Weft-braking device for yarn feeders provided with a stationary drum

摘要

The weft-braking device comprises a first annular plate (36) coaxially supported in front of the delivery end of a stationary drum (12) of a yarn feeder (10), and a second annular plate (44) which is coaxially biased against the first annular plate (36) by driving means (46). The yarn (Y) is adapted to run between the annular plates (36, 44) in order to receive a braking action by fricton. The driving means comprise at least one piezoelectric actuator (76), which is deformable in response to a voltage applied thereto and has a movable operative end (76a) which is operatively connected to the second annular plate (44) and a stationary operative end (76b) which is anchored to a stationary support (52).