Device and method to control yarn tension and yarn feeder
AssigneeIro AB
InventorsMario Gallo, Giovanni Toso
Life of this patent
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Abstract
A device for controlling the tension of a yarn includes a gauge measuring tension of the yarn and optionally a brake driven by the tension gauge to vary braking of the yarn. The gauge comprises electromagnetic control means having a moveable control element subject to a force dependent on the tension of the yarn, and a control circuit. The latter circuit supplies the electromagnetic control means with a current so that the moveable control element remains virtually still in a given position, during variations of the yarn tension. This current is indicative of the tension of the yarn and is measured to obtain a measure of the yarn tension. The device can be associated with a yarn feeder having a drum and moveable eyelet coaxial with the drum.
Claims28
A device for controlling tension of a yarn at the outlet of a yarn feeder provided with a drum about which a reserve of yarn windings are disposed for feeding the yarn into a weaving machine, said device comprising:
- an eyelet disposed coaxially with an axis defined by the drum for guiding the yarn along the drum axis towards the weaving machine as the yarn is drawn off of the reserve, said eyelet being movable along the drum axis and the yarn extending through the eyelet and exerting a first force thereon which is proportional to the yarn tension and which is oriented along the drum axis;
- and
- a yarn tension measuring arrangement including a control circuit, a position sensor, and an electromagnetic control to which current is supplied by said control circuit, said electromagnetic control having a movable control element operable electromagnetically and connected to said eyelet for movement therewith, said position sensor communicating with said control circuit and providing a signal thereto upon displacement of said movable control element from a predetermined measuring position and corresponding to displacement of said eyelet along the drum axis as a result of said first force, said control circuit providing said electromagnetic control with current in response to said signal from said position sensor such that said electromagnetic control generates a second force which moves said movable control element to balance said first force and maintain said movable control element substantially motionless in said predetermined measuring position during variations in the yarn tension, said tension measuring arrangement including means for measuring said current and generating a signal which corresponds to the yarn tension.
A method of measuring the tension of yarn at the outlet of a yarn feeder provided with a drum about which a reserve of yarn windings are disposed for feeding into a weaving machine, said method comprising:
- providing an eyelet coaxial with an axis defined by the drum and an electromagnetic control having a movable control element connected to the eyelet for movement therewith;
- drawing the yarn from the drum and through the eyelet and guiding the yarn along the drum axis towards the weaving machine whereby the yarn exerts a first force on the eyelet upon passing therethrough which is proportional to the yarn tension;
- displacing the eyelet and the movable control element along the drum axis from a predetermined measuring position with said first force;
- sensing a displacement of the movable control element from said predetermined measuring position and signalling a control circuit;
- supplying the electromagnetic control with current from the control circuit and generating a second force to move the movable control element in opposition to each displacement thereof from said predetermined measuring position as a result of said first force to maintain the movable control element substantially motionless in said predetermined measuring position during variations in yarn tension;
- and
- detecting the value of said current and generating a signal which corresponds to the yarn tension.
Dependencies are inferred from the claim text.