DK149494B - PROCEDURE AND APPARATUS FOR DISTRIBUTING LOOSE FIBERS OR PARTICLES ON A FORMAT SURFACE, PREFERRED TO USE IN WOODEN PAPER PAPER - Google Patents

Description

U9494

The present invention relates to a method for distributing loose fibers or particles on a forming surface / preferably by dry-making paper, and, moreover, of the kind set forth in the preamble of claim 1. A method of this kind is applicable in several known dry forming plants, cf. the specifications of Danish patent application No. 5702/67 and British patent No. 1,375,356.

For producing a fiber layer for practical production of e.g. paper, it is necessary to strive for both a large fiber spreading capacity and a high degree of uniformity of the layer of spread fibers. About the two known methods mentioned, it can be said briefly that they each so well satisfy one of these conditions, but not the other.

British Patent Specification No. 1,376,356 discloses a plant in which the distributor container consists of a recessed cylindrical container with a wrapper of mesh material having a top of a material supply slot extending along the entire length of the cylinder container. Inside the cylinder, axially disposed 20 is a needle rotor whose needle tips flick along the inside of the shroud. The fibrous material is supplied through the said Upper Slit evenly along the entire length of the container, and inside the container, the radial needles of the needle rotor whip the fibrous material around and thereby keep it disintegrated and air-fluidized and partly influence it to gradually exit through the web. occurring centrifugal action on the air and fibers. The outgoing fibers are deposited on the molding belt by means of an air flow which is sucked downwards through the perforated belt, and this air suction also acts directly on the air and the fiber content of the net cylinder, so that the fibers are almost sucked out of it, but with greatly increased capacity. due to the effect of the rotor needles in ejecting the fibers and reorganizing the fibers just inside the inside of the mesh.

149494 2

At this plant, a fiber discharge capacity of practically usable size can probably be obtained, but the plant exhibits the serious disadvantage that it will, for several reasons, tend to form longitudinal strips in the material on the molding strip 5. Thus is. it is a crucial condition that the material supply takes place completely evenly along said supply slit, since an increased supply at one or more local areas will result in a correspondingly increased fiber delivery from the grid cylinder just off this or these areas, ie. in a stripe formation with increased thickness in the deposited product. Such a completely uniform material supply is very difficult to produce, and in addition, there may occur inside the net cylinder fiber clumps which are simply held in rotation by the needle rotor and thus will reduce the amount of fiber that can exit through the sub-regions. of the cylinder where such lumps occur. In this way, strips of reduced thickness will occur in the finished fiber product on the molding.

20 From Danish patent application no. 5702/67 there is known a plant where these problems are overcome, but in turn the distribution capacity is very low. In this system, a distribution vessel is used in the form of a cylindrical vessel with a flat, horizontal net floor located just above the molding belt. In the vessel is arranged a planing stirrer with two rotors with vertical shafts which, by means of lower tubing blades, hold an air fluid filled in the vessel to maintain a "fluid bed" of fibers which can then exit from the bottom through the net bottom for deposition on the molding belt. . The agitator will act to distribute the material in the vessel so that no special requirements are set for any even material supply and any lumps in the material will be passed around the vessel so that they will not be stationary over the same delivery area for the fibers seen in relation to the direction of movement of the molding, i.e. marked 149494 3 strips in the final product will be avoided. On the other hand, one has to do without an active internal projecting effect on the fibers, ie. the delivery capacity of the distributor container will be largely given only by the effect of the air sucked into the molding strip. This suction air can very well extract a considerable flow of fiber blended air through the mesh bottom of the cylindrical vessel, but in order to achieve a practically reasonable delivery capacity for the fibers, it must be ensured that the agitator works sufficiently efficiently to keep the fiber material disintegrated. For this, in practice, a considerable rotational speed of the stirring blades will be required, and at such a high speed the blades will exert such a projection of the material that only areas around the rotor shafts will occur at the net bottom of the tub. The already low fiber delivery capacity will thereby be further reduced by the fact that the suction air will have free access through the relevant fully exposed areas of the net bottom, and further in the circular bottom of the vessel will tend to deposit a thicker layer of fiber along the bottom diameter 20 in the direction of movement of the belt than out at the sides of the bottom surface.

The invention has for its object to provide a method in which the fiber distribution can take place at high capacity and with little risk of streaking in the delivered product on the molding tape.

This is achieved according to the invention in that the method is carried out as defined in the characterizing part of claim 1. It will be seen that the invention is based on a new basic principle in relation to said known methods, namely in connection with an elongated distribution container being provided. to operate at said circulation at an even rather strong flow of material along the container, across the molding, so as to obtain the desired high capacity by actively externally influencing the flow of material, without local sub-areas of the material, including any fiber clumps, remaining permanently in the same dispensing area in the 149494 4 distribution container, and without requiring any special uniformity in the material supply, The supply to the areas / where the discharge of the material takes place can continuously take place with considerable overcapacity because the excess material simply recirculated, and although the flow of material along the outflow wall will thinning like foals Due to said overcapacity, this thinning will not result in any appreciable reduction in material outflow along the outflow wall.

When cf. claim 2 the circulating material stream is utilized for fiber delivery in both the flow and the return flow, a further increased capacity is obtained. It should be noted that a strong flow of material inside the distributor container externally can be revealed by the fact that the outgoing fibers have a certain velocity component in the flow direction, whereby the concentration of the fibers delivered from the container to the molding strip can be increased in the direction of the material flow. Thus, when the distributor container is transverse to the molding strip, the cross-section of the fiber product on the strip may exhibit a correspondingly increasing thickness from one side of the strip to the other, even though the distribution is quite even, ie. without streaking. Such an increasing thickness of the cross-sectional profile of the product will normally be undesirable, but it turns out that just as specified in claim 2, the necessary correction will be obtained towards a completely uniform profile thickness, namely because the said bias in the profile structure will also be present along the return stream, but here with the opposite orientation, whereby the sum of the deposits from the two streams will give the uniform thickness of the fiber layer on the moving molding tape.

Since no uniformity requirements are laid down in the material supply, this can be carried out in a simple manner as set out in claim 3.

149494 5

Already for space reasons, it is advantageous to carry out the redirection between the flow and return flow of the material along distinctly curved paths, and one can hereby cf. Claim 4 provides for the separation of any fibrous clumps 5 by utilizing the rather violent ejection effect which such clumps will undergo upon passing through the heavily curved webs.

When using ejector whip blades in distributor containers, as is known in principle from the aforementioned GB-PS 10 1,376,356, the invention can be cf. Claim 5 utilizes these blades to also effect or support the actual flow of material. A preferred mode of utilization is set forth in claim 6, in which the said method will achieve that the material in the material flow can be held in a well-defined manner against a flat wall part along which the flow takes place, and it is thereby particularly convenient to control The material flow as claimed in claim 7, since a distributor container can be used as a simple vessel whose opposing longitudinal walls constitute the efficient flow-through wall parts which can be made of classification mesh material. The distribution capacity will depend on ia. the speed of the whipping rotors and thus the impact on the material and the height of the vessel walls.

The invention also relates to an apparatus of the kind referred to in the preamble of claim 8 for carrying out the method, which is characterized by what is stated in the characterizing part of the claim. In the claim 9, in any cross-section of the material flow there will be one or more areas in which the flow can flow without any significant outward influence, ie. the flow may be sufficient for it to be material-consuming to all of the outflow areas or the entire outflow area along the retaining wall.

149494 6

However, although the fibers used are very light, they will search downwards, and with purely horizontal action from the whipsaws, the resulting fluidized material flow as a whole will search downwards if caused to flow along a vertical wall in the distributor container.

In the embodiment of claim 15, i.e. by using a V-shaped cross-section of the distributor container, the flow of material in the general or site-wide horizontal expression toward the walls will be affected in an upward direction sufficiently that the flow can proceed substantially in a horizontal direction along the container walls.

According to claim 16, it is achieved that the fibers emerging from the distributor container can be lowered in a well-defined manner against the molding strip no matter how high the container is, and furthermore, the delivery to the molding strip can be effected along a relatively short stretch thereof, regardless of the width of the container. , ie the required suction box below the molding belt need not be very long.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail in connection with the drawing, in which 1 is a side view, partially in section, of a preferred apparatus of the invention; FIG. 2 is a cross-sectional side view of the apparatus; FIG. 3 is a detail of FIG. 1 and 2 from above; FIG. 4 is a perspective view of FIG. 1 partly in section; FIG. 5 is a view of a modified retailer, and FIG. 6 is a perspective view of a modified apparatus according to the invention.

149494 7

FIG. 1 shows an elongated fiber distribution container as a whole denoted by 1 and formed with two semicircular end sections 2, each with an upper half-cylinder portion 4 and a lower cone-stub portion 6 with a semicircular bottom plate 8. The end sections 2 are joined by vertical side plates 10 between the upper cylinder portions 4 and these parts 1-10 are made of non-perforated metal sheet material. Between the side plates 10 and the end portions 6 and 8, a sieve bottom as a whole is indicated by 12 and permeable 10 of fibers and air and with a U-shaped cross section corresponding to the end sections 2, ie. with a flat horizontal bottom screen portion 14 and two outwardly and upwardly sloping screen faces 16.

The container 1 is supported by columns 18 across a fine mesh horizontal carrier in the following 15 referred to as the wire 20, which is guided endlessly around rollers 22 and driven by a drive station not shown in the arrow direction. A suction box 24 with a suction fan 26 is arranged below the screen bottom 12 and the wire 28 and supported by beams 19, 20 connected to the columns 18. The suction box is closed at the bottom and the sides and has an upper opening 28 located close to the wire 20 and sealed against it by means of sealing flanges 30. The suction box is provided in one side with a horizontal slide damper 32 with a curvilinear edge part 34 for checking the suction area as described in further detail below. At one end portion 2 is provided a bracket 36 which supports a motor 38 which, by means of a chain drive 40, pulls four vertical shafts 42 running in bearings 44 mounted on transverse struts 46 which in turn are supported by the upper edges of the side plates 10. The shafts 42 are arranged in series, extending transversely of the wire 20 in the vertical plane of symmetry of the container and each provided with three pairs of diametrically opposed and radially mounted flat, elongated rotor bodies 35 48, the length of which is adapted in such a way that their outer peripheral parts during rotation will pierce regions 149494 8 at a short distance from the inclined screen faces 16, and furthermore, the lower rotor bodies are positioned just above the bottom screen portion 14. The lower rotor bodies are arranged so that they rotate side by side in a a common horizontal plane over the bottom sight portion 14 while the other rotor bodies are set apart and at their length arranged to rotate in areas that partially overlap.

Along the parallel long sides, the container is provided with 10 exterior wall plates 50 which together with the side plates 10 form rinsing air ducts 52 which are closed in the sides of plate pieces 54. Wall plate 50 and plate pieces 54 extend close down over the wire 20 and enclose a substantially triangular space between the inclined screen surfaces 16 15 and the wire 20, which space is protected from the surrounding air with the exception of the upper opening of the rinsing air duct 52. The lower edge of the wall plates 50 is bent and thereby forms an air lock 56 through which the wire can pass with a layer of fibers deposited thereon as described below.

In operation, the shafts 42 are rotated in the same direction, moving the peripheral parts of the rotor bodies at a speed of about 50 m per second. second. This rate is suitable for the treatment of e.g. cellulose fibers, but can be adapted to the desired product and can vary widely.

An air flow is provided through the screen bottom 12, the wire 20, the suction box and out through the suction fan 26. Similarly, air is drawn through the purge air ducts 52. A disintegrated material e.g. cellulose fiber pulp is fed to the container through a fiber spreading inlet 58 approx. up to a level at the level of the upper rotor bodies and agitated vigorously by the fast-rotating bodies 48, which will thereby whip violently through the material. In the unidirectional rotation of the rotor bodies, the fiber material is substantially flung against the opposing sloping screen surfaces 16, whereby the surface profile of the material will extend substantially as indicated by a dotted line a in FIG. 2. The material carried by the sloping screen surfaces 16 is forced by the rotor bodies 48 to move along the respective faces in a relatively slow flow around the container along the sides and ends thereof. The fibers thereby passing the areas coated by the rotor bodies are lively whipped and repositioned, and the fluidized state persists until they reach the next whipping area with said flow. Thus, the inclined screen surfaces 16 and the outer edge portions of the bottom screen portion 12 are continuously coated by an efficient fluidized flow of fibers, which can thus be immediately sucked through the screen floor 12. After passing these screen surfaces, the fibers will follow the suction air and deposit on the wire 20 which separates. the fibers from the air and in this way form a web of loose fiber material which is carried with the wire through the lock 56 for fixation or other desired purposes.

Some of the fibers will include due to static electricity, the inside wall of the outer wall 50.54 is deposited, but this is counteracted by the purge air flow down the inside of these walls, the flow having been oriented in the duct 52. By sucking air in this way the wire is obtained. furthermore, an increased effect of the tendency for possibly thinner areas on the wire to be filled due to their less suction resistance, whereby floating fibers are attracted at a concentration higher than otherwise found across the wire to form the desired even distribution of the fibers. this. In this way, if fibers are sprinkled in increased amount from the sieve portions adjacent to the areas which are coated a short distance by the peripheral portions of the rotor bodies, the resulting uneven distribution of the fibers will be counteracted. It should be noted that the longest path to fi ber passage from the screen surfaces to the wire is from the upper screen surface portions, ie. in the areas near the highest rotational velocity of the peripheral portions of the rotor alloys, which in turn means the most active areas for fiber scattering.

5 The flow of material inside the container is reversed at each end section 2 and thrown around and up along the semi-conical sides 6 towards the region of the cylindrical end portions 4, from which the material is again directed by means of a baffle plate 60 towards the longitudinal side portions and the bottom etc. During the reversal of the stream, any heavy particles, fiber clumps or other unwanted bodies may concentrate in the region above the cone portion at the periphery where they can be removed. For this purpose, a tangential outlet tube 62 is provided, the opening towards the container 15 being a slot partially closed by means of a neatly mounted damper plate 64 for adjusting the height of the slot to control the outlet quantity of e.g. foreign objects. The outlet tube 62 can be connected to the container by means of recycling in a known manner.

The rotor bodies 48 can take many forms to perform their whipping function, e.g. as shown in FIG. 5, where 42 indicates the lower end of shaft 42 shown in the previous figures, on which shaft is mounted two horizontal arm bodies 48 'corresponding to rotor bodies 48, 25 and connected at the outer ends by two inclined whip bodies 49. Preferably, the rotor bodies should are performed with more or less sharpened leading edges, while the trailing edges may be flat or even shaped or provided with vertebral bodies to produce an aerodynamic turbulence to enhance the fluidized action.

The apparatus according to the invention need not necessarily be provided with three identical sieve surfaces, since by careful selection of suitable mesh or perforated U9494 11, a web of loose fibers consisting of e.g. two outer layers of short fibers around an inner layer of long fibers, the different types of fibers being sorted by means of the selected screening types concerned.

5 Tests have shown that the apparatus is applicable even to fibers longer than the length of the type of fiber which can normally be treated in apparatus of the type in question.

FIG. 6 shows a modified embodiment in which the rotor bodies are mounted on horizontal shafts 5. The numbers indicating parts in the previous figures indicate equivalent means in fig. 6. The container 1 is provided with a modified bottom part with a mesh 15, the cross-section of which is U-shaped with a flat center part. Parallel to this, two horizontal shafts 5 are each provided with a set of rotor bodies 148 arranged for rotation in the same direction by means of motor 38.40, the outer peripheral portions of the rotary bodies 148 covering a region near the sight base 15 at a right angle. on this. As indicated by rounded peripheral portions, some of the rotary bodies, denoted 50, are formed with a slight increase as a propeller to form a stream of longitudinal fiber mass along the curved side portions of the screen base 15 in one direction along one side and in the opposite direction. along the other side. In this way, the rotary bodies serve the combined purpose of whipping the material and moving it around the container.

An important feature of the invention, common to both apparatus shown in Figures 4 and 6, is that the rotary bodies are arranged to rotate in a non-parallel plane with the screen faces 15,16 with the peripheral parts working close to the screen faces to maintain a zone of effectively fluidized fibers which are directed by centrifugal forces to the screen surfaces 15, 16 mainly in the direction in which the fibers will immediately pass the screen surfaces. Another feature common to the two examples is the flow of the disintegrated material along the inside of the screen surfaces 15, 16 for the sake of a uniform flow of fibers through the screen surfaces 15, 16. Container 1 can be covered with a cover section of an air-permeable material that permits excess air outflow if the fibers are supplied to the container by means of a transport air quantity exceeding the amount of air sucked out 10 via the suction fan 26 but holding the fibers inside the container.

The amount of fiber in the container is controlled by the amount of feed relative to the output amount in order to maintain a constant profile of the fiber flow 15 along the sieve surfaces. However, experiments show surprisingly that it is possible to produce a web of evenly distributed fibers without maintaining said constant profile; it is even possible to feed the fibers in metered amounts at intervals and still achieve an even 20 layer of fiber on the wire until the container is virtually empty, which is a great advantage of the apparatus according to the invention.

The whip bodies may be of any suitable design, e.g. formed by wire bodies, and they may be arranged for rotation in any suitable manner so that their peripheral parts are moved in rapid succession toward and away from the sieve area cooperating with whip bodies.

The suction damper 32 for controlling the suction area can be divided into sections as indicated by dashed lines 30 in FIG. 3. The sections can then be individually adjusted to adjust the shape of the suction area and in this way control any. variations in the thickness of the fiber layer across the wire, ie. if the fiber layer is to be provided with a longitudinal zone where the fiber layer is thicker or thinner,

'"IN

The section or sections below the zone must be adjusted in such a way as to increase or decrease the respective suction area. In continuous operation for an extended period, parts of the screen surfaces or wire may be clogged by fibers or foreign bodies, whereby a thinner zone will appear longitudinally of the web. This can be counteracted by the individually adjustable damper sections and can be controlled by automatic control. It will be appreciated that this method of controlling the thickness of a web material formed by suction is not only useful for correcting the uniformity of the cross-section of the fiber layer, but can also be used advantageously as a guide for the thickness of the web material in general. In addition, these thickness control means can be used in connection with other types of plant than the present one, ie. wherein the sub-constituents of a material are deposited on a forming surface by suction.

It should be noted that the inclined screen faces 20 must preferably be formed with free luminous areas in the direction of the centrifugal forces caused by the rotor bodies in order to assist in the penetration of the fibers by the screen faces. A minor disadvantage of this would be that some fibers were directed directly to the inner surface of the outer wall plate 50, where they would accumulate thereon at the risk of falling of larger fiber accumulations on the newly formed fiber layer on the wire, but this risk is mitigated. by means of the rinsing air flow through the duct 52. Another way of preventing this problem could be to replace the wall plate 50 with a horizontal roller which, with a longitudinal part of its surface, covers the triangular space between the screen surfaces 16 and the wire. . Fibers deposited on such a roll can be removed continuously from the outside and the purge air duct 52 35 and the lock 56 can then be avoided.

Claims (15)

149494 PME8TKRAV: A method, preferably by drying paper, and distributing loose fibers or particles on a molding surface of a moving, perforated carrier (20), whereby the material to be distributed is indigenous and by means of material agitating. means (48, 48 ', 49) are kept air-fluidized in a distributor container formed with one or more flowable walls or wall portions (16) extending over the carrier (20) and the material by means of a carrier (10). (20) suctioned air flow is continuously discharged through the flow-through wall portions (16) and deposited on the carrier (20), characterized by the use of material agitating means (48, 49, 51, 148) thus arranged and positioned. in the distributor container, and wherein the flowable wall portion (s) (16) is shaped and disposed so that said means (48,49,51,148) affect the material for movement with a velocity component which is directed outwardly toward the genes. flowable wall portions (16), and for still new supply 20 of the material to the material agitating means (48,49,51, 148), the material is affected to effect a circulating flow movement in a web by feeding along the flowable wall portions (16). generally parallel to the plane of the carrier (20). Method according to claim 1, characterized in that the return of the material flow is carried out in the opposite direction of the feed and that both the feed and the return over the support belt extend along flowable wall parts. Process according to claim 1 or 2, characterized in that new material is fed to the circulating material stream at one or more localities along the flow path. 149436 Method according to claim 1,2 or 3, characterized in that the flow of material between its feed path and return path is controlled along a pronounced curved path, from which 5 any lumps in the passing material are removed. Method according to any one of claims 1-4, wherein whip blades (148) are rotated in planes perpendicular to the flow-through wall (15) shaped as a sub-cylinder, characterized in that one acts or supports the unidirectional flow of material. along the entire length of one side of the flow-through wall (15) by means of some (51) of the whip wings (5) formed or arranged to produce a unidirectional axial blower function along the entire length of said 15 side, using a return of the flow of material along the other side of the flowing wall (15) is used, further, similar whip blades which are rotated to move the flow of material in the opposite axial direction (Fig. 6). Method according to any one of claims 1-4, characterized in that both the unidirectional flow of material along the entire length of the flow-through wall portions (16) in one side of the distributor container and the outward force effect of the material by means of a plurality of longitudinal directionally spaced vane rotor blades (42, 48) rotating about parallel axes each located in a normal plane to the wall portions (16), these being oblique to the rotation plane of the individual rotor blades. Method according to claim 6, characterized in that the movement of the material flow along mutually opposed longitudinal flow-through portions (16) is effected by the same whip-wing rotors (42, 48), which are arranged upright in the median plane of the distributor container for influencing the material flow at the opposing longitudinal walls with mutually opposite directions of movement along them. Apparatus for carrying out the method according to claims 1, 5 comprising an elongate material distribution container (2) disposed over a moving carrier (20) for receiving a layer of material fibers or particles from the distribution container, which * has a fiber opening or fiber supply opening. particulate material and longitudinal, flowable walls or wall parts (15, 16) for successive delivery of material filled into the container (1) and means for actuating the material and influencing it towards the inside of the flowing walls or wall parts (15,16), wherein means for sucking air through the perforated carrier are provided below the moving carrier to reduce and deposit the fibers or particles emitted from the distribution container, characterized in that the distribution container further is connected or provided with means (48,51,148) for effecting the material filled in the container to move generally proceed in a continuous flow along the flow-through wall portions (15, 16) in their longitudinal direction across the carrier (20), and with redirection and return means for recirculating the flow of air-fluidized material thus provided. Apparatus according to claim 8, characterized in that the means (48,41,148) arranged inside the container for influencing the flowing material are arranged to affect in only a cross-section of the material flow only a sub-region thereof with one against the flowable wall parts. (15.16) outward force component. Apparatus according to claim 8, characterized in that the container has permeable wall portions (15, 16) on both sides. U9496 Apparatus according to claim 8, comprising one or more whip-wing rotors disposed rotating about an axis (5) extending substantially longitudinally of the container parallel to the partially cylindrical shaped flow-through portions (15) thereof, characterized by the whip blades are designed for at least a part (51) to induce said flow movement of the material. (Fig. 6). Apparatus according to claim 8 or 9, characterized in that a series of whip rotors with parallel rotary axes (42) are arranged, each located substantially in a normal plane to the flow-through wall parts (16) and each formed with whip wings ( 48) whose tips in the respective rotational planes cover a small tangential region of the flow-through wall portions (16) which are generally inclined to the rotational plane of the blades. Apparatus according to claims 10 and 12, characterized in that the flow-through wall parts (16) are symmetrically opposed and that the whip rotors (48) are arranged in the plane of symmetry of the opposing walls so that during their rotation they affect the material at the opposing walls. or wall parts in the same way agitation and ejection against the respective walls (16) and transport of the material in the respective opposite directions along these. Apparatus according to claim 12 or 13, characterized in that the whip blades (48) are arranged in an overlapping manner on two neighboring rotors at a distance which is only slightly larger than the radius of the longest whip blades (48). Apparatus according to claim 12, 13 or 14, wherein the flowable wall or walls or parts are constituted by classification mesh material, characterized in that the lower part of the container is provided with longitudinal mesh side walls (16) that converge downwards and in any level has a generally rectilinear course in the longitudinal direction of the container, which sidewalls (16) at the container ends are interconnected with tight guide end wall parts (6) which