Negative yarn feeder with weft-braking device

Abstract

Yarn loops are unwound from a stationary weft-winding drum during a weft insertion. A weft-braking device locks the yarn unwinding from the drum at the end of the insertion, and comprises at least one braking member which is arranged by side of the drum near its delivery end and is movable under control of an actuator between a resting position in which it is spaced from the outer surface of the drum and does not interfere with the unwinding yarn, and an operative position in which it engages the outer surface of the drum and cooperates with it to brake the yarn.

1 . A negative yarn feeder, comprising a stationary weft-winding drum from which yarn loops are unwound during a weft insertion, and a weft-braking device for locking the yarn unwinding from the drum at the end of said insertion, wherein said weft-braking device comprises at least one braking member which is arranged by side of the drum near its delivery end and is movable under control of actuator means between a resting position, in which it is spaced from the outer surface of the drum and does not interfere with the unwinding yarn, and an operative position, in which it engages the outer surface of the drum and cooperates with it to brake the yarn. 
     
     
         2 . The negative yarn feeder of  claim 1 , wherein said actuator means consist of a linear actuator provided with an operating rod, to which said braking member is anchored, which is movable in a radial direction with respect to the drum between said resting position and said operative position. 
     
     
         3 . The negative yarn feeder of  claim 1 , wherein said at least one braking member is mounted to a support integral with the feeder and, in said resting position, is received in a respective seat of said support. 
     
     
         4 . The negative yarn feeder of  claim 3 , wherein said support is shaped as a ring surrounding the drum and supports at least two of said braking members spaced at equal angles. 
     
     
         5 . The negative yarn feeder of  claim 1 , wherein said braking member is a bristle brush. 
     
     
         6 . The negative yarn feeder of  claim 5 , wherein said bristle brush is shaped as an angular sector. 
     
     
         7 . The negative yarn feeder of  claim 1 , also comprising a substantially frustoconical anti-balloon funnel, which is coaxially arranged in front of the drum with its larger base facing the delivery end of the drum, and in that the innermost edge of the larger base of the funnel is smaller in diameter than the winding diameter of the drum. 
     
     
         8 . The negative yarn feeder of  claim 7 , wherein said anti-balloon funnel is supported at an axially adjustable position in relation to the drum. 
     
     
         9 . The negative yarn feeder of  claim 7 , wherein said anti-balloon funnel consists of a plurality of equally-spaced rods arranged along the generatrices of a trunk of cone and having one end attached to a smaller ring defining the smaller base of the trunk of cone, and the opposite end attached to the larger ring defining said larger base of the frustum of cone. 
     
     
         10 . A weft-braking device installable on a negative yarn feeder provided with a weft-winding drum for locking the yarn unwinding from the drum at the end of an insertion, comprising at least one braking member connectable to the feeder by side of the drum and movable under control of actuator means between a resting position in which it is spaced from the drum and does not interfere with the unwinding yarn, and an operative position in which it engages the outer surface of the drum near its delivery end and cooperates with it to brake the unwinding yarn.