FI61223C - FOER FARANDE OCH APPARAT FOER BILDANDE AV ETT BANFORMIGT MATERIAL BESTAOENDE AV LOESA FIBER ELLER PARTIKLAR - Google Patents

Description

© FINLAND —FINLAND patent publication — patentskrift 6122 3 © Kv.lk?/lnt.CI.3 D 21 H 5/26 ® ® Patent application - Patentansökning J62b2k @ Application date - Ansokningsdag 2U.O8.76 • ® Start date - Giltighetsdag 2U.O8. 76 © Released to the public - Blivit offentlig 28.02.77 @ Date of display and publication—

Ansökan utlagd och utl.skriften publicerad 26.02.82

National Board of Patents and Registration © Patent granted - Patent meddelat 10.06.82

Patent and registration authorities

Requested privilege - Begärd priority 27 · 0ο · 75

England-England (GB) 35U29 / 75 (73) Scan-Web I / S, Bryggervej 21, 82U0 Risskov, Denmark-Danmark (DK) (72) Torsten Bengt Persson, Maarslet, Denmark-Danmark (DK) (7U) Letizinger The present invention relates to a process for the production of e.g. paper or nonwoven textiles and nonwoven fabrics. The present invention relates to a process used in the manufacture of e.g. paper or nonwoven fabrics and a process for forming a web-like material consisting of loose fibers or particles. the type of which appears from the preamble of claim 1.

British Patent Specification No. 1,207,556 describes a procedure and apparatus of this type for carrying out the method. The fibrous material is filled into a round, cylindrical basin with a flat, perforated bottom positioned parallel and tightly at the underlying moving carrier belt, which is a wire. The substance is agitated near the perforated bottom by means of a mixing device comprising two vertical rotor shafts mounted in a planetary gear system above the basin and having radial, vertically oriented mixing vanes rotated around the material layers at just below the perforated bottom. base. Underneath the basin and the drawn wire, a suction box is placed which absorbs the flow of air through the substance in the basin and the perforated bottom and wire, whereby the fibers dispersed near the bottom are drawn out and lowered onto the drawn wire in a relatively even layer. The wire transfers the layer further to a binding or tempering station, where the layer is made into a nonwoven web material that can be used for many purposes.

By stirring the fibrous material, the aim is to ensure that the fibers are kept mixed with air and that they are accordingly rearranged relative to the other fibers, so that they can sooner or later pass through the small holes in the perforated base together with the intake air. The degree of fiber rearrangement is greatest where the speed of the wing edges is greatest, i. effective confusion is achieved in the annular region at the outer edges of the wings. However, due to the centrifugal forces that tend to force the substance out of this range, it happens that a higher blade speed only increases the power of the plant to a certain point, after which the power decreases, and the maximum achievable power is not as high as would be desirable.

According to another known procedure, the fibrous material is introduced into a cylindrical space between a horizontal roll and a perforated jacket, the roll having a large number of radial needles which disintegrate and rearrange the fibrous material. However, the fibrous material tends to move rapidly through said space along the surface of the roll, whereby the speed of the needles relative to the material does not become nearly as high as the absolute speed of the needles, reducing the need for the needles to reposition the fibers.

The object of the invention is to develop a procedure in which a high extraction efficiency is achieved in an easy manner.

According to the invention, this is achieved by agitating the substance in the container by whipping it just inside said perforated wall part. The word "whip" used in this and the following description and claims denotes an operation in which a relatively small body is moved rapidly through a mass of material to be whipped, the proportions of which disintegrates the shape of the mass in the body without moving it. movement per se to a substantial extent in the direction of movement so that the components of the mass become rapidly separated and moved along the trajectory of the body. When a dry, fibrous or otherwise loose material is whipped in this way in the air, the fibers or particles are kept fluid and the whipping causes a large repositioning of the fibers or particles without forcing them to move with the whip body, allowing the 5 61223 fibers or particles to be immediately sucked into the perforated wall. through, which ensures high ejection power. The higher whipping speed mainly causes the fibers or particles to be reprocessed to a greater extent, whereby the spreading power increases correspondingly within wide limits.

In practice, it is difficult to spray the substance near all surfaces of the torn wall portions of the tank, but experiments have shown that very good results can be obtained by spraying in separated areas along the torn wall and forcing the substance to move relatively slowly from one whip area to the next. If the substance is first whipped, it will remain in its fluid form for some time, and if the whipping is repeated shortly thereafter by moving the substance to the next whip area along the torn wall, the particles or fibers in the whip flow can be immediately scattered through the perforations.

Said movement of the substance from one whip area to the next can be easily effected by means of the whip pieces themselves when they are moved in a uniform manner along the perforated wall, which causes a general, relatively slow movement of the substance along the wall. This movement may very well be as fast as the absolute speed, but it is much slower than the movement of the whips.

The invention further relates to a device for carrying out a procedure as defined in the claims and as described in more detail below.

Already in this context, it should be mentioned that a very important feature of the invention is the use of rotating whips, which rotate in a non-parallel plane with respect to the torn wall part, whereby the whips cause the substance to be thrown against the perforated wall, which contributes to it. that the fibers or particles penetrate the routed wall. Whips can be arranged to whip within fixed areas, and their fast-moving circumferential portions can pass very close to the torn wall area without having to move other parts that are moved more slowly just near the wall area, which could cause fiber accumulation due to relatively slow massaging or rolling; than in the episode.

The invention will now be described in more detail by way of example with reference to the drawing in which 4 61223 Fig. 1 shows a side view, partly in section, of a preferred device according to the invention, Fig. 2 shows a cross-sectional view of the device, Fig. 3 shows a detail of Figs. 1 and 2 from above; partly in section, Fig. 5 shows a modified detail, and Fig. 6 shows a perspective view of a modified device according to the invention * ·

Fig. 1 shows an elongate fiber distribution container, indicated by the general numeral 1, having two semicircular main portions 2, each with an upper semicircular portion 4 and a lower, frustoconical portion 6 with a semicircular base plate Θ. The main parts 2 are connected to the vertical side plates 10 between the upper cylindrical parts 4, and these parts 2-10 are made of non-perforated metal plate material. Mounted between the side plates 10 and the main portions 6 and 8 is a screen base indicated by the general numeral 12 which passes through fibers and air and has a U-shaped cross-section corresponding to the shape of the main portions 2, i.e. has a flat, horizontal bottom screen portion 14 and two outwardly and upwardly extending screen surfaces 16 . the container 1 is supported by columns 18 transversely fine-eyed, a horizontal carrier web above, which is referred to as the next loop of fabric 20, which is guided endlessly around rollers 22 and which is used for the non-operating position shown by displaying the direction of the arrow. A suction box 24 with an exhaust fan 26 is located under the screen base 12 and the wire 20 and supported by beams 19 connected to the columns 18. The bottom and side of the suction box are closed and have an upper opening 28 close to the wire 20 below it and sealed against it by sealing flanges 30. One side of the suction box has a horizontal sliding plate 32 with a curved edge portion 54 guiding the suction area, as described in more detail below. At the second main part 4 is placed a bracket 36 »which supports a motor 38 which, by means of a chain drive 40, drives four vertical shafts 42 running on bearings 44» mounted on transverse support parts 46 which in turn rest on the upper edges of the side plates 10. The shafts 42 are arranged in a row in the vertical plane of symmetry of the container and each is provided with three, directly opposite and radially mounted, flat and elongate pairs of rotor pieces 48, the length of which is adapted so that their outer circumferential portions pass through areas of short distance away from the inclined screen surfaces 16, 5 61223 and in addition the lower rotor pieces are located slightly above the bottom screen part 14. The lower rotor pieces are positioned so as to rotate side by side in a common, horizontal plane above the bottom screen portion 14, while the other rotor pieces are offset relative to each other and have a length that rotates in areas that are partially overlapping.

Along the parallel long sides, the container is provided with outer wall plates 50 which, together with the side plates 10, form flushing air passages 52 closed at the sides by plate portions 54. The wall plate 50 and plate portions 54 extend tightly down over the wire 20 and enclose a substantially three-sided sieve space. and between the wire 20, which space is protected against ambient air except for the upper opening of the purge air passage 52. The lower edge of the wall plates 50 is bent and thus forms an air barrier 56 through which the wire can pass with the fibrous layer laid on top of it, as will be explained below.

In use, the shafts 42 are rotated in the same direction, whereby the circumferential parts of the rotor bodies are moved by about 50 m / sec. speed. This speed is suitable, for example, for processing cellulose fibers, but it can be adapted to the desired product and is adjustable over a wide range. The air flow is provided through a screen base 12, a wire 20, a suction box and out through a suction fan 26. In the same way, air is sucked in through the purge air ducts 52. The disintegrated material, e.g., cellulosic pulp, is fed into the tank through the fiber spreading inlet 58 to approximately up to a level at the height of the upper rotor bodies and is agitated by rapidly rotating bodies 40 which then whip violently through the material. As the rotor bodies rotate in the same direction, the fibrous material is thrown against substantially opposite, inclined screen surfaces 16, the surface profile of the material having a shape substantially in line with the broken line in Figure 2. The material carried by the screen surfaces 16 is forced by the rotor bodies 48 to move along the respective surfaces in a relatively slow flow around the container, along its sides and ends. Those fibers which then pass through the areas of movement of the rotor bodies become strongly whipped and repositioned and remain in a fluid state until they arrive at the next whip area with said current. Thus, a stream of fibrous material is continuously passed over the outer edge portions of the screen plates 16 and the bottom screen portion 12, which can thus be immediately sucked through the screen base 12. Once the fibers have passed these screen surfaces, they follow with the intake air and are lowered onto a wire 20 which separates the fibers from the air and thus forms a loose web of fibrous material which is carried by means of the wire through the barrier 56 for solidification or the like.

, 61223 6

Some of the fibers come from e.g. due to static electricity being discharged inside the outer wall 50,54, but this is opposed by the flushing air flow which runs down the inner side of these walls when it is guided through the duct 52. Absorbing air in this way per wire also increases the tendency of any thinner areas of the wire to become filled due to their lower suction resistance, causing the floating fibers to be drawn more centrally than other areas of the wire to provide a desirable, even distribution of fibers on the wire. If the fibers are scattered more from the sieve parts opposite the areas through which the rotor bodies pass over a short distance, an effect is obtained against the consequent, uneven distribution of the fibers. It should be noted that the longest distance that the fibers travel from the screen surfaces to the wire is from the upper screen surface portions, i. from the areas where the circumferential parts of the rotor bodies have the highest rotational speed, i.e. from the areas where the fibers are most efficiently extended.

The flow of material inside the tank is reversed at each main part 2 and thrown around and upwards along the semicircular sides 6 towards the area of the cylindrical main part 4 from which the substance is directed downwards towards the longitudinal sides and bottom, etc. As the flow turns, any heavy particles, fiber bundles or other to the area above the conical portion at the circumference where they can be removed. For this purpose, a lateral outlet pipe 62 is used, the opening of which towards the container is a slit which is partially locked by means of a slidably mounted sheet metal plate 64 for adjusting the height of the slit and thus for controlling, for example, the number of foreign objects. The outlet pipe 62 can be connected to the tank in a known manner by means of recirculation means.

The rotor bodies 48 may have various shapes to provide their whipping operation, e.g. according to Fig. 5, where the number 42 indicates the lower end of the shaft 42 shown in the previous figures, on which are mounted two horizontal stem bodies 48 'corresponding to the rotor bodies 48 but at the outer ends. connected by two oblique whip pieces 49. In this case, the shaft clearance must be large enough to achieve parallel rotation. The rotor bodies are preferably made with more or less sharpened front edges, while the rear edges can be flat or made or provided with vortex-forming bodies, in order to provide an aerodynamic turbulence which increases the fluidizing effect.

The device according to the invention does not necessarily have to be provided with three identical screen surfaces, but by carefully selecting suitable nets or perforated sheets 7 ply 1223 perforated sheets can be formed into a web consisting of e.g. two outer layers of short fibers around the inner layer of long fibers. . using the selected screen types. Experiments have shown that the device can also be used for fibers that are longer than the type of fiber that can normally be processed po. on a device of this type.

Figure 6 shows a modified embodiment in which the rotor bodies are mounted on horizontal shafts. Numbers indicating parts in the previous figures indicate equivalent means in Figure 6. The container 1 is provided with a modified bottom part with a net 15 with a U-shaped cross-section and a flat central part. Parallel to this are two horizontal shafts 5 * each provided with an array of rotor fragments 149 »designed to rotate in the same direction by means of a motor drive 38, 40, the outer circumferential portions of the rotating members 148 running in a region close to the screen base 15 at right angles to the base . As shown by the rounded circumferential portions, the few rotating bodies indicated by the number 50 * are shaped with a small pitch like a propeller to generate a flow of pulp along the curved side portions of the screen base 15 along one side and in the opposite direction along the other side. In this way, the rotating bodies both whip the substance and move it around in the tank.

An important feature of the invention common to both devices of Figures 4 and 6 is that the rotating bodies are designed to rotate in a non-parallel plane with respect to the screen surfaces 15 * 16, with the circumferential portions working very close to the screen surfaces to maintain a zone of efficient fluidization. , which fibers are guided by centrifugal forces towards the screen surfaces 15, 16 substantially in the direction in which the fibers pass immediately through the screen surfaces. Another feature common to both examples is that the disintegrant flows along the inside of the screen surfaces 15, 16 to obtain a uniform outflow of fibers through the screen surfaces 15, 16. The container 1 can be covered with a lid part which is an air permeable substance which allows too much air to flow out if the fibers are fed into the container with a quantity of transport air exceeding the amount of air sucked out through the exhaust fan 26 but keeping the fibers inside the container.

The amount of fibers in the tank is adjusted by the amount of feed relative to the amount of outgrowth so as to maintain a constant profile of fiber flow along the screen surfaces. Surprisingly, however, experiments show that it is possible to attenuate the path of evenly distributed fibers without maintaining said unchanged profile; it is possible to feed the fibers in measured amounts at intervals and to continuously achieve a uniform layer of fiber on the wire until the container is practically empty, which is a great advantage in the device according to the invention.

The whip pieces may have any suitable shape, e.g., wire pieces, and may be designed to rotate in any suitable manner so that their circumferential portions are moved in rapid order toward and away from the screen area cooperating with the whip piece.

The suction area adjusting damper 32 can be divided into parts, as shown by the broken lines in Fig. 3. In this case, the parts can be adjusted separately to adjust the shape of the suction area, and thus if a longitudinal area in which the fibrous layer is thinner or thicker is to be made in the fibrous layer, the parts or part below this area must be adjusted so that the the suction area is increased or decreased. When the machine is used continuously for a long time, fibers or foreign objects can clog parts of the screen surfaces or wire, creating a thinner area along the length of the web. This can be prevented by separately adjustable damper parts and the control can take place by means of automation. It is clear that this method for controlling the thickness of the web formed by suction can be used not only to achieve a uniform cross-section of the fibrous layer but also as a means of adjusting the thickness of the web in general. In addition, these thickness adjusting means can be used for device types other than po. with a type of device, i.e. * in which the constituents forming the substance are placed on the fracturing surface by suction.

It should be noted that the oblique screen surfaces preferably have to form free areas when viewed in the direction of the centrifugal forces provided by the rotor bodies, which helps the fibers to penetrate through the screen surfaces. A minor disadvantage of this is that some of the fibers are directed directly toward the inner surface of the outer wall plate 50 where the fibers accumulate, with the risk of larger fiber piles falling on the newly formed fiber layer on the wire, but this danger can be avoided by flushing air. Another way to avoid this problem could be to replace the wall plate 50 with a horizontal roll, the longitudinal part of the surface of which covers the three-sided space between the screen surfaces 16 and the wire. The fibers deposited on this roll can be continuously removed from the outside, whereby the purge air duct 52 and the closure 56 can be dispensed with.

Claims (17)

A method for spreading loose fibers or particles on a mold surface, preferably for dry making paper, the mold surface consisting of a movable perforated carrier belt (20), the material to be sprayed being fed and the material agitated by means of agitating means (48, 48 ', 49) in an elongate distribution tank; provided with one or more walls (16) through which the fibers can flow and which extend over the carrier strip (20) and in which the material is continuously discharged through the wall part (16) by means of an air flow sucked through the carrier belt and settling on the carrier belt, agitated by means of a velocity component directed outwards to flow through the wall part (16), characterized in that the substance in the container is made to perform a parallel general flow movement along the permeable wall part (16) in the longitudinal direction of the container, and that ai the flow is recirculated in this feed path by means of a return cycle, whereby the excess material is maintained in the recycled material flow relative to the material flowing through the wall part (16). A method according to claim 1, characterized in that the restoration of the material flow is performed in the opposite direction along the corresponding flow-through wall part over the carrier strip, whereby the material flow or a part thereof is subjected to the outward direction. Method according to Claim 1 or 2, characterized in that a new substance is added to the circulating substance flow at one or more points in the flow path. A method according to claim 1, 2 or 3, characterized in that the material flow between the feed and return feed paths is guided by a clearly curved path at the outermost part (62) which removes any lumps from the bypass. A method according to any one of claims 1 to 4, wherein the agitating member is a rotor whip blade (48), the rotor axis of which extends in the longitudinal direction of the container parallel to the permeable wall portion, characterized by causing or maintaining a parallel flow of material over the entire flowing wall portion. (16) by means of whip flaps (5), at least some of which are shaped or arranged to provide a parallel axial fan action along said entire length, wherein a corresponding additional rotor in the axial direction (Figure 6). Method according to one of Claims 1 to 4, characterized in that both a parallel flow of material along the entire length of the flowing wall part (16) and a force acting on the material against this wall part are provided by a plurality of rotors (42, 48) with separate whip vanes. ), which are rotated about parallel axes, each of which is in the normal plane of the wall part (16), this wall part being mounted obliquely with respect to the plane of rotation of the individual rotor blades. A method according to claim 6, characterized in that the material flow return movement along the opposite longitudinal wall part (16) is provided by rotors (42, 48) provided with the same whip blades, so that these are arranged in a median longitudinal plane to affect the flow of matter. An apparatus for carrying out the method according to claim 1, comprising a longitudinal distribution tank (2) arranged above a movable carrier belt (20), which belt is arranged to receive layers of material fibers or particles from a distribution tank provided with a fiber or particle supply port. with means and a longitudinal flow-through outflow wall part (16) for continuously feeding the filled substance of the container (1) and means for agitating and acting out the substance towards the inner side of the outflow wall part (16), means for sucking air below the movable carrier 612 2 3 holes for placing and depositing fibers or particles from the dispensing container on the strip through a carrier belt, characterized in that the dispensing container is further connected to members (4R, 51) or provided with such means for circulating the substance filled in the container in parallel flow along the outflow wall portion (16) in its longitudinal direction over the carrier strip (20) and to the deflection and return members or provided with such means for circulating the flow of air-fluidized material thus obtained. Device according to claim 8, characterized in that the means arranged inside the container for influencing the fluid are arranged in each section of the fluid flow only to act on a part thereof with an outwardly directed force component against the outflow wall part (16). 9 61223 Device according to claim 8, characterized in that the material flow return means consist of a flow-through wall part (16) corresponding to said and arranged in the same plane and parallel therewith and in cooperation with means agitating the return flow and at least locally influencing the flow in the outward wall part (16). ). Apparatus according to claim 8, comprising a rotor with whip vanes rotatably arranged about an axis (5) extending substantially horizontally in the longitudinal direction of the container parallel to the outflow wall (15), characterized in that the whip vanes are at least partially so arranged or formed , that as they rotate cause the substance to move in the axial direction of the rotor in the same direction along the entire outflow wall (16) (Fig. 6). Device according to Claim 8 or 9, characterized in that a row of rotors is arranged outside the outflow wall (16), each axis of rotation (42) being substantially in the normal plane of the outflow wall, each provided with whip vanes (48) whose tip in the respective plane of rotation wipes a small tangential area of the outflow wall (16), which wall 12 612 2 3 is generally oblique to the plane of rotation of the vanes. Device according to claim 10 or 12, characterized in that the flow-through wall (16) for material flow or return flow forms symmetrically opposite wall parts of the container, in which the rotors with whip blades are arranged in the plane of symmetry of the wall part so that the whip-blades (48) rotate act on the substance on both wall parts in the same way as regards agitation and ejection against the respective wall parts (16) and on the transport of the substance in opposite directions along them. Device according to Claim 12 or 13, characterized in that the whip blades of the two adjacent rotors are axially displaced and in that the rotors are arranged in an overlapping distance which is only somewhat greater than the radius of the longest whip blade (48). Device according to claim 12, 13 or 14, wherein the outflow wall part (16) consists of a screen mesh material, characterized in that the lower part of the container is formed by longitudinal mesh walls (16) converging downwards and extending substantially linearly in the longitudinal direction of the container. the side walls (16) at the ends of the container are interconnected by sealing deflection end wall portions (6) which in each plane form a substantially semicircular transition point with the mesh wall (16). Device according to Claim 13, characterized in that cover plates (50) are arranged outside the downwardly converging flow-through wall parts (16) which are inclined to the plane of rotation of the whip blades to form a downwardly directed purge air flow ducts (54, 58). Device according to one of Claims 8 to 16, characterized in that the means for deflecting the flow of material between its path of travel and return consist of relatively strongly bent guide surface parts connected to the outlet opening (62) for heavier particles of the flow of material.