EP1798175A1 - Transport of a non-woven band by means of a conveyor belt with an ascending portion and/or variable speed - Google Patents

Abstract

A nonwoven web (WE) is conveyed by means of a conveyor belt (100) having at least one transport portion (100a) which is upward and / or which undergoes changes of speed. During transport, the web of nonwoven (WE) and / or the transport belt (100) is electrostatically charged so as to adhere the nonwoven web to the surface of the transport belt in said portion. transport (100a) ascending and / or variable speed. Application: transport of a web of nonwoven (WE) at the entrance of a crosslapper (1).

Description

The present invention relates to an improvement in the textile field, transporting a web of nonwoven by means of a conveyor belt having an upward transport portion and / or variable speed. The present invention can be implemented with any type of nonwoven (nonwoven carded, "spun", "metlblown", "airlaid"). It finds preferentially, but not exclusively, its application to the input of a crosslapper.

Prior art

In the present text, the term "nonwoven web" generally designates any web of fibers and / or filaments or superposition of webs of fibers and / or filaments, regardless of the method of manufacture. the sail or sails, and the type of fibers or filaments. In particular, the nonwoven web may consist of a single web of fibers or filaments (monolayer nonwoven web) or of several superimposed webs of fibers or filaments (multilayer nonwoven web), or the sails being chosen from the list: nonwoven carded fleece, airlaid nonwoven fleece, meltblown nonwoven fleece, spun nonwoven fleece. In the case of a plurality of superimposed sails, all the sails may be of the same type, or the nonwoven may be composite, that is to say composed of several sails of different types such as for example a composite nonwoven of type CMC (carded sail / sail "meltblown" / sail carded) or type SMS (sail "spun" / sail "meltblown" / sail "spun")

It is recalled that a nonwoven generally undergoes at a later stage of its constitution one or more consolidation steps, such as in particular mechanical bonding, for example by needling, hydraulic bonding by water jets, thermoling by calendering, or chemical bonding. for example by means of an adhesive. In this text, the term "nonwoven web "Indifferently designates the veil or the superposition of veils of fibers and / or filaments before consolidation or after consolidation.

In order to transport a non-woven web (in the course of manufacture or after manufacture to undergo subsequent processing steps), it is known to use a belt conveyor comprising an endless conveyor belt which is wound on means rotary drive, roll type, the nonwoven web being in contact with the conveyor belt. Depending on the application, the conveyor belt is impermeable or breathable.

In some applications, an endless conveyor belt is used that has a more or less complex path, with at least one portion of upward transport. This is the case, for example, for the conveyor belt which is used at the entrance of a crosslapper, such as that described for example in the international patent application. WO92 / 21799 .

In an upward conveying portion of a conveyor belt, the nonwoven web tends to slip under the effect of gravity relative to the conveyor belt. This slip phenomenon is accentuated in the case of a smooth conveyor belt, and also increases with the angle of inclination and / or the weight of the nonwoven web. In addition, in the case of a non-consolidated multilayer non-woven strip, the different superposed layers, which are not linked together, also have a tendency to slide relative to each other, which is detrimental to the quality non-woven. This slippage is also accentuated when the conveyor belt undergoes sudden changes in speed (acceleration and deceleration), which is the case for example for the conveyor belt input of certain types of spreader-lapper.

These various constraints related to the sliding of the nonwoven web result in practice in limiting the speed of movement of the conveyor belt at the expense of, in particular, the production rate, and / or in limiting the angle of inclination of the portion ascending transport, and / or to limit the accelerations and or decelerations of the conveyor belt.

Objective of the invention

The present invention aims to propose a new technical solution to the aforementioned problem of sliding a nonwoven web in an upward transport portion and / or driven with a variable speed.

Summary of the invention

In general, the solution of the invention is to electrostatically charge the nonwoven web and / or the conveyor belt, so as to adhere the nonwoven web against the surface of the conveyor belt. said upward transport portion and / or variable speed.

The invention thus has as its first object a method of transporting a nonwoven web by means of a conveyor belt comprising at least one transport portion which is ascending and / or which undergoes changes of speed. According to the invention, the nonwoven web and / or the conveyor belt is electrostatically charged so as to adhere the nonwoven web to the surface of the conveyor belt in said upward transport portion and / or variable speed.

Another object of the invention is an assembly for transporting a nonwoven web, said assembly comprising a conveyor belt having at least one transport portion which is upward and / or which is subject to changes in speed. According to the invention, said transport assembly comprises ionization means which, in operation, make it possible to electrostatically charge the nonwoven web and / or the transport belt, so as to adhere the nonwoven web to the surface of the conveyor belt in said ascending transport portion and / or variable speed.

Another object of the invention is a spreader-lapper which comprises as input a transport assembly mentioned above.

Brief description of the figures

• la figure 1 représente de manière schématique et en perspective un étaleur-nappeur conforme à l'invention et équipé en entrée de moyens d'ionisation, et
• la figure 2 est une vue schématique de coté de l'étaleur-nappeur de la figure 1.

Other features and advantages of the invention will appear more clearly on reading the following detailed description of a preferred embodiment of the invention, which description is given by way of non-limiting and non-exhaustive example of the invention and with reference to the accompanying drawings in which:

• FIG. 1 schematically and in perspective shows a crosslapper in accordance with the invention and equipped at input with ionization means, and
• FIG. 2 is a schematic side view of the crosslapper of FIG. 1.

detailed description

FIGS. 1 and 2 show a crosslapper 1 fed at the input with a web of nonwoven WE. In FIG. 1, the input and the output of the crosslapper 1 are referenced respectively E and S.

The nonwoven WE web may be of the monolayer type or the multilayer type, and is made of fibers and / or filaments forming a dielectric material. These are, for example, synthetic fibers or filaments based on polypropylene or polyethylene, and / or natural fibers or filaments of the cotton type, and / or artificial fibers or filaments of the viscose type.

This unconsolidated web WE web is for example manufactured upstream of the crosslapper 1 by a production machine (not shown) such as for example a nonwoven card, and is conveyed to the entrance E of the crosslapper 1 by any known means of transport, and for example by means of a belt conveyor T which is shown only in FIG.

The structure and operation of the crosslapper 1 are known to those skilled in the art and will therefore not be detailed in the present description. For the sake of simplification and conciseness, only Technical elements of the crosslapper 1 necessary for the understanding of the present invention will be described hereinafter. For a complete understanding of the structure and operation of the crosslapper 1, one skilled in the art can refer for example to the text of the international patent application WO 92/21799 .

With reference to FIGS. 1 and 2, the crosslapper 1 comprises two belt conveyors 10 and 11, and an output band conveyor 14.

The conveyor belt 10 comprises an endless conveyor belt 100 which is wound in a closed path on guide rollers 101a to 101l, at least one of which is motorized for driving the conveyor belt 100 The conveyor belt 100 may, regardless of the invention, be permeable or impermeable to air.

Among these guide rollers, the two rear guide rollers 101a, 101b are usually embarked on an upper movable entry trolley 12, and are mounted free to rotate about their central axis with respect to this trolley 12. The rolls of 101j, 101 k and 101 are usually embarked on a lower output carriage 13 movable, and are rotatably mounted according to their central axis relative to the carriage 13. The upper carriage 12 and the lower carriage 13 are movable in translation, and are equipped with drive means (not shown) for moving them in translation alternately in the two opposite directions D and G.

The belt conveyor 11 comprises a conveyor belt 110 which is wound in a closed path on guide rollers 111a to 111j at least one of which is motorized for driving the conveyor belt 110. The guide rollers 111 a to 111 d are usually embedded on the carriage 12 mobile, and are mounted free in rotation along their central axis relative to the carriage 12. The guide roller 111e is embedded on the carriage 13, and is mounted freely in rotation along its central axis relative to this carriage 13.

In operation, the carriages 12 and 13, and thus the guide rollers which are embedded on these carriages, are synchronously animated with a translational movement back and forth in the opposite directions D and G.

The nonwoven web WE (produced upstream of the crosslapper for example by means of a not shown card) is deposited at the input E of the crosslapper 1 at the surface of the conveyor belt. This web of WE fleece is conveyed by the conveyor belt 100 to a nipping zone of the nonwoven web between the two conveyor belts 100 and 110 (between the guide rolls 111). and 101j). Due to the synchronized back-and-forth movements of the carriages 12 and 13, the non-woven WE web is reciprocated back and forth in the opposite directions G and D, which allows the nonwoven web to be folded alternately. WE on itself at the surface of the conveyor belt 140 of the output conveyor 14. This conveyor belt 140 is oriented transversely to the direction of entry (arrow F) of the nonwoven web WE and is movable in the direction of the arrow K (Figure 1). At the output S of the crosslapper 1, there is obtained a thick multilayer nonwoven web WS, formed of a plurality of layers of nonwoven web WEa, WEb, WEc, ..., which overlap, said web WS being carried out in direction K.

With reference to FIG. 2, the input conveyor belt 100 comprises an ascending straight portion 100a, which extends between the two guide rollers 101d and 101c, and whose inclination relative to the horizontal is referenced by the angle A. The height position of the guide roller 101d is preferably adjustable, so that the value of this angle of inclination A is adjustable. Also in some cases, the height position of the guide roller 101d is variable during operation, so that the value of this angle of inclination A varies during the movement of the conveyor belt. 100.

In order to avoid a slippage of the nonwoven web WE in the upward portion 100a of the input conveyor belt 100, the crosslapper 1 of the invention is equipped with ionization means, which in the particular embodiment of the appended figures, are in the form of an ionizing bar 15. In this embodiment, the input conveyor belt 10 is made of an electrically conductive material (for example of metal) and acts as a mass connected to the earth.

In operation, the ionizing bar 15 generates a strong ion-saturated electric field 15a, referred to as an ionizing field, and symbolized by dotted lines in FIG. 2. For this purpose, the ionizing bar 15 comprises, for example, a plurality of electrodes or high voltage peaks which are powered by a high-voltage DC generator (not shown) and which can locally generate ions, for example negative.

More particularly, the ionizing bar 15 is mounted above and close to the surface of the upward portion 100a of the conveyor belt 100, and extends transversely to the direction of travel F of the upward portion 100a of the conveyor belt 100.

Preferably, as illustrated in FIGS. 1 and 2, the ionizing bar 15 is positioned in the vicinity of the guide roll 101 d, that is to say at the entrance of the ascending portion, immediately downstream of the transition region between the upstream carrier T and the input carrier 10.

More particularly, the ionization means 15 generate an ionizing field 15a which preferably extends over at least the entire width (L) of the nonwoven web WE.

In operation, when the nonwoven web WE passes into the ionizing field 15a, the fibers and / or filaments of said nonwoven web WE are electrostatically charged, and are plated by their electrostatic charge against the surface of the conveyor belt in the ascending portion 100a. The nonwoven web WE thus adheres strongly to the surface of the conveyor belt 100 in its ascending portion 100a. This electrostatic retention of the nonwoven web WE advantageously avoids the slip phenomena of the nonwoven web WE in this upward transport portion 100a. It is thus possible, in particular, to transport the nonwoven web WE in the upward portion 100a with higher speeds and / or to transport heavier WE webs and / or to increase the angle of inclination. A from the upward portion, without prejudice to the quality of the nonwoven web WE.

In operation, the web of nonwoven WE, once it has crossed the ionizing field 15a and electrostatically charged during its passage in the ionizing field 15a, then discharges progressively through the band of transport 100.

Preferably, but not necessarily, the ionization means 15 are provided such that the electrostatic charge of the WE web is sufficient to electrostatically adhere the WE web to the surface of the WE web. transport 100 at least until the end of the upward transport portion 100a, that is to say in the example shown up to the guide roller 101c.

Depending on the application, and in particular as a function of the length of the upward portion, it is possible for example to provide at the level of the upward portion 100a, one or more additional ionizing bars so as to electrostatically recharge the strip of woven WE in said ascending portion 100a. It is also possible to provide additional ionization means downstream of the upward portion 100a, such as for example the ionizing bar 15 'in Figure 2.

The ionizing bar 15 may be replaced by any equivalent means making it possible to electrostatically adhere the strip of nonwoven WE against the conveyor belt 100 at least in the ascending portion 100a. In particular, the ionizing bar 15 can be replaced by a plurality of juxtaposed ionizing sources of smaller dimension. Also, in another variant, it is the conveyor belt 100 that can be electrostatically charged; in another variant, both the nonwoven web WE and the conveyor belt 100 may be electrostatically charged and with opposite polarities.

Although it is preferable that the nonwoven web WE and / or the conveyor belt 100 is electrostatically charged over at least the entire width L of the nonwoven web WE, this characteristic is however not essential. In another variant embodiment, it may be sufficient to electrostatically charge, and thereby to electrostatically adhere the nonwoven web WE, over only a portion of its width, and for example locally at its two. edges or locally in a central region that does not extend to the edges of the nonwoven web.

In certain types of crosslapper, the input conveyor belt 100 is, in operation, driven with a variable speed and is therefore subject to more or less sudden and repeated accelerations and decelerations. Thanks to the invention, the nonwoven WE web being perfectly maintained pressed against the surface of the conveyor belt 100, it can more easily undergo these changes of speed, without risk of sliding or detachment with respect to the surface of the transport band. This result is more particularly sought after and beneficial in the ascending portion 100a of the conveyor belt 100. Nevertheless, it is also of interest in any application in which a non-woven web (monolayer or multilayer) is transported to the surface of the conveyor belt. a conveyor belt in a transport portion subject to speed variations (acceleration or deceleration), said transport portion being ascending or descending (that is to say, inclined relative to the horizontal) or may instead be horizontal.

More generally, the invention is not limited to an implementation at the input of a crosslapper, but can also be used with any conveyor belt, which allows the conveyance on its surface of a strip of no. -woven, and which has an upward transport portion and / or subjected in operation to changes in speed. Said portion of the conveyor belt which is ascending and / or subject to changes in speed, may be rectilinear (as in the example of the portion 100a illustrated in FIGS. 1 and 2), but may also be wholly or partly curve.

Claims (10)

A method of transporting a nonwoven web (WE) by means of a conveyor belt (100) comprising at least one transport portion (100a) which is ascending and / or which undergoes changes in speed, characterized in which comprises electrostatically charging the web of nonwoven (wE) and / or the conveyor belt (100), so as to adhere the strip of non-woven surface of the conveyor belt in said transporting portion (100a) ascending and / or variable speed. Process according to Claim 1, characterized in that the nonwoven web (WE) and / or the conveyor belt (100) are electrostatically charged over at least the entire width (L) of the nonwoven web ( WE). A method according to claim 1 or 2 characterized in that the angle of inclination (A) of the upward transport portion (100a) varies during transport. Process according to one of Claims 1 to 3, characterized in that the nonwoven web (WE) is multilayered. Process according to one of Claims 1 to 4, characterized in that the nonwoven web (WE) is not consolidated. Method according to one of claims 1 to 5, characterized in that the conveyor belt (100) is part of a crosslapper (1). A set for transporting a nonwoven web (WE), said assembly comprises a conveyor belt (100) comprising at least one transport portion (100a) which is ascending and / or which is subjected to changes of speed , characterized in that it comprises ionisation means (15) which, in operation, electrostatically charge the nonwoven web (WE) and / or the conveyor belt (100) so as to adhere the non-woven web (WE) at the surface of the conveyor belt in said upwardly and / or speedily conveying portion (100a) variable. Transport assembly according to claim 7, characterized in that the ionization means (15) comprise at least one ionizing bar which is mounted above and in proximity to the ascending and / or variable speed transport portion (100a). Transport assembly according to claim 7 or 8, characterized in that the inclination (A) of the ascending conveying portion (100a) is adjustable or variable. Spreader-spreader (1), characterized in that it comprises as input a transport assembly according to one of claims 7 to 9.

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