Title of Invention	AN AIR-PREAMBLE SMOOTH TRANSPORT BELT FOR TRANSPORTING A FIBRE STRAND TO BE CONDENSED.
Abstract	TITLE: AN AIR-PREAMBLE TRANSPORT BELT FOR TRANSPORTING A FIBRE STRAND TO BE CONDENSED. 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 with comprises a perforated effective area having fine perforations, which covers the suction slit.

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 an air-permeable transport 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 teaf-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 beltis, in this case, perforated and is designed as a mesh belt or a sieve foil or advantageously as a close-meshed woven belt, which is driven glidingly over a hollow profile which comprises the suction slit. In the design of a woven belt it is advantageously possible to provide a plurality of openings in a very small space, so that a very homogenous air stream is generated. At the points of intersection between the warp threads and the weft threads, tiny open gores form in which the fibres can adhere. The trapped fibres can, in time, block the perforations and thus impair the condensing effect. In the case of the mesh belt or the sieve foil variations, the above mentioned disadvantage is avoided, but the distance between the holes is significantly larger than in the case of the woven belt, so that the air stream is less homogenous. It is an object of the present invention to produce a transport belt of the above mentioned type, in which the risk of a reduction in air-permeability with increasing operating time is avoided to a great extent, and in which an entirely homogenous air stream is possible at the same time. This object has been achieved in accordance with the present invention in that the normally smooth transport belt comprises a perforated effective area having fine perforations, which effective area covers the suction slit. The term,line perforations can be taken to mean here a perforation whose holes have the smallest possible diameter and which are arranged as close as possible to one another. An air-permeability is thus achieved which is similar to that of a woven belt. An air stream is thus generated which is, to a great extent, homogeneous, without the risk of fibres getting trapped between the open gores of the threads. As the suction slit extends essentially in transport direction of the transport belt and is at most slightly inclined thereto, it is sufficient when the effective area having the fine perforations measures only approximately 10 mm. In this effective area, the fine perforations should when possible have a free air permeability cross section of at least 15%. This is then possible when the fine perforationas have a plurality of individual holes having a diameter of maximum 0.2 mm. The fine perforations are created by needle piercing, for example by means of a needle roller, whose needles have a very small diameter and which are arranged very close to one another. The transport belt itself can be made of a polyamide, so that it has a very smooth surface on the outside. In order that the fibre strand to be condensed is disposed as closely as possible to the suction slit, the transport belt has a maximum thickness of 0.5 mm. 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 partial view of the effective area of Figure 2 comprising fine perforations. 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) 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)ends. 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) or pneumatically condensing the fibre strand^l 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 conduitCl I)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 Q 3), which is driven to circulate and to transport the fibre strand(83bver the suction slit(]l2)and through the condensing zon^^) The transport belt (13) is air-permeable in an effective area(14) having a width (a). The effective width (a) measures approximately (10 mm) thus ensuring that the suction slit(12)is completely covered. Adjacent to both sides of the effective area(l4)there is a border zone(l 5)and(l 6) which serves the friction drive of the transport belt The transport belt(l3)is driven by a nipping roller(17) which in turn receives its drive from the front top roller(5)by means of a transfer roller (l 8) The nipping roller(17)forms together with the transport belt(13)and the hollow profile(10)a nipping line(19), which borders the condensing zone(9)on its exit side and which, regarding the thread(20)to be spun, effects a twist block, preventing the imparted spinning twist from running back to the condensing zone(9). The thread(20)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(19) to which point the twist runs back. The spun thread(20)is thus more even, more tear-resistant and less hairy. In order to prevent the transport belt(13)becoming blocked with fibres, or to prevent it from becoming insufficiently air-permeable, it is provided according to the present invention, that the usually smooth transport belt(13)comprises a perforated effective area(l4)comprising fine perforations(2), which area (l4)covers the suction slit(12) The fine perforations(2l)comprise a plurality of individual holes^22j!) which have on the one hand very small diameters and on the other are arranged very closely to one another and are at least so designed, that in the effective area(l4 a)free air permeability cross section of at least 15% of the entire surface occurs. The fine perforations(21) can be advantageously created for this purpose by means of a correspondingly designed needle roller. WE CLAIM 1. An air-permeable smooth transport belt for transporting a fiber strand over a suction slit of a condensing zone of a spinning machine, wherein the transport belt (13) comprises a perforated effective area (14) having fine perforations (21), said effective area (14) covering the suction slit (12). 2. A transport belt as claimed in claim 1, wherein the effective area (14) has a width (a) of for example 10 mm. 3. A transport belt as claimed in claim 1 or 2, wherein the fine perforations (21) in the effective area (14) have an air permeability cross section of at least 15% and the transport belt is made of flexible plastic material. 4. A transport belt as claimed in any one of the claims 1 to 3, wherein the fine perforations (21) comprise a plurality of individual holes (22) having a diameter of maximum 0.2 mm. 5. A transport belt as claimed in any one of the claims 1 to 4, wherein the fine perforations (21) are created by needle piercing. 6. A transport belt as claimed in any one of the claims 1 to 5, wherein the transport belt (13) is made of polyamide. 7. A transport belt as claimed in any one of the claims 1 to 6, wherein the transport belt (13) measures a maximum of 0.5 mm in thickness. 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 with comprises a perforated effective area having fine perforations, which covers the suction slit.

Documents:

00546-cal-2000-abstract.pdf

00546-cal-2000-assignment.pdf

00546-cal-2000-claims.pdf

00546-cal-2000-correspondence.pdf

00546-cal-2000-description (complete).pdf

00546-cal-2000-drawings.pdf

00546-cal-2000-form 1.pdf

00546-cal-2000-form 18.pdf

00546-cal-2000-form 2.pdf

00546-cal-2000-form 26.pdf

00546-cal-2000-form 3.pdf

00546-cal-2000-form 5.pdf

00546-cal-2000-form 6.pdf

00546-cal-2000-letter patent.pdf

00546-cal-2000-priority document others.pdf

00546-cal-2000-priority document.pdf

00546-cal-2000-reply f.e.r.pdf

546-CAL-2000-FORM-27.pdf