EP1322807B1 - Method and device for making mineral fibre felts - Google Patents

Abstract

A unit and process of manufacturing felts formed from crosslinked mineral fibers. The unit includes at least one pair of conveyors formed by a lower conveyor and an upper conveyor placed opposite each other and configured to compress the felt in at least one direction. A heat treating device heat treats the felt after the felt has passed through the conveyors. At least one mechanism is placed in a region between the conveyors and the heat treatment device, to prevent decompression of the felt in this region. The mechanism includes at least one cam having a profile suitable for keeping a constant and minimum distance between the conveyors and the heat treatment device, and at least one of the conveyors is rigidly connected to one element of the heat treatment device.

Description

The invention relates to the formation of felts formed from mineral fibers and designated under the generic names of glass wool, rock wool, etc.

In the traditional way, the mineral fiber felts are constituted continuously by depositing on a conveyor the fibers which are conveyed by gaseous currents. The conveyor retains the fibers and lets the gases through.

Before they are deposited on the conveyor, the fibers are coated with a composition applied in liquid form and intended to bind the fibers together, so as to give cohesion to the felt subsequently constituted. The composition is then crosslinked by a heat treatment performed on the felt which has been previously brought back to the conditions of desired thickness and density.

In addition to the insulating qualities required in a very general way, it is also sometimes necessary that the products used have very specific mechanical properties. This is the case for example products supporting masonry elements and which must therefore withstand strong compressions such as the elements used for the insulation of roof terraces. This is also the case for products used in insulation by the outside which must in particular be able to withstand the pulling forces.

In order to obtain products having these particular properties as well as others which will be discussed later, it is necessary to modify the traditional felting processes.

The formation of the felts by deposition of the fibers on the receiving conveyor or on a similar member leads to entanglement which is not homogeneous in all directions. It is found experimentally that the fibers have a strong tendency to be placed parallel to the receiving surface. This tendency is all the more accentuated as the fibers are longer.

This structure of the felts is favorable to their insulating properties and also to their tensile strength in the longitudinal direction. For many uses such a structure is therefore advantageous. However, understands that such a structure is not the most suitable when for example the product must withstand compression or tearing in the direction of its thickness.

To improve the compressive strength of these felts, one solution is to increase their density by increasing the mass of fibers per unit area on the receiving member where the felt is formed. In addition to limiting the mass of fibers per unit area that can be deposited, the accumulation of fibers on the receiving member quickly opposes the passage of gases, and therefore the pursuit in good conditions of the formation of the felt, this does not make it possible to improve other properties such as tear resistance.

Another solution proposed previously is to ensure that the direction of the fibers is no longer in the plane of the felt but in a plane perpendicular thereto. This arrangement is reached for example by forming folds in the felt. These folds are obtained in particular by arranging the felt in successive layers more or less long extending in the direction of the desired final thickness, or by compressing the felt longitudinally. Under the effect of compression under the conditions envisaged, the felt forms undulations. The heat treatment of the composition of the binder which is carried out subsequently, gives a permanent character to this pleated structure.

The direction of the fibers oriented in the direction of the thickness of the felt thus formed substantially improves the resistance to compression and tearing. This structure, however, is disadvantageous with respect to longitudinal tensile strength - felt tends to unfold - or bending.

The arrangement of the fibers in the thickness can also result from the assembly of strips of felt whose width corresponds to the thickness of the desired felt, each band being arranged so that the fibers are in planes perpendicular to the faces of the felt constituted . The strips are held against each other by means of a covering or a veil covering one or both sides of the felt. Optionally, the strips can also be glued directly to each other by their surfaces in contact.

Felts produced using this relatively complex technique, called "slats", are mainly used for pipe insulation large diameters. For this application, the bending ability and even the winding of the product obtained instead of constituting a disadvantage is particularly sought after.

A solution to this problem is described in the patent EP 0 133 083 filed in the name of the Applicant. The object of this prior invention is to provide felts in which the mechanical properties, in particular the resistance to compression and tearing in the direction of the thickness of the product, are improved without causing the disadvantages previously encountered, and consequently without forming folds, or assembling bands of felts; the mechanical and insulating properties of said felts remaining otherwise satisfactory.

To do this, we seek to obtain fibers (inside the felt) with directions as varied as possible without forming folds on the surface. According to this prior art, the felt is subjected to at least one longitudinal compression operation, and preferably to two operations of this type.

A problem related to such fabrications lies in the homogeneity of the final felt and in particular in its surface homogeneity. In fact, cracks, rupture primers and / or localized swellings are observed on the surface; as many negative defects in terms of mechanical strength, thermal not to mention the unsightly appearance of the whole.

This problem is essentially created in the area between the conveyor belts and the reticulation oven.

In this area, the felt is no longer compressed so that it tends to escape.

The aforementioned patent provides slides in this area to ensure a certain continuity in the maintenance of the felt. However the slides are then additional elements, fragile, especially as they are placed in the immediate vicinity of the oven which is hot. In addition, they must be perfectly positioned to ensure the desired continuity. In fact, this solution is not viable and the slides pose more problems than they solve; this is why in practice this solution has been abandoned in favor of another solution, which constitutes the object of the present application.

The present invention advantageously consists in a reliable solution, simple and that perfectly solves the problem mentioned above.

Thus, the subject of the present invention is a set of manufacturing of felt made of crosslinked mineral fiber fibers comprising at least one pair of conveyors formed of a lower conveyor and an upper conveyor arranged in facing relation and intended to compress said felt in at least one direction, a heat treatment means of the felt after passing through the conveyors.

According to the invention, the assembly further comprises at least one means disposed between the conveyors and the heat treatment means, intended to prevent the decompression of the felt in this zone, as well as any mechanical interference, said means comprising at least one profile cam adapted to maintain substantially constant and minimal the distance between the conveyors and the heat treatment means; at least one of the conveyors is rigidly connected to an element of the heat treatment means.

In particular, at least one of the conveyors is held in abutment against said cam by means such as cylinders.

Specifically, the cam is rigidly connected to an element of the heat treatment means, said element being movable vertically and / or horizontally. Horizontal displacement compensates for thermal expansion.

According to one embodiment of the invention, the lower conveyor is rigidly connected to an element of the heat treatment means by means of a connecting means.

According to one embodiment of the invention, said cam has a curve portion of curvature substantially identical to that of a wheel of the heat treatment means, placed vis-a-vis.

More specifically, the cam further has a straight portion disposed vertically below the curved portion and serves as support for the upper conveyor.

Advantageously, the upper conveyor, the cam and the element of the heat treatment means to which it is connected are movable vertically in order to be able to manufacture felts of different thicknesses.

The invention furthermore relates to a method for producing felts made of glued fibers, made of mineral material, notably comprising compressing the fibers in at least one direction and then heat-treat the felts to stabilize them.

Typically, the method further comprises preventing the decompression of the felt between the compression step and the heat treatment step, by means of a profile cam adapted to maintain substantially constant and minimal the distance between the compression means and heat treatment means.

Specifically, the compression means are held in abutment against said cam.

As an illustration, longitudinal compression and / or compression is made in the thickness of said felt.

The present invention advantageously allows the manufacture of felts with a thickness of between 10 and 500 mm.

The minimum distance between the compression means and the inlet of the oven is of the order of 5 mm.

• la figure 1 est un schéma d'implantation d'une installation de fabrication de feutres comprenant un ensemble selon l'invention ;
• la figure 2 est une vue partielle d'une installation comprenant un ensemble selon l'invention ;
• la figure 3 est un schéma de l'ensemble selon l'invention dans plusieurs cas de fonctionnement.

Other features, details, advantages of the invention will appear better on reading the following description, given by way of illustration, and in no way limiting, with reference to the appended drawings in which:

• the figure 1 is a layout diagram of a felt manufacturing facility comprising an assembly according to the invention;
• the figure 2 is a partial view of an installation comprising an assembly according to the invention;
• the figure 3 is a diagram of the assembly according to the invention in several cases of operation.

The figure 1 describes the global context in which the present invention may advantageously be implemented.

This figure schematically shows a manufacturing line of felts 6 formed of mineral fibers also called rock wool or glass wool. In known manner, such a line comprises one or more centrifugation devices 1 for forming fibers 2 which are projected from the centrifugation device (s) 1 into a receiving chamber 3 at the base of which is disposed a conveyor 4 on which fall the fibers.

Preferably, one or more caissons 5 under vacuum are located under the conveyor 4 in order to suck up and pile up the fibers on the conveyor 4.

A carpet or felt 6 is thus formed; it is taken out of the chamber 3 between two conveyors 7, 8 for compressing it according to its thickness.

Then the felt 6 is compressed longitudinally by passing between pairs of upstream conveyors 9, 10 and downstream 11, 12 whose speeds are such that the speed of a pair 11, 12 is less than the speed of the upstream pair 9, 10 (relative to the movement of the felt 6 through the conveyors).

Once compressed, the felt 6 is directly introduced into an oven 13 where a heat treatment ensures the crosslinking of the binder and the stabilization of the product. Other heat treatments may be envisaged without departing from the scope of the present invention.

Moreover, at the outlet of the oven, the felt can be cut, conditioned according to the intended uses.

The problem at the origin of the invention lies at the outlet of the downstream conveyors 11, 12, before the introduction of the felt 6 in the oven 13.

Indeed, at this level, the felt 6 is highly compressed, its density is commonly of the order of 100 kg / m ³ , so that it has a tendency to escape in the gap left free between the downstream conveyors , 11, 12 and the oven 13.

As already mentioned, various solutions have been proposed to remedy this problem.

The present invention illustrated in more detail on the figure 2 , solves in a new, inventive and unexpected way such a problem.

In this figure appear in particular the downstream conveyors 11, 12 and the felt 6 which is moved between the conveyors in the direction of the arrow.

The oven 13 is symbolically limited by dots.

Between the conveyors 11, 12 and the oven 13 is disposed according to the invention a means 14 for preventing the decompression of the felt 6 in this area, the means 14 comprising at least one cam whose profile is adapted to maintain constant and minimal the distance between the conveyors 11, 12 and the oven 13.

To do this, the upper conveyor 12 is held in abutment against the cam 14 for example by cylinders (not shown) themselves actuated by one or more motors (not shown). This arrangement makes it possible to absorb a dilation of the different elements. The cylinders also make it possible to maintain the conveyor chain tensioned whatever the position of operation. In addition, the upper conveyor 12 is vertically movable making it possible to manufacture different thicknesses of felt 6.

The cam 14 is preferably rigidly connected to a fixed element of the oven (not shown), which can however be moved vertically, depending on the thickness of the felt to be manufactured.

At the lower downstream conveyor 11, cylinders (not shown) may also be provided in order to push said conveyor 11 against the cam 14 and / or maintain it at the same level as the belt located in the oven 13.

Moreover, the lower conveyor 11 is itself rigidly connected to a fixed element of the oven, by a connection symbolized at 18.

Other features of the invention will be understood on reading the figure 3 which shows the upper downstream conveyor 12 in three possible positions (a), (b), (c). The lower downstream conveyor 11 is only slightly adjustable in height; the amplitude of its vertical displacement is only intended for the adjustment vis-à-vis the conveyor belt (not referenced) of the oven 13.

For positions (a) and (b) which correspond to operating positions, the cam 14 is itself in a first position shown in solid lines.

These positions correspond to the minimum and maximum thicknesses of the felt that can be manufactured.

Position (c) is a position of maximum spacing between the conveyors. It is a maintenance position for which the cam 14 is in position C2 and the upper roll of the oven 13 in position C1.

In all cases, the upper downstream conveyor 12 is pushed against the cam 14 which, being rigidly connected to an element such as the upper roller of the oven 13, thus makes it possible to maintain the conveyor 12 at a constant distance from said roller . The profile of the cam 14 further allows to maintain the upper conveyor 12 at a minimum distance from the oven 13 regardless of the thickness of the felt 6 to be treated.

This profile comprises a vertical straight portion 141 surmounted by a curved portion 142 whose curvature is close to or identical to that of the upper roll of the oven 13. The straight portion 141 may extend over the height of the end zone the upper conveyor 12 in the lower position and the height of the end zone of the lower conveyor 11.

Of course, this profile is given here as an illustration and other cam profiles can be used without departing from the scope of the invention, provided they fulfill the function stated above, maintaining the position of minimum separation vis-à-vis the oven 13.

By way of illustration, the density of the felt upstream of the conveyors 11, 12 is of the order of 10 kg / m ³ . At the entrance to the oven 13, it is commonly between 10 and 200 kg / m ³ .

The thickness of the felt at the entrance of the conveyors 9, 10 is between 240 mm and 1200 mm; finally, that is to say at the entrance of the oven 13 the thickness of the felt may be between 20 and 300 mm. The final product may have a thickness of between 10 and 500 mm.

The fibers can be of a very variable length; their diameter is between 3.5 microns and 5 microns.

The speed of conveyor belts can be between 1.5 and 40 m / min.

The figure 4 represents in perspective the upper downstream conveyor 12. This conveyor is shown alone, and the side intended to supply felt oven, the latter is not shown. This conveyor comprises a metal mesh mat 41 which comes into direct contact with the felt to convey it, said mat being itself driven by a non visible cake on the figure 4 but that we guess under the carpet and placed in the axis X-X ', said cake including gear wheels, one of which is driven by a transmission chain 42, said chain being itself driven by an engine 44 fixedly connected with the frame 45 of the conveyor. Two cylindrical support rollers 43 (for example 120 mm in diameter) are fixed on the frame and on both sides thereof. The circumference of each roller can freely rotate about the axis of the roller (ie the X-X 'axis). It is these rollers which are intended to come into contact with cams 14 according to the invention. The fact that the circumference of the rollers is free in rotation limits the friction when the position of the conveyor is changed in the vertical direction and while the rollers bear on the respective cams.

The figure 5 represents in perspective a part of the device intended to receive the felt from the downstream conveyors and a part of which has been represented by the figure 4 . We have not represented on this figure 5 that part left of the upper receiving roll of the oven. We must imagine that there is an equivalent and symmetrical right part of the left part. For the sake of simplicity, in the context of the present application, the end portion of the conveying device receiving the felt from the downstream conveyors is called a roll. As we see on the figure 5 Perforated metal pallets (in English: perforated lamellas) 51 receive the felt to drive it into the oven. These pallets are driven by a cake not visible in the figure but that is guessed under the pallets and in the axis of the roller, said cake including gear wheels 52 driving a link chain 53 and rollers 54, the pallets being fixed to said chain. We see on the figure 5 a cam 14 according to the invention and intended to receive the support rollers 43 seen on the figure 4 . This cam is fixed and fixedly connected to the chassis of the oven. Another cam, placed symmetrically thereto, exists on the right side of the device, not shown on FIG. figure 5 . This other cam is intended to receive the support roller 43 left represented on the figure 4 . By way of example, these cams can have for width ("x" on the figure 5 ) 40 mm.

Claims (12)

1. A unit for manufacturing felts (6) which are formed from crosslinked mineral fibers, comprising at least one pair of conveyors formed by a lower conveyor (11) and an upper conveyor (12) which are placed opposite each other and intended to compress said felt (6) in at least one direction, a means (13) for heat treating the felt (6) after it has passed through the conveyors (11, 12) characterized in that it furthermore includes at least one means (14) placed between the conveyors (11, 12) and the heat treatment means (13), intended to prevent decompression of the felt (6) in this region, said means comprising at least one cam (14) having a profile suitable for keeping a constant and minimum distance between the conveyors (11, 12) and the heat treatment means (13), and in that at least one of the conveyors is rigidly connected to one element of the heat treatment means (13).
2. The unit as claimed in claim 1, characterized in that at least one of the conveyors (11; 12) is kept pressed against said cam (14) by means such as cylinders.
3. The unit as claimed in either of claims 1 and 2, characterized in that the cam (14) is rigidly linked to one element of the heat treatment means (13), said element being able to move vertically and/or horizontally.
4. The unit as claimed in one of the preceding claims, characterized in that the the lower conveyor (11) is rigidly connected to one element of the heat treatment means (13) via a linking means (18).
5. The unit as claimed in one of the preceding claims, characterized in that said cam (14) has a curved portion (142) of curvature substantially identical to that of a wheel of the heat treatment means (13), said wheel being placed opposite the cam.
6. The unit as claimed in claim 5, characterized in that the cam (14) furthermore has a straight portion (141) lying vertically below the curved portion (142) and in that the cam (14) bears on the upper conveyor (12).
7. The unit as claimed in any one of claims 3 to 6, characterized in that the upper conveyor (12), the cam (14) and the element of the heat treatment means (13) to which it is linked can move vertically so as to be able to manufacture felts (6) of different thicknesses.
8. A process for manufacturing felts (6) formed from sized mineral fibers, consisting in particular in compressing the fibers in at least one direction and then in heat treating the fibers so as to stabilize them, characterized in that it furthermore consists in preventing decompression of the fibers (6) between the compression step and the heat treatment step, by means of a cam (14) having a profile suitable for keeping a constant and minimum distance between the compression means (11; 12) and the heat treatment means (13).
9. The process as claimed in claim 8, characterized in that at least one of the compression means (11; 12) is kept pressed against said cam (14).
10. The process as claimed in either of claims 8 and 9, characterized in that said felt (6) is compressed longitudinally and/or in the thickness direction.
11. The process as claimed in either of claims 8 and 9 for manufacturing felt (6) having a thickness of between 10 and 500 mm.
12. The process as claimed in one of claims 8 to 11, characterized in that the minimum distance between the compression means (11, 12) and the inlet of the oven (13) is about 5 mm.

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