Method for the three-dimensional forming of an upper of a footwear

Abstract

A method for the three-dimensional forming of an upper of a footwear, comprises: preparing a sock comprising thermoplastic yarns; fitting the sock on a reference form of an upper to be formed; placing the reference form with the sock in an oven; heating the sock in the oven up to determining the at least partial fusion of thermoplastic material of the thermoplastic yarns of the sock; cooling the sock up to determining the cross-linking of the thermoplastic material and the formation of the upper with more rigid portions and less rigid portions; removing the upper from the reference form.

Claims

1. A method for three-dimensional forming of an upper of a footwear, comprising: preparing a sock comprising thermoplastic yarns, the sock further comprising an inner sock and an outer sock mutually joined at an ankle area, wherein the inner sock is configured to be placed inside the outer sock to form a double layer and the inner sock and the outer sock have respective auxiliary openings obtained from a weaving step of the sock; closing the auxiliary opening of the outer sock; arranging accessory elements on a reference form of an upper to be formed; fitting only the outer sock onto the reference form by inserting the reference form through the auxiliary opening of the inner sock while the inner sock is arranged outside the outer sock; placing the reference form with the sock in at least one oven; heating the sock in the oven up until a determination of at least partial fusion of thermoplastic material of the thermoplastic yarns of said sock; cooling the sock up until a determination of a cross-linking of the thermoplastic material and a formation of the upper with more rigid portions and less rigid portions; and removing the upper from the reference form; wherein heating the sock in the oven comprises circulating a superheated steam in the oven.

2. The method according to claim 1, wherein circulating the superheated steam comprises forming a mixture of air and steam.

3. The method according to claim 1, wherein cooling the sock comprises removing the reference form with the sock from the oven and placing it in a cooling chamber, and circulating cooled air in the cooling chamber.

4. The method according to claim 1, wherein the sock has a main opening configured to insert a foot and at least one auxiliary opening obtained from a weaving step of said sock; wherein the method further comprises closing the auxiliary opening and then fitting the sock on the reference form; wherein closing the auxiliary opening comprises cutting edges of the auxiliary opening and at the same time sealing said auxiliary opening by means of ultrasounds.

5. The method according to claim 1, wherein, after the cross-linking of the thermoplastic material, the method further comprises joining the inner sock to the outer sock in one or more areas of the upper.

6. The method according to claim 1, comprising arranging accessory elements on the reference form, fitting the sock onto the reference form, joining points of said accessory elements to the sock and then arranging the reference form with the sock in the oven; wherein joining points of said accessory elements to the sock comprises determining fusion of points of the thermoplastic material of the thermoplastic yarns of said sock and/or of the accessory elements through a localized heating.

7. The method according to claim 1, comprising fitting the sock on the reference form, and arranging accessory elements on the sock, joining points of said accessory elements to the sock and then placing the reference form with the sock in the oven; wherein joining points of said accessory elements to the sock comprises determining fusion of points of the thermoplastic material of the thermoplastic yarns of said sock and/or of the accessory elements through localized heating.

8. The method according to claim 1, comprising joining points of said accessory elements to the outer sock while only the outer sock is fitted on the reference form; wherein joining points of said accessory elements to the outer sock comprises determining fusion of points of the thermoplastic material of the thermoplastic yarns of said outer sock and/or of the accessory elements through localized heating.

9. The method according to claim 8, comprising removing the reference form from the outer sock and the inner sock through the auxiliary opening of the inner sock, closing the auxiliary opening of the inner sock, placing the inner sock inside the outer sock, fitting the inner sock and the outer sock on the reference form through the main opening, arranging the reference form with the sock in the oven.

10. The method according to claim 1, comprising inserting the reference form with the sock in a heat-resistant bag and placing the heat-resistant bag under vacuum, reducing an internal pressure of the heat-resistant bag to a pressure below an atmospheric pressure; wherein the reference form with the sock is removed from the heat-resistant bag after cooling and cross-linking the thermoplastic material.

11. The method according to claim 1, wherein a temperature of the superheated steam is between 150? C. and 200? C.

12. The method according to claim 2, wherein, in the mixture, a temperature of the air is between 50? C. and 300? C. and a temperature of the steam is 100? C.

13. The method according to claim 2, wherein the steam for the mixture is already superheated at a temperature between 150? C. and 200? C.

14. The method according to claim 2, wherein a percentage of air in the mixture is between 10% and 70%.

Description

DESCRIPTION OF THE DRAWINGS

(1) Such description will be outlined hereinafter with reference to the attached drawings, provided solely for by way of non-limiting example, wherein:

(2) FIG. 1 illustrates a footwear obtained with the process, with the method and with the apparatus according to the present invention;

(3) FIG. 2 illustrates a reference form of an upper to be formed, used in the method according to the present invention;

(4) FIG. 3 shows an embodiment of the sock comprising thermoplastic yarns used in the method according to the present invention;

(5) FIG. 4 illustrates the sock of FIG. 3 in a different configuration;

(6) FIG. 5 illustrates reinforcement elements to be applied to the sock according to the method of the present invention;

(7) FIG. 6 illustrates the reference form on which the reinforcement elements are applied according to a step of the method of the present invention;

(8) FIG. 7 illustrates a sock during a step of the method according to the present invention;

(9) FIGS. 8, 9 and 10 illustrated the reference form with the sock of the second embodiment in respective steps of the method of the present invention;

(10) FIG. 11 illustrates the reference form with the sock arranged in an oven according to a further step of the method of the present invention;

(11) FIG. 12 illustrates the reference form with the sock arranged in a cooling chamber according to a further step of the method of the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

(12) With reference to FIG. 1, a footwear obtained through the process, the method and the apparatus according to the present invention, was indicated in its entirety with 1.

(13) The footwear 1 comprises an upper 2 and a sole 3. As specified above, the upper 2 wraps the foot and comprises both the upper part of the footwear 1most exposed and visiblewhich covers the top part of the foot as well as the lower part, or insole, intended to remain concealed between the upper part and the sole 3 of the footwear 1.

(14) The upper 2 is formed starting from a sock 4 and possibly from other elements as specified hereinafter.

(15) The sock 4 is obtained by means of weaving, for example using a knitting loom of the circular type, of per se known type and thus not described herein.

(16) The sock 4 comprises natural and/or synthetic yarns and it is also provided with thermoplastic yarns, i.e. yarns formed by thermoplastic polymers (heat-fusible and/or heat-shrinking) which have the capacity to modify the structure thereof at a determined temperature (usually comprised between 60? C. and 180? C.) and thus fuse upon reaching such temperature and cross-link once cooled.

(17) The thermoplastic yarns are arranged in different manners and with different densities and percentages during weaving. For example, the percentage of the thermoplastic yarns is higher at the tip and/or at the heel and/or at the insole of the upper 2 and lesser elsewhere. For example, at the tip and at the heel the percentage of thermoplastic yarns is comprised between 20% and 80%. For example, at the insole the percentage of thermoplastic yarns is comprised between 50% and 60%.

(18) The arrangement and/or characteristics of the thermoplastic yarns allow to obtain consistencies and/or rigidities differentiated in terms of different areas/portions/points of the upper 2 obtained through the method of the invention.

(19) According to a first embodiment, illustrated in FIGS. 3 and 4, the sock 4 is formed by two layers and comprises a first sock 5, or outer sock, and a second sock 6, or inner sock, mutually joined at, for example, an area designated to be positioned around an ankle 5A of a user. The inner sock 6 and the outer sock 5 are woven in a single weaving step. At the end of the weaving, the inner sock 5 and the outer sock 6 are mutually joined in said ankle area 5A and consecutively arranged one with respect to the other to form a single tubular body provided with two auxiliary openings 8, 9 arranged at the opposite ends thereof, as illustrated in FIG. 4. The inner sock 6 can be turned inside-out and positioned inside the outer sock 5 to form a double-layer sock 4, as illustrated in FIG. 3.

(20) When the inner sock 6 is turned inside-out and inserted into the outer sock 5, the sock 4as a wholehas a main opening 7 configured to allow to insert a foot and for defining, for example, the portion of the upper 2 arranged around the ankle of the person who is wearing it. The outer sock 5 has its own auxiliary opening 8 arranged on an end/tip thereof and even the inner sock 6 has an auxiliary opening 9 thereof arranged on an end/tip thereof. The auxiliary openings 8, 9 are obtained from the weaving processing of said sock 4, in the sense that the loom for the knitting machine of the circular type used to make it does not envisage closing them. One or both of the auxiliary openings 8, 9 have unfinished and frayed edges. As will be clearer hereinafter, the auxiliary opening 9 of the inner sock 6 is preferably utilised in the method according to the invention.

(21) According to a simpler second embodiment, the sock 4 is formed by a single layer which corresponds to the outer sock of FIGS. 3 and 4 only (i.e. it is not provided with the inner sock 6). In such embodiment, the sock 4 has the main opening 7, which is shaped and configured to allow to insert the foot and to define, for example, the portion of the upper 2 arranged around the ankle, and an auxiliary opening 8 arranged at the tip of the sock 4. The auxiliary opening 8 is obtained from the weaving processing of said sock 4, in the sense that the loom for the knitting machine of the circular type used to make it does not envisage closing it. Thus, the auxiliary opening 8 has unfinished and frayed edges. The main opening 7 is instead preferably finished.

(22) Described hereinafter is the method in its entirety which uses the sock 4 of the first embodiment alongside other accessory elements.

(23) According to the method of the invention, a reference form 10 which reproduces the upper 2 to be formed in negative (FIG. 2) is prepared. The reference form 10 is made of plastic material and it is such to be able to withstand high temperatures and pressure without deteriorating and/or deforming. The reference form 10 substantially reproduces the shape of a foot and it is provided, at the ankle, with anchoring elements 11 (schematised as holes) for the engagement with a support 12, illustrated in FIG. 11.

(24) Besides the sock 4, a reinforcement structure 13 which, in the non-limiting embodiment illustrated in FIG. 5, comprises a reinforcement for the insole 14, a reinforcement for the tip 15 and a reinforcement for the heel 16 is made in advance. The reinforcement structure 13 is also preferably made of plastic material or it comprises plastic material or it has one side with a heat-adhesive agent.

(25) Furthermore, an impermeable membrane, not illustrated in the attached figures, with a shape similar to that of the outer sock 5, can be prepared and used. The impermeable membrane is for example polyurethane.

(26) The method provides for fitting the reinforcement structure 13 on the reference form 10 first, like in FIG. 5, and then the impermeable membrane and then fitting the outer sock 5 only on the reference form 10 and above the impermeable membrane and the reinforcement structure 13 (FIG. 8).

(27) To this end, before fitting the outer sock 5, the auxiliary opening 8 of the outer sock 5 is closed by cutting the edges thereof and sealing it by means of the ultrasonic cutting and sealing carried out simultaneously by means of an ultrasonic cutting and sealing machine (FIG. 7), per se known and thus just described summarily.

(28) The ultrasonic machine, schematically illustrated in FIG. 7, comprises: a lower wheel 17 which rotates around a horizontal rotation axis X; a sonotrode 18 connected to the lower wheel 17 to determine an ultrasonic vibration according to a vertical direction; an upper wheel 19 which rotates around a horizontal rotation axis Y and it has a tapered edge which touches the lower wheel 17 and which generates heat locally due to the vibration. The localised heat cuts and, exploiting the thermo-plasticity of the yarns, fuses and seals them. During cutting and sealing, the ultrasonic machine also allows to carry out the shaping of the tip of the sock. By way of example, FIGS. 8, 9 and 10 illustrate a sealing line 20. Actually, the cutting and sealing through ultrasonic means allow to close the tip almost invisible, without parts in relief which could be uncomfortable for the person wearing the footwear 1.

(29) Alternatively, the auxiliary opening 8 of the outer sock 5 can be cut and closed by means of a cutting and sewing, with a less prestigious aesthetic technical effect. At this point, the reference form 10 is inserted into the sock 4 through the auxiliary opening 9 of the inner sock 6 up to fitting the outer sock 5 only on the reference form 10 and leaving the inner sock 6 outside the outer sock 5 and hanging onto said outer sock 5 (FIG. 8).

(30) While only the outer sock 5 is arranged on the reference form 10 and around the impermeable membrane and the reinforcement structure 13, the method envisages joining some points of the outer sock 5 to corresponding points of the reinforcement structure 13 and of the impermeable membrane by means of a localised heating, carried out by an electric stapler with a suitably shaped iron box, configured for determining the fusion of areas of the thermoplastic material of the thermoplastic yarns of the outer sock 5 and of the thermoplastic material of the reinforcement structure 13 and of the impermeable membrane. The joining by points serves to temporarily stabilise the assembly before a subsequent heating in an oven that will determine the stable joining of all elements.

(31) Once through with joining by points, the reference form 10 is removed through the auxiliary opening 9 of the sock 4. Such auxiliary opening 9 of the inner sock 6 is also closed, for example, by cutting and sealing, as specified above. The inner sock 6 is inserted, turning it inside-out, into the outer sock 5 and fitted onto the reference form 10 which is inserted through the main opening 7 this time round. Thus, the reinforcement structure 13 and the impermeable membrane remain interposed between the inner sock 6 and the outer sock 5 and the inner sock is at direct contact with the reference form 10 (like in FIG. 9).

(32) At this point, applied onto the outer sock 5 are decorative elements 21 (FIG. 10), for example in form of sheets and/or coloured patches with one side provided with a heat-adhesive agent, and temporarily joined to the outer sock 5 also through resistance welding. Any further reinforcement elements, not illustrated, can also be applied to the external of the outer sock 5.

(33) The overall assembly formed by the reference form 10, by the inner sock 6, by the outer sock 5, by the reinforcement structure 13, by the impermeable membrane and by the decorative elements 21 is inserted into a heat-resistant plastic bag 22 which is connected to a vacuum device, not illustrated. The vacuum device removes the air contained in the heat-resistant bag 22 so as to reduce the internal pressure to below the atmospheric pressure and compress and hold in position all the elements on the reference form 10. For example, the vacuum in the bag 22 is of about ?85 kPa so as to exert a pressure in the sock 4 of about 850 g/cm.sup.2.

(34) The assembly (reference form 10, inner sock 6, outer sock 5, reinforcement structure 13, impermeable membrane, decorative elements 21) with the bag 22 under vacuum is inserted into an oven 23.

(35) The oven, illustrated in FIG. 11, comprises an outer casing 24 and an inner casing 25. The inner casing 25 delimits a containment volume designated to receive the assembly with the bag 22 under vacuum. The inner casing 25 and the outer casing 24 delimit an interspace 26 between them. The inner casing 25 is also provided with passage holes 27 which place the interspace 26 in communication with the containment volume.

(36) A fan 28 is mounted on the outer casing 24 and on the inner casing 25 and it has a main mouth 29 facing in the containment volume and radially peripheral outlets which open into the interspace 26. The fan 28 is thus operatively active between the containment volume and the interspace 26 to determine the circulation of fluid between said containment volume and said interspace 26. The fan 28 suctions the fluid through the main mouth 29 and blows it into the interspace 26 and from here into the containment volume once again through the passage holes 27.

(37) Heating electrical resistors 30, schematically illustrated in FIG. 11, are arranged in the interspace 26 and suitably power-supplied and controlled to heat the fluid circulating in the oven 23. The oven 23 is also provided with nozzles 31 facing into the interspace 26 and connected to a steam generation device, preferably superheated, not illustrated, configured to introduce steam into the oven 23.

(38) The assembly with the bag 22 is positioned in the oven 23 by means of the support 12 which holds it hanging in the containment volume, i.e. spaced from internal walls of the oven 23. The support 12 is connected to devices, not illustrated, configured for rotating the support 12 and the assembly with the bag 22 around an axis Z.

(39) The oven 23 is configured to circulatethereina fluid consisting of superheated air and steam, preferably superheated, which touches the bag 22 and uniformly heats the assembly (reference form 10, inner sock 6, outer sock 5, reinforcement structure 13, impermeable membrane, decorative elements 21) while the latter rotates on itself around the axis Z. The heating causes the at least partial fusion of the thermoplastic material of the thermoplastic yarns of the outer sock 5, possibly of those of the inner sock 6, of the reinforcement structure 13, of the impermeable membrane and of the decorative elements 21.

(40) For example, the percentage of superheated air in the superheated air and steam mixture is between 10% and 70%; the temperature of the superheated air is between 50? and 300? C.; the temperature of the superheated steam is between 150? C. and 200? C.; the pressure inside the oven is 0.1 bars. In this manner, the assembly (reference form 10, inner sock 6, outer sock 5, reinforcement structure 13, impermeable membrane, decorative elements 21) is brought to a temperature between 50? and 300? C. for a period of time between 10 and 300 sec.

(41) In variant embodiments, not described in detail, instead of the mixture of superheated air and steam, the following can be used for heating: superheated air only, steam only, preferably superheated, radiation with infrared rays only, combination of infrared rays and superheated air.

(42) In variant embodiments, not described in detail, it is envisaged to carry out a first heating of the sock 4 in a first oven, preferably by means of superheated air and steam, for pre-heating the sock 4, and carry out a second heating of the sock 4 in a second oven, preferably by means of superheated air and steam for determining the at least partial fusion of the thermoplastic material of the thermoplastic yarns of said sock 4.

(43) Subsequently, the assembly still wrapped in the vacuum bag 22 is removed from the oven 23 and inserted into a cooling chamber 32 (schematically illustrated in FIG. 12) circulated in which is cooled air, for example at a temperature between ?10? and +10?, so as to cool the assembly up to the ambient temperature.

(44) The cooling determines the cross-linking and the hardening of the thermoplastic material, the formation of the upper 2 with more rigid portions and less rigid portions, the mutual and stable joining of the outer sock 5 with the reinforcement structure 13, with the impermeable membrane and with the decorative elements 21. As a function of the distribution of the thermoplastic yarns in the outer sock 5 and/or in the inner sock 6, after cross-linking the thermoplastic material, the inner sock 6 can be joined to the outer sock 5, as well as at the ankle area, even in one or more areas of the upper 2, so that it cannot be removed from said outer sock 5, or it is free to be removed from said outer sock 5, i.e. it is joined to the outer sock 5 only at the ankle area 5A.

(45) The reference form 10 with the assembly are removed from the heat-resistant bag 22 after the cooling and cross-linking of the thermoplastic material, i.e. when the assembly is stabilised. The heat-resistant bag 22 is preferably internally coated with a film that facilitates the detachment thereof from the sock after the cooling and cross-linking of the thermoplastic material.

(46) At this point, the upper 2 can be removed from the reference form 10 to subject it to further processing.

(47) For example, according to the manufacturing process of a footwear according to the present invention, it is envisaged to apply the sole 3 to the upper 2 so as to obtain the footwear 1 of FIG. 1.

(48) Simpler embodiments of the method are equally part of the present invention.

(49) According to a first variant of the method which does not envisage the reinforcement structure, the decorative elements and the impermeable membrane but comprise the sock 4 only (of the single or double layer part), it is envisaged to close the auxiliary opening or the auxiliary openings 8, 9, fit the sock 4 on the reference form 10 and introduce such assembly into the oven 23 without any heat-resistant bag (given that it is not required) and then cooling it in the cooling chamber 32.

(50) A second variant of the method envisages the reinforcement structure 13, the decorative elements 21 and the impermeable membrane but it comprises the outer sock 5 only (single-layer sock 4). In this variant, it is envisaged to close the auxiliary opening 8, fit the reinforcement structure 13 and then the impermeable membrane onto the reference form 10, fit the sock 4 onto the reference form 10 and above the impermeable membrane and the reinforcement structure 13, apply the decorative elements 21 onto the outer sock 5, temporarily join the reinforcement structure 13 and the decorative elements 21 to the sock 4 through electric resistance welding, introduce the assembly into the heat-resistant bag 22. The assembly with the heat-resistant bag 22 are then introduced into the oven 23 and then into the cooling chamber 32.

(51) In other variants, not illustrated, the impermeable membrane is applied outside the sock 4, preferably when the upper has already been formed, and in this case said membrane can also carry the decorative elements.

(52) The oven 23, the cooling chamber 32, the ultrasonic cutting and sealing machine, the electric stapler, the vacuum device are part of an apparatus for the three-dimensional forming of an upper of a footwear, also according to the present invention.