3D non-woven fiber web production facility

Abstract

The invention relates to an installation for producing a 3D fabric from nonwoven fibers, particularly felt, comprising a device (8) for depositing a mixture of substantially unbonded fibers, in the form of a base layer (5), onto an air-permeable, particularly perforated, conveyor belt. The base layer is conveyed to a zone (2), called the supply zone, which is arranged in front of at least one nozzle (3) for supplying additional fibers. The fiber supply nozzle deposits additional fibers onto the base layer to form, in at least one region thereof, at least one additional layer (6) in order to obtain a three-dimensional or 3D preformed layer with a thickness and / or mass per unit area that can vary spatially. The 3D preformed layer is subsequently conveyed to a consolidation element (7) to consolidate it into the finished 3D fabric, the thickness and / or mass per unit area of ​​which can also vary spatially.The installation is characterized in that suction means are provided arranged so as to suction the air contained in the base layer to keep said base layer on the conveyor belt in the supply zone, and at least one nozzle (3) is an injection nozzle that supplies the additional fibers by spraying or injection through an air stream.

Description

[0001] The present invention relates to a production installation for producing non-woven fiber mats, in particular felt, shaped in three dimensions (3D) and / or having a variable surface mass in space, particularly intended for use in the automotive industry.

[0002] Three-dimensional non-woven fiber mats of variable thickness and / or surface mass in space are of great interest, particularly for manufacturing products in a wide range, especially in the automotive industry for sound and / or thermal insulation of doors, pavilions, ceilings, floors, interior coverings and the like.

[0003] Preformed nonwoven fiber products of varying thickness and / or surface mass are typically produced from layers of fibers, lacking true cohesion between them. These layers are formed from a mixture of fibers containing binding fibers or particles. They are molded, then removed from the mold and heated in an oven to pre-consolidate them, resulting in a nonwoven fiber element that conforms to the mold's shape. The binding fibers or particles are "activated" during heating. The resulting products have the mold's shape and sufficient cohesion to be handled and transported to further molding stages of the final parts, incorporating additional layers of nonwovens, textiles, and other sound-absorbing materials.

[0004] These molding systems are particularly complex to build and operate. Demolding the unconsolidated fibers and handling the molds is delicate until consolidation occurs in the furnace. Furthermore, rotary mold systems, such as the one described in EP2532777A1, have the additional disadvantage of being poorly suited to the production of large parts.

[0005] It is also known, for example from WO2009 / 043195A1, to produce 3D nonwoven fiber mats using multiple nozzles covering the entire width of the part to be produced, each nozzle delivering fibers onto a conveyor belt with suction from below. While the parts obtained with this technique can be quite large, they do not exhibit good resistance to stress.

[0006] We also know of US2017 / 0369005A1, an installation for forming a muffler for automobiles by compression molding, in which a main hopper deposits by gravity a layer of base fibers onto a conveyor belt and secondary hoppers deposit additional fibers on the layer of base fibers to form additional layers to obtain a preformed 3D layer of variable thickness and / or surface mass in space, the preformed layer being then conveyed, after a possible preheating operation, into a compression molding installation producing the muffler.

[0007] We would like to have a production facility for fiber-based products of this kind that is much simpler to implement and that allows us to obtain a product with better resistance.

[0008] According to a first aspect of the invention, an installation for manufacturing a non-woven fiber mat, particularly felt, in 3D, comprising a device for depositing a mixture of substantially unbonded fibers in the form of a base layer onto an air-permeable conveyor belt, particularly perforated, the base layer being conveyed to a so-called supply zone arranged opposite at least one additional fiber supply nozzle, the at least one fiber supply nozzle depositing additional fibers onto the base layer to form, in at least one region of the base layer, at least one additional layer to thus obtain a preformed three-dimensional or 3D layer having a thickness and / or surface mass that varies in space,The preformed 3D layer is then conveyed into a consolidation element to consolidate the preformed 3D layer into the final 3D sheet having a thickness and / or surface mass that varies in space, characterized in that suction means are provided, arranged so as to draw the air contained in the base layer to maintain it on the conveyor belt at the level of the supply zone, and at least one nozzle supplies the additional fibers by projection or injection by an air stream.

[0009] By planning to deposit on a pre-formed base fiber layer the studs and other shapes having a volume intended to give the fiber layer the shape of a 3D product, in order to obtain, after consolidation of the fibers of the layer, a final product based on a 3D fiber sheet, in particular felt, having a variable thickness and / or surface mass in space, the inventors realized, to their great surprise, that the additional parts added to the layer moving in front of the feed nozzles held their shapes at least until their consolidation in the oven, which made it easy to obtain the 3D products, in particular without having to use a complicated molding installation.In addition, the product obtained is very homogeneous, has great stability and resists stress well, unlike parts of prior art systems which have interfaces in their material extending throughout the length and height which impair their resistance.

[0010] Preferably, according to a second aspect of the invention, which in itself constitutes an invention independent of the first aspect of the invention, but which can be favorably implemented with it, an installation for manufacturing a 3D non-woven fiber mat, in particular felt, comprising a device for depositing a mixture of substantially unbonded fibers in the form of a base layer onto an air-permeable conveyor belt, in particular perforated, the base layer being conveyed to a so-called supply zone disposed opposite at least one additional fiber supply nozzle, the at least one fiber supply nozzle depositing additional fibers onto the base layer to form at least one additional layer in at least one region of the base layer, thus obtaining a preformed three-dimensional or 3D layer having a thickness and / or surface mass that varies in space,The 3D preformed layer is then conveyed into a consolidation element to consolidate the 3D preformed layer into the final 3D sheet having a variable thickness and / or surface mass in space. This system is characterized in that it provides means for controlling the speed of the conveyor belt. These control means include means for stopping or slowing down the movement of the belt for a given period of time, the time needed to deposit one or more additional layers on the base layer for the formation of a given 3D preformed layer for the formation of a product, before restarting or accelerating the belt to move the 3D preformed layer a given distance, thus allowing the deposit of one or more additional layers for the formation of a subsequent product on the base layer.

[0011] According to the invention, favorably, only one additional fiber supply nozzle can be provided in the preformed layer formation zone.

[0012] In particular, according to a third aspect of the invention, which in itself constitutes an invention independent of the other aspects of the invention, but which can be implemented favorably with each of them or with both together, an installation for manufacturing a non-woven fiber mat, in particular felt, in 3D, comprising a device for depositing a mixture of substantially unbonded fibers in the form of a base layer onto an air-permeable conveyor belt, in particular perforated, the base layer being conveyed to a so-called supply zone disposed opposite at least one additional fiber supply nozzle, the at least one fiber supply nozzle depositing additional fibers onto the base layer to form in at least one region of the base layer at least one additional layer to thus obtain a preformed three-dimensional or 3D layer having a thickness and / or surface mass that varies in space,The preformed 3D layer is then conveyed into a consolidation element to consolidate the preformed 3D layer into the final 3D sheet having a variable thickness and / or surface mass in space. This is characterized in that means are provided to control the movement of the additional fiber supply nozzle above the supply zone, in order to control the movement of the nozzle above the supply zone according to the desired final shape of the product.

[0013] However, instead of moving a single nozzle over the delivery area, one could also use a plurality of nozzles, which are fixed and / or also mobile, to bring the additional fibers onto the base fiber layer.

[0014] Preferably, at least one nozzle is attached to at least one control arm, in particular controlled by a robotic system.

[0015] Preferably, the consolidation element is a heat treatment element, in particular a furnace.

[0016] Once the product has come out of the oven, the final sheet obtained by thermal consolidation can either be rolled up, or the products can be cut one after the other into predetermined size formats and, if necessary, stacked.

[0017] Preferably, the base layer is continuous.

[0018] Preferably, at least one template is provided, in particular attached to a control arm, in particular controlled by a robotic system, intended to be positioned so as to delimit the shape of a region into which additional fibers are brought.

[0019] Preferably, the fiber mixture comprises non-binding fibers and binding fibers or particles, the latter being intended, under the effect of the final heat treatment, to consolidate the preformed layer to obtain the 3D sheet.

[0020] Preferably, the base layer has a base thickness and / or surface mass and the 3D preformed layer has a greater thickness and / or surface mass between 1.1 times and 5 times the thickness / surface mass of the base layer, in particular between 1.2 and 3.

[0021] Preferably, the conveyor belt has a straight section, particularly at the feed zone.

[0022] According to an improvement, which in itself constitutes an invention independently of the above-described aspects of the invention, but which can be favorably combined with each of them or a combination of two or more of them, the 3D sheet entering a furnace is sandwiched between two upper and lower belts respectively during thermal consolidation, the two belts being at a distance from each other, which makes it possible to obtain a sheet at the exit of regular thickness, thickness which corresponds to the distance between the two lower and upper belts of the furnace, which makes it possible for the pre-consolidated or consolidated sheet at the exit of the furnace to have a substantially constant thickness and a variable basis weight or density.

[0023] Thus the present invention also relates to an installation for manufacturing a non-woven fiber mat, in particular felt, in 3D, characterized in that it comprises a thermal consolidation oven in which the 3D mat is sandwiched between two mats respectively upper and lower, at a distance from each other.

[0024] By way of example, an embodiment of an installation according to the invention is described, with reference to the drawings in which: There figure 1 is a side view of an installation according to the invention; and The figure 2 is a side view of the end of the installation of the figure 1 including the oven and a reel.

[0025] To the figure 1A fiber blending device 8 deposits fibers onto a first perforated, endless straight conveyor 9. The fibers consist of a blend comprising base fibers, for example polyester fibers or natural fibers from a pneumatic webbing machine, and binder fibers, for example polypropylene, copolyester, or a polyester-copolyester bicomponent, to form a continuous layer 5 of fibers. This layer 5 is then transferred onto a second perforated, endless straight conveyor 1. In another embodiment, the two conveyors 9 and 1 could be replaced by a single conveyor performing all the conveying functions of the two separate conveyors.

[0026] In this layer 5 of fibers, the fibers do not have cohesion with each other, and for example, fibers can be removed by hand without the rest of the layer following.

[0027] The layer of fibers thus formed and transferred onto the perforated belt 1 then passes into a supply zone 2, opposite which a nozzle 3 for supplying additional fibers can move, under the control of a robot arm controlled by an appropriate electronic control circuit well known in the field, and which allows, depending on the speed of movement of the arm, the speed of exit of the fibers from the nozzle, the diameter of the nozzle, the distance of the nozzle to the layer, the weight of the fibers added, etc., to deposit additional layers 6 of fibers in certain places of the base layer to obtain; at the exit of the supply zone, a preformed layer whose shape is a function of the 3D shape of the final product that one intends to obtain.

[0028] The supply nozzle 3 is here an injection nozzle, which injects the additional fibers via an injection air stream.

[0029] To ensure that nozzle 3 has time to inject all the necessary fibers to create the volumetric parts corresponding to the desired 3D product shape, the control means for moving the conveyor belt supporting the base layer held by conventionally made retaining means are stopped for a sufficient period of time to allow the nozzle to deposit all the fibers necessary for the desired shape.

[0030] The nozzle can be attached to a computer-controlled robot arm. Another solution is to use multiple fixed nozzles, whose flow rates are controlled according to the desired final 3D shape. A combination of these two solutions—that is, a combination of fixed and mobile nozzles—is also possible. Similarly, instead of a single mobile nozzle, several mobile nozzles can be used, controlled by one or more robot arms.

[0031] Once the volumetric parts are deposited onto the base layer in the supply zone, a preformed layer is obtained. This preformed layer is then conveyed into a furnace 7 for consolidation. This consolidation occurs through the melting of the binding fibers in the fiber mixture. Upon exiting the furnace, the web can be rolled or cut piece by piece, with each piece then stacked on top of the others.

[0032] In an advantageous embodiment, the 3D sheet entering the oven 7 is sandwiched between two upper and lower conveyors 71 and 72 during thermal consolidation. The two conveyors are spaced apart, resulting in a sheet of uniform thickness at the outlet, corresponding to the distance between the upper and lower conveyors of the oven. This ensures that the pre-consolidated or consolidated sheet exiting the oven has a substantially constant thickness and a variable basis weight or density. Upon exiting the oven 7, the thermally consolidated sheet is transferred to a winding device 9.

[0033] Preferably, the base layer has a surface weight of at least 300 g / m², in particular between 300 and 2,500 g / m².

[0034] Beneath the permeable mat, which is perforated with holes, a vacuum-forming device (4) is positioned to generate negative pressure towards the mat. This vacuum pressure ensures that the base layer remains firmly attached during the feeding and additional fiber delivery processes, and preferably also within the furnace.

[0035] The suction device is designed to apply negative pressure under the product in order to suction and hold the base layer and the preformed layer on the carpet during the various stages of the process.

[0036] The base material is preferably made of fibers, such as natural fibers, for example cotton fibers, and / or synthetic fibers, such as thermoplastic fibers and / or mineral fibers, or a combination thereof. In addition to fibers, the base material may contain other supplementary materials in the form of powders, granules, foams, or other substances. The base layer may have the same fibrous composition as the fibers deposited by the nozzle(s), or a different composition.

[0037] Part of the base material may include binding materials, such as binding fibers or particles in the form of powders, flakes or other, which are activated during heat treatment.

[0038] The fiber formation device, upstream of the device for depositing additional fibers via the nozzle(s), preferably comprises a pneumatic webbing machine. When the conveyor belt stops, the fiber feed to the webbing machine is stopped. The fiber feed to the webbing machine then resumes synchronously with the conveyor belt's advance so as to maintain a constant basis weight. It is also possible, in one embodiment of the invention, to vary the basis weight of the base layer in the direction of the layer's advance by varying the fiber feed to the webbing machine.

[0039] In one variation, the base layer could also be formed using a crosslapper preceded by a carding machine. In this case, the crosslapper and the carding machine that feeds it are synchronized with the line speed and stop. This crosslapper + carding machine solution also allows for the creation of base layers of varying basis weight before application by the nozzle(s). When the carding machine is driven by the crosslapper, it is possible to form a base layer of varying basis weight in a transverse direction, which is not possible with a pneumatic crosslapper.

Claims

1. Facility for producing a 3D fabric of non woven fibres, in particular made of felt, comprising a device (8) for depositing a mixture of fibres that are substantially not bonded together in the form of a base layer (5) on an air-permeable, in particular perforated, conveyor belt, the base layer being conveyed to what is known as a supply zone (2) located opposite at least one nozzle (3) for supplying additional fibres, the at least one fibre supply nozzle depositing additional fibres on the base layer to form at least one additional layer (6) in at least one region of the base layer to thus obtain a preformed layer in three dimensions or 3D layer having a thickness and / or a surface density that is variable in space, the preformed 3D layer then being conveyed into a consolidation element (7) to consolidate the preformed 3D layer into the final 3D layer having a thickness and / or a surface density that is variable in space, characterised in that aspiration means are provided, these being arranged such as to draw up the air contained in the base layer so as to maintain said layer on the conveyor belt in the region of the supply zone and the at least one nozzle (3) supplying the additional fibres by projection or injection by an air stream.

2. Facility according to claim 1, characterised in that means for controlling the speed of the conveyor belt are provided, and these control means comprise means for stopping or slowing down the movement of the belt over a given period of time, the time required to deposit one or more additional layers (6) on the base layer (5) to form a given preformed 3D layer in order to form a product, before starting up or speeding up the belt again to move the preformed 3D layer a given distance to thus allow one or more additional layers (6) to be deposited to form a subsequent product on the base layer (5).

3. Facility according to either claim 1 or claim 2, characterised in that only one nozzle (3) for supplying additional fibres is provided in the zone for forming the preformed layer.

4. Facility according to any of the preceding claims, characterised in that means for controlling the movement of the nozzle (3) or nozzles for supplying additional fibres are provided above the supply zone (2) for controlling movement of the nozzle (3) or nozzles above the supply zone (2) as a function of the desired final shape of the product.

5. Facility according to claim 4, characterised in that the at least one nozzle (3) is an integral part of at least one control arm, in particular driven by a robotic system.

6. Facility according to any of the preceding claims, characterised in that the base layer (5) is continuous.

7. Facility according to any of the preceding claims, characterised in that at least one template is provided, in particular as an integral part of a control arm, in particular driven by a robotic system, which is intended to be positioned such as to delimit the shape of a region in which additional fibres (6) are supplied.

8. Facility according to any of the preceding claims, characterised in that the consolidation element is an element for consolidation by heat treatment, in particular in an oven.

9. Facility according to any of the preceding claims, characterised in that the consolidation element by heat treatment is an oven.

10. Facility according to any of the preceding claims, characterised in that the mixture of fibres comprises non-binder fibres and binder fibres or particles, the latter being intended to consolidate the preformed layer under the influence of a final heat treatment in order to obtain the 3D fabric.

11. Facility according to any of the preceding claims, characterised in that the base layer (5) has a base thickness (or thicknesses) and / or surface density and the preformed 3D layer has a greater thickness (thicknesses) and / or surface density of between 1.1 and 5 times the base thickness / surface density, in particular between 1, 2 and 3 times.

12. Facility according to any of the preceding claims, characterised in that the conveyor belt has a straight section, particularly in the region of the supply zone (2).

13. Facility according to any of the preceding claims, characterised in that the 3D fabric entering an oven (7) is sandwiched between two belts, an upper (71) and lower (72) belt respectively during thermal consolidation, both belts (71, 72) being at a distance from one another.

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