EP1790766A1 - Method and device for transferring a fibre layer, and consolidation machine, in particular a (randomiser) needle loom thus equipped - Google Patents

Abstract

A method for transfer of a fibrous non-woven sheet (17) along the length of a transfer passage at an angle to the vertical involves contacting the underside (26) of the sheet with an underlying current of air, at least part of which has a component of motion in the transfer direction (27). Independent claims are included for: (1) a non-woven sheet transfer device, having a blower for introducing a current of air in contact with the underside (26) of the sheet (17), at least part of the current having a component of motion in the transfer direction (27); and (2) a non-woven sheet consolidation machine, having a sheet inlet equipped with the transfer device.

Description

The present invention relates to a method for transferring a sheet of fibers, in particular for introducing it into a consolidation machine such as a needling machine, more particularly a pre-needling machine.

The present invention also relates to a device for a web transfer.

The present invention also relates to a consolidation machine thus equipped, in particular a needling machine or, more particularly, a pre-needling machine.

Fiber webs are continuous textile products typically formed from layers of fibers. In each layer, the fibers are substantially parallel to each other in a direction oblique to the longitudinal direction of the web. The oblique direction of the fibers of a layer forms an angle with the oblique direction of the fibers of each adjacent layer. In general, these oblique directions make an angle of less than 90 ° with the longitudinal direction of the web.

Such a textile structure is particularly fragile because the fibers are not bonded to each other, neither inside a layer, nor from one layer to another. The sheet of fibers constitutes an intermediate product which must then pass through at least one consolidation machine connecting the fibers to one another, for example a needling machine whose function is to interlace the fibers and compact the sheet, to produce a consolidated sheet having excellent mechanical strength.

Before consolidation, the unconsolidated sheet is difficult to transfer along a production line, particularly in the interval between the conveyor and the conveyance area where the sheet is in contact with the means of advance of the machine consolidation. These means of advance can only have a pulling effect to advance the sheet. However, given the structure described above for the unconsolidated sheet, the unconsolidated sheet has virtually no tensile strength. It is also impossible to push the ply into the needling because the ply also has no mechanical compressive strength.

In a needling machine, when the needles are clear of the web, extractor rollers placed downstream of the needling path pull the web downstream so that the web performs a step forward. This traction, transmitted by the zone of the ply situated in the needling path, tends to undesirably and unevenly stretch the zone of the ply situated just upstream of the needling path.

To solve this problem, the US-A-5,031,289 discloses a conveyor belting system, lower and upper respectively, which pinch the web between them, compacting it in the direction of the thickness, to deliver it almost inside the consolidation machine. So that the device has as little space as possible in the direction of the thickness of the sheet, and can thus penetrate as far as possible in the consolidation machine, each conveyor belt bypasses, at the downstream end of the device, no not a rotating cylinder, but a kind of fixed spout whose profile has at its end bypassed by the carpet a radius of curvature chosen as low as possible for a reasonable longevity of the carpet.

The object of the present invention is to provide a method and a transfer device simpler and / or more effective for transferring a sheet of fibers, especially for its introduction into the first consolidation machine of a production line.

Another object of the present invention is to provide a consolidation machine, in particular a needling machine, and more particularly a pre-needling machine, thus equipped.

According to the invention, the method for transferring a sheet of fibers along a transfer path forming an angle with respect to the vertical, for example substantially horizontal, is characterized in that it is introduced in contact with the underside of the web an underlying airflow of which at least a portion has a movement component in the direction of transfer.

Thus, according to the invention, an underlying air flow is used which both alleviates or cancels the apparent weight of the sheet, reduces or cancels the friction against a mechanical support, and propels the sheet by friction of the air on the inner face of the web or respectively in the area of the lower layer of the web. It is advantageous to implement the process at the entrance of a needling machine. The air flow according to the invention brings the unconsolidated sheet to the needling path. The solution according to the invention is doubly surprising. On the one hand it turned out that a relatively moderate air flow was sufficient to obtain the expected transfer effect. On the other hand, the person skilled in the art was dissuaded from considering such a solution because usually, in the field of nonwovens, it seeks instead to shelter the textile web from any air flow, a priori likely to scatter the fibers of the tablecloth.

It is advantageous to introduce the stream as jets. In this way, an appropriate combination of the flow rate, the air velocity and the surface over which the airflow is distributed is obtained.

You can also jog the jets. This increases the speed for a given flow rate and causes the web shock or vibration that enhance the efficiency of the process.

The air jets may comprise substantially vertically directed lift air jets, which have the effect of lifting the web, and propulsion jets, oriented obliquely upwards and in the direction of transfer of the web. The propulsion jets have a propulsive effect, in addition to a certain lift effect. Preferably, the lift air jets act in the vicinity of the upstream end of the transfer zone according to the invention, and the propulsion air jets act further downstream.

It is advantageous to implement the method at the exit of a slatted conveyor, that is to say whose bearing surface intended to support the sheet is defined by a succession of slats which each extend transversely to the slat conveyor. transfer direction. These slats are typically carried by belts that rotate around guide rolls. The method according to the invention makes it possible, especially when the lift air jets are placed upstream, to lift the sheet before it approaches the turn of the slats around a return means, such as a cylinder, of the conveyor to slats. This prevents the lower part of the thickness of the sheet is stretched under the effect of laths which deviate from each other around the turn.

Preferably, a higher air flow is also directed on the upper face of the sheet, substantially opposite the underlying air flow, preferably by giving at least a portion of the upper air flow a movement component in the direction of transfer of the web.

Thus, there is a global action that tends to compress the web between the underlying air flow and the upper air flow, and is propelled by air flow friction on each of its two faces. However, it is preferable to give the underlying airflow greater power than the upper airflow in the vertical direction. Thus, the vertical resultant of the two air flows balances at least part of the weight of the web.

According to a second aspect of the invention, the web transfer device is characterized in that it comprises blowing means for introducing, in contact with the lower face of the web, an air flow of which at least a part has a motion component in the direction of transfer.

It is advantageous to provide means for differently adjusting at least one parameter, among pressure and flow, at different points along the length of the path of the web occupied by the device. These means may consist of different feed means for different areas of the length of the device, and / or independently adjustable feed means, and / or openings of different geometries or dimensions. There may also be more openings per unit area in some areas than in others.

It is advantageous for the device to define for the web an initially ascending and then substantially horizontal path. Thus, the initial lifting of the sheet by the lift flow, even if it is approximately vertical, can at the same time contribute to the propulsion of the sheet along the upward portion of the path.

It is advantageous that the orifices from which the air jets emerge, open into at least one recess of a surface. Preferably, at least one recess, relative to the direction of transfer, a steep upstream face and a gently sloped downstream face. The recesses are preferably grooves transverse to the direction of transfer. These recesses facilitate the drilling of the orifices during the manufacture of the device. In addition, they have a non-return effect on blow interruptions when the jets are pulsed at a rate related to the punching rate of the needling machine, the blow being interrupted when the needles are engaged in the sheet.

It is advantageous for the orifices to be staggered in order to best distribute the action of the air jets over the entire surface of the sheet concerned by the action of the device.

According to a third aspect of the invention, the consolidation machine, in particular a needling machine, in particular a pre-needling machine, is equipped with a device according to the second aspect.

Other features and advantages of the invention will emerge from the description below, relating to non-limiting examples.

• la figure 1 est une vue d'une pré-aiguilleteuse équipée d'un dispositif de transfert selon l'invention, en coupe dans un plan vertical parallèle à la direction longitudinale de la nappe ;
• la figure 2 est un agrandissement du dispositif de transfert de la figure 1, et de son environnement entre un convoyeur à lattes et la pré-aiguilleteuse ;
• la figure 3 est une vue schématique en perspective en coupe d'une partie du dispositif de transfert dans une variante de réalisation ;
• la figure 4 est une vue analogue à la figure 2, mais dans une deuxième variante de réalisation ;
• la figure 6 est une vue analogue à la figure 2, dans un deuxième mode de réalisation.

In the accompanying drawings:

• Figure 1 is a view of a pre-needling machine equipped with a transfer device according to the invention, in section in a vertical plane parallel to the longitudinal direction of the web;
• Figure 2 is an enlargement of the transfer device of Figure 1, and its environment between a slatted conveyor and the pre-needling machine;
• Figure 3 is a schematic perspective view in section of a portion of the transfer device in an alternative embodiment;
• Figure 4 is a view similar to Figure 2, but in a second embodiment;
• Figure 6 is a view similar to Figure 2, in a second embodiment.

In the example shown in FIG. 1, the pre-needling machine 1 constitutes the first machine for consolidating a textile web 17 (FIG. 2) exiting, for example, a crosslapper. A part of the exit apron is seen, constituted by a slatted conveyor 18 of the crosslapper. The conveyor 18 conveys the web 17 to the entrance 14 of the pre-acute groomer. The pre-needling machine 1 comprises a needling path 2 which extends in a substantially horizontal plane with a direction of transfer of the fibers which is in the plane of FIG. 1. The path 2 is defined on the lower side by a table of needling 3 and the upper side by a stripper 4, both perforated (not shown) for allow the passage of lower needles 5 and upper needles 6, respectively. Only some needles 5 and 6 are shown.

Below the needling table 3, the lower needles 5 are fixed to a needle board 7 itself attached to a beam 8, which is actuated vertically back and forth by a connecting rod-crank 9 which one only sees part of the connecting rod.

Similarly, above the stripper 4, the upper needles 6 are attached to an upper needle board 11, itself attached to a beam 12, operated vertically back and forth by a connecting rod-crank mechanism that is only partially represented.

The back and forth movement of the lower needles 5 and the upper needles 6 alternately penetrate the ends of the needles in the needling path 2 and respectively cause said ends of said path 2 to come out, to interlace the fibers of the ply (not represented) arriving by an introduction side 14 to come out in the form of a sheet at least partially consolidated on the extraction side 16. The direction of travel of the sheet along the path is defined by the arrow 27. The ends of the needles are provided with appropriate conformations to drive the fibers with them during the penetration stroke and / or during the withdrawal stroke.

More generally, a needling machine is called a needling machine in which the number, the distribution, the working stroke and the cadence of the needles, as well as the spacing and the angle of convergence between table 3 and stripper 4 are adapted to confer a first compacting and a first holding at an unbound consolidated web.

Figure 1 shows each needle board 7 or 11 in its maximum penetration position and, under the designations 7r and 11r, in its maximum retracted position. The two beams 8 and 12 are mainly represented in the maximum retracted position. In addition, in the maximum withdrawal position 7r and 11r, the left half of each board is shown in the loose state during assembly or disassembly operations.

The slatted conveyor 18 (FIG. 2) comprises, as an active element for conveying, transverse slats 19 fixed on at least one continuous belt 20. The belt 20 circulates around guide rolls and drive among which only a downstream return cylinder 21 preceding entry into the needling machine is shown.

FIG. 2 schematically shows that the upper surfaces of the slats deviate from each other when the slats pass from a rectilinear path preceding the cylinder 21 to a curved path around the cylinder 21.

A transfer device 22, according to the invention, is installed under the path of the web 17, between the slatted conveyor 18 and the inlet 14 in the needling 1.

The transfer device 22 comprises a transfer table 23 whose upper face 24 which faces the lower face 26 of the ply 17, is a fixed transfer surface, preferably coated with an anti-friction coating such as a polytetrafluoroethylene. Thus, the face 24 delimits the lower side of a transfer path 15 of the web 17. The path 15 is inserted between the conveying path 25, upstream, on the slat conveyor 18, and the path of needling 2 located downstream.

The transfer surface 24 has, from upstream to downstream relative to the direction of transfer 27 of the fibers, an ascending portion 24a of the transfer path and a substantially horizontal portion 24, which delimit corresponding portions, ascending and respectively horizontal, of the lower zone of the transfer path 15.

The table 23 extends at least over the entire width of the sheet.

Upstream, the upward portion 24a is connected, with a suitable operating clearance chosen as low as possible, to a region of the beginning of the descent of the slats 19 around the curvature of the cylinder 21.

The downstream end of the portion 24 of the transfer surface 24 is connected almost contiguously with the upper face of the needling table 3.

The transfer table 23 forms with a lower box 28 fixed under the table 23 an air storage chamber 29. The chamber 29 is connected to the outlet, shown schematically by the arrow 31, a blower 32 's feeding itself into 33 in the outside atmosphere, if necessary through unrepresented filters.

The box 28 is attached to an upstream extension 34 of the needling table 3. The assembly constituted by the box 28 and the table 23 is thus made integral with the frame of the needling. The transfer device 22 may be proposed alone to equip a pre-needling or usual needling, if necessary after disassembly of an introducer device which previously fitted this needling. The transfer device 22 to also be an integral part of a pre-needling device designed from the outset with this introducer device according to the invention.

The table 23 is traversed by four rows of air ejection orifices 36, 37, 38, 39. As shown in FIG. 3, the rows are oriented along the width of the sheet, and extend over the entire area. width. The rows are arranged to be substantially equidistant when viewed on the upper face 24 of the table 23. From one row to another, the orifices 36, 37, 38, 39 are arranged in staggered rows (FIG. ). It is therefore schematically that the orifices 36, 37, 38, 39 are shown in the same plane in Figures 1 and 2 and Figures 4 to 6 which will be described later. However, the staggered arrangement is not mandatory and the arrangement shown schematically in Figure 2 could also be adopted.

The orifices 36 to 39 are intended to introduce, between the upper face 24 of the table 23 and the lower face 26 of the sheet, air jets fed by a certain overpressure prevailing in the chamber 29. More particularly, each orifice 36, 37, 38, 39 connects the chamber 29 with the region between the table 23 and the sheet 17, so that the air supplying the chamber 29 from the fan 32 flows in the form of jets 46 to 49 respectively at the outlet of the orifices 36 to 39. These jets combine to form an air flow, a kind of pneumatic bed moving downstream under the ply 17.

Each orifice 36 to 39 is a typically cylindrical conduit formed in the mass of the table 23 and opening perpendicularly into the upstream face 56, 57, 58 or 59 respectively of a recess 41 formed in the upper face 24 of the table 23. there is for each row of orifices 36, 37, 38, 39 a groove-shaped recess 41 extending transversely to the transfer direction 17.

The orifices 36, 37, 38, 39 all have an inclination from upstream to downstream, while following the orifice of the chamber 29 to the upper face 24 of the table 23, and with respect to the inclination local of this In addition, this inclination is increasing from the row of orifices 36 located furthest upstream to the row of orifices 39 situated furthest downstream. Each groove 41 has a shape of V more or less asymmetrical defined by the upstream face 56, 57, 58 or respectively 59, and a downstream face 42. The upstream faces 58 and 59 are steeper than the associated downstream faces 42, relative to the local orientation of the surface 24.

The orifices 36 located upstream are oriented vertically and open through the upward portion 24a of the surface 24. They define levitation jets 46 whose main function is to lift the sheet 17 substantially preventing it from following the part curved path of the slats 19 of the slatted conveyor 18 around the cylinder 21.

The orifices 37, 38, 39 are, in this order, more and more inclined downstream and open through the horizontal part 24 of the transfer surface. They define propulsion jets 47, 48, 49, having a component of movement in the direction of transfer 27 of the ply 17, that is to say a component oriented horizontally downstream relative to the direction of transfer of the fibers. . These jets have a dual function of supporting at least partially the weight of the ply 17 and propel the ply 17 by friction between the air jets 47, 48, 49 on the one hand and the fibers making up the lower face of the ply 17 or more concretely the fibers composing the bottom of the thickness of the sheet 17.

In a typical embodiment, the orifices 36, 37, 38, 39 have a diameter of 1 mm, and are spaced from each other by 20 mm along their respective rows. The spacing between the successive rows may be of the order of 10 mm. The relative pressure prevailing in the accumulation chamber 29 may be of the order of 20 hPa.

In the example shown in Figures 1 and 2, the air jets 46, 47, 48, 49 are continuous.

FIG. 3 shows an alternative embodiment in which shutters 43 are placed against the inside face 44 of the transfer table 23 opposite each row of orifice entries 36, 37, 38 or 39. Each shutter 43 has the example shown in the form of an elongate and flat drawer 51 extending parallel to the row of orifices. Lights 52 made in each drawer are able to coincide simultaneously with the inputs of all the openings of the row and thus make them communicate with the chamber 29. Each drawer 51 is associated with respective actuating means 53 illustrated very schematically by a double arrow, capable of operating the drawers 51 in back and forth parallel to the row of corresponding orifices to alternately open and close the communication of the chamber 29 with the orifices of the row so as to produce air jets which are no longer continuous but pulsed.

It is possible to control the shutters 43 so that all the orifices 36 to 39 are simultaneously open and closed simultaneously. The shutters 43 may also be controlled so that the jets of one row are offset relative to the jets of at least one other row, for example to achieve a kind of peristaltic propulsion of the sheet.

It is also possible for at least one row, for example the row of orifices 36 forming the levitation jets, to be fed continuously, in which case the corresponding shutter is kept in the open position, or even removed, while at least another row produces pulsed jets.

It is also possible for a shutter to have lights 52 whose pitch is different from that of the orifices of the row, for example an irregular pitch if the pitch of the orifices of the row is regular, so that the pulsed jets of a same row are not produced simultaneously. In particular, if it is desired to be able to selectively effect simultaneous or non-simultaneous jets in a row, at least two independently controlled shutters may be provided for this row, each of which is respectively assigned one or more orifices of the row. There may for example be two shutters mounted side by side and each having side teeth selectively hiding the entrance of the corresponding orifices. The teeth of each shutter occupy interdental crenellations of the other shutter.

In a version on the contrary simpler, all the shutters could be combined into a single plate connected to a single actuating means. We would still have, as in the previous examples, the freedom to select the duration of pulsed jets, the time interval between two pulsed jets.

In this embodiment and in the preceding embodiments, it is also possible to provide for certain orifices an elongated light instead of a local orifice to prolong the duration of the jet of certain orifices or even to make certain jets permanent.

In the example shown in Figure 1, the upper face of the web 17 is guided above the table 23 by a system 61 comprising rotating discs 62 which, along their axis oriented transversely to the web, alternate with fixed guide fingers 63 extending downstream to the inlet 14 in the needling 1. The peripheral speed of the discs 62 is preferably slightly greater than that of the web 17.

In the example shown in FIG. 4, the guiding system 61 is replaced by a second blowing transfer device 64.

More particularly, in the example shown, the second transfer device 64 is symmetrical with the device 22 with respect to the plane of the web 17. The device 64 thus comprises a plate 66, symmetrical with the table 23. By orifices 67 made in the plate 66, air jets 69 escape to the upper face 68 of the web 17. The first air jet 69 is directed vertically downwards, the following, relative to the direction of transfer 27, are further in addition inclined downstream and less and less downward.

Thus, in this embodiment, the web 17 is compressed in the direction of the thickness between the two air flows, lower and respectively higher. The sheet is propelled by friction of air both by contact with its lower face 26 and by contact with its upper face 68.

It is preferred that the air jets 69 be less powerful in the vertical direction than the lower air jets 46 to 49. The vertical resultant of the aerodynamic forces is therefore directed upwards, and compensates for at least a portion of the weight of the air. web 17. The friction of the lower face 26 of the web 17 on the table 23 is then reduced or canceled, as in the previous embodiments.

In the example shown, the geometry of the orifices 67 is the same as that of the orifices through the table 23. The least vertical power is obtained by a lower pressure in the upper chamber 71 defined between the plate 66 and a box 72 fixed to an extension 73 of the stripper 4.

But it would also be possible for the upper orifices 67 to be more inclined, and / or in smaller numbers, and / or of smaller diameter and / or, in the case of pulsed jets, controlled with shorter or less frequent pulsations.

The examples of Figures 5 and 6 will be described only for their differences from those of Figure 3 and Figure 2 respectively.

In the example of Figure 5, the sliding drawers 51 are replaced by rotary drawers 151 each consisting of a shaft rotatably mounted in a respective bore formed in the table 23 parallel to the width of the web 17. The bore passes through the orifices of a respective row of orifices 36 to 39. Each shaft comprises, for each orifice of the row, a diametrical duct 152 which coincides with the corresponding orifice, and which thus opens the orifice, in an angular position or a range of angular positions of the shaft. The shaft closes the orifice in other angular positions of the shaft. In this embodiment, the shafts 151 are in continuous rotation (motorization shown schematically by the arrows 153) and can ensure a rate synchronized with the rate of punching needles of the needling machine.

In the example of Figure 6, the transfer device 82 is placed either directly behind the slat conveyor 18, but behind a drive device 74 interposed between the slat conveyor 18 and the transfer device 82. The device drive 74 comprises a counter-rotating lower cylinder 76 and an upper cylinder 77, between which the web 17 is compressed and frictionally driven.

In the versions of Figures 1 to 5, it would also be possible to insert such an intermediate drive device 74 between the slatted conveyor 18 and the lower transfer device 22.

According to another feature, therefore independent of the presence of the driving device 74, the transfer device 82 no longer includes a single chamber such as 29 to supply all the orifices but three chambers 86, 88, 89 which respectively feed the jets 46 and 47 on the one hand, 48 on the other hand, and 49 with respect to the chamber 89 .

It is thus possible to control separately the pressures applied for the production of different jets. For example, the jets 46 and 47 which contribute most to the lift may be produced with greater pressure if the ply 17 is relatively heavy, or on the contrary with more pressure the jets 48 and 49 if the speed of advance of the web 17 must be relatively fast.

The chambers 86, 88 and 89 being of relatively small volume, it is possible to pulse the jet by a solenoid valve or a rotating shutter which would be installed on each of the air supply ducts 87. These can be not connected to the output of a fan, but to a network of compressed air.

Of course, the invention is not limited to the examples described and shown.

The airflow could be created through slit-like openings extending parallel to the width of the web, seeking a kind of floatation of the web over an almost laminar flow, rather than dynamic uplift by jets.

The invention is applicable to the introduction of a nonwoven web into other textile machines, for example a stretching machine.

The invention applies to the transfer of a web following a "substantially horizontal" path, that is to say a path whose orientation normally results in a resistance of the web to advancement, due to gravity and / or inertia and / or friction. For example, the invention would be of particular interest if the path was oblique in the ascending direction.

The connection to a compressed air network is not limited to the realization of Figure 6.

Claims (32)

Process for the transfer of a fiber web (17) along a transfer path (15) at an angle to the vertical, characterized in that in contact with the lower face (26) the web (17) an underlying air flow of which at least a part has a movement component in the direction (27) of the transfer. Process according to Claim 1, characterized in that the jet stream (46, 47, 48, 49) is introduced. Method according to claim 2, characterized in that at least some of the jets are pulsed. Method according to claim 2 or 3, characterized in that at least some of the air jets are propulsion air jets (47, 48, 49) oriented obliquely upwards and in the direction (27) of the transfer of air. the tablecloth. Method according to one of Claims 2 to 4, characterized in that at least some of the air jets are lift jets (46) directed essentially vertically. Process according to one of Claims 1 to 5, characterized in that it is carried out at the outlet of a slatted conveyor (18). A method according to claims 5 and 6, characterized in that the lift air jets (46) are placed just behind the slat conveyor (18) to lift the slick from a region of the slat conveyor which curves around a return means (21). Process according to one of Claims 1 to 7, characterized in that it is carried out at the inlet (14) in a consolidation machine, in particular a needling machine (1). Process according to one of Claims 1 to 8, characterized in that an upper air flow is directed on the upper face (68) of the ply (17), substantially opposite the underlying air flow. Process according to Claim 9, characterized in that at least a part of the upper air flow is given a movement component in the direction (27) of the transfer of the ply (17). Method according to Claim 9 or 10, characterized in that the underlying air flow is given more power than the upper air flow in the vertical direction, so that the vertical resultant of the two air flows balances at least part of the weight of the web. A web transfer device, characterized in that it comprises blowing means for introducing, in contact with the lower face (26) of the web (17), an air flow of which at least a part has a movement component in the direction (27) of the transfer. Device according to claim 12, characterized in that the blowing means are distributed over the width of the web. Device according to claim 12 or 13, characterized in that the blowing means are distributed over a certain length of the path of the web. Device according to claim 14, characterized in that the blowing means are oriented more upwards in an upstream portion of said certain length than in a downstream portion of said length, relative to the direction (27) of transfer of the lap (17). ). Apparatus according to claim 14 or 15, characterized by means for differently setting at least one parameter of pressure and flow at different points of said length. Device according to one of claims 12 to 16, characterized in that it delimits for the lower face (26) of the web a first ascending and then substantially horizontal path. Device according to one of claims 12 to 16, characterized in that the blowing means comprise ejection orifices (36 to 39). Device according to one of Claims 12 to 18, characterized in that at least some of the orifices (37 to 39) are oriented to define air jets (47 to 49) directed downstream relative to the direction (27). transfer of the web (17). Device according to claim 18 or 19, characterized in that some of the orifices (36) are oriented to define substantially vertical air jets (46). Device according to one of claims 18 to 20, characterized in that the orifices (36 to 39) open into at least one recess (41) of a surface (24), this recess having, relative to the direction of transfer, a upstream face (58, 59) on a steep slope and a downstream face (42) in gentle slope. Device according to claim 21, characterized in that the recesses are grooves transverse to the direction of transfer. Device according to one of claims 19 to 22, characterized in that the orifices (36 to 39) are arranged in staggered rows. Device according to one of claims 19 to 23, characterized in that the orifices have an inlet communicating with at least one accumulation chamber (29) connected to an air supply means (32). Device according to one of claims 19 to 24, characterized in that it comprises movable shutter means (43, 143) for the orifices. Device according to one of claims 12 to 24, characterized by shutter means placed in the air path (87) of the blowing means. Device according to claim 25 or 26, characterized by means (53, 153) for controlling the shutter means (43, 152) so as to generate a pulsating air flow. Device according to one of claims 12 to 27, characterized in that it comprises blowing means (64) on the upper face (68) of the ply (17), to generate an upper air flow part of which at least one movement component in the direction (27) of transfer of the web (17). Device according to one of claims 12 to 28, characterized in that it comprises a table (23) under the path of the web. Device according to claim 29, characterized in that the table (23) comprises an anti-friction coating. Consolidation machine comprising a sheet inlet equipped with a device according to one of claims 12 to 30. Machine according to claim 31, characterized in that the machine is a needling machine, in particular a pre-needling machine (1).

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