EP2547812B1 - Drawing frame having a guide table for a guide apron - Google Patents

Description

The invention relates to a drafting system for warping a fiber structure of a workstation of a textile machine with two successively arranged in the transport direction of roller pairs, each containing a drivable lower roller, wherein the first lower roller in the transport direction is associated with a Führungsriemchen that this lower roller and one between the first and the second Sub-roller arranged guide table wraps around.

A drafting system of this kind is from the DE 10 2005 045 876 A1 known. In the known drafting a designated as "deflection" guide table is attached to a fixed frame part of the drafting system. The lower rollers are stored as part of the drafting system. The guide table is changeable in position with respect to the bottom rollers so that the tension of the bottom apron can be adjusted.

In the US 3,055,060 A . DE 44 38 946 A1 such as JP H03 115674 U discloses a bearing carriage, which is displaceable along a linear guide and fixed by means of a screw.

The DE 700 601 C1 discloses a drafting system which is opened in the longitudinal direction of a punch. The guide strap is tensioned with a spring independent of the bearing.

The DE 10 2004 053 505 A1 as well as the next coming DE 39 32 614 A1 Although disclosed a drafting system, the lower rollers are each driven by means of a separately controllable drive, but nothing to the storage of the lower rollers and the tensioning of the Führungsriemchen.

The invention has for its object to improve the drafting and the uniformity of the warped fiber structure.

The object is achieved with the drafting device of the type mentioned above in that the first lower roller is mounted in a bearing slide displaceable in the transport direction and the second lower roller in a bearing block, and that the guide table is fixed to the bearing block of the second lower roller.

The drafting device according to the invention has the advantage that the position of the guide table is fixed with respect to the second lower roller and can not change. In the manufacture of the bearing block for the second lower roller, the position of the guide table can be set with very small tolerances. The Unterriemchen can thereby pass very close to the lower roller.

In high-speed drafting systems, in which in particular the lower roller arranged downstream of the guide belt rotates at a high circumferential speed, a drag flow occurs at this lower roller. The rapidly rotating surface of the lower roller takes air with it by its rotation and conveys it into the region of the draft zone in which the fiber structure emerges from the Riemchenaggregat. This effect is enhanced by the fact that the lower roller usually has a corrugation on its peripheral surface.

So that the lower apron does not touch the much faster moving lower roller and is thereby damaged, only a minimal gap between the surface of the Führungsriemchens and the lower roller surface is necessary, which is advantageously only a few tenths of a millimeter. Due to this small distance, the drag flow generated by the lower roller can be kept as far as possible from the fiber structure.

A worn guide strap must be replaced. The new Führungsriemchen is tense by the fact that the bearing carriage of the first Lower roller is moved with a defined force against the transport direction. The displacement of the bearing carriage can compensate for the manufacturing tolerances of the circumferential length of the Führungsriemchens. The guide table remains in the same position, so that the gap between the new guide apron and the lower roller is again exactly as small as before. This is a significant advantage.

It has surprisingly been found that even small changes in this area lead to a change in the flow conditions in the area between Führungsriemchen and second pair of rollers where the fiber strand is unguided and there may affect the distortion, in particular the uniformity of the warped fiber structure.

It is provided a frame that carries the drafting system. The frame may be a single frame for a single drafting system or a common frame for a plurality of adjacent drafting systems. The bearing block and the bearing carriage are each a component with a receptacle for a bearing for mounting the respective lower roller. The bearing carriage is displaceable along a linear guide, for example a rail. The linear guide is preferably fixed stationarily on the frame. The bearing carriage can be fixed for example with one or more screws on the frame. By assigning the screw a slot or a groove, a displacement possibility of the bearing carriage can be realized. The bearing block is preferably stationary mounted on the frame or integrated into the frame, especially when it is in the bearing block mounted in the lower roller to the output lower roller of the drafting system. Alternatively, however, it may be provided that the position of the bearing block is adjustable together with the guide table with respect to the frame or an air nozzle assembly arranged downstream of the output roller pair. An adjustable position of the bearing block is also advantageous if the lower roller mounted in the bearing block is arranged downstream of a further lower roller. The drafting arrangement according to the invention is a single drafting arrangement which can be driven separately for a single workstation of a textile machine. It is preferred that the first lower roller in the bearing carriage and the second lower roller are mounted in the bearing block flying. The drafting system is particularly suitable for a high-speed spinning machine, for example an air-spinning machine, or a machine for spinning knitting, in which the fiber structure supplied by the drafting system is fed directly to a knitting device.

Between the bearing carriage and the bearing block, a tensioning device for tensioning the Führungsriemchens is arranged. The clamping device can preferably be formed by a pressure spring arranged between the bearing carriage and the bearing block. When changing the Führungsriemchens can thereby easily adjust the desired tension of the Führungsriemchens. The fastenings of the bearing carriage need only be easily solved and the bearing carriage is moved so far by the clamping device that the guide strap has the desired voltage.

In an embodiment of the invention, it is advantageous if the guide table contains an exchangeable element which is exchangeable to adapt the guide geometry of the Führungsriemchens in the draft zone. The guide table advantageously has a receptacle for the replaceable element. The receptacle is preferably U-shaped, T-shaped or dovetailed to ensure good positioning of the replaceable element. The replaceable element may have different geometries that cause an altered Riemchenlauf in the draft zone. As a result, the drafting system can be adapted to the type of fiber structure to be distorted. Different replaceable elements are advantageously designed so that the distance between the Führungsriemchens to the surface of the second lower roller does not change, so that the flow conditions do not change even when replacing the replaceable element.

Further advantages and features of the invention will become apparent from the following description of an embodiment.

Figur 1

eine schematische Seitenansicht eines teilweise dargestellten Doppelriemchen-Streckwerks gemäß der Erfindung,

Figur 2

eine Draufsicht in Richtung des Pfeils II der Figur 1 auf das Streckwerk, wobei die Oberwalzen und das Oberriemchen zur Verdeutlichung weggelassen wurden, und

Figur 3

eine Ansicht in Richtung des Pfeils III der Figur 1, wobei auch hier die Oberwalzen weggelassen wurden.

Show it:

FIG. 1

a schematic side view of a partially illustrated double apron drafting system according to the invention,

FIG. 2

a plan view in the direction of arrow II of FIG. 1 on the drafting system, with the top rollers and the top apron have been omitted for clarity, and

FIG. 3

a view in the direction of arrow III of FIG. 1 , where also the top rollers have been omitted.

In the FIGS. 1 to 3 is a Doppelriemchenstreckwerk 1 shown. The drafting system 1 contains two pairs of rollers 2 and 3, each consisting of a lower and a top roller. The drafting system 1 may comprise further pairs of rollers, not shown, upstream of the roller pair 2 and / or downstream of the roller pair 3. The pair of rollers 2 consists of a bottom roller 4 and a top roller 5. The pair of rollers 3 consists of a bottom roller 6 and a top roller 7, which has a reference from a rubber-elastic material in a conventional manner. The upper rollers 5, 7 are pressed by a loading device, not shown, to the lower rollers 4, 6. The rollers 4, 5 are looped through in each case a Führungsriemchen 8, 9. The Unterriemchen 8 also wraps around a guide table 10. The Oberriemchen 9 is guided by a Oberriemchenkäfig 11. The lower rollers 4, 6 are each connected to a drive 12, 13 and thereby drivable, as in FIG. 2 is indicated schematically.

A fiber structure 14 to be pulled from staple fibers is fed in the transport direction A to the first pair of rollers 2. The second pair of rollers 3 rotates at a substantially higher peripheral speed than the first pair of rollers 2. As a result, the fiber structure 14 is warped to a lower fineness. In the case shown, the fiber structure 14 is completely warped on the nip line 15 of the second pair of rollers 3 and is fed to an air jet unit 16, which gives the fiber structure 14 its spin rotation. The finished yarn is wound after the air jet unit in a manner not shown. The drives 12, 13 are separately controllable, so that delay and delivery speed of the fiber structure 14 can be varied independently of other jobs.

The lower roller 6 generates by its rotation in the direction of arrow B, a drag flow that promotes air in the wedge gap in front of the nip 15. The fiber structure 14 to be distorted is unguided and very sensitive in this area when it has left the guide straps 8, 9 and is not yet held in the nip 15. The guide table 10 is therefore arranged so that the guide belt 8 is guided as close as possible to the surface of the lower roller 6 by its deflection edge 17. The gap 18 between the Führungsriemchen 8 and the lower roller 6 is less than 0.5 mm. The drag flow is largely kept away from the fiber structure 14.

The lower rollers 4 and 6 are both cantilevered. The lower roller 4 is mounted in a bearing carriage 19. The bearing carriage 19 is seated on a punch or a frame 20 of the drafting system 1 and is displaceable in the transport direction A along a linear guide 30. The linear guide 30 is formed by a rail on which the bearing carriage 19 is seated. For fixing the bearing carriage 19, a screw 21 is provided. In the linear guide 30, the screw 21 is associated with a slot or a groove 31. After displacement of the bearing carriage 19 in the desired position of the bearing carriage 19 is fixed by the screw 21. The lower roller 6 is in a bearing block 22 mounted, which is also attached to the frame 20. In the case shown, the second pair of rollers 3, the output roller pair of the drafting system 1, so that a displacement of the bearing block 22 in the transport direction A or adjustability with respect to the frame 20 is not essential.

According to the invention, it is provided that the guide table 10 is fixed to the bearing block 22. This ensures that the gap 18 is as small as possible, but without a contact between Unterriemchen 8 and lower roller 6 takes place. Due to the very high relative speed between bottom roller 6 and guide belt 8, the guide belt 8 would be destroyed extremely quickly if it would touch the bottom roller 6.

The guide table 10 contains an exchangeable element 23 which defines the guide geometry of the guide apron 8 in the zone of distortion and which also contains the deflection edge 17. Depending on the material of the fiber structure 14 to be distorted, it may be advantageous to guide the guide straps 8, 9 and thus the fiber structure 14 along another path through the draft zone between the roller pairs 2 and 3. The guide table includes a U-shaped receptacle 24 for the replaceable element 23. It is ensured that the element 23 can be exchanged for another element with a different guide geometry in a very simple manner and that the new element 23 reliable and safe in its intended Position on the U-shaped receptacle 24 is positioned. When replacing the element 23, it is ensured that the deflection edge 17 whose position defines the size of the gap 18 always has the same distance from the surface of the lower roller 6. The guide geometry in the draft zone can be changed without the risk that the fiber structure 14 is affected before the nip 15 by undefined air currents.

In order to make changing the guide belt 8 necessary from time to time very simple, a tensioning device 25 for tensioning the guide belt 8 is arranged between the bearing carriage 19 and the bearing block 22. The tensioning device 25 preferably consists of a compression spring, which is supported on the bearing block 22 and after a slight release of the screw 21 presses the bearing carriage 19 against the transport direction A, so that the guide strap 8 is tensioned with a defined force. So that no periodically fluctuating displacement movement of the bearing carriage 19 occurs in operation, the bearing carriage 19 is fixed firmly in operation by the screw 21 on the frame 20.

reference numeral

1

drafting system

2

first pair of rollers

3

second pair of rollers

4

first lower roller

5

top roll

6

second lower roller

7

top roll

8th

Guide straps (underpants)

9

Guide straps (top apron)

10

guide table

11

apron cradle

12

drive

13

drive

14

fiber structure

15

clamping line

16

Airjet unit

17

deflecting

18

gap

19

bearing slide

20

frame

21

screw

22

bearing block

23

exchangeable element

24

admission

25

tensioning device

30

linear guide

31

Long hole

A

transport direction

B

Rotation direction lower roller 6

Claims (5)

1. A drafting unit (1) for drafting a fibre strand (14) of a working station of a textile machine comprising two roller pairs (2, 3) arranged one downstream of the other in transport direction (A), each of which comprises a driveable bottom roller (4; 6), wherein a guiding apron (8) is assigned to the first bottom roller (4) in transport direction (A), said guiding apron (8) looping this bottom roller (4) as well as a guiding table (10) which is arranged between the first (4) and second (6) bottom roller, and wherein said drafting unit (1) is a single drafting unit which can be driven separately and the bottom rollers (4; 6) of which can each be driven by means of a separately controllable drive (12; 13), so that the draft and the delivery speed of the fibre strand (14) can be varied independently of other working stations, characterized in that

   - the first bottom roller (4) is supported in a bearing carriage (19) which is movable in transport direction (A) and

   - the second bottom roller (6) is supported in a bearing block (22) and that

   - the guiding table (10) is fixed to the bearing block (22) of the sec ond bottom roller (6) and that

   - between the bearing carriage (19) and the bearing block (22), a tensioning device (25) for tensioning the guiding apron (8) is ar ranged.
2. A drafting unit according to claim 1, characterized in that the first bottom roller (4) is supported in the bearing carriage (19) in an overhung position.
3. A drafting unit according to claim 1 or 2, characterized in that the second bottom roller (6) is supported in the bearing block (22) in an overhung position.
4. A drafting unit according to any one of the claims 1 to 3, characterized in that the guiding table (10) comprises a take-up (24) for a replaceable element (23), which element is exchangeable for the purposes of adaptation of the guiding geometry of the guiding apron (8) in the drafting zone.
5. A drafting unit according to any one of the claims 1 to 4, characterized in that the position of the bearing block (22) together with the guiding table (10) is adjustable in relation to a frame (20) or to an air jet aggregate (16).

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