than or equal to Tvm, with Tvm> Tl.

The temperatures Tp and Tvm can be the same or different.

The method according to the invention makes it possible to apply differentiated heating temperatures, taking into account the nature of the materials of the footwear assembly.

In a variant, the upper obtained in step (iii) comprises a sole part, and said method comprises a step of securing at least one sole element chosen from an intermediate sole, and an outsole to said sole. sole portion of the upper. In a variant, the preform comprises an interior volume and perforations opening onto its exterior surface, said interior volume and the perforations are in fluid connection.

Preferably, a flow of gas (s), in particular water vapor, is sent to the footwear assembly through the perforations of the preform.

Advantageously, the arrangement of the perforations of the preform makes it possible to distribute the heat more evenly over the outer surface of the preform, and thus to obtain a thermoformed rod having a more regular shape, and to reinforce the connection when the hot-melt portion (s) is / are used to secure one or more functional component (s) with the first and / or the second knitted tubular part (s), and / or, the first and second tubular parts knitted together. The preform comprises a sole part (intended to come into contact with the sole part of the envelope defined below), a lateral part (intended to come into contact with the lateral side of the envelope defined below) , a medial part (intended to come into contact with the medial side of the envelope defined below), a front part in the extension of the medial, lateral and sole parts (intended to cover the front of the foot of the envelope defined below), and a rear part in the extension of the medial, lateral and sole parts (intended to cover the rear of the foot, and therefore the heel, and possibly the ankle of the envelope defined below) .

In a preferred embodiment, the preform comprises perforations in at least one of the aforementioned parts, in particular in each of the aforementioned parts.

Preferably, the preform comprises perforations distributed over the entire exterior surface of the preform, in particular intended to come into contact with the footwear assembly.

Preferably, the preform is hollow and comprises an interior volume, and the perforations are through openings opening onto the exterior surface of the preform, and into the interior volume, in particular onto the interior surface of the preform.

Preferably, the perforations comprise substantially circular perforations.

In a preferred embodiment, the perforations comprise (or consist of) perforations whose largest dimension is circumscribed in a circle whose diameter is greater than 1 mm, more preferably greater than or equal to 3 mm, preferably greater than or equal to equal to 6 mm, in particular less than or equal to 20 mm, in particular less than or equal to 10 mm.

In one embodiment, the ratio of the sum of the areas (cm ² ) of the perforations to the total area of the exterior surface (cm ² ) of the preform is less than or equal to 60%, preferably less than or equal to 40% , more preferably less than or equal to 25%, in particular greater than or equal to 10%.

The heat in fact circulates through the footwear assembly but also through the perforations of the preform towards its interior volume, and conversely from its interior volume, through the perforations towards the footwear assembly.

In a variant, the outer surface of the preform comprises at least one metal, in particular stainless steel, aluminum, iron, or a combination of the latter.

In one embodiment, the preform, in particular its outer surface, comprises / (essentially consists) of at least one metal or a metal alloy, whether ferrous or not. ferrous, in particular is chosen from: stainless steel, iron, aluminum, or a combination of these.

In particular, the entire exterior surface of the preform comprises at least one metal or one metal alloy.

In a variant, the outer surface of the preform comprises a glass-ceramic material, in particular the outer surface of the preform is made of a glass-ceramic material.

In one variant, the preform, in particular its outer surface, undergoes a physical and / or chemical surface treatment.

This arrangement makes it possible to give the preform one or more additional thermal and / or mechanical property (s), in particular to improve the properties of resistance to corrosion, wear or impact, which optimize the use of the preform.

This arrangement advantageously makes it possible to reduce the time of step (iii) very significantly.

In the state of the art, when the thermoforming is carried out separately from the joining step using a plastic preform, the thermoforming time is of the order of 1 minute 20 seconds. The inventors have observed that this time is halved using a metal preform without altering the footwear assembly.

Brief description of the drawings

The invention will be better understood on reading the following description of embodiments of the invention given by way of non-limiting example, with reference to the appended drawings, in which:

[Fig. 1] Figure 1 illustrates a first example of a knitted tubular component comprising first and second knitted tubular portions;

[Fig. 2] FIG. 2 illustrates a second example of a knitted tubular component comprising first and second knitted tubular parts;

[Fig. 3] FIG. 3 represents a first example of a footwear assembly arranged on a preform in the form of a foot;

[Fig. 4] FIG. 4 represents the footwear assembly of FIG. 3 placed on a preform placed in a molding volume for carrying out the transformation step (iii);

[Fig. 5] FIG. 5 illustrates an example of an article of footwear comprising an upper obtained at the end of the transformation step (iii); and

[Fig. 6] FIG. 6 illustrates a first example of a rod obtained after transformation step (iii). Description of embodiments

FIG. 1 shows a first example of a knitted tubular component 10 in one piece 15, comprising a first knitted tubular portion 20 and a second knitted tubular portion 30, each of which is angled. The knitted tubular component 10 thus has a substantially U-shape. The first and second knitted tubular pieces 20,30 are of unitary knitted construction with the knitted tubular component 10. The first knitted tubular portion 20 includes an open distal end 22, which will be unitary. preferably closed by stitching before placing on the preform, and an open proximal end 24 delimiting a zone for introducing the foot 26 as well as a reception volume 28 for the foot. The second knitted tubular part 30 comprises a distal end 32 closed during knitting of the tubular component 10, and an open proximal end 34 delimiting a zone for introducing the foot 36 as well as a reception volume 38 for the foot. Preferably, the first and second knitted tubular portions 20,30 comprise respective heel areas 25,35 for receiving the heel of the user's foot. It is determined, when programming the knitting machine to knit the knitted tubular component 10, the zoning of the first and second knitted tubular parts 20,30 according to different stitch patterns (purl stockinette, knit stockinette, ribbed stitches, ... ) and different types of threads (by their nature and / or their color and / or their transparency and / or their title (dtex)). It is thus possible to vary the relief, the thickness, the aesthetics, and the functionality of the determined zone (s), and this for the first knitted tubular part 20 and the second knitted tubular part 30, independently of 'from each other.

Alternatively, only one of the first and second tubular portions 20 and 30 may include an elbow portion such that the tubular component 10 has a general L-shape.

The first knitted tubular part 20 comprises threads at least in part thermofusible arranged in one or more portions. The second knitted tubular part 30 may also include one or more hot-melt portions formed of at least partially hot-melt yarns. The at least partly thermofusible yarns represent, for example at least 30% by mass, and at most 60% by mass, of the total mass of the first knitted tubular part, and are distributed over the entire latter. The at least partially thermofusible yarns represent, for example at least 50% by mass, and at most 80% by mass, of the total mass of the second knitted tubular part, and are distributed over the entire latter. This arrangement can of course vary depending on the stability and flexibility sought. The second exemplary knitted tubular component 100 shown in FIG. 2 is also in one piece 150, and comprises first and second knitted tubular portions 200 and 300. The knitted tubular component 100 is substantially straight, the first and second tubular portions 200. and 300 not including angled portions. FIG. 3 represents a first example of a footwear assembly 40 placed on a preform 50 in the shape of a foot. The footwear assembly 40 comprises the knitted tubular component 10 shown in FIG. 1. The second tubular part 30 is arranged in the volume accommodating the foot 28 of the first tubular part 20 so that the first and second tubular parts 20 and 30 are superimposed.

The footwear assembly 40 also includes a functional component 60 which is a heel reinforcement and a functional component 70 which is an instep cushioning element. The functional components 60 and 70 are disposed between the first and second knitted tubular portions 20 and 30, respectively between the forefoot portions and the rearfoot portions at the heel. The functional component 60 extends vertically from the longitudinal axis L. The knitted tubular parts 20 and 30 thus form, respectively, an outer layer 80 and an inner layer 90 of the rod 400 obtained after the transformation step ( iii) and shown in Figure 6. The footwear assembly 40 also comprises a functional component 75 which is a polymeric film, for example hot-melt polyurethane, and whose dimensions are determined so as to cover at least 50% of the outer surface. 21, in particular the entire outer surface 21, of the first knitted tubular part 20, with the exception of the sole part 27. The forming step (ii) of the footwear assembly 40 can be carried out after the component tubular 10 placed on the preform 50 or before the placement of the tubular component 10 on the preform 50. The footwear assembly 40 of FIG. 4 placed on the preform 50 is then placed in a molding volume defined between a mold The outer 500 in two parts 510,520 shown in Figure 4 and the preform 50. The parts 510 and 520 define a foot-shaped volume complementary to the foot shape of the preform 50. Alternatively, the molding volume can be also delimited between the outer surface of the preform 50 and a waterproof flexible membrane, comprising a hollow shape substantially of a foot mating the footwear assembly disposed on the preform 50. The footwear assembly 40 can then undergo a transformation step (iii) for obtaining an upper 400 comprising the thermoforming of the footwear assembly 40 according to the foot shape of the preform 50, and the securing of the functional components 60,70 to the first and second knitted tubular parts 20,30, of the functional component 75 to the first knitted tubular portion 20, and first and second knitted tubular portions 20 and 30 at least in part to each other. In particular, the internal surface 23 of the first knitted tubular part is placed directly against the external surface 31 of the second knitted tubular part 30. The thermoforming and the joining take place in a single step, and therefore at the same time. Heat, water vapor and evacuation are thus applied to the footwear assembly 40 so as to press the footwear assembly 40, therefore including the functional components 60, 70 and 75 against the outer surface. 51 of the preform 50. The evacuation of the molding volume makes it possible to press the footwear assembly 40 against the outer surface 51, in particular the functional component 75 thus perfectly matching the outer surface 21 of the first knitted tubular part 20. The functional component 75 being thermofusible, it is secured to the outer surface 21 of the first tubular 20. The functional components 60 and 75 adhere to the first and second tubular parts 20 and 30 by means of the hot-melt portions which they comprise and / or by means of hot-melt portions supported by the functional components 60 and 75 themselves, and / or by means of adhesive (s), optionally hot-melt (s). The rod 400 shown in Figure 6 comprises the functional components 60, 70 and 75 perfectly integrated, secured and shaped to the shape of the foot of the preform 50. It is not necessary to go through a step of laying flat. of the first knitted tubular part 20. It is thus possible to functionalize all of the outer or inner surfaces of the first and second tubular parts 20 and 30, without limiting the size of the functional components. Furthermore, the joining of the functional components and the thermoforming of the footwear assembly 10 taking place at the same time, the functional components are not thermally degraded.

The sole part 450 of the upper 400 is then secured to a sole element 500 to obtain the article of footwear 1 shown in FIG. 5. The upper 400 can thus comprise different knitted zones 401 to 406 for the first part. tubular knitted 20 which appear under the transparent coating 78 resulting from the transformation of the film 75. The zones 401 to 406 differ in terms of their mesh patterns, their colors, their elasticities, or their rigidities. The zones 406 thus correspond to knitted unidirectional reinforcing elements reinforcing the medial and lateral parts of the upper 400.

Claims

1. A method of manufacturing an article of footwear (1) comprising the steps of:

(i) - providing a first knitted tubular part (20) comprising at least one hot-melt portion, and one or more functional component (s) (60; 70; 75);

(ii) - forming a footwear assembly (40) comprising the first knitted tubular part (20), and one or more functional component (s) (60; 70; 75);

(iii) - transforming the footwear assembly (40), placed on a preform in the form of a foot (50), into a rod, the transformation step comprises:

- thermoforming of the footwear assembly (40) according to the foot shape of the preform (50), and

- the at least partial joining of the functional component (s) (60; 70; 75) to the first knitted tubular part (20), and

in that the thermoforming and the securing take place in a single step comprising a vacuum of the footwear assembly (40).

2. Method according to claim 1, characterized in that during step (iii) of transformation, is applied, in a single step, to the footwear assembly (40), in combination with heat, a flow of gas (s), in particular water vapor.

3. Method according to either of claims 1 and 2, characterized in that it comprises providing a second knitted tubular part (30), optionally comprising at least one hot-melt portion, and in that the The footwear assembly (40) in step (ii) comprises the first and second knitted tubular parts (20; 30), at least in part, superimposed, in conjunction with one or more functional component (s) (60 ; 70; 75).

4. Method according to claim 3, characterized in that the joining, in step (iii) allows the joining, at least partially:

- first and second tubular parts knitted together (20; 30), and

- optionally one or more functional component (s) (60; 70; 75) to the second knitted tubular part (30).

5. Manufacturing process according to either of claims 3 and 4, characterized in that it comprises the provision of a knitted tubular component (10), and in that the first knitted tubular part (20) and the second knitted tubular portion (30) are of unitary knitted construction with the knitted tubular component (10) so as to form a one-piece knitted member (15).

6. The manufacturing method according to any one of claims 3 to 5, characterized in that it comprises the provision of at least one functional component (60; 70) between the first knitted tubular part (20) and the second part. tubular knitted (30), in particular during step (ii) and / or during step (iii).

7. The manufacturing method according to any one of claims 3 to 6, characterized in that the first knitted tubular part (20) forms an outer layer (80) of the rod (400) and the second knitted tubular part (30) forms an inner layer (90) of the rod (400).

8. Manufacturing process according to any one of claims 3 to 7, characterized in that the first knitted tubular part (20) comprises an opening zone for introducing the foot (26) and the second knitted tubular part (30). ) comprises a foot opening opening zone (36), said foot opening introduction zones (26; 36) are superimposed.

9. The manufacturing method according to any one of claims 3 to 8, characterized in that the second knitted tubular part (30) comprises one or more yarn (s) at least partly hot-melt (s), the mass ratio of the yarn (s) at least partly hot-melt (s) over the total mass of the second knitted tubular part (30), is less than or equal to 80%, preferably less than or equal to 60%, more preferably is less than or equal to 40%, in particular less than or equal to 20%.

10. The manufacturing method according to any one of claims 1 to 9, characterized in that at least one of the functional component (s) is a polymeric film (75), at least partly thermofusible.

11. The manufacturing method according to claim 10, characterized in that after step (iii), said film (75) forms a coating (78) covering at least 50%, preferably at least 70%, of the outer surface. of the rod (400).

12. The manufacturing method according to any one of claims 1 to 11, characterized in that the first knitted tubular part (20) comprises one or more yarn (s) at least partly hot-melt (s), the mass ratio of the yarn (s) at least partly thermofusible over the total mass of the first knitted tubular part (20), is greater than or equal to 20%, preferably greater than or equal to 40%, more preferably greater or equal to 60%, in particular greater than or equal to 80%.

13. The manufacturing method according to any one of claims 1 to 12, characterized in that at least one or more functional component (s) is chosen from: a polymeric film at least partly thermofusible, a heel reinforcement element, a logo, an aesthetic element, a hard toe, a lacing zone reinforcement element, a cushioning element, an auxiliary knitted tubular part, or a combination thereof.

14. Method according to any one of claims 1 to 13, characterized in that step (iii) comprises heating the preform to a heating temperature greater than or equal to Tp, with Tp> T1, Tl being greater or equal to the melting or softening temperature of said at least one hot-melt portion.

15. Method according to any one of claims 1 to 14, characterized in that step (iii) comprises heating a molding volume to a heating temperature greater than or equal to Tvm, with Tvm> T1, Tl being greater than or equal to the melting or softening temperature of said at least one hot-melt portion.

16. Method according to any one of claims 1 to 15, characterized in that the upper (400) obtained in step (iii) comprises a sole portion (450), and in that said method comprises a step of attachment of at least one sole element (500) selected from an intermediate sole, and an outsole to said sole portion of the upper.

17. Method according to any one of claims 1 to 16, characterized in that the preform comprises an internal volume and perforations opening onto its external surface, said internal volume and the perforations are in fluid connection.