Yarn-feeding assembly for textile machines

Abstract

A first yarn feeder is provided with a drum which has a plurality of yarn loops wound thereon and is driven to rotate by a respective motor. The motor is electronically connected to a textile machine for rotating at a speed proportional to the yarn-drawing speed of the textile machine and delivering the yarn wound on the drum to the latter. A second feeder is arranged to draw the yarn from a reel and to deliver it to the first feeder, with a delivery action which is modulated by a control loop. The latter is programmed to stabilize the tension of the yarn unwinding from the second feeder on a predetermined value on the basis of a signal received from a tension sensor operatively coupled to the yarn.

What is claimed is: 
     
         1 . A yarn-feeding assembly, comprising a first yarn feeder provided with a drum which has a plurality of yarn loops wound thereon and is driven to rotate by a respective motor, said motor being electronically connected to a textile machine for rotating at a speed proportional to the yarn-drawing speed of said textile machine and delivering the yarn wound on the drum to the textile machine, and further comprising a second feeder, which is arranged to draw the yarn from a reel and to deliver it to said first feeder, with a delivery action which is modulated by a control loop which is programmed to stabilize the tension of the yarn unwinding from said second feeder on a predetermined value on the basis of a signal received from a tension sensor operatively coupled to the yarn. 
     
     
         2 . The yarn-feeding assembly of  claim 1 , wherein said tension sensor is arranged between said first feeder and said second feeder. 
     
     
         3 . The yarn-feeding assembly of  claim 1 , wherein said second feeder is provided with a drum driven to rotate by a respective motor, and said control loop is programmed to modulate the speed of rotation of said drum of the second feeder in such a way as to maintain the tension of the unwinding yarn substantially constant on said predetermined value. 
     
     
         4 . The yarn-feeding assembly of  claim 3 , wherein said first feeder and said second feeder are integrated in a single housing and their respective motors share the same control circuit. 
     
     
         5 . The yarn-feeding assembly of  claim 1 , wherein said second feeder is provided with a stationary drum having a plurality of loops of yarn coming from said reel wound thereon, and with braking means controlled by said control loop for applying a modulated braking action to the unwinding yarn in such a way as to maintain the yarn tension substantially constant on said predetermined value. 
     
     
         6 . The yarn-feeding assembly of  claim 5 , wherein said braking means comprise a hollow, frustoconical braking member which is biased with its inner surface against the delivery edge of said stationary drum by driving means operatively connected to said control loop.