WO2018055650A1

WO2018055650A1 - Carousel-type machine for making injection molded pieces comprising two materials and related production method

Info

Publication number: WO2018055650A1
Application number: PCT/IT2017/000184
Authority: WO
Inventors: Alfonso MOTTO
Original assignee: Wintech S.R.L.
Priority date: 2016-09-01
Filing date: 2017-08-30
Publication date: 2018-03-29
Also published as: IT201600088724A1

Abstract

A method is described for making injection molded pieces comprising two different materials for producing soles (10) for footwear with tread and midsole, wherein the first and second material are injected in a same mold (6) comprising a first imprint (6a) and a second imprint (6b) which, by being inserted in succession in a matrix (6c), locate recesses wherein tread and midsole are injected, the production being performed on machines of a carousel type (2), the carousel (2) comprising three stations (2a, 2b, 2c); the production of the soles (10) is performed in three revolutions of the carousel (2) according to the following modes: at the first revolution, the tread is extracted in the first station (2a); at the second revolution, the midsole is injected in the first station (2a); at the third revolution, the complete sole (10) is injected in the third station (2c) and the tread of the following sole (10) is injected; in order to produce a complete sole (10) every two revolutions of the carousel (2).

Description

CAROUSEL-TYPE MACHINE FOR MAKING INJECTION MOLDED PIECES

COMPRISING TWO MATERIALS AND RELATED PRODUCTION METHOD

The present invention refers to a machine, of the carousel type, for making injection molded pieces comprising two different materials, in particular for producing soles for footwear, and to a particular production method, suitable to allow cooling the molded piece, before its extraction from the mold.

Shoe soles, above all in sports shoes, are often made with two plastic materials having different mechanical features. The tread is made with a first material, more resistant to wear, while the midsole is made with a second, elastically yielding, material, the midsole being the layer which is placed between tread and upper. Often, above all for sports shoes, the two materials are also of different colors, to obtain particular chromatic effects, according to the known art .

To obtain a perfect adhesion between the two layers, it is necessary that the injection of the second layer occurs when the first layer is not yet completely cooled. Moreover, to avoid distortions of the finished product, it is necessary that this latter one is extracted from the mold when its solidification is complete enough.

According to the prior art a rotary mold is used with two imprints and a matrix. When the mold is in a first position, wherein the first imprint is inserted in the matrix, a recess is obtained, within which the material for making the tread is injected. Afterwards, the mold is opened and is rotated to insert the second imprint into the same matrix, wherein the newly injected tread is present. In this second position, a second recess is obtained, above the tread, wherein the material for making the midsole is injected.

This production method is performed both with dynamic machines, of the carousel type, and with static machines. In both cases, the production method is determined by its cooling times: due to this, the carousel machines with a high number of stations obtain a greater production with respect to static machines. However, these machines are scarcely flexible, costly, cumbersome, of a difficult handling and not suitable for limited productions. In fact, they are capable of producing with competitive costs only if used with their maximum potentialities, thing that is not often possible, especially during periods of crisis.

In order to solve the described inconvenience, often small-sized static machines are used, which however particularly suffer from the cooling problem, since they are forces to remain inactive for all the necessary time to obtain enough solidification, with severe prejudice for their productivity.

The above inconveniences are solved at least in part by the present invention, which proposes a method, and a machine for performing such method, respectively according to claims 1 and 4, for making injection molded pieces comprising two different materials, in particular for producing soles for footwear comprising a tread and a midsole .

Such method performs the production on machines of the carousel type, where said first and second material are injected in the same, suitably configured mold, wherein the production of soles is performed in three revolutions of the carousel, according to the following modes :

• at the first revolution, the tread is injected;

· at the second revolution, the midsole is injected;

• at the third revolution, the tread of the following sole is injected, and after this the complete sole is extracted;

so that, every two revolutions of the carousel, a complete sole is produced. Another important feature of the method of the invention is that the sole is kept in the mold for two revolutions after injecting the midsole, in order da complete the solidification, and that, in part of the path, the mold is open.

The machine for producing these soles for footwear, comprising a tread and a midsole, is of the type equipped with:

• a carousel having a plurality of stations, in each of which there is a mold;

• a first injector to inject^' a first material for making the tread;

• a second injector to inject a second material for making the midsole;

said carousel being programmed to take in a sequence the mold next to :

• the first injector for injecting the tread;

• the second injector for injecting the midsole;

• means for extracting the complete sole from said mold;

said mold being of the type comprising a first and a second imprint which, by being inserted in succession into a matrix, locate recesses wherein the sole tread and midsole must be injected, and the carousel comprises three stations wherein: • the first and second injector are next to the first station;

• the means for extracting the complete sole from the mold are next to the third station;

the machine being programmed to perform the production of the soles in compliance with the previously described method.

The use of the machine and of the method in compliance with the invention allows removing the inactive steps, though keeping the advantages of a small - sized machine, such as reduced costs and overall sizes and easy production management, and allows obtaining a quick production method comparable with a carousel with a number of stations which is three times bigger.

The invention will now be described, as a non- limiting example, according to a preferred embodiment thereof and with reference to the enclosed drawings, in which :

• figure 1 is a perspective view of a machine of the invention;

• figure 2 shows a diagram of the machine of the invention;

• figures 3, 4, 5 and 6 show the sequence of movements performed by the mold to be configured depending on the molding to be performed; • figures 7, 8 and 9 shows a production method of the invention.

Fig. 1 shows a machine (1) for molding two-color soles, suitable to perform the production method of the invention.

According to a preferred embodiment, this machine (1) comprises a carousel (2) with three stations (2a, 2b, 2c) , each one of which is occupied by a mold base (3) for molding the soles .

In the first station (2a) there is an injecting apparatus (4), comprising a pair of injectors (4a, 4b) and a press (5) , for example of the type which comprises a portal (5a) and an hydraulic cylinder (5b) .

The carousel (2) is rotatable with respect to a vertical axis and the mold base (3) pass, in a sequence, from the first station (2a) , to the second station (2b) and, finally to the third station (2c) , to then repeat the same movements.

Fig. 2 schematically shows the injecting apparatus (4) , arranged next to the first station (2a) . The injecting apparatus (4) comprises the pair of injectors (4a, 4b), schematically shown through two arrows. A first injector (4a) has the function of injecting the material composing the external part of the sole, namely the tread, while a second injector (4b) has the function of injecting the material composing the midsole.

The rotation of the carousel (2) , along the direction shown by the arrow, takes each mold base (3) to occupy in a sequence the first station (2a) , then the second station (2b) and then the third station (2c) , in each of which a working step occurs, as described below. In the third station (2c) there is an operator for extracting the soles from the mold.

Figures 3, 4, 5 and 6 show the mold base (3), on which a mold (6) is assembled for molding the soles. According to a preferred embodiment, the mold base (3) comprises a fixed base (3a) and a mobile element (3b) having the shape of a parallelepiped, assembled on a pair of actuators (7) , in order to be able to rotate around an axis "x" , which, when the mold base (3) is in the first station (2a) , is horizontal and laying on a plane perpendicular to the axis of the injectors (4a, 4b) .

The mold (6) comprises a first imprint (6a) and a second imprint (6b) , assembled on two contiguous faces of the parallelepiped (3b) , while a matrix (6c) remains fixed on the base (3a) of said mold base (3) , the matrix (6c) , in a sequence, being applied to the first and second imprint (6a, 6b) , according to the modes described below.

In practice: • when the first imprint (6a) of the mold (6) is inserted into the matrix (6c) , a first recess is obtained, in which the material for making the tread is injected, by the first injector (4a) (Fig. 3) ;

• when the second imprint (6b) of the mold (6) is inserted into the matrix (6c) , wherein there is an already formed tread, a second recess is obtained, in which the material for making the midsole is injected, by the second injector (4b) (Fig. 6) .

The passage from the configuration of Fig. 3 to the one of Fig. 6 occurs through the step of opening the mold (6) (Fig. 4) and the following rotation, along the direction of the arrow, of the mobile element (3b) (Fig. 5) .

The opening of the mold (6) , and its following closure, are performed through the action of the actuators (7) . Moreover, when the mold base (3) is in the first station (2a) , it is subjected to the action of the hydraulic cylinder (5b), shown in Fig. 1, which keeps the mold (6) closed during the injection.

The method of the invention is always performed during three revolutions of the carousel (2) . After having started the cycle, only two revolutions will then be necessary to extract a pair of finished soles.

Figures 7, 8 and 9 show the operations respectively performed in the first, in the second and in the third revolution of the carousel (2) .

Fig. 7a: Revolution 1, first station (2a)

The first imprint (6a) of the mold (6) is inserted into the matrix (6c), like in Fig. 3: the first injector (4a) injects the material for forming the tread of a first sole.

Fig. 7b: Revolution 1, second station (2b)

The mold remains closed and the cooling of the tread starts.

Fig. 7c: Revolution 1, third station (2c)

The mold (6) is opened, the mold base (3) rotates and takes the second imprint (6b) inside the matrix (6c) , being arranged for injecting the midsole, like in Figures 4 and 5.

Fig. 8a: Revolution 2, first station (2a)

The second injector (4b) injects the material composing the midsole. '

Fig. 8b: Revolution 2, second station (2b)

The mold remains closed and the cooling of the first complete sole starts.

Fig. 8c : Revolution 2, third station (2c)

The mold (6) is opened, the mold base (3) rotates and takes the first imprint (6a) inside the matrix (6c) , being arranged for injecting the tread of a second sole, while the first complete sole remains on the second imprint (6b), where the cooling continues.

Fig. 9a: Revolution 3, first station (2a)

The first injector (4a) injects the material for forming the tread of the second sole, while the first previous complete sole remains on the second imprint (6b), where the cooling continues.

Fig. 9b: Revolution 3, second station (2b)

The mold remains closed and the cooling of the tread of the second sole starts, while the previous complete sole remains on the second imprint (6b) , where it completes its cooling.

Fig. 9c: Revolution 3, third station (2c)

The first sole (10) , having completed its cooling, is extracted from the second imprint (6b) , then the mold (6) opens, the mold base (3) rotates and takes the imprint (6b) inside the matrix (6c) for the following injection of the midsole of the second sole, by the second injector (4b) , in the first station (2a) .

The method has been described on three revolutions, however, after the first three revolutions of the carousel (2) , the complete cycle for manufacturing a sole (10) is reduced to two revolutions, since the injection of the tread, which in the described method occurred at the first revolution of the carousel (2) , at steady state does not occur any more at the first revolution of the cycle, but at the second revolution of the previous cycle .

In other words, it can be stated that the manufacturing of a sole is performed in three revolutions, since at the first revolution the tread is injected, at the second revolution the midsole is injected, and at the third revolution the complete sole (10) is extracted. However, since at the third revolution, while the sole (10) is cooled, the tread of the following sole is injected, actually every two revolutions of the carousel (2) a complete sole (10) is manufactured .

As can be seen, every step of the method is active, so that the machine productivity is rather high and is about 30% higher than that of static machines, wherein it is necessary to wait, with an inactive machine, for the necessary time for cooling the molded piece.

From the previous description, the inventive concept on which the machine (1) of the invention is based, clearly stands out. The problem of obtaining the cooling of a molded piece is not present on big-sized carousel- type machines because, when the molded piece has reached the un-forming station, it is then cooled enough, due to the fact that the time for moving among the various stations is any way high with respect to the time necessary for its solidification.

In the machine (1) of the invention, wherein the carousel (2) comprises only three stations (2a, 2b, 2c) , the sole (10) is made remain in the machine (1) for two complete revolutions before its extraction from the mold (6) , thereby obtaining the same solidification, as in big-sized machines. The only difference is that the cooling of the complete sole (10) occurs in a closed mold only in the second station (2b) and immediately after the injection of the midsole, by the second injector (4b) . In fact, in the following third station (2c) , the mold (6) is opened and the sole (10) completes its solidification with open mold, namely on the second imprint (6b), on which it remains for a second revolution, till it goes back again to the third station (2c) , where it is extracted by the operator. The fact that the cooling of the complete sole (10) occurs with an open mold does not affect the product quality, since the adhesion to the second imprint (6b) is anyway enough to keep shape and sizes of the sole (10) stable.

The invention has been described, as a non-limiting example, according to a preferred embodiment. The skilled person in the art can devise several other embodiments, all falling within the scope of the enclosed claims.

Claims

1. Method for making injection molded pieces comprising two different materials, for producing soles (10) for footwear, comprising a tread and a midsole, wherein said first and second material are injected in a same, suitably configured mold (6) comprising a first imprint (6a) and a second imprint (6b) which, by being inserted in succession into a matrix (6c) , locate recesses wherein said tread and midsole of the sole (10) are injected, said production being performed on machines of a carousel (2) type, said carousel (2) comprising three stations (2a, 2b, 2c) , characterized in that the production of said soles (10) is performed in three revolutions of said carousel (2) according to the following modes:

• at a first revolution, the tread is injected in the first station (2a) ;

• at a second revolution, the midsole is injected in the first station (2a) ;

· at a third revolution, the complete sole (10) is extracted in the third station (2c) and the tread of the following sole (10) is injected;

so that, every two revolutions of the carousel (2) , a complete sole (10) is produced.

2. Method according to claim 1, characterized in that said sole (10) is kept in the mold (6) for two revolutions after injecting the midsole, in order to complete its solidification, without making said machine (1) inactive.

3. Method according to claim 1 or 2 , characterized in that, when said sole (10) remains in the mold (6) to complete its solidification, said mold (6) is open at least in a part of its path.

4. Machine (1) for making injection molded pieces comprising two different materials, for producing soles (10) for footwear comprising a tread and midsole, said machine (1) being equipped with:

• a carousel (2) having a plurality of stations, in each one of which there is a mold (6) ;

· a first injector (4a) , to inject a first material for making the tread;

• a second injector (4b) , to inject a second material for making the midsole;

said carousel (2) being programmed to take in a sequence the mold (6) next to:

• said first injector (4a) , for injecting of the tread;

• said second injector (4b) , for injecting the midsole;

· means for extracting from said mold (6) the complete sole (10) ;

said mold (6) being of the type comprising a first imprint (6a) and a second imprint (6b) which, by being inserted in succession into a matrix (6c) , locate recesses wherein said tread and midsole of the sole (10) are injected, characterized in that said carousel (2) comprises three stations (2a, 2b, 2c) wherein:

• said first and second injector (4a, 4b) are next to said first station (2a) ;

· said means for extracting the complete sole (10) from said mold (6) are next to said third station (2c) ;

said machine (1) being programmed to perform the production of said soles (10) according to the method of claims 1 to 3.