EP0530100A1 - Method for laying a non-woven, non-woven product and non-woven laying device used in the method - Google Patents

Abstract

An unwinding carriage (14) is supplied with a fibre web (4). This unwinding carriage (14) is moved to and fro, thus causing it to deposit the web (4) onto an exit conveyor (8) driven transversely to the movement of the unwinding carriage (14), so as to produce a lap (6) consisting of successive lengths of web inclined alternately relative to the longitudinal direction of the exit conveyor (8), these lengths being connected by means of folds defining the edges of the lap produced (6). The advance of the exit conveyor (8) is maintained at the moments of the changes in direction of the unwinding carriage (14). During these changes in direction, the quantity of web (4) unwound is restricted, so as to exert on the fibres between the exit conveyor (8) and the unwinding carriage (14) a pull which tends to orient the fibres forming the folds of the web in the lap (6) parallel to the longitudinal direction of the exit conveyor (8). The invention is used particularly for making needled products. <IMAGE>

Description

The present invention relates to a topping process for producing a nonwoven web.

The present invention also relates to a nonwoven coated product obtainable by the process.

The present invention further relates to a spreader-lapper for implementing the method and obtaining the product.

Conventional spreader-lappers are known, for example according to DE-B-19 27 863, in which a reeling carriage carries out back and forth transverse over a movable output conveyor at constant speed.

When the unwinding carriage is in one or other of its end positions, it must stop to change its direction of movement, while it continues to unwind the web at unchanged speed on the output belt. However, since the relative speed between the carriage and the exit belt has greatly decreased since it no longer comprises the transverse component of the movement of the unwinding carriage, the web is unwound in excess. These traditional machines thus form large lateral beads which must then be eliminated in order to obtain a product having an approximately regular weight per unit of area at all points of its width.

We know from FR-B-2 234 395 to remedy these drawbacks on the one hand by giving the output belt a speed which fluctuates in proportion to the absolute value of the speed of the unwinding carriage, in particular so that the output conveyor is at a standstill when the reeling carriage is itself at a standstill when it changes direction of travel, and on the other hand by giving the feed trolley located upstream of the reeling carriage a law of motion such as the reel carriage delivers the veil to a speed which is itself proportional to the speed of the conveyor belt and to the absolute value of the speed of the reeling carriage.

Thus, the amount of haze deposited per unit area of the exit conveyor is theoretically constant, and consequently the coated product produced is theoretically perfectly regular.

Furthermore, as a result of the lapping operation, the initially longitudinal fibers of the web which supplies the spreader-lapper are arranged transversely in the web, with a certain angle of inclination for example less than 15 °. As a result, the tensile strength of the sheet is much lower in the longitudinal direction of the sheet than in its transverse direction, which almost coincides with the orientation of the fibers. This is a drawback because the sheet is an intermediate product intended to undergo subsequent transformations, in particular by needling, during which it is pulled in the direction of its length. It is thus in the direction of the length that one would wish the best tensile strength. The poor tensile strength which must currently be accommodated for conducting needling or other operations limits the speed of work and produces transverse shrinkage during needling, and this shrinkage tends to create excess thickness at the edges.

The object of the present invention is to propose a lapping process, a lapped product, and a spreader-lapper which overcomes these drawbacks and makes it possible in particular to very simply produce a lapped product having good resistance to longitudinal traction.

According to the invention, the lapping process in which a reeling carriage is fed with a veil comprising fibers directed substantially parallel to the length of this veil, while this reeling carriage is moved back and forth over an output mat by making it deposit the veil on the output mat driven according to a direction which is transverse to the direction of movement of the unwinding carriage, so as to produce a sheet made up of successive sections inclined once in one direction and once in the other with respect to the longitudinal direction of the output conveyor, these sections being connected by folds defining the edges of the web produced, process in which the advance of the output belt is maintained at the time of the change of direction of movement of the reeling carriage, is characterized in that, at said time, it restricts the amount of web unwound by the unwinding carriage towards the exit belt so as to exert on the fibers between the exit belt and the unwinding carriage a tension tending to orie nter parallel to the longitudinal direction of the exit belt the fibers constituting the folds of the veil in the sheet.

There is thus formed along the two longitudinal edges of the sheet a kind of cord made up largely of fibers oriented longitudinally. These cords thus have an amazing tensile strength and constitute, for the rest of the treatment, in particular during needling, a sort of tensile reinforcement which considerably strengthens the ply with regard to the deformations tending to occur under the effect of traction.

It is then possible, for example after the needling operation, to eliminate the two lateral cords whose thickness, apparent density and structure do not conform to those of the rest of the ply.

This is certainly waste but, surprisingly, this waste, accepted in principle in the process according to the invention, ultimately turns out to be significantly less bulky than that entailed by many other processes which should theoretically produce no waste. The side strip to be cut on each side of the ply may for example be 50 mm wide according to the invention instead of 150 mm in certain known methods.

In addition, the invention makes it possible to minimize the transverse shrinkage during needling and consequently the needled product obtained has better regularity in weight.

According to a second object of the invention, the nonwoven coated product is characterized in that it comprises in its lateral edges portions of fibers directed longitudinally and forming an obtuse angle with other portions of the same fibers directed obliquely towards the central part of the product.

According to a third object of the invention, the spreader-lapper comprising means of transport for defining a path for transporting a veil to a mobile reeling carriage back and forth over a carpet movable output transverse to the direction of back-and-forth of the unwinding carriage, is characterized by means for giving the output belt a speed substantially proportional to the absolute value of the speed of the unwinding carriage except in time intervals including the moments of change of direction of movement of the unwinding carriage, during which the speed of the output conveyor is greater than that which would result from the calculation of proportionality with respect to the absolute value of the speed of the unwinding carriage, and by means for causing the web to be unwound by the reeling carriage at a speed which is proportional to the speed of the output belt except at time intervals including the moments of change of s ens of movement of the wire feed carriage, during which the wire feed speed is lower than that which would result from the calculation of proportionality with respect to the speed of the output belt.

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

• la figure 1 est une vue extérieure en perspective d'un étaleur-nappeur ;
• la figure 2 est une vue schématique en élévation d'un exemple d'étaleur-nappeur conforme à l'invention ;
• la figure 3 est une vue agrandie d'une partie de la vue de la figure 2 ;
• la figure 4 représente un graphique illustrant les vitesses instantanées de différents composants de l'étaleur-nappeur ; et
• la figure 5 est une vue en perspective illustrant le dépôt du voile sur le tapis de sortie de l'étaleur-nappeur.

In the accompanying drawings:

• Figure 1 is an external perspective view of a spreader-lapper;
• Figure 2 is a schematic elevational view of an exemplary spreader-lapper according to the invention;
• Figure 3 is an enlarged view of part of the view of Figure 2;
• FIG. 4 represents a graph illustrating the instantaneous speeds of different components of the spreader-lapper; and
• Figure 5 is a perspective view illustrating the deposition of the veil on the output belt of the spreader-lapper.

A spreader-lapper is shown in perspective in Figure 1.

A first conveyor belt 2, known as the front conveyor, collects the web of fibers 4, for example from a card not shown, and transports it into the enclosure 1 of the spreader-lapper where it is transformed by folding into a ply 6 of width L transported by an exit conveyor 8 outside the spreader-lapper. The veil 4 is made up of fibers essentially directed parallel to its length. The output belt 8 can transport the formed sheet 6 to a needling machine not shown. The directions of transport of the web 4 and of the web 6 are indicated in FIG. 1 by the respective arrows F and K. For the purposes for reference, the side 7 adjacent to the face through which the web 4 penetrates will be called "front side" of the spreader-lapper and side 9 opposite the front side 7 is "rear side" of the spreader-lapper.

The interior of the spreader-lapper is shown diagrammatically in the elevation view of FIG. 2, taken along a plane Q (see FIG. 1) perpendicular to the direction of transport of the ply 6 by the output conveyor 8 to l outside of the spreader-lapper.

In addition to the front conveyor 2, the spreader-lapper comprises a second conveyor belt 5, called the rear conveyor. The conveyors 2 and 5, shown in solid lines in FIG. 2, have the same width and have their lateral edges in the same planes parallel to the plane Q of FIG. 2. The front conveyor 2 follows a closed path defined by rollers of cylindrical guide 32 to 43. The rear conveyor 5 follows a closed path defined by cylindrical guide rollers 60 to 69.

The guide rollers 32 to 43, 60 to 69 are pivotally mounted around respective axes which are all horizontal and perpendicular to the plane Q of Figure 2, that is to say substantially parallel to the direction of movement of the conveyor belt. outlet 8. These guide rollers 32 to 43, 60 to 69 include rollers 32, 33, 39, 40, 42, 43 and 65, 66, 68, 69 whose axis is fixed relative to the chassis 1 of the spreader-lapper, rollers 34, 35 and 60, 61, 62, 63 carried by a first movable main carriage 10, called feed trolley, rollers 36, 37, 38 and 64 carried by a second movable main carriage 14, said unwinding carriage, and rollers 41 and 67 carried by auxiliary carriages 16, 18. The auxiliary carriages 16, 18 each carry a guide roller 41, 67 corresponding to one of the conveyors 2, 5. The two auxiliary carriages 16, 18 have movements which compensate for those of the main carriages 10, 14 to keep constant the length of each of the closed paths followed by the carriers 2, 5. Between the main carriages 10, 14 and the auxiliary carriages 16, 18, the carriers 2, 5 are guided by rollers with fixed axis located on the sides 7, 9 of the spreader-lapper, on either side of the output conveyor 8.

The main carriages 10, 14 are located above the output conveyor 8 and are movable in translation in a horizontal direction and perpendicular to the axes of the rollers 32 to 43, 60 to 69.

In service, the main carriages 10, 14 are moved back and forth in this direction.

A first toothed belt 84, shown in dashed lines in FIG. 2, has its ends fixed on the feed carriage 10 and on the first auxiliary carriage 16. The toothed belt 84 is guided between its two carriages 10, 16 by pinions 85 , 86 located on the rear side 9 of the spreader-lapper. These two carriages 10, 16 are also coupled by a cable 92, shown in phantom in Figure 2, passing through the front side 7 of the spreader-lapper, and guided by pulleys 93, 94. The pinion 86 meshing with the toothed belt 84 is driven by a motor 24. When the motor 24 drives the pinion 86 in a first direction, the feed carriage is pulled towards the rear side 9 of the spreader-lapper, so that, by the 'Intermediate of the cable 92, the associated auxiliary carriage 16 is pulled with the same speed towards the front side 7 of the spreader-lapper. When the motor 24 drives the pinion 86 in the other direction, the auxiliary carriage 16 is pulled towards the rear side 9 of the spreader-lapper, so that, via the cable 92, the feed carriage 10 is pulled with the same speed to the front side 7 of the spreader-lapper.

A similar assembly is provided for driving the reeling carriage 14 and its associated auxiliary carriage 18. A second toothed belt 88, shown in dashed lines in FIG. 2, has its ends fixed on the reeling carriage 14 and on the carriage auxiliary 18. The toothed belt 88 passes through the front side 7 of the spreader-lapper bypassing two pinions 89, 90. These two carriages 14, 18 are also coupled by a second cable 96, shown in phantom in the figure 2, passing through the rear side 9 of the spreader-lapper and guided by two pulleys 97, 98. The pinion 90 meshing with the toothed belt 88 is rotated by a motor 25. When the motor 25 drives the pinion 90 in a first direction, the unwinding carriage 14 is pulled towards the front side 7 of the spreader-lapper, so that, via the cable 96, the associated auxiliary carriage 18 is pulled with the same speed towards the rear side 9 of the spreader-lapper. When the motor 25 drives the pinion 90 in the other direction, the auxiliary carriage 18 is pulled towards the front side 7 of the spreader-lapper, so that, via the cable 96, the unwinding carriage 14 is pulled with the same speed towards the rear side 9 of the spreader-lapper.

The circulation of the front conveyor 2 along its closed path is ensured by a motor 26 which rotates one of the guide rollers 43 of the front conveyor 2. Likewise, the circulation of the rear conveyor 5 along its closed path is provided by a motor 27 which rotates one of the guide rollers 65 bypassed by the rear conveyor 5.

As can be seen in FIG. 2 and in the more detailed view of FIG. 3, the web 4 is brought up to feed carriage 10 by the front conveyor 2. On the feed carriage 10, the web 4 makes a 180 ° turn to enter a nip 23 in which it is held between the two conveyors 2, 5. The nipping zone 23 ends at the unwinding carriage 14 which deposits the web 4 on the output belt 8.

The back and forth movement of amplitude L of the unwinding carriage 14 ensures that the web 4 is deposited on the output belt 8 by alternating plies, so as to form a ply 6 made up of successive webs of web. As the output belt 8, driven by a motor 28 moves perpendicular to the direction of movement of the unwinding carriage 14, the successive sections of sail are inclined once in one direction and once in the other with respect to the direction longitudinal of the output conveyor 8. The alternating folds which connect the panels together are therefore offset with respect to the longitudinal direction of the ply 6 and define the lateral edges thereof (see FIG. 5).

We will now describe the kinematic laws applied by the different motor means of the spreader-lapper, namely the motor 24 for driving the feed carriage 10, the motor 25 for driving the wire feed carriage 14, the motor 26 for circulation of the front conveyor 2, the motor 27 for circulation of the rear conveyor 5, and the motor 28 for driving the output conveyor 8.

The motors 24, 25, 26, 27, 28 can be controlled independently, for example electronically, to apply these kinematic laws. As a variant, it is possible to provide suitable transmission mechanisms to obtain the desired speed dependencies between the different moving parts (an example of this type of mechanism is provided in FR-B-2 234 395).

Referring to FIG. 3, denote by v the speed of supply of the web 4 to the entry of the spreader-lapper, by u the algebraic speed of the feed carriage 10 and by w the algebraic speed of the carriage unwinding 14. The speed v of supply of the web 4 is always counted positive and the algebraic speeds u , w of the carriages 10, 14 are counted positive in the direction indicated in FIG. 3, where the carriages 10, 14 move in the direction identical to the direction of supply of veil 4, and negative in the opposite direction. The speed v , generally constant, is imposed by the flow rate of the card located upstream of the spreader-lapper. The speeds u and w are applied respectively by the motors 24 and 25.

The motor 26 for circulation of the front conveyor 2 is adjusted to apply a speed equal to speed v in the sections where it receives the web 4 upstream of the feed carriage 10. The motor 27 for circulation of the rear conveyor 5 is adjusted to apply to it upstream of the feed carriage 10 a speed x (see FIG. 3) equal to v - 2u so that the two conveyors 2, 5 have the same speed in the nip 23.

Under these conditions, the speed y of unwinding the web 4 by the unwinding carriage 14 to the output belt 8 is equal to x + w = v - 2u + w.

In FIG. 5, the speed z is applied to the output conveyor 8 by its drive motor 28.

FIG. 4 represents examples of chronograms of the speeds u , w , x and z which can be applied respectively by the motors 24, 25, 27 and 28 (the constant chronogram of the speed v applied by the motor 26 has not been shown ). Figure 4 also shows, in dashes, the timing of the speed of unwinding y resulting from the speeds applied by the different motors.

The speed w of the unwinding carriage 14, shown in thick line in FIG. 4, follows an alternative periodic law as a function of time t , each alternation corresponding to a section of the ply 6 formed on the output conveyor 8. The speed w can for example follow a sinusoidal law. In the example shown, the unwinding carriage 14 marks a brief downtime of duration d when it changes direction.

$$\text{u = v/2 lorsque w≧0}$$

The motor 24 driving the feed carriage 10 is adjusted so that its speed u satisfies the following relationships (curve in solid line in FIG. 4): $$\text{u = w + v / 2 when w <0}$$

$$\text{u = v / 2 when w ≧ 0}$$

The motor 27 is then adjusted so that it drives the rear conveyor 5 at the speed x = v - 2u, the curve of which is drawn in dotted lines in FIG. 4. Under these conditions, the speed y of unwinding of the web 4 is equal to each instant at the absolute value of the speed of translation w of the unwinding carriage 14. It will be noted that the unwinding of the web 4 is interrupted (y = 0) during the downtimes d corresponding to the changes of direction of the unwinding carriage 14 .

The motor 28 is adjusted so that the instantaneous speed z of the output belt 8 is proportional to the speed y of unwinding of the web 4, and therefore proportional to the absolute value of the speed w of the unwinding carriage, the ratio a = z / | w | = z / y defining the average angle between the fibers of each section of the deposited web and the transverse direction of the web 6. But, for a short time interval D including each stop time d of the unwinding carriage 14, the motor 28 applies to the output conveyor 8 a speed z no zero, that is to say a speed which is greater than that which would result from the calculation of proportionality to the speed y according to the ratio a . The advance of the output belt 8 is therefore uninterrupted even when the direction of movement of the reeling carriage 14 changes. In other words, during the time intervals D, the quantity of web 4 unloaded by the carriage is restricted of unwinding 14 towards the output conveyor 8 with respect to the speed z of the output conveyor 8. Thus, when the direction of movement changes of the unwinding carriage 14, it is exerted on the fibers between the output conveyor 8 and the unwinding carriage 14 a pull tending to orient, parallel to the longitudinal direction of the output belt 8, the fibers constituting the folds of the web at the edges of the sheet 6.

FIG. 5 schematically illustrates the nonwoven lapped product 6 obtained on the output belt 8, and shows the unwinding carriage 14 when it changes direction over an edge of the web 6. At this time, the speed z of the output conveyor 8 is not zero and the unwinding of the web 4 is restricted or interrupted ( y = 0). The lateral edges of the ply 6 then comprise portions of fibers oriented substantially longitudinally and forming an obtuse angle with other portions of the same fibers included in inclined sections of veil and directed obliquely towards the central part of the ply 6.

Due to these longitudinally oriented portions of fibers, the lapped product 6 has satisfactory resistance to longitudinal traction. In addition, during a subsequent needling, it will undergo an advantageously moderate transverse withdrawal.

Although a specific embodiment of the present invention has been described, it will be noted that various modifications can be made to it without out of the scope of the invention.

Thus, an example has been described in which the speed y of unwinding of the web 4 is at each instant equal to the absolute value of the speed w of movement of the unwinding carriage 14. According to the invention, it is generally preferred that this speed unwinding y is proportional to | w |, the case of equality described being a particular example wherein the ratio of proportionality is 1.

In addition, it will be clear to a person skilled in the art that the method according to the invention can be implemented with spreaders-lappers different from that described by way of example with reference to FIGS. 1 to 3.

Claims (10)

Laying method, in which a reel carriage (14) is fed with a veil (4) comprising fibers directed substantially parallel to the length of this veil, while this reel carriage (14) is moved back and forth - comes above an output mat (8) by making it deposit the web (4) on the output mat (8) driven in a direction which is transverse to the direction of movement of the reel carriage (14) , so as to produce a ply (6) consisting of successive sections of sail inclined once in one direction and once in the other with respect to the longitudinal direction of the exit conveyor (8), these sections being connected by folds defining the edges of the sheet produced (6), method in which the advance of the output belt (8) is maintained at the time of the change of direction of movement of the reeling carriage (14), characterized in that, at said time, we restrict the amount of veil (4) unwound by the devida carriage ge (14) towards the exit mat (8) so as to exert on the fibers between the exit mat (8) and the unwinding carriage (14) a pull tending to orient parallel to the longitudinal direction of the exit mat ( 8) the fibers constituting the folds of the veil in the web (6). Method according to claim 1, characterized in that the unwinding of the web (4) by the reeling carriage (14) is interrupted when the direction of movement of the reeling carriage (14) is changed. Method according to one of claims 1 or 2, characterized in that the reeling carriage (14) is fed via a feeding carriage (10), and in that the two carriages (10, 14) so as to satisfy the following relationships:
the speed (u) of the feed carriage (10) is equal to the algebraic sum of the speed (w) of the wire feed carriage (14) and half the speed (v) of the web feed (4) when the reeling carriage (14) moves in the opposite direction to the direction of supply of the web (4) and,
the speed (u) of the feed carriage (10) is equal to half the speed (v) of feeding of the web (4) when the unwinding carriage (14) moves in the same direction as the direction of bringing the veil (4),
relations in which the speed (v) of supply of the web (4) is always counted positive and the speeds (u, w) of the carriages (10, 14) are counted positive in their direction corresponding to the second relation. Method according to one of claims 1 to 3, characterized in that the output conveyor (8) is moved at a speed (z) which is proportional to the absolute value of the speed (w) of the unwinding carriage (14) ) at any time except in time intervals (D) including the moments of change of direction of movement of the unwinding carriage (14), during which the output conveyor (8) is moved at a speed which is higher than that which would result from the proportionality calculation with respect to the absolute value of the speed of the reeling carriage (14). Method according to one of claims 1 to 4, characterized in that the web (4) is unwound by the unwinding carriage (14) at a speed (y) which is proportional to the speed (z) of the mat. output (8) except at time intervals (D) including changes of direction of movement of the wire feed carriage (14), during which the wire feed speed (y) is lower than that which would result from the calculation of proportionality with respect to the speed (z) of the output belt (8). Method according to one of claims 1 to 5, characterized in that the speed (y) of unwinding the web (4) by the unwinding carriage (14) is at all times substantially proportional to the absolute value of the speed (w ) for moving the reeling carriage (14). Nonwoven coated product (6) characterized in that it has in its lateral edges portions of fibers directed longitudinally and forming an obtuse angle with other portions of the same fibers directed obliquely towards the central part of the product. Layer spreader comprising transport means (2, 5) for defining a transport path from a web (4) to a reeling carriage (14) movable back and forth over a carpet output (8) movable transversely to the direction of back and forth of the unwinding carriage (14), characterized by means (28) to give the output conveyor (8) a speed (z) substantially proportional to the value absolute speed (w) of the unwinding carriage (14) except in time intervals (D) including the moments of change of direction of movement of the unwinding carriage (14), during which the speed (z) of the belt output (8) is greater than that which would result from the calculation of proportionality with respect to the absolute value of the speed (w) of the reeling carriage (14), and by means (24, 25, 26, 27) for making unwind the web (4) by the unwinding carriage (14) at a speed (y) which is proportional to the speed (z) of the output belt (8) except in de s time intervals (D) including the moments of change of direction of movement of the reeling carriage (14), during which the speed (y) of reeling of the web (4) is lower than that which would result from the proportionality calculation with respect to the speed (z) of the output belt (8). Spreader-lapper according to claim 8, characterized in that the web (4) is unwound at a speed (y) proportional to the absolute value of the speed (w) of the reeling carriage (14). Layer spreader according to one of claims 8 or 9, further comprising a movable feed carriage (10) for supplying the web with the reel carriage (14), characterized by means (24, 25) for driving the carriage feed (10) and the wire feed carriage (14) respecting the following relationships:
the speed (u) of the feed carriage (10) is equal to the algebraic sum of the speed (w) of the wire feed carriage (14) and half the speed (v) of the web feed (4) when the unwinding carriage (14) moves in the opposite direction to the direction of supply of the web (4), and
the speed (u) of the feed carriage (10) is equal to half the speed (v) of feeding of the web (4) when the unwinding carriage (14) moves in the same direction as the direction of bringing the veil (4),
relations in which the speed (v) of supply of the web (4) is always counted positive, and the speeds (u, w) of the carriages (10, 14) are counted positive in their direction corresponding to the second relation.

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