Lg Lelectronics Inc.

L.g.l. Elettronica S.p.a.

Pietro Zenoni

Giovanni Pedrini

Rosario Castelli

Luca Gotti

Giorgio Bertocchi

Mauro Varischetti

Ruggero Magoni

Agostino Facotti

Mirko Ruggeri

Enrico Zenoni

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 winding assembly installed on a support includes a motorized spool and an oblique spacer pin, between which a yarn is wound. The spacer pin is supported rotatably by a rotating supporting component so that it is entrained in two directions by the yarn wound between the spool and the spacer pin. The rotation of the spacer pin is delimited by an element of arrest at least in a direction of unwinding the yarn.

Yarn feeder with motorized yarn winding spool

A motorized rotary drum supported on a motor housing bears a plurality of yarn loops wound thereon, such loops being adapted to be unwound upon request from a downstream machine. A yarn-unwinding sensor comprises light-emitting elements and light-receiving elements both of which are integral with the motor housing. Light-guiding elements which are integral with the drum guide the light from the light-emitting elements to a window which is defined on the rotary drum in a position such that it is repeatedly engaged by the yarn during its rotary unwinding motion, and vice versa. A reflecting surface reflects the light coming out of the window back towards the window. Light-deviating elements which are integral with the motor housing deviate the light coming back from the window towards the light-receiving elements. The unwinding of a yarn loop from the drum is determined on the basis of the variation of light resulting from the yarn transiting on the window.

Yarn feeder with rotary storage drum and yarn-unwinding sensor

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

A drum has a plurality of yarn loops wound thereon which are to be unwound upon request from a downstream machine. A weft-braking device provided with a braking member having a circular profile is biased against a delivery edge of the drum by driving elements. The yarn is adapted to run between the delivery edge and the braking member to receive a braking action by friction from them. The driving elements comprise at least one piezoelectric actuator which is deformable in response to a voltage applied thereto and has a movable operative end which is operatively connected to the braking member and a stationary operative end which is anchored to a stationary support.

Yarn feeder provided with a stationary drum and with a controlled, weft-braking device

The weft-braking device comprises a first annular plate coaxially supported in front of the delivery end of a stationary drum of a yarn feeder, and a second annular plate which is coaxially biased against the first annular plate by driving elements. The yarn is adapted to run between the annular plates in order to receive a braking action by friction. The driving elements comprise at least one piezoelectric actuator, which is deformable in response to a voltage applied thereto and has a movable operative end which is operatively connected to the second annular plate and a stationary operative end which is anchored to a stationary support.

Weft-braking device for yarn feeders provided with a stationary 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

A motorized yarn-winding drum holds a plurality of loops of yarn wound thereon and is driven to rotate for drawing said yarn from a reel and feeding it to a general downstream machine. A movable guiding member is biased to slideably engage the yarn unwinding from the drum and to deviate its path, by a spring acting in contrast to the tension of the yarn, thereby generating a reserve releasable in response to tension peaks on the yarn. The stroke of the guiding member is limited by a stop defining a position of maximum deviation of the yarn. The spring has one end operatively connected to the guiding member and one opposite end connected to driving elements operable for applying a load to the spring, with the guiding member abutting against said stop. The driving elements are controlled by a control unit which is programmed to adjust the load as a function of a desired feeding tension.

Positive yarn feeder with tension limiter

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

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 self-adjusting braking device for weft feeders, comprising a frustum-shaped braking body that acts on a thread, is suspended elastically in front of the drum of the feeder and is pushed into elastic tangent contact with the drum along an exit circumference of the drum. The braking body has, at a larger-diameter region thereof designed to make contact with the drum, a discontinuous annular contact element, with a plurality of through slits which are arranged so as to be equidistant and delimit a row of contact laminas.

Self-adjusting braking device for weft feeders

An anti-balloon device, to be placed downstream of a weft feeder for weaving looms, comprising a structure which forms a substantially tubular through cavity, preferably substantially frustum-shaped; the cavity is crossed by an unwinding thread that arrives from the weft feeder and controls the passage of the thread, by opposing the centrifugal force that affects it. The structure is shaped like a bottomless basket which is formed by rods lying longitudinally between end elements which connect the rods; the end elements are end rings which are mutually angularly spaced so as to surround the cavity in order to control the passage of the thread.

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Leffe, Italy

Pietro Zenoni