Yarn tension control apparatus

Yarn tensioning apparatus for tensioning yarns, comprising an electronically controlled yarn tensioning device including an electromagnet core and coil assembly to be located along a yarn path and including a rigid core structure having core faces defining a gap therebetween located in a single vertical plane immediately adjacent and facing the associated yarn path, a yarn wear surface assembly of a pair of adjacent confronting wear surface members in parallel vertical planes immediately alongside said core faces and spanning the gap providing confronting substantially flat vertical yarn contacting wear surfaces between which the yarn passes in frictical contact with such surfaces, the outer wear surface member fartherest from the core structure being of magnetic material to respond to variable magnetic attractive forces of the flux passing through the core structure to vary the force of attraction thereon inwardly horizontally toward the core structure and thereby vary tension of the yarn leaving the device and the other wear surface member of said pair being movable responsive to yarn feed movement of the yarn engaged thereby, electronic control circuit means electrically coupled to the electromagnet coil for regulating a control voltage applied to the coil and thereby regulating the magnetic forces exerted on the wear surface members, and surface displacing means for continuously moving one of said wear surface members in a predetermined path alongside the yarn path to continuously change the portion of the wear surface thereof engaging the yarn including means moving in coordinated relation to said one wear surface member to limit movement of the other wear surface member to generally corresponding movement.

Yarn tensioning apparatus for tensioning yarns, comprising an electronically controlled yarn tensioning device including an electromagnet core and coil assembly to be located along a yarn path and including a rigid core structure having core faces defining a gap therebetween located in a single vertical plane immediately adjacent and facing the associated yarn path, a yarn wear surface assembly of a pair of adjacent confronting wear surface members in parallel vertical planes immediately alongside said core faces and spanning the gap providing confronting substantially flat vertical yarn contacting wear surfaces between which the yarn passes in frictional contact with such surfaces, the outer wear surface member fartherest from the core structure being of magnetic material to respond to variable magnetic attractive forces of the flux passing through the core structure to vary the force of attraction thereon inwardly horizontally toward the core structure and thereby vary tension of the yarn leaving the device, electronic control circuit means electrically coupled to the electromagnet coil for regulating a control voltage applied to the coil and thereby regulating the magnetic forces exerted on the wear surface members, including a manually adjustable tension setting potentiometer and means responsive thereto for providing at variable voltage levels the said control voltage to said coil, and degaussing circuit means for intermittently applying negative going pulses which descend to a predetermined negative voltage level to said coil during adjustment of the tension setting potentiometer in a descending voltage direction to thereby supply to the coil periodic voltage pulses descending to a negative voltage level minimizing residual magnetic effects in said core structure of the tensioning device.

Yarn tensioning apparatus for tensioning a plurality of yarns being drawn from supply packages along plural yarn paths for delivery to yarn utilization apparatus such as beamers, knitting machines and the like, comprising a plurality of electronically controlled yarn tensioning devices forming a single channel of such devices regulated by a channel control voltage on a master output lead, each tensioning device comprising an electromagnet core and coil assembly to be located along each respective yarn path and including a rigid core structure defining a gap and having a pair of flat lateral mounting faces located in a single vertical plane immediately adjacent and facing the associated yarn path, a yarn wear surface assembly of a pair of adjacent confronting wear surface members formed of first and second confronting discs supported for rotation about a shaft forming a common center axis for the discs in parallel vertical planes immediately alongside said mounting faces and spanning the gap providing confronting substantially flat vertical yarn contacting wear surfaces between which the yarn passes in frictional contact with such surfaces, the outer wear surface member fartherest from the core structure being of magnetic material to respond to variable magnetic attractive forces of the flux passing through the core structure to vary the force of attraction thereon inwardly horizontally toward the core structure and thereby vary tension of the yarn leaving the device, electronic control circuit means remote from the yarn tensioning devices of said channel and electrically coupled through said master output lead to each of the electromagnet coils thereof for regulating the channel control voltage applied to the coils and thereby regulating the magnetic forces exerted on the wear surface members, and surface displacing means including a motor having a rotary output coupled to the first disc to continuously rotate the same in a predetermined path alongside the yarn path to continuously change the portion of the wear surface thereof engaging the yarn and means extending from said shaft for restraining rotation of the second disc to substantial conformity to the rotation of said first disc.