AU612995B2 - Process and apparatus for manufacturing a composite article of constant section comprising a core and an outer cover and composite article resulting therefrom - Google Patents

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

THE COMMISSIONER OF PATENTS This form must be accompanied by either a provisional specification (Form 9 and true copy) or by a complete specification (Form 10 and true copy).

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I-L -YIIISCIILSill) LIIILIY-S t 56908 9 I- i I~C- -aan~a~; COMMONWEALTH OF AUSTRALIA f

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Patents Act 1952-1969 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int. Class Application Number Lodged Complete Application No.

Specification Lodged Published 0 Priority: .,Belated art: Name of Aoplicant: Address of Applicant: 0 Actual Inventors: ddrss forService: o Address for Service: TO BE COMPLETED BY APPLICANT GUNTHER S.A.

53, rue de la Papeterie, 70800 Fontaine Les Luxeuil, France Jean-Patrick BRIAND and Dominique CHOULIER care of COLLISON CO., 117 King William Street, Adelaide, South Australia, 5000, Australia Complete Specification for the invention entitled: "PROCESS AND APPARATUS FOR MANUFACTURING A COMPOSITE ARTICLE OF CONSTANT SECTION COMPRISING A CORE AND AN OUTER COVER, AND COMPOSITE ARTICLE RESULTING THEREFROM" The following statement is a full description of this invention, including the best method of performing it known to rneus: i_ cl~u- -lu 70800 ST LOU 11UR 3 EI E(S7gntureof ecarant) THE COMMISSIONER OF PATENTS. 0 0 l atu c art 84.94.8 S T6L 84.94.8 i (IMPORTANT Cross ohiygpplgY 4ggs in above Form.) *0/4524 A I I

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r -*l~o-~~lrm;Purrm~-M~ 0 0 a 0 0 1 00 0 0 0 0 O 0 00 PROCESS AND APPARATUS FOR MANUFACTURING A COMPOSITE ARTICLE OF CONSTANT SECTION COMPRISING A CORE AND AN OUTER COVER, AND COMPOSITE ARTICLE RESULTING THEREFROM The present invention relates, in particular but not exclusively, to the continuous manufacture of a solid or hollow composite article of constant section, said article comprising a core and an outer cover rhich extends around at least once said core and strongly adheres to the latter.

The present invention therefore provides a process and an LO 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 insula- S0 o o 0 oo 0 00 0 00 0 0 0 0 000 tion.

A first object of the invention is to provide a composite article of the aforementioned type which has interesting me- 2Q 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 axial and radial loads. An other object of the invention is to provide an article of the type in question which has excellent resistance at low and high temperatures, to exterior i I ~L iL1~_i A. ~T~~nru~r 2 agents such as humidity and 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 made, even if thermoplastic materials are employed in this respect.

Another object of this invention is to provide an article n of the type in question which may be manufactured simply and 00I 00 0 0 economically and which, when finished, can be worked and associated with other products according to the traditional o0 0 processes of machining, drilling, nailing, stapling, screwing or adhesion for example.

It is already known to manufacture and employ composite o 0 section articles formed by a core of thermoplastic material which has or does not have a filler, and an outer cover which o 015 is usually of flexible material and entirely and continuously 0 extends around said core by the overlapping of all its longic tudinal sides and which protects said core by association with the latter by total and permanent adhesion.

Such composite section articles are described in patents FR-A-2,455,968 FR-A-2,528,350 and US-A-4,564,487.

According to the document FR-A-2,455,968, 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 the thermoplastic material by conveying it through an oven, and finally the softened mat is compressed after having enveloped it in one or a plurality of sheets of a flexible material fed under the mat and around 3 the mat so that they completely envelope and adhere thereto at the moment of compression.

According to the document FR-A--2,538,350, the core is formed from a continuously fed thermoplastic material, in the form of a hot and 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 tem- :0~0 perature, then this rod is taken up by one or more sheets of a flexible material which support it and the rod-sheets as- 0 401 sembly is conveyed to a calendar for, by pulling on the sheet 000 or sheeets simultaneously, continuously enveloping the rod with the sheet or sheets, and compressing the assembly while 0 00 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 0 clear that composite section article obtained is of a relatiplastic material in the course of the final operations consisting in causing thet 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 U its realization, a very low apparent density between 10 Kg/cu m and 500 Kg/cu m, preferably in the neighbourhood of Kg/cu m.

Patent US-A-4,564,487 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 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 band of paper around a solid or hollow cylinder, then the outer cover is started to be formed by introducing another band of paper in a sleeve whose longituo dinal axis is coincident with that of the cylinder. The mate- O rial which will expand between the two sheets of paper to 0 0 0 form the core is introduced at the upstream end of the sleeve 000 in a region where the outer cover of paper is therefore necessarily not yet closed. This manufacturing technique con- 0000 sequently presents various drawbacks: 00 000the material which will constitute the core cannot be 0 0* partly gaseous, otherwise the gas will escape; this material ff is therefore necessarily liquid or pasty, and consequently it concerns exclusively and limitatively polyurethane, 0900 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 have a length equal to the length travelled through by the tube being formed up to the final expansion of the foam; 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 '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 0 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 and a cover which extends 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 o to constitute the cover; continuously driving the cover thus formed toward the free end of the fixed hollow element; and 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 00 end, so that said material when it issues from the hollow element is received in the mould constituted by the cover and 013 is developed therein while cooling and adhering to the cover A upon its emergence from the hollow element.

0 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 which the material constituting the cooled core hardens and is developed.

The indicated drawbacks of the manufacture of the tube disclosed in the patent tS-A-4,564,487 are eliminated. indeed, as the material constituting the core is introduced in 2S a mould which is already completely closed, it i5 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 6 possible to use a gas under 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 0 0Q and moreover permits operating at high speed.

00 Three other advantages of this technique result from the o fact that: ooa it is possible to operate at very high speeds, on the order of 60 to 100 m/min owing to the fact that the article is eo driven by its cover while never affecting the material consoa oo tituting its core; 0:00 a non-adherent finished product is delivered if the outer side 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 made 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 N. 7 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 opens onto the mould formed by the cover. In other words, the driving may occur at maximum speed tolerated by the cover 1: without being torn, which speed is very distinctly higher t than the maximum speed that the material of the core can to- I lerate without rupture.

'Oo After its manufacture, the composite article is advantageously cut to the required length by a cutting tool acting on the downstream side of the free outlet end of the fixed aa hollow element.

According to a first manner of carrying out the inven- 1 tion, the band is presented longitudinally relative to the I fixed hollow element and its longitudinal edges are progres- Ssively formed over towards each other for overlapping purposes.

According to a second manner of carrying out the inven- 2Q 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 open or closed cells, resulting from the transformation of a thermoplastic material in association with a nucleation agent, for example a gas.

8 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 fed in the fixed hollow element in the liquid or pasty form from a reserve supply placed on the upstream side of said fi-

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0 xed hollow element.

o The present invention also provides an apparatus for manufacturing a composite article having a constant section and .o S0 comprising a core and an outer cover which extends around at least cnce said core and firmly adheres to the latter, said apparatus comprising means for continuously feeding at least ao 0 one band of flexible material and means for continuously feeding from a reserve supply the material constituting the core 0J15 which is then fluid or pasty so as to put it in contact with the band or bands, said apparatus comprising: a fixed hollow element for receiving each band on its outer surface; means for shaping each band around the fixed hollow element and thus constituting the cover; means for continuously driving the cover thus formed toward the free end of the fixed hollow 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 that it is developed therein while cooling and adhering to the cover as soon as it issues from the hollow element.

Means for driving the composite article, by exerting a i, 9 thrust or a traction thereon, are advantageously located on the upstream side of the free end of the fixed hollow element and, when these driving means operate by exerting a traction on the cover, they preferably extend well beyond the fixed hollow element at its free end.

In the case where the cover is in the form of one or more S0 longitudinally distributed bands, the means for shaping each o band are constituted by a fixed guide having an evolutive profile, said guide being capable of receiving the band in a 110 longitudinal position relative to the fixed hollow element and progressively forming over the edges of the band towards i 0 each other until they are made to overlap each other.

i In the case where the cover is formed by at least one hei lical band, the shaping means and the band driving means are formed by a movable belt or the like which applies the helical band against the fixed hollow element and urges it axially toward the free end of the latter.

According to an advantageous variant, means are provided for applying an adhesive on at least one edge of the band bei 2Q 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 include cover aspirating means which cooperate with driving means.

Depending on the material chosen to constitute the core, i~ ~r C'C uU 1l. I A- I CL the apparatus may comprise means for distributing, inside the fixed hollow element, a mixture of thermoplastic material i 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 Sof the fixed hollow element.

The present invention thirdly provides a solid or hollow S 10 composite article of constant section intended for various i 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 10 Kg/cu m and 500 Kg/cu m, the preferred value being in the neighbourhood i i of 50 Kg/cu m.

S 20 According to the envisaged application, the composite ari tidcle may be in the most diverse forms, for example in the form of a cylinder, a slat, a panel or a slab, and 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.

-1 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 expanded thermosetting and thermoplastic materials, in particular 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 very long band, said material belonging to the group constituted by paper, light cardboard, textile materials, synthetic matea 04 rials and in particular film thermoplastics, non-woven, natu- ::lnor synthetic fibrous materials, and by any combination thereof, for example by a complex itself obtained by associaa tion of a plurality of the aforementioned materials or bya 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.

Accordi-g to a second manner of proceeding which was proposed for the process mentioned hereinbefore, the composite article obtained has an outer helically wound cover.

A 12 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: Figs. 1 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- 1 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 artiLcle according to the invention, Figs. 14 to 16 are diagrammatic cross sectional views of S, 15 the apparatus of Fig. 13, respective.y taken on lines XIV- Alf 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 apparatus 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, and Fig. 21 is a diagrammatic longitudinal sectional view taken in the plane of Fig. 18 of the apparatus according to the second embodiment.

j __rjl- ~iiiim miii ~iimIi Iii iI~rnuin~miiiii 1 flimm hi 1 n*i, 13 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 hand, a core 1 constituted by a material advantageously having low density and, on the other hand, an outer cover 2 which longitudinally extends around at least once the core 1 and firmly SR adheres to the latter.

By way of non-limitative examples, the core 1 may be formed by a cellular, alveolar or expanded thermosetting or ±0 thermoplastic material, in particular polyethylene, polypropylene, polystyrene, polyvinyl chloride or polyurethane, a fibrous material, in particular based on wood or paper cellulosic fibres assembled or agglomerated, a recycled material i which was initially intended to be scrapped, or any combinations of these materials.

Also according to the applications, the material consti- U; tuting the core may be flexible, rigid or semi-rigid, the core 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 and may be between 10 Kg/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 S -b L_ 14 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 bands of very great length.

Generally, the cover 2 is constituted by at least one soo lid or apertur. '-heet.

S* The cover has at least one layer of material but, depen- 0 o ding on the envisaged application, it is not excluded to pro- 0 1~0 vide a plurality of layers which are at least partly superim- 0 00 posed.

In most of the applications of the composite article aco a cording to the invention, the latter is in the form of a sec- D 0 tion member of constant section. This section may be cylin- 1o drical, in particular having a circular base, oval or polygo- 0 o nal, for example square, rectangular or octagonal. This secos tion 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, H 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 t octagonal; and in Pig. 5, the cross section is L-shaped. In Figs. 1 to 5, the core 1 is solid whereas, in Fig. 6, 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 dotdash lines, which connects the inner cavity 3 to the exte- 0 nior, for example for the passage of an element, in particuo lar a pipe in the case of the application to insulation. The TO core may also have close to its periphery a plurality of cab0 0 vities 3 which will contribute to the lowering of the apparent density of the article without really diminishing its 0 0*0 mechanical characteristics.

0' 0 0 V0 Figs. 7 to 12 show a few embodiments of a composite anti- 00 0 0 011 cle accr-rding to the invention as concerns the arrangement of 000000 0 the outer cover 2, for various cross sectional shapes. In 0.00 Fig. 7, the cross section is rectangular and the cover 2 is 00 disposed longitudinally by extending around the core 1 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 2d which cover the large sides 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 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 44 constituted by a single helically wound layer; and, in Fig.

:i 12, the cross section is again circular and the cover 2 is formed by the superimposition of a plurality of helically wound bands. In Fig. 11, and optionally in Fig. 12, the suc- '4 cessive coils overlap one another so that their edges may be 4 adhered, The composite article according to the invention has in- 04 teresting caatrsisin several respects. First of all, the continuity of the cover 2 and the total and permanent aso'0 sembly 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 and radial loads; the cover imparts to the 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 and/or chemical products; the article can be easily machined or worked in accordance with conventional techniques, 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 cohesion even if the core 1 is of low density and has low cohesion; moreover, manufacturing dimensions can be obtained for the article with an excellent tolerance which is maintained over a period of time.

The cover 2 constitutes a mask for the core 1 which, for given properties, may therefore be constituted by a less no- 1 33 ble and cheaper material; this cover also constitutes a 1 screen between the core 1 and the exterior, which is of pari ticular interest in the case of in particular food or like S -j 0 industries; the cover 2 may be easily printed for decorative M or identification purposes; finally, if the cover is chosen d :from a non-aggressive material, at least as concerns its outer surface, it enables the article to be put in contact with any fragile product. The cover may also be coated on all or S 5 a part of its outer surface with an expanded material.

II

There will now be described with reference to Figs. 13 to 21, two variants of the process and two apparatus for manufacturing the composite article according to the invention.

According to the process, at least one band of flexible 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 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- -a 18 formed cover is developed in said 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 sectioned article comprising a cover constituted by a longitudinal band closed onto its self with a partial overlapping, and a core of an expanded thermoplastic material, the band 2 t is therefore presented longitudinally relative to the fixed 4 hollow element and, in accordance with a now conventional 44 0o technique, its longitudinal edges are progressively formed over toward each other so as to overlap. The band 2 is fed 440 from a reel 5 which is driven in rotation by the traction oA exerted in the downstream direction on the cover 2. The band oo p is conveyed toward the upstream end of a guide 6 having a evolutive profile which progressively closes toward the gel downstream end and terminates in the form of a tube having a closed or substantially closed lateral wall.

The guide 6 receives internally the fixed hollow element which is formed by a horizontal tube having a rectangular 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 and a conveyor screw 10 of the Archimedean screw type driven in rotation by a motor 11. At its upstream end, the extruder 8 receives the starting material intended to constitute the core 1 from a hopper 12. In the vicinity of its outlet end, the extruder may be fed with inert gas, for example freon, A 1 r Ad. J 19 from a source 13 by means of a pump 14.

In the vicinity of the common downstream end of the guide 6 and tube 7, and partly overlapping this tube, there is provided a traction station constituted by two endless belts which rotate in opposite directions and cooperate by their confronting opposed surfaces with the tubular cover 2 containing the core 1.

On the downstream side of the traction belts 15, there is provided a cropping station constituted by at least one croplU ping blade 16 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 inlet 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 and it is intimately mixed with the gas. The screw 10 effects the homogenization and brings the viscous product to a high pressure level. The- I reafter, in the tube 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 and gas progressively and slowly cools. At the same time, the band 2, for example of paper, is fed to the guide 6 from the reel 5 by the traction exerted by the endless belts 15. At Al. 1 the outlet of the tube 7, through a die 31, the mixture of molten polyethylene and gas is discharged into the tubular jcover 2 which has been progressively formed by the guide 6 having an evolutive profile. The traction belts 15 cause both the discharge of the terminated article in the downstream direction, the traction on the paper band 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 ensures 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 5 is then cooled 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 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 disposed at the maximum distance in a position upstream of the downstream end of the guide 6, a suction device 33 for maintaining the outer surfaces of

A..

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. 18 to 21, given as an example of the manufacture of an article of circular section comprising a cover formed by a band wound in a spiral and a core of polyurethane foam, will now be described.

In this case, the band adapted to constitute the cover 2 "iO ~is presented obliquely relative to the axis of the hollow fixed element so as to be helically wound onto the latter.

.I The apparatus comprises a station continuously supplying 1 at least one band from at least one reel 36. Starting at the 4 i reel 36, the band passes under an applicator 17 which applies from a reserve supply 18 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 tangentially toward the outer surface of the fixed hollow element i formed by a horizontal cylindrical tube 20. This coating 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 outer surface except the most outer band and in the second case only the parts of the overlapping edges are coated with adhesive.

u A

AA

22 The band is urged against the tube 20 and wound and 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 around two rolls 22, at least one of which is a driving roll. 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 and dimension.

,i0 The tube 20 receives internally two conduits 23 and 24 for respectively supplying isocyanate and polyol. The isocyanate is delivered in the liquid state from a reservoir I> by a metering pump 26. The polyol is supplied, also in the I liquid state, from a reservoir 27 by a metering pump 28. As shown in Fig. 21, the conduits 23, 24 extend longitudinally to the free end of the tube 20 and constitute, in this region, a head end mixture of isocyanate and polvol which are supplied together into the helical cover 2 previously formed on the tube 20. As soon as they are put in contact, the isocyanate and the polyol, metered by the pumps 26 and 28, produce a rapid reaction of polyaddition 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 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 ~l ~Li~L- e~ _U L -L L i_- 23 are advantageously mounted on a slidable 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.

It will be understood that other manners of carrying out the process and other embodiments of the apparatus, and various variants may be envisaged without departing from the O, scope of the invention. Firstly, it is clear that some of o the component elements of the apparatus of Figs. 13 to 17 may be adapted without any difficulty to the apparatus of Figs.

18 to 21, and inversely, in particular the means for feeding o the material constituting the core 1, the means for cropping 0 00 0 o the finished article, the means for shaping the cover around the fixed hollow element 7 or 20, and the means for driving the article by a thrust or by a traction exerted on the cover 2.

s~u 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 substantial length and diagrammatically represented in dotted lines 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 driving 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 60 m/min, and that 244 it is unnecessary to cool the core, even in the case where W the cover is of a thermoplastic material.

The process and the apparatus according to the invention are also interesting owing to the fact that they permit the manufacture of any solid or hollow section or profiled member, 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 determines by equivalence the section of the section member 1, 2 produced immediately on the downstream side of the fixed element.

The invention has many applications. For example, in the packaging field, the article according to the inventicn may 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, the article according to the invention may be used as a reinforcing 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.

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 A 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 not limited to the embodiments or to the modes of .application described and that various variants may be conceived without o "o departing from the scope of the invention as defined in the 00 appended claims.

o o o0 9 0 9 0 0 0004o Q 0 4*

Claims (12)

1. A process for fabricating a solid or hollow composite article of constant cross-section, the article comprising a core and an outer envelope which encircles the said core at least once and strongly adheres to the latter, the process being characterised in that it comprises: layering at least one tape of 1 0 flexible material around a fixed hollow element to form the envelope; continuously feeding the envelope thus formed around the fixed hollow element, up to at least the open end of the said element; and continuously feeding the material which constitutes the core, from a supply which may be in the form of a fluid or a paste, through the fixed hollow element up to the open 1 5 end of the latter, so that when it emerges from the hollow element the said material is received at the outlet of the hollow element in the closed mould formed by the envelope, where it sets, while cooling and adhering to the said envelope.

2. A process according to claim 1, characterised in that the said article is o 00 fed by a thrust or a pull exerted on the envelope in an area situated upstream of the open outlet end of the fixed hollow element.

3. A process according to claims 1 and 2, characterised in that the article is 0"0000 o25 cut into lengths below the open outlet end of the fixed hollow element. "0 0

4. A process according to one of claims 1 to 3, characterised in that the 0044 ooo a tape is applied lengthways in relation to the fixed hollow element and that its longitudinal edges are progressively folded back towards each other until they overlap. S 5. A process according to one of claims 1 to 3, characterised in that the tape is applied obliquely in relation to the axis of the fixed hollow element, so that it can be wrapped helically round the said hollow element.

6. A process according to one of claims 1 to 5, characterised by the use, as the material comprising the core, of an expanded material with open or closed cells, obtained from the interaction of a thermoplastic material with a nucleating agent, for example a gas. :ti AO r-; 27

7. A process according to one of claims 1 to 5, characterised in that the material comprising the core is produced from at least two components, which are mixed inside the fixed hollow element adjacent to its open end, each component being fed into the fixed hollow element in fluid or pasty form from a supply placed upstream of the said fixed hollow element. 1 0 8. An apparatus for manufacturing a composite article of constant cross- section comprising a core and an outer envelope which encircles the said core at least once and adheres strongly to it, the said apparatus comprising means for continuously supplying at least one tape of flexible material, a fixed hollow element for receiving the tape and for forming the envelope from this tape, and 1 5 means for continuously feeding, from a supply, the material which constitutes the core in fluid or pasty form until it comes into contact with the envelope, Ca 2. characterised in that it comprises: means for receiving each tape and layering Sa a it around the fixed hollow element in order thus to form the envelope; meLns Sfor continuously displacing the envelope thus formed around the fixed hollow element, up to at least the open end of the latter; and means for feeding the material which constitutes the core from the supply to the open end of the fixed hollow element, through the said element, and for distributing the said material inside the closed mould which is formed by the envelope, so that it sets, whilst o cooling and adhering to the said envelope.

9. An apparatus according to claim 8, characterised in that it comprises aa", means placed upstream of the open end of the fixed hollow Peement for a-ta pn o ie o moving the composite article. '14-30 10. An apparatus according to claim 9, characterised in that the means for the composite article operate by pulling on the envelope and project S extensively beyond the fixed hollow element on the side of its open end.

11. An apparatus according to claim 9, characterised in that the means for moving the article operate by exerting a thrust on the envelope.

12. An apparatus according to one of claims 8 to 11, characterised in that it comprises means for cutting the composite article into lengths downstream of the open end of the fixed hollow element. M,. T I i.~jj rn~ m 28

13. An apparatus according to one of claims 8 to 12, characterised in that the said means for layering the tape comprise a fixed guide of variable profile, the said guide being suitable for receiving the tape lengthways in relation to the fixed hollow element and for progressively folding back the edges of the tape towards each other until they overlap. 1 0 14. An appar -tus according to one of claims 8 tol2, characterised in that the means for layering and the means for continuously feeding the tape comprise a moving belt or similar, which lays the tape helically on the fixed hollow element and pushes it axially towards the free end of the latter. 00 00 0 00 00 0 0 0 0 0 0 0 0 00 1 5. An apparatus according to one of claims 8 to 14, characterised in that means are provided for applying an adhesive to at least one side of the tape before its final layering around the fixed hollow element. 1 6. An apparatus according to one of claims 8 to 15, characterised in that it comprises, in the end of the fixed hollow element, means for forming at least one internal void in the composite article to be produced.

17. An apparatus according to one of claims 8 to 16, characterised in that it compnises means for distributing, within the fixed hollow element, a mixture of thermoplastic material comprising a nucleating agent, for example a gas, suitable for forming a foam with open or closed cells on expansion. 0 000000 0 025 0 0 0 o Ca 0 0 0 000 C 0000 O 00 00 0 1 8. An apparatus according to one of claims 8 to 16, characterised in that it comprises means for mixing all the components of the material which 3 0 constitutes the core, the said means preferably being provided so that they act together adjacent to the open end of the fixed hollow element. 1 9. An apparatus according to one of claims 8 to 18, characterised in that it comprises means for applying suction to the envelope which operate in 3 5 conjunction with the means for continuously displacing the envelope. 29 A process for manufacturing a solid or hollow composite article of i 5 constant-section, said article comprising a core and an outer cover which extends around at least once said core and firmly adheres to said core, said process being substantially as hereinbefore described with reference to the accompanying drawings. 1 0 21. An apparatus for manufacturing a composite article of constant cross- section comprising a core and an outer envelope which encircles said core at least once and adheres strongly to it, said apparatus being substantially as hereinbefore described with reference to the accompanying drawings.

22. A solid or hollow composite article of constant cross-section having a core and an outer envelope surrounding said core substantially as hereinbefore described with reference to the accompanying drawings. DATED this 9th day of May 1991. GUNTHER S.A. By their Patent Attorneys COLLISON CO. 4. 1~ j A