(57) In a measuring weft feeder for fluid jet looms - equipped with an electromagnetic
yarn stopping device (8) comprising at least one electromagnetic coil (12) and a movable
core (13) of ferromagnetic material subject to the contrasting actions of said coil
(12) and of a return spring (14), so as to move a rod (9), engaging and stopping the
yarn at the outlet of the weft feeder, between a withdrawn rest position and a projecting
yarn stopping position in which the end of the rod (9) is positioned into a cavity
(10) formed for the purpose on the drum periphery (3), close to its free end - the
movable core (13) of the yarn stopping device is formed of a substantially cylindrical
hollow head (15) of ferromagnetic material and of a cylindrical rod (9) of ceramic
material axially positioned into the hollow of the head (15), and the outer surface
of the rod (9) and the inner surface of the hollow head (15) are provided with grooves
(17,17A,18,18A) along their directrices, while the remaining hollow part between the
head and the rod is filled with plastic material (16) which is pressure injected to
block the rod (9) into the head (15). According to the invention, the walls of the
drum cavity (10) housing the end of the rod (9) of the yarn stopping device - which
are positioned according to the generating lines of the drum - are inclined so as
to open outwardly wide apart.
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