WO2008071170A1 - Drawing frame for refining fibre material, and apron which is suitable for this purpose - Google Patents

Abstract

A drawing frame for refining fibre material is described, which drawing frame comprises at least one first apron assembly having a roll (4b), at least one deflection element (5b) which is arranged at a spacing from the former and has a deflection face, and a first apron (6b) which is laid over the roll (4b) and the deflection face. According to the invention, the deflection element (5b) has a radius of curvature of less than 2 mm in the region of the deflection face (21b) and the apron (6b) has a thickness (d) of at most 0.7 mm.

Description

 Drafting system for refining fiber material and suitable strapping

The invention relates to a drafting system according to the preamble of claim 1 and a suitable strap.

Draw frames of this type, which are generally referred to as Riemchen drafting systems, include u. a. two pairs of drafting device organs, which are arranged one behind the other in the transport direction of a fiber material to be refined and form a main draft zone. While the drafting of the front in the transport direction pair usually consist of one roller, the rear in the transport direction of each pair of a roller, a first, with distance arranged in front of this roller, also referred to as turning rail deflecting and one to the roller and the Formed straps, wherein the lower apron (also known as Unterriemchen) od at least a second, for tensioning the strap certain deflecting element in the form of a tensioning bow. The like. Is assigned. In addition, the roller of the Unterriemchens and thereby also the Unterriemchen itself is driven. On the other hand, the other upper apron (also called upper apron) is pressed by means of a pressure arm or the like against the lower apron and is dragged by it or by the fiber material guided between the two aprons by friction. Therefore, the lower drafting member of the rear pair can be referred to as a driving, the associated upper drafting organ organ, however, as a driven drafting device organ. In other words, the lower, driven by the lower roller Unterriemchen is pulled over the associated turning rail and therefore claimed to train, while the Oberriemchen pushed by the upper roller substantially only over the associated turning rail, d. H. is claimed to thrust.

The straps used for the described drafting systems usually consist of a middle layer of fabric and two of these adjacent outer layers of rubber. Alternatively, however, single-layer straps made of plastic, in particular polyurethane are known. The thickness of these straps is generally between 0.9 mm and 1.1 mm. However, aprons with thicknesses down to 0.5 mm have also become known (eg DE 10 2004 023 896 A1, DD 296 317 A5, FR 20 57 592 A5). Due to the construction described, a Riemchenstreckwerk has several undesirable properties.

For example, due to the pushing action of the driven upper roller and the narrow deflection radius in the region of the turning rail, the upper apron is deformed in the shape of a funnel or with the formation of a bulge and lifted in a balloon-like manner over an undefined distance from the lower apron. As a result, the fiber quality is significantly impaired, especially in the main draft zone, especially as the deformation or bulging of the top apron is subject to fluctuations.

10

Further, the thrust effect, in particular in the region of the turning rail of the upper apron, has the disadvantageous consequence that the apron at the deflection point is subjected to a rolling process in addition to a friction process. As a result, a warming occurs at least the upper apron, which in high-performance drafting systems

15 60 ⁰ C and more, which is associated with a considerable loss of energy. Although this undesirable effect could be reduced by the use of turning rails and clamps in the form of rotatable rollers, but is dispensed with such roles for cost reasons. Instead, the length of the top apron is usually set with a slight oversize compared to the envelope defined by the strap-carrying peripheral portions of the driven roller and associated turn bar. As a result, however, the deformation of the upper apron caused by the pushing effect is rather increased than reduced, so that no advantages are achieved by this measure in view of the primarily intended uniformity of the fiber transport in the main draft zone. 5

Finally, the conventionally provided by the used Riem- chenmaterial Umlenkradien the turning rails require a certain minimum distance between the exit slit of the two straps and the nip of the following in the transport direction pair of draw rolls, ie the exit slit of the 0 straps can not be so deep in the Eingangszwickel this Stretching rollers are laid, as it would be desirable to equalize the delay. As a result, a friction field is formed between the exit slit of the straps and the nip line of the following pair of rollers, causing the flooding fiber material to transversal vibrations stimulates, which is thereby subjected to uncontrolled fluctuations in its extent. This in turn has the consequence that sometimes more and sometimes fewer fibers are detected by the nip line of the subsequent draw roller pair and an uneven fiber material is obtained. These transversal oscillations and not, as is erroneously assumed by the experts, so-called "floating fibers" are the actual reason why a setting of a apron drafting system leading to a sufficiently uniform fibrous material is often difficult and has to be repeated several times.

The effects described make comparatively little noticeable in drafting systems for conventional ring spinning, because the apron speeds in this case are small and, depending on the desired distortion, amount to about 0.5 cm / s to at most 2 cm / s. In drafting systems for unconventional spinning, which includes the so-called "spinning knitting" is to count (eg PCT WO2004 / 079068), make these effects because of the considerably higher Riemchengeschwindigkeiten of z. B.

10 m / s and more so noticeable that improvements in this regard are urgently needed.

Proceeding from this, the technical problem to be solved by the invention is to design the drafting system of the generic type such that the bulging and swaging of the upper apron are reduced and the exit slit of the two aprons are arranged lower than previously in the gusset of the following pair of drafting system members can.

To solve this problem serve the characterizing features of claims 1 and 14th

The invention is based on the surprising finding that a major reason for the previously existing difficulties in the thickness of the straps used, in particular the Oberriemchen and the relatively large radii of curvature of the associated deflection surfaces of the turning rails can be seen, especially when high Riemchengeschwindigkeiten are desired or required , Characterized in that according to the invention lies at the lower limit of conventional Riemchendicken or even significantly smaller Riemchendicken down to 0, 1 mm are proposed, turning rails can be provided which have deflection surfaces with much smaller radii of curvature. This makes it possible to bring the exit slit of the pair of straps close to the nip line of the subsequent pair of stretching rollers and to largely avoid the described transversal oscillations and their undesired consequences. In addition, it allows the small thickness of Oberriemchens to avoid the previously provided dead state and run the upper apron even with the use of high Riemchengeschwindigkeiten with a certain bias on the associated roller and turning rail. This not only substantially reduces the flexing of the upper strap in the area of the turning bar but, above all, almost completely prevents the formation of a bulge in the area in which the upper strap is pressed against the lower strap.

Further advantageous features of the invention will become apparent from the dependent claims.

The invention will be explained in more detail below in connection with the accompanying drawings of exemplary embodiments. Show it:

Figure 1 shows schematically in a partially sectioned side view of a conventional drafting system for the refinement of fiber material.

Fig. 2 is a provided with a Oberriemchen drafting device of the drafting system of FIG. 1;

Fig. 3 is an enlarged schematic representation of the drafting system of Figure 1 in the transition region from the straps to a subsequent pair of draw rolls.

Fig. 4 increases the deflection of a strap in the region of a deflection element of the drafting system of FIG. 1;

5 shows a cross section through a conventional straps for the drafting system of FIG. 1.

Fig. 6 is a cross section through a on the same scale as in Fig. 5 shown strapping according to the invention;

FIG. 7 shows a representation similar to FIG. 3 when a pair of straps according to the invention is used; FIG. and

8 to 18 cross sections through inventively formed straps and pair of straps for a drafting system according to FIG. 1.

Fig. 1 shows a classic drafting system, the z. B. for processing short fibers and in a direction indicated by arrows 1 transport direction promotes only schematically illustrated fiber material 2. For this purpose, the drafting system has three pairs I, II and III of drafting device bodies arranged one behind the other in the transport direction.

The first pair I includes two rollers 3a and 3b as drafting devices.

The second pair II contains as drafting devices per a roller 4a and 4b, depending in the transport direction in front of this roller 4a, 4b lying, also referred to as turning rail, consisting mostly of a stationary rod deflecting 5a and 5b and one each via the associated rollers 4a, 4b and deflecting elements 5a, 5b guided strap 6a and 6b. The straps 6a, 6b serve the purpose of guiding the fiber material 2 after leaving the rollers 4a, 4b up to an outlet gap 7, which usually has an adjustable jaw width. The strap 6a is also passed over a tensioning element 8 to hold it with a desired preload on the roller 4a and the deflecting element 5a.

The third pair III contains analogously to the first pair I two rollers 9a and 9b as drafting device.

The described rollers 3, 4 and 9 of the three pairs I, II and III of drafting device form between them usual nip lines. Moreover, the pairs I and II form a Vorverzugszone by the peripheral speeds of the rollers 3 and 4 z. B. are selected so that a distortion of the fiber material 2 between 5 and 15 times is obtained. In contrast, the fiber material 2 between the pairs II and III one Main distortion subjected to an extension of the fiber material 2 z. B. by 50 times or more and thereby leads to a desired final fineness at the exit of the roller 9.

The rollers 3a, 4a and 9a are forcibly driven in a conventional manner. Serve not shown, mounted on their shafts gears od. Like. And coupled with these drive motors. In contrast, the rollers 3b, 4b and 9b are taken only by friction of the rollers 3a, 4a and 9a by od as usual on a pressure arm, not shown. Like. Are rotatably mounted, which by means of a force, for. As a spring force, in the direction of the apparent from Fig. 1 arrows F against the rollers 3a, 4a and 9a is pressed. The deflecting element 5b is also mounted on the same pressure arm so that it and thus a lower run 10a (FIGS. 2 and 3) of the strap 6b are pressed against an upper run IIa of the strap 6a. For this purpose, the deflection element 5b may be a component of a conventional, schematically indicated Riemchenkä- figs 12 (Fig. 1).

Due to the apparent from Fig. 1 arrangement forcibly driven, d. H. the driving rollers 3a, 4a and 9a are mostly called lower rollers and the driven by friction, driven rollers 3b and 4b and 9b referred to as top rollers. Accordingly, the strap 6a is a bottom strap and the strap 6b is a top strap. As a result, the same terms are used in the following description, although in principle, the driving drafting organs above and the driven drafting device organs could be down.

As particularly shown in Fig. 2, the lower run 10a of the top apron 6b is deformed in the area between the roll 4b and the deflecting element 5b in the manner described above and provided with a bulge 14 so as not to interfere with the lower run IIa of the Unterriemchens 6a can cooperate. Furthermore, FIG. 3 shows that the deflection of the straps 6a, 6b takes place at a comparatively large distance from the nip line of the rollers of the third pair III. In other words, the exit slit 7 of the pair of aprons reaches very little into a gusset 15 (see also Fig. 1) which is present at the entrance of the rollers 9a, 9b, whereby in the fiber material 2 a friction field indicated by lines 16 which is greatest at a position close to the nip line of the rollers 9a, 9b (reference numeral 18) and from there steadily decreasing in the direction of the flooding fibrous material 2, which is exaggerated in FIG. This changing (pulsating) friction field 16, 18 is the cause of the above-described in Figure 3 by arrows 19 indicated transverse vibrations in the fiber material 2 and the non-uniform fiber feed through the rollers 9a and 9b.

Finally, FIG. 4 indicates that the straps 6a, 6b in the region of the respective deflecting elements 5a, 5b are not only subject to friction but also to flexing, to which reference has been made above.

Draw frames of the type described are well known and therefore need not be explained to the person skilled in the art.

According to the invention, the described and other problems of known drafting systems are avoided in that at least the thickness of Oberriemchen 6b is chosen to be considerably smaller than usual, and the Oberriemchen 6b leading part of the deflector 5b is given a significantly smaller radius of curvature than before. is common.

In Fig. 5 and 6 it is shown that an inventive strap 6 has at most a thickness d (Fig. 6), the z. B. is only about 0.5 to 0.6 times the thickness D (Fig. 5) of conventional straps. It does not matter if the strap 6 is single-layered and z. B. consists of polyurethane or has multiple layers and z. B. is made of two outer rubber layers 20a, 20b and an embedded between these fabric layer 20c. In absolute terms, the apron 6 according to the invention is given a thickness d of at most 0.7 mm and preferably more than 0.1 mm, although the lower limit depends mainly on what is technically feasible. According to current knowledge, also straps 6 with a thickness d of less than 0.1 mm can be used for the purposes of the invention. To date, straps 6 made of polyurethane with values d which satisfy the inequality 0.2 mm <d <0.6 mm have proven to be the best. By choosing Oberriemchen 6b with these thicknesses d is achieved that the radius of curvature of the actual deflection of Oberriemchens 6b causing deflecting surface 21b (Fig. 4) of the respective deflecting element 5b (Fig. 1) substantially smaller than previously selected and z. B. can be set to less than 2 mm. Curvature radii of 0.5 mm to 1.5 mm have proven best to date. This makes it possible to arrange the upper apron 6b (FIG. 1) likewise with a certain pretension by correspondingly increasing the distance between the upper roller 4b and the deflecting element 5b or by providing an additional tensioning element, preferably designed as a rotatable roller, around the upper apron 6b on its entire length to train rather than previously to claim thrust. As a result, not only the flexing of the top apron 6b in the area of the deflection surface 21b is substantially reduced, but also the formation of the bulge 14 (FIG. 2) is effectively avoided.

With particular advantage, the lower apron 6a is also produced with a thickness corresponding to the thickness d of the upper apron 6b according to the invention, and, as particularly shown in FIG. 7, forming both deflecting elements 5a, 5b in the manner of knives or sharp edges, at least in the region of their deflecting surfaces 21a, 21b , d. H. to be provided with very small deflection radii. The two deflection surfaces 21a, 21b can then be placed very deeply in the gusset 15 of the following pair of rollers 9a, 9b, in particular if, in addition, the jaw width is selected to be small. This is possible in particular when the two outermost tips or deflection surfaces 21a, 21b of the two deflection elements 5a, 5b are arranged offset relative to one another in the transport direction (arrows 1), as can be seen from FIG. By this measure, the variable, leading to transversal oscillations part of the friction field (16, 18 in Fig. 3) is very much shortened with the result that the fiber material 2 at the output of the rollers 9a, 9b of the third pair III a fluctuating only to a small extent Quality possesses. Finally, it is not irrelevant that the reduction of the belt thickness due to the reduced flexing leads to a considerable reduction of the energy consumption, especially in high-speed high-speed drafting systems, since the straps 6a, 6b are heated less strongly in the region of the deflection surfaces 21a, 21b.

Further improvements with regard to the described problems can be achieved by preferred constructive embodiments of the straps 6a, 6b, as follows will be explained with reference to FIGS. 8 to 18.

Fig. 8 shows that the Unterriemchen 6a on a the fiber material 2 facing (here upper) side, in contrast to previous practice no smooth, but a roughened surface 23 has. This arises z. B. in that a made of poly-urethane, initially thicker apron material with conventional abrasives, eg. As a usual for the metal grinding grinding wheel and water additive, is ground to the thickness of the invention. The thus no longer smooth, but a certain surface roughness having surface 23 promotes the holding and driving the fiber material 2 during transport, especially when according to Fig. 9 both straps 6a, 6b are roughened on their facing, fiber-carrying sides.

The Unterriemchen 6a of FIG. 10 is provided on its opposite surface 24, which leads no fiber material and facing away from the fiber-carrying surface 23, with at least one longitudinally continuous channel 25a. As a result, the thickness d of the strap 6a is reduced even further in this area, which leads to a further reduction of the flexing when overflowing the deflection surface 21a (FIG. 7). Therefore, it is of course expedient, above all, also to provide the top apron 6b (FIG. 11) with such a longitudinal channel 25b in order to reduce the flexing process also in the region of the deflection surface 21b.

Another variant for the straps 6a, 6b is shown in FIGS. 12 and 13. Thereafter, the surface 23 (Fig. 8) is not roughened as in Fig. 8 and 9, but with in Längsbzw. Transport direction provided by continuous, formed in the manner of saw teeth longitudinal grooves 26a. In these longitudinal grooves 26a, the fibers of the fiber material 2 can lay during transport, whereby a running away transversely to the transport direction running away of the fibers is prevented. This is especially true when the upper apron 6b is provided on its side facing the lower apron 6a with corresponding longitudinal grooves 26b (FIG. 13).

14 and 15 show an embodiment in which on the side facing away from the fiber material 2 side of the straps 6a, 6b meandering a plurality of longitudinal channels 27a, 27b are introduced, for example by grinding. As a result, the bending stiffness of the Riemchen 6a, 6b and thus the influence of the Walkung compared to Fig. 10 and 11 even further reduced. This embodiment is particularly useful for the upper apron 6b, where the flexing in the region of the deflecting 5b so far represents a problem.

Finally, FIG. 16 shows an exemplary embodiment in which a longitudinal channel 28a, 28b in the respective strap surface is formed on the sides of both straps 6a and 6b which carry fibers. These longitudinal channels 28a, 28b are arranged so that they face each other in the state of use with their open sides and thereby form a chamber extending in the transport direction for the fiber material 2, which reliably prevents lateral escape of the fiber material 2. Of course, the same effect can also be achieved in that only one of the two straps 6a, 6b is formed with a longitudinal channel 28a, 28b in FIG. 16 and adjoins it with the smooth or roughened or otherwise shaped surface of the respective other strap facing it. Such a Riemchenform is particularly in the

Processing of long, z. B. made of wool fibers appropriate and suitable for fast-running drafting, where a lateral escape of fibers due to unavoidable air turbulence can not be excluded.

In order to reduce the energy consumption, in particular of high-performance drafting systems, it may further be expedient to use straps 6a, 6b which, on their sides facing away from the fiber material 2, are provided with surfaces which have favorable coefficients of friction. According to FIG. 17, this can be achieved, for example, by virtue of the fact that the straps 6a, 6b designed on their rear side 29 facing away from the fiber material 2 have a fabric insert 30 which protrudes at least partially from the remaining strapping material and with respect to the material of the deflecting elements 5a, 5b has a low coefficient of friction. An opposite surface 31 of the straps 6a, 6b intended for guiding the fibers can in this case be made of a material suitable for guiding the fibers. By contrast, FIG. 18 shows an embodiment in which particles 32 are embedded in a rear side of the apron material facing away from the fiber material 2, which particles provide a low coefficient of friction with respect to the deflecting elements 5a, 5b. Again, the other surface may be useful in guiding fibers be educated. The embodiments according to

FIGS. 17 and 18 are therefore used with particular advantage for the driven upper aprons 6b in order to obtain favorable friction conditions in the region of the deflecting element 5b.

The invention is not limited to the described embodiments, which can be modified in many ways. This applies in particular to those shown in FIGS. 8 to 18 Riemchenformen that are indeed particularly advantageous, but only represent possible embodiments, which may also be deviated. Furthermore, straps, in particular Oberriemchen, preferably made of a slightly elastic material such. As polyurethane, since in this case for tensioning the straps the material inherent elasticity can be used. When using inelastic materials, on the other hand, it is expedient for the upper apron 6b to provide a tensioning element 8 corresponding to the tensioning means. Furthermore, for the purpose of laying the deflection points of the straps 6a, 6b deeper into the gusset 15, it may be expedient to use rail-like components for the deflection elements 5a, 5b and, as indicated in FIG. 7, approximately along the angle bisector to arrange that angle, which is formed by the running on the deflection or running away from these Riemchenteile. In addition, it is clear that the deflection elements 5 a, 5 b are preferably formed and arranged so that the jaw width in

Region of the exit slit 7 of the straps 6a, 6b can be adjusted continuously and reproducibly. Furthermore, the invention is not limited to drafting systems with three pairs I, II and III of drafting system organs, but can be applied in particular in drafting systems with four or more pairs of drafting device organs. Finally, it is understood that the various features may be applied in combinations other than those described and illustrated.

Claims

claims 1. drafting device for refining fiber material (2) with at least one first apron assembly comprising a roller (4b), at least one deflecting element (5b) arranged at a distance therefrom and having a deflecting surface, and a first, via the roller (4b) and the deflecting surface laid, for guiding the fiber material certain strap (6b) contains, characterized in that the deflecting element (5b) in the region of the deflection surface (21b) has a radius of curvature of less than 2 mm and the strap (6b) has a thickness (d) of not more than 0.7 mm. 2. drafting system according to claim 1, characterized in that at least the Oberriem- Chen (6b) has a thickness (d) of at least 0, 1 mm. 3. drafting system according to claim 1 or 2, characterized in that at least the upper apron (6b) has a thickness d corresponding to the inequality 0.2 mm ≤ d <0.6 mm. 4. drafting system according to one of claims 1 to 3, characterized in that the deflection surface has a radius of curvature of 0.5 mm to 1.5 mm. 5. drafting system according to one of claims 1 to 4, characterized in that the first strap assembly comprises a driven, with a Oberriemchen (6b) provided upper roller (4b) and that a second, cooperating with the first strap assembly, appropriately trained Slip assembly is provided, which has a driving, with a Unterriemchen (6a) provided lower roller (4a). 6. drafting system according to one of claims 1 to 5, characterized in that the Oberriemchen (6 b) is held under such a bias that it is claimed on its entire length only to train. 7. drafting arrangement according to one of claims 1 to 6, characterized in that the two straps (6a, 6b) in the region of the front in the transport direction of the pair (III) factory organs (9a, 9b) via deflecting elements (5a, 5b) are guided, which are arranged with an offset in the transport direction offset relative to each other. 8. drafting system according to one of claims 1 to 7, characterized in that at least one of the two straps (6a, 6b) on a the fiber material (2) facing Side has a roughened surface (23). 9. drafting system according to one of claims 1 to 8, characterized in that at least one of the two straps (6a, 6b) on a the fiber material (2) facing side having a longitudinal grooves (26a, 26b) provided surface. 10. Drawframe according to one of claims 1 to 9, characterized in that at least one of the two straps (6a, 6b) on a the fiber material (2) facing side with a longitudinal channel (28a, 28b) provided surface, wherein the longitudinal channel (28a, 28b) forms, together with the other of the two straps (6a, 6b), a chamber for the fiber material (2) which extends in the transporting direction. 11. drafting system according to claim 10, characterized in that both straps (6a, 6b) on each side facing each have a longitudinal channel (28a, 28b) and the two longitudinal channels (28a, 28b) extending in the transport direction chamber for the fiber material ( 2) form. 12. Drawframe according to one of claims 1 to 11, characterized in that at least one of the two straps (6a, 6b) on a side facing away from the fiber material (2) side with at least one longitudinal channel (25a, 25b, 27a, 27b) having provided surface. 13. Drawframe according to one of claims 1 to 12, characterized in that at least one of the two straps (6a, 6b) on a side facing away from a for guiding fiber material (2) side has a surface with the friction coefficient with respect to the deflecting elements (5a, 5b) reducing means (30, 32) is provided. 14. straps for a Riemchenstreckwerk according to one of claims 1 to 8, characterized in that it is provided on a for guiding fiber material (2) certain side with a longitudinal grooves (28 a, 28 b) having surface. 15. straps according to claim 13, characterized in that it is provided on a for guiding fiber material (2) certain side with a longitudinal channel having (28 a, 28 b) surface. 16. The apron according to claim 14 or 15, characterized in that it has on one side, which faces away from a for guiding fiber material (2) side, with at least one longitudinal channel (25a, 25b, 27a, 27b) provided surface , 17. A strap according to any one of claims 14 to 16, characterized in that it faces away from a side intended for guiding fiber material (2) side has a surface with the friction coefficients with respect to the deflection elements (5a, 5b ) reducing means (30, 32) is provided.