Yarn-feeding/recovering method for textile machines, and apparatus for carrying out such method

Abstract

A textile machine receives yarn from a yarn-feeding device via a yarn-recovering device provided with a motorized reel having a passage for the yarn, which extends between an inlet port open to the middle of the free end of the reel and an outlet port formed on the lateral surface of the reel; the tension of the yarn being maintained constant on a reference value by adjusting elements, on the basis of a measured tension signal generated by a sensor; a consumption indicator being obtained to detect an interruption in the delivery of yarn, the adjusting elements being temporarily disabled and the yarn-recovering device being temporarily enabled to rotate at a speed modulated on the basis of the measured tension signal for maintaining the tension of the yarn constant on the reference value, if an interruption in the delivery of yarn is detected.

What is claimed is: 
     
         1 . A yarn-feeding/recovering method for textile machines, in which a textile machine receives yarn from a yarn-feeding device via a yarn-recovering device provided with a motorized reel having a passage defined therein which is passed through by the yarn and extends between an inlet port open to the middle of the free end of the reel and an outlet port formed on the lateral surface of the reel, said yarn-recovering device being operable for temporarily recovering an amount of yarn already delivered to the machine and for giving it back at a later time, and in which the tension of the yarn, with said reel in a position of minimum interference with the yarn, is maintained substantially constant on a reference value by adjusting means on the basis of a measured tension signal generated by sensor means, wherein it includes the following steps: obtaining a consumption indicator, which is indicative of the delivery of yarn from said yarn-feeding device and is independent from any operative signals from said textile machine and, if said consumption indicator indicates an interruption in the delivery of yarn, temporarily disabling said adjusting means and temporarily enabling said yarn-recovering device to rotate at a speed modulated on the basis of said measured tension signal for maintaining the tension of the yarn substantially constant on said reference value, the yarn-feeding device being provided with a stationary yarn-winding drum, from which the yarn is unwound upon request from the textile machine, and said adjusting means includes an electronic yarn-braking device arranged downstream of said yarn-feeding device and controlled by a control unit, and in which the withdrawal of yarn from said stationary drum is monitored by sensor means, wherein said consumption indicator further includes of a consumption signal based on the signals generated by said sensor means. 
     
     
         2 . The method of  claim 1 , further including the steps of monitoring the position of said reel with respect to said position of minimum interference with the yarn and, if said consumption signal indicates that yarn is withdrawn while said yarn-recovering device is enabled, automatically moving said reel to its position of minimum interference, disabling said yarn-recovering device, and re-enabling said adjusting means.