EP0406107A1 - Process and apparatus for collecting mineral fibres - Google Patents

Abstract

The invention relates to the reception of fibers under fiberizing machines (1,2,3) with a view to obtaining a mineral wool mattress. It proposes to assign to each fiberizing machine its own collection zone (Z1, Z2, Z3), the surfaces of the collection zones being increasing in the direction of the increase in grammages. The invention also provides a device characterized by the presence of two receiving drums for three fiberizing machines.

Description

The invention relates to techniques for receiving mineral fibers known as insulation, in particular glass fibers, with a view to the separation under the fiberizing machines, of fibers and ambient gases - in particular gases induced or having served for the drawing of these fibers - in order to make a mineral wool mattress.

An important step in the manufacture of products based on mineral fibers such as glass fibers is that of their collection under the fiberizing machines. The purpose of this operation is in particular to separate the fibers and the large quantities of gas generated by fiberizing by the burners and especially by air induction. This separation takes place in a well-known manner by suction through a gas-permeable and fiber-impermeable receiving device.

A common type of receiving device called belt receiving is described for example in US-A-3,220,812 where it is proposed to receive fibers from a series of fiberizing machines on a single conveyor of the belt type without thin, gas permeable and under which is placed a vacuum chamber or better a plurality of independent vacuum chambers. In this type of reception, the fiber-drawing machines can be brought together to the limits of their respective dimensions, which allows relatively short lines; this point is not negligible if we know that some production lines can reach the number of 9 or more fiberizing machines, each fiberizing machine being of a diameter of the order of 600 mm for example. In addition, the only lower limit to the grammage (or surface mass) of the felt produced is that dictated by the problems of mechanical strength, which therefore allows the manufacture of the lightest products likely to be obtained.

However, obtaining heavy products poses many problems - in the rest of this document, heavy products are understood to mean products whose grammage is for example greater than 2.5 kg / m² in the case of glass wool products. whose micronaire is 3 per 5 g, with the exception of dense products obtained by molding and pressing which are not directly within the scope of the present invention. This difficulty in obtaining is easily explained by the fact that the heavier the mattress that it is sought to produce, the greater the quantity of fibers which are deposited on the same surface of the endless belt and therefore the greater resistance to gas passage. To compensate for this lower permeability, a greater depression must be exerted, which results in crushing of the felt by the pressure of the gases, especially sensitive crushing in the lower part of the felt which corresponds to the fibers harvested in the first place. As a result, the mechanical performance of the product, especially in terms of thickness recovery after compression, is less good. The resulting deterioration in the quality of the product is very noticeable as soon as the vacuum must be raised beyond 8000 to 9000 Pa, while in certain installations a vacuum of more than 10 000 Pa is already necessary for mattresses whose grammage is 2500 g / m².

To overcome this drawback, it is certainly possible to only partially aspirate the gases in order to limit the vacuum to a value which does not damage the felt, but there is then a phenomenon of discharge of the fibers in the direction of the fiberizing machines. In addition to hampering good stretching, this gas backflow increases the temperature in the fiber hood and therefore risk of pre-gelling of the binder, that is to say of a polymerization of the binder while the fibers are still in a unitary state, which removes almost all activity. In addition, this backflow can cause the formation of wicks, that is to say dense sets of agglomerated fibers, which affect the homogeneity of the product, its appearance and lower its thermal resistance.

One can also seek to reduce the speed of passage of the gases through the felts by separating the fiberizing machines from each other. However, the real gain is very small because the increase in the dimensions of the hood causes an increase in the air induction and therefore in the quantity of air to be sucked.

In a known variant of patent application EP-A-102 385, it has been proposed to separate the reception into two parts, each receiving the fibers produced by a fiberizing machine out of two. The reception then includes two conveyors oriented towards each other, so as to bring together the two half-felts formed. This type of reception has the advantage of providing products with a beautiful external appearance due to the presence on both sides of superglued crusts which improve the mechanical strength of the product. However, the size of the reception is greater than in a traditional reception and above all it can occur for heavy weights a beginning of polymerization of the binder before the meeting of the half-felts which initiates delamination of the product.

This notion of a subdivision of receptions was further developed in the publication US-A-4 120 676 which proposes to associate with each fiberizing machine a reception unit, the production line thus being conceived as a juxtaposition of modules base each producing a relatively thin felt, the various thin felts being subsequently stacked so as to form only a very thick felt.

This modular design allows fiberizing conditions to be kept constant whatever the product manufactured. However, it assumes that the lightest products are obtained with a line used very well below its theoretical capacity which is hardly interesting from an economic point of view.

Another example of modularization of mineral wool production lines is given by so-called drum receptions associated with a lapper. In this case exemplified by publication US-A-2785728, the reception is carried out on rotating members of the drum type. A primitive of low grammage is prepared by means of a receiving device facing one or two fiberizing machines, consisting of a pair of drums rotating in reverse rotation, the perforated surface of which allows the suction of gases by suitable devices placed in the drums. The primitive is formed between the drums and falls in a vertical plane before being taken up by the lapper, that is to say a pendulum device which deposits it in intertwined layers on a conveyor where the felt of the desired high grammage is obtained. .

These modular designs of receptions allow in theory to target a much wider range of products insofar as one systematically begins with the production of a felt of low grammage.

However, this supposes a greater initial investment with the multiplication of additional equipment (suction and washing devices in particular). Furthermore, the means of partitioning the receipts lead to a large spacing of the fiberizing machines and we come to exceptionally long production lines as soon as the number of fiberizing machines is multiplied.

In addition, the risks of delamination and inhomogeneity of the product prohibit the production of felts of lower grammages. Thus a lapper imposes a primitive of at least 100 g / m² below which its mechanical resistance would be insufficient in particular to support the movements of the pendulum, and a sufficient number of superimposed layers - to have an optimization of the distribution with in every point of the felt the same number of layers.

Furthermore, operating systematically with the same fiber mass flow rate certainly amounts to placing oneself in conditions favoring the reproducibility of the fiberizing parameters and, by the same token, their optimization, but above all it is depriving ourselves of the extraordinary capacity of the fiberizing machines to operate according to flow rates of fiber material ranging for example from 1 to 10.

Finally, with equal fiber qualities, a product is sold at a lower price when its grammage decreases. It therefore seems unwise to place yourself precisely in the case where the line produces the lowest tonnages.

The object of the invention is a new conception of the reception of units for the production of felts in mineral wool, in particular in glass wool, tending to widen the range of products capable of being produced by the same production line; this widening of the range extending to both low and heavy weights so as to increase the versatility of the production line, while preserving or even improving the quality of the products obtained. The range of products produced goes, for example, from 300 g to 4000 g / m² or more, possibly by combining a lapper.

The invention provides a reception method for the separation of fibers and gases produced by a plurality of fiberizing machines with a view to obtaining a mineral wool mattress, method according to which the fibers are collected by suction of the gases, each fiberizing machine i having its own collection zone Zi, the fibers collected in the various collection zones Zi being removed from the collection zone by one or more zones Zi, this reception process being characterized by the fact that the surfaces collection zones Zi are increasing in the direction of increasing the grammages on said conveyor belts.

In other words, the closer a fiberizing machine i is to the place of final formation, the larger the collection zone Zi which is assigned to it, which makes it possible to compensate for the greater resistance to the passage of gases due to the removal on the same conveyor belts fibers from the more distant fiberizing machines.

Advantageously, one operates at a constant delivery rate.

By discharge rate is meant the percentage of gas not sucked in at the reception. Preferably, this rate is zero, and this in accordance with claim 1 even for fiberizing machines downstream of the line. The collection surfaces are preferably delimited on one side by the conveyor belts themselves, which therefore form receiving belts. We compensate for the increase in resistance to gas passage due to the removal of fibers from upstream fiberizing machines (always considering the line oriented in the direction of travel of the primitive). It should be noted that the receptions according to the invention are receptions common to several fiberizing machines and preferably to 3 or more fiberizing machines. The number of receptions per production line therefore generally does not exceed two, which avoids the drawbacks of excessive modularization.

On the other hand, the increase in the collection surface in the areas of heavy weights makes it possible to maintain in them relatively low levels of depression, for example advantageously less than 4000 Pa, that is to say at a good level. lower than the level for which the first damage is observed for high quality fibers such as glass fibers whose micronaire is for example 3 per 5 g.

Advantageously, one chooses to operate with the same level of vacuum for all the collection surfaces. In other words, we compensate completely from one collection zone to another, the slightest permeability of the felt due to the thickness of felt already deposited from other fiberizing machines - and this without harming the aspiration, because as indicated in the preamble sucking only part of the gases would lead to a backflow of the fibers, especially with the formation of wicks and therefore obtaining a product of poorer quality.

The present invention relates more specifically to cases where the fall heights of the fibers differ according to their original fiberizing machines, that is to say all case where the conveyor belts have a trajectory which is not horizontal but is generally convex. According to the invention, the surfaces of the collection zones Zi increase with the average distance that the fibers must travel to reach these collection zones Zi.

Advantageously, nothing is therefore changed in the position of the fiberizing machines - and therefore in the dimensions of the toroids (fibers and air) coming from these fiberizing machines, but the angle of inclination is changed to normal at the collection surface with respect to the axis of rotation of the toroids. The greater this angle of inclination, the larger the surface of the collector strip intercepted by the torus, which thus makes it possible to implement the invention without substantially modifying the distance between centers of the fiberizing machines.

Preferably, this variation of the angle of inclination is carried out continuously so as to avoid sharp angles which could adversely affect the final quality of the felt. The receiving strip on which the fibers from the different fiberizing machines are deposited then follows a trajectory which at least in its terminal portion is that which is convex, for example elliptical, curved.

Optionally, it is also possible to combine the use of convex receiving surfaces with an increase in the distance between two fiber-drawing machines located in the areas of higher grammages and / or with a progressive inclination of the axes of rotation of the fiber-drawing machines, these two methods also allowing the increase of the surfaces of the collection zones.

Preferably the fiberizing machines are divided into groups of for example 3 or 4 forming as many reception modules as groups: each module thus corresponds to a primitive and all the primitives formed are then collected before being driven in the form of '' a single felt in the binder polymerization oven. Generally at most two reception modules are necessary even for large tonnage production lines. There is thus a modularization of the reception, but a modularization which is intended to be limited in much smaller proportions than according to the prior art.

Depending on the case, the receiving modules can be arranged in series one after the other with a single glass feed channel for all fiberizing machines or in parallel with in this case as many molten glass feed channels as reception modules. Subsequently, the primitives are brought together by superposition in parallel layers or in intersecting layers, the choice between these two superposition modes being carried out in particular according to the densities desired for the final products.

It may also be advantageous to have, for each reception module, not one but two converging receiving bands facing each other and symmetrical to one another, the fibers deposited on one or the other band being gathered in a single felt at the common end of the receiving strips. In this case, the place of final formation of the felt is located at the point of convergence of the two receiving bands.

As the power required to drive the receiving bands is a function of the mass of fibers deposited on each of them, it is preferable to distribute the number of fiberizing machines in equal parts for each receiving band, which simplifies synchronization. speeds of the two receiving bands, synchronization necessary to prevent the two primitives formed from sliding over each other. If the fiberizing machines are in odd number, the last fiberizing machine preferably has a collecting surface shared between two receiving bands, the symmetry of the torus coming from a fiberizing machine allowing a division into two equal parts if one chooses to mount the receiver bands in such a way that their plane of symmetry contains the axis of symmetry of the torus of the central machine.

The curve drawn by the trajectory of a receiving strip is preferably a circle, the circular trajectories are certainly not the optimal trajectories calculated on the assumption for example of an equal depression in all the collection zones, but are of a practical point of view much simpler to put in artwork. In this case, the receiving bands are formed by the peripheral surface of one or two drums.

A more particularly preferred example is that of a receiving module with double drums per group of 3 fiberizing machines with the formation of a primitive between the two drums. When the production line comprises nx3 fiberizing machines, there are then n reception modules which form n primitives which are then gathered in a single mat before the polymerization of the resin intended to bind the fibers is caused.

The collection of primitives from the different modules can then be obtained as indicated above by superimposing them in parallel layers. The assembly, for example on a horizontal conveyor, of the primitives produced in a vertical plane between the drums can be done almost immediately under the drums so that the "life" time of these primitives is very short and that one does not notice not on the finished products of delamination phenomenon. The assembly can also be obtained by means of lappers.

The reception scheme thus defined - 3 fiberizing machines for two drums - is in fact very different from those known in the art - where there is either a collection surface distributed over two receiving bands (1 machine - 2 drums), or a conveyor belt serving as a collection surface specific to each machine (2 machines - 2 drums), and never conveyor belts common to several fiberizing machines. In addition to the immediate benefit of reducing the number of reception modules for the same production line, the preferred solution according to the invention has numerous advantages.

As according to the invention each reception is normally supplied by 3 fiberizing machines, the minimum grammage which can be obtained with for example a line of 6 fiberizing machines is only 200 g / m², it being understood that each reception must necessarily produce a primitive of at least 100 g / m² for a question of mechanical resistance. In comparison, a type of 2 drums reception by fiberizing machine - or 2 drums for 2 fiberizing machines - is only capable of producing mineral wool mattresses whose grammage is respectively at least 600 or 300 g / m². In fact, this lower limit of 200 g / m² is lower than the lightness limit of the products sold.

In addition, the drums constitute very large collecting surfaces capable of receiving high flow rates which correspond perfectly to the possibilities of fiberizing machines. The authors of the present invention have thus found that it is perfectly possible to directly produce a primitive of high grammage, without systematic use of the layers, the known disadvantage of which is a relatively low speed which limits the total speed of the line. production.

Another particularly advantageous point of the invention is that the greater efficiency of the suction leads to greater cooling of the felt; however, the colder the felt, the less the risk that the binder will polymerize before passing through the polymerization oven, which leads to final products with much better mechanical strength, a greater proportion of the resin actually used to bind the fibers. while too hasty polymerization is carried out practically in pure loss, the thickness of the felt not yet being controlled at this stage of the process. This lower temperature also leads to less evaporation of the size, a greater amount of which is found in the finished product, which reduces the costs of cleaning up the fumes.

For the implementation of this preferred form of the invention, the device associated with each group of 3 fiberizing machines includes a hood isolating each reception in which are placed a pair of drums perforated over their entire peripheral surface and provided with devices centering and rotation drive and fixed interior suction boxes when the drums are rotating. The suction surface corresponds to the peripheral surface of the drum placed inside the hood and opposite an interior suction box.

The drive of each drum is preferably obtained by means of pairs of rollers, for example shouldered, also serving for axial guidance, each pair consisting of an idler roller and a drive roller whose rotation is for example controlled by a motor mounted on its axis, the rollers preferably being provided with a coating giving a good coefficient of friction. The drive by rollers cannot lead to a deterioration of the other reception organs and in particular of those serving to seal the reception chamber and moreover it leaves the internal space of the drum entirely free which is therefore totally available for mounting the suction box.

To avoid blocking of reception by agglomerated fibers bonded to the walls of the hood, these are preferably cooled, so that the temperature of the walls is always lower than the polymerization temperature of the binder. In addition, the hood is preferably in two parts. The lower part - closest to the drums - is made up of cooled plates provided with recesses corresponding to the location of the drums. The upper part is of the rotating bat-flank type associated with cleaning devices external to the hood, so that the fibers which stick to the lower flanks are definitively evacuated from the receiving hood.

Means such as flexible curtains are also provided, guaranteeing the seal between the hood and the drum on the one hand and, between the interior suction box and the drum on the other hand, the fiber itself sufficient to seal between the drums.

It is also advantageous to provide each drum with a compressed air blowing ramp, the blown jet being directed at the outlet of the drums so as to promote the take-off of the fibers and the formation of the primitive under the drums.

Preferably, means are provided for modifying the length and the location relative to the fiberizing machines of the suction zone. These means are for example devices making it possible to rotate the caissons interiors - in this case centered on the axis of rotation of the drums - so as to move the peripheral zone of the drum opposite an internal box.

Finally, it is advantageous to associate with the receiving module, for each primitive, a drawing roller driven at a peripheral speed strictly identical to that of the horizontal conveyor which recovers the different primitives formed, the peripheral speed of the drums being very slightly adjusted. lower than the speed of the horizontal conveyor to take into account the creep of the fibers which takes place under the effect of gravity during the vertical trajectory of the primitives.

In addition, the suction boxes and the drums themselves are preferably provided with adequate cleaning and drying means, this in particular in order to avoid fouling by fine fibers.

• . figure 1 : un schéma général illustrant le principe du procédé selon l'invention,
• . figure 2 : un schéma de réalisation d'un module de réception conforme au mode de réalisation préféré de l'in­vention,
• . figure 3 : une vue en perspective d'une ligne com­portant 6 machines de fibrage et deux modules de réception conformes à la figure 2, avec un assemblage des primitifs en parallèle,
• . figure 4 : une vue identique à la figure 3 mais avec un assemblage des primitifs par des nappeurs.

Other details and advantageous characteristics of the invention are described below with reference to the appended drawings which represent:

• . FIG. 1 : a general diagram illustrating the principle of the method according to the invention,
• . FIG. 2 : an embodiment of a reception module in accordance with the preferred embodiment of the invention,
• . FIG. 3 : a perspective view of a line comprising 6 fiber-drawing machines and two reception modules in accordance with FIG. 2, with an assembly of the primitives in parallel,
• . Figure 4 : a view identical to Figure 3 but with an assembly of primitives by layers.

FIG. 1 illustrates by a schematic diagram the reception method according to the invention, for a glass wool production line comprising 3 fiberizing machines 1, 2, 3 arranged in the same row. These fibering machines 1, 2, 3 constituted for example by centrifuges rotating at high speed provided at their periphery with a large number of orifices through which the molten material - preferably glass - escapes in the form of filaments which are then drawn into fibers by a current concentric gas, parallel to the axis of the centrifuge, emitted at high temperature and speed by an annular burner. Optionally other fiberizing devices well known in the art can be used which all allow the formation of a core of fibers, centered on an axis, core formed by the drawing gases and especially the gases induced in very large quantities .

The reception of the fibers - intended to separate them from the gases - is obtained by means of an endless band 4 permeable to gases driven continuously. A hood 5 laterally delimits the fiber collection zone. The gas suction is obtained by independent vacuum chambers 5. Each fiberizing machine 1 is associated here with a box 6. The hood 5 is closed as tightly as possible and is therefore provided at the outlet of a steamroller 7 possibly ensuring a certain traction on the felt to help the 'extract from the hood.

According to the invention, each fiberizing machine "i" corresponds to a collection zone Zi, delimited from below by the endless band 4. These zones Zi are increasing with their index and are therefore all the larger as they are close to the exit.

It has been proposed a reception comprising as many boxes as fiberizing machines but insofar as the invention allows a homogenization of the depression values, it is of course without departing from the scope of the invention to use boxes common to several machines fiberizing. Ultimately, it is possible to use only one box for the entire row of machines 1, 2, 3.

Advantageously, the distance E between the machines is constant, there is therefore no increase in the induced air and therefore a lower risk of gas backflow and formation of wicks.

The trajectory represented in FIG. 1 is fictitious: in reality one operates with non-rectilinear but convex trajectories, for example elliptical, with as simplest embodiment, a circular trajectory associated with the use of drums.

Preferably, the number of fiberizing machines for a reception is equal to 3 or 4, so that for a large production line, two reception modules will be used.

An example of such a module is shown diagrammatically in FIG. 2 provided for collecting the fibers produced by 3 fiberizing machines. Under the fiberizing machines 8 are arranged two drums 10, 19 driven in reverse rotation and rotating towards each other. These drums 10, 19 are placed under a hood 11.

The hood 11 has a lower part 12, cooled by appropriate means, with recesses in the form of arcs of a circle for housing the drums. The upper part 13 can also be composed of fixed, cooled plates or better still of rotating sidewalls - of the vertical endless band type - the rear (that is to say the part external to the receiving unit) is preferably provided with cleaning means. The cooling means prevent a total blockage of reception from occurring by agglomerated fibers; the rotating bat-flanks improve the quality of the felt insofar as this prevents small tufts of fibers from forming - tufts which, without being able to cause the blocking of the installation, can still slightly harm the homogeneity felt, because when they finally peel off the wall they form in the felt areas with a higher content of binder which are identified by a darker shade giving the appearance of stains.

The tightness of the reception is critical and is preferably obtained by means of polyurethane mats.

The drums 10, 19 are placed in a pit under the fiber-drawing machines at a height calculated so that the minimum height of fiber fall is greater than 2500 mm in order to prevent the average speed of impact of the fibers on the drum calculated at the center of the torus is greater than 20 m / s. Preferably, this drop height does not exceed 5000 mm in order to avoid the formation of large tufts of fibers detrimental to the good quality of the insulating mat.

The drums 10, 19 have a peripheral surface that perforated gas permeable. They consist, for example, of two round end plates, rigid, onto which a perforated sheet is screwed, the diameter of the orifices being chosen as a function of the type of fibers produced. They are provided with centering and guiding devices, for example on rollers, their rotational drive being for example by chain or preferably by external rollers which guide the drum axially, these rollers being for example coated with polyurethane to ensure a good drum-roller friction.

In these drums are mounted internal suction boxes 14, centered on the rotation shafts of the drums and fixed for example on the manifold of a valve provided for the revision of the drum. The boxes 14 are delimited by side walls mounted for example along the radii of the drums, with an angle of for example 120 °, the boxes being able to be turned around the axis of the drums so as to modify the suction length and the location of the suction zone, in particular when the reception conditions must be modified by stopping the central fiberizing machine as explained below.

Preferably, provision is made to integrate into these boxes, elements for cleaning and drying the surface of the drums to prevent the orifices of said drums from being blocked in the long run by the finest fibers. These cleaning and drying elements are, for example, of the brush, concurrent nozzle or air ramp type for taking off the fine fibers.

As an indication, good results have been obtained with a washing assembly constituted by a nylon brush with long bristles placed inside the drum and driven in rotation by the latter and a small brush mounted outside the drum, these two brushes being optionally supplemented downstream (relative to the direction of rotation of the drum) by washing and drying nozzles preferably operating only intermittently and which cleans the surface of the drum of the binder film which is deposited at the long.

These suction boxes are connected by pipes to one or more fans capable of creating the necessary vacuum, and here not shown.

In this figure 2, one can also notice the axis 15, 16 of a lateral fiberizing machine 8 is vertical to the drum 10 respectively 9 facing it, the axis 17 of the central fiberizing machine being him coincident with the axis of the median plane of the pair of drums. This arrangement makes it possible to obtain the largest possible suction surface. Under these conditions, the diameter D of the drums must therefore be chosen equal to twice the distance E between two fiberizing machines or more precisely very slightly smaller than this in order to preserve a free space of for example 100 mm between the two rollers.

The fibers produced by the lateral fibering machines of a reception fall into the suction zones shown diagrammatically by double arrows L₁, while the fibers produced by the central machine fall on one or other of the drums, in the L₂ reception area. This zone L₂ is practically twice the length of zone L₁. This compensates - and even very broadly - the resistance to the passage of smoke from the central machine created by the fibers from the side machines and already deposited on the surface of the drum when it reaches the L₂ area.

The reception can operate with speed settings to compensate for the loss of grammage, when one of the side machines is stopped. If the stop concerns the central fiberizing machine, it is preferable to shift the suction zones to the sides so as to limit the increase in induced air generated by the central "vacuum" and above all to avoid the formation of wicks which wrap around themselves near the drums. This fiberizing possibility constitutes a very great advantage of the reception modules according to the invention, because it takes into account the operating hazards of fiberizing machines.

Quite paradoxically, a reception module conforming to the preferred embodiment of the invention enables products of higher quality to be obtained than the products capable of being obtained when two receiving drums are provided for two fiberizing machines. This can be explained by the fact that the torus from a fiberizing machine is not perfectly homogeneous; an analysis of the gas velocity profile indeed shows that the speed is maximum around the axis of rotation of the fiberizing machine and decreases on the edges of the torus. When one or only two fiberizing machines are used, an air current tangential to the surface is generated at the periphery of the receiving surface; due to the higher suction on the side parts less loaded with fibers. This tangent current drives fibers which roll on themselves and form wicks. When we increase the number of fiberizing machines while preserving a small distance between them, we obtain an isomorphic profile of depressions to the speed profile - with as a consequence a better homogeneity of the products.

Figures 3 and 4 illustrate the application of reception modules according to the invention to production lines comprising 6 fiberizing machines. FIG. 3 corresponds to a double online reception, that is to say that the 6 fiber-drawing machines are fed with molten glass by the same main channel, here with an assembly of the primitives by superposition in parallel layers.

Under the 6 fiber drawing machines 20 are arranged two receivers constituted by two pairs 22, 23 of two drums 21 moved in reverse rotation, each reception collecting the fibers produced by a group of 3 fiber drawing machines, the central fiber drawing machine of a given group being oriented along the median plane to the two drums of a reception. Each pair of drums is isolated from the other pairs of drums by a hood, the receptions are therefore independent here. Each receiving unit thus forms a basic module, reproduced as many times as necessary according to the production capacities of the line, the relative arrangement of the modules with respect to each other, however, having to take account of the means for supplying molten glass to the different fiberizing machines, that is to say the number of molten glass supply channels provided at the outlet of the melting furnace and the arrangement thereof in line as shown here, or in parallel as in FIG. 4.

The fibers collected by a given pair of drums form a primitive 24 respectively 25 which falls in a vertical plane and is then collected by a horizontal conveyor 26 of the endless non-perforated strip type located at the bottom of the pit on which are superimposed in layers 27, 28 the primitives 24, 25 from the different groups of 3 fiberizing machines. Finally, an inclined conveyor, not shown here, leads the felt formed outside the receiving pit.

During its vertical fall towards the horizontal conveyor, the pitch has a slight tendency to lengthen, all the more so as the grammage is low. To prevent the felt from forming a loop, the horizontal conveyor must therefore be driven at a speed very slightly higher than the peripheral speed of the drums; depending on the grammage, the theoretical difference to be respected is between 0 and 1%. As it is relatively difficult to operate exactly with a speed ratio corresponding to this theoretical ratio, it is advantageous to equip the installation with stretching rollers placed just above the horizontal conveyor and here not shown, these rollers d drawing most often exerting a slight pull on the felt and being driven exactly at the speed of the horizontal conveyor.

FIG. 4 corresponds to a double reception in parallel associated with an assembly of the primitives by superposition in interlaced layers.

Are thus represented reception modules 30, 31 associated with lappers 32, 33. Each module is thus associated with a pendulum movement member supplied by a conveyor belt 34, 35, so that the primitive undergoes 2 changes of direction consecutively at 90 °. The pendulum member 32 respectively 33 is constituted by two continuous bands 36, 37 between which the primitives pass. The pendulum member 32 is connected by a system of connecting rod-crank to a drive motor communicating to it a pendulum movement, so that the primitive is deposited on a conveyor 38 in the form of layers of intertwined felt, said conveyor 38 having a direction of travel perpendicular to the initial direction of the primitives . The continuous strips can also play a role of stretching the felt, a role which for receptions not provided with pendular members can advantageously be fulfilled by stretching mats or the roller 7 visible in FIG. 1. The stretching allows '' avoid accumulation of felt in the hood.

The device of FIG. 4 allows the production of products whose grammage is for example greater than 10 kg per m², while the device of FIG. 4 gives all satisfaction for the most common products whose grammage is for example close to 4000 g / m², which is already considered for a glass wool insulation product as a heavy product.

The performances of the receptions according to the invention were also verified quantitatively.

Initially, 6 fiberizing machines were used, spaced at a fixed center distance of 2000 mm, using different types of receiving modules and different numbers of modules. The following results were obtained: Test ^No. 1 2 3 4 5 6 No. of modules 1 6 1 3 1 2 drums / tape bandaged tamb. tamb. tamb. tamb. tamb. Number of drums - 12 12 6 6 4 Drum diameter (mm) - 950 950 1950 1950 2575 Smoke flow (%) 100 98 107 99 107 79 Max depression (Pa) 13140 480 550 1260 1410 1520 Power 100 22 24 29 33 52

All the tests were carried out on the same production line comprising 6 centrifuge-type fiberizing machines of 20 tonnes per day of molten glass and on a final grammage of the glass wool mattress of 2500 g / m².

The first test corresponds to a so-called strip fiber reception, which made it possible to define a reference base 100 for the total flow of smoke to be sucked in and the total power dissipated at the level of the installation. As an indication, this smoke flow of 100% corresponds to a smoke flow (drawing gas and induced gases) from 360,000 to 450,000 Nm³ / hour.

Tests 2 and 3 correspond to receptions with two drums for each fiberizing machine, these receptions being or not isolated from each other to form separate modules. The maximum depression that the felt undergoes is much lower than that of the reference test, and much lower than the value for which the first damage can be observed. The total power dissipated is also lower, but the gain is not directly comparable to that recorded at the level of depressions, this due to the greater pressure losses due to the multiplication of ancillary equipment such as pipes, washers, etc. ..

We also note that the best results are obtained with extreme modularization (6 modules for 6 fiberizing machines), which leads to the multiplication of hoods and therefore fouling zones which, if not properly cleaned, allow dust to settle or heaps of bound fibers which in turn degrade the quality of the product. When removes this modularization (test ^No. 3) is obtained in a very sharp increase in the flow of fumes - which is reflected by a slight increase of the maximum depression exerted on the felt for their suction. In addition - and what the table above does not show - the quality of the fibers is lower, with the consequence of a reduction in the insulating power of the final felt.

We find the same conclusions with tests 4 and 5 corresponding to 2 fiberizing machines for two drums, except that one should note the formation of strands of fibers which are wound on either side of the drums which cause a very clear degradation of the final quality of the felt.

By proceeding on the other hand in accordance with the invention (eesai n ^o 6), we find the same conditions from the point of view of the energy balance and again very low values of depression - while having only two reception modules and therefore a much lower initial investment.

It is finally interesting to compare two production lines, the first is a line to a traditional line, with a horizontal receiving band, but however meeting the criteria of claim 1, that is to say for which the collection areas are increasing in the direction of the increase in grammages, this growth being obtained by a progressive increase in the distances between the fiber-drawing machines; this line comprises two reception modules formed by converging receiving bands (tests 7 and 9) the second line conforms to the diagram in FIG. 3. (tests 8 and 10). Test ^No. 7 8 9 10 Drum diameter D (mm) 2575 2575 Minimum distance between 2 machines 1500 1300 1500 1300 Suction length (mm) L 2600 2653 2650 2653 Smoke flow% 100 79 100 78 Speed m / s 3.29 2.36 3.29 2.35 Maximum depression (Pa) 4890 1520 8140 2470 Total power 100% 52% 100% 45%

L represents the length of the collection zones corresponding to the highest grammages. Tests 7 and 8 concerned the manufacture of a felt with a grammage equal to 2500 g / m², tests 9 and 10 at a grammage of 4000 g / m², with in all cases 2 x 3 centrifuges through which a flow rate of 20 tonnes per day of molten glass is passed.

In both cases, dense products are easily obtained without using a lapper. However, the comparison of the speeds of the passage of gases through the felt and of the depressions or level of the areas of heavier grammage undoubtedly show the superiority of the preferred mode of the invention.

The possibility of proceeding with non-constant spacing can also be extended to the case of receptions according to the invention, corresponding to different drop heights depending on the fiberizing machines, for example in a reception scheme in accordance with FIG. the most satisfactory results are however obtained with n two drum receiving modules for 3 n fiber drawing machines.

A last advantageous aspect of the invention is that it leads to the formation of relatively cold felts, this because the primitives are cooled in the open air before being recovered by the horizontal conveyor and especially because the suction is just as effective in the area of heavy weights as in the area of low weights, which prevents the accumulation of hot gases. The products obtained according to the invention typically have a temperature at the entrance to the oven lower from 20 to 50 ° C. than that of the products according to the art, the greatest differences being observed for the heaviest products. This results in less pre-polymerization of the binder which leads to significantly improved mechanical strengths.

In addition, a lower temperature - associated with a higher initial thickness of the fibers which are not packed by the suction in the reception - bring a greater stability of the production in particular a greater constancy of thickness of the products, this which makes it possible to reduce non-functional excess thicknesses which are simply intended to guarantee the customer a given nominal thickness.

Claims (27)

1. Receiving method for the separation of fibers and gases produced by a plurality of fiberizing machines with a view to obtaining a mineral wool mattress, method according to which the fibers are collected by suction of gases, each machine fiberizing i having its own collection zone Zi, the collected fibers being removed from the collection zone by one or more of the conveyor belts common to several collection zones Zi, characterized in that the surfaces of the collection zones Zi are increasing in the direction of the increase in grammages on said conveyor belts. 2. Receiving method for the separation of fibers and gases produced by a plurality of fiberizing machines with a view to obtaining a mineral wool mattress, method according to which the fibers are evacuated by two converging conveyor belts according to claim 1, characterized in that the surfaces of the collection zones Zi are increasing in the direction of the place of final formation of the common felt. 3. Reception method according to claim 1 or 2, characterized in that the delivery rate is constant. 4. Reception method according to claim 1 or 2, characterized in that the delivery rate is zero. 5. Reception method according to one of claims 1 or 2, characterized in that the collection zones Zi are constituted by portions of conveyor belts. 6. Reception method according to one of claims 1 to 5, characterized in that the depression exerted on the felt is the same for all the collection zones Zi. 7. Reception method according to one of claims 1 to 6, characterized in that the fall heights of the fibers differ according to their original fiberizing machines. 8. Reception method according to one of claims 1 to 6, characterized in that the trajectory of the conveyor belts is convex. 9. Reception method according to one of claims 1 to 8, characterized in that the increase in the areas of the collection zones Zi is obtained by a modification of the angle of inclination of the normal to the collection surface with respect to the axis of rotation of the fiberizing machine associated with the collection surface. 10. Receiving method according to claim 9 characterized in that the increase in the areas of the collection zones Zi is obtained in addition by increasing the distance between two fiberizing machines. 11. Reception method according to one of claims 9 or 10, characterized in that the increase in the areas of the collection areas is obtained by gradually tilting the axes of rotation of the fiberizing machines. 12. Reception method according to one of the preceding claims, characterized in that a stretching operation is carried out on the primitive to aid in its extraction from the collection area. 13. Receiving method according to one of claims 1 to 12, characterized in that the fiberizing machines are divided into groups of for example 3 or 4 machines, each group of machines corresponding to a receiving module 14. Reception method according to claim 13, characterized in that said reception modules are connected in series. 15. Reception method according to claim 13, characterized in that said reception modules are mounted in parallel. 16. Method for receiving mineral fibers according to claim 14 or 15, characterized in that the primitives formed by each reception module are combined by superposition in parallel layers. 17. Method for receiving mineral fibers according to claim 14 or 15, characterized in that the primitives formed by each reception module are brought together by superimposing at least 6 layers of interlaced primitives. 18. Reception method according to claims 7 to 17, characterized in that the collection surfaces are constituted by drums. 19. Method for receiving mineral fibers known as insulation, in particular glass fibers for the purpose of separating fibers and ambient gases under the fiberizing machines to obtain a mineral wool mattress, according to which the fibers minerals are collected on rotating drum-type members, in order to form primitives collected later but before polymerization of the resin intended to bind the fibers is carried out, characterized in that one pair of drums is provided per group 3 fiberizing machines. 20. Method for receiving mineral fibers according to one of claims 18 or 19, characterized in that the minimum drop height of the mineral fibers is such that the impact speed of the fibers on the drums is less than 20 m / s . 21. A method of receiving mineral fibers according to claim 20, characterized in that said minimum drop height is between 2500 and 5000 mm. 22. Device for receiving mineral fibers known as insulation, in particular glass fibers, for the purpose of separating fibers and ambient gases under the fiberizing machines to obtain a mineral wool mattress comprising in association with each group 3 fiberizing machines, a reception formed by a hood in which are placed a pair of drums perforated over their entire peripheral surface provided with centering devices and rotary drive, interior suction boxes. 23. Device according to claim 22, characterized in that the drums and the suction boxes are provided with cleaning and drying equipment. 24. Device according to one of claims 22 to 23, characterized in that it further comprises an endless belt conveyor placed under the various drums from which it collects the primitives directly. 25. Device according to one of claims 22 to 24, characterized in that it further comprises a lapper. 26. Device according to claim 22, characterized in that each drum is driven by a pair of pebbles. 27. Device according to one of claims 22 to 26, characterized in that a drawing roller exerts a slight traction on the pitch before it is collected by the endless belt conveyor.

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