Title of Invention	AN AIR-PERMEABLE TRANSPORT BELT FOR TRANSPORTING A FIBRE STRAND TO BE CONDENSED
Abstract	In order to transport a fibre strand to be pneumatically condensed over a suction slit of a condensing zone of a spinning machine, a transport belt is provided which is woven from filament threads. The mesh width of the filament threads measures at most 0.08 mm. In order to achieve a free airflow area of at least 22%, the mesh width is larger than the diameter of the filament threads.

Full Text

BACKGROUND AND SUMMARY OF THE INVENTION An air-permeable transport belt for transporting a fibre strand to be condensed The present invention relates to a transport belt in the form of an air-permeable woven belt for transporting a fibre strand to be pneumatically condensed over a suction slit of a condensing zone of a spinning machine. For the pneumatic condensing of a fibre strand leaving a drafting unit of a spinning machine it is essential that the fibre strand is transported in the condensing zone disposed on an air-permeable transport element and still in a twist-free state and having fibres lying essentially parallel to one another, and that in the condensing zone an air stream is generated which flows through the transporting element, which air stream, depending on its width and/or direction determines the degree of condensing and which positions the fibres transversely to the transport direction and thus bundles or condenses the fibre strand. In the case of a fibre strand condensed in this way, a spinning triangle does not occur when twist is being imparted, so that the thread produced is more even, more tear- resistant and less hairy. A transport belt of the above mentioned type is described in connection with a condensing arrangement in German published patent application 198 46 268. The transport belt is, in this case, perforated and is designed as a close-meshed woven belt, which is driven glidingly over a hollow profile which comprises the suction slit. When designing the woven belt it is possible to provided a plurality of openings in a very small space, so that a very homogenous air stream is possible. It is an object of the present invention to optimize a transport belt of the above mentioned type with regard to the air flow. This object has been achieved in accordance with the present invention in that the transport belt is woven from filament threads, whose mesh width measures at most 0.08 mm and which, in order to achieve a free air flow area of at least 22%, is larger than the diameter of the filament threads. It has been shown that, the smaller the mesh width is, the more homogeneous the air stream through the woven belt is. A very small mesh width is furthermore very advantageous with regard to blockage of the perforation, as the fibres as a rule cannot get through the very small perforations. On the other hand, a sufficiently large free airflow area should be present despite the very small mesh width, whereby a free area of at least 22% has been shown to be favourable. This can, as a rule, only be achieved when the diameter of the filament threads is smaller than the mesh width. In a particular embodiment of the present invention, the diameter of the filament threads is smaller than 0.06 mm. Even smaller diameters than this are curtailed only by the fact that too great a wear or too short a lifetime are not desirable. BRIEF DESCRIPTION OF THE DRAWINGS These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings wherein: Figure 1 is a partly intersectional side view of an embodiment of a condensing apparatus comprising a transport belt according to the present invention; Figure 2 is a view in the direction of the arrow II of Figure 1 onto the condensing zone, Figure 3 is, in greatly enlarged dimensions, a part view onto the transport belt in the form of a woven belt. DETAILED DESCRIPTION OF THE DRAWINGS In the embodiment according to Figures 1 and 2, only the area of a front roller pair 2 and of an apron roller pair 3 upstream thereof are shown of a drafting unit 1 of a spinning machine. The front roller pair 2 comprises in a known way a driven front bottom roller 4 extending in machine longitudinal direction, to which front bottom roller 4 one front top roller 5 per spinning station is arranged. By means thereof, a front nipping line 6 is formed, at which the drafting zone of the drafting unit 1 is ended. A sliver or roving 7 is guided through the drafting unit 1 in transport direction A and drafted to the desired degree. Directly downstream of the front nipping line 6 is a drafted, but still twist-free fibre strand 8. A condensing zone 9 lies downstream of the drafting unit 1 for pneumatically condensing the fibre strand 8, which is still in a twist-free state. A hollow profile 10, extending over a plurality of spinning stations, preferably a machine section, is arranged to the condensing zone 9, which hollow profile 10 is connected by means of a vacuum conduit 11 to a vacuum source (not shown). A suction slit 12 is arranged to each condensing zone 9, which suction slit 12 extends essentially in transport direction A, but preferably somewhat inclined thereto, as can be seen in Figure 2. The outer contour of the hollow profile 10 is designed at least in the area of the suction slit 12 as a sliding surface for an air-permeable transport belt 13, which is driven to circulate and to transport the fibre strand 8 over the suction slit 12 and through the condensing zone 9. The transport belt 13 is designed as a woven belt, which is described below with the aid of Figure 3. The transport belt 13 is driven by a nipping roller 14, which in turn receives its drive from the front top roller 5 by means of a transfer roller 15. The nipping roller 14 forms together with the transport belt 13 and the hollow profile 10 a nipping line 16, which borders the condensing zone 9 on its exit side and which, regarding the thread 17 to be spun, effects a.twist block, preventing the imparted spinning twist from running back to the condensing zone 9. The thread 17 is fed directly downstream of the condensing zone 9 in delivery direction B to a twist device (not shown), for example, a ring spindle. The condensing of the fibre strand 8 serves the purpose of preventing the formation of a spinning triangle at the nipping line 16 to which point the twist runs back. The spun thread 17 is thus more even, mote tear-resistant and less hairy. The transport belt 13 is, as can be seen in the greatly enlarged dimensions of Figure 3, in the form of a woven belt 18. This woven belt 18 is woven from filament threads 19, which are preferably made of polyamide and whose diameter d is the same for the warp as well as for the weft. In order to attain the most homogeneous air flow possible through the transport belt 13 and in order to avoid fibre fly in the perforations, it is provided that the mesh width w of the woven belt 18 measures at most 0.08 mm. In order to achieve a good condensing effect, however, the free air flow area 20 should amount to at least 22% of the entire woven surface. This can then be achieved when the diameter d of the filament threads 19 is smaller than the mesh width w. The diameter d is thus adapted accordingly, and can, in a preferred embodiment, measure even less than 0.06 mm. We Claim: 1. A transport belt in the form of an air-permeable woven belt for transporting a fibre strand over a suction sitt of a condensing zone of a spinning machine, characterized in that the transport belt (13) is woven from filament threads (19), whose mesh width (w) in order to achieve a free airflow area (20) of more than 22%, is larger than the diameter (d) of the filament threads (19). 2. A transport belt as claimed in claim 1, wherein the diameter (d) of the filament threads (19) measures less than 0.06 mm. In order to transport a fibre strand to be pneumatically condensed over a suction slit of a condensing zone of a spinning machine, a transport belt is provided which is woven from filament threads. The mesh width of the filament threads measures at most 0.08 mm. In order to achieve a free airflow area of at least 22%, the mesh width is larger than the diameter of the filament threads.

Documents:

547-CAL-2000-FORM-27.pdf

547-cal-2000-granted-abstract.pdf

547-cal-2000-granted-assignment.pdf

547-cal-2000-granted-claims.pdf

547-cal-2000-granted-correspondence.pdf

547-cal-2000-granted-description (complete).pdf

547-cal-2000-granted-drawings.pdf

547-cal-2000-granted-examination report.pdf

547-cal-2000-granted-form 1.pdf

547-cal-2000-granted-form 18.pdf

547-cal-2000-granted-form 2.pdf

547-cal-2000-granted-form 3.pdf

547-cal-2000-granted-form 5.pdf

547-cal-2000-granted-form 6.pdf

547-cal-2000-granted-priority document.pdf

547-cal-2000-granted-reply to examination report.pdf

547-cal-2000-granted-specification.pdf

547-cal-2000-granted-translated copy of priority document.pdf