Winding – tensioning – or guiding – Unidirectional winding and unwinding – Variable number of windings on support
Patent
1999-08-16
2000-12-26
Walsh, Donald P.
Winding, tensioning, or guiding
Unidirectional winding and unwinding
Variable number of windings on support
139452, B65H 5120
Patent
active
06164580&
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a yarn feeding device and a yarn brake having a braking band situated in a large diameter end section of a braking band carrier and arranged substantially coaxially relative to the axis of a storage body of the yarn feeding device.
The braking band carrier, e.g. a Kevlar-frustocone jacket, of a yarn feeding device known from U.S. Pat. No. 5,316,051 is held at its small diameter end outer side by means of an annular membrane simultaneously constituting the spring assembly. Said annular membrane is fixed in the support which can be adjusted along a bracket of the yarn feeding device and transmits the axial pre-loading force for pressing the braking band against the withdrawal rim. Yarn brakes, as schematically shown in 051 are designed in practice such that the annular membrane is replaced by several star-like arranged tension springs. During use significant fluctuation of the spring properties or spring forces occur among the parallel acting tension springs, resulting in a deterioration of the centering effect. Misalignments of the braking band carrier in relation to the longitudinal axis of the storage drum occur as well as an irregular braking effect of the braking band along the circumference of the withdrawal rim of the storage body. Due to a force deflection of almost 90.degree. only a fraction of the spring force of the tension springs is used for generating the axial pre-loading force, so that an extremely high axial force has to be imparted on the tension springs.
WO 95/00431 discloses a yarn feeding device in which the braking band of the yarn brake is pulled by means of a conical, annular rubber membrane against the withdrawal rim. Said annular membrane is firmly secured at its large diameter end in a holder ring which is supported in the support via a Cardanic suspension having two Cardanic axes. Said Cardanic suspension is apt to assure an equilibrium position of the holder ring centered about the longitudinal axis of the storage body. However, since the spring assembly is integrated into the annular membrane, mis-positionings of the braking band can occur leading to an irregular braking effect along the circumference of the withdrawal rim. One reason for this is that said annular membrane cannot not be manufactured homogeneously enough to transmit uniformly in the circumferential direction the infinite number of force components defining in total said axial pre-loading force. Furthermore, local ageing influences even can enforce the negative effect of such inhomogenities. Since the annular membrane simultaneously operates as a bending spring and a tension spring, a significant part of the introduced axial force is dissipated by interior deformation work so that a relatively high axial force is needed.
In both known yarn feeding devices, the yarn brake with its spring assembly and the support of said spring assembly result in a bulky design obstructing access to the storage body.
Further prior art is contained in DE 9406102 U and DE 4407958 A. Intermediate literature is constituted by DE 19542045 A.
It is a task of the invention to create a yarn feeding device as well as a yarn brake of the kind as disclosed in which, despite a compact design of the yarn brake, a proper centering of the braking band on the yarn storing body as well as braking conditions which are the uniform in circumferential direction can be achieved and wherein in the force transmission from the support into the braking band as little force as possible is wasted.
Said task is achieved by providing a universal joint having a joint center which coincides with the axis of the storage drum to allow axial displacements of the carrier and tilting thereof.
Thanks to its joint center positioned on the storage body longitudinal axis, the universal joint is apt to assure an optimal and positive centering of the braking band on the withdrawal rim, since no significant elasticity in the lateral direction exists. Furthermore, the universal joint does allow tilting motions of the baking band carrier in all directio
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Ohlson Per
Tholander Lars Helge Gottfrid
Iro AB
Walsh Donald P.
Webb Collin A
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