Winding – tensioning – or guiding – Coil holder or support – Spool or core
Patent
1994-05-17
1996-10-01
Mansen, Michael R.
Winding, tensioning, or guiding
Coil holder or support
Spool or core
139452, B65H 5100, D03D 4736
Patent
active
055605567
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a yarn feeder and, more particularly, to a yarn feeder having a yarn storage body which is rotatably supported by a rotating shaft and is held stationary as the shaft rotates by mutually oriented magnets mounted on the storage body and a housing.
BACKGROUND OF THE INVENTION
In view of the fact that the yarn is supplied to the storage body of a yarn feeder from one side, is deposited in turns on said storage body and is then, in most cases overhead and in a circulatory movement, removed on the other side, the storage body must be supported rotatably on the drive shaft of a yarn winding member and it must be prevented in a contactless manner from rotating together therewith. An eccentric weight provided on the storage body and acting through the force of gravity can, for example, be used as a means for preventing the storage body from rotating. In practice, however, the measure of arranging mutually oriented holding magnets in the housing and in the storage body has become generally accepted, said holding magnets guaranteeing, thanks to magnetic forces, that the storage body is prevented from rotating. The holding magnets have, however, the disadvantage that the smallest force preventing the storage body from rotating will occur when the holding magnets are fully aligned with each other, whereas said force will increase progressively in response to a relative rotational displacement of the storage body. Within the large speed range of the drive shaft, resonance phenomena will occur, and these resonance phenomena will result in rotary oscillation movements of the storage body about the axis of the shaft. These oscillation movements are extremely disadvantageous when the machine is in operation, especially if the amplitude at the external circumference touched by the turns of the yarn increases to 1.5 mm or to an even higher value.
There is the risk that the turns will no longer be transported properly to the unwinding side, that sensors directed onto the turns will not respond in an adequate manner and that heavy wear and damage will result from the forces of gravity. In the case of socalled measuring weft feeders comprising at least one stopping device which acts on the storage body by means of a stopping element at certain intervals for blocking then drawing off of the yarn, the rotary oscillation movements will result in detrimental forces acting on the stopping element. Moreover, the response behaviour of a yarn sensor, which is integrated in the stopping device in most cases, will be impaired by said rotary oscillation movements. Finally, in the case of yarn feeders operating according to the socalled yarn separation principle, the mass of the storage body is comparatively big because of the components in the storage body which are required for the yarn separation process, and this will tend to generate large amplitudes of the rotary oscillation movements and, possibly, detrimental forces of gravity. Since a mechanical access to the storage body from the side of the stationary housing for the purpose of supporting the storage body against these oscillation movements is impossible due to the movements of the yarn, it has, up to now, been unavoidable to put up with said oscillation movements.
It is true that, in the case of a measuring weft feeder provided with a wobbling ring which is arranged behind the yarn supply and which is used as an advance element of the storage body, it is known to use the wobbling movement for touching the wobbling ring periodically from outside by means of a pressure bow so as to interfere with the generation of rotary oscillation movements of the storage body. This principle is, however, bound to the use of a wobbling ring.
It is also known to provide the storage body with an extremely small and light structural design and to arrange a very large number of holding magnets also within the storage body for suppressing the rotary oscillations by very high magnetic forces. Extremely small storage bodies will, however, resu
REFERENCES:
patent: 4785855 (1988-11-01), Benz et al.
patent: 4926912 (1990-05-01), Zenoni
patent: 5294067 (1994-03-01), Tholander et al.
patent: 5310127 (1994-05-01), Deiuri
Claesson Tore
Koskelainen Morgan
Iro AB
Mansen Michael R.
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