Title of Invention

PNEUMATIC CONDENSING DEVICE FOR A FIBRE COMPOSITE AND METHOD FOR THE PNEUMATIC CONDENSING OF A FIBRE COMPOSITE

Abstract

Pneumatic condensing device (10) for a fibre composite (2) which has preferably previously been drafted in a region of a drawframe (1) of a spinning machine, with a transport means (15) for the fibre composite (2) and with a cover (30), characterized in that the cover (30) has at least one guide means (31,31') for the air causing the condensing, the said guide means extending in the running direction of the fibre composite (2).

Full Text

Field of the invention:- The invention relates to a pneumatic condensing device for a fibre composite which has preferably previously been drafted in a drawframe of a spinning machine, according to the following description. Background and prior art:- What is known as a double-apron drawframe is already known as general prior art (DE 43 23 472 C2). Here, the fibre composite leaving the pair of delivery rollers is exposed, over the length of the fibre bundling zone, to a suction-airstream running transversely to the transport direction. The fibre composite is in this case acted upon by a plane transport means which is designed as a perforated apron. The apron can be driven by means of a roller drive. The apron is guided by an apron cage which is designed as a suction-extraction device. The apron cage possesses a groove, closed on one side, for guiding the suction air. A support is provided which is designed as a rectangular profile. The support is mounted adjustably; its inclination can be modified and consequently the start of condensing can be regulated. By means of the said support, the sucked-in air can be utilized as a lateral force component, this having an advantageous effect on the desired condensing of the fibre composite. DE 197 22 528 A1 is to be seen as a development of the abovementioned prior art for the present invention. Here, the apron possesses perforations formed in a different size in the running direction, so that, after a rough congregation of the fibre . composite by means of the large perforations, the actual condensing of the latter takes place by means of the perforations which are kept smaller. A good condensing of the fibre composite is thereby achieved. The yarns produced thereafter satisfy high quality demands. Recently, however, there have been requirements for yarns of still higher quality. By means of a further development, as described in Melliand Textile Reports 4/2001 on pages 246 to 248, a substantial improvement is achieved in that a cover is placed opposite the suction orifice of the suction shoe. Sucked-in air can thereby be utilized in a controlled way as a lateral force component; the suction-airstream is forced into a flow running laterally towards the fibre composite, with the result that a greater traversing width is possible. In conjunction with the length of the condensing zone, a good fixing of the fibre composite on the perforation of the apron can be achieved. The yarns produced accordingly fulfil higher quality demands. Recently, however, there have been requirements for yarns of even higher quality. It was shown that, in many instances, an airflow running along the fibre composite is suitable for laying projecting fibre ends onto the fibre composite particularly effectively. Immediately before the airflow passes through the air-permeable transport means, the suction-airstream is deflected into a direction transverse to the fibre composite, flows through the latter and at the same time condenses it. Object of the invention:- The object of the present invention is to improve a condensing device of the abovementioned type in as simple and as cost-effective a way as possible. This object is achieved, according to the invention, in that a cover is provided, which has at least one guide means for the air causing the condensing, the said guide means extending in the running direction of the fibre composite. This makes it possible to have an airflow running preferably along the fibre composite and therefore excellent condensing. The guide means may be designed, for example, as elevations in the manner of a pair of rails, but preferably, because of more cost-effective practicability and a saving of material, as a groove. When, in an embodiment of the invention, the cross-sectional area of the groove is markedly larger than the diameter of the fibre composite running through the groove, what is achieved, on the one hand, is that the said groove opposes low resistance to the sucked-in air and has established in it a strong airstream along the fibre composite running through. . What is achieved, on the other hand, is that the fibre composite does not slide along on the flanks of the groove and is not, for example, roughened there. The fibre composite is therefore in no way condensed mechanically by the groove. The cross-sectional area of the groove may be angular or rounded. Advantageously, it narrows in the direction of the fibre run. Since air is suction-extracted from the groove over the course of the condensing zone, what can be achieved thereby is that the velocity of the airflow along the fibre composite remains approximately of the same magnitude in this condensing zone. The flanks of the groove may be straight or convexly curved, and they may also run, in an initial region, in a funnel-like manner towards one another and then in parallel. A particularly strong airflow along the fibre composite is achieved when, in a further embodiment of the invention, care is taken to ensure that only a clearance such as to allow the transport means to run through without jamming is provided between that face of the suction shoe which has the air inlet orifice and the cover. As a result, a lateral approach flow of condensing air, as is sought after in known condensing devices, is, in contrast to these, as far as possible prevented in the device according to the invention. Further advantageous details and embodiments of the invention may be gathered from the following disclosure. The invention proceeds from a condensing device which consists, for example, of a suction shoe with a vacuum connection and, as transport means, of a perforated apron guided around a feed roller. The apron has a plurality of perforations arranged one behind the other in the running direction of the fibre composite. As soon as the fibres of the non-condensed fibre composite are picked up by the suction-airflow, they are pushed together by the latter and condensed. The invention, then, is explained further with reference to the accompanying drawings which illustrate a preferred exemplary embodiment. Brief description of the accompanying drawinas:- Fig. 1 shows a diagrammatic side view of a double-apron drawframe with run-in rollers, the main drafting zone, a condensing device and a feed device, Fig. 2 shows an enlarged illustration of the condensing device with a suction shoe and a suction connection in a diagrammatic side view, Fig. 2a shows a details of Fig. 2 in an enlarged illustration, and Fig. 3 shows a detail of Fig. 1 and 2 in a top view. Detailed Description of the preferred embodiment:- Fig. 1 and 2 illustrate a drawframe 1 for a spinning machine for the drafting and bundling of a fibre composite 2. The said drawframe has a first pair of rollers 3 and a second pair of rollers 4 which is followed by a pair of delivery rollers 5. The main drafting of the fibre composite 2 takes place in the region between the second pair of rollers 4 and the pair of delivery rollers 5. The pair of delivery rollers 5 has adjacent to it a pneumatic condensing device 10. The latter is followed by a feed device 20 which again has a pair of rollers 6. The fibre composite 2 is transported in the direction of the arrow between and through the pairs of rollers 3, 4, 5, 6 preferably driveable electromotively in a known way. In this case, the transport means 15, here designed as an apron, which is provided with perforations 16 is used, as is known, for example, from DE 197 22 528 Al already mentioned above. In the region between the pair of delivery rollers 5 and the pair of rollers 6 of the feed device 20 lies what is known as a fibre bundling zone 7. Here, the fibre composite 2 leaving the pair of delivery rollers 5 of the drawframe 1 is exposed to a suction-airstream 8 (Fig. 3) . The suction-airstream 8 is generated by a suction-extraction device 9 which extends between the pair of delivery rollers 5 and the feed device 20 on that side of the transport means 15 which faces away from the fibre composite 2. The suction-extraction device 9 has a suction shoe 17, over which the perforated apron, that is to say the transport means 15, is guided. Preferably, the perforations 16 of the transport means 15 run at least over a traversing width of the fibre composite 2 which emerges from the pair of delivery rollers 5 and which is guided correspondingly via the suction orifice of the suction shoe 17 of the suction-extraction device 9. The suction shoe 17 is positioned between the pair of rollers 5 and 6 in such a way that it is nearer to the centre points of the rollers (of circular cross section, as is generally customary) arranged at the bottom than to those of the rollers arranged at the top. The suction shoe 17 thus projects relatively far downwards into the fibre bundling zone 7. A cover 30 is arranged opposite the suction orifice of the suction-extraction device 9. The cover 30 is designed as a rail and extends over the entire width of the drawframe 1. The said cover itself possesses a width B which is co-ordinated with the size of the suction orifice of the suction-extraction device, in particular is approximately the same size as the said suction orifice in the running direction of the fibre composite 2. Between that face 18 of the suction shoe 17 which has the air inlet orifice and the cover 30, there is a clearance which ensures that the apron 15 runs through without jamming. The suction shoe 17 is supported with a nose 19 on the cover 30, as shown in Fig. 2a. As shown in Fig. 1 and 2, the cover 30 is designed to be curved downwards and, as seen in the running direction of the fibre composite 2, is slightly higher at the rear than at the front. The cover 30 has guide means 31, 31' for the fibre composite 2. The guide means 31, 31' are designed as grooves and extend with their length L straight ahead over the entire width B of the cover 30 in the running direction of the fibre composite 2. The width of the grooves 31, 31' is co-ordinated with the thickness of the fibre composite 2; as shown in Fig. 3, their cross section is markedly larger than that of the fibre composite 2 running through them. In the exemplary embodiment shown in the middle and on the right in Fig. 3, the grooves 31 are of rectangular cross section and, at the start, possess a width bl which is approximately twice as large as the thickness of the non-condensed fibre composite 2. After about one quarter of their length L, the grooves 31 narrow to a width B2 which is about half as large as the width bl. The flanks 32 of the grooves 31 thus approach one another in the entry region of the fibre composite and then run further on parallel to one another. The groove depth corresponds here to at least about the thickness of the non-condensed fibre composite 2. In the left-hand region of Fig. 3 is illustrated a groove 31', the flanks 32' of which are convexly curved. The groove 31' is otherwise designed identically to the grooves 31. Overall, therefore, the grooves 31, 31' are designed in the manner of a suction duct in which a strong airstream is established along the fibre composite 2 running through. This makes an excellent condensing of the fibre composite 2 possible. By the method according to the invention, the fibre composite 2 can not only be exposed to an airstream in the fibre running direction, as described above, but simultaneously or subsequently to an airstream transverse thereto, in order to achieve the best possible condensing. In this case, the velocity of the air causing the condensing should be higher by a multiple than the velocity of the fibre composite 2 running through. It may amount to up to ten times the velocity of the fibre composite. In practice, it is proved highly effective for the velocity selected for the air causing the condensing to be approximately twice as high as the velocity of the fibre composite 2 running through. A major advantage in the device according to the invention and of the method according to the invention is that, as compared with known devices and methods, the air requirement is reduced precisely because of the guide means according to the invention for the air causing the condensing, and more economical operation is thereby ensured. In addition to the suction air, blowing air may also be employed in order to assist the condensing action of the suction air. An even better condensing of the fibre composite and therefore, ultimately, an even higher yarn quality can thereby be achieved. In conclusion, it should also be mentioned that the invention can, of course, also be used in condensing devices which have transport means, for example, in the form of a screen apron. The suction orifice is then preferably designed as a narrow, straight or oblique suction slot. In the case of an oblique suction slot, the groove must, of course, be tailored to the oblique position of the slot. The invention can be used likewise in condensing devices which have transport means, for example, in the form of a rigid driven drum or in the form of a rotating sleeve which possess a screen surface or a perforation track. We Claim: 1. Pneumatic condensing device (10) for a fibre composite (2) which has preferably previously been drafted in a region of a drawframe (1) of a spinning machine, with a transport means (15) for the fibre composite (2) and with a cover (30), characterized in that the cover (30) has at least one guide means (31,310 for the air causing the condensing, the said guide means extending in the running direction of the fibre composite (2). 2. Condensing device as claimed in Claim 1, wherein the guide means (31, 310 is designed as a groove. 3. Condensing device as claimed in Claim 2, wherein the cross-sectional area of the groove (31, 310 is markedly larger than the diameter of the fibre composite (2) running through the groove (31, 31') 4. Condensing device as claimed in Claim 2 or 3, wherein the groove (31, 310 narrows in the running direction of the fibre composite (2). 5. Condensing device as claimed in Claim 4, wherein the flanks (320 of the groove (31') are convexly curved. 6. Condensing device as claimed in Claim 4, wherein the flanks (32) of the groove (31) approach one another in the entry region of the fibre composite (2) and then run in parallel. 7. Condensing device as claimed in one of the preceding claims, wherein the transport means (15) is designed as an apron. 8. Condensing device as claimed in one of the preceding claims, wherein the apron (15) has perforations (16). 9. Condensing device as claimed in one of the preceding claims, wherein it has a suction-extraction device (9) with a suction shoe (17) with a vacuum connection. 10. Condensing device as claimed in Claim 9, wherein between that face (18) of the suction shoe (17) which has the air inlet orifice and the cover (30), there is a defined clearance which ensures that the transport means (15) runs through without jamming. 11. Condensing device as claimed in Claim 10, wherein the clearance is ensured by means of a spacer. 12. Condensing device as claimed in Claim 10 or 11, wherein the suction shoe (17) is supported with a nose (19) on the cover (30). 13. Method for the pneumatic a fibre composite (2), in which the fibre composite (2) is exposed both to an airstream in the running direction and to an airstream transverse thereto. 14. Method as claimed in Claim 13, wherein the velocity of the air causing the condensing is higher by a multiple than the velocity of the fibre composite (2) running through. 15. Method as claimed in Claim 14, wherein the velocity of the air causing the condensing is approximately twice as high as the velocity of the fibre composite (2) running through. Pneumatic condensing device (10) for a fibre composite (2) which has preferably previously been drafted in a region of a drawframe (1) of a spinning machine, with a transport means (15) for the fibre composite (2) and with a cover (30), characterized in that the cover (30) has at least one guide means (31,31') for the air causing the condensing, the said guide means extending in the running direction of the fibre composite (2).

Documents:

1627-kolnp-2004-granted-abstract.pdf

1627-kolnp-2004-granted-claims.pdf

1627-kolnp-2004-granted-correspondence.pdf

1627-kolnp-2004-granted-description (complete).pdf

1627-kolnp-2004-granted-drawings.pdf

1627-kolnp-2004-granted-examination report.pdf

1627-kolnp-2004-granted-form 1.pdf

1627-kolnp-2004-granted-form 18.pdf

1627-kolnp-2004-granted-form 2.pdf

1627-kolnp-2004-granted-form 26.pdf

1627-kolnp-2004-granted-form 3.pdf

1627-kolnp-2004-granted-form 5.pdf

1627-kolnp-2004-granted-reply to examination report.pdf

1627-kolnp-2004-granted-specification.pdf

1627-kolnp-2004-granted-translated copy of priority document.pdf