EP0825951A1

EP0825951A1 - Method and device for compressing and packaging compressible products

Info

Publication number: EP0825951A1
Application number: EP96919880A
Authority: EP
Inventors: Bernard Louis; Bernard Bichot
Original assignee: Saint Gobain Isover SA France
Current assignee: Saint Gobain Isover SA France
Priority date: 1995-05-15
Filing date: 1996-05-09
Publication date: 1998-03-04
Anticipated expiration: 2016-05-09
Also published as: NO975196D0; AR001937A1; CN1184453A; BR9609103A; PL323050A1; NZ308580A; JPH11505200A; HRP960219A2; KR19990014885A; US5979145A; DE69603273D1; NO975196L; AU705317B2; ATE182112T1; HUP9802923A2; DK0825951T3; AU5825496A; EP0825951B1; ES2134624T3; TR199600378A1

Abstract

The invention relates to a method and a device for compressing and packaging automatically compressible materials. The compression is carried out continuously between parallel trays which come closer to each other while they advance. As the trays advance, the materials are accompanied by a lower packaging film and an upper packaging film which are connected on the sides of the units compressed at the end of the compression stage.

Description

METHOD AND DEVICE FOR COMPRESSING AND PACKAGING COMPRESSIBLE PRODUCTS

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

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

US Patent US 4,501,107 describes a machine for stacking mineral wool mattresses and then compressing them to introduce them in the compressed state into a sort of bag which constitutes the packaging of the product. They remain there during transport and storage until they arrive at the site where, by cutting the envelope, the mattresses are released which resume their original thickness.

This document US Pat. No. 4,501,107 provides automatic means for bringing the mattresses into a stack, for compressing the stack, and then for introducing the compressed stack into a bag where it remains in the compressed state. The compression means is a plate placed on top of the stack and driven by a piston of a vertical downward movement, while the plate on which the stack rests remains immobile.

The method described herein is effective but has ^the drawback of any discontinuous method, the dead time separating the end of one start bagging operation for the next operation. Furthermore, the introduction of the compressed pile into the bag cannot be done without using accessories (essentially two plates, below and above the pile) to maintain the pressure during the introduction, accessories which occupy a significant place in the packaging and which therefore allow significant decompression during their evacuation. In addition, the introduction being made in the bags by rear pushing, there is friction of the edges of the compressed stack against fixed sheets and risks damaging the panels. United States patent US 3,717,973 describes a machine for continuously compressing volumes of compressible products, in particular rolls of mineral wool, for introducing them in parallelepiped form, into a sheath of larger dimension where they remain in the compressed state (but less than at the time of their introduction). The device described comprises in the lower part a substantially horizontal belt conveyor and in the upper part, a synchronous conveyor which is in two successive plane parts, the first converging with respect to the lower belt and the second which is substantially parallel thereto. At the exit of this second zone, two new horizontal conveyors convey the product which they have kept compressed in the packaging in the form of a sheath.

Although the compression operation is carried out continuously, packaging at the end of the line is an operation which is discontinuous and requires the intervention of an operator. Furthermore, as in the discontinuous method of US Pat. No. 4,501,107, the maximum compression which 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 removed at the end of the operation.

Document DE-A-26 01 590 describes a method for packaging elongated packages consisting in particular of rolls of fabric. The process is continuous; while the packages placed lengthwise on a conveyor are driven by it, a packaging film is deposited above it, 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 welding device which makes it possible to form a sheath around the package.

Document DE-A-26 01 590 also provides that between two successive packages, a suitable device can weld the packaging sheets and cut them to restore their autonomy to the packages.

The invention sets itself the task of providing a process which makes it possible to effectively compress continuously volumes of compressible products, in particular stacks of mineral wool mattresses. To achieve this objective, the invention provides a packaging method ^"a volume of compressible material in which the volume is placed between two pressing surfaces and laterally moved relative to the pressing direction while the surfaces approach each on the other and in which the surfaces are parallel planes. This arrangement avoids stressing the volume in shear while it is being compressed. The known technique of continuous compression during the transport of the product such as that of US-A-3,717,973 indeed compresses the front of the volume more 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 breakages of fibers, which meant that the product never fully recovered after loosening the compression, its original elasticity.

The technique must also allow rapid action and which does not deteriorate 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 constant speed.

Preferably, the pressing surfaces approach symmetrically with respect to the volume of compressible material.

Unexpectedly, the fact of exerting a symmetrical force on the volume to be compressed makes it possible to work more quickly and to do so by exerting more reduced forces.

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 to keep the compressed product packed the minimum volume it has reached during 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 entrained 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 bonded by welding without changing the plane and, after assembly, the weld is stressed in shear.

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

To implement the method, the invention provides a device comprising two converging conveyors situated one above the other and driven by ^a constant speed, they comprise carriages supporting flat plates parallel to the same plan, which they entail, the plates of a carrier and the other being superimposed. 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 bring one strip into contact with the plate of the first lower carriage and another in contact with that of the first. upper carriage; moreover, the strips of plastic film have a width allowing them to be superimposed on the sides of the volumes of compressed material. Preferably, the converging conveyors comprise, downstream, an area where the difference between corresponding plates is substantially invariable. The device comprises, in particular in this zone, shaping elements intended to place the edges of the superimposed plastic film strips, flat on the sides of the volumes of compressed material as well as, downstream of the shaping elements, means for welding the edges of plastic film strips such as hot air nozzles. Thus, the device makes it possible to block the compressible object at its lowest volume which it can practically keep during its transport and storage. It will not find a possibility of extension until the plastic film sheath is cut on the site. And at this time, thanks to the original compression technique of the invention, it will regain its original volume and, above all, all its elasticity. The description and the figures will make it possible to understand the invention and to perceive the advantages thereof. Among the figures, Figure 1 shows an overall view of a machine according to the invention, Figure 2 shows the upstream end of the machine when switching on a new carriage, Figure 3 shows the downstream end, the exit of a trolley from the circuit and FIG. 4 shows a variant according to which, the trolleys move like the steps of an escalator, FIG. 5 represents 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 packaging it (packing it) without it regaining volume. Upon arrival at the entrance to the machine, the stack is placed on a horizontal plate made of a plate 3. Preferably, the plate is rectangular like the panels and the stack is centered on the plate. It will remain on this plate 3 until it leaves the packaging line. In what follows, we will successively describe the compression operation alone and then the packaging operation.

The plate 3 is supported, like the other nine lower plates and like the 10 upper plates represented, by a carriage 4. In fact, above the stack 1 is another plate 5 identical and parallel to the plate 3 and supported like it by a carriage 6. The two carriages 4, 6 advance synchronously while approaching each other. They are each driven by a chain 7, 8 (or two chains, one on each side of the carriage). The five lower carriages and the five upper carriages which participate in the pressing of the volume 1 constitute a train which advances regularly, driven by the 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 makes it possible to guide the chain. At the rear of the carriage, on each side are provided guide means in the form of rollers 9, 10 which follow a guide 11, 12 (a rail). The paths followed by the chains 7, 8 and by the guides 11, 12 are such that 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 there is no slippage between the plates and the material they compress. In the figure, a straight path has been shown for the chains 7, 8 as for the rear rollers of the carriages 9, 10 but it may be advantageous to have a different slope depending on the phases of the compression process.

At the end of compression (which in the figure shows two carriages at the bottom and two at the top) the compressed material is transported without change in volume. At the end of the packaging line, the carriages are extracted from the path that they followed during the compression and go in ^the opposite direction, driven by chains and guided by a second guide portion 13 below the guides 11 and 14 above the 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 part 13 and the upper guide part 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 (FIG. 2a), it is in position to the right, but when the carriage starts again (figure 2b), it is located in stop on the left. It will move again to the right during the progression of the carriage so that, when the roller 15 arrives in the connection area 18, the movable guide 17 is in place there 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. It is however preferable to have a “positive” drive of the movable guide element 17 by the toothed wheel 19 which drives and / or supports the chain 7. This mechanical connection is produced by a connecting rod-crank system not shown.

In FIG. 3, the system is different because the movable guide element 20 moves, 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 supporting (and possibly driving) 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 shown in Figures 2 and 3 save space but it would also be possible to have a continuous rail which is followed by the rollers 9, 10, 15, 21. In this case, however, devices are plan to avoid, in the left part at the bottom or in the right part 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 for example be a chain which drives the rollers 15, 21 similar to chains 7, 8.

FIG. 4 represents a variant of the drive system of the trays which have 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 here applied to a volume of compressed material but is also applicable to products whose density does not decrease during their packaging. In the case of the compressible-compressed products of the invention, the packaging technique described below or an equivalent technique is an essential complement to the compression method because it alone makes it possible to practically conserve the compressed volume while limiting recovery as much as possible. volume.

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 of the perimeter of the compressed volume increased by a few centimeters to allow recovery of the films each constituting half of the sheath which packages and traps the compressed product. .

The choice of two identical half-sheaths is arbitrary. It makes it possible to make the junction of the two films in the middle of the sides of the compressed volumes, but we could as well have chosen different widths or asymmetrical positions for the packaging films 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 conducted along the support plate 30 (located at a defined distance from the support plate 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 joining. To carry out this, several means 33 are possible, addition of an external adhesive (hot melt in particular), deposition of a double-sided adhesive that has been introduced at the upstream end of the support plate 30 of the film. lower, 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 polyethylene film (high density) with a thickness of 50 to 100 μm (tests made with a low density BD film have also given excellent results), the means for achieving 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. A person skilled in the art adapts the air temperature and blowing speed to the speed of movement of the film in front of the nozzles. In addition, safety devices cut off the hot air supply (or become so) in the event of a line shutdown.

The packaging technique which has just been described in detail uses a technique of autogenous welding of a plastic film; it would not be departing from the scope of the invention to use a packaging film of another kind or a technique for joining the edges of the different film. Likewise, the means of assembling the edges of the two upper and lower strips which intersect and overlap over a large area could be replaced by an edge-to-edge junction, where the internal face of a film is in contact with the face. internal of the other. This technique is not preferred because it solicits the weld or the glued junction in peeling, and this type of assembly is less solid than that which was retained where the joint is stressed in shearing.

The use of a resistant and high modulus film, that is to say that it does not stretch very much under load, makes it possible to keep a volume of compressed materials such as a stack of mineral fiber mattresses the minimum possible size which deviates little from the size it has reached at the end of compression, the effect of the release from the plates 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 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 conveyor 37. They are associated in a chain in the packaging sheath. Between two packages, the sheath is presented as an empty hose 38. In a variant of the invention, provision has been made to install at this level a known device which makes it possible to automatically weld and / or cut the films to give the packages of packaged materials their autonomy and possibly protect them if the packaging is closed. The tests carried out with the machine which has just been described for compressing and conditioning mineral wool mattresses have been 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. 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, has been placed so that, at the end of the line, the silk trays, 125 mm apart. We made a measurement of the force exerted, it was 206 decanewtons.

The packaging film was HD polyethylene 60 μm thick, the line advancing speed was 20 m / min. At the end of the compression-packaging-transverse welding-separation of the packages cycle, the volume of the packages was measured. It was 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 160 169 166 200 (mm)

Maximum compression 4.6 / 1 5.6 / 1 6.9 / 1 7.5 / 1

Overall thickness of 318 320 325 350 packaged package (mm)

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 regained their nominal thickness, 100 mm.

The compression and packaging method of the previous tests thus makes it possible to have a packaged product whose compression ratio is the maximum that 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 condition and easily package volumes of compressible materials and in particular stacks or rolls of mineral wool. Unlike the previous processes, the packaging is done continuously and the compression which takes place simultaneously and symmetrically over the volume avoids degradation due to the shearing of the material and makes it possible to operate faster with less effort.

Claims

1. A method of packaging 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, characterized in that the surfaces are parallel planes.

2. Method according to claim 1 characterized in that the pressing surfaces are those of plates carried by carriages associated two by two.

3. Method according to claim 2 characterized in that each of the carriages is associated with a carriage which precedes it and another which follows it, to form two trains driven at a constant speed.

4. Method according to claim 1 characterized in that the pressing surfaces approach symmetrically with respect to the volume of compressible material.

5. Method according to one of the preceding claims characterized in that, at the end of pressing, the volume of compressed material is wrapped in a sheath which limits its expansion.

6. A method of continuously packaging a volume of material in which the packaging film is entrained at the same time as the product to be packaged and then its bound edges, characterized in that the packaging film consists of two strips placed above and below the volume of material, in that their width allows them to overlap on the sides of the volume and in that they are linked to each other on said sides of the volume.

7. Method according to claim 6 characterized in that the packaging film is a plastic film, in that the strips are bonded by welding without changing the plane and in that, after assembly, the weld is stressed in shear.

8. Method according to claim 5 and according to one of claims 6 or 7 characterized in that the sheath which limits the expansion of the compressed volume consists of two strips of packaging film linked.

9. Method according to one of the preceding claims characterized in that the volume of compressible material consists of panels of mineral wool, in particular glass wool, superimposed.

10. Device for compressing and packaging a volume of compressible material having two converging conveyors situated one above the other and driven by ^a constant speed characterized in that it comprises carriages supporting plates planes, parallel to the same plane, which they drive, the plates of one conveyor and of the other being superimposed.

11. Device according to claim 10 characterized in that the corresponding flat plates on a conveyor and on the other are symmetrical with respect to a plane which is parallel to them.

12. Device according to claim 10 or claim 11 characterized in that it comprises, associated with each conveyor, a distributor of a strip of plastic film arranged so as to bring a strip into contact with the plate of the first lower carriage and another in contact with that of the first upper carriage and in that the strips of plastic film have a width allowing them to be superimposed on the sides of the volumes of compressed material.

13. Device according to one of claims 10 to 12 characterized in that the converging conveyors comprise, downstream, an area where the difference between corresponding plates is substantially invariable.

14. Device according to claim 13 characterized in that it comprises, in particular in the area where the difference between plates is substantially invariable, shaping elements intended to place the edges of the superimposed strips of plastic film, flat on the sides of the volumes of compressed material.

15. Device according to claim 14 characterized in that, downstream of the shaping elements, means have been placed for welding the edges of the strips of plastic film such as hot air torches.

16. Device according to claim 15 characterized in that, at the outlet of the conveyors, means are installed for welding and / or cutting the plastic films between successive volumes of compressed material.

17. Device according to one of claims 10 to 16 characterized in that, on each conveyor, the carriages are linked to a chain which pulls them during compression and packaging and which pushes them during their return and in that they comprise at the other end a guiding means, such as a roller, running on a guide such as ^a rail and in that the guide comprises two parts, one for the outward and the other for the return.

18. Device according to claim 17 characterized in that at the ends of the carriers, elements of the guide are movable to allow the passage of the carriages from one part of the guide to the other.