EP1996393A1

EP1996393A1 - Method of making a footwear by injection/casting of a mono-or multi-layered sole of synthetic material directing onto the upper

Info

Publication number: EP1996393A1
Application number: EP06745243A
Authority: EP
Inventors: Ettore Bordin
Original assignee: STEMMA SRL
Current assignee: STEMMA SRL
Priority date: 2006-03-22
Filing date: 2006-03-22
Publication date: 2008-12-03
Also published as: WO2007108024A1

Abstract

Method for the production, by means of injection/casting directly onto an upper (32), of a shoe formed at least by one sole part (50; 79) and an upper (32), where the former overlaps in an overlapping area (53) the toe (40) and/or the heel of the latter. The upper (32) is enclosed inside a first mould (36) which grips it at the edges leaving at least one zone (39) of the toe (40) and/or the heel thereof exposed and which defines a first cavity (49; 81) where the sole is formed. A second mould (46; 72) in the form of a single-piece block comprising a second cavity (48, 74a, 74b) is coupled to the first mould (36) so as to form the first cavity (49; 81) and so as to introduce the exposed zone (39) of the upper (32) into the second cavity (48, 74a, 74b). A mould and a machine as well as the shoes which may be made with them are also claimed.

Description

"Method of making a footwear by injection/casting of a mono-or multi-layered sole of synthetic material directing onto the upper "

DESCRIPTION

The present invention relates to a process for the production of shoes with a single-layer or multiple-layer sole by means of injection/casting directly onto the upper, and to the means for implementing the process and the shoe obtained thereby. Many known types of shoes with a sole made of synthetic materials, usually- used for leisure activities (casual wear, jogging or trekking) and/or as work shoes, may^¬ be divided into two categories: shoes with a single-layer sole (type 1) or shoes with a multiple-layer sole (type 2).

The former, which are shown schematically in a mould 100 in Figs. 1 and 2 during and at the end of the moulding process respectively, generally have an upper 102 which is fitted onto a form 101 and intended to be joined to a sole 104 (referred to below as "sole or tread sole"). In some models, such as those shown, the tread sole 104 is in direct contact in an area 108 with the toe and/or the heel of the upper 102 and may, for functional or aesthetic reasons, project from the sole of the latter. The sole 104 therefore extends and/or covers outer zones at the horizontal end points of the upper 102 and partly surrounds the tip thereof - at the so-called toe end - and/or the heel. Basically, the upper 102 is not limited to the sole alone of the shoe. In order to simplify the following description the term "wrap-around" shall be used to describe this feature, while the expression "overlapping area or zone" will be used to describe the part of the upper projecting from its sole or midsole which is covered by the sole or midsole itself.

Shoes with a multiple-layer sole may be roughly divided into two subcategories: with a complete midsole (type 2a) or partial midsole (type 2b).

A shoe of the type 2a is shown in Fig. 3 inside a mould 200 and has an upper 202 fitted onto a form 201 and enclosed at the bottom by a tread sole 204. A middle piece 206, called a midsole, is situated between the sole 204 and the upper 202 and separates them over the whole surface of the tread sole which is thus never in direct contact with the upper 202. The midsole 206 may also have a wrap-around shape, as can be seen from Fig. 3.

A shoe of the type 2b is generally that where the tread sole is, in some zones, in direct contact with the upper without the presence of the midsole. An example of this type of shoe is shown in isolation in Fig. 4 and has an upper 302 underneath which there is a midsole 306 to which a tread sole 304 is attached. The midsole 306 is arranged between upper 302 and tread sole 34, except in an overlapping zone 308 where the tread sole 304 is in direct contact with the upper 302 and in some shoe models, such as that shown, covers part of the toe (or heel) thereof.

In this description "injection" is to be understood as meaning the introduction, via an injection hole, of plastic material in the fluid state inside a closed cavity, while "casting" is to be understood as meaning the introduction of plastic material in the fluid state inside an open cavity.

In the production of shoes with a sole made of materials injected or cast onto an upper according to the state of the art, the upper, which is suitably fitted onto a form, is inserted inside an injection/casting cavity 210 and plastic material 400 is introduced inside it, and, solidifying, adheres directly onto the said upper (see, for example, Figs. 1 and 2).

It is possible to obtain single-layer or multiple-layer soles using various processes, the most common of which consist in the steps of: a) injecting/casting the single-layer sole onto the upper; b) injecting/casting the midsole onto the upper, and then injecting/casting the tread sole onto the assembly consisting of these two elements; c) injecting/casting the tread sole separately from the upper; the upper and the sole are then fixed together by means of injection/casting of the midsole.

In the process according to case a), if performed by means of injection (two steps of which are shown in Figs. 1 and 2), the parts of the mould 100 consist of two side shells 120 (only one of which is shown in cross-section) and a base block 122.

The two shells 120 are moved towards each other so as to grip the form 101 and the upper 102, following which the material for forming the sole 104 is injected through an injection hole 130 (Fig. 1) onto the block 122. The block 122 is pressed towards the upper 102 so as to cause expansion of the material 400 injected/cast inside the shells

120 until the cavity 410 is filled and the sole 104 formed.

In the process according to case b) and c), of which only the final step is shown in Fig. 3 for the sake of simplicity, the parts of the mould 200 are identical to the case a) and indicated by the same reference numbers. The mould 200 differs owing to the presence of a second injection hole 420 necessary, for example, for injecting the material which forms the midsole 206 after the sole 204 has been cast and obtained, and owing to an additional mould part which acts so as to close the cavities which delimit the first zone to be injected.

For all these processes, if it is required to provide wrap-around soles or midsoles, moulds split into shells are always used, these shells, before injection, being closed around the form+upper assembly or the form+upper+part-already-moulded assembly.. In fact, as a result of the shell-type design of the moulds, it is possible not only to provide mould cavities corresponding to the overlapping zones but also extract the moulded article from the undercuts in the mould (after the two shells are separated), -which operation, if performed when the mould is closed, would require forcing which could damage the shoe. The division of the mould into several shells means that the typical lines/scoring created by joining together of the shells are present on the article.

With the said processes involving direct injection onto the upper, shoes which inevitably have the following characteristics are obtained: I) the toe end, or alternatively the heel, has a vertical line along the point where the mould half-shells are joined together and

II) the toe end, or alternatively the heel, has a transverse scoring line along the plane where the two mould half-shells and an additional block are joined together to form a mould cavity for the overlapping zones. These scoring lines on the sole and/or midsole detract from the appearance of the shoe, in particular if present on the most visible part.

Another method, involving direct injection onto the upper, for manufacturing wrap-around soles without scoring, requires the use of moulds made of deformable resins, the duration of which, however, is less than that of metallic moulds. It is therefore clear that in the prior art manufacturing shoes with a wraparound sole or midsole without the presence of lines requires processes different from the known direct moulding onto the upper.

The technical problem solved by the invention is to use the technology of injection, or casting, or spraying directly onto the upper, in order to provide shoes with a wrap-around single-layer or multiple-layer sole, in order to avoid the drawbacks of the known processes.

This object is achieved with a production method by means of the injection/casting directly onto the upper of a shoe formed at least by one sole part and an upper, where the former overlaps in an overlapping area the toe and/or the heel of the latter, and the upper is enclosed inside a first mould which grips it at the edges and which defines a first cavity where, once material has been introduced, the sole part is formed, characterized by forming the first mould so that it grips the upper, leaving at least one zone of the toe and/or the heel thereof exposed; providing a second mould in the form of a single-piece (monolithic) block comprising a second mould cavity with which the sole part is formed in the overlapping area; joining the first mould to the second mould in order to form the first cavity and so as to introduce the exposed zone of the upper inside the second cavity.

The method may be performed with a machine for producing by means of injection/casting directly onto the upper a shoe formed at least by one sole part and an upper, where the former overlaps in an overlapping area the toe and/or the heel of the latter, comprising a first mould which can be gripped around the edges of the upper and which defines a first cavity for forming the sole part following the introduction of material; a second mould which can be joined to the first mould and co-operates therewith so as to form the first cavity; characterized in that it comprises actuating/driving means for joining the first mould to the second mould by means of a relative rotary/translatory movement.

The said machine employs a mould which is characterized in that it is formed so as to grip the edges of the upper, leaving at least one zone of the toe and/or the heel thereof exposed and a mould characterized in that it comprises at least one additional mould cavity for forming the sole part in an area where the sole part and the upper overlap on the toe and/or on the heel of the upper.

The following description of the steps of a processing method according to the invention and a moulding machine for implementing said method is provided below solely byway of an example and with reference to the attached drawing where:

- Figures 1 to 4 shows schematically vertical sections through moulds and shoes in known processes;

- Figures 5 to 10 show, schematically, in vertically sectioned views, the sequence of steps of a first process according to the invention for manufacturing shoes of the type 1;

- Figures 11 to 17 show schematically, in vertically sectioned views, the sequence of steps for a second process according to the invention for manufacturing shoes of the type 2a;

- Figures 18 to 21 show some constructional details of the machine able to implement the method according to the invention.

With reference to Figures 5 to 10, the steps of a first process according to the invention for forming shoes of the type 1 are shown.

Fig. 5 (first step) shows an assembly 30 consisting of an upper 32 of a shoe fitted onto a form 34. The assembly 30 thus provided cooperates with a mould formed with two shells (or half-rings) 36, only one of which is shown in the cross- sections. All these parts, as well as the operations described for the latter and the following processes, are combined and managed by a moulding machine (the details of which are shown in Figures 18 to 21) which controls the movements thereof and the sequence of the various operating steps. It can be seen that Figures 18 to 21 show parts present in Figures 1 to 17 upside down, since according to a possible embodiment of the machine the shoe is formed with the sole directed upwards, in order to assist the operator during the step involving extraction from the shells 36. A machine according to the invention may be designed using parts of known moulding machines, such that only the characteristics components thereof are described and shown, and not details which are certainly known to the person skilled in the art.

The two shells 36 from an open position (Fig. 19) are gripped - position shown in Fig. 18 - around the bottom part of the upper 32 (see also Fig. 5). It should be noted that in Fig. 5, Fig. 18 and Fig. 19 the two shells 36 have internally projecting edges 38 which engage with the sides of the upper 32. These edges 38 and the inside of the shells 36 are formed in a known manner, also comprising an introduction hole 42 which allows the introduction of plastic material inside a mould cavity 44. The shells 36 - and this is a characteristic feature of the invention - with the edges 38 do not surround completely the upper 32, but terminate in a zone 39 of the toe 40 of the upper 32, leaving the toe 40 exposed.

Fig. 6 shows a following step. The assembly 30, which is gripped between the two shells 36, by means of actuating means of the machine described below, is joined to a mould die 46 with a relative rotary/translatory movement. A mould cavity 48 is formed in the upper surface of the die 46 and combines with the cavities formed by the edges 38 upon closing of the two shells 36 so as to form an overall cavity 49 (see Fig. 7) inside which plastic material is introduced via the hole 42 and a sole moulded In particular, the die 46 consists of a single piece (is monolithic) and comprises in a base block 47 a first mould cavity 48a, which defines the shape of a tread sole, and a second mould cavity 48b, formed in a block 51 projecting from the top of the block 47. The set of cavities 48a and 48b form the cavity 48.

In Fig. 6 the arrows F indicate a possible trajectory for joining together the shells 36 and the die 24, the outcome of this movement being essential, namely the introduction of the toe 40 of the upper 32 inside the cavity 48b (see Fig. 7, which shows the position of the parts at the end of the relative movement). It should be noted that a single linear movement would be unable to achieve the inserting movement described, here and below, but a rotary/translatory movement is required, namely a combination of at least one approach movement and at least one rotating movement in order to introduce the toe 40 into the cavity 48b.

At this point, after ensuring the stability of the relative position of the assembly 30 and the die 24, using known means the plastic material, for example polyurethane, is introduced through the hole 42, formed by joining together two opposite half-holes present in each of the two shells 36. The material fills the cavity 49 and forms a tread sole 50 of the shoe (Fig. 8). The finished shoe is shown in Fig. 10, after opening of the shells 36, the extraction of the assembly 30 from the die 46, for example performing a movement which is the reverse of that performed during the joining stage, and after removal of the form 34 from the upper 32.

As can be noted, the tread sole 50 has been injected onto the upper 32 and, in addition to forming the tread of the shoe (zone 51 in contact with the sole), extends over a part of the toe 39 of the upper 32 (overlapping area indicated by 53). It is clear that the cavity 48a in conjunction with the cavities 44 of the two shells 36 defines the shape of the tread, while the cavity 48b alone facing the toe 40 defines the extension and the form of the area 53 where upper 32 and tread sole 50 overlap. The process according to the invention, therefore, does not produces marks or scoring due to separation of the shells 36 on the front and visible part of the sole 50, limiting any presence of scoring lines to the side zone alone of the sole and to the rear zone. In fact the base block 47 consists of a single piece and does not have separating lines. In the case of multiple-layer soles of the type 2a, a second process is performed as follows. Reference should be made to Figures 11 to 17 and, also, to Figures 17 to 21, in which the same reference numbers are used for parts the same as those already described.

An assembly 30 (Fig. 11) consists of an upper 32 fitted onto a form 34. The assembly 30 cooperates with a mould formed with two shells 36.

Again the two shells 36 have edges 38 which are gripped around the bottom part of the upper 32 and now comprise two insertion holes 42, 43 which allow the introduction of plastic material inside a mould cavity 44.

As in the previous case, the edges 38 do not surround completely the upper 32.

A base piece 55 (see Fig. 12) is positioned underneath the upper 32 using known actuating means. The upper surface of the base piece 55 has, formed therein, a mould cavity 60 which cooperates with a part of the cavity 44 present in the shells so as to form an overall cavity into which, after the mould parts have been fixed in position, plastic material is introduced by means of injection or casting via the hole 42. The result of this injection/casting operation is shown in Fig. 13. The upper 32 has, associated with it, a midsole 62 which closes off the bottom thereof except for an area 68 at its tip 40, which remains exposed We shall refer to the upper 32 plus the midsole 62 thus obtained as "intermediate piece".

The process then envisages that the intermediate piece is gripped between the two shells 36 and the base piece 55 alone is removed, leaving visible the midsole 62. The intermediate piece thus gripped is joined to a mould die 72 for the sole with a relative movement which is similar to that described for the previous process.

Again the die 72 consists of a single piece and comprises in a base block 73 a first mould cavity 74a, which defines the form of a tread sole, and a second mould cavity 74b, which is formed in a block 76 projecting from the top of the block 73.

In this case the die 72 must be formed so as to correspond during closing with the two shells 36 and so that the block 73 occupies the volume previously occupied by the base piece 55 so as to define a tread sole 79 and so that the cavity 74b receives the toe 40 of the upper 32. The rotaiy/translatory movement for joining together the intermediate piece and the die 72, performed by means of actuating means of the machine described below, may take place for example as indicated by the arrows F in Fig. 14. It is basically necessary to obtain insertion of the toe 40 inside the cavity 74b and joining together of the edges 38 of the shells 36 and the die 72, in particular with the block 73. In this configuration overall a cavity 81 formed by combining the cavities 74a, 74b with those defined by the edges 38 is obtained in the mould

Using known injection means, a quantity of material, for example dual or multiple-component polyurethane, is then injected into the cavity 81 through the hole 43, so as to form the sole 79. During formation of the midsole 32, the hole 43 was closed by the base piece 55.

Fig. 16 shows the result obtained after injection has been completed and Fig.

17 that obtained after extraction of the upper 32 from the die 72, for example by performing a movement which is the reverse of the rotary/translatory movement performed during the phase of coupling, and after opening of the shells 38 and removal of the form 34.

The sole 79, in addition to forming the tread of the shoe, extends over part of the toe 40 of the upper 32 (overlapping area indicated by 53 in Fig. 16).

It is clear that the cavity 74a and the edges 38 cooperate to define the form of the tread, while the cavity 74b defines the extension and the form of the area 53 where the upper 32 and the sole 79 overlap. In this case also the process does not produces any marks or scoring on the tread sole. It is clear that in the two processes the relative movement for joining together and coupling the dies 46, 72 and the assembly formed by form 30 + upper 32 + closed shells 36, plus if necessary the injected midsole 62, may occur equally well by moving both or only one of them relative to the other one. The convenience will be determined by practical requirements relating to design of the moulding machine. However, manual operation during the various steps, as well as different division of the shoe mould into shells or parts which can be joined together, are also possible. For example, it is possible to divide the die 72 or 76 into two dies, one suitable for moulding an overlapping area on the toe and the other on the heel of the upper. Figures 20 and 21 show a possible embodiment of a part of a moulding machine according to the invention, in particular the mechanism which obtains the described relative movement of the upper 32 and the die 46 used in the first process. All this which has now been described is also applicable to the second process where the die 72 is employed The two shells 36 are arranged between two gripping surfaces 85 which grip them where required. The die 46 is arranged between the two shells 36 and is connected to a fixed upper cross-piece 87 by means of an actuating means mechanism 99 comprising a toggle 89 formed by two identical pairs of segments 90, 91 hinged with pins 93, and a pair of identical straight bars 94 hinged by means of other pins 93. The common hinge of the segments 90, 91 is connected to a piston 95 which is operated in a linear manner by an actuating system 96, while the mechanism 99 is hinged on the die 46 by means of a bracket 97.

The operating principle of the machine is as follows.

The cross-piece 87 is displaced towards the shells 36 in the direction Dl shown in Fig. 20 using known actuating means until the die 46 is arranged inside the said shells 36 (Fig. 20). The piston 95 is extended and tends to push the toggle 89. As a result, owing to the dimensions of the mechanism 99, the die 46 is inclined with respect to a horizontal plane, and its cavity 48b is not yet in contact with the upper 32, but instead faces its toe end 40 at a certain distance. The actuating system 96 is then operated so as to retract the piston 95

(direction D2 in Fig. 20). The action of the piston 95 causes the toggle 89 to extend, with the result that the die 46 is lowered and the bars 94 are pivoted towards the actuating system 96 (direction S in Fig. 20), with the further result that the die 46 also moves towards the shells 36. These two movements are combined in a rotary/translatory movement which has the effect of positioning the horizontal die 46 between the shells 36 and inserting the toe 40 into the cavity 48b. After introduction of the plastic material inside the mould cavity, a movement of the piston 95 and the cross-piece 87 which is the reverse of the previous allows removal of the die 46 from the upper 32, without any damage either to the latter or to the newly moulded part. From the above description it can be clearly understood how the invention eliminates the drawbacks which characterize the methods according to the state of the art and therefore the shoes thus produced.

Finally, it is understood that, within the scope of the following claims, the present patent also protects other embodiments of the method, the mould and the machine as well as the shoes which may be produced with them.

Claims

1. Method for the production, by means of injection/casting directly onto the upper (32), of a shoe formed at least by one sole part (50; 79) and an upper (32), where the former overlaps in an overlapping area (53) the toe (40) and/or the heel of the latter, and the upper (32) is enclosed inside a first mould (36) which grips it at the edges and which defines a first cavity (49; 81) where, after introduction of the material, the sole part is formed, characterized by the fart of:

- forming the first mould (36) so as to grip the upper (32) leaving at least one zone (39) of the toe (40) and/or the heel thereof exposed; - forming a second mould (46; 72) as a single-piece block comprising a second mould cavity (48, 74a, 74b) with which the sole part (50; 70) is formed in the overlapping area (53);

- coupling the first mould (36) to the second mould (46; 72) so as to form the first cavity (49; 81) and so as to introduce the exposed zone (39) of the upper (32) into the second cavity (48, 74a, 74b).

2. Method according to Claim 1, in which the first mould is formed with two separable moulds (36) in the form of a half-shell.

3. Method according to Claim 2, in which the separable moulds (36) are formed so as to leave the bottom of the upper (32) exposed when it is gripped between them.

4. Method according to any one of the preceding claims, in which the block (46; 72) of the second mould is formed so as to comprise a cavity (48a; 74a) which defines the shape of the sole part (50; 70) on the bottom of the upper (32).

5. Method according to Claim 4, in which the first cavity is in communication with the second cavity.

6. Method according to any one of the preceding claims, in which the first mould and the second mould are coupled together by means of a relative movement thereof.

7. Method according to Claim 6, in which the relative movement is a combination of a translatory movement and a rotation.

8. Method according to any one of the preceding claims, in which, before forming the sole part, the first mould is coupled to a third mould (55) and an intermediate piece of midsole (62) is formed on the bottom of the upper, the sole part being then formed so as to cover the intermediate piece of midsole (62).

9. Method according to Claim 8, in which said intermediate piece of midsole (62)is formed with dimensions so as to not be positioned over the entire joining surface area of sole and upper.

10. Method according to any one of the preceding claims, in which the sole part is formed as a single piece.

11. Mould (36) for the production of a shoe formed at least by one sole part (50; 70) and an upper (32) which can be operated so as to grip the edges of the upper and define a mould cavity (44) for forming the sole part following the introduction of material, characterized in that it is formed so as to grip the edges of the upper (32) leaving at least one zone (39) of the toe (40) and/or the heel thereof exposed

12. Mould (36) according to Claim 11, in which the mould comprises two separable moulds (36) in the form of a half-shell.

13. Mould according to Claims 11 or 12, in which the mould is formed so as to leave the bottom of the upper (32) exposed.

14. Mould (46; 72), for the production of a shoe formed at least by one sole part (50; 79) and an upper (32), which can be coupled to the mould (36) according to one of Claims 11 to 13 and cooperating therewith so as to form the mould cavity (49; 81) of the sole part (50; 79), characterized in that it comprises at least one additional mould cavity (48b; 74b) in which the sole part is formed at an overlapping area (53) where the sole part (50; 79) and the upper (32) overlap on the toe (40) and/or on the heel of the upper.

15. Mould (46; 72) according to Claim 14, in which the mould consists of a single-piece block.

16. Mould (46; 72) according to Claims 14 or 15, in which the at least one additional mould cavity is formed in a block (51, 76) projecting from a base block (47; 73) having, formed therein, another mould cavity (48a; 74a) which defines the shape of the sole part.

17. Machine for producing, by means of injection/casting directly onto the upper, a shoe formed at least by one sole part (50; 79) and an upper (32), where the former overlaps in an overlapping area (53) the toe (40) and/or the heel of the latter, comprising:

- a first mould (36) which can be gripped around the edges of the upper (32) and which defines a first cavity (49; 81) for forming the sole part (50; 79) following the introduction of material;

- a second mould (46; 72) which can be joined to the first mould (36) and cooperating therewith so as to form the first cavity; characterized in that it comprises actuating means (99) for joining the first mould to the second mould by means of a relative rotary/translatory movement.

18. Machine according to Claim 17, in which the first mould is formed according to Claims 11 to 13.

19. Machine according to Claims 17 or 18, in which the second mould is formed according to Claims 14 to 16.

20. Shoe formed according to the method of any one of Claims 1 to 10.

21. Shoe formed by means of the mould according to any one of Claims 11 to 16.

22. Shoe formed by means of the machine according to any one of Claims 17 to 19.