The invention relates to a yarn feeding device according to the preamble part of claim 1.

Yam feeding devices of such types operate, e.g. on weaving machines or knitting machines, for the purpose of an improved yarn control with yarn separation at the stationary storage body. This means that the yarn windings formed on the periphery of the storage body are conveyed in the direction towards the withdrawal end of the storage body and at the same time are separated from each other.

A yarn separation functional principle known in practice on a stationary storage body is based on a wobbling motion of the separation rod cage in relation to the supporting rod cage, which wobbling motion is generated by the rotating driving shaft. During the wobbling motion rods of the separation rod cage which are arranged between the rods of the supporting rod cage are tilted back and forth. These tilting motions at the same time are superimposed by alternating lifting movements and lowering movements of the rods of the separation rod cage. Each rod of the separation rod cage out of a lowered position gradually first moves outwardly between two rods of the supporting rod cage, while the same rod during the subsequent and opposite tilting movement is lowered between the adjacent rods of the supporting rod cage. These superimposed movements convey the yarn windings in withdrawal direction and at the same time separate the yarn windings from each other.

The separation rod cage bearing structure of a yarn feeding device as known in practice is formed as a cylinder surface on the periphery of a bearing bushing. The bearing bushing is arranged and fixed on an eccentric section of the driving shaft.

In another yarn feeding device as disclosed in EP 0 164 033 B1 a cylinder surface constitutes the separation rod cage bearing structure. The cylinder surface is formed by the periphery of an outer bushing which is rotatably provided on an inner bushing and which can be secured in different relative rotational positions on the inner bushing. The inner bushing in turn is seated on a section of the driving shaft. By a relative rotation between both bushings not only the extent of the yarn separation can be adjusted steplessly but also the yarn separation can be matched with the respective sense of the

rotation of the driving shaft such that for each sense of rotation the yarn windings will be conveyed by the same rods in the direction towards the withdrawal end of the storage body.

Employing one or two bushings which have to be machined very precisely means considerable effort in terms of manufacturing and assembling. Furthermore, complicated mechanisms are needed for the relative rotation between the bushings or of the bushing and for fixing the respective rotational position of a bushing. Moreover, the bushing or both bushings occupy significant mounting space in radial direction which might lead to out-of-balance problems when the driving shaft is rotating rapidly. The large space needed for mounting results in problems for the storage body construction because recently developed yarn feeding devices are significantly downsized.

It is an object of the invention to provide a yarn feeding device as mentioned which can be manufactured simpler and for fair cost, particularly to provide a yarn feeding device having a relatively small storage body for applications among others also at circular knitting machines which frequently have to be equipped with up to 48 or more yarn feeding devices such that a dimension of the yarn feeding devices which is as small as possible constitutes an important factor.

The object is achieved by the features of claim 1.

Since the separation rod cage bearing structure is formed integrally with the driving shaft a separate manufacture and assembly of one or several bushings are abolished. Furthermore, mounting space is saved in radial direction which is important in particular for small diameter storage bodies. At the same time a mechanism for the rotational adjustment and/or fixation of the bushing or the bushings is dispensed with. This results in a significant structural simplification of the yarn feeding device, in particular in the interior of the storage body, avoids out-of-balance problems and contributes to save weight.

In an expedient embodiment the separation rod cage bearing structure is formed as a cylinder surface on a free end of the driving shaft. However, the separation rod cage bearing structure does not need to be a cylindrical surface but instead may have another

geometrical configuration allowing to support a roller bearing or a plain bearing for rotatably supporting the separation rod cage. The respective bearing located on the drive shaft has to control the relative rotation between the drive shaft and the separation rod cage which is secured against a co-rotation with the drive shaft by the supporting rod cage when the drive shaft rotates. Forming the separation rod cage bearing structure at a free end of the drive shaft, furthermore, results in the advantage of a simple machining as the cylinder surface does not need to be machined between coaxial cylinder surfaces of the drive shaft which otherwise would form boundaries at both sides of the separation rod cage bearing structure.

In a preferred embodiment an eccentric annular shoulder is provided between the cylinder surface and an adjacent supporting rod cage bearing surface which is coaxial to the surface of the drive shaft. The annular shoulder is easy to manufacture and constitutes a retainer or stop for the rotary bearing of the separation rod cage.

In a further preferred embodiment a circumferential groove is provided between the annular shoulder and the cylinder surface. The circumferential groove as well results in advantages for the manufacture as it simplifies a proper machining of the entire cylinder surface.

The drive shaft, preferably, consists of steel and is machined by turning. At least some portions of the drive shaft even may be ground.

Expediently, the eccentricity and the inclination of the cylinder surface are offset in relation to each other in circumferential direction by a about 90°. In this fashion an optimally large magnitude of the separation of the yarn windings with harmonic wobbling motions of the rods of the separation rod cage in relation to the rods of the supporting rod cage is achieved even with a relatively small angle of inclination and a relatively small eccentricity of the cylinder surface.

An embodiment of the invention will be explained with the help of the drawing. In the drawing is:

Fig. 1 a perspective view of a yarn feeding device,

Fig. 2 a longitudinal section of the storage body of the yarn feeding device of Fig. 1 in the axis of a drive shaft,

Fig. 3 a horizontal in the section plane Ill-Ill in Fig. 2, and

Fig. 4 a further longitudinal section similar to Fig. 2 in simplified illustration.

A yarn feeding device F shown in Fig. 1 e.g. is a yarn feeding device for a knitting machine like a circular knitting machine. However, the yarn feeding device F as well may be implemented at other types of knitting machines and/or with the construction principle as described in the following even may be used at weaving machines or at other textile machines.

When used at knitting machines the yarn feeding device F e.g. has total longitudinal extension of only about 240 mm and a maximum lateral dimension of about 150 mm and a width of only about 80 mm. In this case the storage body indicated in Fig. 1 has an outer diameter of only about 60 mm. The drive shaft 10 shown in Figs 2 to 4 has a maximum diameter of only about 15 mm. Totally seen it is a relatively small dimensioned or downsized yarn feeding device F ₁ as is expedient for equipping circular knitting machines which operate with a plurality of such yarn feeding devices.

The yarn feeding device F in Fig. 1 has a housing 1 which contains a not shown drive motor and in which a drive shaft is rotatably supported which is driven for rotation by the drive motor. The drive shaft defines by its drive shaft axis X the axis of a storage body K which is rotatably supported on the drive shaft, however, is hindered against co-rotation with the rotating drive shaft by known means (stationary storage body K). In order to hinder the storage body K against co-rotation e.g. permanent magnets could be provided which in part are arranged in the storage body and in part in the housing and which are aligned with each other.

A winding disc 3 is firmly connected to the drive shaft which is not shown in Fig. 1. The winding disc 3 contains a winding eyelet 4.

The storage body K comprises a supporting rod cage 5 which is coaxial to the drive shaft and has substantially axially extending rods 6 which are separated in circumferential direction by interspaces 9, and a separation rod cage 7 which is received inside the supporting rod cage. The separation rod cage 7 has as well substantially axially extending rods 8 which are spaced apart in circumferential direction. The rods 8 are located in the interspaces 9 and are in circumferential direction dimensioned narrower than the interspaces 9.

The supporting surface formed by the rods 6 of the supporting rod cage 5 serves to support the yarn windings which are wound on side by side on the storage body K during the rotation of the winding disc 3 in relation to the storage body K. The rods 8 of the separation rod cage have the task of conveying the yarn windings which are supported on the supporting rod cage 5 in withdrawal direction forwards (axially away from the winding disc 3) and at the same time to separate the yarn windings from each other. For this purpose the separation rod cage 7 is driven in relation to the supporting rod cage 5 with a wobbling movement during which each rod 8 alternatingly is tilted in withdrawal direction and opposite to the withdrawal direction, and at the same time exits during the tilting movement in withdrawal direction gradually from the interspace 9 outwardly beyond the periphery formed by the rods 6 and which is lowered during the tilting movement opposite to the withdrawal direction gradually back between the two adjacent rods 6.

This wobbling movement of the separation rod cage 7 is induced by a separation rod cage bearing structure L provided at the drive shaft 10 shown in Figs 2 to 4. The separation rod cage bearing structure L is eccentric in relation to the axis X of the drive shaft (eccentricity E in Fig. 3), and is inclined (inclination S in Fig. 3) as well. The eccentricity E, e.g., is offset in circumferential direction in relation to the inclination S by 90°. This 90° offset is only a selected offset measure out of a plurality of different and possible magnitudes of the offset.

According to Figs 2 and 3 the rods 6 of the supporting rod cage 5 are secured to a hub part 11 which rotatably is supported with the help of a rotary bearing 12 (either a plain bearing assembly or a roller bearing assembly) on a supporting rod cage bearing surface 13 which is coaxial to the axis X of the drive shaft.

The separation rod cage 7 has an interior hub part 14 which is rotatably supported with the help of a rotary bearing 16 (a roller bearing assembly or a plain bearing assembly) on the separation rod cage bearing structure L. In the shown embodiment the separation rod cage bearing structure L is a cylinder surface 17 formed at a free end 15 of the drive shaft 10 and integrally with the drive shaft 10. The cylinder surface 17, e.g. is machined by turning and/or grinding. The axis Y of the cylinder surface 17 is inclined obliquely in relation to the axis X of the drive shaft, and, in addition, is provided eccentrically in relation to the axis X of the drive shaft.

Fig. 2 shows clearly that the rod 8 shown on the right side is displaced outwardly in relation to the adjacent rods 6, while the rod 8 shown on the left side is set back in relation to the rods 6.

The cross-sectional view in Fig. 3 in section plane Ill-Ill in Fig. 2 shows that the rod 8 located at the extreme right position is displaced outwardly with a maximum magnitude in relation to the two adjacent rods 6, while the rod 8 located at the extreme left position is pulled back between the adjacent rods 6. This results in the effect that during the forward tilting movement of each rod 8 in withdrawal direction (in Fig. 2 downwardly) this rod 8 gradually will exit outwardly between the two adjacent rods 6 and will lift the yarn windings outwardly from the rods 6 and will convey the yam windings in withdrawal direction before the rod 8 during the subsequent tilting movement which is oriented into opposite direction and while the rod 8 at the same time is lowered between the two adjacent rods 6 again deposits the yarn windings on the rods 6. In this fashion all of the yarn windings will be conveyed in withdrawal direction and at the same time will be separated from each other.

Fig. 4 illustrates in a simplified view the rotary bearing of the separation rod cage 7 on the separation rod cage bearing structure L, e.g. on the cylinder surface 17. Fig. 4 also indicates the eccentricity and the inclination of the cylinder surface 17 in relation to the axis X of the drive shaft. The axis Y of the cylinder surface 17, so to speak, is positioned askew in space in relation to the axis X of the drive shaft.

An eccentric annular shoulder 18 is formed in the drive shaft 10 between the cylinder surface 17 and the bearing surface 13. A circumferential groove 19 is machined between the annular shoulder 18 and cylinder surface 17. The free end 15 of the drive shaft 10 is formed with a threaded bore for a not shown fastening element.

The separation rod cage bearing structure L of the described embodiment is integrally formed at the free end 15 of the drive shaft 10. In case of a not shown alternative, however, the separation rod cage bearing structure L e.g. could be provided at the shown location of the bearing surface 13, such that then the bearing surface 13 will be located at the free end 15. The separation rod cage bearing structure L does not need to be in any case a cylinder surface 17 but instead could have another geometrical configuration which allows to properly mount a rotary bearing (plain bearing or roller bearing).

Due to the shown 90° offset between the eccentricity E and the inclination S (Fig. 3) it is necessary to drive the drive shaft 10 with a certain predetermined direction of the rotation in order to achieve the conveying movement and the yarn separation in withdrawal direction. In the case that the yam feeding device should be driven in the opposite direction of rotation, the drive shaft 10 has to be substituted by another drive shaft which has a correspondingly inverted separation rod cage bearing structure. Alternatively, the offset between the eccentricity and the inclination S could be selected such that a yarn separation and a conveying action correctly will result in withdrawal direction irrespective of the sense of the rotation.

The drive shaft 10, expediently, is made from steel and is at least machined by turning, preferably, at least in some sections by grinding. The integrated arrangement of the cylinder surface 17 at the free end 15 simplifies the shaping of the cylinder 17, because there is good access for a machining tool to the free end 15. Alternatively, the drive shaft 10 may be forged or pressed.