Method and improved yarn feeder system and device for optimising yarn feed to a textile machine operating highly discontinuously or with alternating motion

Abstract

Method and system using a device for feeding yarn to a textile machine, operating discontinuously or with alternating motion, and a device compensating for changes in conditions for feeding or taking up yarn by the textile machine, the compensator device including a movable compensator that performs this compensation to maintain constant yarn tension even when conditions for feeding or taking up yarn change, the movable compensator being rigid and connected to an electric actuator, a control unit of this actuator capable of detecting displacement of the movable compensator from a predetermined resting position when there is a change in take-up or feeding of the yarn and capable of returning the movable compensator to the resting position after such change. Provision is made for continuously detecting yarn tension and operating the electric actuator to maintain tension constant. The compensator device used in this system operating according to the method.

1 . A method for feeding yarns or threads including metal wires to a textile machine at a constant tension, or to a machine processing the metal wire, said feeding taking place discontinuously, that is with sequences of stages in which the yarn moves with at least a first and at least a second condition of feeding or take-up by the machine which differ from each other, said conditions following each other in time, comprising:
 said feeding being performed by a yarn feeder device having   tension detection means,   yarn accumulator means driven by its own electric motor, and   control means connected to such tension detection means and accumulator means and capable of acting on such accumulator means on the basis of a tension value obtained from said tension detection means,   provision being made for a compensator device associated with said feeder device acting together with the yarn coming from said accumulator means before acting together with said tension detection means,   said compensator device being able to compensate for changes in the feed or take-up conditions of the yarn at the transition between each first and each second feed or take-up condition following upon the first, this enabling the control means for the feeder device to act on the accumulator means to alter action by the accumulator means on the yarn and maintain the value of the tension detected by the tension detection means constant over time and equal to a set value,   said constant tension also being maintained during the stage of changing the feed conditions due to the interaction between said yarn and said compensator device,   the compensator device including the movable compensating means supporting a body capable of acting together with the yarn at one free end, said movable compensating means being able to move from a predetermined resting position in the feed direction of yarn when the yarn passes from a condition of lesser take-up to a condition of greater take-up, but moving in the opposite direction when the yarn passes from a condition of greater take-up to a condition of lesser take-up, said compensating means returning to the resting position at the end of such change in take-up,   wherein provision is made to control the movement of said compensating means through its own corresponding electric motor directly and rigidly attached to said compensating means and capable of directly controlling the movement of a compensating arm of said compensating means, the compensating arm being controlled according to the set or detected tension of the yarn and the position measured during each stage in which it is fed to the textile machine, said compensating means being rigid.   
     
     
         2 . The method according to  claim 1 , wherein the compensating means and its electric motor that controls the compensating means directly and strictly in movement operate in a passive-dynamic mode, said compensating means being able to move freely, together with the motor, under the force of the yarn but being brought back to the resting position after such movement by the electric motor, said motor generating a torque capable of maintaining said compensating means for yarn in the resting position as yarn is fed to the textile machine. 
     
     
         3 . The method according to  claim 1 , wherein the compensating means and the relative electric motor which controls it in motion operate in an active-predictive mode, said motor moving the compensating means from the resting position to a compensating position corresponding to change in the tension of yarn as soon as such change is detected. 
     
     
         4 . The method according to  claim 1 , wherein it provides for continuous control of the electric motor of the compensator device by a control unit connected directly or indirectly to the tension detection means. 
     
     
         5 . The method according to  claim 1 , wherein provision is alternatively made for said compensating means to rotate about a fixed axis of a drive shaft leaving the electric motor to which said compensating means is rigidly attached, or moves along the compensator device. 
     
     
         6 . The method according to  claim 1 , wherein provision is made for a further accumulation of yarn on the compensator device in addition to the accumulation of yarn on the accumulator means of the feeder device. 
     
     
         7 . The method according to  claim 1 , wherein movement of the compensating means is alternatively angularly limited or unlimited. 
     
     
         8 . A system for feeding yarn, including metal wires or threads, at constant tension to a textile machine or to a metal wire processing machine, said feeding being performed discontinuously or with sequences of stages in which the yarn moves with at least a first and at least a second condition of feeding or take-up by the machine which differ from each other, said conditions following one another in time, said feeding system operating according to the method in  claim 1  and including
 a feeder device for the yarn having tension detection means, 
 yarn accumulator means driven by its own electric motor and 
 control means connected to such tension detection means and accumulator means and capable of acting on said accumulator yarn on the basis of a tension obtained from such tension detection means, 
 provision being made for a compensator device associated with said feeder device acting together with the yarn leaving said accumulator means before it acts together with said tension detection means, 
 said compensator device being able to compensate for changes in the feeding or take-up conditions for the yarn at the transition between each first and each second feeding or take-up condition consecutive upon the first, this enabling the control means for the feeder device to act on the accumulator means to alter their action on the yarn and maintain the value of the tension detected by the tension detection means constant over time and equal to a set value, said constant tension being maintained even during the stages of changes in the feeding conditions thanks to the interaction between said yarn and said compensator device, 
 the compensator device including movable compensating means capable of moving from a predetermined resting position in the feed direction for the yarn when the yarn passes from a condition of lesser take-up by the machine to a condition of greater take-up, but moving in the opposite direction when the yarn passes from a condition of greater take-up to a condition of lesser take-up, said compensating means returning to the resting position at the end of this change in take-up, 
 wherein said compensating means comprises a rigid arm carrying a terminal body able to act together with the yarn, said rigid arm being directly and rigidly connected to its own electric motor which directly controls it in movement according to the set or detected tension in the yarn, said rigid arm being located between said yarn accumulator means and said tension detection means, but being separate from the latter. 
 
     
     
         9 . The system according to  claim 8 , wherein alternatively the resting position of the compensating means lies within a range of movement of such compensating means having two limiting positions or is defined within a circular path of such means about an axis, said path not being restricted angularly. 
     
     
         10 . The system according to  claim 8 , wherein position detector means are provided to determine the spatial position of the rigid arm, said position detector means being associated with the drive shaft of said electric motor also rigidly carrying said rigid arm. 
     
     
         11 . The system according to  claim 10 , wherein provision is made for a control unit for the electric motor of the compensator device connected to the position detector means and capable of detecting movement of the compensating means from the predetermined resting position through said position detector means and of returning said compensating means to the predetermined resting position through control of the electric motor to which the compensating means is rigidly and directly attached, said control unit being directly or indirectly connected to the yarn tension detection means, said control unit controlling the electric motor on the basis of the tension in the yarn detected while said yarn is fed to the machine. 
     
     
         12 . The system according to  claim 11 , wherein said control unit is alternatively associated with the compensator device and connected to the control means of the feeder device or said control unit is part of the control means for the feeder device. 
     
     
         13 . The system according to  claim 8 , wherein said compensator device is a component independent of the feeder device, said compensator device being removably attached to the feeder device and being located at one end or on one side of said feeder device, said compensator device being fully automatic with respect to said feeder device but being intimately connected to said feeder device when it is connected to it. 
     
     
         14 . The system according to  claim 8 , wherein the compensator device has means rotating about its own axis and capable of receiving, when wound, the yarn in at least one of said machine feeding or take-up conditions. 
     
     
         15 . A compensator device suitable for use with a feeder device for yarns including metal wires or threads, at a constant tension to a textile machine or to a wire processing machine, said machine operating discontinuously,
 said compensator device adapted and configured for being part of the feeding system according to  claim 8 ,   said compensator device having movable compensating means capable of acting together with said yarn before it leaves said feeder device,   said compensating means being defined by a rigid arm rigidly associated with means for actuating its movement, said rigid arm acting together movably with the yarn,   the rigid arm being able to move from a predetermined resting position in the feed direction of the yarn when the yarn passes from a condition of lesser take-up by the machine to a condition of greater take-up, but moving in the opposite direction when the yarn passes from a condition of greater take-up to a condition of lesser take-up, provision being made for position detector means capable of detecting movement from said resting position, said position detector means being connected to a control unit capable of directly or indirectly detecting the tension in the yarn and to control said actuator means on the basis of the set or detected tension to return said rigid arm to the resting position after the movement therefrom, wherein the compensator is an independent device in comparison with the feeder device and is located on a side of said feeder device.   
     
     
         16 . The compensator device according to  claim 15 , wherein it comprises a rotating means capable of receiving the yarn upon it when the machine is stopped or when in the stage of returning the yarn to the feeding process. 
     
     
         17 . The compensator device according to  claim 15 , wherein the means for actuating the movement of the rigid arm are an electric motor, the electric motor being directly connected to said rigid arm through its drive shaft so as to rapidly compensating for any rapid movement of the arm, the arm being freely rotatable about an axis of the drive shaft when drawn by the yarn and being returned to the resting position through the action of the electric motor. 
     
     
         18 . The compensator device according to  claim 15 , wherein the means for actuating the movement of the rigid arm are an electric motor of very low inertia, the electric motor being directly connected to said rigid arm through its drive shaft so as to rapidly compensating for any rapid movement of the arm, the arm being freely rotatable about an axis of the drive shaft when drawn by the yarn and being returned to the resting position through the action of the electric motor.