Abstract: A yarn-winding assembly mounted on a support is provided with a motorized spool and with an oblique spacing pin, between which a yarn is wound. The spacing pin is supported so that it can rotate about an axis of the motorized spool by unidirectional rotary support elements. The spacing pin rotates freely with respect to the spool when the latter rotates in the yarn unwinding direction and the former is retained from rotating by stop elements, and is instead integral with the spool when the spool rotates in the opposite yarn rewinding direction.

Abstract: 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).

Abstract: 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.

Abstract: 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.

Abstract: 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<REF_RES or RES?REF_RES, wherein RES is the estimated stock and REF_RES is the reference value.

Abstract: 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.

Abstract: 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.

Abstract: 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.

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.

Abstract: 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 behaviour 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 behaviour; 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.

Abstract: 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.

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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.