DE69708613T2 - METHOD AND DEVICE FOR PRODUCING A MINERAL FIBER PANEL - Google Patents

Abstract

Process for producing mineral fibreboard comprises a fleece of greater than twice the finished product thickness (2 t) being compressed (17) to a first thickness of 0.8-1.5 (preferably 0.9-1.3) t without longitudinal compression to a weight per unit area of W. The fleece is then longitudinally compressed by roller systems (30,32) without pleating to a unit weight of 2-10 W and a thickness of 1-1.3 and preferably 1-1.1 t. The fleece is then tightly held and fed to a bonding oven (25).

Description

The invention relates to a method and a device for producing a mineral fiber board.

Various improvements in the production of mineral fiber boards have been revealed in recent years. A significant improvement in the properties of the mineral fiber boards can be achieved, for example, by reorienting the fibers during the production process so that they are predominantly aligned perpendicular to the large board surfaces. The compressive strength and the tensile strength perpendicular to the board plane can be significantly increased as a result.

Various methods are known by which the fibres are reoriented so that the product acquires a pleated arrangement, but improved performance is usually obtained when the final product is substantially free of pleats. Many different methods have been disclosed for longitudinally compressing a fibrous web, either to form a pleated or to form a substantially unfolded product. One such method is disclosed in WO 92/10602. Another is disclosed in DE-A-16 35 620. From their description and drawings it can be seen that the extent of longitudinal compression is quite small (35% as a maximum in the examples) and that this may be accompanied by a slight increase in thickness during longitudinal compression.

Many processes involving longitudinal compression also include a significant thickness compression step after longitudinal compression and before final curing. For example, in EP 133 083 a web is subjected to significant longitudinal compression in several stages and then subjected to thickness compression upon entering the curing oven. The resulting product has a substantially isotropic fiber orientation.

Other disclosures of longitudinal compression carried out in such a way that folding is avoided can be found, for example, in US 4,567,078, WO 91/14816 and WO 94/16164.

It would be desirable to develop a process for longitudinal compression that avoids significant folding of the starting web but results in significant improvements in properties compared to those obtainable by known longitudinal compression processes. In particular, it would be desirable to produce mineral fiber boards having improved physical properties, such as improved compressive strength and/or tensile strength and better insulation values. It would be particularly desirable to be able to achieve these improved results with fewer resources, such as reduced fiber quantity and possibly less binder.

According to the invention, a continuous process for producing a bonded mineral fiber board with a thickness t from a fleece with a thickness of more than 2 t is provided, which comprises

compressing the fleece in the depth direction essentially without simultaneous compression in the longitudinal direction to a first thickness and a weight w per unit area,

subsequently compressing the web in the longitudinal direction, forcing the web to a second thickness, thereby producing a longitudinally compressed web, transporting the longitudinally compressed web to a binding station (25) and

binding the fleece in the binding station (25) to form a bonded mineral fibre board,

characterized in that the first thickness is in the range of 0.8 to 1.5 t, preferably between 0.9 and 1.3 t,

the second thickness is in the range between 1 and 1.3 t, preferably 1 to 1.1 t, the compression in the longitudinal direction is carried out continuously or in one or more stages essentially without folding the fleece and a Longitudinally compressed fleece with a weight per unit area of 2 to 10 w is produced and

the breaking of the fleece is prevented during transport between the stage of longitudinal compression and the bonding stage.

Since the compressed web has a weight per unit area of 2 to 10 w, this is essentially equivalent to saying that compression in the longitudinal direction can be achieved to about 0.5 to 0.1 times the original length of the web.

The invention also includes methods for the continuous manufacture of a bonded mineral fibre board, in which a fibre felt is pre-compressed in the thickness direction to a thickness of 1 to 3 times the thickness of the final product (preferably to substantially the same thickness as the nominal thickness of the final product) and then subjected to compression in the longitudinal direction by means of at least two conveyor pairs driven at different speeds to produce a felt compressed in the longitudinal direction and then bonded in a bonding station (25) to give a bonded mineral fibre board, characterized in that the thickness of the felt in the longitudinal compression stage or before the bonding station is approximately between 0.9 and 1.3 times the thickness of the final product, the longitudinal compression is effected substantially without compression in the thickness, the longitudinal compression is effected to approximately 0.5 up to 0.1 times the original length, the compression is effected in a continuous compression zone and the felt is held to prevent breakout between the longitudinal compression unit and the binding station.

The invention also includes a new device as defined in the claims.

Since the web is under considerable longitudinal compression, it tends to bunch up away from the conveyor through which it is being transported and so suitable means must be used to constrain the web against breakaway (i.e., buckling up away from the support) during transport between the longitudinal compression unit and the bonding station. These constraining means may comprise a belt, rollers or other guides which adequately constrain the longitudinally compressed web to the desired longitudinal path and prevent significant deviation of the web from the desired path.

It has surprisingly been found that, compared with the known state of the art, products with significantly better properties can be produced using the new process. In contrast to the known products, the new products are distinguished by a very homogeneous density. The fibers are evenly folded and no preferred fiber orientation can be determined (Fig. 12). On an enlarged scale, it has been found that the randomly oriented fibers are partially arranged in a wave pattern.

Compared to conventional processes, considerable resource savings can be achieved with the process according to the invention. In particular, the amount of fiber required to achieve specific physical values can be reduced by up to 15 to 25%. The products manufactured by the new process are therefore much lighter than conventional products with the same physical properties. Since the production costs depend essentially on the amount of fiber used, considerable cost savings can also be achieved with the new process.

In the pre-compression stage, the relatively loose fleece is pre-compressed to a specific weight w (kg/m²) and then in the longitudinal compression unit, which can also be referred to as an optimization unit, further compressed to the final weight. Contrary to expectations, the extremely high compression of the already pre-compressed web to 2 to 10 times, preferably 2 to 6 times, the weight of the pre-compressed web does not lead to any folding on the web surface during the process. An increase in weight/area unit of the web or felt can be obtained by suitable compression of the web in the longitudinal direction with essentially equal distances between the upper and lower conveyors, e.g. corresponding to the nominal thickness of the final product.

Although longitudinal compression of the web may be accomplished in a series of stages, it is preferred that longitudinal compression of the web be accomplished in one stage, with the longitudinally compressed web and bonded sheet having a weight per unit area of 2 to 6 times, preferably 2.5 to 5 times, and most preferably 2.5 to 3.5 times the weight of the pre-compressed web. The resulting products have high compressive strength and good insulating value.

Advantageously, the compression in the longitudinal direction is effected by feeding the fleece by means of a first conveyor to a second conveyor, the second conveyor being driven at a lower speed than the first conveyor. The conveyor can consist of belt, roller or chain conveyors. However, roller conveyors are preferably used because the raw microdensities obtainable with them are extremely homogeneous. The roll diameter and the distance between the rolls in the conveying direction or the distance between the conveyors are preferably such that any breaking or folding of the fleece is made essentially impossible. The distance between two adjacent rolls is preferably between 1 and about 50 mm, advantageously between 2 and 30 mm and most preferably less than 20 mm. The permissible roll distance depends essentially on the density of the fleece, the degree of longitudinal compression in the compression unit and the thickness of the plate for production. With a small roll distance, it is possible to manufacture products of varying thickness and high density. Although the rollers can be driven individually, in a preferred embodiment they are assembled into groups, each of which comprises several rollers.

The method according to the invention makes it possible to produce products that preferably have a density of between 40 and 200 kg/m³. In a particularly advantageous variant, the nonwoven is stretched in the conveying direction after compression in the longitudinal direction. For this purpose, the nonwoven can, for example, first be overcompressed with regard to the required thickness of the final product, e.g. by 20 to 40%, and then decompressed by stretching. This helps to avoid undesirable folding of the nonwoven web. The raw microdensity can also be improved. Decompression by stretching can be particularly important for high-density products, e.g. for products with a density of more than 140 kg/m³. The compression and decompression processes can also be repeated.

The fleece can consist of glass wool fibers, rock wool fibers or other artificial fibers. However, the fleece preferably consists essentially of rock wool fibers or other artificial glass-like fibers and contains uncured binder. The binder content is often between about 0.7 and 7% by weight, generally 1 to 4% by weight. The binder can preferably be cured in a curing oven. However, the fleece can also be bonded by needling or felting instead of or in addition to bonding by curing a binder.

Advantageously, mineral fibres with an average length of between about 0.3 and 50 mm, preferably between about 0.5 and 15 mm, and a thickness of between about 1 and 12 µm, preferably between about 3 and 8 µm, are used. However, mineral fibres with an average length of between about 1 and 10 mm, preferably between about 2 and 6 mm, and an average thickness of about between 2 and 10 µm, preferably between about 3 and 6 or 7 µm. The average length of rock wool fibres, which are usually shorter than glass fibres, is typically 2 to 4 mm and the average diameter is 3 to 4 µm.

Advantageously, the predominant orientation of the fibers is changed or partially compensated during the deposition of the web on the conveyor. This can be done, for example, by means of a rotary element suitable for oscillating at an angle to the transport direction or by means of an air curtain. In this way, the density distribution of the web can be improved and the fiber orientation changed, which has a favorable effect on the mechanical properties of the resulting products. Advantageously, the primary web is deposited in layers on the collecting belt by means of a pendulum belt suitable for oscillating at an angle to the transport direction. In this way, the primary web is preferably formed by cross-laying one on top of the other. In this way, the fibers are partially reoriented and the homogeneity (transverse distribution) of the web deposited on the collecting belt can be improved.

Advantageously, 2 to about 60 layers, preferably between 2 and 40 to 50 layers, are placed on top of each other. Under these conditions, a certain reorientation of the fibers is obtained.

The fleece can, for example, be deflected transversely to the transport direction, whereby at the same time a compression, in particular a compression in the longitudinal direction, is carried out.

In a particularly preferred variant, the fleece compressed in the thickness and length direction is divided into two or more sub-webs parallel to the large surfaces, while the sub-webs are each attached to the opposite large surfaces to prevent deformation in the thickness direction. At least one of the webs is compressed in the thickness direction and/or lengthwise direction and the sub-webs are then combined and subsequently bonded. This process can be used to produce multi-layer products.

Although the adhesion of the sub-sheets by curing the binder is normally sufficient, the contact surfaces of the sub-sheets may be sprayed or impregnated with a binder before they are joined. In principle, the joined sheets, held together by a suitable device, may be compressed again in thickness. It is advantageous, however, to compress the sheets longitudinally before bonding. The longitudinal compression may be in a ratio of 1.1:1 up to a maximum of 2:1. The contact surfaces may be increased by a final longitudinal compression so that the bonding of the sub-sheets is improved.

Although the new device may have individually driven rollers, it preferably comprises at least two roller groups of two or more rollers. Preferably, at least about 10 to 12 rollers are provided in the compression unit to compress the felt. The compressed felt can thus be given an advantageous corrugated fiber structure. Other advantageous embodiments are defined in the subclaims. The invention also comprises a method for continuously producing a single-layer or multi-layer fiberboard, in which method a fiber felt is subjected to pre-compression and, by means of at least two conveyor pairs driven at different speeds, to compression in the longitudinal direction or to compression in the longitudinal/thickness direction and then fixed, characterized in that the fiber felt (20) is pre-compressed to about 1 to 3 times, usually about 1 to 1.5 times, the nominal thickness of the final product and then subjected to a compression process in the longitudinal/thickness direction or only to a compression process in the longitudinal direction in an optimization unit (19) by means of conveyors each having two opposing roller groups each comprising two or more rollers, wherein the compression in the longitudinal direction is carried out to 0.5 to 0.1 times the original length in a continuous or quasi-continuous compression zone and substantially the nominal thickness of the final product is achieved in the optimisation unit.

The invention also includes a device for carrying out the method described above, which comprises at least one collecting belt for receiving a fiber felt, a pre-compression stage for compressing a fiber felt, at least two successive conveyors driven at different speeds for compressing the fiber felt in the longitudinal direction or in the longitudinal/thickness direction and a curing oven for fixing the fiber felt compressed in the longitudinal direction and in the thickness direction, characterized by an optimization unit comprising conveyors each having two opposite groups of rollers each comprising two or more rollers, so that during the process a continuous or quasi-continuous compression zone extending over a plurality of rollers or groups of rollers is obtained.

The preferred variant in which the longitudinally compressed web is divided into two or more sub-webs, at least one of which is then longitudinally compressed before being reunited, is a process of wider applicability and greater value than being used only as a second step in the inventive process described above.

It is already known to divide a web in thickness direction into sub-webs in order to compact one of them and then reunite and cure them, e.g. from CA-A-1057183, WO 88/00265, WO 92113150, WO 94/16162 and EP-A-277 500. Known methods have various disadvantages. For example, the lower web is often only pre-compressed, so that the final product has a relatively low compressive strength Although the compressive strength in the vertical direction can be improved by folding the web, this deteriorates the flexural strength. These methods also have the disadvantage that the backing layer is only slightly compacted and essentially no rearrangement of the fiber orientation occurs, except possibly by folding.

According to another aspect of the invention, a continuous process for producing a two-layer or multi-layer bonded mineral fiber board from a mineral fiber fleece is provided, in which the fleece is pre-compressed as described above, the pre-compressed fleece is fed to a separating device, the fleece is separated into two or more sub-webs by means of the separating device (41), at least one sub-web is compressed in the thickness direction, the sub-webs are then combined and transported to a bonding station, in which the fleece is bonded, and the breaking out of the sub-webs under tension between the compression unit and the binding station is prevented by a restricting device.

As described above, a new device is also provided which comprises a first transport device for transporting the web to a separating device, a separating device for separating the web into two or more sub-webs, a device for compressing at least one sub-web in the thickness direction, a second transport device for subsequently combining the sub-webs and transporting them to the binding station in which the web is bound, the first transport device comprising the device for compressing in the longitudinal direction and comprising at least two conveyor pairs arranged successively in the conveying direction, and wherein a device is provided for preventing the break-out of the sub-webs under tension between the compression unit (19) and the binding station.

The methods and devices of this aspect of the invention differ from the known methods and devices essentially in that the pre-compressed web is further compressed in thickness and/or length direction. As a result of the use of the initial compression, the produced sub-webs can already have relatively high densities and different fiber structures before they are divided. The advantage of this, for example in two-layer boards, is that the lower density layer has better compressive strength and tensile strength perpendicular to the large surfaces, unlike in conventional boards. Compared to known methods, a specific tensile and compressive strength can therefore be achieved with a reduced amount of material, in particular a smaller amount of fiber.

To prevent the nonwoven webs from breaking or folding under tension between the compression unit and the binding station, a suitable hold-down device and/or suitable conveyor systems are advantageously provided to hold the nonwoven webs on the larger surfaces.

In order to form a highly compacted top layer, at least one of the split bottom webs can be compressed in thickness. In this way, a higher puncture resistance can be obtained. Advantageously, however, the one bottom web compressed in the thickness direction can also be compressed in the length direction. The flat rolling of the reoriented fibers by the thickness compression may require compensation for the resulting increase in length.

To improve the bond between the sub-sheets, a binder can be applied to the contact surfaces of the sub-sheets before joining. In many cases, however, the amount of binder initially applied to the fibers is already sufficient to obtain a good bond between the sub-sheets when the binder hardens. Another way to improve the bond between the sub-sheets is to compress the combined sheets in the longitudinal direction before hardening. By pulling the sheets together, e.g. in a ratio of 1.1:1 up to a maximum of 2:1, it is possible to increase the contact surfaces and thus obtain a better bond between the layers.

A difficulty associated with the continuous production of two-layer or multi-layer products can be the contamination of the band knife, which occurs due to the binding agent adhering to the fibers. An advantageous variant of the process therefore proposes to continuously clean the separating device. This can be done, for example, with the help of a jet of solvent, e.g. water, directed at the cutting edge of the band knife.

The compression in the longitudinal direction is advantageously carried out by passing the fleece through a compression unit comprising several conveyor pairs arranged one after the other in the conveying direction, the speed of at least one conveyor pair being lower than that of the preceding conveyor pair. The pre-compressed fleece is advantageously compressed in the longitudinal direction in at least one stage. The compression in the longitudinal direction enables the fibers to be reoriented so that in particular the compressive strength and tensile strength perpendicular to the large surfaces are improved. As a result of the optimization of the fiber structure, it is possible to reduce the resources used.

To produce products with a folded fiber structure, the distance between the opposite conveyors of a conveyor pair is advantageously set to approximately 0.5 to 0.1 times the distance between the following conveyors, the conveyor path being defined by the two conveyor pairs, which are arranged in essentially the same alignment and the peripheral speed of at least the directly following pair being lower than the peripheral speed of the preceding conveyor pair. In this way, it is possible to produce a nonwoven web with a folded fiber structure (Fig. 2).

Before entering the compression unit, the fleece is advantageously already compressed to approximately 0.8 to 1.5 times, preferably 0.9 to 1.3 times, the nominal thickness and most preferably to approximately the nominal thickness of the end product, so that the conveyors of the compression unit essentially only result in compression in the longitudinal direction. The compression in the longitudinal direction can take place in a continuous compression zone in which the nominal thickness of the product is maintained. Surprisingly, a very homogeneous raw microdensity can be obtained if the fleece is already pre-compressed to approximately the nominal thickness of the end product before the compression unit and is then only compressed in the longitudinal direction. The mineral fiber fleece is advantageously compressed in the longitudinal direction by a factor of 2 to 10, preferably by a factor of 2.5 to 5 and most preferably by a factor of about 2.5 to 3.5. In some cases, e.g. if the density of the lower web of the end product is to be less than about 100 kg/m³, simultaneous compression in the longitudinal and thickness directions may be indicated. The degree of thickness compression is advantageously less than 2 and preferably less than 1.5.

Although the conveyors of the compression unit can be conveyor belts, in a particularly preferred embodiment the conveyors are constructed as roller conveyors. Unlike conveyor belts, rollers have the advantage that the web is repeatedly expanded and compressed during compression by the rollers. As a result, the products surprisingly have a very homogeneous raw microdensity (density distribution in a small volume unit) and very good mechanical properties, such as compression, puncture and tensile strength, in products with considerably reduced weight compared to conventional products. The fibers are folded evenly and a preferred fiber orientation is not detectable (Fig. 11). On an enlarged scale it has been found that the randomly oriented fibers are partially arranged in a wave pattern. This type of fiber structure is referred to by the inventors as a wave fiber structure. Another beneficial effect consists in the compaction of the nonwoven web surfaces, which is possible with the help of rollers.

Although the individual rollers can each be controlled individually, in an advantageous embodiment each roller conveyor comprises two opposing groups of at least two rollers, whereby the rollers of a conveyor are each driven at the same circumferential speed. Since the rollers are combined in groups of at least two rollers, the compression unit and its control are greatly simplified. The fleece is advantageously stretched in the conveying direction before the separating device. The expansion of the fleece can prevent undesirable folding or breaking of the fleece web, for example during the transition from the compression unit to the separating device.

The fleece can be made of glass wool, rock wool or other artificial fibers. However, the fleece preferably consists essentially of rock wool fibers and contains an uncured binding agent. The binding agent content can be between 0.7 and 4 percent by weight. The binding agent can preferably be cured in a curing oven. The fleece can also be bound by needling or felting.

Advantageously, mineral fibers with an average length of approximately between 0.3 and 50 mm, preferably between 0.5 and 15 mm, and a thickness of approximately between 1 and 12 µm, preferably between 3 and 8 µm, are used. However, it is also possible to use mineral fibers with an average length of approximately between 1 and 10 mm, preferably between 2 and 6 mm, and an average thickness of approximately between 2 and 10 µm, preferably between 3 and 7 µm. The average length of the rock wool fibers, which are usually shorter than glass fibers, is usually 2 to 4 mm and the average diameter is 3 to 4 µm.

Advantageously, the predominant orientation of the fibers is changed or partially compensated during the deposition of the web on the conveyor. This can be done, for example, by means of a rotary element suitable for oscillating at an angle to the transport direction or by means of an air curtain. In this way, the density distribution of the web can be improved and the fiber orientation changed, which has a favorable effect on the mechanical properties of the resulting products. Advantageously, the primary web is deposited in layers on the collecting belt by means of a pendulum belt suitable for oscillating at an angle to the transport direction. In this way, the fibers are partially reoriented and the homogeneity (transverse distribution) of the web deposited on the collecting belt can be improved.

Advantageously, 2 to about 60 layers, preferably between 2 and 40 to 50 layers, are placed on top of each other. This leads to a certain reorientation of the fibers.

The fleece can, for example, be deflected transversely to the transport direction, whereby at the same time a compression, in particular a compression in the longitudinal direction, can be carried out.

According to a preferred illustrative embodiment, at least the separating device and the following hold-down device are adjustable perpendicular to the belt surface in the region of the multi-layer unit independently of one another, so that the device can be used selectively for the production of single-layer or multi-layer products.

Advantageously, the device for compressing the at least one lower web comprises at least two independently driven conveyor pairs. In this way, the divided lower web can also be compressed in the longitudinal direction. The conveyor pairs are advantageously roller conveyors whose Roller spacing is adjustable. As a result, the base webs can be compressed in both thickness and length.

The binding station advantageously consists of a hardening oven, with coolable feed rollers being provided in front of the oven. In this way, adhesion of the binding agent to the rollers can be prevented and clumping avoided. In an advantageous embodiment, the peripheral speeds of the transport device between the separating device and the binding station and the peripheral speed of the conveyor belts in the oven can be adjusted separately, so that, for example, compression or decompression can also be carried out in front of the hardening oven.

Illustrative embodiments of the invention are described below with reference to the drawings:

Fig. 1 shows a mineral wool product manufactured by thickness compression and having a fiber orientation that is substantially parallel to the surface.

Fig. 2 shows a folded product comprising a major portion of fibers arranged perpendicular to the surfaces.

Fig. 3 shows a two-layer product, with the upper layer having an increased density.

Fig. 4 shows a product with essentially homogeneous density and randomly oriented fibers.

Fig. 5 shows a product in which a layer with randomly oriented fibers is combined with a layer with increased density.

Fig. 6 is a simplified view of an apparatus for producing a single-layer mineral fiber board a) in a continuous process or a continuous compression zone and b) in a single-stage process.

Fig. 7 is a diagram showing the principle of an apparatus for continuously producing a single-layer or multi-layer mineral fiber board with different densities, a) in a continuous process or a continuous compression zone and b) in a one-stage process.

Fig. 8 is an elevational view of a compression unit in detail.

Fig. 9 is a side elevation of the compression unit of Fig. 8.

Fig. 10 is a plan view of the compression unit of Fig. 8.

Fig. 11 shows the fracture zone of a) a plate with essentially parallel fiber orientation and b) and c) of rock wool fiber plates according to the new method and pulled apart perpendicular to the plate plane.

Fig. 12 is a perspective section through a two-layer plate, showing the fiber structure on an enlarged scale, and Fig. 13 is a diagram showing various possible arrangements for four conveyor pairs arranged sequentially in the conveying direction.

Figures 1 to 5 illustrate the fiber orientations that often occur in insulating boards. Boards with fibers arranged parallel to the surface (Fig. 1) have comparatively poor mechanical properties. To compensate for this disadvantage, the fibers are often reinforced with binder and the density is increased.

Products with fibres arranged perpendicular to the surface can be obtained if a sheet of the type shown in Fig. 1 is cut into strips, the strips are rotated through 90º and then bundled. This method of manufacture is complex and accordingly uneconomical. According to another method of manufacture, the fleece is folded (folding process, Fig. 2). These products have a much better compressive and tensile strength perpendicular to the plane of the sheet than sheets of the type shown in Fig. 1. Sheets with folded fibres can be bent and can therefore be used for insulating pipes or for lining curved surfaces. On the other hand, a disadvantage of these products is that they tend to break along the fold and the puncture resistance is not adequate. Another disadvantage of known products of this type is that there can be relatively considerable differences in density within the sheet.

Fig. 3 shows a two-layer product in which the top layer has an increased density. These products are suitable for applications requiring high wear resistance or increased surface protection. As a result of the increased density of the top layer, the average density can be reduced.

Fig. 4 shows a product with a substantially isotropic fiber orientation with a substantially random fiber orientation. These products have excellent mechanical properties such as high compression, wear and puncture resistance and high tensile strength perpendicular to the plane of the plate. They do not break and the thermal conductivity is essentially the same as that of the products shown in Fig. 1. In general, these products are lighter than comparable products with substantially parallel fibers with comparable or improved mechanical properties.

Fig. 5 shows a product in which the advantages of the increased density of the top layer and the fiber structure shown in Fig. 4 are combined. The aim of the invention Furthermore, it consists in particular in improving the properties of the products of the type shown in Figures 4 and 5.

The device 11' shown in Fig. 6 for carrying out the method according to the invention comprises, when viewed in the conveying direction F, a pre-compression stage 17', an optimization or compression unit 19' adjacent to the pre-compression stage 17' and consisting of two conveyor pairs 30, 32 for compressing the felt or the fleece, and also a conveyor belt 40 and a hold-down belt 42 and feed rollers 63, 65 for transporting the compressed fleece to a curing oven 25. Finally, conveyor belts 67, 67' are provided in the curing oven 25 to transport the compressed fleece through the oven and to hold it on the opposing large surfaces during the curing of the binder.

The pre-compression stage 17' consists of a lower conveyor belt 27 and a press belt 29. With the help of the pre-compression stage 17', the primary fleece, which is preferably laid down in layers on a collecting belt 15, is pre-compressed to such an extent that the fleece marked with the reference number 20 can be introduced into the compression unit 19'. For this purpose, the press belt 29 is adjustable in terms of height.

The conveyor pairs 30, 32 of the compression unit 19' consist of upper and lower roller groups 30', 30" and 32', 32", each consisting of six rollers 39. The upper and lower roller groups 30', 30", 32', 32" each have a separate drive (not shown in detail) so that the conveyors can be driven at different speeds. The upper roller groups 30', 32' are also adjustable in height so that the device 11' can be used to produce products of different thicknesses. The distance between the upper and lower roller groups 30', 30", 32', 32" is preferably identical.

To carry out the method of the invention, the web is pre-compressed in the pre-compression stage to approximately the nominal thickness of the final product and then compressed longitudinally by a conveyor at a distance approximately equal to the nominal thickness of the final product. In these circumstances, the conveyor 30 is driven at a first speed and the conveyor 32 at a second speed, usually not more than half the first speed, so that a corresponding compression of the web 20 in the longitudinal direction results. In principle, another conveyor could be provided to expand the web somewhat in the longitudinal direction after compression. The last step can prevent the highly compressed web from folding or breaking out in an upward direction during transport to the curing oven 25.

The compression unit 19 is followed by a conveyor belt 40 and a hold-down device 42 to restrict the compressed fleece 20 from breaking out, i.e. bulging upwards away from the conveyor 40. The hold-down device 42 consists of an unwindable, relatively strong belt that is placed on the transported fleece web. The belt can additionally be loaded with applied weights. Feed rollers 63, 65 are provided in front of the curing oven 25 and are preferably coolable. The distances between the lower and upper roller groups are each advantageously set to approximately the nominal thickness of the end product. This has the advantage that once the fiber orientation in the compression unit 19 has been set, it no longer changes.

The device 11 shown in Fig. 7 differs fundamentally from that shown in Fig. 6 in that the compression unit 19 has four conveyors with four rollers each. A multi-layer unit is also provided, which can be used for the production of multi-layer panels and in principle also together with the device 11'. For simplification, in the following Description, the same reference numerals as in the description of the device 11' are used for similar parts.

The device 11 shown in Fig. 7 for producing mineral fiber boards essentially comprises, arranged in succession in the conveying direction F, a pendulum belt 13 and a collecting belt 15 for the corresponding deposit and collection of the fibers produced in a fiber production unit (not shown in detail), and a pre-compression stage 17 and an optimization or compression unit 19 for forming a felt or a fleece 20 with optimized fiber orientation and homogeneity. The compression unit 19 for optimizing the compression is followed by an optional multi-layer unit 21, which can be used to produce multi-layer mineral fiber boards. The multi-layer unit 21 is followed by a transport device 23 which holds the compressed fleece clamped to the opposing large surfaces and leads it to the binding station, e.g. to a curing oven 25.

The above-mentioned fiber production unit serves for the continuous production of fibers by one of the known methods, e.g. the cascade spinning method. The fibers produced, also referred to as "primary web", are sprayed with a binding agent (not shown) and guided to the pendulum belt 13 by means of a conveyor (not shown). The latter belt is located above the collecting belt 15 and swings transversely to the transport direction of the collecting belt 15. Another orientation of the pendulum movement, e.g. in the transport direction, is also possible. As a result of the pendulum movement, the primary web 26 is deposited crosswise overlapping on the advancing collecting belt 15, as can be seen from Fig. 7, depending on the speed of the latter and the frequency of the pendulum movement. Another device, e.g. gas jets, is also possible for producing as statistical a fiber orientation as possible on the collecting belt. As a result of the forward movement of the collecting belt 15, the predominant orientation of the fibers in an angle to the transport direction. Seen from above, the fibers of the two superimposed fleece layers extend essentially crosswise.

The pre-compression stage 17 consists of a lower conveyor belt 27 and a press belt 29. The latter is adjustable in height so that the fleece 26 can be pre-compressed to different degrees. The pre-compression stage 17 provides a pre-compression and a certain homogenization of the relatively loose fleece 20 before it is introduced into the optimization unit 19. The two belts 27, 29 preferably have individual independent drives so that they can be operated at different circumferential speeds.

According to the exemplary embodiment shown, the optimization unit 19 consists of several conveyors or conveyor pairs 31, 33, 35, 37. Each pair 31, 33, 35, 37 has a lower and an upper roller group, each consisting of four rollers 39. The space between the individual roller groups 31', 31", 33', 33", 35', 35", 37', 37" is adjustable. The roller groups are also designed so that they can be inclined relative to one another, preferably in the transport direction. The latter property enables the fleece 20 to be continuously compressed or decompressed in thickness on the way through a conveyor pair 31, 33, 35, 37.

A number of different approaches to fleece optimization can be achieved by adjusting the distance between the opposing roller groups and their speeds. In this way, the product properties can be very different. These adjustment devices also make it possible to optimize the fiber structure in a controllable manner and, for example, to avoid undesirable folding on the fleece surface.

At least the lower and upper roller groups 31" and 31' of the first conveyor pair 31 are adjustable in height. This allows the fleece bent as shown in Fig. 7, e.g. to smooth and compact the fleece surface.

The upper and lower roller groups 31', 31", 33', 33", 35', 35", 37', 37" of the conveyor pairs 31, 33, 35, 37 each have a separate drive, which is not shown in detail in Fig. 7. The drives used are preferably infinitely variable within a certain range, so that, for example, the upper and lower roller groups can have different circumferential speeds. A slightly higher circumferential speed of the upper roller group is necessary, for example, if it is not arranged horizontally but at an angle to the lower roller group.

Fig. 8 to 10 show an exemplary embodiment of a compression unit 19 in which the conveyors with the roller groups 31', 31", 33', 33", 35', 35", 37', 37", comprising the rollers 39 are arranged on a support structure 71. Sprockets 115 (Fig. 10) are provided at one end of each roller 39. All four or five rollers 39 are connected by drive chains (not shown) and form a roller group. A drive 117', 117", 117''', 117"", 118', 118", 118''', 118"" is provided for each roller group.

The upper and lower roller groups 31', 31" of the first conveyor pair 31, viewed in the conveying direction (Fig. 9, arrow F), are vertically adjustable. The vertical adjustment of the upper roller group 31' is carried out by means of a drive element 81, which drives the axles 73, 73' via the cardan shafts 77, 77'.

The drive element 83, which drives the axles 75, 75' via the cardan shafts 79, 79', is used for the vertical adjustment of the lower roller group 31".

Unlike the first roller groups 31', 31", the position of the remaining roller groups is either not adjustable (bottom) or only adjustable together (top). As can be seen in particular from Fig. 8 and 9, the rear three lower roller groups 33", 35", 37", viewed in the conveying direction, are arranged on a stationary frame 85, while the upper three roller groups 33', 35', 37' are arranged on a vertically adjustable frame 87. The latter frame 87 is vertically adjustable on the upper part of the support structure 71. Linear guides 93 on the pillars 95, 95', 97, 97' provide vertical guidance of the frame 87. A drive element 103 which drives the axes 89, 89', 91, 91' arranged in pairs on the support structure 71 through the cardan shafts 99, 99', 101, 101' is provided for vertical adjustment of the frame 87.

The upper roller groups 33', 35', 37', the last of which has five rollers 39, are arranged on support rails 105 which are rotatably connected to the frame 87 by the pin 107. In the exemplary illustrative embodiment, the front end of the rails 105, viewed in the conveying direction, is connected to the vertically adjustable frame 87 by another pair of axles 109, 109'. By adjusting the axles 109, 109' it is possible to rotate the support rails 105 upwards or downwards from the horizontal, so that it is possible, for example, to form a path tapering in the conveying direction F. The axles 109, 109' are also connected to each other via the cardan shafts 111, 111', so that here again a drive 113 is sufficient to adjust them.

Fig. 13 shows various ways in which four conveyor pairs can be arranged in principle. However, the settings according to Fig. 13b and 13c cannot be created with the compression unit according to Fig. 8 to 10. An arrangement of the roller groups 31', 31", 33', 33", 35', 35", 37', 37" according to Fig. 13d is recommended if, for example, light products are to be manufactured.

The optimization unit 19, which comprises several conveyor pairs, is followed by the optional multi-layer unit 21, which in the exemplary embodiment shown is a device for two densities. This comprises a separating device 41, e.g. a band saw or a band knife, which is only shown in outline in Fig. 7, for separating the compressed fleece 20 into two webs 43 and 45. The multi-layer unit 21 also comprises conveyors 47, 49, 50 and 51, e.g. conveyor belts, which fix the thickness of the compressed bottom webs 43, 45. Gaps which occur for geometric reasons between the separating device and e.g. the conveyor belt 49 or 50 can be bridged by guide plates where possible. This prevents the fleece web 43, which is compressed to different degrees, from breaking out.

The separating device 41 and the following conveyor are preferably adjustable in height. This enables the fleece emerging from the compression unit 19 to be cut into lower and upper webs 43, 45 of practically any thickness. In addition, the separating device 41 and the conveyor belt 49 can also be moved upwards independently of one another to an extent that they are arranged outside the transport area of the fleece. The conveyor belt 49 then serves as a hold-down belt. Due to the vertical adjustability, the device 11 can optionally be used to produce single-layer or multi-layer panels. In principle, many separating devices and corresponding hold-down belts can be provided in order to make it possible to produce panels with three or even more layers. The distance between the upper and lower rollers is also adjustable so that outer layers of different thicknesses can be produced.

Two conveyor pairs 53, 54, which are provided after the conveyors 50, 51, serve to compress the upper web 45 in the thickness and longitudinal direction. The conveyor pairs 53, 54 preferably comprise rollers, which are combined in each case with three rollers to form upper and lower roller groups. The conveyor pairs 53, 54 can each be driven at different circumferential speeds, so that the increase in length that can occur as a result of the thickness compression can be compensated by subsequent compression in the longitudinal direction. The distance between the upper and lower rollers is adjustable so that outer layers of different thicknesses can be produced.

Conveyor belts, chutes and/or guide plates (not shown in detail) join the compressed web 45' to the lower web 43. In most cases, a hold-down belt for the highly compressed web 45' can be dispensed with. A dosing device 57 for a binding agent is provided in the zone where the webs 43 and 45 meet. With this arrangement, it is possible to apply a binding agent to the contact surfaces of the upper and/or lower webs 43, 45', so that a better bond is obtained after the binding agent has hardened. In most cases, a dosing device 57 can be dispensed with in particular if any increases in length that occur have been compensated for beforehand.

Feeding belts 59, 61 and feed rollers 63, 65 press the combined webs 43, 45' together and transport them into the curing oven 25. The circumferential speeds of the feeding belts 59, 61 and the feed rollers 63, 65 are advantageously separately adjustable so that the compression or decompression of the compressed webs 43, 45' can be carried out as required. At least the feed rollers 63, 65 are preferably coolable. Air-permeable conveyor belts 67, 67' are preferably provided in the curing oven 25. The belts 67, 67' hold the webs 43, 45' together during the curing process and thus essentially determine the nominal thickness of the finished panels. The belts 67, 67' as well as the conveyors 59, 61, 63, 65 are vertically adjustable and can thus be adjusted to the fleece thicknesses that come from the multi-layer unit 21 or the compression unit 19.

The manufacture of a multi-layer board can be carried out as follows: The primary fleece supplied from a collection chamber (not shown) and provided with a binder, in the case of rock wool fibres usually with a weight of about 200 to 800 g/m², preferably 200 to 400 g/m², with an approximate average thickness of 15 to 20 mm or more frequently up to 75 mm, is fed to the The primary web is fed to a pendulum belt 13. The latter deposits the primary web onto the continuously advancing collecting belt 15. Depending on the speed of the latter belt 15 and the frequency of the pendulum belt 13, a larger or smaller number of web layers are formed on the belt 15 in the vertical direction. The number of layers is selected according to the required panel properties of the final product, e.g. weight, compressive strength, etc. The number of layers also depends on the fiber formulation, ie the individual fiber processing stages between the fiber production unit and the curing oven 25. Usually 2 to 40 to 50 layers are deposited on the collecting belt 15.

The deposition of the primary fleece 26 with the aid of the pendulum belt 13 not only provides a good transverse distribution of the fiber material on the collecting belt 15, but also contributes to a uniform fiber orientation and a certain homogenization. The fiber orientation can also be influenced in a controlled manner by changing the direction of the pendulum movement.

The deposited web is subjected to pre-compression in the pre-compression stage 17. The pre-compression is usually carried out in such a way that the web can be clamped by the rollers of the first conveyor pair (required nominal thickness plus a maximum of about 40% of the roll diameter). A certain amount of deflection of the web after pre-compression is desirable so that, on entering the compression unit, sufficient adhesion is obtained between the web and the rollers to obtain the required reorientation of the fibers. Since for products with a density of less than about 80 to 90 kg/m³ the expansion forces prevailing in the web during longitudinal compression are much lower, a moderate thickness compression in addition to the longitudinal compression is usually necessary in the manufacture of these products in order to set the required tension and to avoid undesirable folding on the web surface.

In the case of doubling, i.e. when the primary web is laid down in layers, the web surfaces have visible steps to varying degrees. These steps can be at least partially compensated for in the pre-compression stage 17 by driving the upper belt 29 at a slightly higher speed than would be necessary for further transport.

The partially smoothed web can be subjected to further smoothing in the optimization unit 19. For this purpose, for example, the first and second conveyor pairs can be arranged so that they are out of alignment. It is also possible for every other conveyor pair to be arranged out of alignment. This out-of-alignment arrangement subjects the transported web 20 to a bend or a transverse deflection, which can cause the web surfaces to be smoothed. The smoothing effect can be increased if the second conveyor pair runs somewhat slower than the first.

Preferably, a longitudinal compression of 2:1 to 6:1 (corresponding to the peripheral speeds of the first and last conveyor pairs 31 and 37) is effected in the compression unit 19 essentially with a roller spacing corresponding to the nominal thickness of the board to be produced (i.e., compaction by longitudinal compression without thickness compression). However, for lighter products, longitudinal compression together with simultaneous moderate thickness compression may be advantageous. For a single speed constriction, each of the two conveyor pairs 31, 33 and 35, 37 may be driven jointly by one drive.

Although conveyor belts can be used for compression, rollers are preferred because the tendency for folding at the web surfaces is relatively low, even when significant longitudinal compression occurs. The web can be compressed considerably with rollers 39 without noticeable folding at the web surface in the longitudinal direction. One possible explanation for this is that only a There is a slight adhesion between the rollers and the fleece. The rollers also promote the reorientation of the fibers, as the fleece can expand slightly between the rollers in any case, but without wrinkles.

This results in a good compaction of the fibre felt inside and on the surface.

In the multi-layer unit 21, the compressed fleece can be divided into two or more webs 43, 45. It is also possible to omit the multi-layer unit or to arrange it outside the conveyor path and to feed the fleece with the optimized fiber structure directly into the curing oven.

The fleece 20 is separated by a band saw or a band knife in a manner known per se. The upper web 45 with the optimized fiber structure is then subjected to compression in the thickness and length direction. As a result, the fibers of the upper layer 45 are further compressed by compression in the thickness direction and then in the length direction. The web 45' compressed in thickness is then returned to the continuously moving lower web 43.

The compressed fleece 43, 45', in particular the web 43 under tension, is guided between the compression stage 19 and the curing oven 25 by the conveyors 47, 49, 59, 61, 63, 65, e.g. belts, chains or roller systems, preferably conveyor belts, in order to prevent any breakouts or bulges.

In the curing oven 25, the binding agent in the fleece is cured. The binding agent is cured at temperatures between 180 and 300°C, preferably at about 200 to 250°C. The binding agent also ensures a firm bond between the two webs 43, 45' with low and high bulk density.

To improve the adhesion of the webs 43, 45', their contact points can be provided with a solid or liquid adhesive (dosing device 57) in the multi-layer unit before they are combined.

Alternatively or additionally, the bonds between the two webs 43 and 45' can be improved if the webs are slightly contracted prior to the curing oven 25, preferably in a ratio of 1.1:1 to 2:1. Depending on the degree of contraction, this can result in some wrinkles in the webs. The contraction results in increased contact surfaces and the adhesion/felting of the webs can be improved in this way.

With the device according to the invention described above, the fleece or felt is preferably compressed in one step in the longitudinal direction. Alternatively, the device can also be operated in such a way that a plurality of compression zones or a continuous compression zone are formed during the compression.

example 1

Panel type single layer

Fibre material rock wool

Plate thickness 100 mm

Bulk density about 90 kg/m³

Binder modified phenolic resin

Average fibre length about 3 to 4 mm

Average fiber diameter about 3 to 4 um

Pre-compression to approximately nominal thickness

Longitudinal compression 3 : 1

Compressive strength at 10%

Deflection 0.035 N/mm²

Peel strength 0.020 N/mm²

(delamination)

Example 2

Plate type two-layer

Fibre material rock wool

Plate thickness 100 mm

Thick outer layer about 20 mm

Substrate thickness about 80 mm

Average density about 90 kg/m³

Density outer layer 155 kg/m³

Bulk density substrate 75 kg/m³

Binder modified phenolic resin

Average fiber length about 0.5 to 10 mm

Average fiber diameter 3 to 6 um

Pre-compression to approximately 1.5 times nominal thickness

Thickness compression 1.8 : 1 to 1.1 : 1

Longitudinal compression 3 : 1

Compressive strength at 10%

Deflection 0.025 to 0.030 N/mm²

Peel strength 0.013 to 0.018 N/mm²

(delamination)

Example 3

Plate type two-layer

Fibre material rock wool

Plate thickness 100 mm

Thick outer layer about 20 nm

Substrate thickness about 80 mm

Average density about 90 kg/m³

Density outer layer 155 kg/m³

Bulk density substrate 75 kg/m³

Binder modified phenolic resin

Average fibre length about 3 to 4 mm

Average fiber diameter 3 to 4 um

Pre-compression to approximately 1.8 to 1.5 times nominal thickness Thickness compression 1.5:1 to 1:1

Longitudinal compression 3 : 1

Compressive strength at 10%

Deflection 0.025 to 0.030 N/mm²

Peel strength 0.013 to 0.018 N/mm²

(delamination)

Diameter of the rollers used 80 mm

Compared to panels without optimized fiber structure and density, the weight of panels produced by the new process can be reduced by up to 25 to 40% with otherwise essentially identical mechanical properties. The tensile strength perpendicular to the plane of the panel is greatly improved, which results from the highly structured fracture zones (Fig. 11b and 11c).

Products according to the invention can be used for all conventional purposes of man-made fibres, e.g. for panels, sheets used for thermal insulation, fire resistance and fire protection or sound insulation or sound absorption or in a suitable form in horticulture as a growing medium.

Claims (38)

1. Continuous process for producing a bonded mineral fiber board with a thickness t from a fleece with a thickness of more than 2 t, comprising compressing the fleece in the depth direction essentially without simultaneous compression in the longitudinal direction to a first thickness and a weight w per unit area, subsequently compressing the web in the longitudinal direction, whereby the web is forced to a second thickness, and thereby producing a longitudinally compressed web, transporting the longitudinally compressed web to a binding station (25) and binding the web in the binding station (25) to form a bonded mineral fiber board, characterized in that the first thickness is in the range of 0.8 to 1.5 t, preferably between 0.9 and 1.3 t, the second thickness is in the range between 1 and 1.3 t, preferably 1 to 1.1 t, the compression in the longitudinal direction is carried out continuously or in one or more stages essentially without folding the web and produces a longitudinally compressed web with a weight per unit area of 2 to 10 w and the breaking of the fleece during transport between the longitudinal compression and the binding station is prevented. 2. Method according to claim 1, characterized in that the compression of the fleece in the longitudinal direction is effected in one step. 3. A method according to claim 1 or claim 2, in which the longitudinally compressed web and the bonded sheet have a weight per unit area of 2 to 6 w, preferably 2.5 to 4 w. 4. A method according to any one of claims 1 to 3, in which the longitudinal compression is effected by feeding the web by means of a first conveyor (30) to a second conveyor (32), wherein the second conveyor (32) is driven at a lower speed than the first conveyor and where each conveyor (30, 32) comprises two opposing roller groups (30', 30") each comprising at least two spaced rollers (39). 5. Method according to claim 4, in which the opposing roller groups of at least one conveyor device (30, 32; 31, 33, 35, 37) are driven at different speeds. 6. A method according to any preceding claim, in which break-out of the web during transport of the web between the longitudinal compression and the bonding station is prevented by a restricting device, the restricting device comprising a belt, rollers or other guides which prevent significant deviation from the desired path. 7. Method according to claim 4, in which the break-out of the web during transport between the compression in the longitudinal direction and the binding station is prevented by expanding the web by another conveyor after the second conveyor device. 8. A method according to any preceding claim, in which the web after being longitudinally compressed is stretched longitudinally. 9. A method according to any preceding claim, in which the web is formed from artificial glassy fibers, preferably rockwool fibers, and contains uncured binder and the binder is cured by heating in the bonding station. 10. A method according to any preceding claim, in which the web is formed by cross-laying. 11. A method according to any preceding claim, in which the longitudinally compressed web is divided into two or more sub-webs parallel to the major surfaces prior to the bonding station and each sub-web is constrained against breakaway on its way towards the bonding station and at least one of the webs is compressed in the thickness direction and/or longitudinal direction and the sub-webs are then combined and bonded in the bonding station. 12. A method according to claim 11, in which the contact surfaces are provided with a binder prior to joining. 13. A method according to claim 11 or claim 12, characterized in that the combined webs are compressed in the longitudinal direction before the binding station. 14. A process for the continuous production of a bonded mineral fibre board, in which a fibre felt is pre-compressed in the thickness direction to a thickness of 1 to 3 times the final product and is then subjected to compression in the longitudinal direction by means of at least two conveyor pairs driven at different speeds to produce a longitudinally compressed felt and is then bound in a binding station (25) to give a bonded mineral fibre board, characterized in that the thickness of the felt in the step the compression in the longitudinal direction or before the binding station is approximately between 0.9 and 1.3 times the thickness of the final product, the compression in the longitudinal direction is effected substantially without compression in thickness, the compression in the longitudinal direction is effected to approximately 0.5 to 0.1 times the original length, the compression is effected in a continuous compression zone and the felt is held to prevent breakout between the unit for the compression in the longitudinal direction (19, 19') and the binding station (25). 15. A method according to claim 14, characterized in that the thickness of the felt in the zone of longitudinal compression is substantially the same as the nominal thickness of the final product. 16. Device suitable for carrying out the method according to claim 1 and comprising a conveyor device (19, 40; 19, 23) for transporting the fleece to a binding station (25), a device (17) for compressing the thickness of the fleece, a device for compressing the fleece in the longitudinal direction (19; 19') which follows the device for compressing the thickness (17), a binding station (25) for binding the fleece compressed in the longitudinal direction, characterized in that the device includes a device (59, 61; 40, 42) for preventing the fleece from breaking out between the device for compressing in the longitudinal direction and the binding station (25) and the device for compressing in the longitudinal direction comprises at least two roller conveyors (30, 32) which are arranged one after the other in the conveying direction, each roller conveyor (30, 32) comprising two opposite groups of at least two rollers (39), the opposite roller groups form a conveying path (F) for the fleece, a drive device for driving the rollers (39) of each group at substantially the same peripheral speed, a device for controlling the peripheral speed of the rollers (39, 39') of each individual group independently of the speed of the rollers in each other group and a device for adjusting the distance between the opposing roller groups (30', 30';32',32") of the conveyors (30, 32) independently of the distance between the rollers in other conveyors. 17. Device according to claim 16, characterized in that two roller conveyors (30, 32) are provided, which are arranged one after the other in the conveying direction (F). 18. Device according to claim 16 or claim 17, characterized in that each roller group comprises 2 to 8 rollers, preferably 4 to 6 consecutive rollers. 19. Device according to any one of claims 16 to 18, characterized in that at least one of the roller conveyors (30, 32) has a device for inclining the opposing roller groups relative to one another, e.g. in order to produce a nonwoven web tapering in the conveying direction. 20. Device according to any one of claims 16 to 19, characterized in that the roller diameter and the distance between the rollers (39) in the conveying direction are such that any breaking or folding of the fleece is substantially prevented. 21. Device according to any one of claims 16 to 20, characterized in that the roller diameter is less than about 18 cm and preferably lies between about 60 and 160 mm and particularly preferably between 80 and 120 mm. 22. Device according to any one of claims 16 to 20, characterized in that at least the first conveyor (30) comprises a device for Adjustment of the position of the conveying path through said conveyor relative to the position of the conveying path through the following conveyor(s) (32). 23. Device according to any one of claims 16 to 22, characterized in that the conveyors (30, 32) are arranged horizontally. 24. Device according to any one of claims 16 to 22, characterized in that a separating device (41) for separating the fleece into two or more sub-webs is provided between the roller conveyors (31, 33, 35, 37) and the binding station (25), at least one compression stage (53, 54) is provided for the thickness and/or lengthwise compression of at least one sub-web, and conveyors (59, 61, 63, 65) are provided to hold the compressed fleece and the sub-webs on the way to the binding station (25) in order to prevent any deformation in the direction of the thickness or breakout. 25. Device according to claim 24, characterized in that the separating device (41) and at least the conveyor (47) are adjustable in terms of the height, so that the device can optionally be used for the production of single-layer or multi-layer products. 26. Device according to claims 24 or 25, characterized in that a device (57) is provided for the metered addition of a binding agent for the mutual contact surfaces of the lower webs. 27. Device according to any one of claims 16 to 26, characterized in that a device for driving the conveyor devices between the compression stage and the binding station and in the binding station is provided independently of one another. 28. Method according to any one of claims 1 to 15, comprising feeding the longitudinally compressed web to a separating device (41) before transport to the binding station, separating the web with the aid of the separating device (41) into two or more sub-webs (43, 45), compressing at least one sub-web (45) in the thickness direction, subsequently combining the sub-webs (43, 45') and transporting them to the binding station (25) in which the web is bound, whereby the breaking out of the sub-webs (43, 45) under tension between the compression unit (19) and the binding station (25) is prevented by a restricting device (49, 50, 51, 59, 61, 63, 65). 29. Method according to claim 28, characterized in that at least the one bottom web (45) compressed in terms of thickness is compressed in the longitudinal direction. 30. Method according to claim 28 or claim 29, characterized in that the contact surfaces of the lower webs (44, 45) are provided with a binding agent before joining. 31. A method according to any one of claims 28 to 30, characterized in that the combined webs (44, 45') are compressed longitudinally prior to binding. 32. Method according to any one of claims 28 to 31, characterized in that the separating device (41) is continuously cleaned. 33. Device according to any one of claims 16 to 27, which includes a first transport device (19) for transporting the web to a separating device (41), a separating device (41) for separating the web into two or more sub-webs (43, 45), a device for compressing at least one sub-web (45) in the direction of the thickness, a second Transport device (23) for subsequently combining the lower webs (43, 45') and for transporting them to the binding station (25) in which the fleece is bound, wherein the first transport device (19) comprises the device for compression in the longitudinal direction and comprises at least two conveyor pairs (31, 33, 35, 37) which are arranged one after the other in the conveying direction, and a device (49, 50, 51, 59, 61, 63, 65) is provided to prevent the breakage of the lower webs (43, 45) under tension between the compression unit (19) and the binding station (25). 34. Device according to claim 33, characterized in that a device (57) is provided for providing the lower webs with a binding agent before re-joining. 35. Device according to claim 33 or claim 34, characterized in that the separating device (41) consists of a band knife or a band saw. 36. Device according to any one of claims 33 to 35, characterized in that a cleaning device is provided for the continuous or discontinuous cleaning of the band knife or the band saw. 37. Device according to any one of claims 33 to 36, characterized in that at least the separating device (41) and the subsequent holding-down device (49) are vertically adjustable in the region of the multi-layer unit (21). 38. Device according to any one of claims 33 to 37, characterized in that for the production of substantially folded products, the distance between the opposing conveyors of a conveyor pair (31, 33, 35) can be adjusted to approximately 0.5 to 0.1 times the distance between the conveyors of the following conveyor pair (33, 35, 37) and the conveyor path defined by the two conveyor pairs is substantially aligned.