EP0119124B1 - Fibre distribution in a fleece - Google Patents

Fibre distribution in a fleece Download PDF

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Publication number
EP0119124B1
EP0119124B1 EP84400358A EP84400358A EP0119124B1 EP 0119124 B1 EP0119124 B1 EP 0119124B1 EP 84400358 A EP84400358 A EP 84400358A EP 84400358 A EP84400358 A EP 84400358A EP 0119124 B1 EP0119124 B1 EP 0119124B1
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EP
European Patent Office
Prior art keywords
fibres
conveyor
fibers
felt
jets
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84400358A
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German (de)
French (fr)
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EP0119124A1 (en
Inventor
Francis Mosnier
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Saint Gobain Isover SA France
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Saint Gobain Isover SA France
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Publication of EP0119124A1 publication Critical patent/EP0119124A1/en
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    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/732—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by fluid current, e.g. air-lay
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/724—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged forming webs during fibre formation, e.g. flash-spinning
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4209—Inorganic fibres
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4209—Inorganic fibres
    • D04H1/4218—Glass fibres
    • D04H1/4226—Glass fibres characterised by the apparatus for manufacturing the glass fleece
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/736—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged characterised by the apparatus for arranging fibres
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H17/00—Felting apparatus

Definitions

  • the invention relates to techniques for forming fiber felts in which the fibers are produced by centrifugation. More particularly, the invention relates to those of these techniques in which the fibers are produced by directing the stretchable material from the outside to the periphery of one or more centrifugation wheels and are entrained by a gas current along the peripheral wall of the centrifuge wheel (s).
  • the mode of reception of the fibers in order to form felts in the context of these techniques includes a certain number of very specific provisions for this type of drawing.
  • the wheels are usually arranged so that their axis of rotation is horizontal or close to this position.
  • the gas streams which participate in the formation of the fibers by entraining them, but also by exerting a drawing action near the centrifuge wheels, are usually generated parallel to the axis of rotation. It is also preferable to ensure that the fibers, whatever the area of the wheel where they originate, undergo a uniform treatment. For this, the gas stream must run along the wall of the wheel at a short distance and being approximately parallel to the peripheral wall. The gas streams under these conditions are, at least originally, close to the horizontal.
  • centrifugation techniques even in their most efficient modes of implementation, such as those described in the aforementioned patent application, do not make it possible to completely avoid the projection of fiberized products immediately below the fiberizing device or slightly in front of it on the path followed by the gas stream carrying the fibers.
  • the reception of the fibers in order to form the felt is therefore advantageously located at a certain distance from the centrifuge device. In this way a dynamic sorting takes place which automatically leads to the elimination of the coarsest infibrated particles.
  • a pit is usually arranged under the centrifuge to receive the infibers, while the reception, constituted by a perforated conveyor, is placed at a distance which depends on the characteristics of the gas flow carrying the fibers.
  • the fibers carried by the gas streams are directed to an elongated receiving chamber in the general direction of these streams. In this chamber, the gas streams are gradually slowed down. This avoids an excessively brutal impact of the fibers with the conveyor which closes the reception chamber at its base.
  • the slowing down of the gas streams carrying the fibers is due to the entrainment of a mass of surrounding air, a mass which increases as the gaseous current "meter" progresses.
  • the conveyor extends in a direction which corresponds roughly to that followed by the gas stream.
  • the quantity of fibers necessary can thus be from 15 to 20% , more important when the distribution is not satisfactory.
  • the mechanical properties of the products are also very significantly influenced by the homogeneity of the distribution of the fibers.
  • the distribution of the fibers on the felt prepared in the traditional way is not satisfactory.
  • the invention proposes to improve this distribution.
  • the use of these additional jets is characterized in that the jets are emitted in the immediate vicinity of the origin of the current carrying the fibers so that their modification is as effective as possible.
  • the emission of additional jets is located in the receiving chamber at a distance from the conveyor.
  • the fiber drawing technique and the type of installation in which the invention is implemented are of another nature, as we have indicated above, according to the invention then, the additional gaseous jets have no not intended to spread the gas stream carrying the fibers or to vary its direction periodically, finally, still according to the invention, the emission of the additional jets is located near the conveyor and not at the origin of the gas stream in the reception room.
  • jets emitted can be very energetic, in other words they can be emitted under high pressure, but it has been found experimentally that jets at low pressure also make it possible to obtain very satisfactory results and at lower cost.
  • the modification of the trajectory of the gaseous current carrying fibers, in these techniques, requires a relatively high energy expenditure which is not the case of the invention.
  • the emission of the additional jets takes place along the side walls bordering the conveyor, in other words substantially in the direction of propagation of the current carrying the fibers.
  • the jets are directed towards the stream transverse to its trajectory, perpendicularly if not at a pronounced angle with this trajectory.
  • the angle of the additional jets with the direction of the gas streams carrying the fibers, or that with the side walls of the receiving chamber, which is equivalent is too large l
  • the effect of these jets on the distribution decreases and can even cancel out.
  • the angle of the jets with the walls is advantageously less than 20 °.
  • the energy communicated to the additional jets is relatively low. We have seen that the pressure from the jet to the orifice does not need to be high.
  • the volume of gas required is also relatively small compared to the mass of gas carrying the fibers which is sucked under the conveyor. This quantity of blown gas is adjusted according to the intensity of the effect to be obtained. In a simplified manner, it can be considered, within certain limits, that the effect is all the more marked the greater the quantity blown.
  • the emission conditions are such that the gas jets have a speed of the order of that of the gas streams, at the same level, or substantially greater.
  • the additional jets are emitted along the gas stream. They do not need to cover the entire height of the side walls. Their location at the mean level of the gas flow carrying the fibers is sufficient.
  • these additional jets can advantageously be slightly offset towards the conveyor. The blowing should not however be carried out along the conveyor which could lead to completely sweeping the fibers which are deposited. Preferably a minimum distance of 0.3 m is left between the conveyor and the point of emission closest to the conveyor.
  • the part of the installation shown in FIG. 1 essentially comprises the device for forming the fibers and the receiving chamber in which the felt is formed.
  • the fiber-forming device consists of a set of three wheels 1, 2, 3 rotating in opposite directions to each other, and rings 4, 5 generating a gas stream at the periphery of the fiberizing wheels.
  • the material is supplied from an oven or a crucible 6.
  • the material flows through a chute 7 onto the first wheel 1 called the distribution wheel because its main role is to accelerate the material and that few fibers detach from it.
  • the material accelerated in contact with the wheel 1 is sprayed onto the wheel 2. Part of the material adheres to this wheel then, under the effect of centrifugation, is sprayed in the form of fine filaments. The other part of the material is returned to the wheel 3 where it adheres and forms filaments in the same way as for the wheel 2.
  • the filaments which detach from the wheels are entrained (and drawn when they are in suitable conditions) by a gas stream blown from the blowing rings 4 and 5 which surround the wheels from which the fibers detach.
  • an additional crown can surround, at least partially, the wheel 1 when the latter is also able to produce fibers.
  • the device shown is typical of an installation for the formation of mineral fibers, in particular for materials whose melting temperature is particularly high: rock basalt, foundry slag, etc ... Similar installations including centrifugal devices with one, two or four wheels are also commonly used for this kind of production.
  • Means are normally arranged in the vicinity of the wheels, or on the wheels themselves, for spraying a composition of a binder on the fibers entrained by the gas stream. These means are not shown.
  • a hopper 8 which collects the infibrated particles projected directly from the centrifuge device, where those which, because they are too dense, "sediment before reaching the receiving conveyor 9.
  • the horizontal distance separating the fiber-forming device from the conveyor 9 is of the order of 2 to 3 m, which allows a relatively large elimination of fiber particles or insufficiently fiber particles.
  • the receiving chamber in which the fibers and the gas streams carrying them circulate is practically closed.
  • the only openings allowing the introduction of a significant quantity of outside air are located behind the centrifuge and at the level of the hopper 8. These openings and the induced air which they allow to enter facilitate the good development of the flow gas in the reception room.
  • This receiving chamber is closed at its base by the conveyor 9 and laterally, along the conveyor, by walls 10 and 11.
  • the walls 10 and 11 are advantageously movable in rotation and move in the same direction as the conveyor 9.
  • the chamber is also closed at its upper part which is not shown in Figure 1, for reasons of clarity.
  • Suction boxes 12 and 13 are arranged under the conveyor 9 over the entire length. These boxes which are kept in depression with respect to the receiving chamber evacuate the gases carrying the fibers, after these have been retained on the conveyor.
  • Figure 2 roughly shows the path followed by the gases and fibers.
  • the movement of the gas streams flowing in the receiving chamber is controlled by the drawing gases emitted along the centrifuge wheels. It is controlled by the suction maintained under the receiving conveyor. Added to these effects are those which result from the induction of ambient air.
  • the amount of gas passing through the conveyor 9 is much greater than that emitted by the blowing rings 4 and 5.
  • the gas sucked into the boxes 12 and 13 enters the receiving chamber through openings made to allow entry "induced" air.
  • the openings in question are located mainly at the level of the hopper 8 and on the wall of the chamber on which the fiberizing device is located.
  • the arrows I represent the main lines of the induced air flow.
  • the circulation of the air induced in the hopper 8 is done against the current of the particles projected from the centrifuge wheels. This movement makes it possible to complete the sorting effect sought to separate the fibers from the infibrated particles.
  • the fibers move in the reception chamber in a direction close to the horizontal. This direction bends towards the receiving conveyor under the effect of suction. They are gradually deposited on the conveyor 9 to form the felt 14, the thickness of which increases until it leaves the chamber.
  • the circulation of gases in the chamber is very turbulent, so it is not possible to represent a precise trajectory but only the overall movement.
  • the distribution of the fibers that is obtained in the absence of implementation of the invention is of the type shown in Figure 3. Two defects are usually observed, a hollow in the middle of the felt, or what is equivalent an excess of fibers on the edges, and an imbalance on one side compared to the other.
  • FIG 5 shows on a larger scale a part of Figure 1 on which is shown an embodiment of the invention. According to this mode, blowing nozzles 18 conduct air under pressure to blowing nozzles 19 arranged at the limit between the partitions 16 and 11.
  • a minimum space is always provided at this location so as not to hinder the movement of the partition 11. This spacing is sufficient to pass the nozzles, the end of which, constituting the emitter orifice 20, is flattened to form flat jets.
  • the sealing flap as in Figure 1 is not shown.
  • the figure shows only one side of the device. It goes without saying that similar nozzles are also arranged to blow at the limit between the walls 15 and 10.
  • the axis of the blowing nozzles is substantially parallel to the movable wall 11 so that the emitted jets run along this wall.
  • FIG. 5 five separate nozzles conduct the additional gas at different levels along the wall 11.
  • Other arrangements can be used without modifying the overall operation. It is possible in particular to blow from a single orifice, preferably sufficiently elongated, to distribute the blown gas over a certain height. This is the case for the device represented in FIG. 6.
  • the gas supplied by the nozzle 21 is emitted by the single nozzle 22.
  • the blowing is carried out slightly below the average path of the fibers determined at their origin by the position of the centrifugation wheels, and at a certain distance from the conveyor 9.
  • the vertical position of the blowers can vary within certain limits. Tests make it possible to determine in each case the best position, that is to say the one which makes it possible to obtain the greatest modification for an additional jet whose other characteristics are kept constant.
  • Figure 7 shows the position of the nozzles and the direction of the jets emitted.
  • the nozzles are placed along the walls 15 and 16 and at the end thereof slightly forward with respect to the rotating walls, the end of the nozzle practically at the level where the wall becomes planar. In this position, the jets enter the reception chamber immediately after their emission, which gives them maximum efficiency.
  • the nozzles can also extend further inside the receiving chamber. This does not appear to provide further improvements. In fact, the nozzle which must support itself does not penetrate very far into the chamber. Furthermore, if the nozzle were to advance further, it would constitute a particular point along the wall, on which the fibers could come to hang which is not desirable.
  • Tests were carried out with very variable pressures from 0.1 to 4 bars. The most suitable pressure for each case depends on the blowing nozzles. Indeed, the results, as we will see in the following, depend on the mass of gas blown and therefore when the nozzles offer small orifices it is necessary to use a higher pressure.
  • test results according to the invention for improving the transverse distribution of fibers forming a felt are carried out in an installation of the type presented in FIG. 1.
  • the additional blowers used include a single blowing nozzle on each side of the installation. These nozzles similar to that presented in FIG. 6 have an orifice extended over 500 mm for a width of 25 mm.
  • blowers are powered by a low pressure fan. They are regulated independently of each other by two separate valves.
  • the distribution of the fibers is measured by means of an X-ray probe. This probe is mobile and moves transversely to the conveyor. It operates on the felt leaving the reception room.
  • the analysis of fiber density measurements by absorption of X-rays is made by distinguishing three zones on the felt: a central zone and two lateral zones. These three zones are the same width.
  • the distribution is represented by two values, a "trough rate y which expresses the distribution imbalance between the center and the edges of the felt, and a" slope rate showing the imbalance between the two edges.
  • the hollow ratio is determined according to the formula: and the slope rate:
  • FIG. 8 schematically shows, according to the values of the trough and slope rates, the general shape of the distribution of the fibers transversely to the conveyor. In practice, it is of course necessary to combine a form representing the trough rate and that corresponding to the slope rate.
  • a product is prepared at the rate of 6 tonnes per hour.
  • the felt formed has a mass per unit surface area of 5.5 kg / m 2 .
  • the binder rate is 6.6% of the mass of the felt,
  • the average quantity of gas sucked under the conveyor is around 175,000 Nm 3 / h.
  • the quantities of gas blown along the walls are modified and the trend in slope and trough rates is monitored.
  • the initial distribution is poor, as can be seen in example 1.
  • the trough and slope rates are both relatively high, while for an ideal distribution they must tend to cancel each other out.
  • Examples 2 to 6 are carried out by blowing the nozzles according to the invention at different pressures.
  • Examples 2, 3, 4 and 5 show the progressiveness of the effects obtained by increasing the pressure simultaneously on the two nozzles.
  • the trough and slope rates are significantly reduced.
  • the trough rate even becomes negative.
  • Example 6 (which does not correspond to a satisfactory distribution), is carried out to show the influence of the use of two different pressures. It is noted that the difference in the blowing makes it possible to modify the slope rate profoundly. Means are therefore available through this means for varying the dip rate and the slope rate in a partially independent manner.
  • blowing devices according to the invention can be implemented automatically.
  • the regulation is done in this case continuously from the measurements coming from the X-ray absorption probe.
  • the measured values are processed by means of a computer to arrive, for example, at the expressions of dip rate and slope .
  • An algorithm stored in memory elaborates from these results a response which corresponds to a modification of the flows blown by the nozzles according to the invention by means of the valves arranged on the nozzles.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Nonwoven Fabrics (AREA)
  • Artificial Filaments (AREA)
  • Preliminary Treatment Of Fibers (AREA)
  • Inorganic Fibers (AREA)
  • Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
  • Nuclear Medicine (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)
  • Treatment Of Fiber Materials (AREA)
  • Glass Compositions (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Multicomponent Fibers (AREA)
  • Crushing And Pulverization Processes (AREA)
  • Television Systems (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Cigarettes, Filters, And Manufacturing Of Filters (AREA)
  • Infusion, Injection, And Reservoir Apparatuses (AREA)
  • Materials For Medical Uses (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
  • Polarising Elements (AREA)

Abstract

1. A method of forming a felt of fibres in which the fibres are formed from a material which is in the drawable state, this material being carried over the peripheral surface of one or more wheels to which a rotary movement is imparted and from which the fibres become detached and are thrown into a gaseous current which is directed transversely of the direction in which the fibres are thrown and along the peripheral wall of the wheel or wheels, the fibres thus formed, entrained by the gaseous current, being carried into a receiving chamber in which the base is constituted by a perforated conveyor, the gaseous current carrying the fibres crossing the conveyor, the fibres becoming deposited on the conveyor in order to form the felt, the method being characterized in that one or a plurality of additional gas jets are created on either side of the gaseous current carrying the fibres substantially in the same direction as that of the current, these additional jets being emitted along lateral walls bordering the perforated conveyor.

Description

L'invention est relative aux techniques de formation de feutres de fibres dans lesquelles les fibres sont produites par centrifugation. Plus particulièrement l'invention se rapporte à celles de ces techniques dans lesquelles les fibres sont produites en dirigeant la matière étirable de l'extérieur à la périphérie d'une ou plusieurs roues de centrifugation et sont entraînées par un courant gazeux longeant la paroi périphérique de la (ou des) roue(s) de centrifugation.The invention relates to techniques for forming fiber felts in which the fibers are produced by centrifugation. More particularly, the invention relates to those of these techniques in which the fibers are produced by directing the stretchable material from the outside to the periphery of one or more centrifugation wheels and are entrained by a gas current along the peripheral wall of the centrifuge wheel (s).

La formation de fibres par ces techniques, et notamment de fibres de matériaux verriers, est bien connue. On peut se reporter pour le détail des conditions de mise en oeuvre en particulier à la demande de brevet publiée FR-A-2 500 492 de la Demanderesse.The formation of fibers by these techniques, and in particular fibers of glass materials, is well known. Reference may be made for the details of the conditions of implementation in particular to the published patent application FR-A-2,500,492 of the Applicant.

Le mode de réception des fibres en vue de former des feutres dans le cadre de ces techniques comporte un certain nombre de dispositions très spécifiques à ce type d'étirage.The mode of reception of the fibers in order to form felts in the context of these techniques includes a certain number of very specific provisions for this type of drawing.

En premier lieu, il est important de souligner que les roues sont ordinairement disposées de telle sorte que leur axe de rotation est horizontal ou proche de cette position. Les courants gazeux qui participent à la formation des fibres en les entraînant, mais aussi en exerçant une action d'étirage à proximité des roues de centrifugation, sont habituellement engendrés parallèlement à l'axe de rotation. Il est aussi préférable de faire en sorte que les fibres, quelle que soit la zone de la roue où elles prennent naissance, subissent un traitement homogène. Pour cela, le courant gazeux doit longer la paroi de la roue à faible distance et en étant approximativement parallèle à la paroi périphérique. Les courants gazeux dans ces conditions sont, au moins à l'origine, voisins de l'horizontale.Firstly, it is important to emphasize that the wheels are usually arranged so that their axis of rotation is horizontal or close to this position. The gas streams which participate in the formation of the fibers by entraining them, but also by exerting a drawing action near the centrifuge wheels, are usually generated parallel to the axis of rotation. It is also preferable to ensure that the fibers, whatever the area of the wheel where they originate, undergo a uniform treatment. For this, the gas stream must run along the wall of the wheel at a short distance and being approximately parallel to the peripheral wall. The gas streams under these conditions are, at least originally, close to the horizontal.

Ces techniques de centrifugation, même dans leurs modes de mise en oeuvre les plus performants, tels que ceux décrits dans la demande de brevet précitée, ne permettent pas d'éviter complètement la projection de produits infibrés immédiatement à l'aplomb du dispositif de fibrage ou légèrement en avant de celui-ci sur le trajet suivi par le courant gazeux portant les fibres. La réception des fibres en vue de former le feutre est donc avantageusement située à une certaine distance du dispositif de centrifugation. De cette façon il s'opère un tri dynamique qui aboutit automatiquement à l'élimination des particules infibrées les plus grossières.These centrifugation techniques, even in their most efficient modes of implementation, such as those described in the aforementioned patent application, do not make it possible to completely avoid the projection of fiberized products immediately below the fiberizing device or slightly in front of it on the path followed by the gas stream carrying the fibers. The reception of the fibers in order to form the felt is therefore advantageously located at a certain distance from the centrifuge device. In this way a dynamic sorting takes place which automatically leads to the elimination of the coarsest infibrated particles.

En pratique une fosse est habituellement ménagée sous le centrifugeur pour recevoir les infibrés, tandis que la réception, constituée par un convoyeur perforé, est placée à une distance qui dépend des caractéristiques du flux gazeux portant les fibres.In practice, a pit is usually arranged under the centrifuge to receive the infibers, while the reception, constituted by a perforated conveyor, is placed at a distance which depends on the characteristics of the gas flow carrying the fibers.

Les fibres portées par les courants gazeux sont dirigées vers une chambre de réception allongée suivant la direction générale de ces courants. Dans cette chambre, les courants gazeux sont ralentis progressivement. Ceci permet d'éviter un impact trop brutal des fibres avec le convoyeur qui clôt la chambre de réception à sa base.The fibers carried by the gas streams are directed to an elongated receiving chamber in the general direction of these streams. In this chamber, the gas streams are gradually slowed down. This avoids an excessively brutal impact of the fibers with the conveyor which closes the reception chamber at its base.

Le ralentissement des courants gazeux portant les fibres est dû à l'entraînement d'une masse d'air environnant, masse qui s'accroît au fur et à mesure de la progression du courant gazeux « mαteur •.The slowing down of the gas streams carrying the fibers is due to the entrainment of a mass of surrounding air, a mass which increases as the gaseous current "meter" progresses.

Etant donnée la longueur de la chambre de réception et donc la longueur du trajet des gaz, une certaine sédimentation des fibres s'opère sur ce trajet. Aussi le convoyeur s'étend suivant une direction qui correspond à peu près à celle suivie par le courant gazeux.Given the length of the receiving chamber and therefore the length of the gas path, a certain sedimentation of the fibers takes place on this path. Also the conveyor extends in a direction which corresponds roughly to that followed by the gas stream.

Sous le convoyeur une atmosphère en dépression est maintenue. Sous l'effet de cette dépression les gaz portant les fibres sont aspirés à travers le convoyeur déposant au passage les fibres qu'ils portent. Cette aspiration contribue à infléchir la trajectoire des fibres et des gaz vers le convoyeur.Under the conveyor a vacuum atmosphere is maintained. Under the effect of this depression the gases carrying the fibers are sucked through the conveyor depositing in passing the fibers which they carry. This suction contributes to bending the path of the fibers and gases towards the conveyor.

On comprend que la circulation des gaz et des fibres dans les installations de ce type est soumise à de multiples influences et que la répartition homogène des fibres sur le convoyeur soit délicate à assurer. En plus du flux gazeux participant à l'étirage, il faut tenir compte de l'influence des courants induits qui modifient la répartition des fibres. Il faut tenir compte aussi des courants préférentiels que peut engendrer l'aspiration à travers le convoyeur. Il faut enfin encore tenir compte de la géométrie de la chambre qui peut être la cause de modifications importantes dans la circulation de ces courants.It is understood that the circulation of gases and fibers in installations of this type is subject to multiple influences and that the homogeneous distribution of the fibers on the conveyor is difficult to ensure. In addition to the gas flow involved in drawing, account must be taken of the influence of the induced currents which modify the distribution of the fibers. It is also necessary to take into account the preferential currents that can be generated by the suction through the conveyor. Finally, it is also necessary to take into account the geometry of the chamber which can be the cause of significant modifications in the circulation of these currents.

Si dans les publications antérieures relatives à ces techniques, on s'est efforcé par divers moyens, y compris en modifiant les caractéristiques des gaz moteurs ou celles des gaz induits, d'améliorer les phénomènes aboutissant à la formation des fibres, il ne semble pas que les questions concernant la distribution des fibres dans le feutre aient fait l'objet d'études approfondies. Cette question est pourtant d'une grande importance étant donné que la qualité du produit préparé est directement liée à l'homogénéité de cette distribution. Un produit homogène peut ainsi être beaucoup moins épais et donc nécessiter moins de matière, moins de transport, etc... qu'un produit présentant les mêmes propriétés isolantes mais de mauvaise homogénéité. Pour obtenir en tout point du feutre une masse par unité de surface au moins égale à une valeur que l'on s'impose compte tenu de la qualité du produit final recherché, globalement la quantité de fibres nécessaires peut ainsi être de 15 à 20 %, plus importante lorsque la répartition n'est pas satisfaisante.If in previous publications relating to these techniques, efforts have been made by various means, including by modifying the characteristics of the driving gases or those of the induced gases, to improve the phenomena leading to the formation of fibers, it does not seem that the questions concerning the distribution of the fibers in the felt have been the subject of in-depth studies. This question is however of great importance since the quality of the product prepared is directly linked to the homogeneity of this distribution. A homogeneous product can thus be much thinner and therefore require less material, less transport, etc ... than a product having the same insulating properties but of poor homogeneity. To obtain at all points of the felt a mass per unit of surface at least equal to a value which one imposes oneself taking into account the quality of the final product sought, globally the quantity of fibers necessary can thus be from 15 to 20% , more important when the distribution is not satisfactory.

Les propriétés mécaniques des produits, en particulier vis-à-vis de la compression, sont aussi très sensiblement influencées par l'homogénéité de la distribution des fibres.The mechanical properties of the products, in particular with respect to compression, are also very significantly influenced by the homogeneity of the distribution of the fibers.

Il est donc particulièrement souhaitable d'obtenir un produit dans lequel les fibres sont bien uniformément distribuées. Un des aspects de cette distribution concerne la répartition transversalement au convoyeur. Il apparaît en effet très difficile d'obtenir dans les conditions traditionnelles un dépôt uniforme sur toute la largeur. Ordinairement on constate une densité de fibres plus forte sur les bords du feutre formé et un « creux au centre du feutre.It is therefore particularly desirable to obtain a product in which the fibers are well uniformly distributed. One aspect of this distribution concerns the transverse distribution to the conveyor. It appears in fact very difficult to obtain, under traditional conditions, a uniform deposit over the entire width. Ordinarily there is a higher density of fibers on the edges of the felt formed and a "hollow in the center of the felt.

Les raisons qui aboutissent à cette distribution transversale sont mal connues.The reasons leading to this transverse distribution are poorly understood.

Il est remarquable que l'effet est à l'opposé de ce que l'on observe pour les feutres formés avec des dispositifs tels que ceux décrits dans la publication FR-A-2 510 909. Dans le cas de ces dispositifs pour lesquels les fibres sont obtenues en centrifugeant le matériau à travers les orifices disposés sur la paroi périphérique d'un centrifugeur, on constate en effet un dépôt de fibres plus important au centre du convoyeur. Les comparaisons sont de toute façon difficiles à établir dans la mesure où, indépendamment des considérations relatives aux moyens pour former les fibres, la disposition générale de l'installation de fibrage est totalement différente. En particulier dans les techniques auxquelles se rapporte la publication antérieure citée, le courant gazeux est dirigé verticalement de haut en bas, et le convoyeur est disposé transversalement à la trajectoire de ce courant.It is remarkable that the effect is the opposite of what is observed for the felts formed with devices such as those described in the publication FR-A-2 510 909. In the case of these devices for which the fibers are obtained by centrifuging the material through the orifices arranged on the peripheral wall of a centrifuge, there is indeed a greater deposit of fibers in the center of the conveyor. Comparisons are in any case difficult to establish in so far as, independently of the considerations relating to the means for forming the fibers, the general arrangement of the fiberizing installation is totally different. In particular in the techniques to which the cited earlier publication relates, the gas stream is directed vertically from top to bottom, and the conveyor is arranged transversely to the path of this stream.

Il est possible d'émettre certaines hypothèses sur les causes de la distribution constatée. Parmi ces hypothèses, une des plus simples est la suivante :

  • Le courant gazeux d'étirage est envoyé suivant une direction sensiblement parallèle à l'axe de la ou des roues. Au contact de celles-ci et également des fibres, le courant gazeux serait modifié et prendrait une forme tourbillonnaire qui aurait tendance à projeter les fibres vers l'extérieur et donc vers les bords du convoyeur. La présence de parois latérales dans la chambre de réception, le long du convoyeur, constituerait un obstacle sur la trajectoire des fibres vers l'extérieur et aboutirait à une accumulation des fibres au pied de ces parois. Cette explication qui a le mérite de la simplicité, ne permet pas de rendre compte parfaitement des phénomènes observés.
It is possible to make certain assumptions about the causes of the observed distribution. Among these hypotheses, one of the simplest is the following:
  • The drawing gas stream is sent in a direction substantially parallel to the axis of the wheel or wheels. On contact with these and also with the fibers, the gas stream would be modified and take on a vortex shape which would tend to project the fibers outwards and therefore towards the edges of the conveyor. The presence of side walls in the receiving chamber, along the conveyor, would constitute an obstacle on the path of the fibers towards the outside and would lead to an accumulation of fibers at the foot of these walls. This explanation, which has the merit of simplicity, does not allow a perfect account of the phenomena observed.

Quoi qu'il en soit, la répartition des fibres sur le feutre préparé de façon traditionnelle, n'est pas satisfaisante. L'invention se propose d'améliorer cette répartition.In any case, the distribution of the fibers on the felt prepared in the traditional way is not satisfactory. The invention proposes to improve this distribution.

Il est apparu au cours des recherches effectuées par les inventeurs qu'il est possible d'obtenir une répartition sensiblement meilleure en effectuant un soufflage additionnel dans le sens de progression du courant gazeux portant les fibres, sur les côtés de ce courant, le long des parois bordant le convoyeur de réception.It appeared during research carried out by the inventors that it is possible to obtain a substantially better distribution by carrying out an additional blowing in the direction of progression of the gas stream carrying the fibers, on the sides of this stream, along the walls bordering the receiving conveyor.

Antérieurement, dans les techniques de formation de feutres telles que celle décrite dans la publication FR-A 2 510 909, il a été proposé d'améliorer la distribution des fibres dans le feutre en modifiant la trajectoire du courant gazeux. Dans ce cas l'utilisation des jets gazeux additionnels a pour but de faire en sorte que le courant gazeux portant les fibres couvre toute la largeur du convoyeur, ce qui est obtenu soit en modifiant la géométrie du courant gazeux porteur de fibres, par exemple de la façon décrite dans la publication FR-A-2 510 909 de la Demanderesse, ou en imprimant des impulsions qui dévient alternativement le courant de manière à lui faire balayer toute la largeur du convoyeur. Dans ce cas également l'utilisation de ces jets supplémentaires se caractérise par le fait que les jets sont émis à proximité immédiate de l'origine du courant portant les fibres pour que leur modification soit aussi efficace que possible. Autrement dit, l'émission des jets additionnels se situe dans la chambre de réception à distance du convoyeur.Previously, in the techniques for forming felts such as that described in the publication FR-A 2 510 909, it has been proposed to improve the distribution of the fibers in the felt by modifying the trajectory of the gas stream. In this case the use of additional gas jets aims to ensure that the gas stream carrying the fibers covers the entire width of the conveyor, which is obtained either by modifying the geometry of the gas stream carrying fibers, for example of as described in the publication FR-A-2 510 909 of the Applicant, or by printing pulses which alternately divert the current so as to make it sweep the entire width of the conveyor. In this case also the use of these additional jets is characterized in that the jets are emitted in the immediate vicinity of the origin of the current carrying the fibers so that their modification is as effective as possible. In other words, the emission of additional jets is located in the receiving chamber at a distance from the conveyor.

Les dispositions selon l'invention sont fondamentalement différentes. Tout d'abord la technique de fibrage et le type d'installation dans lesquels l'invention est mise en œuvre sont d'une autre nature comme nous l'avons indiqué précédemment, selon l'invention ensuite, les jets gazeux additionnels n'ont pas pour but d'épanouir le courant gazeux portant les fibres ou de faire varier sa direction périodiquement, enfin, toujours selon l'invention, l'émission des jets additionnels est localisée à proximité du convoyeur et non à l'origine du courant gazeux dans la chambre de réception.The arrangements according to the invention are fundamentally different. First of all, the fiber drawing technique and the type of installation in which the invention is implemented are of another nature, as we have indicated above, according to the invention then, the additional gaseous jets have no not intended to spread the gas stream carrying the fibers or to vary its direction periodically, finally, still according to the invention, the emission of the additional jets is located near the conveyor and not at the origin of the gas stream in the reception room.

Les caractéristiques des jets additionnels doivent bien entendu être réglées en fonction de nombreux éléments spécifiques à chaque installation. Certains points sont cependant communs à toutes les réalisations.The characteristics of the additional jets must of course be adjusted according to many elements specific to each installation. Certain points are however common to all the achievements.

Ainsi les jets émis peuvent être très énergétiques, autrement dit ils peuvent être émis sous forte pression,, mais on constate expérimentalement que des jets à faible pression permettent aussi d'obtenir des résultats très satisfaisants et à moindre coût. Ceci confirme les différences de modalité d'action des jets selon l'invention par rapport aux jets utilisés dans d'autres techniques, pour influencer la répartition des fibres. La modification de la trajectoire du courant gazeux porteur de fibres, dans ces techniques, requiert une dépense énergétique relativement forte ce qui n'est pas le cas de l'invention.Thus the jets emitted can be very energetic, in other words they can be emitted under high pressure, but it has been found experimentally that jets at low pressure also make it possible to obtain very satisfactory results and at lower cost. This confirms the differences in the mode of action of the jets according to the invention compared to the jets used in other techniques, to influence the distribution of the fibers. The modification of the trajectory of the gaseous current carrying fibers, in these techniques, requires a relatively high energy expenditure which is not the case of the invention.

Il est important également que l'émission des jets additionnels ait lieu le long des parois latérales bordant le convoyeur, autrement dit sensiblement dans la direction de propagation du courant portant les fibres. Lorsque la direction du courant gazeux doit être modifiée, comme c'est le cas dans les techniques dont il a été question plus haut, les jets sont dirigés vers le courant transversalement à sa trajectoire, perpendiculairement sinon suivant un angle prononcé avec cette trajectoire. L'expérience montre que selon l'invention, au contraire, lorsque l'angle des jets additionnels avec la direction des courants gazeux portant les fibres, ou celui avec les parois latérales de la chambre de réception ce qui est équivalent, est trop important l'effet de ces jets sur la distribution décroît et peut même s'annuler. Pour cette raison, l'angle des jets avec les parois est avantageusement inférieur à 20°. Dans la pratique, il est préférable de diriger les jets parallèlement aux parois et également suivant une direction parallèle au convoyeur.It is also important that the emission of the additional jets takes place along the side walls bordering the conveyor, in other words substantially in the direction of propagation of the current carrying the fibers. When the direction of the gas stream must be changed, as is the case in the techniques mentioned above, the jets are directed towards the stream transverse to its trajectory, perpendicularly if not at a pronounced angle with this trajectory. Experience shows that, according to the invention, on the contrary, when the angle of the additional jets with the direction of the gas streams carrying the fibers, or that with the side walls of the receiving chamber, which is equivalent, is too large l The effect of these jets on the distribution decreases and can even cancel out. For this reason, the angle of the jets with the walls is advantageously less than 20 °. In practice, it is preferable to direct the jets parallel to the walls and also in a direction parallel to the conveyor.

L'énergie communiquée aux jets additionnels est relativement faible. Nous avons vu que la pression du jet à l'orifice n'a pas besoin d'être élevée. Le volume de gaz nécessaire est également relativement faible par rapport à la masse de gaz véhiculant les fibres qui est aspirée sous le convoyeur. Cette quantité de gaz soufflée est réglée en fonction de l'intensité de l'effet à obtenir. De façon simplifiée, on peut considérer, dans certaines limites, que l'effet est d'autant plus marqué que la quantité soufflée est plus importante.The energy communicated to the additional jets is relatively low. We have seen that the pressure from the jet to the orifice does not need to be high. The volume of gas required is also relatively small compared to the mass of gas carrying the fibers which is sucked under the conveyor. This quantity of blown gas is adjusted according to the intensity of the effect to be obtained. In a simplified manner, it can be considered, within certain limits, that the effect is all the more marked the greater the quantity blown.

Il ne faut cependant pas que la quantité soufflée soit trop importante car alors on constate que l'effet diminue et peut aller jusqu'à s'annuler. Des essais simples permettent de déterminer dans chaque cas les limites utiles.However, the quantity blown must not be too large because then it is observed that the effect decreases and can go as far as canceling out. Simple tests make it possible to determine the useful limits in each case.

Expérimentalement, on constate que pour rétablir une répartition satisfaisante des fibres, la masse de gaz additionnels qu'il est nécessaire de souffler ne représente habituellement pas plus de 2 à 3 % de la masse totale des gaz aspirés sous le convoyeur.Experimentally, it can be seen that to restore a satisfactory distribution of the fibers, the mass of additional gases which it is necessary to blow does not usually represent more than 2 to 3% of the total mass of the gases sucked under the conveyor.

Les conditions d'émission sont telles que les jets gazeux ont une vitesse de l'ordre de celle des courants gazeux, au même niveau, ou sensiblement plus grande.The emission conditions are such that the gas jets have a speed of the order of that of the gas streams, at the same level, or substantially greater.

Les jets additionnels sont émis le long du courant gazeux. Il n'est pas nécessaire qu'ils couvrent toute la hauteur des parois latérales. Leur localisation au niveau moyen du flux gazeux portant les fibres est suffisant. Eventuellement, ces jets additionnels peuvent avantageusement être légèrement décalés vers le convoyeur. Le soufflage ne doit pas cependant être effectué le long du convoyeur ce qui pourrait conduire à balayer complètement les fibres qui se déposent. De préférence on laisse une distance minimum de 0,3 m entre le convoyeur et le point d'émission le plus proche du convoyeur.The additional jets are emitted along the gas stream. They do not need to cover the entire height of the side walls. Their location at the mean level of the gas flow carrying the fibers is sufficient. Optionally, these additional jets can advantageously be slightly offset towards the conveyor. The blowing should not however be carried out along the conveyor which could lead to completely sweeping the fibers which are deposited. Preferably a minimum distance of 0.3 m is left between the conveyor and the point of emission closest to the conveyor.

Le mécanisme qui aboutit par soufflage selon l'invention à mieux alimenter le centre du convoyeur et à diminuer en conséquence la masse de fibres par unité de surface sur les côtés, n'est pas mieux élucidé que la raison de la distribution irrégulière qui est constatée en l'absence de l'invention. Lorsque l'on considère la façon dont l'accumulation de fibres sur le convoyeur se développe d'une extrémité à l'autre de la chambre de réception, la seule conclusion que l'on peut tirer est que le mécanisme en présence duquel on se trouve est un ensemble complexe qui n'est pas réductible à un effet unique. Nous verrons ceci dans l'étude des exemples.The mechanism which leads by blowing according to the invention to better feed the center of the conveyor and to consequently decrease the mass of fibers per unit of area on the sides, is not better understood than the reason for the irregular distribution which is observed. in the absence of the invention. When we consider how the accumulation of fibers on the conveyor develops from one end to the other of the receiving chamber, the only conclusion that we can draw is that the mechanism in the presence of which we are finds is a complex whole which cannot be reduced to a single effect. We will see this in the study of examples.

L'invention est décrite plus en détail dans la suite de la description en se référant aux planches de dessins dans lesquelles :

  • la figure 1 est une vue schématique en perspective de la partie d'une installation dans laquelle les fibres sont produites puis recueillies pour former le feutre,
  • la figure 2 est une vue de côté analogue à la figure 1, dans laquelle les parois en façade de l'installation sont enlevées pour montrer la trajectoire des fibres et leur dépôt sur le convoyeur,
  • la figure 3 montre schématiquement le mode de distribution des fibres dans le feutre sur une coupe transversale en l'absence de l'invention,
  • la figure 4 montre en vue de dessus la disposition de jets additionnels dans des conditions ne répondant pas à l'invention,
  • la figure 5 est une vue détaillée d'un mode de réalisation du dispositif de soufflage additionnel selon l'invention,
  • la figure 6 est une vue d'un autre mode de réalisation de l'invention,
  • la figure 7 est une vue de dessus du dispositif de la figure 6,
  • la figure 8 montre schématiquement les quatre types de répartitions servant de base pour caractériser les répartitions effectivement observées,
  • la figure 9 est un graphique montrant l'influence de la pression de soufflage selon l'invention sur un paramètre de mesure de la distribution,
  • la figure 10 présente l'influence de la pression de soufflage selon l'invention sur un autre paramètre de mesure de la distribution.
The invention is described in more detail in the following description with reference to the drawing boards in which:
  • FIG. 1 is a schematic perspective view of the part of an installation in which the fibers are produced and then collected to form the felt,
  • FIG. 2 is a side view similar to FIG. 1, in which the front walls of the installation are removed to show the path of the fibers and their deposition on the conveyor,
  • FIG. 3 schematically shows the mode of distribution of the fibers in the felt on a cross section in the absence of the invention,
  • FIG. 4 shows a top view of the arrangement of additional jets under conditions which do not correspond to the invention,
  • FIG. 5 is a detailed view of an embodiment of the additional blowing device according to the invention,
  • FIG. 6 is a view of another embodiment of the invention,
  • FIG. 7 is a top view of the device of FIG. 6,
  • FIG. 8 schematically shows the four types of distributions serving as a basis for characterizing the distributions actually observed,
  • FIG. 9 is a graph showing the influence of the blowing pressure according to the invention on a parameter for measuring the distribution,
  • FIG. 10 shows the influence of the blowing pressure according to the invention on another parameter for measuring the distribution.

La partie de l'installation représentée à la figure 1 comprend essentiellement le dispositif de formation des fibres et la chambre de réception dans laquelle se forme le feutre.The part of the installation shown in FIG. 1 essentially comprises the device for forming the fibers and the receiving chamber in which the felt is formed.

Le dispositif de formation des fibres est constitué par un ensemble de trois roues 1, 2, 3 tournant en sens inverse les unes des autres, et des couronnes 4, 5 engendrant un courant gazeux à la périphérie des roues de fibrage.The fiber-forming device consists of a set of three wheels 1, 2, 3 rotating in opposite directions to each other, and rings 4, 5 generating a gas stream at the periphery of the fiberizing wheels.

L'alimentation en matériau est assurée à partir d'un four ou d'un creuset 6. Le matériau s'écoule par une goulotte 7 sur la première roue 1 dite roue de distribution parce que son rôle principal est d'accélérer le matériau et que peu de fibres s'en détachent.The material is supplied from an oven or a crucible 6. The material flows through a chute 7 onto the first wheel 1 called the distribution wheel because its main role is to accelerate the material and that few fibers detach from it.

Le matériau accéléré au contact de la roue 1 est projeté sur la roue 2. Une partie du matériau adhère à cette roue puis, sous l'effet de la centrifugation, est projetée sous forme de fins filaments. L'autre partie du matériau est renvoyée sur la roue 3 où elle adhère et forme des filaments de la même façon que pour la roue 2.The material accelerated in contact with the wheel 1 is sprayed onto the wheel 2. Part of the material adheres to this wheel then, under the effect of centrifugation, is sprayed in the form of fine filaments. The other part of the material is returned to the wheel 3 where it adheres and forms filaments in the same way as for the wheel 2.

Les filaments qui se détachent des roues sont entraînés (et étirés lorsqu'ils sont dans des conditions convenables) par un courant gazeux soufflé à partir des couronnes de soufflage 4 et 5 qui entourent les roues d'où se détachent les fibres.The filaments which detach from the wheels are entrained (and drawn when they are in suitable conditions) by a gas stream blown from the blowing rings 4 and 5 which surround the wheels from which the fibers detach.

Eventuellement une couronne supplémentaire peut entourer, au moins partiellement, la roue 1 lorsque celle-ci se trouve à même de produire également des fibres.Optionally, an additional crown can surround, at least partially, the wheel 1 when the latter is also able to produce fibers.

Le dispositif représenté est typique d'une installation pour la formation de fibres minérales, notamment pour les matériaux dont la température de fusion est particulièrement élevée : roche basaltique, laitier de fonderie, etc... Des installations analogues comprenant des dispositifs de centrifugation à une, deux ou quatre roues sont également couramment utilisées pour ce genre de production.The device shown is typical of an installation for the formation of mineral fibers, in particular for materials whose melting temperature is particularly high: rock basalt, foundry slag, etc ... Similar installations including centrifugal devices with one, two or four wheels are also commonly used for this kind of production.

Des moyens sont normalement disposés au voisinage des roues, ou sur les roues elles-mêmes, pour projeter une composition d'un liant sur les fibres entraînées par le courant gazeux. Ces moyens ne sont pas représentés.Means are normally arranged in the vicinity of the wheels, or on the wheels themselves, for spraying a composition of a binder on the fibers entrained by the gas stream. These means are not shown.

Sous le dispositif de centrifugation et en avant, se trouve une trémie 8 qui recueille les particules infibrées projetées directement à partir du dispositif de centrifugation, où celles qui, parce qu'elles sont trop denses, « sédimentent avant d'atteindre le convoyeur de réception 9.Under the centrifuge device and in front there is a hopper 8 which collects the infibrated particles projected directly from the centrifuge device, where those which, because they are too dense, "sediment before reaching the receiving conveyor 9.

La distance horizontale séparant le dispositif de formation des fibres du convoyeur 9 est de l'ordre de 2 à 3 m, ce qui permet une élimination relativement importante d'infibrés ou de particules insuffisamment fibrées.The horizontal distance separating the fiber-forming device from the conveyor 9 is of the order of 2 to 3 m, which allows a relatively large elimination of fiber particles or insufficiently fiber particles.

La chambre de réception dans laquelle circulent les fibres et les courants gazeux qui les portent est pratiquement close. Les seules ouvertures permettant l'introduction d'une quantité significative d'air extérieur se situent derrière l'appareil de centrifugation et au niveau de la trémie 8. Ces ouvertures et l'air induit qu'elles laissent entrer facilitent le bon développement du flux gazeux dans la chambre de réception.The receiving chamber in which the fibers and the gas streams carrying them circulate is practically closed. The only openings allowing the introduction of a significant quantity of outside air are located behind the centrifuge and at the level of the hopper 8. These openings and the induced air which they allow to enter facilitate the good development of the flow gas in the reception room.

Cette chambre de réception est fermée à sa base par le convoyeur 9 et latéralement, le long du convoyeur, par des parois 10 et 11.This receiving chamber is closed at its base by the conveyor 9 and laterally, along the conveyor, by walls 10 and 11.

Pour des raisons, notamment de commodité d'entretien, les parois 10 et 11 sont avantageusement mobiles en rotation et se déplacent dans le même sens que le convoyeur 9.For reasons, in particular of convenience of maintenance, the walls 10 and 11 are advantageously movable in rotation and move in the same direction as the conveyor 9.

Entre la partie de la chambre délimitée par le convoyeur et les parois latérales mobiles, et l'extrémité portant le dispositif de centrifugation la continuité est assurée par des parois 15, 16 métalliques fixes, qui doivent être très résistantes en raison des projections d'infibrés qui les frappent. Des volets de matériau souple non représentés sont fixés aux extrémités des parois 15 et 16. Ces volets qui viennent s'appliquer sur les parois mobiles 10 et 11 assurent l'étanchéité à ce niveau.Between the part of the chamber delimited by the conveyor and the movable side walls, and the end carrying the centrifugation device, continuity is ensured by fixed metal walls 15, 16, which must be very resistant due to the projections of infibers hitting them. Flaps of flexible material, not shown, are fixed to the ends of the walls 15 and 16. These flaps which are applied to the movable walls 10 and 11 provide sealing at this level.

La chambre est également close à sa partie supérieure ce qui n'est pas représenté sur la figure 1, pour des raisons de clarté.The chamber is also closed at its upper part which is not shown in Figure 1, for reasons of clarity.

Des caissons d'aspiration 12 et 13 sont disposés sous le convoyeur 9 sur toute la longueur. Ces caissons qui sont maintenus en dépression par rapport à la chambre de réception évacuent les gaz porteurs des fibres, après que celles-ci aient été retenues sur le convoyeur.Suction boxes 12 and 13 are arranged under the conveyor 9 over the entire length. These boxes which are kept in depression with respect to the receiving chamber evacuate the gases carrying the fibers, after these have been retained on the conveyor.

La figure 2 montre de façon approximative la trajectoire suivie par les gaz et les fibres.Figure 2 roughly shows the path followed by the gases and fibers.

Le mouvement des courants gazeux circulant dans la chambre de réception est commandé par les gaz d'étirage émis le long des roues de centrifugation. Il est commandé par l'aspiration maintenue sous le convoyeur de réception. S'ajoutent à ces effets ceux qui résultent de l'induction d'air ambiant.The movement of the gas streams flowing in the receiving chamber is controlled by the drawing gases emitted along the centrifuge wheels. It is controlled by the suction maintained under the receiving conveyor. Added to these effects are those which result from the induction of ambient air.

La quantité de gaz franchissant le convoyeur 9 est très supérieure à celle émise par les couronnes de soufflage 4 et 5. Pour la majeure partie, le gaz aspiré dans les caissons 12 et 13 pénètre dans la chambre de réception par des ouvertures ménagées pour laisser pénétrer l'air « induit ». Les ouvertures en question sont situées principalement au niveau de la trémie 8 et sur la paroi de la chambre sur laquelle se trouve le dispositif de fibrage.The amount of gas passing through the conveyor 9 is much greater than that emitted by the blowing rings 4 and 5. For the most part, the gas sucked into the boxes 12 and 13 enters the receiving chamber through openings made to allow entry "induced" air. The openings in question are located mainly at the level of the hopper 8 and on the wall of the chamber on which the fiberizing device is located.

Les flèches I schématisent les grandes lignes de courant de l'air induit.The arrows I represent the main lines of the induced air flow.

La circulation de l'air induit dans la trémie 8 se fait à contre courant des particules projetées à partir des roues de centrifugation. Ce mouvement permet de compléter l'effet de tri recherché pour séparer les fibres des particules infibrées.The circulation of the air induced in the hopper 8 is done against the current of the particles projected from the centrifuge wheels. This movement makes it possible to complete the sorting effect sought to separate the fibers from the infibrated particles.

Dans l'ensemble, les fibres se déplacent dans la chambre de réception suivant une direction voisine de l'horizontale. Cette direction s'infléchit vers le convoyeur de réception sous l'effet de l'aspiration. Elles se déposent progressivement sur le convoyeur 9 pour former le feutre 14 dont l'épaisseur s'accroît jusqu'à la sortie de la chambre.Overall, the fibers move in the reception chamber in a direction close to the horizontal. This direction bends towards the receiving conveyor under the effect of suction. They are gradually deposited on the conveyor 9 to form the felt 14, the thickness of which increases until it leaves the chamber.

La circulation des gaz dans la chambre est très turbulente, aussi il n'est pas possible de représenter une trajectoire précise mais seulement le mouvement global.The circulation of gases in the chamber is very turbulent, so it is not possible to represent a precise trajectory but only the overall movement.

La distribution des fibres que l'on obtient en l'absence de mise en œuvre de l'invention est du type représenté à la figure 3. Deux défauts sont ordinairement observés, un creux au milieu du feutre, ou ce qui est équivalent un excès de fibres sur les bords, et un déséquilibre d'un côté par rapport à l'autre.The distribution of the fibers that is obtained in the absence of implementation of the invention is of the type shown in Figure 3. Two defects are usually observed, a hollow in the middle of the felt, or what is equivalent an excess of fibers on the edges, and an imbalance on one side compared to the other.

Une analyse plus détaillée de la façon dont les fibres se déposent le long du convoyeur montre la complexité du phénomène. Dans leurs études, les inventeurs ont constaté en effet qu'au début, c'est-à-dire sur la partie du convoyeur proche du dispositif de formation des fibres, le dépôt est plus abondant au centre que sur les bords et que la tendance s'inverse progressivement au fur et à mesure que la formation du feutre se poursuit jusqu'à l'autre extrémité de la chambre de réception.A more detailed analysis of how the fibers settle along the conveyor shows the complexity of the phenomenon. In their studies, the inventors have indeed found that at the beginning, that is to say on the part of the conveyor close to the fiber-forming device, the deposit is more abundant in the center than on the edges and that the tendency gradually reverses as the formation of the felt continues to the other end of the receiving chamber.

Il est remarquable de constater que les tentatives dans le but de modifier la trajectoire du courant portant les fibres, n'ont pas permis de remédier à ces défauts de répartition. Les inventeurs ont essayé en particulier, sans succès, de modifier ce courant au moyen de jets gazeux dirigés transversalement à la trajectoire générale des fibres à proximité du dispositif de fibrage. La direction des jets additionnels était celle schématisée à la figure 4. Dans cette disposition, et pour des débits gazeux comparables à ceux mis en oeuvre selon la présente invention, il n'a pas été possible d'obtenir une modification satisfaisante de la répartition des fibres.It is remarkable to note that the attempts in order to modify the trajectory of the current carrying the fibers, have not made it possible to remedy these distribution defects. The inventors have tried in particular, without success, to modify this current by means of gas jets directed transversely to the general path of the fibers near the fiberizing device. The direction of the additional jets was that shown diagrammatically in FIG. 4. In this arrangement, and for gas flows comparable to those used according to the present invention, it was not possible to obtain a satisfactory modification of the distribution of the fibers.

De façon surprenante, les inventeurs ont constaté au contraire qu'en soufflant le long des parois latérales 10 et 11 des quantités relativement faibles de gaz, une modification substantielle de la distribution était possible.Surprisingly, the inventors have found, on the contrary, that by blowing along the walls side 10 and 11 relatively small amounts of gas, a substantial change in distribution was possible.

La figure 5 reprend à plus grande échelle une partie de la figure 1 sur laquelle est représenté un mode de réalisation de l'invention. Suivant ce mode, des tuyères de soufflage 18 conduisent de l'air sous pression à des buses de soufflage 19 disposées à la limite entre les cloisons 16 et 11.Figure 5 shows on a larger scale a part of Figure 1 on which is shown an embodiment of the invention. According to this mode, blowing nozzles 18 conduct air under pressure to blowing nozzles 19 arranged at the limit between the partitions 16 and 11.

Un espace minimum est toujours ménagé à cet emplacement pour ne pas gêner le mouvement de la cloison 11. Cet espacement est suffisant pour passer les buses dont l'extrémité, constituant l'orifice émetteur 20, est aplatie pour former des jets plans. Le volet d'étanchéité comme à la figure 1 n'est pas représenté.A minimum space is always provided at this location so as not to hinder the movement of the partition 11. This spacing is sufficient to pass the nozzles, the end of which, constituting the emitter orifice 20, is flattened to form flat jets. The sealing flap as in Figure 1 is not shown.

La figure ne présente qu'un côté du dispositif. Il va de soi que des tuyères analogues sont disposées également pour souffler à la limite entre les parois 15 et 10.The figure shows only one side of the device. It goes without saying that similar nozzles are also arranged to blow at the limit between the walls 15 and 10.

L'axe des buses de soufflage est sensiblement parallèle à la paroi mobile 11 de façon que les jets émis longent cette paroi.The axis of the blowing nozzles is substantially parallel to the movable wall 11 so that the emitted jets run along this wall.

Sur la figure 5, cinq buses distinctes conduisent le gaz additionnel à différents niveaux le long de la paroi 11. D'autres dispositions sont utilisables sans modifier le fonctionnement d'ensemble. Il est possible notamment de souffler à partir d'un orifice unique, de préférence suffisamment allongé, pour répartir le gaz soufflé sur une certaine hauteur. C'est le cas pour le dispositif représenté à la figure 6.In FIG. 5, five separate nozzles conduct the additional gas at different levels along the wall 11. Other arrangements can be used without modifying the overall operation. It is possible in particular to blow from a single orifice, preferably sufficiently elongated, to distribute the blown gas over a certain height. This is the case for the device represented in FIG. 6.

Sur cette figure, le gaz amené par la tuyère 21 est émis par la buse unique 22. Le soufflage est effectué légèrement en dessous de la trajectoire moyenne des fibres déterminée à leur origine par la position des roues de centrifugation, et à une certaine distance du convoyeur 9.In this figure, the gas supplied by the nozzle 21 is emitted by the single nozzle 22. The blowing is carried out slightly below the average path of the fibers determined at their origin by the position of the centrifugation wheels, and at a certain distance from the conveyor 9.

La position verticale des souffleurs peut varier dans certaines limites. Des essais permettent de déterminer dans chaque cas la meilleure position, c'est-à-dire celle qui permet d'obtenir la modification la plus grande pour un jet additionnel dont les autres caractéristiques sont maintenues constantes.The vertical position of the blowers can vary within certain limits. Tests make it possible to determine in each case the best position, that is to say the one which makes it possible to obtain the greatest modification for an additional jet whose other characteristics are kept constant.

Il est très important de bien conserver la direction des jets. Si l'on fait pivoter les buses de sorte que le jet s'écarte de la paroi on constate très vite une diminution de l'influence sur la répartition.It is very important to keep the direction of the jets. If the nozzles are rotated so that the jet moves away from the wall, there is very quickly a reduction in the influence on the distribution.

La figure 7 montre la position des buses et la direction des jets émis. Les buses sont placées le long des parois 15 et 16 et à l'extrémité de celles-ci légèrement en avant vis-à-vis des parois tournantes, l'extrémité de la buse pratiquement au niveau où la paroi devient plane. Dans cette position, les jets pénètrent dans la chambre de réception immédiatement après leur émission, ce qui leur confère un maximum d'efficacité.Figure 7 shows the position of the nozzles and the direction of the jets emitted. The nozzles are placed along the walls 15 and 16 and at the end thereof slightly forward with respect to the rotating walls, the end of the nozzle practically at the level where the wall becomes planar. In this position, the jets enter the reception chamber immediately after their emission, which gives them maximum efficiency.

Les buses peuvent aussi s'avancer davantage à l'intérieur de la chambre de réception. Il ne semble pas que ceci procure des améliorations supplémentaires. En effet la buse qui doit se supporter elle-même ne pénètre pas très loin dans la chambre. Par ailleurs, si la buse devait s'avancer davantage, elle constituerait un point particulier le long de la paroi, sur lequel les fibres pourraient venir s'accrocher ce qui n'est pas souhaitable.The nozzles can also extend further inside the receiving chamber. This does not appear to provide further improvements. In fact, the nozzle which must support itself does not penetrate very far into the chamber. Furthermore, if the nozzle were to advance further, it would constitute a particular point along the wall, on which the fibers could come to hang which is not desirable.

Des essais ont été conduits avec des pressions très variables de 0,1 à 4 bars. La pression la mieux adaptée pour chaque cas dépend des buses de soufflage. En effet, les résultats, comme nous le verrons dans ce qui suit, dépendent de la masse de gaz soufflée et par suite lorsque les buses offrent des orifices de petite dimension il est nécessaire d'utiliser une pression plus élevée.Tests were carried out with very variable pressures from 0.1 to 4 bars. The most suitable pressure for each case depends on the blowing nozzles. Indeed, the results, as we will see in the following, depend on the mass of gas blown and therefore when the nozzles offer small orifices it is necessary to use a higher pressure.

En pratique, il semble avantageux d'opérer à faible pression éventuellement en accroissant les dimensions des orifices d'émission. Le coût de production de tels jets est moindre. Par ailleurs l'utilisation des jets plus larges assure une action mieux répartie sur les courants gazeux circulant dans la chambre de réception.In practice, it seems advantageous to operate at low pressure, possibly by increasing the dimensions of the emission orifices. The cost of producing such jets is lower. Furthermore, the use of larger jets ensures a better distributed action on the gas streams circulating in the receiving chamber.

A titre d'exemple, figurent ci-après des résultats d'essais selon l'invention pour améliorer la répartition transversale de fibres formant un feutre. Les essais sont conduits dans une installation du type présenté à la figure 1.By way of example, the following are test results according to the invention for improving the transverse distribution of fibers forming a felt. The tests are carried out in an installation of the type presented in FIG. 1.

Les souffleurs additionnels utilisés comprennent sur chaque côté de l'installation une seule buse de soufflage. Ces buses analogues à celle présentée à la figure 6 ont un orifice allongé sur 500 mm pour une largeur de 25 mm.The additional blowers used include a single blowing nozzle on each side of the installation. These nozzles similar to that presented in FIG. 6 have an orifice extended over 500 mm for a width of 25 mm.

Les souffleurs sont alimentés par un ventilateur à basse pression. Ils sont réglés indépendamment l'un de l'autre par deux vannes distinctes.The blowers are powered by a low pressure fan. They are regulated independently of each other by two separate valves.

La répartition des fibres est mesurée au moyen d'une sonde à rayons X. Cette sonde est mobile et se déplace transversalement au convoyeur. Elle opère sur le feutre sortant de la chambre de réception.The distribution of the fibers is measured by means of an X-ray probe. This probe is mobile and moves transversely to the conveyor. It operates on the felt leaving the reception room.

L'analyse des mesures de densité de fibres par absorption des rayons X est faite en distinguant trois zones sur le feutre : une zone centrale et deux zones latérales. Ces trois zones sont de même largeur.The analysis of fiber density measurements by absorption of X-rays is made by distinguishing three zones on the felt: a central zone and two lateral zones. These three zones are the same width.

La répartition est représentée par deux valeurs, un « taux de creux y qui exprime le déséquilibre de répartition entre le centre et les bords du feutre, et un taux de « pente montrant le déséquilibre entre les deux bords.The distribution is represented by two values, a "trough rate y which expresses the distribution imbalance between the center and the edges of the felt, and a" slope rate showing the imbalance between the two edges.

Si l'on désigne par A, B et C les mesures correspondant respectivement aux masses de fibres par unité de surface sur un côté, le centre et l'autre côté du feutre, le taux de creux est déterminé selon la formule :

Figure imgb0001
et le taux de pente :
Figure imgb0002
 If we denote by A, B and C the measurements corresponding respectively to the masses of fibers per unit area on one side, the center and the other side of the felt, the hollow ratio is determined according to the formula:
Figure imgb0001
 and the slope rate:
Figure imgb0002

Lorsque X est positif la densité en fibre est plus faible au centre que sur les bords.When X is positive the fiber density is lower in the center than at the edges.

La figure 8 montre schématiquement, suivant les valeurs des taux de creux et de pente, la forme générale de la répartition des fibres transversalement au convoyeur. En pratique, il faut bien entendu combiner une forme représentant le taux de creux et celle correspondant au taux de pente.FIG. 8 schematically shows, according to the values of the trough and slope rates, the general shape of the distribution of the fibers transversely to the conveyor. In practice, it is of course necessary to combine a form representing the trough rate and that corresponding to the slope rate.

Dans une première série d'essais, un produit est préparé à raison de 6 tonnes par heure. Le feutre formé présente une masse par unité de surface moyenne de 5,5 kg/m2. Le taux de liant est de 6,6 % de la masse du feutre,In a first series of tests, a product is prepared at the rate of 6 tonnes per hour. The felt formed has a mass per unit surface area of 5.5 kg / m 2 . The binder rate is 6.6% of the mass of the felt,

La quantité moyenne de gaz aspirée sous le convoyeur est de l'ordre de 175 000 Nm3/h.The average quantity of gas sucked under the conveyor is around 175,000 Nm 3 / h.

Les quantités de gaz soufflé le long des parois sont modifiées et l'on suit l'évolution des taux de pente et de creux.The quantities of gas blown along the walls are modified and the trend in slope and trough rates is monitored.

Les résultats sont regroupés dans le tableau I en annexe.The results are collated in Table I in the appendix.

La répartition initiale est mauvaise comme on le constate à l'exemple 1. Les taux de creux et de pente sont tous les deux relativement élevés, alors que pour une répartition idéale ils doivent tendre à s'annuler l'un et l'autre.The initial distribution is poor, as can be seen in example 1. The trough and slope rates are both relatively high, while for an ideal distribution they must tend to cancel each other out.

Dans une répartition de ce type, c'est-à-dire sans mise en oeuvre de l'invention, la quantité de fibres nécessaire pour atteindre en tout point du feutre la densité requise se trouve sensiblement accrue. Le fonctionnement n'est pas satisfaisant.In a distribution of this type, that is to say without implementation of the invention, the quantity of fibers necessary to reach the required density at any point of the felt is significantly increased. The operation is not satisfactory.

Les exemples 2 à 6 sont conduits en faisant souffler les buses selon l'invention à différentes pressions.Examples 2 to 6 are carried out by blowing the nozzles according to the invention at different pressures.

On remarque que par suite de configurations différentes dans le circuit entre la droite et la gauche, pour une même pression les débits ne sont pas identiques. Ceci ne constitue pas un obstacle au bon fonctionnement dans la mesure où le réglage de chaque buse est effectué séparément.It is noted that as a result of different configurations in the circuit between the right and the left, for the same pressure the flow rates are not identical. This does not constitute an obstacle to proper operation since the adjustment of each nozzle is carried out separately.

Les exemples 2, 3, 4 et 5 montrent la progressivité des effets obtenus en accroissant la pression simultanément sur les deux buses. Les taux de creux et de pente sont sensiblement réduits. Le taux de creux devient même négatif.Examples 2, 3, 4 and 5 show the progressiveness of the effects obtained by increasing the pressure simultaneously on the two nozzles. The trough and slope rates are significantly reduced. The trough rate even becomes negative.

L'exemple 6 (qui ne correspond pas à une distribution satisfaisante), est réalisé pour montrer l'influence de l'utilisation de deux pressions différentes. On constate que la différence dans le soufflage permet de modifier profondément le taux de pente. On dispose donc par ce biais de moyens pour faire varier de façon partiellement indépendante le taux de creux et le taux de pente.Example 6 (which does not correspond to a satisfactory distribution), is carried out to show the influence of the use of two different pressures. It is noted that the difference in the blowing makes it possible to modify the slope rate profoundly. Means are therefore available through this means for varying the dip rate and the slope rate in a partially independent manner.

Il va de soi que la répartition des fibres sur le convoyeur est sensible à de nombreux facteurs et, en particulier, aux caractéristiques du produit préparé.It goes without saying that the distribution of the fibers on the conveyor is sensitive to many factors and, in particular, to the characteristics of the product prepared.

Des essais analogues aux précédents ont été effectués au cours de la préparation d'un feutre présentant d'autres caractéristiques. Il s'agit d'un feutre dont la masse par unité de surface est de 5,2 kg/m2. Le taux de liant est ici de 2.4 %.Tests similar to the previous ones were carried out during the preparation of a felt having other characteristics. It is a felt whose mass per unit area is 5.2 kg / m 2. The binder rate here is 2.4%.

Les résultats, analogues aux précédents, sont regroupés dans le tableau Il en annexe.The results, similar to the previous ones, are grouped in Table II in the appendix.

Dans ces essais, la progressivité des effets obtenus est confirmée. On ne s'est pas efforcé d'équilibrer les deux bords du feutre. Les pressions sont identiques des deux côtés. On voit cependant que pour obtenir une meilleure répartition, il est nécessaire d'avoir des conditions différentes dans le soufflage à droite et à gauche.In these tests, the progressiveness of the effects obtained is confirmed. No attempt has been made to balance the two edges of the felt. The pressures are identical on both sides. It can be seen, however, that in order to obtain a better distribution, it is necessary to have different conditions in the right and left blowing.

Les résultats précédents sont présentés graphiquement aux figures 9 et 10.The previous results are presented graphically in Figures 9 and 10.

Sur ces figures, sont reportés respectivement les taux de creux (figure 9) et de pente (figure 10) pour les deux séries d'essais précédents (I et II).In these figures, the trough (figure 9) and slope (figure 10) rates are reported respectively for the two previous series of tests (I and II).

Il est remarquable de constater que dans les limites des conditions expérimentales utilisées, les modifications sont pratiquement linéaires. Indépendamment de l'allure de la réponse, ce qui est important, et que nous avons déjà souligné, c'est la progressivité de l'effet qui permet le réglage de l'installation pour aboutir à une distribution très régulière.It is remarkable to note that within the limits of the experimental conditions used, the modifications are practically linear. Regardless of the appearance of the response, which is important, and which we have already underlined, it is the progressiveness of the effect which allows the adjustment of the installation to result in a very regular distribution.

Par ailleurs, les dispositifs de soufflage selon l'invention peuvent être mis en oeuvre de façon automatique.Furthermore, the blowing devices according to the invention can be implemented automatically.

La régulation se fait dans ce cas en continu à partir des mesures provenant de la sonde d'absorption des rayons X. Les valeurs mesurées sont traitées par l'intermédiaire d'un calculateur pour aboutir par exemple aux expressions de taux de creux et de pente. Un algorithme mis en mémoire élabore à partir de ces résultats une réponse qui correspond à une modification des flux soufflés par les buses selon l'invention au moyen des vannes disposées sur les tuyères.The regulation is done in this case continuously from the measurements coming from the X-ray absorption probe. The measured values are processed by means of a computer to arrive, for example, at the expressions of dip rate and slope . An algorithm stored in memory elaborates from these results a response which corresponds to a modification of the flows blown by the nozzles according to the invention by means of the valves arranged on the nozzles.

La possibilité de faire varier le débit gazeux de façon continue permet un réglage parfaitement adapté à toutes les situations rencontrées en pratique.
(Voir tableaux I et Il page 8)

Figure imgb0003
Figure imgb0004
 The possibility of varying the gas flow continuously allows an adjustment perfectly suited to all situations encountered in practice.
(See tables I and II on page 8)
Figure imgb0003
Figure imgb0004

Claims (11)

1. A method of forming a felt of fibres in which the fibres are formed from a material which is in the drawable state, this material being carried over the peripheral surface of one or more wheels to which a rotary movement is imparted and from which the fibres become detached and are thrown into a gaseous current which is directed transversely of the direction in which the fibres are thrown and along the peripheral wall of the wheel or wheels, the fibres thus formed, entrained by the gaseous current, being carried into a receiving chamber in which the base is constituted by a perforated conveyor, the gaseous current carrying the fibres crossing the conveyor, the fibres becoming deposited on the conveyor in order to form the felt, the method being characterised in that one or a plurality of additional gas jets are created on either side of the gaseous current carrying the fibres substantially in the same direction as that of the current, these additional jets being emitted along lateral walls bordering the perforated conveyor.
2. A method according to Claim 1, characterised in that the additional jets are emitted at velocities of the same order of magnitude or at a greater velocity than that of the gaseous current carrying the fibres at this level.
3. A method according to Claim 1 or Claim 2, characterised in that the gas mass introduced is at most equal to one fiftieth of the mass of the gaseous current carrying the fibres.
4. A method according to any one of the preceding Claims, characterised in that the additional jets are emitted in a direction parallel to the plane of the conveyor and making at most an angle of 20° with the plane of the lateral walls of the receiving chamber.
5. A method according to any one of the preceding Claims, characterised in that the jets are emitted in the form of flat gaseous layers substantially parallel with the lateral walls of the receiving chamber.
6. A method according to any one of the preceding Claims, in which the mass of additional gas introduced is regulated separately on either side as a function of the correction to be made to the distribution.
7. A method according to Claim 6, characterised in that the transverse distribution of fibres in the felt is controlled continuously, the measurements taken being analysed and compared with reference data in a calculating means which processes replies in the form of a command of the means regulating the emission of additional gases.
8. Installation for forming a felt of fibres comprising a fibre-forming assembly constituted by one or a plurality of centrifuging wheels onto which the material is conveyed from the outside, blower means creating a gaseous current along the periphery of the centrifuging wheels, a fibre receiving chamber extending in the direction of progress of the gaseous current carrying the fibres, the said chamber having in its base a perforated conveyor laterally edged by two walls, suction means situated under the conveyor, characterised in that additional blower means are disposed close to the lateral walls, the orifices ot these blower means being directed in such a way that the gases emitted pass along the lateral walls.
9. Installation according to Claim 8, in which the blower means are constituted on each side of the fibre receiving chamber by a plurality of blower nozzles spaced vertically one from another along the end of the lateral walls.
10. Installation according to Claim 8, characterised in that the blower means comprise on either side a single nozzle extending vertically along the lateral walls.
11. Installation according to one of Claims 8 to 10, characterised in that it comprises furthermore means of measuring the distribution of the fibres transversely of the felt formed, a calculator assembly for processing these measurements comparing the results with reference values and processing replies in the form of a command of means of regulating the emission of additional gases.
EP84400358A 1983-02-23 1984-02-22 Fibre distribution in a fleece Expired EP0119124B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8302897 1983-02-23
FR8302897A FR2541323A1 (en) 1983-02-23 1983-02-23 IMPROVING DISTRIBUTION IN A FELT OF FIBERS PRODUCED FROM CENTRIFUGATION WHEELS

Publications (2)

Publication Number Publication Date
EP0119124A1 EP0119124A1 (en) 1984-09-19
EP0119124B1 true EP0119124B1 (en) 1986-07-09

Family

ID=9286173

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84400358A Expired EP0119124B1 (en) 1983-02-23 1984-02-22 Fibre distribution in a fleece

Country Status (22)

Country Link
EP (1) EP0119124B1 (en)
JP (1) JPS59157365A (en)
KR (1) KR910006412B1 (en)
AT (1) ATE20677T1 (en)
AU (1) AU568532B2 (en)
BR (1) BR8400796A (en)
CA (1) CA1208913A (en)
DD (1) DD216492A5 (en)
DE (1) DE3460273D1 (en)
DK (1) DK155223C (en)
ES (1) ES529983A0 (en)
FI (1) FI76842C (en)
FR (1) FR2541323A1 (en)
GR (1) GR79525B (en)
IE (1) IE54964B1 (en)
IN (1) IN162862B (en)
IS (1) IS1462B6 (en)
NO (1) NO156870C (en)
PT (1) PT78139B (en)
TR (1) TR21695A (en)
YU (1) YU42895B (en)
ZA (1) ZA84931B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI83888C (en) * 1988-02-17 1991-09-10 Pargro Oy Ab Process and apparatus for producing a fiber product
EP1228010B1 (en) 1999-09-28 2008-04-09 Rockwool International A/S Compressed, packaged roll of MMVF batt and fabrication process of roll and MMVF web

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE741598C (en) * 1942-06-18 1943-11-13 Glaswatte Ges M B H Method and device for the production of a continuous fleece strip from glass fibers or similar fibers
BE727766A (en) * 1968-02-01 1969-07-31
US3582432A (en) * 1969-04-01 1971-06-01 Owens Corning Fiberglass Corp Fiber mat forming hood with movable side walls
FR2294967A1 (en) * 1974-12-18 1976-07-16 Monsanto Co FILAMENT DRIVING METHOD AND DEVICE
US4343639A (en) * 1980-04-25 1982-08-10 Bayer Aktiengesellschaft Process for production of fiber mats
FR2500492B1 (en) * 1981-02-24 1985-07-26 Saint Gobain Isover IMPROVEMENT IN METHODS AND DEVICES FOR FORMING MINERAL FIBERS USING CENTRIFUGATION WHEELS
FR2510909A1 (en) * 1981-08-06 1983-02-11 Saint Gobain Isover METHOD AND DEVICES FOR IMPROVING THE DISTRIBUTION ON A FUEL RECEIVING MEMBER VEHICLED BY A GASEOUS CURRENT

Also Published As

Publication number Publication date
BR8400796A (en) 1984-09-25
ES8500359A1 (en) 1984-11-01
NO156870C (en) 1989-02-21
IS1462B6 (en) 1991-03-26
TR21695A (en) 1985-03-05
FI840738A (en) 1984-08-24
JPH0351823B2 (en) 1991-08-08
DK155223C (en) 1989-08-07
ZA84931B (en) 1984-09-26
GR79525B (en) 1984-10-30
DD216492A5 (en) 1984-12-12
KR850002497A (en) 1985-05-13
ATE20677T1 (en) 1986-07-15
ES529983A0 (en) 1984-11-01
IE54964B1 (en) 1990-03-28
NO840647L (en) 1984-08-24
FI76842B (en) 1988-08-31
CA1208913A (en) 1986-08-05
FR2541323A1 (en) 1984-08-24
PT78139A (en) 1984-03-01
NO156870B (en) 1987-08-31
AU2454884A (en) 1984-08-30
DE3460273D1 (en) 1986-08-14
KR910006412B1 (en) 1991-08-21
DK75384A (en) 1984-08-24
YU33884A (en) 1986-10-31
EP0119124A1 (en) 1984-09-19
FR2541323B1 (en) 1985-03-29
IE840361L (en) 1984-08-23
IS2880A7 (en) 1984-08-24
DK75384D0 (en) 1984-02-17
FI76842C (en) 1988-12-12
YU42895B (en) 1988-12-31
DK155223B (en) 1989-03-06
JPS59157365A (en) 1984-09-06
IN162862B (en) 1988-07-16
PT78139B (en) 1986-03-21
AU568532B2 (en) 1988-01-07
FI840738A0 (en) 1984-02-22

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