NZ222816A

NZ222816A - Manufacturing composite article by extruding plastic material into outer cover

Info

Publication number: NZ222816A
Application number: NZ222816A
Authority: NZ
Inventors: Jean-Patrick Briand; Dominique Choulier
Original assignee: Gunther Sa
Priority date: 1986-12-04
Filing date: 1987-12-04
Publication date: 1992-08-26
Also published as: AU612995B2; DK163351B; ES2022424B3; KR880007216A; MY104312A; EP0270462A1; BR8706566A; ATE62864T1; DK163351C; PT86291A; DE3769607D1; EP0270462B1; DK635987A; IL84715A0; IL84715A; AU8213287A; DK635987D0; PT86291B; ZA879134B; JPS6485714A

Abstract

The said article, solid or hollow, comprises a core 1 and an outer sheath 2 which surrounds at least once the said core and firmly adheres thereto. The process consists: in conforming at least one strip of flexible material around a stationary hollow element 20 to form the sheath 2; in continuously driving the sheath 2 thus formed towards the end of the stationary hollow element; and in continuously dispensing from a tank 25, 27, where it is fluid or pasty, the material forming the core 1 into the stationary hollow element, from one end of the latter towards the said free end, in order that, on exiting the hollow element, the said material is received into the mould which the sheath 2 constitutes and spreads out therein on cooling and on adhering to the sheath on exiting the hollow element. The composite article obtained is applicable in the packaging, civil engineering, agricultural and insulation industries. <IMAGE>

Description

<div class="application article clearfix" id="description"> "2 28 Priori* r Ocas'*)■ <L> I 2 ^ | COP^?' . r ;:;or" u - :• i \-j j , P**.,*:TV.-" 2 "6 &U& m I ~".L , >Jv < T" ■i. . -r • Patents form No 5 PATENTS ACT 1953 Number Dated COMPLETE SPECIFICATION PROCESS AND APPARATUS FOR MAN'L'FACTURING A COMPOSITE ARTICLE OF CONSTANT SECTION COMPRISING A CORE AND AN OUTER COVER, AND COMPOSITE ARTICLE RESULTING THEREFROM kWE GUNTHER S.A., a French company of 53, rue ce la Papet 70800 Fontaine Les Lexeuil, France do hereby declare the invention for which Wwe pray that a Patent may be granted to roe/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 1 - (followed by pace la) ia *' 2 8 The present invention relates, in particular but not sx-5 clusivelv, to the continuous manufacture of a solid or hollow composite article of constant section, said article comprising a core and an outer cover which extends arounc at least once said core and stroncly adheres to the latter. The present invention therefore provides a process and an 10 apparatus for manufacturing such a composite article, and any composite article resulting from this manufacture. The invention is particularly, but not limitatively, applicable to articles of this type which are used for packaging, in particular for its protection and its reinforce-15 ments, for civil engineering, in signalling and coffering, for the furniture industry, for agriculture and for insulation - A first object of the invention is to provide a composite article of the aforementioned type which has interesting me-20. chanical and dimensional characteristics, even with a very-low apparent density, owing to the continuity of the cover, on one hand, and its assembly on the core, on the other hand, which imparts to the article a very high inertia. Consequently, owing to its rigidity, the article can support large 25 axial and racial loads. An other object of the invention is to provide an article of the type in question which has excellent resistance at low and hich ternoeratures, to exterior J** 2 ?22S 16 acer.is such as huraici-y ar.c chemical products, to shocks, the outer cover acting under the circumstances as a screen protecting the core, irrespective of the material from which it is mace, even if thermoplastic materials are employee in this 5 respect. Another object of this invention is to provide an article of the type in question which may be manufactured simply and economically anc which, when finished, can be worked and associated with other products according to the traditional 10 processes of machining, drilling, nailing, stapling, screwing or adhesion for example. It is already known to manufacture and employ composite section articles formed by a core of thermoplastic material which has or does not have a filler, and an outer cover which 15 is usually of flexible material and entirely and continuously expends around said core by the overlapping of all irs longitudinal sices and which protects said core by association wieh the latter by total and permanent adhesion. Such composite section articles are described in British patent specification No 2049540, New Zealand patent specification No 204,515, anc US-A-4,564,437. According to GB 2049540, the core is formed from a synthetic thermoplastic material distributed in particles or granules so as to form a mat, this mat is heated to the softening point of 25 the thermoplastic material by conveyinc it through an oven, anc finally the softened mat is compressed after having enveloped it in one or a plurality of sheets of flexible material Teed under the n.at and around ?223 the mat so that they completely envelope and adhere thereto at the moment of compression. According to the New Zelanc patent specification No 204515, the ccr is formed from a continuously fed thermoplastic material, m the form of a hot anc soft rod, by an extruder, .through an injection press or any other similar device capable of heating the thermoplastic material and bringing it to its softening temperature, then this rod is taken up by one or more sheets of a flexible material which support it anc the rod-sheets assembly is conveyed to a calendar for, by pulling on the sheet or sheeets simultaneously, continuously enveloping the rod with the sheet or sheets, and compressing the assembly while the thermoplastic material is still sufficiently hot so that it strongly and definitively adheres to its cover. In respect of the two aforementioned manufactures, it is clear that composite section article obtained is of a relatively high density since there is a compression of the thermoplastic material in the course of the final operations consisting in causing the core to adhere to its cover. Another of the essential objects of the invention is to provide a composite section article which has, subsequent to its realization, a very low apparent density between 10 kg/nJ and 500 kg/m^, preferably in the neighbourhood of 50 kg/m"^. Patent US-A-4,554,48/ describes a process and an installation for manufacturing such a composite section article having a low apparent density, in the form of a tube. The mate- •4 22 2 8 1 6 rial constituting the core of this tube is a foam of an insulating material between an inner cover and an outer cover of paper. To manufacture such a tube, the inner cover is first of all made by winding a banc of paper around a solid or hoi -5 low cylinder, then the outer cover is started to be formed by introducing another band of paper in a sleeve whose longitudinal axis is coincident with that of the cylinder. The material which will expand between the two sheets of paper to form the core is introduced at the upstream end of the sleeve 10 in a region where the outer cover of paper is therefore ne cessarily not yet closed. This manufacturing technique consequently presents various drawbacks: the material which will constitute the core cannot be partly gaseous, otherwise the gas will escape; this material 15 is therefore necessarily liquid or pasty, and consequently it concerns exclusively and limitativelv polyurethane, as the polyurethane expands between an already-formed inner cover and an outer cover in process of being formed, the sleeve against which said outer cover bears must necessarily 20. have a length equal to the length travelled through by the tube being formed up to the final expansion of the foan; consequently, if, as is case, the sleeve is short, the speed of displacement of the tube being formed is slow; indeed, if it is desired to increase the speed, the length of the sleeve 25 must also be increased in the same proportion, and this is quickly limited by problems of size and the difficulties of manufacturing a sleeve which would have to have a length of 22 2 8 1 several tens of metres. The present invention therefore first of all provides a process for manufacturing a solid or hollow composite article of constant section comprising a core anc a cover which ex-5 tends around at least once said core and strongly adheres to said core, said process comprising: shaping at least one band of flexible material around a fixed hollow element so as to constitute the cover; continuously driving the cover thus formed toward the free end of the fixed hollow element; ana 10 continuously distributing from a reserve, where it is fluid or pasty, the material for constituting the core in the fixed hollow element, from one end of the latter towards said free end, so that said material when it issues from the hollow element is received in the mould constituted by the cover anc 15 is developed therein while cooling anc adhering to the cover upon its emergence from the hollow element. According to this technique, the cover is completely shaped before receiving the material constituting the core; in other words, the cover performs a function of a mould in 20 which the material constituting the cooled core hardens and is developed. The indicated drawbacks of the manufacture of the tube disclosed in the patent US-A-4,554,487 are eliminated. Indeed, as the material constituting the core is introduced in 25 a mould which is already completely closed, it is possible to work with materials which, in order to expand, require to be supplied with a gas in suspension in the material; it is even <? 5 —N 10 15 20 22 2 8 1 possible to use a gas uncer high pressure; for example, to form the expanded material of the core, the invention permits the use of polyethylene, polypropylene, polystyrene or polyvinyl chloride supplied with a neutral gas such as freon which, in expanding, will form in the material a structure having open or closed cells, as the case may be. Furthermore, also owing to the fact that the mould is already closed in the region where the material which will expand is introduced, the cover does not need to be surrounded by a protective sleeve; the installation is therefore less space consuming and moreover permits operating at high speed. Three other advantages of this technique result from the fact that: it is possible to operate at very high speeds, on the order of 50 to "00 m/min owing to the fact that the article is driven by its cover while never affecting the material constituting its core; a non-adherent finished product is delivered if the outer sice of the cover is originally chosen not to be adhesive; it avoids the necessity to cool the core, irrespective of the material from which it is mace and irrespective of the temperature at which it is fed in the liquid or pasty state from its reserve supply. During its manufacture, the composite article is advantageously driven by a thrust or a traction exerted on the cover in a region located upstream of the free outlet end of the fixed hollow element- Thus, the driving is achieved by 22 2 8 1 6 exclusively acting on the cover in a region where moreover it is shaped and maintained in this shape by the fixed hollow element. The material constituting the core is therefore not directly subjected to the drive but only indirectly, when it 5 opens onto the mould formed by the cover. In other words, the driving may occur at maximum speed tolerated by the cover without being torn, which speed is very distinctly higher than the maximum speed that the material of the core can tolerate without rupture. 10 After its manufacture, the composite article is advanta geously cut to the required length by a cutting tool acting on the downstream sice of the free outlet end of the fixed hollow element. According to a first manner of carrying out the inven-15 tion, the band is presented longitudinally relative to the fixed hollow element anc its longitudinal edges are progressively formed over towards each other for overlapping purposes . According to a second manner of carrying out the inven-20. tion, the band is presented obliquely relative to the axis of the fixed hollow element so as to be wound in a helix around said hollow element. According to a first design variant, there is used as the material constituting the core an expanded material having 25 open or closed cells, resulting from the transformation of a thermoplastic material in association with a nucleation agent, for example a gas. s 22 2 8 1 According to a second design variant;, the material constituting the core is produced from at least two constituents and these two constituents are mixed inside the fixed hollow element in proximity to its free end, each constituent being 5 fed in the fixed hollow element in the liquid or pasty form from a reserve supply placed on the upstream side of said fixed hollow element. The present invention also provides an apparatus for manufacturing a composite article having a constant section and 10 comprising a core and an outer cover which extends around at least once said core and firmly adheres to the latter, said apparatus comprising means for continuously feeding at least one band of flexible material anc means for continuously feeding from a reserve supply the material constituting the core 15 which is then fluid or pasty so as to put it in contact with the band or bands, saic apparatus comprising: a fixed hollow element for receiving each banc on its outer surface; means for shaping each band around the fixed hollow element anc thus constituting the cover; means for continuously driving 20 the cover thus formed toward the free end of the fixed hoilew element; and means for causing the material constituting the core to pass from the reserve supply to the free end of the fixed hollow element, through said element, and for feeding said material inside the mold that the cover constitutes so 25 that it is developed therein while cooling anc adhering to the cover as soon as it issues from the hollow element. Means for driving the composite article, by exerting a a 22 2 8 thrust or a traction thereon, are advantageously located on the upstream sice of the free end of the fixed hollow element anc, when these driving means operate by exerting a traction on the cover, they preferably extend well beyond the fixed 5 hollow element at its free end. In the case where the cover is in the form of one or more longitudinally distributed bands, the means for shaping each banc are constituted by a fixed guide having an evolutive profile, said guide being capable of receiving the band in a 10 longitudinal position relative to the fixed hollow element anc progressively forming over the edges of the band towards each other until they are made to overlap each other. In the case where the cover is formed by at least one helical banc, the shaping mear.s ar.c the banc driving means are 15 formed by a movable belt or the like which applies the helical band against the fixed hollow element and urges it axial-ly toward the free enc of the latter. According to an advantageous variant, means are provided for applying an adhesive on at least one edge of the band be-20. fore it is shaped. According to another variant, the apparatus may comprise, at the end of the fixed hollow element, means for forming at least one cavity inside the composite article to be delivered. According to still another variant, the apparatus may 25 include cover aspirating means which cooperate with driving means. Depending on the material chosen to constitute the core, 22 2 8 1 the apparatus may comprise means for distributing, inside the fixed hollow element:, a mixture of thermoplastic material comprising a nucleation agent, for example a gas, capable of forming a foam having open or closed cells upon its expansion; as a variant, it may include means for mixing all the constituents of the material constituting the core, said means being preferably disposed in proximity to the free end of the fixed hollow element- The present invention thirdly provides a solid or hollow composite article of constant section intended for various uses and in particular a product of elongated shape such as a plate or section member of the type comprising a core and an outer cover extending around said core at least once and firmly adhering to said core, said article being obtained from the process such as that described hereinbefore - For example, the density of the core, and consequently the density of the article, is between about TO Xg/cu m and 500 Xg/cu m, the preferred value being in the neighbourhood of 50 Xg/cu m. Accorcing to the envisaged application, the composite article may be in the most diverse forms, for example in the form of a cylinder, a slat, a panel or a slab, anc have the most diverse sections, for example, circular, oval or polygonal or square, rectangular, hexagonal or octagonal. The composite article according to the invention may have a solid section that may also be of a lightened section with a centre cavity or peripheral cavities. The material forming the core may be of any material or assembly of materials having, after it or they have been employed, a very low apparent density, and advantageously it belongs to the group constituted by cellular, alveolar or ex pandec thermosetting and thermoplastic materials, in particu iar polythylene, polypropylene, polystyrene, polyvinyl chloride, polyurethane, by fibrous materials, in particular wood or paper cellulosic fibres which are assembled or agglomerated, or by recycled materials and combinations thereof. The cover is constituted by a basic material in the form of a flexible sheet preferably supplied in the form of a ver long band, said material belonging to the group constituted by paper, light cardboard, textile materials, synthetic mate rials and in particular film thermoplastics, non-woven, natu ral or synthetic fibrous materials, and by any combination thereof, for example by a complex itself obtained by assccia tion of a plurality of the aforementioned materials or by a composite sheet of the type formed by a thermoplastic matrix reinforced with threads, fibres or a trellis. It is also possible to resort to the use of complexes which themselves come from the association of materials having a low apparent density. Another possibility resides in covering the cover, over a part or all of its outer surface, with an expanded foam. According to a second manner of proceeding which was pro posed for the process mentioned hereinbefore, the composite article obtained has an outer helically wound cover. 12 22 2 8 -s In order to give a better explanation of the present invention, there will now be described/ by way of purely illustrative and non-limitative examples, various embodiments with reference to the accompanying drawings in which: 5 Figs, i to 6 are diagrammatic cross sectional views of various sections of a composite article - which are section members or plates - which may be produced by the process according to the invention, Figs. 7 to 12 are perspective views diagrammatically sho-10 wing various arrangements of a cover or covers, Fig. 13 is a diagrammatic side elevational view of an apparatus according to a first embodiment for manufacturing the composite article according to the invention, Figs. 14 to 15 are diagrammatic cross sectional views of 15 the apparatus of Fig. 13, respectively taken on lines XIV- XIV, XV-XV and XVI-XVI, Fig. 17 is a longitudinal sectional view of the apparatus taken in the plane of Fig. 13, Fig. 18 is a diagrammatic elevational view of an appara-20 tus according to a second embodiment for manufacturing the composite article, Figs. 19 and 20 are diagrammatic cross sectional views of the apparatus of Fig. 18, taken on lines XIX-XIX, XX-XX, respectively, anc 25 Fig. 21 is a diagrammatic longitudinal sectional view ta ken in the plane of Fig. 18 of the apparatus according to the second embodiment. 5 '—v 10 15 20 22 2 8 The composite section article according to the invention which, depending on its shape and constitution, may be used in the most diverse applications, comprises, on one hanc, a core 1 constituted by a material advantageously having low density and, on the other hand, an outer cover 2 which lonci tudinallv extends around at least once the core 1 and firmly adheres to the latter. By way of non-limitative examples, the core 1 may be for mec by a cellular, alveolar or expanded thermosetting or thermoplastic material, in particular polyethylene, polypropylene, polystyrene, polyvinyl chloride or polyurethane, a fibrous material, in particular based on wood or paper cellu losic fibres assembled or agglomerated, a recycled material which was initially intended to be scrapped, or any combinations of these materials. Also according to the applications, the material constituting the core may be flexible, rigid or semi-rigid, the co re being solid or, on the contrary, having a cavity, for example at its centre, or a plurality of cavities close to its periphery whereby the article is still further lightened Also by way of example, the density of the core 1 is advantageously low ana may be between 10 Xg/cu m and 500/Kg cu m, with a preferred value of about 50 Kg/cu m. As concerns the material constituting the cover 2, it is also chosen in accordance with the considered application. For example, this material may be paper, light cardboard, a textile material, a synthetic material, in particular a 5 10 15 20 22 2 8 1 6 thermoplastic material, a non-woven, natural or synthetic fibrous material or a combination of these materials. Thus, the cover is always constituted by a basic material which is in the form of a flexible sheet which may be supplied in bancs of very great length. Generally, the cover 2 is constituted by at least one solid or aoertured sheet. The cover has at least one layer of material but, depending on the envisaged application, it is not excluded to provide a plurality of layers which are at least partly superimposed. In most of the applications of the composite article according to the invention, the latter is in the form of a section member of constant section. This section may be cylindrical, in particular having a circular base, oval or polygonal, for example square, rectangular or octagonal. This section may have an axis of symmetry but it may also be of an uneven complex shape and be for example in the shape of an L, T, K the branches of which are equal or unequal. The article according to the invention may also be for example in the form of a slat, panel or a slab. Figs. 1 to 6 show a few examples of the cross section of the composite section article according to the invention. In Fig. 1, the cross section is circular; in Fig. 2, the cross section is a very flattened oval corresponding, for the article, to a slat, a panel or a slab; in Fig. 3, the cross section is rectangular; in Fig. 4, the cross section is 5 10 15 20 22 2 8 1 octagonal; and in rig. 5, the cross section is L-shaped. In rigs. 1 to 5, the core 7 is solid whereas, in Fig. 5, the core 1, which has been shown to be of circular shape by way of example, has a cavity 3, for example also circular and located at its centre. In the embodiment of Fig. 6, the composite article may comprise a longitudinal slot 4 shown in cot-dash lines, which connects the inner cavity 3 to the exterior, for example for the passage of an element, in particular a pipe in the case of the application to insulation. The core may also have close to its periphery a plurality of cavities 3 which will contribute to the lowering of the apparent density of the article without really diminishing its mechanical characteristics. Figs. 7 to 12 show a few embodiments of a composite article according to the invention as concerns the arrangement of the outer cover 2, for various cross sectional shapes. In Fig. 7, the cross section is rectangular and the cover 2 is disposed longitudinally by extending around the core 7 once, its longitudinal edges 2a, 2b parallel to the axis of the profiled section being in slightly overlapping relation and being assembled by adhesion; in Fig. 8, the cross section is in the shape of a very flattened oval and the cover 2, which is still disposed longitudinally, extends around the cover 1 about twice, its outermost longitudinal edge 2b being adhered to the preceding coil; in Fig. 9, the cross section is rectangular and the cover 2 which extends longitudinally, is composed of four elements, namely: two planar elements 2c, 16 222816 2a which cover the large sices and two elements 2e, 2f which have a U shape and come to overlap the small sides and the longitudinal edges of the elements 2c, 2d; in Fig. 10, the cross section is rectangular and the cover 2, which is still 5 longitudinal, is formed by a plurality of superimposed layers which are angularly offset and are adhered to one another; in Fig. 11, the cross-section is circular and the cover 2 is constituted by a single helically wound layer; and, in Fig. 12, the cross section is again circular and the cover 2 is 10 formed by the superimposition of a plurality of helically wound bancs. In Fig. 71, and optionally in Fig. 12, the successive coils overlap one another so that their edges may be adhered. The composite article according to the invention has in-15 teresting characteristics in several respects. First of all, the continuity of the cover 2 anc the total and permanent assembly of the latter on the core 1 impart a very high inertia to the article; owing to its relative rigidity, the article can support axial ar.c racial loads; the cover imparts to the 2Q article very good resistance to shocks, even if the core 1 is fragile; by a judicious choice of the material constituting the cover 2, the article has a good resistance to heat, humidity anc/or chemical products; the article can be easily machined or worked in accordance with conventional techni-25 cues, for example drilled, milled, nailed, stapled, screwed or adhered; owing to the presence of the cover 2 and to the adherence of the latter to the core 1, the article has good 17 22 2 8 cohesion even if the core 1 is of low density anc has low cohesion; moreover, manufacturing dimensions can be obtained for the article with an excellent tolerance which is maintained over a period of time. 5 The cover 2 constitutes a mask for the core 7 which, for given properties, may therefore be constituted by a less noble anc cheaper material; this cover also constitutes a screen between the core 7 and the exterior, which is of particular interest in the case of in particular fcoc or like 10 industries; the cover 2 may be easily printed for decorative or identification purposes; finally, if the cover is chosen from a non-aggressive material, at least as concerns its cuter surface, it enables the article to be put in contact with any fragile product. The cover may also be coated on all or 15 a part of its outer surface with an expanded material. There will now be described with reference to Figs. 13 to 27, two variants of the process ar.c two apparatus for manufacturing the composite article according to the invention. According to the process, at least one band of flexible 20 material is shaped around a fixed hollow element so as to constitute the cover, the cover formed in this way is continuously driven toward the free end of the fixed hollow element and the material constituting the core is continuously fed from a reserve supply where it is stored or prepared 25 in a fluid or pasty state, toward the free end so that, at the outlet of the fixed hollow element, said material received still in the fluid and pasty state in the previously- 22 2 8 1 is formed cover is developed in saic cover and adheres thereto by cooling upon its exit from the fixed hollow element. In a first manner of proceeding shown in Figs. 13 to 17, given by way of an example of manufacture of a rectangular 5 sectioned article comprising a cover constituted by a longi tudinal band closed onto its self with a partial overlapping, and a core of an expanded thermoplastic material, the banc 2 is therefore presented longitudinally relative to the fixed hollow element and, in accordance with a new conventional 10 technique, its longitudinal ecces are progressively formed over toward each other so as to overlap. The band 2 is fed from a reel 5 which is driven in rotation by the traction exerted in the downstream direction on the cover 2. The banc is conveyed toward the upstream enc of a guide 5 having a 15 evolutive profile which progressively closes toward the downstream end and terminates in the form of a tube having a closed or substantially closed lateral wall. The guide 5 receives internally the fixed hollow element which is formed by a horizontal tube having a rectangular 20 section exactly congruent with that of the article to be produced. This tube is mounted at the outlet of a screw extruder 8 which includes in the known manner an outer sleeve 9 anc a conveyor screw 10 of the Archimedean screw type driven in rotation by a motor 11. At its upstream enc, the extruder 25 3 receives the starting material intended to constitute the core 1 from a hopper 12. In the vicinity of its outlet enc, the extruder may be fed with inert gas, for example freon, 19 22 2 8 1 from a source 13 by means of a pump 14. In the vicinity of the common downstream end of the guide 6 and rube 7, and partly overlapping this tube, there is pro-viced a traction station constituted by two endless belts 15 5 which rotate in opposite directions ar.c cooperate by their confronting opposed surfaces with the tubular cover 2 containing the core 1. On the downstream sice of the traction belts 15, there is provided a cropping station constituted by at least one crop-10 ping blade 15 which crops the article to the required length. There will now be briefly described the operation of the apparatus of Figs. 13 to 17. The material contained in the hopper 12, for example polyethylene, is continuously fed by the extruder 8 to the in-15 let end of the tube 7 conjointly with the inert gas from the reserve supply 13. During its transfer within the sleeve 9 by the screw 10, the polymer is melted by thermal conduction against the walls of the extruder anc it is intimately mixed with the gas. The screw 10 effects the homogenitation and 20 brings the viscous product to a high pressure level. The reafter, in the tube 7, the expansion of the gas produces a homogeneous formation of bubbles which are separated from one another by a thin layer of polymer. As it travels through the tube 7, the intimate mixture of molten polyethylene anc 25 gas progressively and slowly cools. At the same time, the band 2, for example of paper, is fed to the guide 5 from the reel 5 by the traction exerted by the endless belts 15- At 20 22 2 8 1 the outlet of the tube 7, through a die 31, the mixture of molten polyethylene and gas is discharged into the tubular cover 2 which has been progressively formed by the guide 6 having an evolutive profile. The traction belts 15 cause 5 both the discharge of the terminated article in the downstream direction, the traction on the paper banc fed by the reel 5 and the maintenance of the cover 2 against the action of stresses produced by the expansion of the polyethylene at the outlet of the tube 7. Furthermore, this station 15 e.nsu-10 res the regularity of the longitudinal discharge speed of the article 1, 2. When it comes in contact with the cover 2, the polymer firmly adheres to the inner surface of the cover. On the downstream side of the traction station 15, the cropping station crops the article to the desired length. The article 15 is then coolec naturally by the transfer of its heat to the surrounding atmosphere. Advantageously, the apparatus just described may further comprise: if the longitudinal edges of the band 2 when they have 20 been formed over are in a wide overlapping relation, a station 32 for applying adhesive at least on the outer surface of the longitudinal edge 2a which will be covered, or at least the inner surface of the longitudinal edge 2b which will overlap the edge 2a, said coating station 32 being cis-25 posed at the maximum distance in a position upstream of the downstream enc of the guide 6, a suction device 33 for maintaininc the outer surfaces of m 22 2 8 21 the cover 2 in close contact with the traction belts 15 as soon as they leave the hollow element 7, at the region where the polyethylene begins to be developed inside the cover. The process and apparatus illustrated in Figs. 13 to 21, 5 given as an example of the manufacture of an article of cir cular section comprising a cover formed by a banc wound in a spiral anc a core of polyurethane foam, will now be described. In this case, the band adapted to constitute the cover 2 10 is presented obliquely relative to the axis of the hollow fi xed element so as to be helically wound onto the latter. The apparatus comprises a station continuously supplying at least one banc from at least one reel 35. Starting at the reel 36, the band passes under an applicator 17 which applies 15 from a reserve supply IS and a pump 19, a film 35 of adhesive on at least a part of the future outer surface of the band or bands 2 which are thereafter conveyed obliquely and tangen-tiallv toward the outer surface of the fixed hollow element formed by a horizontal cylindrical tube 20. This coating 20 station is only brought into operation in the case where a plurality of paper bands overlap one another (Fig. 12) to form the cover 2, or in the case where a single band is wound onto the tube 22 with a partial overlapping of its edges; in the first case, all the bands receive an adhesive on their 25 outer surface except the most outer band and in the second case only the parts of the overlapping edges are coated with adhesive. 22 2 8 -> f The banc is urgec against the tube 20 and wound anc adhered onto itself by an endless belt 21, one portion of which envelopes for example the tube 20 on one turn. The belt 21 extends arcunc two roils 22, at least one of which is a cri-5 ving roil. At the same time as it winds the band helically onto the tube 20, the belt 21 axially urges the cover 2 thus formed toward the free end of the tube 20. The outside diameter of the tube 20 therefore very exactly gives the inside diameter of the cover 2, in shape anc dimension. 10 The tube 20 receives internally two conduits 23 and 24 for respectively supplying isocyanate anc poiyol. The iso-cyanate is delivered in the liquid state from a reservoir 25 by a metering pump 25. The poiyol is supplied, also in the liquid state, from a reservoir 27 by a metering pump 23. As 15 shown in Fig. 21, the conduits 23, 24 extend longitudinally to the free end of the tube 20 anc constitute, in this region, a head end mixture of isocyanate and poiyol which are supplied together into the helical cover 2 previously formed on the tube 20. As soon as they are put in contact, the iso-20 cyanate and the poiyol, metered by the pumps 26 and 28, produce a rapid reaction of polyaccition in the very interior of the cover 2, which easily resists the slight radial pressure resulting from the foaming. A cropping station comprising a motor 29 and a cutting tool such as a circular saw 30 is 25 located downstream of the free end of the tube 20 at sufficient distance therefrom to ensure that the foaming has terminated at the cropping moment. The motor 29 and the tool 30 iSSSk i 23 -2 2 8 1 6 are advantageously mounted on a sliaable device which accompanies the axial displacement of the article in the course of the cropping at a speed equal to the speed of advance of the article 1, 2. 5 It will be understood that other manners of carrying out the process and other embodiments of the apparatus, anc various variants may be envisaged without departing from the scope of the invention. Firstly, it is clear that some of the component elements of the apparatus of Figs. 13 to 17 may 10 be adapted without any difficulty to the apparatus of Figs. 18 to 21, anc inversely, in particular the means for feeding the material constituting the core 1, the means for cropping the finished article, the means for shaping the cover around the fixed hollow element 7 or 20, anc the means for driving 15 the article by a thrust or by a traction exerted on the cover 2. For producing a lightened article having a hollowed section, there may be provided a special die 31 provided with at least one solid core extending out of the tube 7 on a subs-20 tantial length anc diagrammatical!*/ represented in dotted li nes 34 in Fig. 17- The process and apparatus according to the invention are particularly interesting owing to the fact that the cover itself is used as a mould for forming the core, that the dri-25 ving of the article is achieved by a traction or a thrust exerted exclusively on the cover, that it is possible to operate at very high speeds easily exceeding 50 m/min, and that 24 "2 2 8 1 6 it: is unnecessary to cool the core, even in the case where the cover is of a thermoplastic material. The process anc the apparatus according to the invention are also interesting owing to the fact that they permit the 5 manufacture of any solid or hollow section or profiled mem ber, irrespective of the section of this section member and irrespective of the regularity of this section; it is indeed the outer section of the fixed element 7, 20, which is produced with the highest precision in the workshop, which deter-10 mines by equivalence the section of the section member 1,2 produced immediately on the downstream sice of the fixed element. The invention has many applications. For example, in the packaging field, the article according to the invention may 15 be used as a reinforcing, bracing, spacing, or wedging member or as a foot, a stud, or as a protective L-section member. In the case of civil engineering, the article according to the invention may be used as a coffer element, or as a signalling post. In the application in the furniture industry, 20 the article according to the invention may be used as a rein forcing element or a panel. In agricultural applications, it may be used as a prop or a post. The article according to the invention also has an interesting application in the field of thermal and/or phonic insulation. 25 Depending on whether it is intended for a single use or repeated uses, the article according to the invention may be formed basically from cheap ordinary materials, even 25 " 2 2 8 1 recovered materials which are recycled or materials based on more noble materials, in particular for high technology applications. It will be understood that the scope of the invention is 5 not limited to the embodiments or to the modes of application described and that various variants may be conceived without departing from the scope of the invention as defined in the appended claims. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> <L d. 26 WHAT WE CLAIM IS:

1. A process for manufacturing a composite article, said article comprising a core and an outer cover which extends at least once around said core and firmly adheres to said core, said process comprising: shaping at least one band of flexible material around a fixed hollow element so as to constitute the cover; continuously driving the cover thus formed around the fixed hollow element toward the free end of said fixed hollow element; and continuously supplying the material constituting the core in a fluid or pasty state, from a reserve supply through the fixed hollow element and toward the free end thereof, whereby at the outlet of the fixed hollow element said material is received in the closed mould constituted by the cover, upon its exit from the hollow element, and is developed therein by cooling and adhering to said cover.

2. A process according to claim 1, further comprising driving said article by a thrust or a traction exerted on the cover in a region located on the upstream side of the free outlet end of the fixed hollow element.

3. A process according to claim 1 or 2, further comprising cropping the article on the downstream side of the free outlet end of the fixed hollow element.

4. A process according to any one of claims 1 to 3, further comprising presenting the band or bands longitudinally relative to the fixed hollow element and progressively forming over the longitudinal edges of the band or bands so that said edges overlap each other.

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5- A process according to any one of claims 1 to 3, further comprising presenting the band or bands obliquely relative to the axis of the fixed hollow element so as to wind the band or bands helically around said fixed hollow element.

6. A process according to any one of claims 1 to 5, further comprising employing as a material constituting the core, an expanded material having open or closed cells coming from the transformation of a thermoplastics material in association with a nucleation agent.

7. A process according to claim 6, wherein said nucleation agent is a gas.

8. A process according to any one of claims 1 to 5, further comprising producing the material constituting the core from at least two constituents, mixing said constituents inside the fixed hollow element in proximity to its free end, each constituent being distributed in the fixed hollow element in the fluid or pasty state from a reserve supply placed on the upstream side of said fixed hollow element.

9- An apparatus for manufacturing a composite article comprising a core and an outer cover which extends around said core at least once and firmly adheres to said core, said apparatus comprising means for continuously feeding at least one band of flexible material, one fixed hollow element for receiving the band or bands and for shaping the cover from the band or bands, and means for continuously supplying the material constituting the core in a fluid or pasty state from a reserve supply, until said material is put in contact with the cover, said apparatus also having: means for receiving the band or bands and for shaping the band or bands around the fixed hollow element, for thus constituting the cover; means for continuously driving the cover thus formed

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around the fixed hollow element toward the free end of said fixed hollow element; and means for causing the material constituting the core to flow from the reserve supply to the free end of the fixed hollow element, through said element, and for distributing said material inside the closed mould constituted by the cover so that it is developed therein by cooling and adhering to said cover, wherein the article produced is of constant section.

10. An apparatus according to claim 9, further comprising means for driving the composite article placed on the upstream side of the free end of the fixed hollow element.

11. An apparatus according to claim 10, wherein the means for driving the composite article operates by exerting a traction on the cover and extends beyond the fixed hollow element at its free end.

12. An apparatus according to claim 10, wherein the means for driving the composite article operates by exerting a thrust on the cover-

13. An apparatus according to any one of claims 9 to 12,

further comprising means for cropping the composite article located on the downstream side of the free end of the fixed hollow element.

14. An apparatus according to any one of claims 9 to 13,

wherein the means for shaping the band or bands comprises a fixed guide which is capable of receiving the band or bands in a longitudinal position relative to the fixed hollow element and progressively forming over the edges of the band or bands towards each other until they are made to overlap each other.

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15- An apparatus according to any one of claims 9 to 13,

wherein the means for shaping and the means for continuously driving the band or bands comprises a movable belt or the like which helically lays the band or bands on the fixed hollow element and axially urges the band or bands toward the free end of the fixed hollow element.

16. An apparatus according to any one of claims 9 to 15,

wherein means are provided for applying an adhesive on at least one edge of the band or bands before the band or bands are finally shaped around the fixed hollow element-

17. An apparatus according to any one of claims 9 to 16,

further comprising, means at the end of the fixed hollow element for forming at least one cavity within the composite article to be delivered.

18. An apparatus according to any one of claims 9 to 17,

further comprising means for distributing inside the fixed hollow element, a mixture of thermoplastics material including a nucleation agent capable of forming a foam having open or closed cells upon the expansion thereof.

19. An apparatus according to claim 18, wherein said nucleation agent is a gas.

20. An apparatus according to any one of claims 9 to 17,

further comprising means for mixing all of the constituents of the material constituting the core.

21. An apparatus according to claim 20, wherein said means is disposed for cooperation in proximity to the free end of the fixed hollow element.

/ i £ A' >'

22. An apparatus according to any one of claims 9 to 21/ S

V

comprising means for producing suction on the cover which cooperates with said driving means. 11 JUfyfgg

30

23. A composite article when prepared by the process or apparatus of any one of the preceding claims, in comprising a core and an outer cover extending at least once around said core and firmly adhering to said core, wherein the density of the

3 3"

core is between substantially 10 kg/m and 500 kg/m , the material constituting said core belongs to the group constituted by polyethylene, polypropylene, polystyrene and polyvinyl chloride, and wherein the article is of constant section.

24. A solid or hollow composite article according to claim 23, wherein the density of the core is substantially 50 kg/m^.

25. A composite article according to claim 23, wherein the cover is constituted by at least one solid or apertured sheet-

26. A composite article according to any one of claims 23 to

25, wherein the cover has at least one layer of material.

27. A composite article according to any one of claims 23 to

26, wherein the composite article has a circular, oval or polygonal cross-section.

28. A composite article according to claim 27, wherein the composite article has a rectangular cross-section.

29. A composite article according to any one of claims 23 to

27, wherein the composite article is in the form of a cylinder, a slat, a panel or a slab.

30- A composite article according to any one of claims 23 to

29, wherein said core contains a cavity.

31. A composite article according to any one of claims 23 to

30, wherein said core is flexible.

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32. A composite article according to any one of claims 23 to 31, wherein the material constituting the core belongs to the group comprising cellular, fibrous, alveolar or expanded thermosetting or thermoplastics materials, fibrous materials and combinations thereof.

33. A composite article according to claim 32, wherein said thermoplastics material is polyethylene, polypropylene, polystyrene, polyvinyl chloride or polyurethane.

34. A composite article according to claim 32, wherein said fibrous material is wood or paper cellulosic fibres which has been assembled, agglomerated or recycled.

35. A composite article according to any one of claims 23 to 34, wherein the material constituting the cover belongs to the group constituted by paper, light cardboard, textile materials, synthetic materials, and combinations thereof.

36. A composite article according to claim 35, wherein the material(s) is(are) thermoplastics, non-woven, natural fibrous or synthetic fibrous materials.

37. A composite article according to any one of claims 23 to

36, wherein the cover is covered, on all or part of its outer surface, with an expanded foam.

38. A composite article according to any one of claims 23 to

37, wherein its outer cover is helically wound.

39. A process for manufacturing a composite article of constant section, substantially as herein described with reference to and as shown in the accompanying drawings.

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40. An apparatus for manufacturing a composite article of constant section, substantially as herein described with reference to and as shown in the accompanying drawings.

41. A composite article of constant section, substantially as herein described with reference to and as shown in the accompanying drawings.

ATTOr.r::vs r-cn THE APPLICANT

1

1 J UN-992^

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