FI85034C - Method and apparatus for treating a mineral fiber web - Google Patents

Description

The present invention relates to a method and apparatus for treating a mineral fiber web for reorienting the fibers in the web, by successively changing the speed of the web during its transport through a conveying device, wherein the velocity change of the web is performed by bringing the web into contact with at least two longitudinally arranged elements in the longitudinal direction of the web.

Mineral wool products of glass wool, stone wool and slag gold type, are the most well known and used products for heat insulation as well as acoustic insulation.

These products are generally manufactured such that the raw material is melted, the mineral melt is converted into fibers e.g. by passing it into a spinning device, which can consist of a plurality of rotating wheels, the formed fibers are transported with an air stream from the spinning device and collected on a conveyor in the form of a fibrous web. The collection can take place either so that the fibers are collected on the conveyor to a web with the desired final thickness, or by forming a so-called. primary web by collecting a thin layer of fibers and then, e.g. by means of a shuttle conveyor, fold this primary web into a secondary web of the desired thickness.

At some point in the preparation of the web, it is impregnated with a suitable binder, e.g. a resin which is cured at a final stage of the web treatment by heat, e.g. in a hardening furnace, wherein the fibers are fixed to each other to form a stable, continuous web of the desired density and thickness. Next, the web is cut to the desired format, either as disc products or roll products, which are then packaged or further processed.

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In collecting the fibers from the spinning device, either in the form of a primary web, or in its final thickness, the fibers settle on the conveyor essentially in a plane which is parallel to the conveyor, ie. only a small amount of the fibers take a direction more or less angular to the plane of the conveyor. This phenomenon is advantageous in some applications, as such products exhibit good elastic properties, but are of great disadvantage in others. In particular, this structure of the web results in dS-strength properties in a direction perpendicular to the plane of the web, so such products cannot be used in structures subjected to excessive mechanical stress, e.g. in floors, or in roofs that are loaded.

One way to achieve sufficient mechanical strength in the direction of the web's plane is to increase the web's volume weight, ie. tSt-hot, which can be done by increasing the amount of fiber, or in some cases the amount of binder. However, the manufacturing costs are directly proportional to the weight of the fiber, which is why an increase in the pour strength through an increase in the fiber volume may in some cases be economically unacceptable.

The increase in pouring strength in a direction perpendicular to the web's path can also be achieved by changing the direction of the fibers in the web so that a greater part of them is brought in a direction that deviates from the web's path. This can be achieved in several ways.

One can, for example, Cut the web into strips whose width is the same as the desired mat thickness. The strips are turned 90 ° and glued back together into a so-called. lamella mat, whose fiber direction to the predominant part is perpendicular to the main surfaces of the mat. An example of this process set is given in EP A 0 000 378. However, such lamella products are next manufactured in a special finishing or processing line with subsequent supplementary costs.

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It is also possible to make a mat with virtually the same properties as the laminate mat without cutting and gluing, by corrugating the fiber web ρέ appropriately, compressing the corrugated web to the desired density and curing it. Such a process is described e.g. in U.S. Patent No. US 1,656,828 (Fig. 6). Also in this product the fiber direction is predominantly perpendicular to the plane of the web. However, the fold formation on the surfaces of the web presents disadvantages. It lowers the flexural strength in the longitudinal direction of the track, while at the same time folds are disruptive to the disc which the seed is to be used as acoustic disc. Even the slat products as the corrugated products exhibit up to 10% poorer thermal insulation capacity compared to conventional sheet products.

A third way of changing the main fiber direction in the web is described in DE A 16 35 620. According to this method, the conveying speed of the web between two subsequent conveyors is slowed down by giving the lower conveyor speed seen in the transport direction lower than the front one. This braking results in longitudinal compression with a reorientation of the fibers within the web, with no creasing on the surface. The method achieves good results with regard to the final product bed's mechanical and insulating properties on the degree of compression, ie. the velocity decrease of the web during treatment is kept below about 30%. If the compression rate is higher, folding begins to build up on the surface of the web. However, this disadvantage can easily be avoided if the procedure is repeated, ie several compression steps are performed one after the other, which is also proposed in FI patent application 84 2734.

Thus, in the above-described method, the compression takes place in a zone of the web which lies in front of the rear, slower: conveyor, and which extends rectilinear over the width of the web. within this zone, the reorientation of the fibers takes place fairly uncontrolled and is controlled only by the orifice of the rear conveyor, which constitutes the braking plane of the web, and by any guide plates arranged above and below the male, which plaque prevents the web from swelling up. more than desired. These plaques do not participate in the actual reorientation of the fibers. Also, no significant compression takes place within the transport device itself, but it acts almost as a stabilization zone after the shock-like compression. If a higher degree of compression is desired, a space-intensive system is needed, which, after all, does not allow any more accurate control over the treatment process.

The present invention has as its object to overcome the disadvantages associated with the known devices, in particular with the uncontrolled treatment of the web in a few powerful single station operating across the width of the web. Namely, in the method and apparatus of the invention, there is a controlled and fine-structured re-orientation of the fibers in the web as a result of a substantially continuous controlled rate change of the web, without folding and in a work step that can be easily incorporated into existing production lines. .

This is achieved by the method according to the invention, characterized in that the areas of operation of the elements mentioned in the preamble of claim 1 overlap each other.

The velocity change of the web over all elements is preferably negative, i.e. the exit velocity of the web from the last element is lower than its velocity before the first element.

In a further preferred embodiment, the elements are so formed and arranged relative to each other that the boundary or boundary zone where an element's impact on the web is greater than that of the adjacent element is constituted by a substantially road-shaped line extending over the width of the web.

Said element is preferably a shaft pair extending across the web, with a shaft on each side of the web rotating towards each other. The shafts have means which come into contact with the web and affect the web's speed of transmission, ie. Depending on the rotational speed of the shafts in relation to the conveying speed of the web, they may act as the slowing or accelerating pS web, with a reorientation of the fibers as a result. The shafts are arranged so that when the web is passed through a plurality of successively arranged elements, the areas of action against the web of two consecutively arranged elements overlap or engage one another. It is this overlap of the operating ranges of the elements, ie. the continuous impact of the elements on the web, which is believed to give rise to the advantageous end result, as opposed to the shock-like shock treatment of the prior art.

In order to better understand the invention, it is conceivable that the portion of the web under treatment is divided into a number of treatment or reorientation zones extending over the width of the web. A treatment zone can be defined as an area in which an element has a greater influence on the path or path than the adjacent element (s). The web forward speed of one element is entirely determined by said element, but the influence on the speed of transmission then gradually transitions to the next element. At some point between these elements, the velocity is more determined by one element than the other. These more or less theoretical points define a line which is not necessarily straight and extends across the path. This line, in turn, defines the boundary between two treatment zones.

Since, in the treatment according to the invention, each element's area of operation overlaps or intervenes in the area of adjacent elements, each cross-section of the web is always in one treatment zone, where it is exposed and affected by at least one element. SS, the above-mentioned fine-structured and "gentle" reorientation of the fibers in the web is obtained.

By designing the elements such that they form discrete contact areas with the web in a direction across the web, their effect on the web is directed not only in the direction of movement of the web, but also in a direction more or less perpendicular to the direction of movement of the web, ie. in one direction Sver width. As these contact areas are arranged laterally offset relative to each other in the direction of transport of the web, the boundary between the operating areas of the two elements will form a substantially road-shaped line, whereby further advantages are achieved. If the velocity of the web at two successive contact areas 3 is different, the shear forces in the web which Sr directed the front and rear, with Sven sideways, increase in a direction towards the edges of the web. This results in smoother machining of the fiber web in all its dimensions and thus gives better flexural strength to the product than what has been possible with the previously known solutions. By varying the size of the contact areas, each other 13 g, the compressive force of the elements against the web and the size of the web speed change, the treatment can be controlled accurately and in accordance with the desired result.

Preferably, the web is subjected to a treatment over a plurality, e.g. 4-12 element. According to one embodiment of the invention, the web is subjected to a speed decrease over the entire length of the conveyor device, which reduction is preferably continuous and uniform, ie. there is an equal reduction in speed from element to element, as preferred

about 10-20%. However, the speed change does not have to be equal, but it can advantageously be different at different stages of the treatment. Thus, the rate decrease from element to element may be smaller at the beginning and greater at the end of the treatment, or the rate difference between two successive zones may be substantially greater than between other zones. Such a more powerful treatment is advantageous there in the latter part of the device. However, it is also possible to increase the velocity of the web in any or any of the treatment zones, provided that the treatment leads to a final product with unpainted fibers.

An acceptable product, without folding, is obtained by the method of the invention if the web is subjected to a treatment which results in varying degrees of compression, but preferably a compression ratio of about 2: 1 to 10: 1, especially 3: 1 to 6: 1, which corresponds to a speed reduction as a percentage of about 50-90%, especially about 70-80%.

In a preferred embodiment, the web is pre-compacted perpendicular to the main plane of the web prior to the treatment to a thickness less than the web thickness after the treatment. By pre-compressing the web, for example to about 70% of the final thickness, and allowing it to expand during the treatment, a greater compression can be performed without causing disparities in the surface layer of the web and, respectively. inner layer, ie the emergence of a so-called. arrow shaped fiber structure of a cross section through the product. This has become a further problem with large compression according to the known procedures.

The invention also relates to a device for carrying out the process. The device has in its simplest form a conveying device comprising two conveyors arranged against each other, between which the fiber web is moved, each conveyor comprising at least two rotational shafts driven at different rotational speeds, forming between themselves shaft pairs and the shafts having means intended to be brought in contact with the surface of the web facing the respective conveyor, and the axis of action of the shaft pair overlap.

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The shafts of a conveyor can be driven at different rotational speeds, while a shaft pair consisting of the shafts arranged against each other in different conveyors is always driven at the same speed, but in the opposite direction.

Preferably, the shaft carries a plurality of interposed members on the shaft, which on one shaft are directed towards and project into the interstices between the members on an adjacent shaft. According to one embodiment, the members of a shaft in one conveyor form a nip for the web with corresponding members of a shaft of the other conveyor, but they may also be directed to the spaces between the members of the latter shaft.

Preferably, the conveying device contains from 4 to 12 shafts in each roller conveyor thus forming equal numbers of shaft pairs. The organs coming into contact with the web may be given any suitable design, for example. the shape of blades, rivets, discs, flanges or the like, or they may be formed as spaced apart across the width of the web, extending short endless conveyor belts longitudinally, and may exhibit varying friction-increasing formations, e.g. studs or the like.

In order to enable an adjustment of the device for making products of different types, it is advantageous for the shafts to be provided with means for independent variation of the rotational speed of the shafts. The design of the drive devices is well known to those skilled in the art.

The conveyors may further be provided with means known per se for adjusting the distance and / or the mutual inclination between the conveyors. In such cases, the treatment can be carried out during simultaneous thickness compression or expansion of the web, the reorientation conditions of the fibers can be further modified and the treatment thereby adapted for very different product types. The distance and / or the degree of slope can be varied along the transport device's ISngd.

In order to further illustrate the invention, reference is made in the following to the accompanying drawing, in which: Figure 1 shows schematically a device for producing a fiber web, which includes a device for processing the web according to the invention; Figure 2 schematically illustrates the principle of an embodiment of cooperating shafts in a roller conveyor, in plan view, figure 3a shows the embodiment according to figure 2, seen in the direction of transport of the web, and figure 3b the same embodiment seen from the side, figure 4 shows an alternative embodiment of the means for contact with the web, and figures 5a - 5d show different velocity profiles of the web during its transport through the conveyor.

Figure 1 shows schematically the treatment of a fiber web, which in the form of a primary web 1 is guided from a non-displayed spinning device to a pendulum conveyor 2 and folded into a secondary web 3 of the desired thickness. This secondary web 3 is then led between two rollers 4, 4 ', which effect a pre-compression of the web 3, in a direction perpendicular to the plane of the web. In the nip 4, 4 ', the web is compressed to a thickness less than the web thickness after treatment, and suitably to about 70% of the web's final thickness. Thereafter, the path is preferably passed over control means 5, 6, 7 into a transport device for processing according to the invention, which device as a whole is designated by the reference numeral 8. The transducer 8 5 034 gate device 8 has an upper and a lower conveyor 9 and 9 respectively. 10, each of which in the present embodiment has twelve rollers in the form of camshafts, two opposing camshafts 11 and 11 ', 12 and 12', etc. forming a camshaft pair which together limit nip 11a, 12a etc. for the track. According to a preferred embodiment, the speed of the conveyors decreases in the direction of movement of the web by the camshaft pair having a gradually decreasing rotational speed.

A suitable rate decrease between two successive axes is 10-20%. In the present case, e.g. the two first shaft pairs have the same rotational speed as the speed of the conveyor prior to the conveying device, while the speed is then incrementally reduced in the manner of subsequent shafts and the last few shafts of the device can be given the same speed as the conveyor in the hardening furnace, as shown in the figure with reference numeral 15. The final product is cured and fixed in the furnace.

Figure 2 shows schematically how the camshafts can be designed and cooperate in a conveyor, seen in plan view. The direction of movement of the web between the axes is indicated by a right arrow. Thus, in the present embodiment, each cam disc 16 of a cam shaft projects into the space between two cam disks 16 'and 16 "of the adjacent cam shaft. In the present embodiment, the cam shafts have a center spacing (a) which is about 70% of the cam shaft disc diameter, The width (b) of the center is about 30% of the center distance, and the space (c) is about 40 - 50% of the center distance. In the figure, the nip 17 also indicates the nip 17 for some neighboring cam disks. substantially rectilinear contact areas with a limited extent substantially in the transverse direction of the web, two successive camshaft types giving rise to contact areas in zigzag pattern across the width of the web.

In Figures 3a and 3b the arrangement according to Figure 2 is shown partly in the direction of movement of the web (3a) and seen from page 85034 dan (3b) respectively. In Fig. 3a, the solid lines show the embodiment of the invention, in which the cam discs 16 1 each conveyor are directed at each other and form a nip 17. In the same Fig. 3a an alternate embodiment is shown, where the cam discs in each conveyor not facing each other, but a cam disk in one conveyor staring at a space between the cam discs in the other conveyor. Figure 3b shows the arrangement of Figure 2 seen from the side.

A further embodiment of the means is given in Figure 4, which shows a shaft mounted disc 16 whose pS has its outer periphery having a plurality of flanges 18 distributed around the circumference.

In Figures 5a - 5d, alternative embodiments of the web speed profile during the treatment according to the invention are shown. Figure 5a shows the case where the web is subjected to uniform speed reduction over all elements of the device. Figure 5b shows again the case where the rate decrease is smaller at the beginning of the treatment, and greater towards the end, while Figure 5c shows the case where the most rapid change in speed occurs in the middle of the treatment. Finally, Figure 5d refers to the case where the velocity of the web is also allowed to increase at one or more elements.

Claims (14)

A method of treating a mineral fiber web for re-orienting the fibers in the web, by successively changing the web's speed, wherein the rate change of the web is effected by contacting the web with at least two elements, arranged in the longitudinal direction of the web (11, 11). 12 and 12, respectively, characterized in that the areas of action of the element against the web overlap. A method according to claim 1, characterized in that the velocity of the web is reduced such that the ratio between the velocities at the beginning and the end of the treatment is about 2: 1 - about 10: 1, preferably about 3: 1 - about 6: 1. . 3. A method according to claim 1 or 2, characterized in that the boundary at which an element's impact on the web becomes greater than that of the adjacent element is formed by a substantially road-shaped line extending over the width of the web. 4. A method according to claim 3, characterized in that the contact between the web and one of said elements is limited to a plurality of separate contact areas arranged across the web, the contact areas of the web with successively arranged elements being laterally displaced relative to each other. . Method according to any of the preceding claims, characterized in that the thickness of the web is successively changed during the treatment. 6. A method according to any one of the preceding claims, characterized in that the velocity of the web is gradually reduced during the treatment, whereby the decrease in velocity between two successive elements is 10-20%. i3 85034 7. Apparatus for processing a mineral fiber web for re-orienting the fibers in the web, by changing the speed of the web during its transport through a conveying device, characterized in that the conveying device (8) comprises two conveyors (9, 10 arranged against each other). ), between which the fiber web (3) is moved, each conveyor comprising at least two shafts (11, 12 and 11 ', 12') driven at different rotational speeds, respectively, which form shaft pairs (11, 11 'and 12, respectively). , 12 '), and the shafts have means (16) intended to be brought into contact with the surface of the web facing the respective conveyor, and the areas of operation of the shaft overlap. 8. Apparatus according to claim 7, characterized in that the shafts carry a plurality of spaced apart means, the means (16) on one axis being directed to the spacing between the means (16 ', 16 ") in an adjacent shaft. in the same conveyor and pushes into the same. Device according to claim 8, characterized in that the means (16) on one shaft (11) in one conveyor are directed to the corresponding means ρέ corresponding to the shaft (11 ') in the other conveyor to form a nip for the web. . 10. Device according to claim 8, characterized in that the means (16) in one shaft (1 1) of one conveyor are directed to the spaces between corresponding means in the corresponding shaft (11 ') of the other conveyor. Device according to any of claims 7-10, characterized in that the means for contact with the web are made up of nails, vanes, cam discs, endless. conveyor belts or the like, which may be provided with friction-increasing formations. i4 85034 Device according to any of claims 7-11, characterized in that the shafts in each conveyor Mr are provided with means for varying the rotational speed of the shafts independently of one another. Device according to any of claims 7-12, characterized in that the conveyors are provided with means for adjusting the mutual distance and / or the mutual inclination between the conveyors, which means allow a variation of the distance and / or the mutual inclination along that of the conveyor device. length. Device according to any of claims 7-13, characterized in that it has a device (4, 4 ') before the transport device (8) for compressing the web to a thickness less than the web thickness after the treatment. is 85034