WO2019193288A1 - Extrusion facility for profile strips produced from elastomeric mixtures - Google Patents

Abstract

An extrusion facility (1) for producing a profile strip, such as a tread made from elastomeric mixtures by coextrusion, comprising several extruders (10, 20, 30, 40, 50, 60) for feeding elastomer mixture to an extrusion head comprising distribution channels for conveying the flow of elastomeric mixture originating from each extruder via a dedicated distribution channel to a die that defines the shape of a first co-extruded profile. According to the invention, the facility comprises at least one second extrusion head (2') capable of being connected to the extruders (10, 20, 30, 40, 50, 60) of the facility instead of the first and that is produced in such a way as to convey the flows of elastomeric mixtures originating from at least two extruders of the facility into a common distribution channel (5c) before reaching a die (3') that defines the shape of a second co-extruded profile.

Description

 EXTRUSION SYSTEM FOR PROFILE TAPES MADE OF ELASTOMERIC MIXTURES

The invention relates to the field of extrusion of elastomeric mixtures for the manufacture of tires. More particularly, it relates to the manufacture of coextruded complex profile strips based on elastomeric mixtures such as treads for tires.

In a known manner, a tire tread in the form of a complex section is produced by coextrusion of elastomeric mixtures, most of which have different compositions, by using several extruders connected to a common extrusion head. In known manner, an extruder is formed of a cylindrical body or fixed sleeve inside which is an Archimedean screw coaxial with the longitudinal axis of the sleeve and which is rotated around it. Its function is to homogenize a rubber mix introduced therein and to push it towards the outlet die of the extrusion head. For a complex product, the exit die receives several mixtures of elastomers of different compositions arranged side by side and which join before the exit. The die has an outlet orifice whose geometric shape determines the profile of the coextruded rubber band. This profile can be defined between a fixed profiled blade which cooperates with a rotating roller or with a fixed wall. To manufacture a tread by coextrusion, it is generally used an extruder by type of elastomeric mixture (by type it comprises composition thereof), the extruder dimensions (the diameter of the extruder screw ) being chosen proportionally to the volume of extruded mixture. For example, for a tread whose outer portion for rolling represents 80% of the volume and to which an underlayer is added for about 15% of the volume and two side edges together representing the remaining 5%, three extruders: a larger first with a screw diameter of 250mm, a second for the underlay having a screw diameter of 200mm and a third small extruder with a diameter of l20mm. [0004] At present, it is sought to improve the performance of tires via more complex bearing belts which comprise more components, for example up to seven different components, with very variable proportions of volume between the various components. Each component has its well-defined properties, for example the rolling part located outside the profiled strip comprises an elastomeric composition comprising silica with good rolling resistance properties, supported by an elastomeric band of different composition with different properties. damping, with a small strip of conductive elastomeric compound which is inserted into the two preceding ones, all supported by an undercoat with good adhesion properties with the components located radially inside the tire blank, as well as that side edges in a mixture different from the previous, or a mixture that incorporates mixed falls. Thus, each mixture having different properties from another, it is obviously necessary to increase the number of extruders to manufacture such a complex tread. [0005] FIG. 1 illustrates an exemplary extrusion installation of the state of the art in which an extruder is used for each product that composes the tread illustrated in FIG. 2. The longitudinal axes of the extruders which consist are in different planes and converge to a common extrusion head. The large size of such an installation with seven extruders arranged one above the other is observed.

Such a complex installation represents a significant investment in the manufacture of tires and, therefore, it is interesting to use all the potential it has. In other words, it is sought to produce with the same installation a complex coextruded tread, for example seven components, but also a less complex coextruded tread, comprising for example three components.

DE 102012111439 describes an extrusion plant which uses five adjacent extruders located on the same side of a common extrusion head and in which two of the five extruders are arranged in a box. same plan and collaborate to achieve the same product. Such an arrangement certainly makes it possible to optimize the space available on one side of the extrusion head. However, this device does not provide enough flexibility to be able to adapt to the change in coextruded product structure and which or wants to easily change the number of components.

An object of the invention is to overcome the drawbacks mentioned here and to propose an optimized construction extrusion installation and very flexible in use, which can easily go from the extrusion of a complex product to extrusion a simpler product, using all the extruders that make it up. This object is achieved by the invention which proposes an extrusion plant for manufacturing a strip of profile, such as a tread, based on elastomeric mixtures by coextrusion, said installation comprising a first extrusion head as well as a plurality of elastomer mixing feed extruders of said first extrusion head, the first extrusion head having distribution channels for channeling the elastomeric mixture stream from each extruder via a dedicated distribution channel to a die which defines the shape of a first coextruded profile, so that the various elastomeric mixtures extruded by the extruders do not meet before reaching said die, the installation being characterized in that it comprises at least one second extrusion head adapted to be connected to the extruders of the installation to the position of the first extrusion head and which is designed to channel the flows of elastomeric mixtures from at least two extruders of the installation into a common distribution channel before reaching a die which defines the shape a second coextruded profile.

In other words, the installation of the invention comprises on the one hand a number of extruders chosen so as to achieve a complex product whose number of components is equal to the number of extruders of the installation and using a first extrusion head, and on the other hand, a second extrusion head made to cooperate at least two extruders when it is put in place in place of the first. This makes it possible to be able to produce at the same time profiled strips coextruded tread type for pneumatic very complex, but also more simple products with the same installation.

Preferably, the common distribution channel is a channel which extends in a direction substantially perpendicular to the flow direction of the flows of the elastomeric mixtures from said at least two extruders. Such a solution makes it possible to have a better cohesion of the two mixtures and to avoid any problem of interface between the two.

Advantageously, the extruders are arranged on either side of the head relative to a plane of symmetry passing through the outlet orifice of the die. This solution allows a better balance of flows from different extruders.

In a variant of the invention, two longitudinal streams from two extruders meet in a longitudinal collector channel which opens into the common distribution channel.

In another variant of the invention, two longitudinal flows from two extruders meet in a transverse collector channel which opens into the common distribution channel.

In yet another variant, three longitudinal streams from three extruders meet via a longitudinal collector channel and a transverse collector channel in a common distribution channel. Preferably, the extrusion head, in this case the first extrusion head, respectively the second extrusion head, is connected directly to the extruders without there being a mixture transfer channel. elastomer between the two. More preferably, each of said first extrusion head and second extrusion head is arranged so as to be able, when it comes in turn, to be directly connected to the extruders without there being an elastomer mixing transfer channel between said extruders and the extrusion head considered. Thus, the end of the screw of each extruder arrives substantially at the corresponding inlet orifice in the extrusion head, which greatly reduces the pressure drop. We can use the volume remaining to accommodate wider extruder head inlet channels than prior art extruders, thereby reducing mixture heating and increasing machine productivity.

Advantageously, said common distribution channel is located in the second extrusion head opposite the outlet of the die. Thus, the flows coming from different extruders are converged in a common distribution channel at the earliest, well before the exit of the die, which makes it possible to have a better cohesion of the mixtures.

[0018] Preferably, the extruders are identical. This facilitates the maintenance of the installation. Advantageously, the extrusion head, whether the first extrusion head and / or the second extrusion head, comprises a set of several removable plates arranged side by side. Such a removable plate construction makes it possible to obtain an extrusion head of simplified and flexible construction.

The object of the invention is also achieved with a method of manufacturing profile strip, such as a tread, based on several mixtures of elastomers of different composition by coextrusion with the aid of several extruders. supply of elastomeric mixtures of an interchangeable extrusion head, characterized in that: a first extrusion head adapted to the profile to be coextruded is chosen and introduced into a support provided for this purpose in the installation by connecting it the extruders of the installation in order to channel the flow of elastomeric mixture from each extruder via a dedicated distribution channel to the die; it is locked in place by means of quick fastening means; the profile strip is coextruded; the first extrusion head is removed and replaced with another extrusion head, forming a second extrusion head, adapted to the new profile and able to channel the flow of elastomeric mixtures from at least two extruders from the facility into a common distribution channel before reaching the die.

The invention will be better understood from the following description, which is based on the following figures: - Figure 1 is a schematic perspective view of an extrusion plant according to the state of the art ; Figure 2 is a perspective view of a first tread example; Figure 3 is a perspective view of a second tread example; FIG. 4 is a perspective view of the extrusion plant of the invention; Figure 5 is a schematic longitudinal sectional view of the installation of Figure 4; Figure 6 is a schematic longitudinal sectional view of the extrusion installation according to a first embodiment of the invention; - Figure 7 is a schematic longitudinal sectional view of the extrusion plant according to a second embodiment of the invention. FIG. 8 is a diagrammatic view in longitudinal section of the extrusion installation according to a third exemplary embodiment.

In the different figures, identical or similar elements bear the same reference. Their description is not systematically repeated.

FIG. 1 illustrates an extrusion installation according to the state of the art which uses several extruders A, B, C, D, E, F and G which converge together in a common extrusion head T to produce a complex profiled product by coextrusion which forms a tire tread 100 '. The tread 100 'is better visible in FIG. 2 in which we have identified the various components which constitute by the letter which corresponds to the extruder from which the component arrives. Thus, the underlayer arrives from the extruder A, the adjacent layer above it from the extruder B and the outer layer from the extruder C. Two extruder profiles E and F complete the outer layer which also comprises two conductive inserts from the extruder D. The assembly is finally completed by two side edges from the extruder G.

The extrusion installation of the invention has different embodiments. It is capable of producing a complex profiled product of the type illustrated in FIG. 2, but also a simpler profile product of the type illustrated in FIG.

Figure 4 illustrates an extrusion installation 1 of the invention comprising several extruders 10, 20, 30, 40, 50, 60 to produce a profile product by coextrusion in a common extrusion head 2. The shaped product obtained is a tread 100 and comprises several components, in the example illustrated in number of six, made of elastomeric materials from different extruders. The extruders 10, 20, 30, 40, 50, 60 have been schematically illustrated by only showing their respective screws, but it is understood that, generally known, the screw of each extruder rotates inside a sheath cylindrical having a supply inlet of a mixture of elastomers and an outlet which opens into the extrusion head 2. The screw of each extruder is rotated about its longitudinal axis by a motor, located at the end of the screw opposite to that which arrives in the extrusion head, so that it rotates inside its respective sleeve to provide the extrusion head with a homogenized elastomeric mixture and ready to be shaped by it. The extruders 10, 20, 30, 40, 50, 60 are arranged on either side of the extrusion head 2 and the longitudinal axes of the screws are located in the plane of symmetry P of the tread 100. The plane of symmetry P is a vertical plane which passes through the center of gravity of the strip when it is a symmetrical product or, for an asymmetric product, by the center of inertia of this one. Extruders located on both sides of the extrusion head includes extruders which face each other by being arranged on both sides with respect to a vertical plane perpendicular to the plane of symmetry P and which passes through the center of the extrusion head 2. such an arrangement makes it possible to balance the flows of the various extruders which pass through the extrusion head. In operation, when each extruder is fed with an elastomeric mixture, the various mixtures extruded by the extruders 10, 20, 30, 40, 50 and 60 pass through the distribution channels provided for this purpose in the head of the extruder. extrusion 2, here a first extrusion head 2, without mixing and converge to a die 3 which gives the final shape of the product, in this case to the tread 100. Thus, each elastomeric mixture derived from one of said extruders 10, 20,

30, 40, 50 and 60 passes through the first extrusion head 2 via a distribution channel which is exclusively dedicated to it, and which allows, for each elastomeric mixture from one of the extruders of the installation 1, to conveying said elastomeric mixture to the die 3 separately from the other elastomeric mixtures from the other extruders, such that said elastomeric mixture can not come into contact with any of the other elastomeric mixtures, from other extruders and conveyed by the other dedicated distribution channels, before reaching the sector 3.

Such elastomeric mixtures are, for example, elastomer or rubber-based mixtures used to create a tread assembly such as: a first 100% natural rubber material for producing a sub-compound. layer, then a second material for producing the outer portion of the tread made of 100% synthetic rubber comprising for example silica, and a third material without silica but having absorbing properties, followed by a fourth and fifth material for making the side edges composed for example of a mixture of natural rubber / synthetic rubber (20% to 80% natural rubber), and a sixth material which is a conductive mixture comprising a mixture of natural rubber / synthetic rubber and carbon black. As illustrated in Figures 4 to 8, the extruders 10, 20, 30, 40, 50, 60 are arranged with their longitudinal axes 11, 21, 31, 41, 51, 61 parallel to each other and perpendicular to the walls. 22 and 23 of the extrusion head 2, 2 ', 2 ", 2"' three extruders 10, 30 and 50 being located on the right with respect to the median vertical plane of the extrusion head and the other three 20, 40 and 60 to the left of this plane. Extruders on the right and those on the left face each other, they are located in pairs at the same height, their longitudinal axes being located in the same plane. However, the extruders on the right can be arranged at a height different from those on the left. In a variant, the longitudinal axes of the extruders are not parallel, they form an angle between them, the angle formed by the longitudinal axes of two adjacent extruders may be different from that formed by the longitudinal axes of two other adjacent extruders. In yet another variant, it is possible to envisage a different number of extruders on the right compared to those situated to the left of the head.

The extrusion head 2 is constituted by a stack of several plates, in number of seven in the example shown in Figure 5: 2a, 2b, 2c, 2d, 2e, 2f, 2g parallel and parallel with each other at the side walls 22, 23 of the extrusion head and perpendicular to the longitudinal axes of the extruders 10, 20, 30, 40, 50, 60. The plates 2a to 2g have a length equal to or slightly shorter than that of the side walls 22, 23 of the head and define between them transverse distribution channels 5a, 5b, 5c, 5d, 5f, 5g which convey the elastomeric mixture from the extruder of the installation to the exit die 3. The plates 2a to 2g are removable and are held together and attached to the side walls of the extrusion head for example by a screw fastener (not shown). The installation of FIG. 2 is suitable for producing the six-component tread 100 of FIG. 4. According to the invention, the installation comprises a second removable extrusion head making it possible to channel the flow of mixtures. elastomers from at least two extruders of the plant in a common distribution channel before reaching the exit die. In a first embodiment and as best seen in Figure 6, the second extrusion head 2 'is made so that two extruders 50 and 60 facing each other flow in a longitudinal collector channel 6 in being connected with their outlets of their respective sheath to the inlet orifices 52, respectively 62 in the second extrusion head 2 '. Each extruder 50, 60 sends in the second extrusion head 2 'a flow of material F50, respectively F60, which enters the head in the direction of the longitudinal axis of the extruder F and the two flows F50 and F60 meet in the collector channel 6 and then suddenly change direction, substantially perpendicular to the longitudinal axes of the extruders 50, 60, following the common transverse distribution channel 5c towards the die 3 '. In the example of FIG. 6, the two longitudinal flows F50 and F60 come together and form a common transverse flux, the resulting material flux Fc obtained by the combination of the first two. By extruders facing each other, it will be understood that the extruders 50 and 60 are each mounted in an inlet orifice 52, respectively 62 of the second extrusion head 2 ', the inlet orifices 52 and 62 being located opposite each other. opposite in the extrusion head 2 'or on both sides of the median plane thereof.

In a second exemplary embodiment of the invention illustrated in FIG. 7, the second extrusion head 2 "is made in such a way that two superposed extruders 40 and 60 flow in a transverse collector channel 7 which communicates directly with the common transverse distribution channel 5d in which the flow of mixtures meet and travel together the distribution channel before reaching the die 3 ". More particularly, each extruder 40, 60 sends into the second extrusion head 2 "a material flow F40, respectively F60, which enters the head in the direction of the longitudinal axis of the extruder. The longitudinal flows F40 and F60 abruptly change their direction in contact with the plate 2d, substantially perpendicularly to the longitudinal axes of the extruders 40, 60. The two flows meet at the level of the inlet orifice 42 and follow the distribution channel 5 In the example of FIG. 7, the two longitudinal flows F40 and F60 come together and form a common transverse flow, the resulting material flow Fc obtained by the combination of the first two. By extruders superimposed, it is understood that the extruders 40 and 60 (it understands their longitudinal axes) are arranged in horizontal planes or inclined but located at a distance vertically from one another. Thus, the inlet orifices 42, 62 respectively of the second extrusion head 2 ", are located vertically and on the same side in the extrusion head 2" as seen with respect to the median plane thereof. .

In a third embodiment of the invention illustrated in Figure 8, the second extrusion head 2 "'is made so that two extruders 50 and 60 facing each other flow into a longitudinal collector channel 6 and two superimposed extruders 40, 60 flow into a longitudinal collector channel 7, so that the resultant stream of three extruders form a common stream that flows directly into the common transverse distribution channel 5c. The flow thus obtained travels through the distribution channel 5c before reaching the die 3 "'. More particularly, each extruder 50, 60 sends in the second extrusion head 2 "a flow of material F50, respectively F60, which enters the head in the direction of the longitudinal axis of the extruder and the two flows F50 and F60 meet in the longitudinal collector channel 6 then change abruptly direction together, substantially perpendicularly, following the common transverse distribution channel 5c towards the die 3 "'. The longitudinal flow of the extruder 40 and a portion of that leaving the extruder 60 change direction substantially perpendicular to the longitudinal axis of the extruder at the outlet thereof and join the flow of materials from longitudinal collector channel, which converges three longitudinal flows in a common transverse channel 7. The common flow Fc obtained by the combination of the three flows F50, F60 and F40 travels the distribution channel 5c to arrive in the die 3 " .

Thus, when feeding two extruders 50 and 60 facing each other or two extruders 40, 60 superimposed or any combination of extruders facing each other and superimposed with the same material (it comprises an elastomeric mixture of identical composition) it is possible to obtain a simpler coextruded product because it has fewer components, with the same facility that can produce a more complex coextruded product. When two of the six extruders the installation of Figure 4, we achieve a tread 200 three-component a, b, c, as shown in Figure 3.

According to an advantageous aspect of the invention, the extrusion head is interchangeable and is directly connected to the extruders 10, 20, 30, 40, 50, 60 without there being a mixture transfer channel. elastomer between the two. Thus, the choice of having two extruders work together is done by arranging the appropriate extrusion head and then driving the extruders according to the geometry of the product that is to be obtained. The amount of product sent to the die is adjusted by acting on the rotational speed of the screws of the extruders. In addition, the extruders 10, 20, 30, 40, 50, 60 flow directly into the extrusion head 2, namely in the first extrusion head or, respectively, in the second extrusion head when the latter is substituted for the first extrusion head, which significantly reduces the pressure drops.

According to an advantageous aspect of the invention, it is converged as soon as possible, in the lower part or opposite to that of output via the die 3 ', 3 "of the extrusion head, the mixture flows F50 and F60, respectively F40 and F60, that we want to collaborate. This has the advantage of good cohesion of the two mixtures which form a single component, without problem of decohesion at the interface of the two materials.

According to another advantageous aspect of the invention, the extruders 10, 20, 30, 40, 50, 60 of the installation 1 are identical. For example, they have extrusion screws with a diameter of 100mm. This makes it possible to make them collaborate very easily in adequacy with the need of the product to be manufactured. This facilitates the maintenance of the installation.

Furthermore, an arrangement vis-à-vis is advantageous because it decreases the size of the dimensional tooling, including the extrusion head, which ensures better ergonomics and at the same time reduces weight of it. In one variant of the invention, all the extruders 10, 20, 30, 40, 50, 60 of the installation 1 are Archimedean screw extruders. In another variant of the invention, at least two of the extruders of the installation 1 are extruders volumetric, for example of the type volumetric extruders bi-screw counter-rotating interpenetrating nets and conjugate profiles.

In operation, one chooses a first extrusion head 2 capable of producing a complex tread 100, based on several elastomer mixtures of different composition by coextrusion of elastomeric mixtures from the extruders 10, 20, 30 , 40, 50, 60 and introduced into a support provided for this purpose in the installation 1. The first extrusion head is locked in place by means of quick fastening means (not shown in the figures) . The extrusion operation is carried out. When one wants to change the type (structure, composition) of tread, one chooses a second extrusion head 2 ', 2 "adapted to the new tread 200 based on several mixtures of elastomers of different composition by coextrusion of elastomeric mixtures from the extruders 10, 20, 30, 40, 50, 60 and introduced into a support provided for this purpose in the installation 1, and then locked in place said second extrusion head to using quick fasteners. The new tread 200 has fewer components than the first, but is fed by the same extruders some of which send the same mixture in a common distribution channel inside the extrusion head before reaching the die. exit.

Other variants and embodiments of the invention may be envisaged without departing from the scope of its claims.

Thus, it is possible to arrange more than six extruders on either side of the extrusion head, or even on the other faces of the extrusion head which are not dedicated to one another at the outlet of the blends. in the direction of the extrusion die and the other to the gripping of the head to move at least two of them working with different mixtures and some others with the same mixture of elastomers.

Advantageously, and regardless of the number of extruders concerned of the installation 1, the invention makes it possible to use the same set of several extruders 10, 20, 30, 40, 50, 60 to alternately perform a first one. profiled, complex, or on the contrary a second section, simpler than said complex section, according to which one uses, in association and in cooperation with this same set of several extruders: - Or the first extrusion head 2, intended to form the first section, complex, and which defines for each extruder of the set of several extruders a dedicated route for the elastomeric mixture concerned, from said extruder to the die 3, transport path which is materialized by the corresponding dedicated distribution channel and which is isolated from the other routes used by the streams of elastomeric mixtures from the other extruders of the same set of several extruders, so as to separate the flow of elastomeric mixtures from one another to the die 3 where said streams converge to form the first section;

- Or the second extrusion head 2 ', 2 ", 2"', intended to form the second section, simpler, and in which, unlike the first extrusion head, at least two channels respectively from at least two extruders of this same set of several extruders converge in a zone of confluence which is located within said second extrusion head remote from the die 3 ', 3 ", 3"', upstream of said die in the direction of flow, so that the at least two streams of corresponding elastomeric mixtures meet before reaching said die, and then jointly borrow, from their confluence zone to said die, the same shared channel, which is materialized by the corresponding common distribution channel, which distribution channel is thus common to said two extruders.

Claims

1. Installation (1) for extrusion to manufacture a profile strip, such as a tread (100, 200) based on elastomeric mixtures by coextrusion, said installation (1) comprising a first extrusion head (2) and several extruders (10, 20, 30, 40, 50, 60) for supplying elastomer mixtures with said first extrusion head (2), the first extrusion head (2) having distribution channels permitting channeling the flow of elastomeric mixture from each extruder via a dedicated distribution channel to a die (3) which defines the shape of a first coextruded profile, so that the different elastomeric mixtures extruded by the extruders not reach before reaching said die (3), the installation (1) being characterized in that it comprises at least a second extrusion head (2 ', 2 ", 2"') capable of being connected to the extrudeu it (10, 20, 30, 40, 50, 60) of the installation in place of the first extrusion head (2) and which is made to channel the flows of elastomeric mixtures from at least two extruders of the installation in a common distribution channel (5c, 5d) before reaching a die (3 ', 3 ", 3"') which defines the shape of a second coextruded profile. 2. Installation (1) according to the preceding claim, characterized in that the common distribution channel is a channel which extends in a direction substantially perpendicular to the flow direction of the flow of the elastomeric mixtures from said at least two extruders . 3. Installation according to one of claims 1 or 2, characterized in that the extruders (10, 20, 30, 40, 50, 60) are arranged on either side of the head relative to a plane of symmetry. (P) passing through the exit orifice of the die. 4. Installation according to one of claims 1 to 3, characterized in that two longitudinal flows from two extruders (50, 60) meet in a longitudinal collector channel (6) which opens into the common distribution channel (5). vs). 5. Installation according to one of claims 1 to 3, characterized in that two longitudinal flows from two extruders (40, 60) meet in a transverse collector channel (7) which opens into the common distribution channel (5d ). 6. Installation according to one of claims 1 to 3, characterized in that three longitudinal flows from three extruders (40, 50, 60) meet via a longitudinal collector channel (6) and a transverse collector channel (7). in a common distribution channel (5c). 7. Installation according to one of the preceding claims, characterized in that the first extrusion head (2), respectively the second extrusion head (2 ', 2 "), is connected directly to the extruders (10, 20, 30, 40, 50, 60) without there being an elastomer mixing transfer channel therebetween. 8. Installation according to one of the preceding claims, characterized in that said common distribution channel is located in the second extrusion head (2 ', 2 ", 2"') opposite the exit of the die (3 ', 3 ", 3"'). 9. Installation according to one of the preceding claims, characterized in that the extruders (10, 20, 30, 40, 50, 60) are identical. 10. Installation according to one of the preceding claims, characterized in that the first extrusion head (2), and / or respectively the second extrusion head (2 ', 2 ", 2"') comprises a set several removable plates arranged side by side. 11. A method of manufacturing profiled strip, such as a tread (100, 200), based on several mixtures of elastomers of different composition by coextrusion with the aid of several extruders (10, 20, 30, 40, 50, 60) for supplying elastomeric mixtures of an interchangeable extrusion head (2, 2 ', 2 ", 2"'), characterized in that: a first extrusion head (2) adapted to the profile to be coextruded and introduced into a support provided for this purpose in the installation by connecting it to extruders of the plant for channeling the flow of elastomeric mixture from each extruder via a dedicated distribution channel to the die (3); it is locked in place by means of quick fastening means; the profile strip is coextruded; the first extrusion head (2) is removed and replaced with another extrusion head forming a second extrusion head (2 ', 2 ", 2"') adapted to the new profile and capable of channeling the flow of elastomeric mixtures from at least two extruders of the plant into a common distribution channel (5c, 5d) before reaching the die (3 ', 3 ", 3"').