Title of Invention

A DEVICE FOR GUIDING A BOTTOM APRON IN DRAFTING DEVICES

Abstract

A Device for guiding a bottom apron in drafting units for drafting fibre strands comprises a guiding table for the bottom apron,a rotatable deflecting roller for the bottom apron and a bearing arrangement for the deflecting roller.The bearing arrangement comprises a radial and a axial bearing .The deflecting roller is held in guiding table by the radial and the axial bearing. The radial bearing can comprise means,for example a magnet,for preventing the deflecting roller from falling out.

Full Text

BACKGROUND AND SUMMARY OF THE INVENTION A device for guiding a bottom apron in drafting devices The present invention relates to a device for guiding a bottom apron in drafting units for drafting fibre strands, which device comprises a guiding table for the bottom apron, a rotatable deflecting roller for the bottom apron and a bearing arrangement for the deflecting roller. In drafting devices for drafting fibre strands, a number of roller pairs are normally applied, said roller pairs being arranged one behind the other and which can be driven with increasing circumferential speed. It is standard practice to apply guiding aprons, which can loop a top roller or a bottom roller. The guiding aprons effect a better evenness of the drafted fibre strand, in that they guide the fibres between two nipping lines of adjacent roller pairs. The guiding aprons are usually guided and deflected by stationary guiding devices such as top apron cradles or guiding tables for the bottom apron. Stationary guiding devices of this type have the disadvantage in that they exert a relatively high braking effect on the guiding aprons, thus accordingly causing the necessity for high drive performance from the drafting rollers. In the German utility patent 68 05 009 a device for guiding a bottom apron of the above mentioned type is known, in which the bottom apron is not deflected by a stationary deflecting edge of the guiding table, but rather instead by a rotatable deflecting roller. The rotatable deflecting roller has the advantage in that it brakes the bottom apron significantly less than a stationary bottom apron bar. The deflecting roller is hereby supported in bearing slides, which are affixed to the roller stands in a movable way. The deflecting roller has a relatively large diameter, which is necessary in the case of the shown bearing arrangement, so that no inacceptable bending under load of the deflecting roller occurs, as there is a relatively large distance between the bearing slides. The large diameter of the deflecting roiler is hereby disadvantageous, as the guidance of the fibre strand by the bottom apron already ends at a very great distance upstream of the nipping line of the following roller pair. The fibres of the fibre strand are thus without any guidance for a relatively long distance. Furthermore, the known bearing arrangement of the deflecting roller has the disadvantage in that in the case of an inevitable and necessary replacement of the bottom apron after a certain running time, the deflecting roller, as a further individual component in addition to the guiding table, has to be installed in under the new bottom apron. Such maintenance work thus takes up much time and effort. In the German published patent 26 33 75 a further device for guiding a bottom apron with a deflecting roller is known, said roller having a relatively small diameter. However, no indication as to the type or the arrangement of the bearing for the deflecting roller is disclosed. It is an object of the present invention to improve the known device and to avoid its disadvantages. This object has been achieved in accordance with the present invention in that the bearing for the deflecting roller comprises a radial and an axial bearing, and that the deflecting roller is supported by the radial and axial bearing in the guiding table. Due to the taking up of the radial and axial bearings in the guiding table, the deflecting roller is completely supported by the guiding table. Advantageously, a very small diameter can be selected for the deflecting roller. This permits the bottom apron to be brought very close to the nipping line of the following roller pair and the guidance of the fibre strand to be improved. Due to the support by means of the radial bearing at the stable guiding table, the deflecting roller longer is no longer subject to bowing under load and thus no longer needs to have a diameter of such large dimensions. A further advantage is that because of the bearing of the deflecting roller in the guiding table, the guiding table, together with the deflecting roller, forms a compact structural unit, which can be removed and fitted in again in one piece during maintenance work. The handling of a number of single parts is omitted. It is advantageously possible to select the length of the deflecting roller in such a way that it corresponds approximately to the width of the bottom apron to be guided. Thus for every bottom apron a separate deflecting roller can be provided. In an embodiment of the present invention it is provided that the radial bearing comprises means to stop the deflecting roller from falling out. The handling of the compact structural unit of guiding table and deflecting roller is thus further simplified. It is ensured that the deflecting roller cannot fall out of the radial bearing when the tension of the bottom apron slackens or ceases altogether. It is, in addition, advantageous when the means for preventing the falling out of the deflecting roller can act in a non-contact manner, in particular when they comprise at least one magnet. Thus the easy rotatability of the deflecting roller is hereby not impaired. At the same time a simple disassembly is made possible, when, for example, the deflecting roller has to be removed for cleaning purposes. In a further embodiment of the present invention it is advantageous when the axial bearing comprises at least one convex-shaped surface. In such an embodiment a slide bearing is possible which features extremly low levels of friction loss. It is hereby irrelevant whether the convex-shaped surface is designed at the front side of the deflecting roller or on the bearing surface of the guiding table for the deflecting roller. In a further embodiment of the present invention it can be advantageous to provide the material of the guiding table, at least in an area of a radial bearing designed as a slide bearing for the deflecting roller, with a material having good sliding properties or with a coating having good sliding properties. This can be particularly advantageously carried out using material containing polytetrafluoroethyiene (PTFE). 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 part intersectional side view of a part of a drafting unit comprising a device for guiding a bottom apron, Figure 2 is a view in the direction of arrow II of Figure 1 of the device for guiding the bottom apron, whereby many of the surrounding components of the drafting unit have been omitted. DETAILED DESCRIPTION OF THE DRAWINGS The drafting unit shown only partly in Figure 1 serves to draft a fibre strand 1. A sliver or roving 4 is fed in feed direction A to a number of roller pairs 2, 3 and drafted by these roller pairs 2, 3, which are driven at increasing speed, to the desired degree of fineness. The drafted fibre strand 5 is withdrawn in withdrawal direction B and can be provided with its spinning twist, for example, by means of a ring spindle, and further processed to a yarn. Depending on the type of fibre strand 1 to be drafted, it may be advantageous to arrange further roller pairs either upstream or downstream of the shown roller pairs 2, 3. The roller pairs 2, 3 comprise driveable bottom rollers 6, 8, which can be provided with grooves on their peripheral surfaces for the purposes of improved drafting of the fibre strand 1. Top rollers 7,9 respectively are flexibly pressed against the bottom rollers 6, 8, and form with the respective bottom roller 6, 8 a nipping line 10,11. Due to the. bottom roller 8, which is driven at a higher speed, the fibre strand 1 is drafted between the nipping lines 10 and 11 to a lesser fineness. For the purposes of guiding the fibre strand 1 to be drafted between the nipping lines 10 and 11, guiding aprons 12, 13 are arranged to the roller pair 2. The bottom apron 12 loops hereby the bottom roller 6 and is guided and tensioned by a device 14 for guiding the bottom apron 12. In a modification of the shown embodiment it can also be provided that the bottom apron is design significantly longer and is tensioned by a separate tensioning device. The top apron 13 loops the top roller 7 and is guided in the known way by a top apron guiding device (not shown), for example in the form of a top apron cradle. The device 14 for guiding the bottom apron 12 includes a guiding table 15, which is affixed to a stationary frame or to a roller stand of the drafting device in a way not shown. A rotatable deflecting roller 16 for the bottom apron 12 is arranged to the side of the guiding table 15 facing the roller pair 3. The deflecting roller 16 has, in comparison to the bottom roller 8, the smallest diameter possible, so that the bottom apron 12 can be placed as close to the nipping line 11 as possible. Due to the long guided distance of the fibre strand 1 between the nipping line 10 and 11 by the guiding aprons 12, 13, the evenness of the drafted fibre strand 5 is improved. In order to support the bottom apron 12 between the nipping line 10 and the deflecting roller 16, the surface of the guiding table 15 facing the bottom apron 12 can be variously designed in the known way. Depending on the type of fibre strand 1 to be drafted, embodiments of the guiding table 15 having a smaller or larger contact area, and with varying levels of elevation, have proved themselves in the field. The deflecting roller 16 is supported entirely in the guiding table 15 and forms with same a compact structural unit, which can be easily disassembled and re-installed for maintenance or cleaning purposes. The bearing arrangement for the deflecting roller 16 comprises hereby a radial bearing 17 in the form of a bearing shell, which surrounds a part of the periphery of the deflecting roller 16. The radial bearing 17 holds the deflecting roller 16 under the action of the tensioning forces of the bottom apron 12 in its position and supports the deflecting roller 16. Because of the small diameter of the deflecting roller 16, it is advantageous when the radial bearing 17 supports the deflecting roller 16 over its entire length. The deflecting roller 16 is taken along by the rotating bottom apron 12 and thus rotates. It is therefore advantageous to design the areas of the radial bearing 17 which come into contact with the deflecting roller 16 with material having good sliding properties or with a coating having same. Particularly advantageous are hereby materials containing deposits which favour a sliding action, for example polytetrafluoroethylene. Means 18 are provided in order to prevent the deflecting roller 16 from falling out due to decreased tension of the bottom apron 12. These means 18 can act on the deflecting roller 16 in a non-contact manner and contain a magnet 19. As shown in Figure 2, it is however advantageous to arrange a number of magnets 19 distributed along the length of the deflecting roller 16 in the guiding table 15. The bearing arrangement for the deflecting roller 16 contained in the guiding table 15 includes in addition an axial bearing 20, shown in Figure 2, with which said axial bearing 20 the deflecting roller 16 is positioned in axial direction. The axial bearing 20 is preferably formed by a convex-shaped surface 21 and a planar countersurface 22. In the shown embodiment, the convex-shaped surface 21 is arranged on the front side of the deflecting roller 16, while the countersurface 22 is formed by the guiding table 15. The reverse can just as well also be the case. The application of a convex surface 21 in the axial bearing 20 has the advantage that friction losses are minimized. In order to draft a large number of fibre strands 1 simultaneously, it is known that the bottom rollers 6, 8 are designed as a continuous bottom cylinder extending in machine longitudinal direction. A number of bottom aprons 12 are hereby arranged adjacently to, and at a certain distance from each other along the bottom roller 6. In this case it is advantageous to design the top rollers 9 as so-called twin pressure rollers. In the case of these twin pressure rollers, two top rollers 9 are each arranged stationary on a joint non-moving axle and are pressed together against the bottom roller 6. The guiding table 15 can be designed in such a way that it extends over a number of bottom aprons 12. The length of the deflecting roller 16 is hereby advantageously selected in such a way that it corresponds approximately to the width of the bottom apron 12. This makes it possible to design the leading edge 23 of the guiding table 15 between two deflecting rollers 16 in such a way that the cradle spacer of two top rollers 7 designed as a twin pressure roller can be supported in the known way. The device 14 according to the present invention for guiding bottom aprons 12 can thus in an advantageous way be applied in conjunction with standard components for top aprons 13. CLAIMS 1. A device (14) for guiding a bottom apron (12) in drafting units for drafting fibre strands (1), which device (14) comprises a guiding table (15) for the bottom apron (12), a rotatable deflecting roller (16) for the bottom apron (12) and a bearing arrangement for the deflecting roller (16), characterized in that the bearing arrangement for the deflecting roller (16) comprises a radial (17) and an axial (20) bearing, and that the deflecting roller (16) is supported by means of the radial and axial bearing (17, 20) in the guiding table (15). 2. A device for guiding a bottom apron according to claim 1, characterized in that the radial bearing (17) comprises means (18) for preventing the deflecting roller (16) from falling out. 3. A device for guiding a bottom apron according to claim 2, characterized in that the means (18) for preventing the deflecting roller (16) from falling out comprise at least one magnet (19). 4. A device for guiding a bottom apron according to any one of the claims 1 to 3, characterized in that the axial bearing (20) comprises at least one convex- shaped surface (21). A device for guiding a bottom apron in drafting units for drafting fibre strands comprises a guiding table for the bottom apron, a rotatable deflecting roller for the bottom apron and a bearing arrangement for the deflecting roller. The bearing arrangement comprises a radial and an axial bearing. The deflecting roller is held in the guiding table by the radial and the axial bearing. The radial bearing can comprise means, for example a magnet, for preventing the deflecting roller from falling out.

Documents:

00714-kol-2006-abstract.pdf

00714-kol-2006-assignment.pdf

00714-kol-2006-claims.pdf

00714-kol-2006-correspondence others.pdf

00714-kol-2006-correspondence-1.1.pdf

00714-kol-2006-description(complete).pdf

00714-kol-2006-drawings.pdf

00714-kol-2006-form-1.pdf

00714-kol-2006-form-2.pdf

00714-kol-2006-form-26.pdf

00714-kol-2006-form-3.pdf

00714-kol-2006-form-5.pdf

00714-kol-2006-priority document.pdf

714-KOL-2006-(10-10-2012)-ABSTRACT.pdf

714-KOL-2006-(10-10-2012)-CLAIMS.pdf

714-KOL-2006-(10-10-2012)-CORRESPONDENCE.pdf

714-KOL-2006-(10-10-2012)-DESCRIPTION (COMPLETE).pdf

714-KOL-2006-(10-10-2012)-DRAWINGS.pdf

714-KOL-2006-(10-10-2012)-FORM-1.pdf

714-KOL-2006-(10-10-2012)-FORM-2.pdf

714-KOL-2006-(10-10-2012)-OTHERS.pdf

714-KOL-2006-(10-10-2012)-PA.pdf

714-KOL-2006-(10-10-2012)-PETITION UNDER RULE 137.pdf

714-KOL-2006-(24-08-2012)-ANNEXURE TO FORM 3.pdf

714-KOL-2006-(24-08-2012)-CORRESPONDENCE.pdf

714-KOL-2006-CORRESPONDENCE 1.1.pdf

714-kol-2006-form 18.pdf

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