EP2126165B1

EP2126165B1 - Method and apparatus for drawing and depositing a plurality of fibers to form a non-woven

Info

Publication number: EP2126165B1
Application number: EP08707966A
Authority: EP
Inventors: Henning Rave; Wiley Scott Harris
Original assignee: Oerlikon Textile GmbH and Co KG
Current assignee: Oerlikon Textile GmbH and Co KG
Priority date: 2007-01-31
Filing date: 2008-01-17
Publication date: 2011-03-16
Anticipated expiration: 2028-01-17
Also published as: EP2126165A1; WO2008092749A1; CN101600821A; DE602008005561D1; CN101600821B; ATE502141T1

Abstract

The invention relates to a method and an apparatus for drawing and depositing a plurality of fibers to form a non-woven, in which method the synthetic fibers are guided by means of a drawing unit in the form of a blowing stream for being deposited on a deposit belt. When the blowing stream emerges out of the conveying channel into an open space below the drawing unit, a suction stream caused by a natural suction effect is generated, the blowing stream and the suction stream being guided jointly through a short guidance distance towards a deposit belt for depositing the fibers. In order to prevent the effect of the suction stream from influencing the guidance and deposition of the fibers, the suction stream is generated according to the invention out of the ambient air outside of an ambience influencing the deposition of the fibers. For this purpose, conducting means are provided below the drawing unit for guiding the suction stream generated out of the ambient air.

Description

The invention relates to a method for drawing and depositing a plurality of fibers to form a non-woven according to the preamble of claim 1 and an apparatus for implementing the method according to the preamble of claim 8.
When producing a non-woven web of synthetic fibers, a plurality of extruded filament strands have to be deposited as evenly as possible to form a textile fabric. The filament strands are drawn off using a feed fluid more or less after the extrusion and cool-down processes and are guided to a deposit belt. In order to achieve the highest possible delivery rates and depositing speeds, those methods and apparatuses have proved to be particularly useful in which a drawing unit blows the filament strands into an open system. A method of this type and an apparatus of this type are disclosed by way of example in US 6,183,684 . Here, a drawing unit is used in order to draw off, stretch and deposit the synthetic fibers after their extrusion out of a spinning device. The drawing unit comprises a conveying channel, which has a slot-shaped fiber inlet on its upper side. Shortly below the fiber inlet, several fluid inlets open out into the conveying channel, through which fluid inlets a feed fluid, preferably air having the effect of excess pressure is supplied to the conveying channel. The fiber strands are thus drawn into the conveying channel of the drawing unit and accelerated within the guidance channel and blown out in the form of a blowing stream through the fiber outlet of the conveying channel. At the same time, the fiber strands are stretched and received immediately thereafter by a deposit belt for being deposited thereon. The fibers together with the feed fluid hit the deposit belt in the form of a blowing stream. Due to the open system, the blowing stream, after emerging from the drawing unit, interacts immediately with the incoming ambience.
Suction is thus generated particularly on the lower side of the drawing unit due to the blowing out of the fluid and the fibers. This suction leads directly to the suctioning of ambient air. The suction stream generated combines with the blowing stream and is guided together with the blowing stream along the guidance distance up to the deposit belt.
In the production of non-wovens having relatively low basis weights, it has now been observed particularly in the case of short guidance distances between the drawing unit and the deposit belt, that the suction stream propagates in the ambient air up to the ambience of the deposit belt. However, such air movements within the ambient air can negatively influence the deposition of the non-woven on the deposit belt or optionally also the deposition of the fibers.
In principle, it is possible to prevent such ambient influences by arranging a closed system having guidance shafts immediately downstream of the drawing unit. An apparatus of this type is disclosed by way of example in DE 196 12 142 A1 . In such closed systems, the blowing stream generated through the drawing unit is conveyed immediately out of the conveying channel into a guidance shaft, which guides the blowing stream up to its deposition on the deposit belt. However, the basic disadvantage of such closed systems is that longer stretch zones and thus greater distances must be maintained between the drawing nozzle and the deposit belt due to the guided flow. Thus closed systems are basically suitable only for low and medium production and spinning speeds.
A further method and device for melt spinning fine synthetic fibers to produce a nonwoven material are known from WO 2005/093138 A1 . WO 2005/093138 A1 teaches to extruded a polymer melt through bores of a spinneret to form a fiber strand. The freshly extruded fiber strand is guided together with a gaseous stream through a system of nozzles, such that the fiber strand is split on the outlet side of the nozzle system into several fine fibres. After cooling, the fibers are deposited to form a nonwoven material. To obtain a laminar stream the fibers are guided through an ejector which generates a suction stream.
Document DE 103 22 460 A1 discloses a method and an apparatus for producing a spunbonded fabric of a thermoplastic material, wherein the filaments resulting from broken fibers are additionally tempered and/or drawn and have different diameters and different fiber lengths. The filaments are guided through a channel before they reach a conveyor. Within the channel the filaments are accelerated by a suction stream which is generated by a vacuum source.
Accordingly, it is the object of the invention to provide a method and an apparatus of the generic kind for drawing and depositing a plurality of fibers to form a non-woven in which method or apparatus, the fibers can be guided in a controlled manner through an open space by means of a blowing stream and deposited to form a non-woven.
It is the aim of the invention, in particular, to improve a method and an apparatus of the generic kind such that a uniform and secure production of a non-woven web is possible even at extremely short guidance distances.
This objective is achieved according to the invention by means of a method having the features set forth in claim 1 and an apparatus having the features set forth in claim 8.
Advantageous improvements of the invention are defined by the features and combinations of features of the respective dependent clauses.
The advantage of the invention is that the fibers can be guided up to their deposition substantially without being influenced by the immediate ambience. The suction effect occurring on the outlet side of the drawing unit is used for generating a suction stream, which is generated out of ambient air outside of an ambience influencing the deposition of the fibers, wherein the suction stream is supplied to the blowing stream in the form of two partial suction streams that are sucked in uniformly on both the longitudinal sides of the blowing stream, wherein the partial suction streams are each supplied by means of a lateral suction channel, the ambient air of the partial suction streams being sucked in by means of suction openings of the suction channels and wherein the suction openings of the suction channels are assigned to the ambience laterally next to the drawing unit and turned away from the deposit belt. The immediate ambience within the guidance distance, which is formed by the open space, is thus unaffected by greater exchange flows. Locally limited exchange processes take place only in the boundary area between the blowing stream and the ambience. However, a suction effect that is spread out over greater layers is conveyed in a targeted manner in uncritical areas of the ambience.
For this purpose, the apparatus of the invention comprises at least one conducting means, through which the suction stream generated out of ambient air is supplied from outside of an ambience influencing the deposition of the fibers. Depending on the formation of the conducting means, it is possible to use ambiences that are at a large distance from the deposit belt in order to provide the ambient air required for the suction stream.
The suction stream can be generated preferably on both the longitudinal sides of the blowing stream uniformly so that the suctioned partial suction streams accompany the blowing stream symmetrically and can be used jointly for guiding the fibers.
For this purpose, conducting means are each arranged below the drawing unit on both longitudinal sides of the blowing stream, the conveying means being designed identically for generating equal partial suction streams. It is thus possible to guide every fiber strand within a plurality of fibers with substantially equal conditions through the guidance distance.
In principle, however, it is also possible to variably influence the partial suction streams generated by natural effect on both longitudinal sides by a corresponding formation of the conducting means in order to achieve, for example, special effects when guiding the fibers. It is thus possible to adjust the flow speeds of the partial suction streams variably by changing the suction cross-sections.
The improvement of the invention is particularly advantageous in order to provide ambient air as far as possible out of the nearest ambience for forming the partial suction streams. For this purpose, the partial suction streams are each supplied by means of a lateral suction channel, which has suction openings. It is thus possible to form suction openings facing in any directions by means of the shape of the suction channels.
The suction openings of the suction channels are assigned to the ambience laterally next to the drawing unit and thus turned away from the deposit belt.
According to an advantageous improvement of the invention, for further optimizing the deposition of the fibers on the deposit belt, the blowing stream is shielded from the ambience in at least one depositing area and is absorbed by an exhaust equipment disposed below the deposit belt. For this purpose, on the upper side of the deposit belt there are guidance means provided, which interact with an exhaust equipment disposed below the deposit belt. The blowing stream generated by drawing unit is blown out of the open space into an open guidance channel formed by the guidance means in order to be guided within the guidance channel towards the deposit belt. The guidance means form a spatially limited region above the deposit belt, in which region the fibers are laid to form a non-woven. Surprisingly, it has been seen that the air turbulence generated during the transition of the fiber stream into the open fiber inlet gap does not act negatively on the ambience and thus on the deposition and guidance of the fibers.
In order to generate the least possible turbulence during the transition of the blowing stream out of the open space into the guidance channel, that improvement of the invention has proved to be particularly useful in which a convergent channel opening is assigned to the guidance channel, which channel opening opens out into a channel constriction having a divergent channel outlet towards the deposit belt.
Such an arrangement has proved to be particularly useful in order to achieve a non-woven having uniform strength both in the machine direction and in the cross direction. Due to the relatively high mobility of the fibers within the open space above the guidance means, appropriately large deposit ellipses are generated in the fiber strands, which are restricted in the machine direction just before their deposition on the deposit belt. Thus it is possible to deposit the fibers on the surface of the deposit table so as to achieve the optimum strength and thickness of the non-woven web. For this purpose, the distance between the outlet of the drawing unit and the opening of the guidance channel is preferably larger than half the guidance distance so as to provide the fibers with sufficiently high mobility before they enter into the guidance channel.
It has proved to be particularly advantageous for creating non-wovens having light basis weights if the guidance width of the open space is at least five times larger than that of the constriction of the guidance channel. It is thus possible to achieve a high degree of uniformity even in the case of low fiber densities.
The guidance distance between the blast opening of the drawing unit and the deposit belt can be adjusted to very short distances. The distance between the drawing unit and the deposit belt is preferably formed with a length lying in a range of 100 mm to 700 mm. Thus the desired forms of fiber depositions can be realized depending on the yam count and polymer type and without any influence of the deposition ambience.
According to a preferred refinement of the invention, in order to prevent any exchange processes with the ambience, the open space on the supply side of the belt and on the discharge side of the belt is shielded from the ambience by means of walls. In order to achieve the advantages of the open system in spite of a system that is closed in this manner, the width of the open space formed by the walls is adjusted in a range of 300 and 1,000 mm.
The inventive method and the apparatus of the invention are distinguished by a stable and reproducible deposition of the fibers to form a non-woven web with high uniformity and particularly light basis weight, where both high spinning and production speeds are possible even in the case of the shortest guidance distances in the open system. The invention is used preferably for producing so-called spunbond non-wovens. In principle, however, it is also possible to use the invention for so-called melt-blown non-wovens.
The inventive apparatus and the method of the invention will be described in detail below on the basis of some exemplary embodiments and with reference to the attached figures, in which:

Fig. 1: schematically shows a view of a first exemplary embodiment of the inven- tive apparatus for implementing the method of the invention,
Fig. 2: schematically shows a cross-sectional view of the exemplary embodiment shown in Fig. 1,
Fig. 3: schematically shows a cross-sectional view of another exemplary em- bodiment of the apparatus of the invention.

Fig. 1 and 2 schematically show a first exemplary embodiment of the inventive apparatus for depositing synthetic fiber strands to form a non-woven and for implementing the method of the invention. Fig. 1 shows a side view of the exemplary embodiment while Fig. 2 schematically shows a cross-sectional view thereof. The following description applies to both the figures unless express reference is made to any one of the figures.
The exemplary embodiment shown in Fig. 1 and 2 shows a parallelepiped drawing unit 1, which is usually disposed below a spinning device. Drawing units of this type are known in general and have been explained in detail in the United States Patent Specification US 6,183,684 B1 by way of example. The aforementioned publication may be referred to in this respect; only the essential parts have been included in the following.
The drawing unit 1 comprises a middle conveying channel 5, which is delimited on an upper side of the drawing unit 1 by a slot-shaped fiber inlet 2 and on the lower side of the drawing unit 1 by a blast opening 3. The conveying channel 5 is provided with a slot-shaped design and it extends substantially over the entire length of the parallelepiped drawing unit 1. On the longitudinal sides of the conveying channel 5 there are designed several fluid inlets 27, which are connected to a fluid connection 4. A feed fluid-preferably compressed air-is supplied from a fluid source (not shown) by means of the fluid connection 4, so as to create excess pressure in the conveying channel 5 in relation to the ambience.
The drawing unit 1 is arranged at a distance above a deposit belt 6. The width of the deposit belt 6 extends over the entire length of the drawing unit 1. The deposit belt 6 is preferably guided in the form of an endless belt over several conveyor rollers 28, one of which is shown in Fig. 2, and is driven such that it is directed transversely to the longitudinal side of the drawing unit 1. The deposit belt 6 thus moves continuously in a guidance direction, which is indicated in Fig. 1 and Fig. 2 using arrows. The deposit belt 6 is designed to be permeable to air, an exhaust equipment 22 being disposed on the lower side of the deposit belt 6 in a deposit region formed vertically below the drawing unit 1.
The region between the drawing unit 1 and the deposit belt 6 is used for guiding the fiber strands 20 emerging out of the blast opening 3 in the form of a blowing stream. The distance between the blast opening 3 on the lower side of the drawing unit 1 and the surface of the deposit belt 6 is referred to as the guidance distance here. Directly below the drawing unit 1, there is provided an open space 18, which has a large guidance width with the result that the blowing stream with the fiber strands 20 emerging out of the blast opening 3 can expand freely. Directly below the drawing unit 1, a partial stretch is formed by several conducting means 19 in the open space 18, in which partial stretch a suction stream formed out of the ambient air is supplied to the blowing stream. The conducting means 19 are formed on each side of the drawing unit 1 by suction channels 16.1 and 16.2. The suction channel 16.1 is provided on a belt discharge side 10 and the suction channel 16.2 is provided on the belt supply side 11. The suction channel 16.1 is coupled on the lower side of the drawing unit 1 by means of an outlet opening 15.1 to the blowing stream entering into the open space 18. The opposite end of the suction channel 16.1 comprises a suction opening 17.1, which is connected to the ambience extending above the open space next to the drawing unit 1. For this purpose, the suction opening 17.1 has an opening cross-section, which is turned away from the upper side of the deposit belt 6.
On the opposite longitudinal side of the drawing unit 1, the suction channel 16.2 comprises the outlet opening 15.1 [sic: 15.2] and a suction opening 17.2 in a mirror-symmetrical arrangement. The suction opening 17.2 is likewise coupled to the ambience extending above the open space next to the drawing unit 1. The open space 18 in the area below the drawing unit 1 is thus connected to the ambience by means of the suction channels 16.1 and 16.2. Due to the upwardly directed suction openings 17.1 and 17.2, the ambient air suctioned by the blowing stream is withdrawn in operation from an ambience, which is not critical for depositing the fibers on the deposit belt 6. The suction stream is generated in the form of two equal partial suction streams, which are supplied to the blowing stream on both the longitudinal sides of the fiber curtain by means of the outlet openings 15.1 and 15.2. Thus it is also possible to select very short guidance distances between the drawing unit 1 and the deposit belt 6 for producing fine and light non-wovens.
The open space 18 extends over a length, which exceeds at least half of the guidance distance. In this respect, the blowing stream expands increasingly with its progressive motion with the result that a correspondingly large mobility of the fiber strands is achieved both in the running direction of the deposit belt - also referred to as the machine direction and also in a cross direction thereto.
In the further course of the guidance distance, the open space 18 is delimited by the guidance means 7.1 and 7.2, which are assigned to the upper side of the deposit belt. The guidance means 7.1 and 7.2 are disposed on the belt discharge side 10 and on the belt supply side 11 respectively and form a guidance channel 9 between themselves. The guidance channel 9 extends up to the upper side of the deposit belt 6. In this exemplary embodiment, the guidance channel 9 formed by the guidance means 7.1 and 7.2 is used in order to guide the blowing stream emerging out of the open space 18 by means of the guidance channel 9 for being deposited on the deposit belt 6. For this purpose, the guidance channel 9 is divided into several sections, in order to enable both the entrance and the guidance of the blowing stream. At the end of the open space 18, the guidance means 7.1 and 7.2 initially form a channel opening 8, which opens out convergently into a channel constriction 31. The channel constriction 31 represents the smallest guidance width inside the guidance channel 9. The channel constriction 31 gives way to a divergent channel outlet 32 with the result that the blowing stream, after its initial constriction, expands again due to a constant expansion of the channel constriction. At the end of the guidance channel 9, the fiber strands 20 are deposited on the deposit belt 6.
The guidance means 7.1 and 7.2 are each formed by a pivoted roller 12.1 and 12.2 in this exemplary embodiment. The rollers 12.1 and 12.2 are in direct frictional contact with the deposit belt 6 or the surface of the non-woven 21 in order to effect a seal in relation to the external air. The deposit region representing the end of the guidance channel 9 is thus shielded tightly from the ambience by each of the rollers 12.1 and 12.2. The rollers 12.1 and 12.2 preferably comprise an elastic roller jacket 13 for this purpose.
For implementing and supporting the fiber deposition for forming the non-woven web, the exhaust equipment 22 is disposed on the lower side of the deposit belt 6. The exhaust effect of the exhaust equipment 22 is limited to the deposit region of the guidance channel 9. The exhaust equipment 22 comprises an adjustable exhaust opening 23, which is assigned directly to the deposit region on the deposit belt 6. The exhaust opening 23 is formed between two mobile cover plates 24.1 and 24.2. Each of the cover plates 24.1 and 24.2 can be moved horizontally relative to one another. For sealing the exhaust opening 23, sealing elements 25 are provided on the lower side of the deposit belt 6 so as to prevent external air from entering from the lower side of the deposit belt 6.
During operation, a feed fluid is supplied to the drawing unit 1. Compressed air of a compressed air source is used preferably as the feed fluid, which flows into the conveying channel with an excess pressure lying in the range of 0.1 to 5 bar and preferably in a range of 0.5 to 3 bar. Thus the fiber strands 20 that are threaded into the conveying channel 5 by means of the fiber inlet 2 are continuously drawn off out of a spinning device (not shown). The fibers are previously melt-spun from a polymer material in a row-shaped arrangement in the spinning device and then cooled. Within the conveying channel, the fiber strands 20 are accelerated by the feed fluid and blown out jointly through the blast opening 3 in the form of a blowing stream into the open space 18. The blowing stream, which is composed of the fibers and the feed fluid, is blown vertically through the blast opening 3 towards the deposit belt 6.
On the lower side of the drawing unit 1, a low pressure is generated by the emerging blowing stream, which low pressure leads to the formation of a suction stream. The suction streams are each supplied to the blowing stream on both sides thereof in the form of a partial suction stream. For this purpose, the open space 18 on the lower side of the drawing unit 1 is connected by means of the outlet openings 15.1 and 15.2, the suction channel 16.1 and 16.2, and the suction openings 17.1 and 17.2 to the ambience located at a distance from the ambience of the deposit belt 6. For this purpose, the suction openings 17.1 and 17.2 are formed at an inclination to the drawing unit 1 so that the ambience above the open space 18 laterally next to the drawing unit 1 is used in order to generate the ambient air for forming the partial suction streams on both longitudinal sides of the blowing stream. The ambience directly below the suction channels 16.1 and 16.2 thus remains uninfluenced by the suction stream.
After its passage through the open space 18, the blowing stream with the fiber strands 20 is blown into the guidance channel 9 formed by the guidance means 7.1 and 7.2. Due to the shape and design of the guidance channel 9 and the guidance means 7.1 and 7.2, the blowing stream is guided towards the deposit belt 6. The channel constriction 31 formed in the guidance channel 9 brings about a narrowing of the blowing stream in order to then achieve the desired deposition form of the fibers on the deposit belt 6 by means of a divergent channel outlet 32. It has proved to be particularly advantageous here that the guidance width of the open space 18 is at least 5 times larger than the width of the channel constriction 31. It is thus possible to achieve, in particular, the desired effects for restricting the blowing stream. The repeat expansion of the guidance channel 9, immediately after the channel constriction 31, by means of a divergent channel outlet 32 enables the uniform distribution of the fiber strands inside the blowing stream hitting the deposit belt 6. It has been seen that the deposits of the fiber strands thus generated resulted in a non-woven web, which exhibited high strengths in the machine direction and in the cross direction and a high degree of uniformity in the mass distribution. It was also determined that there is a constant strength in the machine direction and the cross direction of the non-woven, particularly in the case of non-wovens having relatively low basis weights.
In the exemplary embodiment shown in Fig. 1 and 2, particularly good results were achieved in the deposition of the fiber strands and formation of non-woven webs for guidance distances, whose length lies in the range of 100 mm to max. 700 mm. Here, in the lower region of the guidance distance, the channel constriction 31 of the guidance channel 9 is designed with a guidance width in the range of 10 mm to max. 200 mm. In contrast, the open space 18 is designed with a guidance width in the range of 300 mm to 1,000 mm.
The inventive apparatus and the method of the invention thus enable a uniform and reproducible deposition of non-wovens, which can take place such that they can be controlled even at high fiber speeds, fine fiber deniers and light basis weights of the non-woven. Here, firstly the advantages of high stretching known from the process of blowing out the blowing stream into the open space and those depositing mechanisms that are known per se only in closed systems are combined advantageously.
Fig. 3 schematically shows a cross-sectional view of another exemplary embodiment of the inventive apparatus for implementing the method of the invention. The exemplary embodiment shown in Fig. 3 is substantially identical to the previously described embodiment shown in fig. 1 and 2. Hence only the differences therebetween are explained below and reference may be made to the previous description in all other respects.
In the exemplary embodiment shown in Fig. 3, the drawing unit 1 is designed to be identical to the one of the previous exemplary embodiment. Air boxes 34.1 and 34.2 are each connected on the longitudinal sides of the drawing unit 1 on the lower side thereof. The air box 34.1 is disposed on the belt discharge side 10 and an outlet opening 15.1 extending substantially over the entire width of the fiber strands is connected to the open space 18 formed below the drawing unit 1. On the opposite side, a suction channel 16.1 opens out into the air box 34.1, which suction channel forms a suction opening 17.1 at a free end thereof. The suction opening 17.1 is formed on that side of the suction channel that is turned away from the deposit belt 6 and is directed towards the ambience extending laterally next to the drawing unit 1.
On the opposing belt supply side 11, an air box 34.2 with the outlet opening 15.2 and the suction channel 16.2 are formed mirror-symmetrically to the air box 34.1 so as to generate a uniform and identical partial suction stream on each longitudinal side of the blowing stream, which partial suction streams enter the open space 18 together with the blowing stream for guiding the fiber strands 20.
Directly below the air boxes 34.1 and 34.2, the open space 18 is shielded from the ambience by laterally running separation walls 14.1 and 14.2. The separation walls 14.1 and 14.2 extend towards the deposit belt 6 up to the guidance means 7.1 and 7.2. The open space 18 formed by the separation walls 14.1 and 14.2 has a guidance width located in the range of 300 mm and 1,000 mm.
For designing the deposit region, the guidance means 7.1 and 7.2 are formed by molded thin sheets 26.1 and 26.2 on the upper side of the deposit belt 6. The shape of the guidance channel 9 is selected by means of the curvature of the thin sheets 26.1 and 26.2 in such a way that a convergent channel opening 8 opens out into a channel constriction 31 at the end of the open space 18. The channel constriction 31 gives way to an expansion, which leads to a divergent channel outlet 32. On their sides facing the deposit belt 6, the thin sheets 26.1 and 26.2 each have oblong legs 30.1 and 30.2, which extend parallel to the deposit belt 6 and form a sealing gap 29.1 and 29.2 with the deposit belt 6 or with the non-woven web 21. The length of the sealing gap 29.1 and 29.2 is selected such that the deposit region is completely shielded inside the guidance channel 9 on the deposit belt 6. Any frictional contact between the guidance means 7.1 and 7.2 with the non-woven web 21 or the deposit belt 6 is thus prevented on the upper side of the deposit belt.
The exhaust equipment 22 provided on the lower side of the deposit belt likewise has oblong sealing lips 35.1 and 35.2 in order to prevent the entry of external air from the ambience.
The functioning of the apparatus shown in Fig. 3 is substantially identical to that of the exemplary embodiment shown in Fig. 1 and 2. For generating the suction stream, the air boxes 34.1 and 34.2 are disposed on both the longitudinal sides of the blowing stream, through which air boxes an ambient air is sucked in. The ambient air stored in the air boxes 34.1 and 34.2 is withdrawn by means of the suction channels 16.1 and 16.2 and the suction openings 17.1 and 17.2 directly from an ambience that is not relevant to the deposition of the fiber strands. The suction channels can be designed in a tubular manner. It is likewise possible to assign several suction channels to each of the air boxes 34.1 and 34.2. In order to achieve a uniform suction stream acting on the blowing stream, the outlet openings 15.1 and 15.2 of the air boxes 34.1 and 34.2 extend substantially parallel to the width of the conveying channel 5 of the drawing unit 1.
The structure and arrangement of the components of the exemplary embodiments, shown in Fig. 1 to Fig. 3, of the inventive apparatus for implementing the inventive method are illustrated by way of example. It is essential here that conducting means be provided below the drawing unit, which conducting means influence the suctioning of ambient air in such a way that there results no suction stream that could adversely affect the guidance and deposition of the fibers. In the case of very short guidance distances, it is also possible to assign the guidance means on the upper side of the deposit belt to the conducting means and thus, for example, to the air channels or the air boxes. It is likewise possible to guide the blowing stream towards the deposit belt without any guidance means.

List of reference numerals

1: Drawing unit
2: Fiber inlet
3: Blast opening
4: Fluid connection
5: Conveying channel
6: Deposit belt
7.1, 7.2: Guidance means
8: Channel opening
9: Guidance channel
10: Belt discharge side
11: Belt supply side
12.1, 12.2: Roller
13: Roller jacket
14.1, 14.2: Separation wall
15.1, 15.2: Outlet opening
16.1, 16.2: Suction channel
17.1, 17.2: Suction openings
18: Open space
19: Conducting means
20: Fiber strands
21: Non-woven web
22: Exhaust equipment
23: Exhaust opening
24.1,24.2: Cover plate
25: Sealing element
26.1, 26.2: Thin sheet
27: Fluid inlet
28: Conveyor roller
29.1,29.2: Sealing gap
30.1,30.2: Leg
31: Channel constriction
32: Channel outlet
34.1,34.2: Air box
35.1,35.2: Sealing lips

Claims

Method for drawing and depositing a plurality of fibers to form a non-woven, in which method the fibers are drawn off in a row by means of a feed fluid after the melt-spinning, the feed fluid and the fibers being blown in the form of a blowing stream out of a conveying channel into an open space, the blowing stream generating a suction stream caused by a natural suction effect, when the blowing stream emerges from the conveying channel into the open space, and the blowing stream and the suction stream being guided jointly through a short guidance distance to a deposit belt for depositing the fibers,
said method being characterized in that
the suction stream is generated out of the ambient air from above the open space and outside of an ambience influencing the deposition of the fibers, wherein the suction stream is supplied to the blowing stream in the form of two partial suction streams that are sucked in uniformly on both the longitudinal sides of the blowing stream, wherein the partial suction streams are each supplied by means of a lateral suction channel, the ambient air of the partial suction streams being sucked in by means of suction openings of the suction channels and wherein the suction openings of the suction channels are assigned to the ambience laterally next to the drawing unit and turned away from the deposit belt.
Method according to claim 1,
characterized in that
the blowing stream is shielded from the ambience in at least in one deposit region and is absorbed and discharged by an exhaust equipment disposed below the deposit belt.
Method according to claim 1 or 2,
characterized in that
the blowing stream is shielded within the open space from the ambience, the suction stream being supplied only in the blast ambience of the fibers.
Method according to one of the claims 1 to 3,
characterized in that
before being deposited, the blowing stream with the fibers is discharged into a guidance channel, which takes over the guidance of the blowing stream with the fibers up to their deposition on an upper side of the deposit belt.
Method according to claim 4
characterized in that
the blowing stream is guided through a convergent channel opening in the transition between the open space and the guidance channel and is guided through a divergent channel outlet towards the deposit belt after its passage through a channel constriction.
Apparatus for implementing the method according to one of the claims 1 to 7 with a drawing unit (1), which is disposed below a spinning device and a conveying channel (5) connected to a fluid source for receiving the fibers (20) that are guided in a row, a deposit belt (6), which is disposed below the drawing unit (1) and which is driven such that it is directed transversely to a longitudinal side of the drawing unit (1), and a short guidance distance formed between the drawing unit and the deposit belt (6), a blowing stream that is generated by the drawing unit (1) creating a suction stream caused by a natural suction effect when the blowing stream emerges out of the conveying channel (5) into an open space (18), said apparatus being characterized by at least one conducting means (19) below the drawing unit (1) for supplying the suction stream generated out of the ambient air from above the open space (18) and outside of an ambience influencing the deposition of the fibers (20), wherein the conducting means (19) are each disposed below the drawing unit (1) on both the longitudinal sides of the blowing stream and that the conducting means (19) are formed identically for generating equal partial suction streams, wherein the conducting means (19) are formed by two suction channels (16.1, 16.2) directly below the drawing unit (1), the suction channels (16.1, 16.2) being connected by means of outlet openings (15.1, 15.2) to the open space (18) below the drawing unit (1) and by means of suction openings (17.1, 17.2) to the ambience and wherein the suction openings (17.1, 17.2) of the suction channels (16.1, 16.2) are assigned to the ambience laterally next to the drawing unit (1) and thus turned away from the deposit belt (6).
Apparatus according to claim 6,
characterized in that
the suction openings (17.1, 17.2) of the suction channels (16.1, 16.2) are assigned to the ambience laterally next to the drawing unit (1) such that they are turned away from the deposit belt (6).
Apparatus according to claim 6 or 7,
characterized in that
several guidance means (7.1, 7.2) are assigned to the deposit belt (6) on an upper side thereof and an exhaust equipment (22) is assigned to the deposit belt on the lower side thereof, the guidance means and the exhaust equipment forming a shielded deposit region.
Apparatus according to claim 8,
characterized in that
below the deposit belt (6), a displaceable suction opening (23) is formed, by means of which the exhaust equipment (22) is connected to the lower side of the deposit belt (6).
Apparatus according to claim 8 or 9,
characterized in that
the guidance means (7.1, 7.2) form a guidance channel (9) for receiving and guiding the blowing stream, a channel opening (8) of the guidance channel (9) being formed convergently by the guidance means (7.1, 7.2) and the channel opening (8) opening out into a channel constriction (31) of the guidance channel (9).
Apparatus according to claim 9,
characterized in that
the guidance width of the open space (18) is at least five times larger than the width of the channel constriction (31) of the guidance channel (9).
Apparatus according to one of the claims 6 to 10,
characterized in that
the length of the guidance distance between the drawing unit (1) and the deposit belt (6) is in the range of 100 mm to 700 mm.
Apparatus according to one of the claims 6 to 11,
characterized in that
the open space (16) [sic: 18] on a belt supply side (11) and on a belt discharge side (10) is shielded from the ambience by walls (14.1, 14.2).