WO2004069522A1

WO2004069522A1 - Integrated plant for the production of articles made of reinforced polyurethane, relative method and polyurethane articles thus obtained

Info

Publication number: WO2004069522A1
Application number: PCT/IB2003/004787
Authority: WO
Inventors: Mario Damo
Original assignee: G.M.P. Spa
Priority date: 2003-02-05
Filing date: 2003-10-29
Publication date: 2004-08-19
Also published as: ITUD20030029A1; AU2003274473A1

Abstract

Plant and method for the production of polyurethane articles covered with a film. The plant comprises a molding apparatus (13) of the open-mold type and associated with press elements (29, 30) and a casting head (14) to cast the polyurethane. The plant further comprises a movable transport plane (28) suitable to pick up a segment of film and transfer it from a preparation and cutting position to a position wherein there is one molding apparatus (13), in order to position the segment of film in one of the elements of the mold, heating means able to heat the segment of film before it is inserted into the mold, and an automatically driven casting head (14) suitable to cast the polyurethane into the relative molding apparatus (13). The whole is arranged on a base (18) equipped with air suction means (42) cooperating with delivery means (39).

Description

"INTEGRATED PLANT FOR THE PRODUCTION OF ARTICLES MADE OF REINFORCED POLYURETHANE, RELATIVE METHOD AND POLYURETHANE ARTICLES THUS OBTAINED"

^•k - i -k - FIELD OF THE INVENTION

The present invention concerns a plant for the production of polyurethane articles, covered with a film, starting from polyurethane reinforced and/or enriched with fibrous material such as glass fibers, carbon fibers or fibers from other suitable material. The film used is of the thermoplastic type and can perform decorative and/or containing and protection functions.

The plant according to the invention comprises, as its main elements, an assembly suitable to prepare a segment of film, cut to size, an assembly suitable to transfer said segment of film from the preparation position to a relative molding apparatus, an assembly suitable to heat the film before it is inserted into the mold, at least a casting head suitable to introduce the polyurethane mixture inside an element of the relative molding apparatus, and one or more molding apparatuses cooperating selectively with said assembly to transfer the film and with said casting head and comprising respective press and mold elements.

The invention is applied in the field of molding polyurethane articles having aesthetic and mechanical characteristics such as to be compared with metal materials, in order to make components for earth moving machines, hoods, panels, etc.

BACKGROUND OF THE INVENTION Known methods to produce polyurethane articles differ from each other according to the base material used and the technique for finishing the surface of the article obtained. As far as the material is concerned, the use of polyurethane enriched with structural reinforcement fibers, particularly but not exclusively glass fiber, is more and more common and requested. The use of fibrous material combined with an integrating material such as polyurethane allows to obtain high quality of mechanical resistance, lightness and workability.

As far as finishing techniques are concerned, a first solution provides to make the article in a mold, remove it, and then subject it to a completion step that comprises at least trimming, surfacing, sanding and painting operations. This technique is very laborious, does not give satisfactory and repeatable results with acceptable levels of standardization and requires a high use of manpower and long execution times. Moreover, it limits the possibility of automating the production process and entails the need for purifiers and aerators, particularly in the sanding and painting steps .

It is also known to perform the painting step in the mold, but this technique leads to a poorer result in quality, and also to problems of repeatability, cleaning and setting up the components of the mold.

A second finishing technique provides to apply a covering and protective film in the mold, and then to introduce the mixture of polyurethane and reinforcing fibers into the open mold, as shown in EP-A-1.249.329.

In the event when polyurethane enriched with fibrous material is used as a base material, current processes are characterized by considerable operating problems that derive, at least partly, from the intrinsic characteristics of the material and the type of mold used.

In fact, the need to mix the polyurethane in the liquid state, during introduction, with fibers, and to cast, by means of a mixing head, the mixed material onto an element of an open mold, causes a considerable dispersion of the material that dirties the zones around the molding apparatuses and causes pollution often to a considerable extent .

The cast material, due to the speed of the jet, can splash outside the walls of the mold and contaminate the surrounding zones, with great problems for the operator who often provokes a further dispersion even outside the areas far from the operating areas as such. Moreover, to guarantee high quality of the articles obtained, the process requires that the elements of the mold are always in optimum conditions of cleanliness, and this entails considerable effort for the operators and long interruptions to the production process.

In known plants, the paved zones surrounding the molding apparatuses are often occupied by auxiliary members and devices, electric cables, pneumatic and/or hydraulic, pipes and conducts, etc., and this entails further difficulties for the operators. Moreover, known processes are in themselves slow and discontinuous because it is impossible to exploit a great part of the apparatuses during the time required for the polyurethane to polymerize inside the mold. For all these reasons, until now, this technology for the production of polyurethane articles has had a very limited development and been limited to mainly manual processes, not repeated and not standardized, very costly and with considerable problems concerning both the environment and also operating difficulties for the operators, connected to the surface finishing operations of the pieces. There are also considerable problems with the quality of the products obtained. Applicant has devised, tested and embodied the present invention to overcome these problems, which until now have limited the diffusion of this technology, and to obtain further advantages as shown hereafter. The purpose of the invention is to achieve a plant, and the relative method, suitable to produce, in repeated manner, with limited costs and times, with a high and standardized quality and with a high degree of automation of a large part of the operating steps, polyurethane articles made with reinforced polyurethane and covered on at least one face with at least a decorative film.

Another purpose is to achieve a compact, integrated plant, of limited size and complete with accessory elements to perform all the operations connected to finishing and completion of the works on the article.

A further purpose is to achieve a plant wherein optimum conditions are guaranteed with regard to cleanliness of the apparatuses and of the surrounding areas, and also an easy operativeness and conditions of safety for the operators. Another purpose is to optimize the production times, eliminating as far as possible pauses and downtimes .

A further purpose is to make the operations to change both the form of the article and also the color and format of the decorative film easy, quick and able to be automated, without requiring complex operations of disassembly and re-assembly of parts, nor particular use of manpower.

SUMMARY OF THE INVENTION The present invention is set forth and characterized in the main claims, while the dependent claims describe other characteristics of the main solution.

The integrated plant according to the present invention comprises, as its main elements: at least an assembly suitable to prepare, in a first position, a segment of decorative film, cut to size, and to transfer said segment of film, after it has been heated, from said first position to a second position wherein it is arranged on a suitable molding apparatus ; at least a molding apparatus arranged in said second position and comprising a relative press element and relative mold elements; and at least a mixing head able to introduce the polyurethane enriched and/or mixed with fibrous material into at least an element of said molding apparatus . The plant, also comprises first automated means able to pick up the segment of film from the first laying and cutting position and to transfer it onto a relative molding element, matrix or punch, arranged in a second position located laterally to the first position. According to one characteristic of the invention, the first automated means consist of at least a robotized manipulator arm. In a first solution, the manipulator arm is able to move on a higher plane with respect to the plane on which the segment of film is prepared and with respect to the relative molding apparatus. According to a variant, the manipulator arm is able to move along guides on the ground.

In one embodiment of the invention, the segment of film is subjected to heating and/or pre-forming before being positioned on the relative molding element. The heating and pre-forming on the one hand serve to reduce the time needed to thermoform the segment of film inside the mold, and on the other hand allow to exploit the downtimes caused by the time needed for polymerization of the polyurethane after it has been cast into the mold.

In another embodiment, the heating and/or pre-forming are carried out using a movable transport plane equipped with means to temporarily retain the segment of film and with incorporated heating means.

According to a variant, the film is heated using heating means outside the transport plane, for example heating lamps, such as infra-red, ultra-violet, or other suitable type, with which said transport plane is temporarily taken to cooperate.

According to one characteristic of the invention, the robotized manipulator arm is able to pick up the segment of film, or the transport plane that holds it, from the first preparation position, whatever it may be and with whatever orientation said segment be arranged, and to displace it to a second position cooperating with a relative element of the molding apparatus, in order to transfer the segment of film from said transport plane, if present, to said molding element. If the heating is performed by external means, the manipulator arm is suitable to position said transport plane in cooperation with said heating means, for example infra-red or ultra-violet lamps, until heating is completed, and then to insert the transport plane inside the molding apparatus where the forming of the film is completed and the molding cycle is performed.

According to another characteristic, the plant comprises at least second automated means able to move a relative casting head for casting the reinforced polyurethane into cooperation with a relative molding apparatus .

In a preferential embodiment, the second automated means comprise at least a second robotized manipulator arm able to displace the casting head into proximity with the molding apparatus wherein the introduction of the reinforced polyurethane is to be made and, when the introduction has been accomplished, to return the casting head to a stand-by position of non-interference.

In one embodiment, the second robotized manipulator arm is able to move on a higher plane with respect to the relative molding apparatus into which the polyurethane is introduced. According to a variant, the second robotized manipulator arm also moves along guides on the ground, made on the base on which the apparatuses of the plant are installed.

In one embodiment of the invention, the plant comprises two or more molding apparatuses, independent and autonomous of each other, advantageously three or more. The molding apparatuses are able to cooperate selectively, and on each occasion, with said first and second automated means, so that one or two robotized manipulator arms alone can be sufficient to perform all the functions necessary for the execution of the process even when there is a large number of molding apparatuses .

According to a characteristic of the invention, the press device associated with the elements of the mold is of the book-type, so it can open before the reinforced polyurethane is introduced; moreover, the press device can be of the rotary and/or pivoting type, for example of the type described and claimed in a parallel application in the name of the present Applicant, in order to assume at least a first working position facing towards the plant and a second position, wherein the piece is removed and the press device cleaned and/or serviced, facing towards the operator, which facilitates operativeness and guarantees safety for the worker. According to another characteristic, at least one of the elements of the mold is suitable to receive the polyurethane mixture from the casting head and has a conformation suitable to contain the mass of cast material and to reduce to a minimum the risk of leakages due to spurts and splashes of material; this mold is described and claimed in another parallel application in the name of the present Applicant.

In one embodiment of the invention, advantageously in the case of presses of average to small size, the entire plant is mounted on a base with relative higher structure inside which a suction channel is integrated, associated with an integrated suction system. The suction system allows to suck in and discharge the dirt and impurities that are generated during the work processes, in order to keep the paved zones around the apparatuses as clean as possible. The suction and ventilation system can be of the recycled type with a closed circuit or with an at least partial exchange of air with the environment. In the case that larger size presses are used, the plant can be arranged on the floor with relative foundations .

According to another variant, in the first position where the segment of film is laid and prepared, there is an automated apparatus to change the reel in order to replace an empty reel with a new one and/or to change the color and/or format of the film, as described and claimed in a parallel application in the name of the present Applicant.

According to another variant, downstream of at least one molding apparatus there is an automated device suitable to perform the mold-change operations when it is necessary to modify the figure of the article to be produced. BRIEF DESCRIPTION OF THE DRAWINGS These characteristics and advantages will become apparent from the following description of the preferential embodiment of the invention, given as a non-restrictive example with reference to the attached drawings wherein: - figs. 1-3 show respectively a view from above, a lateral view and a detail of a first embodiment of an integrated plant for the production of reinforced polyurethane articles according to the invention;

- fig. 4 shows a variant of fig. 3 ; - fig. 5 shows a variant of fig. 1;

- figs. 6 and 7 show, with a lateral view and a view partly from above, the suction and ventilation system with re-cycled air;

- figs. 8 and 9 show, with a lateral view and a view from above, the suction and ventilation system with air exchanged with the outside.

DETAILED DESCRIPTION OF THE DRAWINGS

With reference to figs. 1-3, the reference number 10 denotes generally a first form of embodiment of an integrated plant for the production of articles made of polyurethane reinforced with fibrous material and covered with a decorative film according to the invention.

The plant 10 comprises a first assembly 11 suitable to unwind, lay and cut to size a segment of decorative film; a molding assembly 12 comprising, in this case, four molding apparatuses 13, respectively 13a, 13b, 13c and 13d, substantially autonomous and independent from each other; and a casting head 14 suitable to introduce the mixture of polyurethane and fibers inside at least one element of a relative molding apparatus 13. There may be present a trimming and finishing assembly, not shown here.

Each molding apparatus 13 substantially consists of a press element that supports and positions a relative mold comprising at least a matrix and at least a punch.

The plant 10 also comprises, in this case, a heating and change assembly 16 for the frames made ready for version-change, using the method explained hereafter, a command zone 17 from which the operations performed by the plant 10 are controlled, coordinated and managed, and a general electric panel 36.

The plant 10 has a higher structure 15 above which the aforesaid electric panel 36 is installed and a skimmer 35 that feeds the casting head 14. On the higher structure 15 there is also a bridge-type guide 20 on which the automatic apparatuses described hereafter are displaced, in the embodiment shown here as an example. It comes within the field of the invention, although it is not shown here, that such apparatuses are mounted and move on guides on the ground, instead of along the bridge-type guide 20 shown.

Finally, the higher structure 15 supports the suction and air delivery systems and the pallets that contain the fiber that is fed to the casting head 14 in order to form the mixture with the polyurethane.

In the embodiment shown in figs. 1-3, the plant 10 comprises a base 18 on which are mounted columns 19 that support the higher structure 15 in the lower part of which the bridge-type guide 20 is mounted. The guide 20 extends in a higher position over the higher structure 15 along all four molding apparatuses 13a-13d. On the bridge-type guide 20 are mounted, free to translate linearly, a first robotized manipulator arm 21 and a second robotized manipulator arm 22. The function of the first manipulator arm 21, as will be explained hereafter, is to pick up the segment of film, heated or not, from the assembly 11 to unwind, lay and cut the segment of film, and to transfer it and position it on an element of the molding apparatus 13 operative at that moment. The function of the second manipulator arm 22, on the contrary, is to displace the casting head 14 on each occasion into correspondence with the specific molding apparatus 13 operative at that moment. Finally, the plant 10 comprises, in this case, an assembly 23 to support the reel of film in use at that moment, and an automated assembly 24 to change the version of the mold arranged downstream of the molding apparatuses 13. The assembly 23 to support the reel can comprise an automated system to change and replace the reel, and also to lay and cut to size the segment of film, as described and illustrated in a parallel application in the name of the present Applicant.

According to the invention, at the start of the operating cycle to form a polyurethane article, a first segment of decorative film is unwound from a reel 25 and laid on a work plane 26. When the preset measurement has been reached, cutting means 27 intervene on the film and cut a segment of the desired length. In the event that the segment of film must be heated and/or pre-formed before being transferred into one of the molding apparatuses 13, it is picked up by means of a heating plane 28, moved by the first manipulator arm 21, which is equipped with at least temporary retaining means, for example of the suction type. The heating plane 28 integrally includes heating means, for example with an electric resistance, and has at least a specific frame replaceable according to the type of size and figure to be made. A plurality of specific frames of different type and shape can be arranged in stand-by in the heating and change assembly 16, located at the side of the work plane 26.

According to a variant that is not shown here, the only function of the heating plane 28 is to transport the film, and it does not have integrated heating means. In this case, external heating means may be present, for example radiating lamps or similar, with which the film is taken to cooperate during its transfer from the work plane 26 to the relative molding apparatus 13.

The segment of film, during the heating step, can also be pre-formed upwards, for example by selectively driving vacuum means .

Once the segment of film has been positioned, possibly thermoformed and released in correspondence with an element of the _t mold, by means of a displacement of the first manipulator arm 21, the second manipulator arm 22 is driven in order to take the casting head 14 into correspondence with the mold. The casting head 14 is connected to the skimmer 35 to receive therefrom the mixture of polyurethane material and fibrous material. The head 14 casts the mixture of reinforced polyurethane over the segment of film, previously applied to one of the elements of the molding apparatus 13, to the quantity and with the distribution as desired.

The element of the mold on which the segment of film is positioned, and on which the mixture of polyurethane and fibers is then cast, advantageously constitutes the matrix element of the molding apparatus 13 and is "basin-shaped", as described in the parallel patent application in the name of the present Applicant, in order to reduce as much as possible the leakage of splashes or spurts of material during casting. When the delivery step is finished, the elements of the mold are closed and the polymerization of the reinforced polyurethane is started.

Simultaneously with the casting step, and also during the step of thermoforming the film and polymerizing the polyurethane, the first manipulator arm 21 has already picked up a new segment of film, possibly heated and/or pre-formed, and has positioned it in correspondence with another molding apparatus 13. When this step is finished, the casting head 14 also moves into correspondence with the other molding apparatus 13 in order to cast the mixture into the relative mold element. In this way, several cycles to form respective polyurethane articles, also having different characteristics from each other, can be temporally superimposed, which entails a considerable increase in flexibility and a notable reduction in downtimes .

According to the invention, each molding apparatus 13 is of the type openable like a book (figs. 3 and 4) and comprises, in this case, a first press element 29 functioning as a matrix bearer and a second press element 30 functioning as a punch bearer. The two press elements 29 and 30 can be opened with respect to each other by rotation on a pin 31.

The molding apparatus 13 is mounted on a base 32 that supports the press elements 29 and 30.

The press elements 29, 30 can rotate from a first position (left part of figs. 3 and 4), open towards the inside of the plant and cooperating with the mechanical members thereof, for example the arms 21 and 22, and a second position (right part of figs. 3 and 4), open towards the outside of the plant, a safe position for the worker 37. The first position is adopted at least during the positioning and thermoforming of the segment of film, and the casting of the mixture, while the second position is adopted at least during the removal of the molded article and in order to carry out works of inspection, cleaning and service of the elements of the mold itself.

In this case, the two positions are tilted by about 130°-140° with respect to each other. In the first position, moreover, the press element 29 functioning as a matrix bearer faces downwards and this facilitates cooperation with the casting head 14 that introduces the mixture inside. In the second position, the press element 29 functioning as a matrix bearer moves upwards, and this facilitates the removal of the article by the operator and protects the matrix from possible dirt that is generated during the cleaning step and/or the application of the anti-adhesive material on the punch. In this position the operations to clean the press elements 29, 30 are also facilitated, and the removal from said elements of impurities, fragments, dross and similar. The low position of the press element 30 functioning as the punch bearer also facilitates the possible positioning of inserts . The plant 10 is equipped (figs. 6 and 7) with a closed circuit suction and ventilation system that comprises suction channels 42 arranged inside the base 18, connected to suction systems 33. The plant also comprises delivery channels 39 mounted in a higher position on the higher structure 20. Advantageously a suction channel 42 is provided in correspondence with each of the molding apparatuses 13.

Before being sent to the relative delivery channels 39, the air sucked in is subjected to filtration by means of suitable filter systems 38.

The variant shown in figs . 8 and 9 provides that the suction and ventilation system has an exchange of air with the outside. For this purpose, the suction systems 33 are connected, by means of relative filter systems 38, to chimneys of which one 40a sucks in fresh air from the outside so as to send it, after a filter treatment, to the respective delivery channels 39, while the other 40b expels to the outside, after filtering, the air sucked in by the suction channels 42.

In this case too, advantageously, there is a suction channel 42 for each of the molding apparatuses 13.

The suction and ventilation system is suitable to convey the air and the dirt along the perimeters of the molding apparatuses 13, so as to guarantee that all the dirt, due to the splashes, the fibrous material and the residue deriving from cleaning the molding apparatuses 13, is conveyed towards the filter systems 38. The variant shown in figs. 4 and 5 refers to the case when molding apparatuses 13 of a larger size are used, and provides that the plant is arranged on the ground in a containing pit 41 with relative foundations. In these figures, the same reference numbers represent the same components as those already described with reference to the previous figures .

In this embodiment, instead of outside the base 18 as in fig. 1, the version-change carriage 24 is arranged between two contiguous molding apparatuses 13. The suction channels 42 are arranged in the pit 41.

It can be seen that with the plant according to the invention, which exploits aerial movements and integrated channels, the paved zones surrounding the molding apparatuses 13 are unencumbered and therefore can be cleaned and restored easily and quickly. This facilitates the operativeness of the workers and makes every intervention easier and quicker to do. The extreme cleanliness that can be guaranteed during the execution of the processes allows to ensure limited contamination and hence a high quality of the finished article.

If the movements occur with guides arranged on the base 18, they in any case define obligatory paths which delimit the spaces that can be dirtied and/or contaminated by the movement of the apparatuses .

The use of special molds and tilting presses not only allows the process to be partly automated, but also guarantees optimum safety conditions for the workers and extreme flexibility of the entire process, and makes the changes of set-up and format easy and rapid.

Claims

CLAIMS 1. Plant for the production of polyurethane articles covered with a thermoplastic film, starting from polyurethane reinforced and/or enriched with fibrous material, comprising at least a molding apparatus (13a-13d) of the open-mold type and associated with press elements (29, 30) and a casting head (14) to cast the reinforced polyurethane into said open mold, and also comprising means able to arrange and position on each occasion a heated segment of said film in said mold, characterized in that it comprises a movable transport plane (28), associated with first automated means (21) , suitable to pick up said segment of film and transfer it from a first preparation and cutting position to a second position located laterally to said first position wherein there is said at least one molding apparatus (13a-13d), in order to position said segment of film in one of the elements of the mold, heating means able to heat said segment of film before it is inserted into the mold, and at least an automatically driven casting head (14) suitable to cast the reinforced polyurethane into the relative molding apparatus (13a-13d) , the whole being arranged on a base (18) equipped at least with air suction means (42, 33) cooperating with delivery means (39) .

2. Plant as in claim 1, characterized in that said heating means are integrated in said movable transport plane (28) .

3. Plant as in claim 1, characterized in that said heating means are autonomous and independent from said movable transport plane (28) and comprise heating elements such as lamps or suchlike.

4. Plant as in claim 1, characterized in that said movable transport plane (28) is able to move on a higher plane with respect to the laying and cutting plane (26) , where the segment of film is arranged, and with respect to said molding apparatus (13a-13d) .

5. Plant as in claim 1, characterized in that said movable transport plane (28) is able to move on guides made on said base (18) .

6. Plant as in claim 3, characterized in that it comprises a heating and change assembly (16) , arranged at the side of an assembly (11) to prepare the segment of film, in order to heat transport planes (28) not in use and possibly to replace at least part of said movable transport plane (28) .

7. Plant as in any claim hereinbefore, characterized in that it comprises second automated means (22) able to move said casting head (14) for casting the reinforced polyurethane mixture into cooperation with a relative molding apparatus (13a-13d) , said second automated means (22) being functionally coordinated with the means to drive said movable transport plane (28) in order to introduce said polyurethane mixture immediately after the segment of film has been inserted into the relative molding apparatus (13a-13d) .

8. Plant as in claim 7, characterized in that said second automated means (22) are able to move on a higher plane with respect to the relative molding apparatus (13a-13d) .

9. Plant as in claim 7, characterized in that said second automated means (22) are able to move on guides made on said base (18) .

10. Plant as in claims 1 and 8, characterized in that said first and said second automated means each comprise at least a manipulator arm (21, 22) able to move along a bridge-type guide (20) arranged higher in cooperation with the position of said molding apparatuses (13a-13d) .

11. Plant as in any claim hereinbefore, characterized in that it comprises, downstream of at least one molding apparatus (13a-13d), an automated device (24) able to perform mold-change operations when it is required to modify the figure of the article to be made.

12. Plant as in claim 1, characterized in that it provides a closed circuit circulation of air.

13. Plant as in claim 1, characterized in that it provides the at least partial exchange of air with the outside environment by means of chimneys (40a, 40b) for the suction/expulsion of air, connected with the outside.

14. Method for the production of polyurethane articles covered with a decorative film starting from polyurethane reinforced and/or enriched with fibrous material, characterized in that it provides at least:

- a first step wherein a segment of film is prepared and cut to size in a first preparation and cutting position;

- a second step wherein said segment of film is transferred from a movable transport plane (28) to a .second position, located laterally to said first position, in cooperation with at least one press element (29, 30) of a molding apparatus (13a-13d) to be positioned therein and thermoformed;

- a third step wherein a casting head (14) for casting a polyurethane mixture is displaced in order to introduce said polyurethane mixture into at least one of said press elements (29, 30) ;

- a fourth step wherein the mold is closed in order to polymerize and mold the polyurethane;

- a fifth step wherein the mold is opened and the molded piece discharged by means of positioning the molding apparatus (13a-13d) in a discharge position, different from the position adopted by said molding apparatus (13a-13d) at least during the step when the polyurethane is introduced.

15. Method as in claim 14, characterized in that the segment of film is subjected to heating and possible preforming, before being positioned in cooperation with one of the press elements (29, 30) .

16. Method as in claim 14 or 15, characterized in that during the steps of thermoforming a first segment of film and/or of introducing the mixture by means of said casting head (14) and/or of polymerizing the polyurethane in a relative molding apparatus (13a-13d) , at least a second segment of film is prepared in said first preparation and cutting position, possibly heated and then transferred to said second position in cooperation with another molding apparatus (13a-13d) .

17. Method as in any claim from 14 to 16 inclusive, characterized in that at least during the step of polymerizing the polyurethane in a relative molding apparatus (13a-13d) , the casting head (14) is positioned in cooperation with another molding apparatus (13a-13d) to perform the introduction of the polyurethane therein.

18. Articles made starting from a mixture of polyurethane and fibrous material made in the plant and using the method as in any one or other of the previous claims .