Pneumatic stretching device of the weft thread for air-jet weaving looms, with a weft deflecting head arranged inside the launch channel of the reed

摘要

Pneumatic weft thread stretching device (1) for air-jet weaving looms comprising an oscillating sley (S) and a reed (R) integral therewith consisting of several adjacent teeth shaped so as to form a weft launch channel (C). A stretching device (1), slidingly mounted on the sley (S) so that it can be fastened in a position at will on said oscillating sley (S), comprises a thinner weft deflecting portion (3i) arranged inside said reed launch channel (C) adjacent to the bottom wall of the same and a thicker portion (3e) facing the reed, said portions (3i, 3e) being partly separated by a cavity (9) wherein picking up of the weft thread takes place. The weft deflecting portion (3i) comprises fixed deviation means to displace the tip of said weft thread (W) from the bottom area of the launch channel (C) towards a nozzle (7) in said picking up cavity (9), said nozzle (7) being fed by a pipe (6) at least partly housed in said thinner portion (3i) and being apt to deliver a compressed air jet into said cavity (9). The thicker portion (3e) facing the reed (R) comprises a catching tube (8) facing said nozzle (7) on the opposite side of said cavity (9) for catching the weft thread (W) from said picking up cavity (9) under the action of said compressed air jet.