Patent application number | Description | Published |
20100162773 | Positive yarn feeder with tension limiter - 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. | 07-01-2010 |
20110000306 | Method for detecting the stop of the yarn unwinding from a yarn feeder provided with a stationary drum - 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. | 01-06-2011 |
20120031148 | Method and apparatus for detecting accidental stops of the yarn on a knitting line - 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. | 02-09-2012 |
20130068872 | Positive yarn feeder with tension limiter - 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. | 03-21-2013 |
20130167968 | WEFT-BRAKING DEVICE FOR YARN FEEDERS PROVIDED WITH A STATIONARY DRUM - 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. | 07-04-2013 |
20130168480 | YARN FEEDER PROVIDED WITH A STATIONARY DRUM AND WITH A CONTROLLED, WEFT-BRAKING DEVICE - 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. | 07-04-2013 |
20130327877 | Tension-controlling method for a yarn unwinding from a storage yarn feeder to a textile machine - 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. | 12-12-2013 |
20140191074 | Yarn-feeding assembly for textile machines - 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. | 07-10-2014 |