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

摘要

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.

主权项

1. A weft-braking device for installation on a yarn feeder provided with a stationary drum having a plurality of yarn loops wound thereon which are to be unwound upon request from a downstream machine, comprising:
a first annular plate coaxially supported in front of a delivery end of the drum, and a second annular plate which is coaxially biased against said first annular plate by driving means, said yarn being adapted to run between said annular plates to receive a braking action by friction from them, wherein said driving means comprise at least one piezoelectric actuator which is a flat, piezoelectric bending actuator deformable by bending in response to a voltage applied thereto and has a movable operative end which is operatively connected to said second annular plate and a stationary operative end which is anchored to a stationary support, wherein said piezoelectric actuator has an annular profile and is a multilayer, monolithical-type actuator formed by a plurality of layers made of a piezoelectric material alternated to layers of a conductive material, said layers being bonded to one another by sintering.