EP3978661A1 - Screen apron - Google Patents

Abstract

A sieve belt (10) is used to transport a fiber structure (6) to be compressed over a suction slot (9) of a compression device (2) of a spinning machine. It has an endless scope. A multiplicity of adjacent longitudinal filaments (15) are arranged in the circumferential direction (U) and a multiplicity of adjacent transverse filaments (16) are arranged transversely to the circumferential direction (U). There are spacings (AL, AQ) between adjacent longitudinal filaments (15) and adjacent transverse filaments (16), which form free areas so that the sieve apron (10) is air-permeable. The adjacent longitudinal filaments (15) have a thinner cross-section than the transverse filaments (16).

Description

The present invention relates to an endless screen apron for transporting a fiber structure to be compressed over a suction slit of a compression device of a spinning machine, which has a large number of adjacent longitudinal filaments in the circumferential direction and a large number of adjacent transverse filaments transversely to the circumferential direction, with spacings being present between adjacent longitudinal filaments and adjacent transverse filaments , which form free surfaces so that the sieve apron is permeable to air.

A fiber bundle drawn in a drafting system leaves the drafting system with a specific width and is then twisted into a thread with a relatively small diameter. The thread contains marginal fibers that are not properly tied into the twisted thread and thus contribute little at most to the strength of the thread. In order to increase the strength of the yarn, the drafting zone of the drafting system is followed by a compression zone. In the compaction zone, the fibers are compacted relative to one another, which causes the fiber structure to become narrower. The resulting thread then becomes more even, firmer and less hairy.

Among other things, a suction tube, which is surrounded by an endless, air-permeable sieve strap, is used to compress the fiber structure. The sieve apron slides over a suction slot of the suction tube, which is arranged at an angle to the running direction of the fiber structure. The running direction of the fiber structure essentially corresponds to the circumferential direction of the sieve apron. The fiber structure is transported on the sieve apron and compressed along a suction edge of the suction slot.

From the DE 10 104 182 A1 such an air-permeable conveyor belt for transporting a fiber structure to be compressed via a suction slot of a compression zone of a spinning machine is known. The transport belt is designed as a fabric belt and consists of longitudinal threads running in the transport direction of the fiber structure and transverse threads running transversely to the transport direction of the fiber structure. The clear distance between two longitudinal threads is greater than the clear distance between two transverse threads. The aim is to create a conveyor belt which, on the one hand, ensures a sufficiently large air throughput and, on the other hand, prevents loss fibers from being sucked off as far as possible.

The disadvantage of this screen apron is that it wears out relatively quickly in the course of its use. In addition, the mobility of the fibers on the surface of the sieve apron is restricted in the transverse direction. It can therefore be difficult to compress the fiber structure at the suction edge.

The object of the present invention is therefore to create a screen apron that is wear-resistant and still allows the fiber structure on the screen apron to be moved very well transversely to the circumferential direction of the screen apron.

The object is achieved by a sieve strap with the features of patent claim 1.

A sieve apron has an endless circumference for transporting a fiber structure to be compressed over a suction slot of a compression device of a spinning machine. A multiplicity of adjacent longitudinal filaments are arranged in the circumferential direction of the sieve apron and a multiplicity of adjacent transverse filaments are arranged transversely to the circumferential direction of the sieve apron. Between adjacent longitudinal filaments and adjacent transverse filaments there are spaces which form free surfaces, so-called sieve surfaces, so that the sieve apron is permeable to air. These distances can also be called mesh size. According to the invention, the longitudinal filaments have a thinner cross-section than the transverse filaments.

In the screen apron according to the invention, the use of finer longitudinal filaments, which will generally be the weft filaments, and stronger transverse filaments, which will generally be the warp filaments, leads to significant advantages. With the stronger transverse filament, the sieve apron has a larger wear volume. The reason for this is that the stronger transverse filament lying transversely to the circumferential direction of the sieve apron or transversely to the transport direction of the fiber structure rests on the suction pipe, while the longitudinal filament is tensioned in such a way that it is not pressed onto the suction pipe even under the load of a pressure roller. Accordingly, wear occurs first on the thicker transverse filament. This increases possible wear times and extends the service life of the screen apron accordingly. The necessary low flexural rigidity of the sieve apron is also retained with the finer longitudinal filament. The sieve strap continues to run around the small radii of the intake manifold without a gap. Another advantage is that the fibers lie mainly on the backs of the stronger and more closely spaced transverse filaments. As a result, the fibers of the fiber structure can be shifted more easily transversely to the spinning direction and can thus be compressed more intensively. If at all, the fibers are correspondingly less hindered in their transverse movement by the longitudinal filaments because of their greater spacing.

A particular advantage of the invention is that the thinner longitudinal filament touches the suction pipe, if at all, with reduced contact pressure and only after it has reached the transverse filaments after a certain operating time corresponding wear and tear has occurred. A screen apron that consists of both reinforced transverse and reinforced longitudinal filaments could be advantageous in terms of wear, but it would have disadvantages in terms of the transverse displaceability of the fibers and the flexibility of the screen apron in the circumferential direction and thus the lack of gaps between the suction pipe and screen apron be avoided with the screen apron according to the invention.

A particularly advantageous embodiment of the sieve apron is when the longitudinal filaments are arranged within areas formed by turning points of the transverse filaments. A kind of top surface on the screen apron is thus spanned by the transverse filaments. Due to the thinner longitudinal filaments, the fabric can be produced in such a way that the longitudinal filaments, at least when new, are always at most level with the transverse filaments, but preferably below the transverse filaments. Accordingly, the longitudinal filaments are not exposed to the transverse filaments. They are preferably below the transverse filaments, but at most in the same surface area as the transverse filaments. They are thus largely protected from wear and tear by the thicker transverse filaments. As a result, the screen apron remains operational for longer and retains the property of good transverse mobility of the fibers on the screen apron for a long time.

It is advantageous if the longitudinal filaments meander less than the transverse filaments. This can also be referred to as incorporation or crimping. Incorporation is the ratio of the length of a filament incorporated into the fabric to its length in the stretched state. The smaller the incorporation, the more stretched are the filaments in the fabric. In the present case, this means that the particularly advantageous sieve apron has a smaller incorporation of the longitudinal filaments than the transverse filaments. The distance between the turning points of the longitudinal filaments is therefore smaller than the distance between the turning points of the transverse filaments. That Sieve straps are woven with a small weft incorporation when the longitudinal filament is the weft filament. The longitudinal filament or the weft filament only meanders very weakly or, if it runs essentially in a straight line, hardly at all through the transverse filaments or the warp filaments. Minimal meandering is advantageous in order to obtain better resistance to displacement of the fabric.

It is also advantageous if the longitudinal filaments run essentially in a straight line. The longitudinal filaments are therefore not or hardly incorporated into the fabric. The stability of the transverse filaments relative to each other is thus reduced, but the resistance to wear and the ability for the fibers to be very easily moved transversely on the sieve apron is improved as a result. The reason for this is that it takes longer for the transverse filaments to wear down to the same height as the thinner longitudinal filaments, or for the sieve apron to tear.

Furthermore, it is advantageous if the distance between adjacent longitudinal filaments is greater than the distance between adjacent transverse filaments. The close spacing of the transverse filaments is compensated for by the larger spacing of the longitudinal filaments with regard to the mesh size. Conversely, the free screen area does not become too large due to the closer arrangement of the transverse filaments. If the screen surface is too large, the fibers would be increasingly sucked through it. It is therefore advantageous to create a screen surface which, on the one hand, allows the fibers to adhere sufficiently to the screen apron, but on the other hand continues to allow the fibers to be displaced laterally and, if possible, no fibers are sucked through the screen apron.

Accordingly, it is advantageous if the free surface between the longitudinal filaments and the transverse filaments, i.e. the screen surface, is between 20% and 60%, preferably between 30% and 50% of the screen apron area. The suitable size of the screen surface depends in particular on the type and size of the fibers of the fiber assembly to be compressed.

It is also extremely advantageous if the transverse filaments have a diameter that is between 10% and 80% larger than the diameter of the longitudinal filaments. Here, too, the suitable diameter of the filaments depends, among other things, on the type and size of the fibers of the fiber assembly to be compressed. In addition, the service life, i.e. the duration of the wear resistance of the screen apron, and the mobility of the fibers can be influenced as a result.

It is particularly advantageous if the sieve strap has a plain weave or a twill weave. As a result, the screen strap can be easily manufactured. With a plain weave, on the one hand the dimensional stability of the fabric and on the other hand the adaptation to the suction tube without a gap is very good. This creates very good resistance to displacement and running stability. With the twill weave, running directions of the sieve apron or different sides of the sieve apron can be produced.

There are also advantages if the sieve apron has an antistatic finish. This can be done with an antistatic coating of the sieve apron, for example with carbon. However, all or some of the filaments can also be made of antistatic material and woven into the screen strap.

It is particularly advantageous if imaginary surfaces lying on the turning points of the transverse filaments are at a distance from turning points of the longitudinal filaments, as a result of which the thinner longitudinal filaments are arranged at a distance between these surfaces. This creates one Structure on the surface of the apron, which is particularly advantageous for the movement of the fibers during the compression of the sliver.

Figur 1

eine Seitenansicht auf ein Streckwerk einer Spinnmaschine mit einer Verdichtungseinrichtung,

Figur 2

eine Draufsicht auf eine Verdichtungseinrichtung mit einem Siebriemchen,

Figur 3

einen vergrößerten Ausschnitt auf ein Gewebe eines Siebriemchens,

Figur 4a

einen Schnitt durch ein Gewebe eines Siebriemchens in Umfangsrichtung des Siebriemchens und

Figur 4b

einen Schnitt durch ein Gewebe eines Siebriemchens quer zur Umfangsrichtung des Siebriemchens.

Further advantages of the invention are described in the following exemplary embodiments. It shows:

figure 1

a side view of a drafting system of a spinning machine with a compression device,

figure 2

a plan view of a compression device with a screen belt,

figure 3

an enlarged section of a fabric of a sieve strap,

Figure 4a

a section through a fabric of a sieve apron in the circumferential direction of the sieve apron and

Figure 4b

a section through a fabric of a sieve apron transversely to the circumferential direction of the sieve apron.

In the following description of the exemplary embodiments, the same reference symbols are used for features that are identical and/or at least comparable in their design and/or mode of operation. If these are not explained again in detail, their design and/or mode of action corresponds to the design and mode of action of the features already described above.

figure 1 shows a schematic representation of a side view of a section of a drafting system 1 of a spinning machine, in particular a ring spinning machine with a compression device 2. The drafting system 1 comprises a pair of feed rollers 3, a pair of draft rollers 4 and a pair of exit rollers 5. Each of the pairs of rollers 3, 4 and 5 is formed by an upper roller and a lower roller or a lower cylinder. The two rollers of each pair of rollers 3, 4 and 5 are pressed against each other and form at their point of contact a respective nip point K1, K2 and K3 for a fiber structure 6 entering the drafting system 1, with the nip point K1 being held by the pair of draw-in rollers 3 and the nip point K2 being held by the pair of draft rollers 4 and the nip K3 is formed by the output roller pair 5. A thread clamping point K4 is formed by a pressure roller 7 which presses against a suction pipe 8 which can be sucked. Due to the different speeds of the roller pairs 3, 4 and 5, the fiber structure 6 is stretched. During the drafting, the fiber structure 6 is transported through the drafting system 1 at the same time. After leaving the drafting system 1, the drafted sliver 1 reaches the compression device 2, in which it is compressed.

The compression device 2 has a suction slot 9 between the clamping point K3 and the thread clamping point K4 on the suction tube 8, at the edge of which the fibers of the fiber structure 6 are bundled or compressed. The stretched fiber structure 6 is transported in the transport direction T by means of a sieve belt 10, which loops around the suction pipe 8 and a deflection rod 11 in the circumferential direction U, over the suction pipe 8. The screen apron 10 is driven by the pressure roller 7 . The pressure roller 7 is in turn set in rotation by means of elements not shown via the upper roller of the pair of output rollers 5 . Negative pressure, which is present in the suction tube 8 and sucks in the fiber structure 6 via the suction slot 9, also acts through the sieve strap 10, which is permeable to air.

After the compression device 2, the fiber structure 6, which forms a thread 12 after the clamping point K4, reaches a thread guide 13 and is guided on to a spinning device, not shown.

To open the drafting system 1, the upper rollers of the lower rollers of the roller pairs 3, 4 and 5 and the pressure roller 7 can be raised. For this purpose and to close the drafting system 1 again, a loading arm 14, to which the upper rollers and the pressure roller 7 are fastened in a known manner, is moved about a pivot point D in the direction of the arrow P.

figure 2 shows a plan view of the compression device 2 with the sieve apron 10. The fiber structure 6 is transported together with the rotating sieve apron 10 in the circumferential direction U of the sieve apron or in the transport direction T of the fiber structure 6 via the suction pipe 8. The sieve strap 10 rests on the intake manifold 8 and slides over it. The sieve apron 10 is driven, as shown in FIG figure 1 visible, by the in turn driven pressure roller 7. The fiber structure 6 is sucked in in the area of the suction slot 9 and is compressed at an edge of the suction slot 9, which is positioned at an angle with respect to the transport direction T of the fiber structure 6. For this purpose, the sieve apron 10 is air-permeable, so that the negative pressure present in the suction pipe 8 can act through the sieve apron 10 on the fibers of the fiber structure 6 . In particular, due to the sliding contact of the filter apron 10 on the suction pipe 8, wear occurs on the underside of the filter apron 10.

figure 3 shows an enlarged section of a fabric of a sieve apron 10 according to the invention in a plain weave. The fabric of the sieve apron 10 has adjacent longitudinal filaments 15 and adjacent transverse filaments 16 . Fibers 17 of the fiber structure 6 resting on the sieve apron 10 are shown schematically. The fiber structure 6 accordingly lies in the transport direction T of the fiber structure 6 on the sieve apron 10. The fibers 17 are longitudinally aligned in the circumferential direction U of the sieve apron 10 .

Longitudinal filaments 15 and transverse filaments 16 are each spaced apart from one another, so that the sieve apron 10 is permeable to air by means of the resulting meshes. A distance AL between the longitudinal filaments 15 is greater than a distance AQ between the transverse filaments 16. The distance AL can be about 400 μm, for example, and the distance AQ can be 100 μm, for example. A resulting screen surface 18 has between the longitudinal filaments 15 and the transverse filaments 16 rectangular meshes with the dimensions of the distances AL and AQ. Due to the small mesh size in the circumferential direction U or transport direction T, there is less fiber loss. The large mesh width transverse to the fiber direction enables a large volume flow of the suction air and a good compression effect of the fiber structure 6. The free area between the longitudinal filaments 15 and the transverse filaments 16, the screen surface 18, is in particular between 20% and 60%, preferably between 30% and 50% of the total screen apron area.

The longitudinal filaments 15 have a diameter DL which is significantly smaller than a diameter DQ of the transverse filaments 16. The transverse filaments 16 preferably have a diameter DQ which is between 10% and 80% larger than the diameter DL of the longitudinal filaments 15 For example, the transverse filaments 16 can have a diameter DQ of approximately 150 μm and the longitudinal filaments 15 have a diameter DL of approximately 100 μm. This difference in diameter causes the sieve apron 10 to rest on the suction pipe 8 essentially on the surfaces of the transverse filaments 16 . The wear will thus affect the transverse filaments 16 first. Only when this is at a height are worn away so that they are the same as the longitudinal filaments 15, the longitudinal filaments 15 are also included in the wear.

Figure 4a shows a section through a fabric of a sieve apron 10 in the transport direction T of the fiber structure 6 or in the circumferential direction U of the sieve apron 10. The fibers 17 of the fiber structure 6 would accordingly lie on the sieve apron 10 along the plane of the drawing. It can also be seen from this representation that the diameter DL of the longitudinal filaments 15 is smaller than the diameter DQ of the transverse filaments 16. Accordingly, imaginary surfaces F, which rest on turning points WQ of the transverse filaments 16, are at a distance from turning points WL of the longitudinal filaments 15. Accordingly, the Underside of the sieve apron 10 essentially with the turning points WQ of the transverse filaments 16 on the suction pipe 8. On the upper side of the sieve apron 10, the pressure roller 7 essentially also acts on the turning points WQ of the transverse filaments 16. Accordingly, the wear will essentially take place on the transverse filaments 16, since the thinner longitudinal filaments 15, which also meander less, are spaced at a distance a from these surfaces F and thus generally have no contact with the suction pipe 8 and the pressure roller 7. The distance AWL between the turning points WL is therefore less than the distance AWQ between the turning points WQ. The turning points WL lie between the two surfaces F.

In Figure 4b a section through a fabric of a sieve apron 10 is shown transversely to the transport direction T of the fiber structure 6 or transversely to the circumferential direction U of the sieve apron 10 . The fibers 17 of the fiber structure 6 would thus lie perpendicularly to the plane of the screen apron 10 . Also here, as well as in Figure 4a , to recognize that the imaginary surface F resting on the turning points WQ is at a distance a from the turning points WL of the longitudinal filaments 15 . This creates points of attack for the sieve apron 10 to slide over the Suction pipe 8 and for the drive by the pressure roller 7 essentially on the thicker transverse filaments 16. The thinner longitudinal filaments 15 are located on each side of the sieve apron 10 at a distance a from the respective surface F. The thinner longitudinal filaments 15 are thus separated by the thicker transverse filaments 16 protected because they are not arranged exposed to the transverse filaments 16 in the fabric of the sieve apron 10.

From the representation of Figures 4a and 4b it can also be seen that the longitudinal filaments meander less than the transverse filaments. Depending on the embodiment, the meandering can even be largely dispensed with completely. The longitudinal filaments then run completely or at least almost in a straight line.

The present invention is not limited to the illustrated and described embodiments. In particular, thickness and spacing ratios of the longitudinal filaments 15 and transverse filaments 16 other than those shown are possible. The incorporation of the longitudinal filaments 15 can also be more or less than shown in the exemplary embodiments. Despite the different diameters of the longitudinal filaments 15 and transverse filaments 16, it is also possible within the scope of the invention for the distance a to be reduced to the value “0”. This can be brought about by incorporating the longitudinal filaments 15 to a greater extent.

Modifications within the scope of the patent claims are just as possible as a combination of features, even if they are shown and described in different exemplary embodiments.

Reference List

1

drafting system

2

compression device

3

feed roller pair

4

delay roller pair

5

output roller pair

6

fiber bandage

7

pressure roller

8th

intake manifold

9

suction slot

10

sieve straps

11

deflection rod

12

thread

13

thread guide

14

Low-impact

15

longitudinal filaments

16

transverse filaments

17

fibers

18

screen surface

a

distance

AQ

Distance transverse filaments

AL

Distance longitudinal filaments

IL

distance

AWQ

distance

DQ

diameter of transverse filaments

DL

diameter of longitudinal filaments

D

pivot point

f

Surface

K1

clamping point

K2

clamping point

K3

clamping point

K4

thread pinch point

L

running direction

P

arrow direction

WQ

Turning point transverse filaments

WL

Turning point longitudinal filaments

Claims (10)

Sieve aprons for transporting a fiber structure (6) to be compressed over a suction slot (9) of a compression device (2) of a spinning machine, with an endless circumference, which has a large number of adjacent longitudinal filaments (15) in the circumferential direction (U) and one transversely to the circumferential direction (U). has a large number of adjacent transverse filaments (16) and between adjacent longitudinal filaments (15) and adjacent transverse filaments (16) there are spacings (AL, AQ) which form free surfaces so that the sieve apron (10) is air-permeable, characterized in that the adjacent Longitudinal filaments (15) have a thinner cross-section than the adjacent transverse filaments (16). Sieve apron according to the preceding claim, characterized in that the longitudinal filaments (15) are arranged within surfaces (F) formed by turning points (WQ) of the transverse filaments (16). Sieve apron according to one or more of the preceding claims, characterized in that the longitudinal filaments (15) meander less than the transverse filaments (16), as a result of which a distance (AWL) between the turning points (WL) of the longitudinal filaments (15) is less than a distance (AWQ ) of the turning points (WQ) of the transverse filaments (16). Sieve apron according to one or more of the preceding claims, characterized in that the longitudinal filaments (15) run essentially in a straight line. Sieve apron according to one or more of the preceding claims, characterized in that the distance (AL) between adjacent longitudinal filaments (15) is greater than the distance (AQ) between adjacent transverse filaments (16). Sieve apron according to one or more of the preceding claims, characterized in that the free area between the longitudinal filaments (15) and the transverse filaments (16) is between 20% and 60%, preferably between 30% and 50% of the sieve apron area. Sieve apron according to one or more of the preceding claims, characterized in that the transverse filaments (16) have a diameter (DQ) which is between 10% and 80% larger than the diameter (DL) of the longitudinal filaments (15). Sieve apron according to one or more of the preceding claims, characterized in that the sieve apron (10) has a plain weave or a twill weave. Sieve apron according to one or more of the preceding claims, characterized in that the sieve apron (10) has an antistatic finish. Sieve apron according to one or more of the preceding claims, characterized in that imaginary surfaces (F) which lie on the turning points (WQ) of the transverse filaments (16) are spaced apart from the turning points (WL) of the longitudinal filaments (15), whereby the thinner longitudinal filaments (15) are arranged at a distance (a) from these surfaces (F).

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