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EP 0 725 714 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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28.07.1999 Bulletin 1999/30 |
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Date of filing: 09.09.1994 |
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International application number: |
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PCT/FI9400/396 |
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International publication number: |
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WO 9507/169 (16.03.1995 Gazette 1995/12) |
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METHOD FOR THE MANUFACTURE OF A MAT-LIKE PRODUCT
VERFAHREN ZUM HERSTELLEN EINES MATTENÄHNLICHEN GEGENSTANDES
PROCEDE DE FABRICATION D'UN PRODUIT DE TYPE MAT
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Designated Contracting States: |
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AT BE CH DE DK FR GB IT LI NL SE |
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Priority: |
09.09.1993 FI 933962
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Date of publication of application: |
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14.08.1996 Bulletin 1996/33 |
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Proprietor: VALMET CORPORATION |
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00620 Helsinki (FI) |
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Inventor: |
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- NIEMINEN, Jorma
FIN-38700 Kankaanpää (FI)
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Representative: Hakola, Unto Tapani |
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Tampereen Patenttitoimisto Oy,
Hermiankatu 6 33720 Tampere 33720 Tampere (FI) |
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References cited: :
WO-A-82/03359 US-A- 5 143 680
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WO-A-93/24290
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] The present invention relates to a method as set forth in the preamble of the appended
claim 1 for the manufacture of a mat-like product.
[0002] International publication No. WO 82/03359 discloses a method for making a moldable
mat from wood fibers such that the wood fibers are intertwined with thermally bondable
binder fibers which bond the fibers together upon melting and setting. The mat is
formed by using a so-called dry process on a moving belt by means of an air flow,
which transports the fibers onto the belt and travels through the mat. This is followed
by a mat bonding process by carrying the thus formed mat through an oven, having a
sufficiently high temperature for softening the binder fibers, which are of thermoplastic
plastics material, and bringing them in an adhesive state for bonding the wood fibers
to each other.
[0003] The use of wood fibers and other cellulosic fibers of vegetable origin for manufacturing
products made of fibers is attractive in the sense that the question is about reclaimable
natural raw materials, which are abundantly available, pleasant to handle as a material,
and do not create health hazards. A fibrous mat manufactured from these fibers is
also an effective heat insulation. However, this is the very feature that causes a
problem in manufacturing the product, if the above process is to be employed. When
treating the product in an oven, it is namely necessary to give the oven a considerable
length for heat to penetrate also in the interior of a mat-shaped product for bonding
the fibers. If the purpose is to manufacture products of considerable thickness, it
would be necessary to make the ovens unreasonably long for bonding the mat properly
also in its middle sections upon leaving the oven. Another alternative would be a
drastic increase of temperature which would, however, lead to damages in the surface
structure of a product, since the thermoplastic fibers included therein would then
melt or fuse completely away as globular drops not capable of bonding the fibers together
and the mat would break up. It is obvious that the above processes are not feasible
in terms of energy consumption, either.
[0004] For eliminating this drawback, Finnish Patent Application No. 922421, corresponding
to EP-B-601142 which in turn corresponds to prior art according to Art. 54(3) EPC,
discloses a method as well as an apparatus, by means of which it is possible to manufacture
even very thick fibrous mats of wood fibers having an excellent heat insulation capability.
Here thermoplastic binder fibers acting as heat-activatable binder material and intertwined
with vegetable-based cellulosic fibers are activated, i.e. softened already in an
air flow carrying the fibers to a forming platform by setting the temperature of the
air flow sufficiently high. The heat insulation properties of the fibers will thereby
not be detrimental. Thermoplastic binder fibers bond wood fibers to each other already
at the manufacturing stage of a mat. In practice, this facilitates the manufacture
of even a very thick mat, since fresh fibers bonding into a mat can be stacked basically
in quantities as large as may be desired on top of a mat previously formed at the
manufacturing site of a mat.
[0005] The above-mentioned method is restricted to the use of cellulosic fibers. Now it
has been discovered that the method is also suitable for manufacturing such products
where instead of the cellulosic fibers which are not activatable by heat, the base
material forming the mat can be constituted of particles activatable at a higher temperature
than the binder material, such as of mineral fibers ("rock fibers" and glass fibers)
or other thermoplastic fibers.
[0006] The invention will now be described in more detail with reference made to the accompanying
drawings, in which
- fig. 1
- is a cut-away side view of a mat forming assembly included in an apparatus used in
the method of the invention,
- fig. 2
- is a cut-away plan view of the assembly shown in fig. 1,
- fig. 3
- is a larger-scale view of a detail included in the assembly shown in fig. 1.
- fig. 4
- illustrates schematically the operating principle for an entire apparatus.
[0007] Fig. 1 illustrates a mat forming assembly, including a feeding mechanism 11 for separate
particles. The feeding mechanism may comprise either a per se known vertical device
11a for bringing the particles by means of an air flow, or a horizontal conveyor 11b,
whose inlet end can be provided with per se known pretreating means. The bottom end
of feeding mechanism 11 is provided with a feeding roll 2 having pins on its surface
in a dense pattern. Facing towards the surface of feeding roll 2 is a horizontal narrow
slit orifice at the end of a first air conduit 3. Below the slit orifice is located
an inlet for a second air conduit 4, with a constriction point formed between its
bottom wall and the surface of feeding roll 2. Downstream of this constriction point
there is an obliquely declining, expanding air chamber 6, having its lower end closed
with an air permeable forming platform 1. On the opposite side of forming platform
1 lies a collecting chamber 10.
[0008] The forming platform 1 is formed of an endless belt, extended around cylinders and
adapted to travel across chamber 6. Downstream of chamber 6 said forming platform
travels across a second air chamber 8, providing a bottom surface therefor.
[0009] The inlet end of first air conduit 3 is provided with mutually parallel fans 12 for
producing a uniform air flow across the entire width of duct 6. These fans 12 are
shown by dash lines in fig. 2. A duct serving as the inlet end of second air conduit
4 is also provided with a fan 13, which is adapted to blow air heated by a heater
7 into said second air conduit 4. Heater 7 can be for example a conventional gas burner.
[0010] The mat-forming process in the apparatus is such that separate particles forming
base structure of the mat, which have been manufactured earlier, are delivered by
means of the feeding mechanism towards feeding roll 2. Fig. 4 shows the subsequent
mat-forming process in more detail. The rotating feeding roll 2 includes pins 2a,
indicated in the figure as the outermost layer of the feeding roll, for picking up
and carrying the particles further. In the rotating direction of the feeding roll,
the fibers arrive next in the range of action of a horizontal slit orifice 3a, located
at the end of first air conduit 3 and extending across the width of said roll. A high-speed
air flow A1 discharging from the slit orifice disengages the particles from feeding
roll 2 while rushing along the roll surface and carries them across the inlet 4a of
second air conduit 4 into a constriction point 2b between the bottom wall of said
inlet 4a and the surface of feeding roll 2. After the constriction point, the particles
are completely disengaged from feeding roll 2 and proceed into an air chamber 6, having
a cross-section which expands in their advancing direction and having a width which
is constant and corresponds to the width of a mat to be manufactured. The expansion
or flare of the chamber is achieved in a manner such that the front and rear walls,
extending in the axial direction of feeding roll 2, i.e. in the lateral direction
of a mat being manufactured, diverge from each other.
[0011] Said second air conduit 4 is used for delivering air as an air flow A2 into said
inlet 4a. The temperature of this second air flow A2 is higher than that of said first
air flow A1 supplied through said first air conduit 3. As a result of the ejector
effect produced by constriction point 2b, this air flow A2 merges into air flow A1
and blends therewith for an air flow A carrying particles to the outlet end of air
chamber 6. The supply rate of this higher-temperature air flow A2 is arranged to be
such that the temperature of air flow A carrying the particles in air chamber 6 is
sufficient to cause the activation of a thermally activatable binder material blended
with the particles to a degree that makes it capable of bonding the particles into
a mat. However, this temperature is lower than the activation temperature of the separate
particles forming the base of the mat, such that essential changes do not occur in
this material. This thermally activatable binder material is well exposed to the action
of air, since they travel in the air flow in bare condition either as separate binder
particles, such as binder fibers, or incorporated in the particles on the surface
of the material forming the base of the mat. The outlet or trailing end of air chamber
6 is closed by a forming platform 1, which travels across the chamber and can be a
woven wire fabric or a like air-permeable flat piece of material. The particles hitting
the bottom at the inlet of a conveyor, i.e. downstream of the air chamber front wall,
immediately build up a bonded mat and an identically bonded mat of a continuously
increasing thickness begins to gather on top of that. Since the resulting mat is porous
in nature, said air flow A is able to progress through the mat and said forming platform
1 therebelow into a collecting chamber 10 on the opposite side.
[0012] Fig. 1 illustrates the subsequent processing of a mat. Downstream of chamber 6 in
the traveling direction of forming platform 1 is mounted a packing cylinder 14, whose
distance from forming platform 1 is adjustable. The packing cylinder prevents the
passage of air in the traveling direction of forming platform 1 out of the air chamber
from above the mat. Downstream of the packing cylinder, said forming platform 1 carries
the mat into a second air chamber 8 located above forming platform 1. The top end
of air chamber 8 is provided with an air conduit 9. The second air chamber 8 has a
flaring or expanding configuration towards forming platform 1 in the flowing direction
of an air current supplied from air conduit 9, i.e. the chamber walls located on the
inlet and outlet side of the forming platform are diverging from each other. For example,
the pressure of an air flow B supplied into the chamber can be applied for further
compressing the mat to a desired degree for providing a desired value for its density.
Thus, the air flow is delivered through the porous mat and the forming platform 1
supporting it from below and into a second collecting chamber 15 located on the opposite
side. Thus, said air flow B supplied into second air chamber 8 has such a temperature
that the binder fibers still remain in a softened state where the fibers allow the
deformation of the mat for shaping or molding the mat to a desired density such that
the deformation is permanent. Downstream of second chamber 8, the mat is transferred
from forming platform 1 onto a conveyor 16 for carrying the bonded mat-shaped product
forward for further processing.
[0013] If a product of a particularly low density is desired, the further processing effected
by means of second air chamber 8 can be omitted. The product density can also be controlled
already during a mat-forming operation by means of the flow rate of air current A
advancing in air chamber 6, said flow rate dictating the force by which the fibers
strike into a mat configuration.
[0014] Fig. 4 illustrates schematically one possible arrangement for air flows in the invention.
The air currents are circulated such that the mat-forming air flow or current A arriving
in collecting chamber 10 is delivered by way of fan 12 into first air conduit 3. During
this period the air flow has time to cool to such a degree that the first air flow
A1 discharging from air conduit 3 through slit orifice 3a is below the temperature
capable of bringing the binder material to an activated state. Thus, this air flow
A1 only serves for detaching the particles from feeding roll 2. However, it can be
used for providing a preheating, whereby the air flow A2 discharging from air conduit
4 need not be given a particularly high temperature. Said air flow A2 is delivered
into second air conduit 4 from heater 7 by means of fan 13. The air conduit 4 branches
for an air conduit 9 connected to second air chamber 8, whereby some of the heated
air flow A1 blown by the fan is extracted as an air flow B performing the further
processing of a mat. This also secures that in the further processing said air flow
B has a sufficiently high temperature and, since it originates from air conduit 4,
which only contains the flow of heated air, its temperature is in fact higher than
that of air chamber 6. However, this air does not harm the material, as it is less
exposed to it, surrounded by the mat base material contained in the articles and,
on the other hand, the flow rate of air per unit area remains quite low due to the
extent of chamber 8.
[0015] The air flow B received in second collecting chamber 15 on the other side of forming
platform 1 is circulated back to heater 7 by way of an air conduit 18. The chamber
8 also receives air carried along with a mat from chamber 6. This air advances through
collecting chamber 15 merging with the return air flowing to heater 7. In order to
maintain the air balance, some of the air progressing in first air conduit 3 is delivered
out along a duct 17. This is compensated for by delivering to heater 7 not only circulated
air but also compensation air from outside. Air can also be circulated from duct 17
to heater 7, but this degree of circulation is determined by impurities accumulated
in the air during the mat manufacturing process.
[0016] Fig. 4 further illustrates normal measuring and regulation equipment for setting
the temperatures of air flows as desired.
[0017] All possible product forms are conceivable for the product manufactured in accordance
with the invention, starting from a flexible mat to a stiff plate, in a wide range
of grammages.
[0018] All particles activatable at a certain temperature to a state where they become bonded
to each other can be applied in the method as the particles forming the base structure
of the mat. Such particles can be fibers which have been originally manufactured of
a molten material, such as mineral melt ("rock fibers" i.e. rock wool fibers, and
glass fibers), or thermoplastic plastics material. The density of the mat can be influenced
by selection of the fiber grade and ratios. It is, nevertheless, possible to use also
particles of other kind which can be made to form a mat by means of an air flow.
[0019] One example of the thermally activatable binder material that can be used is thermoplastic
material, such as thermoplastic polymer, of which can be mentioned polypropylene and
polyester. The thermoplastic material is activated to a bonding state when it softens
under the influence of heat. It is also possible to employ bicomponent material containing
polymer softening at a lower temperature on the surface of the particles. Such particles,
for instance bicomponent fibers, can be used either as the binder material for binding
other particles, which form the base, or as the particles themselves forming the base,
whereby their material activatable at the higher temperature serves as the mat base
forming material.
[0020] The temperature of air current A flowing in air chamber 6 can be set according to
the activating point of a binder material and this point, at which the binder material
softens to an adhesive or tacky state, is within the range of 100...200°C on the most
commonly used thermoplastic polymer materials. The activating temperature of the material
forming the base is higher than this. It is thus possible to employ a higher-melting
thermoplastic material as the base material and a lower-melting thermoplastic material
as the binder material. The mat structure can also be controlled by selecting the
proportions between the thermoplastic binder material and base material. The basic
raw material for the structure of the product consists of the base material, which
preferably makes up most of the total mass of a mat.
[0021] The resulting mats can have weights per unit area within the range of 40 g/m
2 - 3000 g/m
2, and their densities can range from 18 kg/m
3 to 400 g/m
3.
[0022] The products obtained can be used, depending on the kinds of particles and the mat
thickness and stiffness, for various applications, such as heat insulation, filters,
lining of various interiors such as buildings and vehicles, etc. The product can also
be used for various applications in the form of a half-fabricate that can be pressure-molded
again by heat. The obtained products can also be after-treated for improving some
properties.
1. A method for the manufacture of a mat-like product, wherein an air flow (A) is used
for forming a mat from separate particles on an advancing forming platform (1) and
the particles are bonded to form the mat by means of thermally activatable binder
material brought to the mat forming site such that it upon being activated through
the action of heat bonds the particles to each other in the mat, said material being
brought to an activated state already in said air flow (A) carrying the particles
onto forming platform (1) by setting temperature of the air flow sufficiently high,
wherein the material forming the base of the mat in the particles is constituted of
a material activatable at a higher temperature than the thermally activatable binder
material.
2. A method as set forth in any of claims 1-6, characterized in that the binder material is on the surface of the particles brought to the mat
forming site.
3. A method as set forth in claim 2, characterized in that the particles are bicomponent fibers, where the binder material is on the
surface of the fibers.
4. A method as claimed in claim 1, characterized in that the binder material is in the form of particles that are separate from the
mat forming particles.
5. A method as claimed in claim 4, characterized in that the separate particles are base fibers forming the base material of the mat,
and the particles of the binder material are binder fibers.
6. A method as set forth in any of claims 1-5, characterized in that the separate particles introduced towards the mat forming site first by means
of a first air flow (A1) which is thereafter supplemented by a higher-temperature
second air flow (A2), as a result of which the temperature of a combined air flow
(A) produced by said air flows (A1, A2) increases such that the binder material is
brought to an activated state.
7. A method as set forth in any of claims 1-6, characterized in that, after being formed by means of the air flow (A) on forming platform (1),
said mat is processed further by delivering a flow (B) of gaseous medium through the
mat while the mat is supported from the side opposite to the flowing direction of
the air flow.
8. A method as set forth in claim 7, characterized in that the further processing comprises increasing the mat density by means of a
pressure produced by an air flow (B) against the mat.
9. A method as set forth in any of claims 6-8, characterized in that the first air flow (A1) and said higher-temperature second air flow (A2)
are supplied along their own air conduits (3, 4) and the air flows are circulated
such that, after flowing through forming platform (1), some of the air flow (A) having
accomplished the formation of the mat is delivered into the air conduit (3) of the
first air flow (A1) for preheating the air flow.
10. A method as set fort in any of claims 7-9, characterized in that some of the higher-temperature air flow (A2) progressing in the air conduit
is delivered to the aftertreatment of the mat, whereby that flow makes up at least
some of the air flow (B) delivered through the mat.
1. Verfahren zur Herstellung eines mattenähnlichen Gegenstandes, wobei ein Luftstrom
(A) zur Bildung einer Matte aus einzelnen Teilchen auf einer sich fortbewegenden Aufbauplattform
(1) verwendet wird und wobei die Teilchen zur Bildung der Matte mittels thermisch
aktivierbaren Bindungsmaterial gebunden werden, das an die Mattenbildungsstelle so
gebracht wird, daß es, nachdem es durch Wirkung von Wärme aktiviert worden ist, die
Teilchen in der Matte miteinander verbindet, wobei das genannte Material bereits im
Strom (A), welcher die Teilchen auf die Aufbauplattform (1) bringt, in den aktivierten
Zustand gebracht wird, indem die Temperatur des Luftstroms genügend hoch angesetzt
wird, wobei das Material, das den Grundstoff der Matte in den Teilchen bildet, aus
einem Material besteht, das bei einer höheren Temperatur als das thermisch aktivierbare
Material aktivierbar ist.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Bindungsmaterial sich auf der Oberfläche der Teilchen befindet, die an die
Mattenbildungsstelle gebracht werden.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß die Teilchen bikomponente Fasern sind, in welchen das Bildungsmaterial sich
auf der Oberfläche der Fasern befindet.
4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Bindungsmaterial aus von den Mattenbildenden Teilchen getrennte Teilchen
besteht.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß die einzelnen Teilchen Grundfasern sind, die den Grundstoff der Matte bilden,
und die Teilchen des Bindungsmaterials Bindungsfasern sind.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die einzelnen Teilchen zuerst mit Hilfe eines ersten Luftstromes (A1) zur Mattenbildungsstelle
geführt werden, dem danach ein zweites Luftstrom (A2) mit höherer Temperatur zugeführt
wird, derart, daß die Temperatur des kombinierten Luftstromes (A) aus den genannten
Strömen (A1, A2) soweit steigt, daß das Bindungsmaterial in den bindenden Zustand
gelangt.
7. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die Matte, nachdem sie sich unter dem Einfluß des Luftstromes (A) auf der Aufbauplattform
(1) gebildet hat, nachbehandelt wird, indem man einen Luftstrom durch die Matte führt,
wobei die Matte auf der der Strömungsrichtung des Luftstromes entgegengesetzten Seite
getragen wird.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß die Nachbehandlung eine Verdichtung der Matte bewirkt infolge des Druckes eines
Luftstromes (B) auf die Matte.
9. Verfahren nach einem der Ansprüche 6 bis 8, dadurch gekennzeichnet, daß der erste Luftstrom (A1) und der genannte zweite Luftstrom (A2) mit höherer
Temperatur durch eigene Luftkanäle (3, 4) zugeführt werden, daß diese Ströme so zirkulieren,
daß ein Teil des Luftstromes (A), der die Matte gebildet hat, nach Strömung durch
die Aufbauplattform (1) in den Luftkanal (3) des ersten Luftstromes geleitet wird,
um diesen Luftstrom vorzuwärmen.
10. Verfahren nach einem der Ansprüche 7 bis 9, dadurch gekennzeichnet, daß ein Teil des Luftstromes (A2) mit höherer Temperatur, welcher durch den Luftkanal
strömt, der Nachbehandlung der Matte zugeführt wird und zumindest einen Teil des Luftstromes
(B) ausmacht, welcher die Matte durchsetzt.
1. Procédé de fabrication d'un produit de type mat, dans lequel un courant d'air (A)
est utilisé pour former un mat à partir de particules individuelles sur une plate-forme
de formation (1) qui avance et les particules sond collées pour former le mat au moyen
d'un matériau liant thermiquement activable introduit dans la zone de formation de
mat de telle façon que, lorsqu'il est activé par l'action de la chaleur, il colle
les particules les unes aux autres dans le mat, ledit matériau étant amené à un état
activé déjà dans ledit courant d'air (A) portant les particules sur la plate-forme
de formation (1) en ajustant la température du courant d'air à la valeur suffisamment
élevée, dans lequel le matériau constituant la matière de base du mat dans les particules
est constitué d'un matériau qui est activable à une temperature plus elevée que le
matériau liant thermiquement activable.
2. Procédé selon la revendication 1, caractérisé en ce que le matériau liant se trouve sur la surface des particules introduites dans
la zone de formation de mat.
3. Procédé selon la revendication 2, caractérisé en ce que les particules sont des fibres à deux constituants, dans lesquelles le
matériau liant se trouve sur la surface des fibres.
4. Procédé selon la revendication 1, caractérisé en ce que le matériau liant est sous forme de particules qui sont séparées des particules
formant le mat.
5. Procédé selon la revendication 4, caractérisé en ce que les particules séparées sont des fibres de base formant la matière de base
du mat, et les particules du matériau liant sont des fibres de liaison.
6. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce que les particules individuelles sont d'abord introduites vers la zone de formation
de mat au moyen d'un premier courant d'air (A1) qui est, après cela, complété par
un second courant d'air (A2) à une température supérieure, à la suite de quoi la température
du courant d'air combiné (A) produit par lesdits courants d'air (A1, A2) augmente
de telle façon que le matériau liant est amené à un état activé.
7. Procédé selon l'une quelconque des revendications 1 à 6, caractérisé en ce que, après avoir été formé au moyen du courant d'air (A) sur la plate-forme
de formation (1), ledit mat est traité en outre en amenant un courant d'air (B) pour
traverser le mat alors que le mat est supporté du côté opposé à la direction de circulation
du courant d'air.
8. Procédé selon la revendication 7, caractérisé en ce que le traitement supplémentaire comprend l'augmentation de la densité du mat
au moyen d'une pression produite par un courant d'air (B) contre le mat.
9. Procédé selon l'une quelconque des revendications 6 à 8, caractérisé en ce que ledit premier courant d'air (A1) et ledit second courant d'air à température
plus élevée (A2) sont amenés au long de leurs propres conduits d'air (3, 4) et que
les courants d'air circulent de telle façon que, après la traversée de la plate-forme
de formation (1), une partie du courant (A) utilisé pour la formation d'un mat est
amenée dans le conduit d'air (3) du premier courant d'air (A1) pour préchauffer ledit
courant d'air.
10. Procédé selon l'une quelconque des revendications 7 à 9, caractérisé en ce qu'une partie du courant d'air à température plus élevée (A2) progressant dans
le conduit d'air (4) est amenée jusqu'au traitement suivant d'un mat, grâce à quoi
ce courant constitue au moins une partie du courant d'air (B) qui traverse le mat.