Textiles: weaving – Weft manipulation – Weaving with stationary weft supply
Patent
1999-06-15
2000-10-03
Falik, Andy
Textiles: weaving
Weft manipulation
Weaving with stationary weft supply
2423654, B65H 5122, D03D 4736
Patent
active
06125892&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a device according to the preamble part of claim 1 and to a yarn feeding apparatus according to claim 16.
BACKGROUND OF THE INVENTION
In a device as known from PCT/EP94/00476 (WO 94/20402) the small diameter end region of the membrane is connected to the braking band such that the annular membrane extends outwardly from the large diameter edge of the braking band. When the annular membrane is displaced with its ring holder counter to the withdrawal direction of the yarn it undergoes a bending and pulling load from which the axial force load for the braking band results by which the braking band is pressed against the withdrawal surface. The annular membrane unifies in it the spring function for holding the braking band against the withdrawal surface and the function of a transmission body transmitting said axial force load from the ring holder to the braking band. In said arrangement, in practice, an irregular braking effect may occur for the yarn due to a misalignment between the braking band and the withdrawal surface along the essentially line-shaped contact zone between the braking band and the withdrawal surface. Moreover, the braking band is locally distorted counter to the withdrawal direction of the yarn in a yarn passage region when responding to the friction force and the repelling force of the yarn, said distortion hindering the achievement of a uniform tension level in the withdrawn yarn.
In other yarn feeding apparatuses (U.S. Pat. No. 5,409,043, U.S. Pat. No. 5,316,051), the axial force load is transmitted to the braking band by means of a hollow body having the shape of a frustocone into which the braking band is glued to the inner side of the hollow body. Said hollow body is supported at its outer side by means of a spring arrangement or an annular membrane which is elastic in the axial direction of the storage body, however, in the radial direction is relatively rigid. At the other side the hollow body is stiff in axial direction and elastic in the radial direction such that the flexible braking band is apt to deform locally in the yarn passage region and despite the axial force load. Said design requires multiple parts. The hollow body is highly loaded and tends to fatigue. The yarn feeding apparatus also consumes a large amount of space.
In another device known from DE-U-94 06 102, a plastic foam ring is glued to the outer side of the braking band which is held in the large diameter end of a rigid, frustoconical hollow body. A spring assembly engages at said hollow body which generates the axial force load for the braking band. Due to the relatively forceful spring assembly, the soft plastic foam ring is strongly deformed so that the inherent movability of the flexible braking band is restricted. The braking band bears onto a conical withdrawal surface of the storage body.
It is an object of the invention to create a device of the type disclosed above, as well as a yarn feeding apparatus in which along the contact zone between the braking band and the withdrawal surface, a uniform braking effect can be generated, and in which a substantially constant tension level can be maintained in the yarn being withdrawn.
This object can be achieved by providing a frusto-conical braking band oriented generally coaxially with the withdrawal surface defined on the storage body of a yarn feeding apparatus. An elastic annular membrane is connected at an outer end region thereof having the large diameter to a holding member, and an inner end region of the membrane having the small diameter is bent inwardly in a direction toward the withdrawal surface and is connected to the braking band.
The device saves space and consists of only two parts. Due to the bend of the small diameter end region of the annular membrane the braking band is no longer pulled against the withdrawal surface but is pushed against it. The braking band properly centers itself in operation thanks to the bend so that the braking effect along the contact zone remains uniform. It
REFERENCES:
patent: 5409043 (1995-04-01), Zenoni et al.
patent: 5738291 (1998-04-01), Tholander
patent: 5947403 (1999-09-01), Johansson et al.
Falik Andy
Iro AB
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