ITMI990225A1 - PROCEDURE FOR THE MANUFACTURE OF FOLDABLE FIBER PANELS - Google Patents

Description

connection (8a, 8b) on each of the two parts of the fiber panel (2a, 2b), as well as application and possibly hardening of the connection element (16).

(Figure 5)

Description of the finding

The invention relates to a process for manufacturing foldable fiber panels or cardboard, which have at least one visible side. All the panels produced by the use of wood-cellulosic fibers, for example hard fiber panels or medium density fiber panels (MDF), belong to fiber panels, sheets or cardboard. Such panels are used, by way of example, as rear walls of cabinets.

The rear walls of cabinets were formed for a long time from single sheets or panels of fibers, which were connected together, and fixed, by means of separate connecting elements. In order to minimize the manipulation of individual parts, however, solutions have been sought for some time to manufacture separable rear walls for cabinets, which can be assembled without auxiliary means.

Known processes for the continuous manufacture of parts of panels or plates connected to each other are described, by way of example, in German patents no. 838 361 (Dichmann) and 4418 274 (BHF). The fact that they can be inserted in continuous manufacturing processes is common to the two processes. This is an absolutely necessary prerequisite to be able to offer these mass products at minimal prices, without unnecessary manipulations.

In the German patent DE-C 838 361 it is proposed to first provide grooves on a panel, from which the parts of the fiber panel to be connected to each other must be produced, where the grooves are then covered by a connecting element. Finally, the bottom of the groove is then milled away from the other side and the individual panel parts, to be connected together, are arranged on the connecting element. This process is not suitable for the manufacture of rear walls of furniture, as it cannot be used for sheets, or panels, with at least one visible side, since both surfaces of the panel are machined in the execution of this process.

In the German patent DE-C 44 18 274 a process is described which is suitable for the manufacture of folding rear walls for furniture, therefore for panels or fiber sheets with at least one visible side. Also in this process, which uses the processing steps of the German patent DE-C 838 361, a groove is first milled, then the connecting element is applied, and finally, by processing the visible side, the bottom of the groove. The panel parts connected by the connecting element are then folded, so that the visible sides face each other. This procedure is very expensive in its execution. Processing the fiberboard or fiberboard on the visible side without damaging the groove with the connecting element is barely possible, without damage to the visible side of the fiberboard or the connecting element. The bending of the fiberboard parts after the attachment of the connecting element and the milling of the second groove already frequently leads to damage on the connecting element.

Therefore, the object of the invention is to propose a simple and economical process for the continuous manufacture of foldable fiber panels.

This task is solved by means of a process with the characteristics of claim 1. The starting product for the manufacture of cartons or foldable fiber panels is a coated fiber panel, or laminated, at least on one side, or equipped with an ennobling on the other. way, manufactured by a continuous process. The side coated, for example, with paint or decorative paper, is referred to in the following as the visible side. The second side - generally not coated - of the fiber panel is referred to in the following as the canvas side.

The starting fiber board, from which the sheet or pliable fiber board is to be produced, is first divided, by means of a separation cut, into at least two fiber board parts. The cut can take place both from the visible side and also from the canvas side. The two parts of the fiber panel are then placed one on top of the other with the aid of corresponding overturning devices, for example with the aid of a rotation or overturning star, or by means of a lever arrangement. In connection therewith, the visible sides of the fiberboard parts are turned towards each other.

This step of the complete separation of the single starting fiberboard and the subsequent rotation of the fiberboard parts is new and extremely unusual in correlation with the further processing of fiberboards or sheets to form furniture parts. The principles followed up to now have always avoided such a phase, because the overturning, that is rotation, and the orientation of the panel parts appear to the person skilled in the art as a complicated, expensive and space-requiring intermediate phase. Up to now, it has always been preferred to allow the further processing to be carried out as far as possible in a plane in a non-interrupted manner in continuous or interconnected transport systems, and to bend the panel parts only after the connection element has been applied. Any interruption of the continuous transport, or even the manipulation of panel parts, were considered as a device that reduced the performance of the production plant.

In the course of tests, however, it proved to be a great advantage to carry out the continuous manufacture of foldable fiber sheets or panels in the sequence of steps of claim 1. A separation cut, with which the starting fiber panel is completely divided into two parts of fiberboard, it can be made with an easy-to-set saw. There is no need for the time-consuming setting of a precise depth of cut, as is the case when making a groove. If the cut takes place from the visible side, then damage to the visible side at the cutting edge is largely avoided, because the saw protrudes on the canvas side of the fiberboard and, consequently, any cracks are found in the area of the edge, coming to originate through the cut, on the canvas side. A particular advantage of this process is also that straight edges are produced, which do not require any further processing. These edges, hereinafter referred to as external edges, after overturning are at the stop. The edges lying on the outside in the starting fiber board or slab, hereinafter referred to as connecting edges, according to the method according to the invention, can now be processed in such a way that not only the connecting element can be applied, but also such that the finished panel parts accurately present the pre-assigned dimensions.

The rotation or overturning of the panel parts can take place with very simple auxiliary means, the panel parts are freely movable and easy to manipulate. Contrary to this, the folding of the panels according to the procedure described in DE-C 44 18 274, must be performed with great care, therefore with machines to be set with corresponding precision, to ensure that the panels are not moved reciprocally, so that the connecting element.

The fiberboard parts are then oriented flush, so that they can be connected together along a connecting edge. The orientation of the panel parts takes place with the aid of simple stops, on which at least two panel parts are oriented by means of transport devices. As already explained, the panel parts are oriented on the stops with the outer edges originating by the separation cut. The edges lying on the outside in the starting panel plate, the connecting edges, are accessible to further processing devices by this orientation. The parts of the fiberboard oriented flush are then fixed removably, so that they remain mutually in a defined position for the subsequent processing steps. It is preferred to secure the fiberboard parts, after orientation, by means of a locking device, i.e. tightening. Suitable locking devices are, by way of example, pairs of spring-loaded rollers, which exert pressure on the fiber panel parts superimposed on each other.

The fiberboard parts are then processed along the connecting edge. In the simplest case, the connecting edge is beveled from the fabric side towards the visible side, to create a good bonding surface for the connecting element. However, it is also possible to profile the connecting edge, for example when the connecting element must close flush with the plane of the visible surface. In this way of proceeding it is advantageous that these processing steps can be constantly monitored optically, and the fact that adjustments and changes in the setting can be carried out in a simple way, because the necessary processing devices are arranged laterally, and therefore in an easily accessible way. In the prior art methods described above, the fiber plate or panel is processed transversely to the transport direction over the entire width of the transport path, respectively in the center of the transport path and cutters and application devices for adhesive are required. and similar, both on the side of the visible surface, and also on the side of the surface or canvas side. In the method according to the invention, on the other hand, all the processing devices are arranged laterally to the transport path, since only the connecting edges of the fiberboard parts have to be processed, since the outer edges are already completely processed . A particular preference of the method according to the invention is seen in the fact that, by the respective subsequent processing of parallel edges of single fiber panel parts, associated with each other, the pre-assigned dimensions and angles can be particularly maintained. precise and with minimal effort.

If necessary, the connecting edge is prepared again after processing for the application of the connecting element, for example by applying a seal or an adhesive component.

Finally, the connecting element is applied. In the simplest case, an adhesive, preferably a polyurethane-based synthetic adhesive, is applied as a connecting element. Such adhesives are offered as melt adhesives, for example a PUR adhesive with a viscosity of 22,500 ± 7,500 mPas at 120 ° C and with a processing temperature of 120 ° C up to 140 ° C. However, it is also certainly possible that a tape, possibly fitted with an adhesive, is used as the connecting element, for example a fabric tape or a foil tape.

Depending on which adhesive is used, the fiberboard parts are now still bonded for so long until the adhesive hardens. If necessary, the panel parts or fiber sheets pass through, at least in the area of the connecting edge equipped with the connecting element, a device for hardening the adhesive.

After the connection element has been applied and possibly hardened, the fastening device is loosened and the folding fiberboard is now directly ready for shipment, without any further manipulation having to be carried out. In relation to this, the fact that the visible surface is protected from damage or soiling from the start of processing is shown to be advantageous. In the method according to the invention, dripping adhesive, dust or damage are eliminated by means of saws and cutters arranged on the visible side.

Depending on how the production plants are designed, the devices for carrying out the procedures are locally fixed or mobile, so that the panel or fiber parts are processed either in the passage or in the rest position (in a timed manner). In relation to the higher performance in continuous fabrication for means of paths or transport lines, the devices for carrying out the process, the clamping devices, the saws or cutters for processing the connecting edge and the devices for the application of the The connecting element are preferably arranged locally fixed and the panel parts are moved in front of the devices. However, it can certainly prove also convenient to move the devices for carrying out the process and the parts of the fiber panel in the same direction, or in the opposite direction, in carrying out the process.

Examples of embodiments of the invention are described in detail below on the basis of figures. In particular: Figure 1 shows a perspective representation of two parts of a fiber panel or sheet after separation;

Figure 2 shows a perspective representation of two overlapping and oriented fiberboard parts; Figure 3a shows a perspective representation of two fiberboard parts machined on a connecting edge;

Figure 3b shows a perspective representation of two parts of fiberboard machined on a connecting edge;

Figure 4 shows a perspective representation of two parts of fiberboard foldably connected by means of a connecting element;

figure 5 shows a side view of two panel parts, connected by means of a synthetic adhesive, in the folded state;

figure 6 shows a side view of two parts of the fiber panel, connected by means of a synthetic adhesive, in the folded state;

figure 6a shows a side view of the two parts of the fiber panel according to figure 6, connected by means of a synthetic adhesive, in the folded-open state; Figure 7 shows a side view of two parts of fiberboard connected by means of a bonded fabric tape.

The continuous manufacture of foldable fiber sheets or panels, which are used in particular as rear walls for furniture, generally follows directly from the manufacture of an endless web of fiber sheets or panels. The endless fiberboard covered at least on one side is at least as wide as the maximum width of the rear walls of furniture and has a thickness between 1.5 mm and 8 mm. The endless fiberboard is cut to length, by means of separation saws, to the length required for the back walls of furniture. The fiberboard shortened to the suitable length must now possibly still be cut to the suitable width to achieve manageable transport dimensions - in particular for furniture, which is offered as a construction complex in flat packages, the fiberboard must frequently present only the half-width of the piece of furniture considered. Therefore the fiberboard must be foldable. The process for manufacturing such foldable fibreboard must allow, as a continuous process, the simple and economical manufacture of a large number of pieces.

Figure 1 shows two parts of hard fiber sheets or panels 2a, 2b with a material thickness of about 3.5 mm, which parts are coated on the visible side 4 with decorative paper. The canvas side 6 is not processed and is not coated. The parts 2a, 2b have, after separation, mutually opposite outer edges 10, 12. The outer edges 10, 12 after the separation cut are clean and oriented parallel to each other. Parallel to the outer edges 10, 12, however in correspondence with the opposite ends 2a, 2b, the connecting edges 8a, 8b extend which in the starting fiber panel are located on the outside. The definition of "connecting edges" indicates that the panel parts 2a, 2b are connected to each other in an oscillatable, or foldable manner, by means of a connecting element 16 arranged in the area of these edges 8a, 8b. The connecting edges 8a, 8b have irregularities and are not yet prepared for the application of the connecting element 16.

The two parts 2a, 2b are folded towards each other with the visible sides 4 - as shown in Figure 1 by the arrow P and illustrated in Figure 2 - by means of rotation or overturning devices, not illustrated. For example, tilting stars or even simple lever arrangements or scissor tippers can be used as tilting devices. Tipping devices can be simple, as no great precision is needed.

After rotation, the connecting edges 8a, 8b are arranged one above the other. The parts 2a, 2b of the fiberboard are then oriented in such a way that the connecting edges are flush one above the other. For the orientation, simple stops are sufficient, on which the outer edges 10, 12 rest. The parts 2a, 2b oriented, i.e. aligned, flush are fixed by means of removable clamping devices, preferably pairs of clamping rollers 14 (direction of pressure: arrow F in figure 2), which are arranged respectively above and below the two parts 2a, 2b. However, springs, pressure rollers or the like are also suitable. The locking device can also be combined with a transport means, for conveying the parts 2a, 2b, for example in the manner of a pair of conveyor belts with pressure rollers.

The parts 2a, 2b thus fastened are now machined in the area of the connecting edges 8a, 8b, to create a supporting and adhering surface suitable for a connecting element 16. The machining is conveniently carried out with cutters or saws. In the simplest case, the connecting edges 8a, 8b are chamfered, as shown in Figure 3a, so that the parts 2a, 2b have an approximately 7> wedge-shaped profile. If the connecting element 16 itself has a certain thickness of material, so that it could protrude outwards after being applied on the fabric side 4, the processing of the connecting edges 8a, 8b can also lead to a scaled profile according to figure 3b. Concave or convex shaped connecting edges 8a, 8b can likewise be produced for special use cases.

After processing of the connecting edges 8a, 8b, the connecting element 16 is applied. The connecting element 16 is, as illustrated in Figures 5 to 6, preferably a suitable synthetic fusible adhesive, preferably a polyurethane adhesive. . A suitable adhesive is, for example, Jowatherm (R) Reaktant (manufacturer: Lobers and Frank GmbH & Co. KG, Demolt).

The adhesive is applied by means of a suitable shaped nozzle (not shown here), the shape of which ensures that the adhesive is fully applied to the machined connecting edge 8a, 8b, and that an intended profile for 1 'is maintained. connecting element 16. Examples for such pre-assigned profiles are illustrated in Figures 5 to 6. In relation to this, the profiles are chosen in such a way that they stabilize the parts 2a, 2b, of the fiber panel in the folded-open state as they fill the free space originating by processing the connecting edges 8a, 8b (see Figure 6a). The adhesive application device is optionally arranged directly upstream of a device for hardening the glue, for example a cooling system or an ultraviolet or UV system. By this expedient it is ensured that precisely then, if a preassigned profile is to be maintained, the adhesive is fixed, directly after application, in the preassigned form.

Figure 7 shows panel parts 2a, 2b, which have profiled connecting edges 8a, 8b. The connecting edges 8a, 8b comprise a lowering 18a, 18b and a chamfer 20a, 20b. The advantage of this profile is that the adhesive tape used here of fabric, despite the thickness of the material, after application does not protrude from the fabric sides 6a, 6b of the panel parts 2a, 2b. This is particularly advantageous in the stacking of foldable fiber sheets or panels, because completely flat stacks are packed.

Another, however particularly preferred, embodiment of the method according to the invention provides that the outer edges 10, 12 of the fiber panel parts 2a, 2b serve as connecting edges, so that the edges, produced by the separation cut , become the outer edges of the foldable fiberboard. This procedure has the advantage that the absolutely parallel edges, originating from the separation cut, provide a suitable closure of the foldable fiber panel, while the outer edges 10, 12 certainly still require processing. Therefore, if the outer edges 10, 12 are used as connecting edges, then, by processing these connecting edges, a working step is missing, since the rectilinear execution of the outer edges of the fiber panel is missing. folding. In relation to the extreme cost pressure, which charges these products, this creates a clear cost advantage.

It is obvious that the arrangement, described above, of the means for processing the fiber panel or sheet parts and of the means for applying the connecting element, as well as possibly for hardening the connecting element, on the side of the transport line or path, respectively laterally to the panel or sheet, with respect to the arrangement of these means centrally above the fiber panel, also contributes to the reduction of costs. The aforementioned devices are easier to monitor and set and the correct application of the connecting element is easier to implement and can be carried out directly after application. Should unwanted deviations occur here, the corresponding devices can be set again without time delays.

In the process according to the state of the art, the temporal distance between the process control and the product, which takes place only when the panel parts connected to each other are folded, is considerably greater, and correspondingly also the percentage of rejects. Furthermore, there is a danger that damage, which occurs as a result of faulty handling of the folding fiber panels under conditions of overstressing of the connecting elements, will be regarded as faulty processing of the aforementioned devices. Therefore, overcorrections are activated, which lead to further waste production. It is obvious that the method according to the invention is cheaper, simpler and safer to operate than in the state of the art.

Claims (10)

Claims 1. Process for manufacturing foldable fiber panels, which have at least one visible side (4), with at least two parts (2a, 2b) of fiber panel, which are connected to each other, at least zonally, along a connecting edge (8a, 8b) by means of a connecting element (16), with the following steps: - separation of a fiber panel by means of a separation cut in at least two parts (2a, 2b) of fiber panel; - overlapping of the two parts (2a, 2b) of the fiber panel, where the visible sides (4) face one another; - flush alignment of the fiber panel parts (2a, 2b), at least along the connecting edges (8a, 8b), on which the connecting element (16) is arranged; - removable fixing of the two parts (2a, 2b) of the fiber panel; - working of the connecting edge (8a, 8b) on each of the parts (2a, 2b) of the fiber panel; - application, and possibly hardening, of the connecting element (16). Method according to claim 1, characterized in that the connecting element (16) is a synthetic adhesive, in particular a polyurethane-based melt adhesive. Method according to claim 1, characterized in that the connecting element (16) is a tape, possibly coated with adhesive. Method according to at least one of claims 1 to 3, characterized in that the connecting edge (8a, 8b) is profiled during processing. Method according to at least one of claims 1 to 3, characterized in that the connecting edge (8a, 8b) is chamfered during processing. Method according to at least one of claims 1 to 5, characterized in that hard fiber boards or medium density fiber boards are processed. Method according to at least one of claims 1 to 6, characterized in that locally fixed means are provided for fixing the oriented or aligned parts (2a, 2b) of the fiber panel, means for processing the edge (8a, 8b) on which the connecting element (16) is arranged, and means for applying the connecting element (16), and by the fact that the fiber panel parts (2a, 2b) to be the connecting elements are passed continuously in front of these means, to work the connecting edges (8a, 8b) and to apply the connecting element (16) to the edges (8a, 8b) of at least two parts (2a, 2b) of fiberboard. Method according to at least one of claims 1 to 6, characterized in that the means for processing the edges (8a, 8b), on which the connecting element (16) is arranged, and the means for the application of the connecting element (16), they are passed in front of the aligned and fixed fiberboard parts (2a, 2b), to work the connecting edges (8a, 8b) and to apply the connecting element (16 ) at the edges (8a, 8b) of at least two parts (2a, 2b) of fiberboard. Method according to at least one of the preceding claims, characterized in that the fiber panel parts (2a, 2b) are mutually superimposed with the visible sides (4) in such a way that the edges (8a, 8b) become originating through the separation cut, they form the outer edges (10, 12). Method according to at least one of the preceding claims, characterized in that during or after processing the connecting edges (8a, 8b) and applying the connecting element (16), further edges (10, 12) are processed parts (2a, 2b) of fiberboard, or by the fact that the surfaces of parts (2a, 2b) of fiberboard are machined.