EP2173935A2

EP2173935A2 - Device for an apparatus for forming fibre blankets

Info

Publication number: EP2173935A2
Application number: EP08826787A
Authority: EP
Inventors: Johan Heggelund; Renaud Roquigny; Oleg Boulanov
Original assignee: Saint Gobain Isover SA France; Glava AS
Current assignee: Saint Gobain Isover SA France; Glava AS
Priority date: 2007-07-26
Filing date: 2008-07-25
Publication date: 2010-04-14
Anticipated expiration: 2028-07-25
Also published as: FR2919313A1; JP5595911B2; PL2173935T3; AU2008281609A1; AU2008281609B2; FR2919313B1; JP2010534773A; CL2008002194A1; RU2466222C2; US20100218560A1; ES2449575T3; WO2009016324A2; AR067720A1; RU2010107054A; WO2009016324A9; US8276404B2; WO2009016324A3; EP2173935B1

Abstract

Device (6) for an apparatus for forming fibre blankets, the fibres being formed from a material that can be attenuated by internal centrifugation and by attenuation by means of a gas stream, the device comprising a guiding duct (60) into which the fibres are intended to be channelled, of longitudinal axis (X), which duct has a first part (61) intended to form the inlet of the duct at the point where the fibres are intended to be introduced into said duct, a second or central part (62) and a third part (63) intended to form the outlet of said duct, characterized in that it includes articulation means (7) that are suitable for acting mechanically on the third part of the duct (63) so as to vary its dimensions and/or the position of at least one of its parts relative to said longitudinal axis (X).

Description

DEVICE FOR A MATTRESS FORMATION FACILITY

FIBER

The invention relates to the formation of fiber mattresses such as those intended for thermal and acoustic insulation, and more particularly concerns a device for improving the distribution of fibers which are collected on a receiving member.

The formation of fibers, in particular of mineral fibers such as glass fibers, results from a fiber drawing process consisting of the drawing of the material, such as glass, by centrifugation and by the action of gaseous streams at high temperature. .

The fiberization process commonly used today is the so-called internal centrifugation process. It consists in introducing a net of the meltable material in a molten state in a centrifuge, also called fibering plate, rotating at high speed and pierced at its periphery by a very large number of orifices through which the material is projected into form. of filaments under the effect of centrifugal force. By means of an annular burner, these filaments are then subjected to the action of an annular gaseous stream of drawing at high temperature and speed along the wall of the centrifuge which reduces their diameter and transforms them into fibers.

On the other hand, the drawing gas stream is generally confined by means of an enveloping cold gas layer which adequately channels it in the form of a tubular flow. This gaseous layer is produced by a blowing ring surrounding the annular burner. It also helps to cool the fibers whose mechanical strength is thus likely improved by a thermal quenching effect.

It is also common to add an annular inductor below the centrifuge to help maintain the thermal balance of the plate. This inductor makes it possible to heat the bottom of the peripheral band of the plate which is less heated by the drawing gases because further away from the annular burner, and which is subjected to cooling by the ambient air.

The formed fibers are entrained by the draw gas stream to a receiving mat generally consisting of a gas permeable web on which the fibers become entangled in the form of a mat.

To fix the fibers together, a binder is usually sprayed onto the fibers as they travel to the receiving mat. The projection of the binder is for example carried out using a sizing ring which surrounds the gas stream and which comprises a plurality of spray orifices.

The binder is then cured for example by heat treatment beyond the receiving mat.

One of the difficulties encountered in the preparation of these mattresses is related to the distribution of the fibers in the entire mattress that is desired the most uniform. An irregularity of the distribution in the mattress may result in a local density lower than the desired density, which is generally corrected in the manufacture by increasing the average density of the mattress. However, it is always desirable to reduce the density of a product to make it lighter and obtain insulation performance, especially thermal, equally good. We are therefore continually looking for a production line to homogenize at best the distribution of the fibers in the mattress.

One known means for improving the distribution of fibers is the use of a so-called "bucket" device, such as that described in patent application FR 2 544 754, which is constituted by a guide duct disposed on the path of the gas stream below the centrifuge and above the binder spraying device. This duct makes it possible to channel the fibers; it is animated by an oscillation movement to alternately direct the flow of fibers from one edge to the other of the fiber receiving mat.

However, this oscillation movement with a substantially brutal return to each amplitude, on the one hand, does not appear optimum when the fibers are driven in the air stream, and on the other hand, increases the friction of the fibers. fibers against the walls of the device, which tends to degrade the mechanical properties. Another known means consists in blowing air towards the tubular gas flow, substantially perpendicularly to cross it.

Patent FR 1 244 530 thus describes two nozzles which are arranged beyond the binder spraying device and diametrically opposed to the gas flow, and whose air jets are actuated in turn to print the fiber web a movement back and forth when it lands on the reception mat.

US Pat. No. 4,266,960 shows two devices which each provide a jet of flat air arriving at high speed perpendicularly and in the tubular gas flow, the two devices being arranged on either side of the gas flow so that the orientation jets of air ensure a separation of the tubular flow into several divergent flows.

These various air blowing means thus force the air to be directed substantially perpendicular to the tubular web of fibers to divide the tubular flow and / or change its orientation.

The object of the invention is to provide a device for the manufacture of fiber mattresses in order to improve the distribution of the fibers in a mattress, in particular by preserving the required quality of the fibers at the output of the drawing, this device not presenting the disadvantages of the prior art, in particular the swinging device, and to obtain homogeneous mattresses, the desired density for a given thermal or insulating performance.

According to the invention, the device, more particularly intended for a fiber mat forming installation, the fibers being formed from a stretchable material by internal centrifugation and by drawing by means of a gaseous stream, comprises a conduit of guide in which the fibers are intended to be channeled, of longitudinal axis (X) and which has a first portion intended to form the inlet of the conduit at which the fibers are intended to be introduced into said conduit, a second part or central portion and a third portion intended to form the outlet of said duct, the device being characterized in that it comprises hinge means which are adapted to act mechanically on the third portion of the duct so as to vary its size and or the position of at least one of its parts with respect to said longitudinal axis (X). The dimension of the third portion of the duct which is likely to vary generally and preferably corresponds to its cross section (in a plane perpendicular to the longitudinal axis X). This section is usually circular, but can also be elliptical, or have any other shape.

The device thus makes it possible by modifying the outlet section of the guide duct to favor and adapt the expansion of the fiber web to ultimately manage the distribution of the fibers in the mattress. The size of the outlet section is particularly adapted according to the diameter of the centrifuge device, the height of drop of the fibers from the centrifuge device to the receiving belt, and the number of centrifugal devices located above the conveyor belt, so that, depending on the width of the carpet, the fibers are distributed over the entire width of the carpet and do not stick to the bat-flank of the installation bordering the carpet.

In addition, this device which is intended to remain essentially fixed in a fiberizing installation is thus easier to use and allows better accessibility to the other components of the fiberizing installation in comparison with a standard swing device which oscillates during fiber drawing. It has the following advantages in particular: there is no need to adjust a sway amplitude,

the cleaning of the sizing ring during fiber drawing is facilitated,

- The binder distribution is obtained more homogeneously on a veil falling in a direction substantially fixed and non-moving due to oscillations; the friction of the fibers against the walls is certainly reduced.

The third part of the conduit of the device according to the invention is generally mobile, at least partially, in particular so that its dimensions can vary. This third part may also be mobile, totally or partially, with respect to the longitudinal axis, for example in a plane substantially perpendicular to this axis.

The device of the invention which ensures a more uniform distribution of the fibers in a mattress allowing a decrease in the density of this mattress, the product is therefore lighter and cheaper to produce while maintaining the same insulation properties. Density reduction also makes it possible for the same flow rate of the stretched melt to increase the quantity of mattresses produced.

To provide the section modification of the outlet of the guide duct, the third portion of the duct may be in the form of a flexible skirt made of an extensible membrane. The modification of the dimensions of the skirt may for example result from inflation or any other mechanical stress. The skirt may for example take the form of a torus or more generally of any volume generated by the rotation of any shape around an axis located in its plane. The introduction of air into the torus makes it possible to inflate the structure, thus modifying the outlet section of the guide duct.

To provide the modification of the section of the outlet of the guide duct, the third portion of the duct is preferably constituted by a plurality of flanges arranged so as to constitute a solid wall, the hinge means being able to act concomitantly on the mobility of the flanges relative to the axis (X).

Each flange preferably has two opposite lateral edges, one of which overlaps the lateral edge of the adjacent flange, and the mobility of the flanges consists of a pivoting of the flanges towards or away from the X axis, the overlap of the flanges allowing the sliding of a flange against another to ensure their joint inclination. The movement operated by the flanges to increase or decrease the outlet section of the duct can be likened respectively to the opening or closing of the petals of a flower corolla. Alternatively, the flanges can be disjoint, that is to say do not overlap.

According to one characteristic, the flanges are inclined at most 10 °, and preferably at most 7 °, with respect to the axis (X) and in a direction divergent with respect to the axis (X).

The flanges may also be inclined at most 10 °, and preferably at most 7 °, relative to the axis (X) and convergently towards the axis (X). The degree of inclination and the convergence or divergence of the duct outlet relative to the X axis will be adapted to suitably adjust the expansion of the fiber web.

The hinge means acting mechanically on the third portion of the duct so as to vary its dimension, especially those acting concomitantly on the mobility of the flanges relative to the X axis can be very diverse. They will most often consist of mechanical systems capable of simultaneously applying pressure on each of the flanges. Each of these mechanical systems can be controlled mechanically and / or electrically and / or hydraulically.

These articulation means may consist of a ring of fixed diameter, whose main plane is perpendicular to the longitudinal axis X, said ring being further movable in translation, parallel to said longitudinal axis X, and surrounding the wall formed by the flanges by exerting a compressive stress on these. This ring movable in translation can advantageously be secured to the flanges by means of connecting means. In particular, the flanges may be provided with oblong windows provided longitudinally in which these connecting means can slide. The height adjustment of the mobile ring in translation makes it possible to adjust the degree of inclination of the flanges. The ring can also contribute to a modification of the position of the third part of the duct with respect to the longitudinal axis: by a movement of the ring in its plane, it is possible to print the flanges an overall movement , which can contribute to optimizing the distribution of fibers in the mattress.

The hinge means may also consist of a ring surrounding the wall formed by the flanges by exerting a stress on the latter, the diameter of the ring being variable. In this case, it is simpler to provide a ring whose main plane is fixed and perpendicular to the longitudinal axis X. The ring of variable diameter is preferably integral with the flanges. A contraction of the diameter of the ring is thus able to force an inclination of the flanges in the direction of the longitudinal axis X, thus an increase of the convergence of the outlet of the duct with respect to the same axis, whereas a widening of said diameter leads instead to a increasing the divergence of the duct outlet relative to this axis. Any device making it possible to obtain a ring of variable diameter can be used, such as for example devices of the diaphragm type, noose, or inflatable torus. In the latter case, a torus (or more generally a volume generated by the rotation of a shape about an axis located in its plane) consisting of a flexible membrane capable of being inflated, can by inflation see its internal diameter is reduce, thus creating a constraint on the flanges able to incline them in the direction of the longitudinal axis.

Preferably, the hinge means consist of a ring able to be rotatable and which is connected to the flanges to act simultaneously on them, the rotation of the ring being intended to generate a constraint which is exerted on a portion of flanges, the angle of rotation being related to the desired angle of inclination of the flanges relative to the axis (X).

Advantageously, the device comprises mechanical actuation means acting on the rotation of the mobile ring, these actuating means being manually controlled or controlled by electronically controlled means.

According to another characteristic, all the parts of the guide duct form a solid wall duct, so that no disturbance induced air can penetrate inside the device laterally to the haze.

Advantageously, the first portion of the guide duct, opposite the central portion, has a flared opening shape so as to facilitate the entry and guiding of the fibers in the duct.

In addition, the first part of the duct comprises its wall which has at its free end preferably a concavity profile facing the inside of the device. The curvature of the wall may have a fixed or variable radius of curvature, of a geometric shape, respectively, circular or elliptical, parabolic. This profile ensures that the ambient air enters the duct better by sliding along the inside of the duct wall, providing a guiding channel for the fibers and providing a protective barrier against the fibers which thus avoids stick to the wall. According to one feature, the flanges of the third portion have on the inner side of the duct a concave shape to help form the cylindrical shape of the inside of the duct.

The invention also relates to a fiber mat forming installation comprising a device for centrifugation of a stretchable material, in particular glass, which is provided with a fibering plate delivering filaments of said material, and a drawing device gas which provides a gaseous stream at high temperature and which ensures the transformation of the filaments into fibers in the form of a substantially tubular web, the installation being characterized in that it comprises a device for guiding duct for improving the distribution of the fibers of the web as described above according to the invention.

The installation generally comprises an inductor which is arranged under the centrifugation device, the guide duct device being placed near and under the inductor.

During operation of the installation, the guide duct preferably has its longitudinal axis (X) fixed relative to the axis (A) of fall of the fiber web. But the guide duct may rather have its longitudinal axis (X) parallel or inclined relative to the axis (A) of fall of the fiber web.

Advantageously, the articulation means of the guide duct are operable during operation of the fiberizing installation so as to correct the dynamic distribution of the fibers.

Advantageously, the guide duct, which comprises flanges extending substantially parallel to the axis of the duct and arranged in a circular manner and tilting in convergence or divergence with respect to the central axis of the duct and which have their lateral edges such that the edge of a flange overlaps from the outside the edge of an adjacent flange, is disposed in the installation so that the direction of overlap is directed in the opposite direction of rotation of the centrifuge, and therefore in the opposite direction of rotation of the web inside the conduit. In this way, the fibers can not stick to the level of the gap of overlap of the flanges, because the rotating veil thus runs along the inside of the flanges without risk of getting in precisely at the interstice.

Preferably, particularly when the guide duct device is disposed at least immediately below the inductor, it is made of a material resistant to heat and does not capture the magnetic field generated by the inductor.

The installation may comprise a binder supply device which is arranged downstream of the device for improving the distribution of the fibers.

In addition, a device for blowing air towards the web, such as blowers, can be provided by being positioned under the binder supply device; it allows in certain conditions related in particular to the width of the receiving mat, to further optimize the distribution of fibers in the mattress.

The terms upstream and downstream in the following description must be understood as the higher and respectively lower parts of an element facing a part of the installation which, set up for its operation receives the flow of the fiber material from top to bottom. And the terms horizontal and vertical for elements of the guide duct are understood with respect to the arrangement of the guide duct which extends substantially vertically.

Finally, the invention relates to a method of manufacturing a fiber mat using the device of the invention to improve the distribution of fibers in the mattress.

Other advantages and features of the invention will now be described in more detail with reference to the accompanying drawings, in which: FIG. 1 represents a schematic partial sectional view of a fiber mattress forming installation comprising a device for improvement of fiber distribution according to the invention;

FIG. 2 illustrates a side view of an embodiment of the device of the invention;

FIG. 3 is a diagrammatic view in section and from below of the device of the invention; FIG. 4 illustrates a schematic view in vertical and partial section of the device of the invention inserted in a fiberizing installation;

FIG. 5 is a diagrammatic sectional view of an embodiment of the device according to the invention;

Figure 6 illustrates curves on the change in basis weight versus nominal basis weight of a fiber mat as a function of the width of the receiving mat.

The representations illustrated in the figures are schematic without being strictly scaled for ease of reading.

FIG. 1 represents a partial view, in cross section and in a vertical plane, of a fiber felt forming installation according to the invention.

The plant 1 comprises in known manner from upstream to downstream, or from top to bottom in the direction of flow of the melt stretch material, an internal centrifuge device 10 which delivers filaments of a stretchable material. , a drawing device 20 delivering a gaseous stream which transforms the filaments into fibers, an annular inductor located under the centrifuge device 10, a binder supply device 40, a fiber receiving mat 50 on which accumulate the fibers by suction to form the mattress.

According to the invention, the installation further comprises a device for improving the distribution of fibers 6 on the conveyor belt 50. This device is located between the inductor 30 and the binder supply device 40.

The centrifugation device 10 comprises a centrifuge, also called a fiberizing plate, rotating at high speed and pierced at its peripheral wall by a very large number of orifices through which the melt is projected in the form of filaments under the effect centrifugal force.

The drawing device 20 comprises an annular burner which delivers a gaseous stream at high temperature and speed along the wall 12 of the centrifuge. This burner serves to maintain the high temperature of the wall of the centrifuge and contributes to the thinning of the filaments to transform them into fibers which fall in the form of a substantially tubular web 2 of axis A. The stretching gas stream is generally channeled by means of an enveloping cold gas layer. This gaseous layer is produced by a blowing ring 21 surrounding the annular burner. It also makes it possible to aid the cooling of fibers whose mechanical strength is thus improved by a thermal quenching effect.

Annular inductor 30 heats the bottom of the centrifuge device to help maintain the thermal balance of the plate.

The device for improving the distribution of the fibers 6 comprises a guide duct 60 extending along a longitudinal axis X, which makes it possible to channel the tubular web passing through the duct, and articulation means 7 able to modify the section of the duct. output of the guide duct 60 to promote and regulate the expansion of the fiber web at the outlet of the duct to ultimately manage the distribution of the fibers. The device will be described in more detail later. The improvement device 6 is fixed relative to the other devices of the fiberizing installation.

The binder supply device 40 consists of a sizing ring through which the tubular web of fibers flows. The crown comprises a multiplicity of nozzles basting the veil of fibers.

The device of the invention 6 may optionally be associated with a known compressed air blowing system 41, in dashed lines in FIG. 1, such as blow guns, which will be positioned below the sizing ring 40.

The fiber web is then deposited on the conveyor belt 50.

Figure 2 shows in more detail the device of the invention.

The solid-walled guide duct 60 has a first upstream portion 61 intended to constitute the entry of the duct for the fiber web, a second central portion 62 and a third downstream portion 63 intended to constitute the outlet of the duct for the web of the web. fibers.

The upstream portion 61 has a flared shape in the direction of the drawing device to facilitate entry and channeling of the fiber web in the conduit. More particularly, the wall 61a advantageously has a curved profile towards the inside of the device in the direction of the axis X, whose concavity may have a fixed or variable radius of curvature such as that of a circle or an ellipse (Figure 4).

The central portion 62 is of cylindrical shape with a longitudinal axis X, it extends in the continuity of the first portion 61 and is preferably a single piece with said first portion.

The downstream portion 63 is attached to the central portion 62 to provide continuity of the conduit. According to the invention, the downstream portion 63 has a circular section capable of varying. This section may be varied during the operation of the fiberizing installation.

Thus, the duct 60 has a generally tubular shape with a neck flared at one of the free ends and an opposite free end which is either flared or narrowed, respectively according to the diameter imposed on the downstream part 63 with respect to the diameter of the central part 62.

The variation of the diameter of this downstream part 63 is obtained by the particular configuration of the constituent elements and by articulation means 7 adapted to act on the mobility of the constituent elements.

According to an exemplary embodiment which is in no way limiting, the lower part 63 consists of a plurality of flanges 64 which extend parallel to the axis X and are arranged in a circular manner, and preferably with a concavity turned inwardly of the conduit to easily provide a cylindrical shape within the conduit.

The flanges 64 have an upper portion 64a, a lower portion 64b and opposite side edges 64c and 64d. The portion 64a of the flanges partially covers the central portion 62 of the duct to ensure closure continuity over the entire periphery of the duct to prevent any induced air penetration. The lower portion 64b corresponds to the outlet of the conduit 60.

The flanges are laterally superimposed on each other so that the lateral edge 64c of a flange overlaps the outside edge of the duct with the lateral edge 64d of the adjacent flange, as can be seen in FIG. 3, which shows a sectional view and a bottom view of the flange. leads to the level of the lower part 63.

Advantageously, the device is disposed in the fiberizing installation so that the direction of overlap is in the opposite direction of rotation of the centrifugation device, and therefore in the opposite direction of rotation of the web inside the conduit (symbolized by the arrow inside the conduit). In this way, the fibers of the rotating web which thus skirt the inside of the flanges are not likely to be introduced at the gap 65 of overlapping flanges.

The flanges 64 are associated with the articulation means 7 which simultaneously act by stress on the upper portion 64a of the flanges to generate their inclination.

As a function of the force exerted on the flanges, the inclination with respect to the axis X is variable, according to an angle α which varies from -10 ° with a divergent direction relative to the axis X, to + 10 ° with a convergent direction towards the X axis, the reference 0 ° corresponding to the parallelism of the flanges with the axis X and the central part 62.

The articulation means 7 are adjusted so that when no force is exerted on the upper portion 64a, the inclination of the flanges is divergent with respect to the axis X and maximum angle.

According to a non-limiting embodiment, the articulation means 7, as illustrated in FIG. 2, comprise holding tabs 70, a ring 71 able to be rotatable which is connected to the holding tabs via mechanical links 72, a fixed ring 73 supporting the movable ring 71, and an actuating system 74 adapted to slide in rotation the movable ring 71 relative to the fixed ring.

The holding tabs 70 are fixed relative to the flanges 64 and are integral with them being for example screwed or welded.

The tabs 70 serve to hold the flanges in position, the tabs being supported via the mechanical links 72 by the movable ring 71 which is itself supported by the fixed ring 73.

Each leg is made movable by its inclination relative to the central portion 62 of the duct, to precisely tilt each flange relative to the central portion 62. Each lug 70 thus comprises a seat 70a welded to the central portion 62 and a pivot 70b Y axis perpendicular to the axis X and around which the tab is intended to articulate. The fixed ring 73 which supports the movable ring allows the rotational sliding of the movable ring 71 by a fastening screw adapted to sliding.

In addition, the fixed ring 73 serves to maintain in place around the guide duct 60 the movable ring 71 because it is secured by surrounding, the upstream portion 61 of the duct.

The use of a ring to connect in one piece all the flanges can act concomitantly on the flanges.

The mechanical connection 72 of each tab 70 to the movable ring 71 is formed by a rod extending in a vertical plane and inclined in this plane (Figure 2). One of its ends is connected to the ring 71 while its opposite end is connected to the pivot 70b of the tab.

The connecting rod responds to the difference in height between the retaining tab disposed at the portion 64a of the duct and the ring arranged at the portion 61. It is intended to move in a vertical plane and allows to transform, the horizontal movement of rotation sliding of the ring, in a pivoting movement of the holding tabs around each axis Y.

Indeed, the distance between the two ends of the connecting rod remaining constant and the holding lug being attached to both a flange and the central portion 62, the rotation of the ring 71 in one direction or the other leads necessarily to modify the inclination of the rod which will be either more vertical, or will incline more towards the horizontal one. The more the inclination is vertical, the greater the stress exerted on the retaining tab will be important, the pivoting of the tab will then be in the counterclockwise direction leading to the inclination of the flange in the direction of the X axis. On the contrary, more the inclination of the connecting rod will approach the horizontal, the more the stress exerted on the tab will relax causing the pivoting of the tab in the clockwise direction and leading to the inclination of the flange opposite the X axis.

Finally, the actuating system 74 acting on the mobility of the ring 71 has two fixing points which are respectively positioned on the fixed ring 73 and on the movable ring 71, a nut 73a and respectively a nut 71a in which is engaged a threaded rod 74a. Clamping or loosening of the rod causes the sliding nut 73a of the movable ring to slide in rotation relative to the other nut 71a which remains fixed, causing the mobile ring to slide in one direction or the other in rotation.

Actuation of the rod can be done manually by an operator or can be provided by electronically controlled means in response to an order communicated by a controller.

The articulation means 7, as illustrated in FIG. 5 according to another non-limiting embodiment, consist of a ring of fixed diameter 75, shown in section, whose main plane is perpendicular to the axis. longitudinal X. The ring 75 is movable in translation, parallel to said longitudinal axis X (according to the arrow), thanks to a shaft 76 integral with the ring 75. The ring 75 surrounds the wall formed by the flanges by exerting a constraint compression on these. The height adjustment of the ring 75 makes it possible to adjust the degree of inclination of the flanges. Figure 5 shows schematically two positions of the ring 75: a first "high" position, shown in solid lines, and a second "low" position shown in dashed lines. In both cases, the flanges 64 are represented, also in solid lines in the case where the ring 75 is in the high position, and in dashed lines when the ring 75 is in the low position. Figure 5 clearly shows that the lowering of the ring 75 makes it possible to incline the flange towards the axis X, and thus to reduce the divergence of the flange with respect to this axis. It is also possible to move the ring 75 in its plane, so in a plane perpendicular to the X axis to print the flanges, and therefore the entire third part of the duct, a movement.

The device of the invention has its axis X generally parallel to the axis of delivery of the fiber web. However, since the device of the invention is not glued to the inductor, turbulence of the ambient air can affect the orientation of the web entering the device. Also it may be relevant to incline as in the prior art a swinging device, the device of the invention with respect to the axis A, as schematically illustrated in Figure 4, to correct the orientation of the fiber veil due to the right-left suction inhomogeneity of the carpet 50. Figure 6 illustrates three curves as to the variation (in%) of the mass per unit area of a fiber mat compared to a nominal reference density (here of 848 g / m ² ), depending on the width of the carpet of receiving (from 0 cm for the left edge of the carpet to 240 cm for the right edge of the carpet), the curves respectively corresponding to a reference configuration of a guide duct and two configuration variants of the device of the invention .

The pilot plant used to test the device of the invention delivers a fiber mat of 2400 mm wide. A gauge of grammage scans the width of the mattress over a given length of said mattress, to deduce an average weight. Several average weight estimates are made and are converted to weight values (weight per unit area). We deduce the illustrated curves.

The average of these average weights and the standard deviation of these measurements were also calculated so as to deduce the coefficient of variation of surface mass (CV) by the ratio between the standard deviation and the average of the weights.

Measurements on the mattress were made at different angles of inclination of the flanges, the device being fixed, of general direction X parallel to the delivery axis of the web A:

For the reference curve C1, the angle of inclination of the flanges is 0 ° with respect to the axis X, that is to say that the diameter of the outlet 63 of the guide duct corresponds to the diameter of the flange. central portion 62, and the blowing system 41 was used. The coefficient of variation of the calculated surface density CV is equal to 25%.

For the curve C2, the angle of inclination of the flanges is 5 ° divergent with respect to the X axis and the blowing system 41 was used under the same conditions as for the curve C1. The coefficient of variation of the calculated surface density CV is equal to 23%.

For the curve C3, the angle of inclination of the flanges is divergent by 5 ° with respect to the axis X just as for the curve C2, on the other hand, the blowing system 41 has been modified with respect to the conditions of the curve C1 or C2, in particular by lowering the air pressure breath. The coefficient of variation of the calculated surface density CV is equal to 7%.

It can be seen that for the curve C1, the fiber web dispersed by the blowing system 41 at the outlet of the guide duct is not homogeneously distributed over the width of the carpet. The breakdown is as follows:

- At both ends of the carpet, the fibers are fewer (hollow with a variation up to 80%);

- always on the left and right edges of the carpet but getting closer to the center, there is an excess of fibers (bumps characteristic of the curve of up to 140% or even 160%);

- while the center of the carpet has significantly less fiber (hollow around 80%).

For the curve C2, the fiber web expands at the flared exit of the guide duct (divergence of 5 ° according to a variant of the invention). It can be seen that it was possible to compensate for the lack of fibers at the ends of the carpet, the coefficient being well above 100% with respect to the mentioned depressions of the curve C1, while nevertheless losing fibers in the middle of the carpet (coefficient one slightly lower than for C1). This configuration of the device of the invention nevertheless makes it possible to smooth the distribution of the fibers relative to the reference device relating to the curve C1. In addition, the coefficient of variation of surface mass increases in points from 25 to 23%.

The decrease of the air pressure blown by the blowing system 41 according to the last configuration relating to the curve C3 makes it possible to further homogenize the distribution with respect to the curve C2, the curve C3 being substantially stable around 100%. In addition, the coefficient of variation of surface mass is even reduced to 7%.

The device of the invention thus leads to a better distribution of the fibers. In addition, associated with a blowing system of the prior art, such as 41, it generates a lower consumption of compressed air.

Claims

Apparatus (6) for a fiber mat formation apparatus, the fibers being formed from stretchable material by internal centrifugation and drawing by means of a gas stream, the apparatus comprising a guide duct (60) ) in which the fibers are intended to be channelized, of longitudinal axis (X) and which has a first portion (61) intended to form the inlet of the duct at which the fibers are intended to be introduced into said duct, a second portion or central portion (62) and a third portion (63) intended to form the outlet of said duct, characterized in that it comprises articulation means (7) which are adapted to act mechanically on the third part of the conduit (63) so as to vary its dimension and / or the position of at least one of its parts with respect to said longitudinal axis (X).

2. Device according to claim 1, characterized in that the third portion (63) consists of a plurality of flanges (64) arranged to form the wall of said third portion, the hinge means (7) being able to act concomitantly on the mobility of the flanges relative to the axis (X).

3. Device according to claim 2, characterized in that each flange (64) has two opposite side edges (64c, 64d), one of which overlaps the lateral edge of the adjacent flange and in that the mobility of the flanges consists of a pivoting flanges towards or away from the X axis.

4. Device according to claim 3, characterized in that the flanges (64) are inclined at most 10 °, and preferably at most 7 °, relative to the axis (X) and in a divergent direction relative to the axis (X).

5. Device according to claim 3, characterized in that the flanges (64) are inclined at most 10 °, and preferably at most 7 °, relative to the axis (X) and convergently to the axis (X).

6. Device according to any one of claims 2 to 5, characterized in that the hinge means (7) consist of a ring (75) of fixed diameter, the main plane is perpendicular to the axis longitudinal X, said ring being further movable in translation parallel to said longitudinal axis X, and surrounding the wall formed by the flanges by exerting a compressive stress on the latter.

7. Device according to any one of claims 2 to 5, characterized in that the hinge means (7) consist of a ring surrounding the wall formed by the flanges by exerting a stress on the latter, the diameter of the ring being variable.

8. Device according to any one of claims 2 to 5, characterized in that the hinge means (7) consist of a ring (71) which is adapted to be rotatable and which is connected to the flanges (64) to act simultaneously on them, the rotation of the ring being intended to generate a stress which is exerted on a portion (64a) of the flanges (64), the angle of rotation being related to the desired angle of inclination flanges relative to the axis (X).

9. Device according to the preceding claim, characterized in that it comprises mechanical actuating means (74) acting on the rotation of the movable ring (71), these actuating means being manually controlled or controlled by means electronically controlled.

10. Device according to any one of the preceding claims, characterized in that all the parts (61, 62, 63) of the guide duct form a solid wall duct.

11. Device according to any one of the preceding claims, characterized in that the first portion (61) of the duct comprises its wall (61a) which has at its free end a curved profile concavity facing the inside of the device.

12. Device according to any one of the preceding claims, characterized in that the first portion (61) of the duct, opposite the central portion (62), has a flared opening shape.

13. Device according to any one of claims 2 to 12, characterized in that the flanges (64) have on the inner side of the duct a concave shape to form the cylindrical shape of the inside of the duct.

Fiber mattress forming apparatus comprising a centrifugation device (10) of a stretchable material, in particular glass, which is provided with a fibering plate (11) delivering filaments of said material, and a device for stretching gas (20) which provides a high temperature gas stream and which converts the filaments into fibers in the form of a tubular web (2), characterized in that it comprises a device (6) with a duct guidance according to any one of claims 1 to 13.

15. Installation according to the preceding claim, characterized in that an inductor (30) is arranged under the centrifuge device (10), the guide duct device (6) being placed immediately below the inductor (30), and made of a material resistant to heat and not capturing the magnetic field generated by the inductor.

16. Installation according to any one of claims 14 or 15, characterized in that during operation of the installation, the guide duct (60) has its longitudinal axis (X) fixed relative to the axis ( A) Falling of the veil of fibers.

17. Installation according to the preceding claim, characterized in that the guide duct (60) has its longitudinal axis (X) parallel or inclined relative to the axis (A) of fall of the fiber web.

18. Installation according to any one of claims 14 to 17, characterized in that the hinge means (7) of the guide duct are operable during operation of the installation.

19. Installation according to any one of claims 14 to 18, characterized in that the guide duct (60) comprises flanges (64) extending substantially parallel to the central axis (X) of the duct and arranged so circular, the flanges being inclinable in convergence or divergence with respect to the central axis (X) of the duct and having their lateral edges such that the edge of a flange overlaps the outside of the edge of an adjacent flange, and in that the duct is arranged in the installation so that the direction of overlap of the flanges is directed in the opposite direction of rotation of the centrifugation device.

20. A method of manufacturing a fiber mat using the device according to any one of claims 1 to 13 to improve the distribution of fibers in the mattress.