EP0825951B1 - Method and device for compressing and packaging compressible products - Google Patents

Description

The invention relates to techniques for compressing and packaging materials compressible such as in particular sets of mineral fiber panels.

To transport and store bulky products at low cost but compressible and likely to regain their volume and all their characteristics of origin after their release, it is necessary to have suitable techniques and machines. They must allow effective compression to be obtained quickly and automatically quality packaging while preserving the characteristics of the products concerned.

US Patent US 4,501,107 describes a machine for stacking mineral wool mattress and then compress them to introduce them in a compressed state into a kind of bag which constitutes the packaging of the product. They stay there during transport and storage until they arrive at the site where by cutting the envelope, we release the mattresses that return to their original thickness.

This document US Pat. No. 4,501,107 provides automatic means for stacking the mattress, to compress the pile, then to introduce the compressed pile into a bag where it stays in a compressed state. The compression means is a plate placed on top of the stack and animated by a piston of a vertical downward movement, while the plate on which the battery rests, it remains immobile.

The method described in this document is effective but it has the disadvantage of any discontinuous method, that of the dead times which separate the end of an operation bagging at the start of the next operation. Furthermore, the introduction of the battery compressed in the bag can not be done without using accessories (essentially two plates, below and above the stack) to maintain pressure during the introduction, accessories which occupy a significant place in the packaging and which therefore allow significant decompression during their evacuation. Moreover, the introduction being made in the bags by back pushing, there is friction of the edges of the stack compressed against fixed sheets and may damage the panels.

US Patent 2,960,023 relates to the compression and packaging of sheets of crepe paper. The compression member consists of two caterpillars made of hinged plates which come together making between they angle and finish compression by being parallel to each other the other.

US Patent US 3,717,973 describes a machine to continuously compress volumes of compressible products, particular rolls of mineral wool, to introduce them in the form parallelepiped, in a sheath of higher dimension where they remain in the compressed state (but less than at the time of their introduction). The device described comprises at the bottom a conveyor belt substantially horizontal and in the upper part, a conveyor synchronous which is in two successive plane parts, the first converging with respect to the lower mat and the second which is there substantially parallel. At the exit of this second zone, two new horizontal conveyors convey the product they have kept compressed in the sheath-shaped packaging.

Although the compression operation is carried out continuously, packaging at the end of the line is an operation which is discontinuous and requires operator intervention. Furthermore, as in the discontinuous method of US 4,501,107, the maximum compression which has was obtained at the end of the compression operation is not kept in the packaging because here too treadmills which have entered the sheath must be extracted at the end of the operation.

Patent application FR 2 546 478 relates to methods of compression and packaging of rolls of toilet paper. In this document, two wrapping films, one above the other below of the product to be packaged are sealed to each other, especially in the space separating two products.

Document DE-A-26 01 590 describes a method for packaging elongated packages made up in particular of rolls of fabric. The process is continuous; while bundles placed lengthwise on a carrier are driven by him, we place a film above the width of which is such that it alone can surround the package. The carrier is in two parts, each supporting one side of the package. Between the two parts, below, is installed a device for solder which allows to form a sheath around the package.

Document DE-A-26 01 590 also provides that between two successive bundles, a suitable device can weld the sheets packaging and cut them to make the packages independent. The invention sets itself the task of providing a method which makes it possible to effectively compressing product volumes continuously compressible, in particular stacks of mineral wool mattresses.

To achieve this objective, the invention proposes a method of conditioning of a volume of compressible material in which the volume is placed between two pressing surfaces and transported laterally with respect to the pressing direction while the surfaces approach each other and in which the surfaces are planes parallel.

This arrangement avoids stressing the volume in shear during that it is compressed. The known technique of continuous compression during transport of the product such as that of US-A-3,717,973 indeed compresses the front more volume than the rear, which causes a shearing force detrimental to the product. In the case of mineral wool mattresses in particular, this technique resulted in fiber breaks, which meant that the product never fully recovered after loosening of compression, its original elasticity.

The technique must also allow rapid action which does not damage the elastic properties of the material.

The invention proposes that the pressing surfaces be those of plates carried by carriages associated two by two and that each of the carriages is associated with a carriage which precedes it and another which follows it, to constitute two trains animated by a speed constant.

Preferably, the pressing surfaces are brought together symmetrically by relative to the volume of compressible material.

Unexpectedly, the fact of exerting a symmetrical force on the volume to compressing makes it possible to work faster and to do it by exerting more efforts reduced.

Of course, at the end of pressing, the volume of compressed material is wrapped in a sheath which limits its expansion, but, as it is also a mission of the invention of keeping the packaged compressed product the minimum volume it has reached during of its compression, the method of the invention provides that the sheath consists of two strips of packaging film placed above and below the volume of material, that they are dragged with it, that their width allows them to overlap on the sides of the compressed volume and that they are linked to each other on said sides of the volume. Preferably, the packaging film is a plastic film, the strips are linked by welding without changing plan and, after assembly, the welding is requested in shear.

This technique of forming the sheath in situ, directly on the volumes of materials, at the time when the compression is maximum guarantees that the volume will not change not on the packed product.

To implement the method, the invention provides a device comprising two converging conveyors located one above the other and driven at a speed constant, they include carriages supporting flat plates, parallel to the same plan, which they entrain, the plates of a carrier and the other being superimposed. Of preferably, the corresponding flat plates on one conveyor and on the other are symmetrical with respect to a plane which is parallel to them.

To constitute the sheath, the device of the invention comprises associated with each conveyor a distributor of a strip of plastic film arranged so as to put a strip in contact with the plate of the first lower carriage and another in contact with that of the first upper carriage; in addition, the plastic film strips have a width allowing them to overlap the sides of the volumes of compressed material. Of preferably, the converging carriers have, downstream, an area where the difference between corresponding plates is substantially invariable. The device includes, in particular in this zone, conforming elements intended to place the edges of the film strips plastic superimposed, flat on the sides of the volumes of compressed material as well as downstream of the shaping elements, means for carrying out the welding of the edges of the strips plastic film such as hot air nozzles.

Thus, the device makes it possible to block the compressible object at its lowest volume. that it can practically keep during its transport and its storage. He will not find a possibility of extension only when the sheath is cut in plastic film, on site. And at this time, thanks to the original compression technique of the invention, it will find its starting volume and, above all, all its elasticity.

la figure 1 montre une vue globale d'une machine selon l'invention,

la figure 2 représente l'extrémité amont de la machine lors de la mise en circuit d'un nouveau chariot,

la figure 3 montre à l'extrémité aval, la sortie d'un chariot du circuit et

la figure 4 montre une variante selon laquelle, les chariots se déplacent comme les marches d'un escalier roulant,

la figure 5 représente les conformateurs des bords des bandes de film d'emballage et une buse à air chaud.

The description and the figures will make it possible to understand the invention and to perceive the advantages thereof. Among the figures,

FIG. 1 shows an overall view of a machine according to the invention,

FIG. 2 represents the upstream end of the machine when a new carriage is switched on,

FIG. 3 shows at the downstream end, the exit of a carriage from the circuit and

FIG. 4 shows a variant according to which the trolleys move like the steps of an escalator,

FIG. 5 shows the shapers of the edges of the strips of packaging film and a hot air nozzle.

FIG. 1 represents a line for packaging volumes of a compressible material, in this case a stack 1 of panels 2 of mineral fibers 8 in number here. It is a matter of compressing this stack and conditioning it (packing) without it regaining volume.

On arrival at the entrance to the machine, the stack is placed on a horizontal tray made of a plate 3. Preferably, the plate is rectangular like the panels and the stack is centered on the plate. She will stay on this plate 3 until she leaves the line conditioning.

In what follows, we will successively describe the compression operation alone and then the packing operation.

Plate 3 is supported, like the other nine lower plates and like the 10 upper plates represented by a carriage 4. Indeed, above the stack 1 is finds another plate 5 identical and parallel to plate 3 and supported like it by a carriage 6. The two carriages 4, 6 advance synchronously, approaching one the other. They are each driven by a chain 7, 8 (or two chains, one of each side of the carriage). The five lower carriages and the five upper carriages that participate when pressing volume 1 constitute a train which advances regularly, driven by chains 7, 8.

During the compression operation, the carriages 4, 6 are pulled by the chains 7, 8 to which they are linked by axes each passing through the hollow of a link in the chain while a smooth roller centered on the axis can guide the chain. At the back of the cart, on each side are provided with guide means in the form of rollers 9, 10 which follow a guide 11, 12 (a rail). The paths followed by chains 7, 8 and by guides 11, 12 are such as during the progression of the carriages 4, 6, the plates 3, 5 remain substantially horizontal while progressing towards each other. It could happen, however, that for one reason or another the plates 3, 5 are inclined relative to the horizontal. The important thing is that they are always as parallel as possible and that it does not happen no sliding between the plates and the material they compress.

In the figure, there is shown a straight path for the chains 7, 8 as for the rear rollers of the carriages 9, 10 but it may be advantageous to have a slope different depending on the phases of the compression process.

At the end of compression (which concerns in the figure two carriages at the bottom and two above) the compressed material is transported without any change in volume.

At the end of the packaging line, the carriages are extracted from the trajectory that they followed during the compression and go back the other way, pushed by the chains and guided by a second guide part 13 below the guides 11 and 14 above of guide 12.

To pass from one part of guide 11, 12 to another 13, 14, it is necessary to operate switches. Figure 2 shows the upstream switch and Figure 3 the downstream switch (in these cases, it is the lower carriage, the devices for the upper carriages are equivalent).

In FIG. 2a , the roller 15 must leave the lower guide part 13 to join the upper guide part 11 before starting the compression operation. At the other end of the carriage, the axis 16 linked to the carriage is driven by the link of the chain 7 which it crosses.

Between the lower guide portion 13 and the upper guide portion 11 is a movable guide element 17. It is capable of sliding laterally in the extension of the upper guide part 11. When the carriage arrives (Figure 2a), it is in position to the right, but when the carriage leaves (Figure 2b), it is located in the stop on the left. he goes move again to the right while the carriage is progressing so that, when the roller 15 arrives in the connection zone 18, the movable guide 17 is there place to avoid any discontinuity.

The moving guide 17 can be moved by a jack controlled by a central computer responsible for controlling the entire packaging line. he is however preferable to have a 〈positive〉〉 drive of the movable guide element 17 by the tooth wheel 19 which drives and / or supports the chain 7. This mechanical connection is carried out by a rod-crank system not shown.

In FIG. 3 , the system is different because the movable guide element 20 moves by driving with it the roller 21 which thus passes almost instantaneously from the upper guide part 11 to the lower guide part (back) 13. The transfer takes place while the toothed wheel 22 support (and possibly drive) of the chain 7 makes a U-turn. The connecting rod 23, in the retracted position in Figure 3a acts during the rotation of the toothed wheel 22 on the element 20 which rotates around its axis 24 and comes to put (Figure 3b) the movable guide element 20 vis-à-vis screw of the lower guide portion 13 when the connecting rod 23 is extended.

The two systems represented in FIGS. 2 and 3 make it possible to gain place but it would also be possible to have a continuous rail which is followed by the rollers 9, 10, 15, 21. In this case, devices are however to be provided to avoid, in part left at the bottom or part right at the top, that the carriage, driven by its weight at the end of race, don't leave in the direction it comes from. It can be for example a chain which drives the rollers 15, 21 similar to chains 7, 8.

Figure 4 shows a variant of the tray drive system which has the function of transporting and pressing the volumes of compressible materials. This traditional system, the mechanism of which is similar to that of escalators, has the disadvantage of requiring much more space for the return circuit. Furthermore, when the plates must move apart to release the compressed products, they cannot remain parallel or horizontal, which does not facilitate handling of the finished products. Mixed solutions are also possible, one side of the stacks of panels being supported (or surmounted) by a plate associated with a carriage while the other is supported on a single synchronous conveyor belt so as to avoid slipping. But in this case, the packaging process could not be that described below, it must be adapted.

The method of the invention also includes an original packaging technique. It is applied here to a volume of compressed material but is also applicable to products whose density does not decrease during their packaging. In the compressible products - tablets of the invention, the packaging technique described below or an equivalent technique is an essential complement to the compression method because it alone allows practically to keep the volume compressed while limiting volume recovery as much as possible.

In FIG. 1 and in FIG. 4 is shown a system for supplying packaging film 25. The film comes from two rollers, not shown. It has a precise width which during the tests was for each of the films 25 equal to half the perimeter of the compressed volume increased by a few centimeters to allow recovery of the films constituting each, half of the sheath which packages and traps the compressed product. .

The choice of two identical half-sheaths is arbitrary. It allows to do the junction of the two films in the middle of the sides of the compressed volumes but we could have as well choose different widths or asymmetrical positions for the films packaging and therefore, junction locations placed differently.

The films 25 are guided by rollers 26 so as to come into contact respectively with the plates 3, 5 of the first carriages 4, 6. On the lower plate 3, the packaging film projects laterally over the products to be compressed (and, even possibly from the tray 3 itself). In the upper part, the edges of the strip fold down on each side of the stack 1. The film 25 is preferably driven only by the movement of the carriages, which ensures that the film stretches longitudinally under and on the stack 1 of mattress 2 of mineral fibers. In Figure 1 , the last carriages are in the compression zone, the first two in the packaging zone, where the length of film between plates no longer varies, and the fifth, in the middle, at the transition between the two zones.

From the start of the packaging area, Figure 5 , we placed in the middle area, on each side, conformers whose role is to set up the edges of the film strips 25. We see in the figure a plate support 27 on which the upper film comes to rest (outside) and which extends until after the junction zone. A conformator 28, a sort of metal plate of suitable shape, bends the edge of the upper film 34 which a pressure roller 29 comes to apply on the support plate 27.

Symmetrically, the edge of the lower film 35 is taken by the shaper 31 and run along the support plate 30 (located at a defined distance from the plate support 27) where it is pressed by the roller 32. At the end of the plate 30, the two edges, upper and lower, come into contact and one can realize their solidarity. To perform this, several means 33 are possible, providing a exterior glue (hot melt in particular), deposit of a double-sided adhesive that has been introduced at the upstream end of the support plate 30 of the lower film, or else autogenous welding of suitable plastic films. It is this technique which constitutes the preferred embodiment. of the invention. The film is a HD (high density) polyethylene film with a thickness of 50 to 100 µm (tests made with a low density BD film also gave excellent results), the means to achieve the fusion of the material is the heat provided by nozzles which blow air at a temperature between 400 and 650 ° C; the tests were carried out with air heaters from the LEISTER Company. The skilled person adapts air temperature and blowing speed to the speed of movement of the film in front the nozzles. In addition, safety devices cut off the hot air supply (or deflect it) in the event line stop.

The packaging technique which has just been described in detail uses a autogenous welding of a plastic film; we would not go beyond the scope of the invention in using a wrapping film of another kind or a technique of joining the edges of the different movie.

Similarly, the means of assembling the edges of the two upper bands and that intersect and overlap over a large area could be replaced by an edge-to-edge junction, where the internal face of a film would be in contact with the inner side of the other. This technique is not preferred because it solicits welding or the bonded junction in peel, and this type of assembly is less solid than that which was retained where the joint is stressed in shear.

The use of a resistant and high modulus film, that is to say that it only elongates very little under load allows to keep at a volume of compressed materials as a stack of mineral fiber mattresses the minimum size possible which deviates little from the size that it has reached at the end of compression, the effect of the release from the platens such as 3, 5 being simply a deformation of the perimeter of the sheath which is substantially rounded by increasing its thickness in the axis and by thinning on the edges while its surface and therefore the volume of the compressed product increases slightly.

At the exit of the line, the packets of packaged materials 36 are driven by a carrier 37. They are associated in a chain in the packaging sheath. Between two bundles, the sheath is presented as an empty hose 38. In a variant of the invention, we have planned to install at this level a known device which allows to weld and / or cut films automatically to give packets of wrapped materials their autonomy and possibly protect them if the packaging is closed.

The tests carried out with the machine which has just been described to compress and conditioning mineral wool mattresses were very positive.

We made a series of stacks of 8 glass wool mattresses with a dimension of 1200 x 600 mm, the thickness of the mattresses was 128 mm and their density 7 kg / m ³ . A stack height before compression of 1010 mm was measured (slight compression under the effect of weight). Identical stacks followed each other normally on the line.

The upper part of the machine which can be moved vertically having been placed so that at the end of the line, the plates are 125 mm apart. We have made a measurement of the force exerted, it was 206 decanewtons.

The packaging film was 60 µm thick polyethylene HD, the speed line advancement was 20 m / min. At the end of the compression-packaging-welding cycle transverse - separation of the packets, the volume of the packets was measured. He was from 112.5 liters, which corresponds to a compression ratio of around 6.5. When release of its envelope, the stack of products found a height of 950 mm, which corresponds to a loss of thickness per panel, acceptable.

A second series of tests was carried out. This involved compressing and packaging glass wool panels with a dimension of 1350 x 600 mm with a nominal thickness of 100 mm (108 mm of actual thickness). Their density was 13.75 Kg / m ³ .

Stacks of 7, 9, 11 and 15 panels were successively produced and each stack was compressed more than the previous one. The table below presents the results. Number of panels 7 9 11 15 Stack thickness (mm) 740 945 1145 1545 Final distance between plates (mm) 160 169 166 200 Maximum compression 4.6 / 1 5.6 / 1 6.9 / 1 7.5 / 1 Overall thickness of the packaged package (mm) 318 320 325 350 Compression ratio 3.1 / 1 3.9 / 1 4.7 / 1 5.6 / 1

At the end of the operation, after tearing of the sheath, the released panels were found their nominal thickness, 100 mm.

The compression and conditioning method of the previous tests allows thus having a packaged product whose compression ratio is the maximum it it is possible to keep with a deformable sheath as packaging.

The techniques of the invention which have just been described thus make it possible to easily pack and pack volumes of compressible materials and including piles or rolls of mineral wool. Unlike the processes packaging is done continuously and compression takes place simultaneously and symmetrically on the volume avoids damage due to shearing of the material and allows you to operate faster with less effort.

Claims (17)

1. Method of packaging at least one mass of compressible material, in which each mass is placed between two pressing surfaces arranged facing one another and is transported therewith, sideways relative to the direction of pressing, whilst the pressing surfaces move towards one another, the two pressing surfaces advancing at the same speed in the direction of transportation, characterized in that the surfaces are parallel in pairs as soon as the compression starts and remain parallel constantly during their movement towards one another, and in that the direction of pressing remains parallel to itself during the transportation.
2. Method according to Claim 1, characterized in that the pressing surfaces are those of plates carried by carriages associated in pairs.
3. Method according to Claim 2, characterized in that each of the carriages is associated with a carriage which precedes it and with another which follows it to constitute two trains moved with a synchronous movement, particularly at a constant speed.
4. Method according to Claim 1, characterized in that the pressing surfaces move towards one another symmetrically with respect to the mass of compressible material.
5. Method of packaging masses of compressible material, characterized in that it comprises a compression step according to any one of the preceding claims, after which, upon completion of the pressing, the mass of compressed material is enveloped in a sheath which limits its expansion.
6. Method according to Claim 5, characterized in that the sheath is formed from packaging films which are moved at the same time as the product to be packaged and which are arranged in two strips placed above and below the mass of material between the mass and the transporting surfaces, in that the width of the strips allows them to overlap on the sides of the mass, in the direction of transportation, and in that they are connected to one another continuously on the said sides of the mass.
7. Method according to Claim 6, characterized in that the packaging film is a plastics film, in that the strips are connected by welding without change in plane, and in that after assembly, the welding is subject to shear stress.
8. Method according to any one of the preceding claims, characterized in that the mass of compressible material is constituted by superimposed mineral-wool, particularly glass- wool batts.
9. Device for compressing and packaging a mass (1) of compressible material, comprising two converging conveyors situated one above the other, comprising a compression region and a packaging region, and moved with a synchronous movement, particularly at a constant speed, and each comprising at least one flat plate (3; 5), these plates being arranged facing one another in the compression and packaging regions, characterized in that it comprises carriages (4; 6) supporting the said flat plates which they move, and means (11, 12, 13, 14) for moving the said flat plates towards one another in the compression region and for keeping the said plates parallel to the same plane throughout the compression region and preferably as far as the output of the packaging region.
10. Device according to Claim 9, characterized in that all of the corresponding flat plates on one conveyor (3) and on the other (5) are symmetrical with respect to the same plane which is parallel to the plates.
11. Device according to Claim 9 or Claim 10, characterized in that it comprises, associated with each conveyor, a distributor (26) of a strip of plastics film (25) arranged in a manner such as to put one strip (35) in contact with the plate (3) of the first lower carriage (4) and another in contact with that (5) of the first upper carriage (6), and in that the strips of plastics film (25) have a width which allows them to overlap on the sides of the masses (1) of compressed material.
12. Device according to any one of Claims 9 to 11, characterized in that the converging conveyors comprise, downstream of the compression region, a region in which the distance between corresponding plates is substantially constant.
13. Device according to Claim 12, characterized in that it comprises, particularly in the region in which the distance between plates is substantially constant, shaping elements (28, 31) for placing the edges of the superimposed strips of plastics film (34, 35) flat on the sides of the masses of compressed material.
14. Device according to Claim 13, characterized in that means such as hot-air blowpipes (33) are disposed downstream of the shaping elements (28, 31) for welding the edges of the strips (34, 35) of plastics film.
15. Device according to Claim 14, characterized in that means are installed at the output of the conveyors for welding and/or cutting the plastics films (25) between successive masses (1) of compressed material.
16. Device according to any one of Claims 9 to 15, characterized in that, on each conveyor, the carriages (4, 6) are connected, at one end, to a chain (7, 8) which pulls them along the compression and packaging region and which pushes them during their return, in that they comprise, at the other end, a guide means such as a roller (9, 10) rotating on a guide (11, 12, 13, 14) such as a rail, and in that this guide comprises two portions, one (11, 12) for the outward travel and the other (13, 14) for the return travel.
17. Device according to Claim 16, characterized in that guide elements (17; 20) at the ends of the conveyors are movable to allow the carriages to move from one guide portion (11, 12) to the other (13, 14).

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