Lg Lelectronics Inc.

Luca Gotti

Pietro Zenoni

Giovanni Pedrini

Rosario Castelli

Giorgio Bertocchi

Mauro Varischetti

Andrea Gotti

Ruggero Magoni

Mirko Ruggeri

A textile machine receives a plurality of yarns from respective feeders, each provided with a control unit that calculates, for each garment produced, the amount of yarn consumed (YCmeas) and compares it with a reference consumption value (YCref). If the difference exceeds a preset limit value (% max) that indicates an anomaly, then an alarm is generated. Periodically, the control unit calculates an average consumption value (YCmed) on the basis of a preset number (Nmed) of already-finished garments, and compares it with the reference consumption value (YCref). If the difference exceeds a preset threshold value (% maxmed), then the reference consumption value (Yref) is set to the average consumption value (Ymed).

Method for controlling the consumption of yarn in a weaving process

A yarn feeder is provided with a drum which is driven to rotate by a motor controlled by a control unit for drawing yarn from a reel and winding it upon itself in the shape of loops forming a stock. The control unit estimates the stock on the drum on the basis of an information indicative of the amount of yarn which is unwound from the drum upon request from a downstream machine, and of an information indicative of the amount of yarn which is wound on the drum, and retroactively controls the motor to substantially stabilize the stock on a reference value. The control unit also performs a parallel correction routine in which compares the stock with the reference value to estimate a stock status RES&#x3c;REF_RES or RES&#x2267;REF_RES, wherein RES is the estimated stock and REF_RES is the reference value.

Stock-controlling method for a storage yarn feeder with rotary drum

The yarn tension is modulated by a yarn-braking device controlled by a control unit which receives signals of measured tension from a tension sensor and compares them with a reference tension signal in a control loop; as long as the reference tension remains unchanged, a first set of coefficients is used in the control loop causing the control loop to have a relatively slow behavior in relation to the error-compensating action; when a change in the reference tension occurs, the system switches to a second set of coefficients causing the control loop to have a relatively fast behavior; the second set of coefficients is maintained as long as the difference between the second value of the reference tension and the measured tension remains greater or equal to a predetermined minimum value, then the system switches again to the first set of coefficients.

Tension-controlling method for a yarn unwinding from a storage yarn feeder to a textile machine

In order to detect the stop of the yarn unwinding from a yarn feeder provided with a stationary drum and with a sensor generating a pulse per each yarn loop unwound from the drum, a threshold time interval is continuously computed, which corresponds to the maximum interval between two successive pulses, above which it should be regarded that an accidental stop of the yarn has occurred. The threshold time interval is updated in real time as a function of the yarn-drawing speed. Then the delay from the last pulse is continuously measured and compared with the updated threshold time interval. The machine is stopped when the measured delay overcomes the updated threshold interval.

Method for detecting the stop of the yarn unwinding from a yarn feeder provided with a stationary drum

A knitting line comprises a plurality of yarn feeders from which a downstream machine draws respective yarns. The machine is provided with selection elements adapted to vary the state of selection of the yarn feeders in relation to the angular position of the machine. Each of the yarn feeders is provided with a stationary drum and with a yarn count sensor arranged to generate a pulse per each yarn loop unwound from the drum. A selection signal is periodically sent to the yarn feeders, which is indicative of the state of selection of the individual feeders in relation to the angular position of the machine. For each of the selected feeders, a threshold time interval is continuously calculated, which corresponds to the maximum interval between two successive pulses, above which it should be regarded that an accidental stop of the yarn has occurred, and is updated in real time as a function of the yarn-drawing speed, the delay from the last pulse is continuously measured and compared with the updated threshold time interval, and the downstream machine is stopped when the measured delay exceeds the updated threshold interval.

Method and apparatus for detecting accidental stops of the yarn on a knitting line

The tension is modulated by a weft-braking device controlled by a tension control block programmed for comparing the measured tension with a reference tension, and for transmitting a braking level signal to the weft-braking device, which braking level signal is adapted to minimize the difference between the measured tension and the reference tension. The yarn consumption speed is calculated, then the yarn consumption speed is compared with a predetermined threshold speed, and if the calculated consumption speed overcomes the predetermined threshold value, the tension control block is enabled, while, if the calculated consumption speed is lower than the threshold value, the tension control block is disabled and the last signal generated by the latter is maintained as braking signal, until the yarn consumption speed overcomes again the threshold value.

Method for controlling the tension of the yarn unwinding from a negative yarn-feeder for textile machines, and apparatus for carrying out such method

A yarn recovering device for textile machines, arranged upstream of a textile machine for temporarily recovering a length of yarn previously fed to the machine, and for returning it subsequently. A motorized reel has a substantially axial inlet port and an outlet port on its lateral surface, with a passage for the yarn between the ports. The reel is operatable to rotate from a resting configuration, in which it is kept still, to an active, yarn-recovering configuration, in which it is driven in one direction for winding the yarn on itself and recovering it from the machine, to a subsequent active, yarn-unwinding configuration, in which it is driven in the opposite direction for unwinding the yarn from itself and returning it to the machine. A position sensor measures the position of the reel and sends a corresponding measured position signal to a position control loop which compares the measured position signal with a reference position signal corresponding to a desired position for the motorized reel, and drives the reel in such a way as to minimize the difference between the measured position and the desired position.

Yarn-recovering device for textile machines

A control unit for yarn-braking devices in weft feeders for looms, in which the yarn unwinding from the feeder is pressed between a drum and a braking member connected to two linear actuators controlled by position and provided with position sensors. A position control loop receives a position signal from the sensor and compares it with a reference variable in a subtracter for obtaining a position error. A position compensator receives the position error and outputs a reference current entering a current control loop connected to generate a voltage that supplies the actuator. The compensator incorporates a control transfer function that is variable as a function of an elastic constant of a mass-spring equivalent system, where the mass is the mass of the parts in motion between the braking member and the actuators, and the elastic constant matches with the elastic constant of the elastic elements.

Control unit for yarn-braking devices in weft feeders for looms, and tuning method therefor

The three-way connector comprises a first, a second and a third gates directly connected to one another. The first and second gate are pluggable onto respective spans of a bus, and the third gate is connectable to a weft feeder. The three-way connector further comprises a permanent memory containing an identifying code for the associated weft feeder. A managing unit drives a serial bus to which a plurality of weft feeders are connected. The serial bus comprises the cable spans, serially connected to one another through the first and second gates of the connectors, the weft feeders being connected to respective third gates of the connectors.

Three-way connector for connecting weft feeders of textile machines to a serial bus, and a control system based thereon

The method consists in determining the angular positions of the rotor, which are useful for switching the phase currents, by deducing them from the sampled reading of the phase voltages, and in measuring the current of each phase by deriving it from the detection of the voltage that is present across a shunt resistor inserted on the negative power supply conductor of the three-phase star bridge of the driving inverter that generates the set of three phase voltages supplied to the motor.

Method and device for controlling electric motors of the brushless direct-current type, particularly for moving the weft winding arm in weft feeders for weaving looms

A method for controlling electrically actuated weft brakes for automatically adjusting mechanical tension of a weft thread in textile machines with mechanical insertion, comprising the steps of: generating and modulating an excitation current of an actuator of an electrically actuated brake. The above step is performed with a device which comprises a control chip which is sensitive both to variations of mechanical tension measured on the left thread and to an actual value (v) of a travel speed of the weft thread during insertion; the control loop is adapted to recondition a reference parameter of the braking action, determined by the control loop on the basis of a reference tension and a measured tension, with a multiplication factor which is represented by a decreasing function &lsqb;f(v)&rsqb; of the actual value (v) of the travel speed of the weft thread.

Weft tension brake control

A device for moving and controlling a weft winding arm in weft feeders for weaving looms, comprising a switched-reluctance motor which is controlled by a first closed loop for speed control, having its own reference variable and its own measured variable, and by a second closed loop for controlling the current that circulates in the phase of the motor, also having its own reference variable and its own measured variable; the reference variable of the first loop corresponds to the rotation rate that the winding arm must assume in order to correctly restore the turns of the weft reserve, and the reference variable of the second loop is constituted by a current value computed by the first control loop.

Device and method for moving and controlling weft winding arm in weft feeders

A weft feeder comprising weft sensors with movable magnetic elements that cooperate with respective detectors located outside the feeder drum; the detectors react with a signal, without contact, when the position of the corresponding weft sensor changes. Each detector in turn comprises an acquisition sensor capable of providing an analog signal, in terms of voltage, that can vary in a linear manner as the angular positions of the movable magnetic elements of the weft sensors vary. The acquisition sensors are operatively connected to a microprocessor for controlling the motor of the feeder, which is programmed to automatically set the values of the weft presence threshold and of the weft absence threshold and to filter the values of said signals.

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Albino, Italy

Luca Gotti