FIELD OF THE INVENTION
The present invention relates to the improvements in textile spindle assemblies and in particular to an apparatus of the type in which the spindle blade is supported by air foil bearings and magnetic bearings for effective supporting of the spindle blade and the associated structure.
BACKGROUND OF THE INVENTION
Spindle used in a ring spinning and twisting machine, comprises a spindle blade assembled in the conical part of upper part of the spindle which is rotatably supported in the bottom part and driven by the drive system of the ring spinning and twisting machine. The spindle blade is rotatably supported by a neck bearing and a foot bearing. The neck bearing is positioned in a tube-like inner housing which is pressed at the top portion of the outer housing. The bottom portion of the outer housing is closed and so designed that it can be fitted on the spindle rail and vertically aligned.
The foot bearing comprises a radial bush bearing provided to take the radial force and an axial foot bearing to take up the axial force which are generated due to the rotation of the upper part of the spindle. The bottom portion of the spindle blade is disposed on the axial foot bearing. The radial bush bearing is fitted to a centering sleeve and the centering sleeve carrying the radial bush bearing is fitted to the neck bearing housing at its bottom side. The centering sleeve is provided with annular helical grooves. Between the annular outer contour of the centering sleeve and the hollow cylindrical inner contour of the outer housing the oil spool is placed vertically. The oil spool is retained in its required position by means of a spacer. The annular helical grooves provided on the centering sleeve provides an orbital variable spring action to the centering sleeve which is transmitted to the oil spool for vibration damping.

Between the cylindrical outer contour of the centering sleeve and the hollow cylindrical inner contour of the outer housing there is a narrow damping gap which is filled with oil. The arrangement is so designed that the oil is also the lubricating oil in the area of the axial foot bearing and radial bush bearing.
In the spindles employed in the prior art, the spindle blade is supported at the neck portion by an anti friction bearing and the foot portion is supported by radial bush bearing and an axial foot bearing. This is liable to increase the friction and consequently liable to consume more power required to drive the spindle.
OBJECTS OFTHE INVENTION
It is an object of the invention to reduce the friction at the neck portion and the foot portion of the spindle.
It is an another object of the invention to reduce the power required to drive the spindle.
It is yet another object of the present invention to make a spindle of the above mentioned type in such a manner the vibration can be further reduced.
It is yet another object of the invention to provide an effective circulation and spill out of lubricating oil for better cooling of the system.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION
The foil bearings are characterized by a high temperature load capacity, and can also handle high mechanical loads. Foil bearing is an aerodynamic self-acting bearing which generates its own load supporting air film from the rotation of the shaft itself. It requires no external pressurization but utilizes the freely available ambient air. Foil air bearing is preferred to use for spindles because of its long life, reliability and its attractive weight reduction. Unlike the antifriction bearings air foil bearing requires no lubrication, other than the ambient air or process fluid.
The magnetic bearing is used either as neck or foot bearing comprises an inner ring and an outer ring and there is a gap in between. The said rings are permanent magnets and arranged as their poles repels each other. While the rotation of the shaft, the flux created in the gap between the two rings and the atmospheric air are worked as lubricant instead of oil.
According to the embodiment of the present invention, the spindle is provided with air foil bearing as neck bearing and magnetic bearing as radial foot bearing which can able to withstand high temperatures and dust tolerant. Since the anti friction bearing generates noise at speeds greater than 20,000rpm and gets heated up, the combination of foil bearing and magnetic bearing can replace very efficiently the existing anti friction bearings in a textile spindle. The spindle of present invention can be operated up to 36,000rpm with a smooth operation and without excessive vibrations.
The spindle of this invention can realize a high speed of rotation without producing any substantial vibration. The rigidity and damping power of the neck bearing can be appropriately selected to damp any detrimental

vibration effectively when the spindle is driven at a critical speed. The power loss can also be reduced due to reduced friction and lesser wear can be achieved. Noise due to friction also reduced by using the air foil and magnetic bearings in the spindle of the present invention.
Hence, it is a primary object of the present invention to provide an improved construction of textile spindle which is not associated with the aforementioned drawbacks and limitations of the prior art proposals.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG 1 is an axial sectional view of a spindle constructed according to one of the embodiments of the present invention.
FIG 2 is an enlarged partial sectional view of the neck bearing zone according to one of the embodiments of the present invention.
FIG 2 a is a is an enlarged partial sectional view of the neck bearing zone according to another embodiments of the present invention.
FIG 3 is a further enlarged partial sectional view of the neck bearing zone according to yet another embodiment of the present invention .
FIG 4 is a further enlarged partial sectional view of the foot bearing zone according to one of the embodiments of the present invention .
FIG 5 is an enlarged partial sectional view of the foot bearing zone according to one more embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS
The spindle assembly(SP) used in ring spinning and twisting machines comprises a top part(TP) and a bottom part(BP).
The top part(TP) comprises a spindle bearing shaft(7), a conical part(9) preferably made of light weight material such as aluminium and a wharve member(12). The conical part(9) is rigidly fitted to the upper end of the spindle bearing shaft(7). The spindle bearing shaft(7) of the top part(TP) is rotatably supported in a outer housing(6) of the bottom part(BP) The spindle insert assembly(1) is vertically assembled from the top into the outer housing(6) of bottom part(BP). The outer housing(6) assembled with the spindle insert assembly(1) forms the bottom part(BP) of the spindle(SP).
The outer housing(6) of the bottom part is fastened to a spindle rail which extends in a longitudinal direction of the machine. For this purpose, the spindle rail comprises at every spinning or twisting station a cylindrical bore, through which a respective spindle comprising the outer housing(6) is placed. An endless driven belt is provided for the purpose of driving the top part(TP) of the spindle. The endless driven belt tangentially drive the wharve member(12) and there by drive the top part(TP) of the spindle. The arrangement is such that the endless belt lies in the area above the upper bearing, which thus indirectly takes up the belt tension.
In an embodiments shown in figure-1, the upper portion of the spindle bearing shaft(7) is supported by an air foil bearing(2).
In addition to the above air foil bearing(2), a supporting cage(8a ,8b) is provided to minimize the belt tension acting over the air foil bearing and to enhance the initial stability at idle conditions and at slow speeds. The

supporting cage(8a ,8b) is positioned just below the air foil bearing(2) at the portion(8) shown in figurel. The air foil bearing(2) and the supporting cage(8a,8b) are fitted to the cylindrical inner counter of the inner housing(11). The cylindrical outer counter of the inner housing(11) is press fitted to the outer housing(6) of the bottom part(BP). The foil bearing and the supporting cage(8a ,8b) rotatably support the upper portion of the spindle bearing shaft(7).
In an embodiment shown in figure-2 the supporting cage(8a) is an antifriction bearing, for example ball bearing. In an embodiment shown in figure-2a , the supporting cage (8b) is a bush bearing.
In an embodiment shown in figure-3, the upper portion of the spindle bearing shaft(7) is supported by a magnetic bearing(23). The magnetic bearing(23) comprises an annual outer ring(23a) and an annular inner ring(23b) which are made up of permanent magnet. The inner ring(23b) is rigidly fitted to the cylindrical outer contour of the spindle bearing shaft(7) and the outer ring(23a) is rigidly is fitted to the cylindrical inner contour of the inner housing(11). The annular outer ring(23a) and the annular inner ring(23b) are arranged coaxial to each other with a small gap provided between them and their polarities being arranged such that magnetic force generated by them repel each other.
As shown from the figure 1, the spindle insert(1) is further provided with a centering sleeve(4), the upper portion of which is fitted to the housing(11). In the embodiment shown in figure-1, bottom portion of the spindle bearing shaft(7) is supported by a combination foot bearing(3) comprising radial foot bearing(3a) and an axial foot bearing(3b), which are arranged inside the bottom portion of the centering sleeve(4). While the radial foot bearing(3a) is disposed to take up the radial load, the axial foot bearing(3b) is disposed to take up the axial load of the spindle top part.

In an embodiment shown in figure-4, magnetic bearing(13) comprising an annular outer ring(13a) and an annular Inner ring(13b), both made up of permanent magnet is used to rotatably support the bottom portion of the spindle bearing shaft(7) of the top part(TP). The inner ring(13b) is being fitted to the outer contour of the spindle bearing shaft(7) at its lower portion and the outer ring(13a) being fitted to the cylindrical inner contour of the centering sleeve(4). The inner ring(13b) and the outer ring(13a) are arranged coaxial to each other with a small gap provided between them and their polarities arranged such that magnetic force generated by them repel each other.
In an embodiment shown in figure-5, the bottom portion of the spindle bearing shaft(7) of the top part(TP) is rotatably supported by the combination foot bearing(33) comprising air foil bearing(33a) and an axial foot bearing(3b) which are arranged inside of the bottom portion of the centering sleeve(4). While the air foil bearing(33a) is disposed to take up the radial load of the spindle top part, the axial foot bearing(3b) is disposed to take up the axial load of the spindle top part.
As shown in figure 1, at the bottom portion of the spindle between the cylindrical inner contour of the centering sleeve(4) and the cylindrical outer contour of the spindle bearing shaft(7) an annular gap is present which is filled with the lubricating oil. The lubricating oil being provided to lubricate both the foot bearing and the neck bearing in case the neck bearing is an antifriction bearing. The centering sleeve(4) having helically grooved slots which provide an orbital variable spring action.
The oil spool(5) is placed vertically at the annular gap between the inner contour of the outer housing(6) and the outer contour of the centering sleeve(4). The oil spool(5) is retained at a predetermined position by means of a spacer(10).
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The air foil bearings(2), (33a) work on the aero-dynamic principle by utilizing the atmospheric air as the working and lubricating medium. This minimizes the continuous frictional contact between spindle bearing shaft(7) and the bearing surface. Since air is used as the lubricating medium, the friction caused by the lubricating medium is eliminated.
Although the invention has been described and illustrated in detail with reference to certain embodiments, it is to be understood that the same is by way of illustration and example, and is not to be taken by way of limitation. The spirit and scope of the present invention are to be limited only by the terms of the appended claims.

WE CLAIM:
1. The textile spindle assembly provided with an improved bearing
arrangement comprises:
a rotatable spindle bearing shaft(7)
means provided to rotatably support the upper and the lower portion
of the spindle bearing shaft(7)
centering sleeve(4)
an outer housing(6)
wherein the means provided to support the upper portion and the
lower portion of the spindle bearing shaft(7) is an air foil
bearing(2,33a) and a magnetic bearing(13, 23 ).
2. Textile spindle assembly provided with an improved bearing arrangement according to claim 1, wherein the upper portion of the spindle bearing shaft(7) is supported by a magnetic bearing(23) and the lower portion of the spindle bearing shaft(7) is supported by an air foil bearing(33a).
3. Textile spindle assembly provided with an improved bearing arrangement according to claim 1, wherein the upper portion of the spindle bearing shaft(7) is supported by an air foil bearing(2) and the lower portion of the spindle bearing shaft(7) is supported by the magnetic bearing(13).
4. Textile spindle assembly provided with an improved bearing arrangement according to claim 1, wherein the upper portion of the spindle bearing shaft(7) is supported by a magnetic bearing(23) and the lower portion of the spindle bearing shaft(7) is supported by a combination foot bearing(3).
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5. Textile spindle assembly provided with an improved bearing arrangement
according to claim 1, wherein a supporting cage(8a) is arranged between
the airfoil bearing(2) and the inner housing(11).
6. Textile spindle assembly provided with an improved bearing arrangement according to claim 1, wherein the said supporting cage(8a) is an anti friction bearing.
7. Textile spindle assembly provided with an improved bearing arrangement according to claim 1, wherein the said supporting cage(8b) is a bush bearing.
8. Textile spindle assembly provided with an improved bearing arrangement
substantially as herein before described with reference to the
accompanying drawings.