WO2008145356A1

WO2008145356A1 - Method and apparatus for production of a mineral wool product, and mineral wool product produced therewith

Info

Publication number: WO2008145356A1
Application number: PCT/EP2008/004250
Authority: WO
Inventors: Malte Kestner
Original assignee: Saint Gobain Isover
Priority date: 2007-05-30
Filing date: 2008-05-28
Publication date: 2008-12-04
Also published as: DK2167716T3; ES2602293T3; EP2167716A1; DE102007024968A1; PL2167716T3; EP2167716B1; SI2167716T1

Abstract

The invention relates to a method for production of a mineral wool product, in which a raw unbonded web (3) composed of mineral wool provided with an unhardened binder is passed, on a conveyor device, for the shaping of the product and for the hardening of the binder, into a curing oven (2) designed in the manner of a tunnel oven, and having an upper belt (21) and a lower belt (22). According to the invention, between the raw unbonded web (3) and the upper belt (21) and/or the lower belt (22) here there is a permeable separator belt (5) arranged. The invention further relates to a corresponding apparatus (1) and to a mineral wool product produced therewith. The result is an improved method of production of a mineral wool product, where in particular the cost of downstream operations on the mineral wool products discharged from the curing oven can be reduced.

Description

description

Process and apparatus for producing a mineral wool product and mineral wool product made therewith

The invention relates to processes for the production of a mineral wool product, in which a raw nonwoven provided with an uncured binder mineral wool on a conveyor for molding the product and for curing of the

Binder is passed into a curing oven, which is designed in the manner of a tunnel oven and has an upper belt and a lower belt. The invention further relates to a device according to the preamble of claim 9 and the use of this device according to claims 17 and 18 and a mineral wool product according to claim 19.

In the production of mineral wool products, a raw fleece is first produced. This contains mineral wool fibers, which are produced in a defibration station, then wetted with an uncured binder and then deposited on a conveyor. The raw nonwoven fabric thus formed is typically carried away by the conveyor continuously from the area of the fiberizing station and is generally subjected to finishing steps such as, for example, thickness compression, longitudinal upsetting or the like. Finally, this raw nonwoven is passed into a curing oven, in which the binder usually cures by heat and / or radiation and thus results in a product with a predetermined geometry, which is still available as a continuous web. From this, depending on the type of product desired, usually plate-shaped mineral wool products for thermal or acoustic insulation are usually produced by vertical and / or horizontal cuts. The hardening of the binder in the hardening furnace is a significant process step for the product properties. Since the nonwoven web is continuously passed through the hardening furnace, the process conditions in the hardening furnace must be precisely controlled in order to ensure complete curing of the binder for establishing the integral cohesion within the hardening furnace To achieve mineral wool fleece, without bringing too much energy into the mineral wool fleece, which could lead to damage to the structure and would also be associated with a waste of energy. In practice hardening furnace with an upper belt and a lower belt are often used for the hardening step, between which the raw fleece is present and by means of which the raw fleece is moved through the hardening furnace. Such hardening furnaces are also referred to as tunnel ovens.

In order to achieve a uniform curing of the binder over the entire thickness of the raw nonwoven, one usually makes use of the open-pore structure of the mineral wool to achieve a throughflow drying. For example, in the region of the upper belt, a heated hardening gas such as e.g. Provided air with overpressure, wherein on the lower belt, a negative pressure is applied in such a way that the hardening gas, starting from the upper belt flows through the raw fleece and finally the lower belt and is sucked out there. This process can also be carried out in the opposite direction. A tunnel kiln can also be subdivided in sections into several curing areas, as a result of which different temperature zones can be set. The flow ensures that not only the binder in the near-surface areas of the raw nonwoven cures, but a complete through hardening of the web succeeds.

However, for the hardening gas to be effective, it must not only penetrate the mineral wool but also be able to pass through corresponding openings in the upper belt and in the lower belt. In other words, the upper and the lower band must have a sufficient perforation, so that the desired Durchströmungsmaß and thus achieves a practical curing speed become. This procedure for curing a binder in a mineral wool fleece has proven very successful in practice.

However, since the raw fleece is passed through the curing oven in a compressed state, so that a constant target thickness of the product to be produced is achieved, it is unavoidable in the conventional procedure that a mineral wool material present in the region of the openings in the upper or in the lower band of the curing oven certain dimensions enters these openings and is visible on the cured product as so-called flight prints. These flight prints are regular elevations on the large surfaces of the cured mineral wool fleece.

Since mineral wool products are often installed concealed as for example in an intermediate rafter insulation or the like, these Flightabdrücke in practice usually not a problem. It is different, however, if the product surface of the mineral wool product to be produced is still visible in the installed state or increased demands be set to the planicity of the surface .. This is the case, for example, certain facade insulation panels and acoustic or Schalldämmplatten. In particular, in the case of soundproofing panels, such flightprints are regarded as unacceptable, since they are usually used on the ceiling in the interior and thus would be permanently visible. Often, such acoustic or sound insulation panels are also provided for reasons of appearance with high quality and correspondingly expensive laminations, with a show through the Flightabdrücke by the applied lamination is to be avoided in any case.

Therefore, the visible surface of such sound insulation panels is regularly reworked. This is typically done by a multi-stage grinding, with which on the one hand removes the elevations in the form of the flight prints and on the other hand, an exact planicity of these plates is made. However, this post-processing step is expensive. It requires considerable mechanical as well as personnel and time and is therefore costly. In addition, such mineral wool panels are currently typically made with an oversize in thickness to provide enough material for the grinding operation. In the conventional way of production thus an additional use of material is given mineral wool material, wherein the excess mineral wool material is destroyed by the grinding step and finally eliminated. This also creates additional costs both with regard to the provision of the additional amount of mineral wool for the oversize and for the disposal of the abraded material.

The invention is therefore based on the object to further develop a method and apparatus for producing a mineral wool product of the generic type such that the Nachbearbeitungsaufwand can be reduced to the resulting from the curing oven mineral wool products.

This task is procedurally characterized by the characteristics of

Claim 1 solved. This is characterized in particular by the fact that between the raw fleece and the upper belt and / or the lower belt, a diffusion-open release belt is arranged.

The invention is thus based on the finding that it is possible despite the non sticky by the uncured binder surface of the nonwoven fabric and the required maintenance of Durchströmungsfähigkeit of Rohvlieses by the hardening medium, a separating element between the surface of the nonwoven fabric and the upper belt and / or To arrange sub-band and so prevent the penetration of mineral wool sections in the flow openings therein.

It has been shown in practical experiments within the scope of the invention that, when using a suitable release tape, adhesion of the raw nonwoven to this during the curing of the binder can be substantially avoided. The release tape is therefore not an integral part of the produced mineral wool product and can be removed after the hardening step, without it to damage to the near-surface mineral wool material in the product. At the same time, the separating belt bridges the openings in the upper belt or in the lower belt in such a way that an escape of mineral wool material into these openings is prevented and thus no increases in the product result. Therefore, according to the invention, a particularly flat product surface patterned without a flightprint is achieved.

Depending on the optical requirements, the mineral wool products produced by the method according to the invention can thus be used on the visible surface without a post-processing step, so that in particular the costly grinding step on the product surface can be dispensed with. As a result, the production cost of such mineral wool products reduced significantly, which speeds up production, reduces the equipment as well as human resources and thus significantly reduces costs. Moreover, according to the invention, there is no longer an excess in terms of the ultimately desired product thickness, which reduces the cost of materials. For high-quality acoustic or sound insulation panels with special requirements on the visual impression is i. d. R. the grinding step still required, but the advantages listed can be at least partially realized. In particular, the method according to the invention makes it possible to reduce the hitherto often multi-stage to a single-stage grinding step.

Furthermore, the separating tape according to the invention is designed to be open to diffusion, so that it allows a reliable flow through the hardening medium and thus does not significantly hinder the hardening step. The inventive method thus continues to achieve a reliable through hardening of the mineral wool product to be produced.

Another advantage is that the method according to the invention can easily be adapted to these variants by a slight modification of conventional production lines. is feasible. The cost of retrofitting conventional production equipment is therefore low.

Advantageous developments of the method according to the invention are the subject of the dependent claims 2 to 8.

Thus, the separating belt can be fed to a large surface of the raw non-woven in the conveying direction before the curing oven and led away in the conveying direction after the curing oven from the cured web. This can be achieved with simple means a provision as well as a removal of the separating tape directly in the desired work area. In particular, this can be retrofitted with little effort a conventional production line.

In this case, it is possible for the separating belt to be pulled off a ready position roller in front of the hardening furnace and rolled up onto a collecting roller after the hardening furnace. In this way, the separating tape can be applied in the manner of a conventional lamination with simple means on the upper or lower surface of the raw nonwoven and then lift off again with little effort. This procedure has the advantage that it can be carried out with very little effort on conventional lending lines and does not adversely affect further production steps. At the same time, the separating belt can be easily disposed of after a single use or as far as possible after a desired number of applications, without the continuous manufacturing process would be affected thereby.

Alternatively, however, it is also possible for the separating belt to be provided as an endless belt, which is cleaned off, for example, continuously by binder residues etc. adhering thereto. Even such an endless belt can be excellently integrated into the continuous production process in the production of mineral wool products. An adaptation of conventional processes is possible with little effort. According to an alternative procedure, it is also possible for a separating band to cover the upper band and / or the lower band and to circulate with it. This has the advantage that changes to the production plants arise only within the curing oven and here in the range of the upper band and the lower band. The separating belt can be arranged, for example, in the manner of the stocking over the upper belt or the lower belt and can be continuously cleaned by suitable means. The space required for this procedure is particularly low.

In this case, the separating tape can be formed as a glass filament fabric, for which the terms glass fiber fabric or glass fabric are used, which has proven in practical experiments to be particularly suitable for this purpose. Glass filament fabric has good structural integrity, although it has only a very small thickness, so that a very vapor-permeable release tape can be achieved. The flow resistance in the curing oven is therefore only slightly influenced by such a glass filament fabric. In addition, such a glass filament fabric has an open-pore shape with irregular, relatively small pores, so that there are no flow openings of the size that mineral wool material from the raw fleece would enter into this relevant extent. Moreover, such glass filament fabrics have a sufficient intrinsic stability that they can reliably bridge the flow openings in the upper band or in the lower band against the compression pressure within the curing oven and thus reliably counteract the formation of elevations on the product surface of the mineral wool fleece. Furthermore, this inherent stability allows a reliable lifting of the release tape from the cured web without damaging the nonwoven structure of both the glass filament and the cured web.

Alternatively, it is also possible that the separating tape made of polytetrafluoroethylene

(PTFE) is formed and perforated. This plastic is characterized by excellent material properties, in particular with regard to its heat resistance and its adhesion protection. Like practical experiments within the scope of the invention have shown hardened binder does not adhere to a relevant extent on a release tape made of PTFE, so that it comes when lifting from the product surface to no destruction of these in the process flow. At the same time, PTFE can be provided in very thin layers and with suitable perforations, so that the flow resistance with respect to the flow through the raw nonwoven by the hardening medium hardly develops relevance. Furthermore, such a film-like separating belt further has a very good mechanical strength. The given inherent stability of such a release tape made of PTFE also allows a reliable bridging of the flow openings in the upper belt and / or in the lower belt of the curing oven, so that thereby an entry of mineral wool material is reliably prevented in these openings. The formation of Flightabdrücke can thus be reliably avoided by a separating belt made of PTFE.

In a further alternative, it is also possible to form the separating belt as a metal mesh, in particular as a stainless steel mesh, which is particularly advantageous in terms of robustness and longevity of the separating strip.

According to a further aspect of the invention there is provided according to claim 9, an apparatus for producing a mineral wool product comprising a conveyor for directing a raw web of uncured binder mineral wool to form the product and cure the binder into a hardening furnace, which is of the type known in the art Tunnel furnace is formed and has a top band and a lower band. The device according to the invention is distinguished by the fact that a diffusion-open separating belt is arranged between the raw fleece and the upper belt and / or the lower belt.

By means of the device according to the invention, the above-mentioned advantages can likewise be achieved. In addition, such a device can be realized in an advantageous manner with little effort and retrofitted in existing production lines. Advantageous developments of the device according to the invention are the subject matter of the dependent claims 10 to 16. With these features, the advantages explained above with reference to the method can be achieved analogously within the scope of the invention.

According to yet another aspect of the invention according to claim 17, the use of a erfϊndungsgemäßen device for the production of sound insulation panels specified. The device according to the invention can be used particularly advantageously in the production of sound insulation panels, since these typically have a relatively large density in order to support the soundproofing effect. Accordingly, the degree of compression of the raw nonwoven fabric in the curing oven is comparatively high and thus in conventional devices the degree of mineral wool entry into the throughflow openings in the upper band or in the lower band is particularly pronounced. By virtue of the measures according to the invention, namely the provision of a diffusion-open separating belt between the raw nonwoven and the upper belt or the lower belt of the hardening furnace, however, the formation of such flighting pressures can also be particularly reliably prevented even in the production of soundproofing plates.

According to yet another aspect of the invention according to claim 18 is the

Use of a device according to the invention for the production of facade insulation panels specified. Again, it has proved to be particularly advantageous if the flight prints are avoided on the visible surfaces by the inventive measures.

According to claim 19, the invention further provides a mineral wool product, in particular a sound insulation panel or facade insulation panel, from bonded mineral wool, which is preferably produced by a method according to the invention or a device according to the invention. This mineral wool product is characterized in that at least one large area thereof is flat and has no elevations, which are formed by openings in the upper band and / or in the lower band of a curing oven.

The invention will be explained in more detail in exemplary embodiments with reference to the figures of the drawing. It shows:

Fig. 1 is a schematic side view of a device according to the invention in a first embodiment;

FIG. 2 shows a schematic side view of a device according to the invention in a second embodiment; FIG.

Fig. 3 is a schematic side view of a device according to the invention in a third embodiment;

Fig. 4 is a section through a conventional mineral wool product; and

5 shows a section through a mineral wool product produced according to the invention.

According to the illustrations in the figures, a device 1 comprises a hardening furnace 2, in which a raw fleece 3 made of mineral wool, which is provided with an unhardened binder, is brought in and then subjected to a hardening. Subsequently, it leaves the hardening furnace 2 as a shaped mineral wool fleece 4. In the hardening furnace 2, two counter-rotating conveyor belts are arranged, which receive the raw fleece 3 between them and pass through the hardening furnace 2. This task is fulfilled by an upper belt 21 and a lower belt 22. These are provided in a conventional manner with flow openings for a hardening medium, which is typically heated and sucked by a suction device, not shown here in the region of the lower belt 22 from the region of the upper belt 21 ago and thus passed through the raw fabric 3 therethrough. The binder hardens in the raw nonwoven 3. The resulting mineral wool nonwoven 4 can then by suitable Post-processing steps such as cuts etc. are processed to specific mineral wool products. For example, sound or facade insulation panels can be manufactured as a result.

The devices 1 according to the representations in FIGS. 1, 2 and 3 differ in the manner of arrangement and the design of a separating strip which is arranged and guided between the upper side of the non-woven fabric 3 and the upper belt 21 in the region of the hardening furnace 2.

As shown in FIG. 1, a separating belt 5 is provided, which is drawn off from a supply roller 6 arranged in the conveying direction in front of the hardening furnace 2 and introduced into the region between the raw fleece 3 and the upper belt 21. At the rear end of the curing oven 2 in the direction of conveyance, the separating belt 5 is lifted off from the now formed mineral wool nonwoven 4, wherein the separating belt 5 is rolled up onto a collecting roller 7. As soon as the separating belt 5 has been completely removed from the supply roller 6, it is either replaced by the collecting roller 7 or another supply roller with a separating belt 5 which has not yet been used or which has already been used.

2, an alternative embodiment of a device 1 is shown, according to which a separating belt 5 'is formed as an endless belt and is guided around by deflecting rollers 8 around the upper portion of the curing oven 2, that within the curing oven 2 between the surface of the green fabric. 3 and the upper belt 21 of the curing oven 2 comes to rest.

In the further embodiment according to Fig. 3, a separating belt 5 "completely covers the upper belt 21 of the hardening furnace 2 and circulates therewith, while the separating belt 5" is stretched over the upper belt 21 like a stocking.

In all embodiments cleaning devices, not shown here, are provided in the figures, which binders remain on the separating belt 5, 5 'or 5 "

il Separate medium or fiber particles from this. This is particularly advantageous in the case of the endlessly designed separating strips 5 'and 5 "according to FIGS 2 and 3, with particular regard to the continuous use of the separating strips so as to be able to keep the replacement intervals of the same large. 1, the cleaning is of particular advantage with regard to multiple use of the separating tape 5.

In Figs. 4 and 5, a conventional mineral wool product 9 and a mineral wool product 9 'produced according to the invention are compared with each other.

FIG. 4 shows a cross section through the conventional mineral wool product 9, on which significant elevations 91 are visible on the sides of both large areas, which are also referred to as flight prints. These increases have arisen because mineral wool material has entered the perforation openings in the upper and lower band of the curing oven from the large areas due to the compression pressure in the hardening furnace.

5, on the other hand, shows the mineral wool product 9 'produced by a device 1 according to one of the FIGS. 1 to 3, in which there are no elevations 91 on the upper side, since the separating strip 5 or 5' or 5 "was arranged there On the underside, to which no separating belt was used in the illustrated embodiments, there are also elevations 91. The flat upper side of the mineral wool product 9 'can thus serve as a visually appealing visible surface.

The release tape is e.g. a glass filament fabric in the manner of one with

PTFE coated glass mesh fabric tape used. This has an open mesh size of about 1 mm * 1 mm and has a thickness of about 0.65 mm. It is an endless belt with air-permeable spiral connection and Kevlar edges on both sides. An example of this is a glass filament fabric with warp and weft made of E glass according to material class DIN 5159/1 and a basis weight between 100 g / m ² and 500 g / m ² . The thread density on warp is in the range of 12 to 19 threads / cm and the weft at about 11 to 12 threads / cm. The threads are non-slip and contain no fibers with a diameter smaller than 3 microns. The loss on ignition is 5 to 6%, with the tensile strength on the chain in the range of 850 to 3500 N / 50mm and at the weft between 1500 and 2000 N / 50mm. The elongation at break is less than 4.0% on warp and weft.

The following are examples of such glass filament fabrics:

Example 1 :

Glass filament fabric, black, flame retardant, uniform structure Yarn according to DIN EN 12654: Chain: EC 9-34 / tex Weft: EC 9-68 / tex

Thread density according to DIN EN 1049: Chain: 12.0 threads / cm

Shot: 11.5 threads / cm basis weight according to DIN EN 12127: finished goods: 127 g / m ²

Raw material: 120 g / m ² loss on ignition according to DIN ISO 1887: <6%

Tensile strength according to DIN EN 12654: Chain:> 850 N / 50mm

Shot:> 1700 N / 50mm Elongation at break according to DIN EN 12654: Chain <3.5%

Shot <4.0%.

Example 2:

Glass filament fabric, white, flame retardant, uniform structure Yarn according to DIN 60 850/1: Chain: EC 9-68 / tex

Weft: EC 9-68 / tex Yarn density according to DIN 53 853: Warp: 12.0 threads / cm

Shot: 11.5 threads / cm Basis weight according to DIN 53 854: finished product: 172 g / m ²

Raw material: 163 g / m ²

Loss on ignition according to DIN ISO 1887: <6% Tear strength according to DIN 53 857: Chain:> 1700 N / 50mm Weft:> 1700 N / 50mm

Elongation at break according to DIN 53 857: chain <4.0%

Shot <4.0%.

Example 3: Glass filament fabric, white, non-combustible according to IMO Resolution A.472 (XII), uniform structure Yarn according to DIN 60 850/1: Chain: EC 9-136 / tex

Shot: EC 9-136 / tex

Thread density according to DIN 53 853: Chain: 19.0 threads / cm Weft: 11.0 threads / cm

Basis weight according to DIN 53 854: finished product: 430 g / m ²

Raw material: 420 g / m ² loss on ignition according to DIN ISO 1887: <5%

Tensile strength according to DIN 53 857: Chain:> 3500 N / 50mm Weft:> 2000 N / 50mm

Elongation at break according to DIN 53 857: chain <4.0%

Shot <4.0%.

Example 4: Glass filament fabric, white, Low Flame Spread Surface material according to IMO Resolution A.653 (16), IMO Resolution MSC 61 (67), uniform structure Yarn according to DIN 60 850/1: Chain: EC 9-68 / tex

Shot: EC 9-68 / tex

Thread density according to DIN 53 853: Chain: 17 threads / cm Weft: 12 threads / cm

Basis weight according to DIN 53 854: finished product: 220 g / m ² Raw material: 204 g / m ²

Ignition loss according to DIN ISO 1887: <6% Tear strength according to DIN 53 857: Chain:> 2200 N / 50mm

Shot:> 1500 N / 50mm.

The glass filament fabric used can be made especially for this purpose or come from defective batches from the production of such glass filament fabric.

The invention allows, in addition to the illustrative embodiments, further design approaches.

For example, it is also possible to provide a corresponding separating tape in the region between the raw fleece 3 and the lower belt 22 so as to avoid the formation of flight prints on the underside of the mineral wool fleece. In particular, this can also be used to achieve products which do not have any flightprints on both sides, in that a separating band 5 or 5 'or 5 "is carried along in the hardening furnace both on the underside and on the upper side of the raw nonwoven 3.

As a release tape can also be an uncoated or otherwise coated

Glass filament fabric, a plastic tape e.g. made of PTFE or a stainless steel mesh with a mesh width of approx. 0.5 mm.

Claims

claims

1. A process for producing a mineral wool product, wherein a raw fleece (3) 5 provided with an uncured binder mineral wool on a

Conveying device for shaping the product and curing the binder in a hardening furnace (2) is passed, which is designed in the manner of a tunnel furnace and an upper belt (21) and a lower belt (22),

o characterized

in that a diffusion-open separating belt (5, 5 ', 5 ") is arranged between the raw fleece (3) and the upper belt (21) and / or the lower belt (22) (5; 5 '; 5 ") of a large surface of the raw nonwoven fabric (3) fed in the conveying direction before the curing oven (2) and in conveying direction after the curing oven (2) from the cured web (4) is led away. 0

3. The method according to claim 2, characterized in that the separating belt (5) in front of the curing oven (2) withdrawn from a supply roll (6) and after the curing oven (2) is rolled onto a collecting roller (7).

4. The method according to claim 2, characterized in that the separating belt (5 ', 5 ") 5 is provided as an endless belt.

5. The method according to claim 1, characterized in that the separating belt (5 ") covers the upper belt (21) and / or the lower belt (22) and rotates with it

6. The method according to any one of claims 1 to 5, characterized in that the separating strip (5; 5 '; 5 ") is formed as a glass filament fabric.

7. The method according to any one of claims 1 to 5, characterized in that the separating strip (5; 5 '; 5 ") is formed of PTFE and perforated.

8. The method according to any one of claims 1 to 5, characterized in that the separating belt (5, 5 ', 5 ") as a metal fabric, in particular as a stainless steel fabric is formed.

9. Device (1) for producing a mineral wool product, with a conveying device for guiding a raw nonwoven fabric (3) with an uncured one

Binder provided mineral wool for molding the product and for curing of the binder in a hardening furnace (2), which is designed in the manner of a tunnel furnace and has an upper belt (21) and a lower belt (22),

characterized,

a diffusion-open separating belt (5, 5 ', 5 ") is arranged between the raw fleece (3) and the upper belt (21) and / or the lower belt (22).

10. Apparatus according to claim 9, characterized by a feed device for feeding the separating belt (5, 5 ') to a large surface of the raw nonwoven fabric (3) in the conveying direction before the curing oven (2), and by a removal device for carrying away the separating belt (5; ') from the cured web (4) in the conveying direction after the curing oven (2).

11. The device according to claim 10, characterized in that the supply device is a supply roller (6) and that the removal device is a collecting roller (7).

12. The device according to claim 10, characterized in that the separating belt (5 ', 5 ") is formed as an endless belt.

13. The apparatus according to claim 9, characterized in that the separating belt (5 ") covers the upper belt (21) and / or the lower belt (22) and rotates with this.

14. Device according to one of claims 9 to 13, characterized in that the separating strip (5, 5 ', 5 ") is formed as glass filament fabric.

15. Device according to one of claims 9 to 13, characterized in that the separating belt (5, 5 ', 5 ") is formed and perforated from PTFE.

16. Device according to one of claims 9 to 13, characterized in that the separating belt (5, 5 ', 5 ") as a metal fabric, in particular as a stainless steel mesh, is formed.

17. Use of a device (1) according to any one of claims 9 to 16 for the production of sound insulation panels.

18. Use of a device (1) according to any one of claims 9 to 16 for the production of facade insulation panels.

19. mineral wool product (9 '), in particular sound insulation board or Fassadendämm- plate, made of bonded mineral wool, preferably prepared by a method according to one of claims 1 to 8 or by a device (1) according to one of

Claims 9 to 16, characterized in that at least one large surface of the mineral wool product (9 ') is flat and has no openings (91) formed by openings in the upper belt (21) and / or in the lower belt (22) of a hardening furnace (2).