Winding – tensioning – or guiding – Tension control or brake – Supply controlled
Reexamination Certificate
2002-05-07
2004-03-09
Matecki, Kathy (Department: 3654)
Winding, tensioning, or guiding
Tension control or brake
Supply controlled
C188S267200, C242S15500M
Reexamination Certificate
active
06702221
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a tensioning system for controlling tension in a bobbin assembly and, more particularly, to the use of a magnetic responsive fluid to adjust the amount of tension associated with the bobbin.
BACKGROUND OF THE INVENTION
A tensioning system in which a bobbin is used to receive or deliver yarn should allow the bobbin to “take up” or “let out” yarn in a manner in which yarn tension is controlled. The bobbin usually supports yarn on a shaft that rotates to receive or deliver the yarn. During the rotation of the bobbin, variability in tension load or in the moment of inertia associated with the bobbin and yarn may develop and create undesired conditions of yarn movement. Control of yarn tension mitigates variable conditions and eliminates the need to form design margins for material variations that occur because of uncontrolled changes in the tension load and moment of inertia.
Systems and methods to control yarn tension traditionally utilize a weight that is attached to the yarn material or a friction clutch through which the yarn passes. However, the weight causes abrasions and does not adjust for irregular bobbin tension. Other systems and methods to adjust yarn tension use a friction clutch through which the yarn passes, but which may damage the yarn. Yet other systems and methods to change yarn tension use an electromagnetic tensioning device designed for yarn that is wrapped around a bell housing and provides a drag on the yarn. As a result, slippage and a loss of tension are possible. A system and method is therefore desired which will control yarn tension and overcome the problems of yarn overloading due to variability in the bobbin and yarn system load and variable moment of inertia.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for controlling the tension in a bobbin assembly having a supply bobbin with yarn wrapped thereon. The yarn is fed to a drive bobbin. A device is coupled to the supply bobbin and rotates as the yarn is fed to the drive bobbin. Magnetorheological fluid is in fluid contact with at least a part of the device. A variable magnetic field generator supplies a magnetic field to the magnetorheological fluid. Thus, resistance is applied to the device as it rotates with the supply bobbin. As a result, tension on the yarn is controlled.
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Haber David S.
Shtarkman Emil M.
Harness & Dickey & Pierce P.L.C.
Langdon Evan
Matecki Kathy
Northrop Grumman Corporation
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