Weft feeder with rethreading and braking devices

A weft feeder for gripper or projectile looms allows an operator promptly to restore the continuity of a weft yarn from a yarn feed spool to members for weft insertion into a loom shed, in case of weft yarn breakage or interruption. Downstream of a first yarn guide outlet, there are mounted a double-leaf brake, a separating element, and a second downstream yarn guide eyelet. The separating element is controlled by an actuator so as to separate two brake leaves of the double-leaf brake and to form a duct to guide the weft yarn from the first eyelet to the second eyelet.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention concerns improvements in weft feeders for gripper or 
projectile looms, allowing an operator promptly to restore the continuity 
of the weft yarn from the yarn feed spool or reel to the members for weft 
insertion into the loom shed, in case of yarn breakage or interruption. 
2. Description of the Related Art 
In most cases, in the event of yarn breakage, it is necessary to introduce 
a new weft yarn into the weft feeder, that is, to perform a series of 
operations by which the free weft yarn end, fed from the spool or reel, is 
guided into the various passages provided therefor in the weft feeder, so 
as to be then readily introduced into the loom weft insertion members. 
FIG. 1 of the accompanying drawings shows the prior art weft feeder 
configuration to which reference is made in the description given 
hereinafter of the invention. The weft yarn 1, drawn from the spool 2, is 
guided through an eyelet 3 into the inner cavity of the winding arm 5 
which, moved by an electric motor 4, winds it up into even turns around 
the winding unit or drum 6. The weft yarn 1 is then unwound from said drum 
6 in an axial direction--drawn by the loom weft insertion members--and it 
is braked by known type brake means, consisting of a ring 7 carrying an 
annular brush 8, whose bristles press--with an adjustable 
pressure--against the round-shaped periphery of the drum 6. The weft yarn 
1 is finally let out through a guide eyelet 10, centered on the drum axis 
and carried by a radial bracket 9 positioned alongside the drum 6. 
Downstream of the yarn guide eyelet 10, use is often made--to improve and 
complete the action of the annular brush brake 8--of a double-leaf brake 
21, and/or of a weft tension device 31, comprising an oscillating lever, 
useful especially in gripper looms; both these devices--known per se--are 
carried by the same bracket 9 and are positioned in alignment with the 
eyelet 10 on the drum axis. 
According to conventional technique, the previously described operation of 
introducing a new weft yarn into the weft feeder is carried out 
manually--with the help of a flexible threading hook which, as known, 
consists of a strip of flexible material ending with a slot or hook--and 
it is a rather long and toilsome operation which also requires a certain 
experience. Several expedients have so far been adopted to facilitate the 
insertion of a new weft yarn by means of a threading hook, for instance 
forming guides of various types allowing a quicker and safer introduction 
of the threading hook, as described for example in DE-2932782 and in 
EP-285592: according to this latter, the threading hook is used to insert 
the weft yarn also in the double-leaf brake and in weft tension device. 
In the attempt to make the above operation more automatic, it has more 
recently been proposed to introduce a new weft yarn into the weft feeder 
by means of compressed air jets, as described for example in DE-G-8712946, 
wherein successive yarn launching and guiding devices are provided to 
insert the yarn into the various passages, without the help of a threading 
hook. The most critical and difficult part is however the pneumatic 
introduction of the yarn into the guide eyelet 10, at the outlet of the 
weft feeder, in that very sharp deviations have to be imparted on the yarn 
in order to guide it from the drum periphery into said eyelet 10. 
According to EP-A1-436900, filed by the Applicant the introduction of the 
yarn into the guide eyelet 10 is efficiently obtained by positioning said 
eyelet along the rectilinear trajectory of the yarn coming out from a duct 
provided downstream of the winding arm, and by simultaneously removing the 
annular brush brake from its working position, so that the yarn, passing 
through the ring 7 of said brake, is then introduced into the eyelet 10. 
This system fully solves the above problem, but it supplies a solution 
which forms part of a totally automatic system to restore the continuity 
of the weft yarn from the spool to the loom; furthermore, it does not 
consider introducing the yarn into any additional devices--such as the 
double-leaf brake and the weft tension device--which, as already said, may 
often be provided (especially in gripper looms) downstream of the yarn 
guide eyelet 10, at the outlet of the weft feeder. 
OBJECT AND SUMMARY OF THE INVENTION 
The object of the present invention is to provide a solution which can be 
applied to partially automatic systems and which allows an operator, at 
the same time, to introduce the weft yarn into said additional devices at 
the outlet of the weft feeder. According to the invention, this object is 
reached with a weft feeder for gripper or projectile looms comprising: a 
body housing a motor; a drum mounted on the motor shaft and held 
stationary, around which a winding arm rotated by the motor winds up a 
weft yarn reserve; an extension of body carrying sensors to detect and 
control the yarn reserve being wound on the drum, as well as brake means, 
in the form of a ring with an annular brush, apt to brake the weft yarn 
against the end surface of the drum; pneumatic means to restore the 
continuity of the weft yarn from the feed spool to the loom, in case of 
yarn breakage or interruption, comprising at least one compressed air 
nozzle device positioned at the inlet of the weft feeder so as to 
introduce therein a new yarn fed from a spool or reel; and yarn launching 
and guiding means to introduce the yarn into a yarn guide eyelet, centered 
on the drum axis, at the outlet of the weft feeder. In said weft feeder: 
said outlet yarn guide eyelet is mounted on a movable support, so as to be 
shifted from the drum axis and be caused to intersect the yarn 
trajectory--determined by said compressed air nozzle device--at the outlet 
from the inner cavity of the winding arm, said winding arm being stopped 
in a preset angular position and the ring of the annular brush brake being 
provided with an outwardly flared radial notching in the same angular 
position; 
downstream of said outlet yarn guide eyelets there is mounted a double-leaf 
brake comprising an end eyelet, as well as an element apt to open the two 
leaves apart, under the control of an actuator, so as to form a duct for 
the yarn between said two leaves; 
downstream of said outlet yarn guide eyelet, there is mounted a weft 
tension device comprising an oscillating lever, positioned between said 
outlet yarn guide eyelet and an end yarn guide eyelet, and moving between 
a working position and a neutral position of weft insertion; 
downstream of said outlet yarn guide eyelet, there are mounted, in 
succession, both a double-leaf brake comprising an element opening the two 
leaves apart, and a weft tension device comprising an oscillating lever, 
an intermediate yarn guide eyelet being provided between said brake and 
said tension device and this latter device being in turn followed by an 
end yarn guide eyelet, said oscillating lever being controlled by said 
opening element of the double-leaf brake, which is in turn controlled by a 
pneumatic or electromechanical actuator. 
A compressed air device, consisting of a yarn suction nozzle, can moreover 
be mounted just after said outlet yarn guide eyelet. 
When the outlet yarn guide eyelet is mounted on a movable support, so as to 
be shifted from the drum axis and be caused to intersect the yarn 
trajectory at the outlet from the inner cavity of the winding arm, and--at 
the same time--said movable support carries, downstream of said outlet 
yarn guide eyelet, a double-leaf brake comprising an element opening the 
two leaves apart, an intermediate yarn guide eyelet, a weft tension device 
comprising an oscillating lever, and an end yarn guide eyelet, it can also 
be provided for the aforementioned actuators to be replaced by mechanical 
means, for instance simple fixed stops, which--following the movement of 
said support causing the outlet yarn guide eyelet to intersect the yarn 
trajectory--are apt to control said opening element of the double-leaf 
brake, as well as said oscillating lever of the weft tension device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference first of all to FIGS. 2 and 3 of the drawings, it can be 
seen that a low-pressure nozzle 11, fed with air from a pipe 12 by means 
of an on-off valve 13, is applied upstream of the weft feeder according to 
the invention: the weft yarn 1, introduced through the conical inlet 3, is 
thus launched by an air jet into the inner cavity of the winding arm 5 
which has been previously stopped in a fixed angular position, preset for 
example by means of an electromagnetic proximity switch 14. The movable 
support, consisting of a radial bracket 9 carrying the outlet yarn guide 
eyelet 10, is mounted on a pin 15 rotatable into an extension of the weft 
feeder body housing the motor 4, parallel to the axis of the drum 6, and 
can thus be shifted, by rotation, from a working position A to a position 
B (FIG. 3) in which the eyelet 10 intersects the trajectory of the weft 
yarn at its outlet from the inner cavity of the winding arm 5. To 
facilitate introducing the yarn into the eyelet 10, a lead-in mouthpiece 
in the form of a trumpet 19 can be provided in front of said eyelet 10, 
while a second compressed air nozzle 16 can be positioned downstream 
thereof: this latter nozzle 16, fed from a pipe 17 by means of an on-off 
valve 18, is apt to suck the weft yarn end into the trumpet 19. 
With the eyelet 10 in position B, the weft yarn 1--in order to be 
introduced therein--travels externally to the ring 7 of the annular brush 
brake 8, as shown in FIG. 2. Thus, to make sure that the weft yarn winds 
around the drum surface when the bracket 9 is counter-rotated to move the 
eyelet 10 back into the working position A, a radial notching 24 (FIG. 3), 
suitably flared outwardly, is provided on the ring 7 so as to let the yarn 
through and allow its insertion under the brush brake 8, thanks to the 
actual rotation of the bracket 9 moving back to position A. 
In the most simplified embodiment of the invention, the bracket 9 is 
manually rotated through a knob, but said rotation could obviously be 
controlled by a suitable pneumatic or electromechanical actuator. 
When the braking action of the annular brush brake 8 is not sufficient, 
said action is completed by a supplementary double-leaf brake 21, normally 
carried by said bracket 9 and positioned just downstream of the eyelet 10, 
as shown in FIG. 4. Said brake 21 consists of two elastic steel plates or 
leaves 23, carried by two pins 22 rotating about their own axes in 
opposite directions, so as to allow adjusting--by means of a knob 26--the 
mutual contact pressure between said two leaves 23. All these elements are 
mounted onto a support 25 comprising, at its outlet, a second yarn guide 
eyelet 20. 
Once the weft yarn 1 has been inserted into the eyelet 10, as shown in FIG. 
4, it can be very easily introduced by hand between the leaves 23 and also 
into the eyelet 20, if this latter eyelet is of the open type, namely of 
the type comprising a labyrinth-shaped radial notching 27, allowing the 
prompt insertion of the yarn while safely guiding it along its whole 
contour. With the arrangement of FIG. 4, since the notching 27 is 
positioned on the plane of the yarn trajectory and of the contact line 
between the two leaves 23, the introduction of the yarn into the eyelet 20 
is simultaneous to its insertion between said leaves. 
An improved solution according to the invention is shown in FIGS. 5 and 6, 
wherein the weft yarn 1 is pneumatically inserted into the double-leaf 
brake. Said solution consists in forming a duct for the yarn to be guided 
from the eyelet 10 to the eyelet 20, normally being in this case of the 
closed type. This duct is obtained by means of the compressed air suction 
nozzle 16, positioned just downstream of the eyelet 10--as already 
described heretofore--and by making use of a separating element 28 apt to 
part the two leaves 23, said separating element 28 having a wedge-shaped 
profile, best seen in FIG. 6, apt to penetrate between said two leaves 23 
and open them apart parallely to the weft feeder axis. The separating 
element 28 is moved by an actuator 29--which can be of the pneumatic or 
electromechanical type--between a rest position B (dash-and-dot lines in 
FIG. 5), and a working position A in which the leaves 23 are apart: when 
in this position, the separating element 28 allows itself to form a closed 
guiding duct--of more or less triangular shape--the walls of which consist 
of said two leaves 23 and of the actual separating element 28, as shown by 
wedge 32 in FIG. 6. This duct allows the operator to obtain--with the same 
air jet--the simultaneous insertion of the weft yarn between the leaves 23 
and through the eyelet 20 positioned downstream of the double-leaf brake 
21. 
FIGS. 7 and 8 show a different embodiment of the weft feeder according to 
the invention, wherein the double-leaf brake is replaced by a weft tension 
device 31. This device 31 consists of a body 33, fixed to the same bracket 
9 carrying the outlet yarn guide eyelet 10 followed by the compressed air 
suction nozzle 16. A third yarn guide eyelet 30 is mounted on the end part 
34 of the body 33; between the two eyelets 10 and 30, there is interposed 
a lever 35, oscillating about a pin 36--parallel to the weft feeder 
axis--between two positions A and B (FIG. 8). In position B, the lever 35 
is in working conditions, balanced between the force imparted by weft 
tension and that of a preloaded spring 37 acting thereon, which can be 
adjusted by means of a knob 38. 
To insert the yarn 1 into the weft tension device 31 by means of a 
compressed air jet, it is necessary to shift back the lever 35 into 
position A (shown in dash-and-dot lines in FIG. 8); this shifting can be 
done by means of an actuator 39--of the pneumatic or electromechanical 
type--a movable pin 40 of which presses against an upper square appendix 
41 of the lever 35, so as to rotate the lever 35 clockwise (FIG. 8) moving 
it to the left of the yarn trajectory. 
The most complete and improved embodiment of the weft feeder according to 
the invention--especially suited for gripper looms--is shown in FIG. 9. 
This embodiment combines, in succession, the two aforedescribed 
devices--namely the double-leaf brake 21 and the weft tension device 31 
--which, in the other embodiments, are mounted separately. In this case, 
the forming of the duct between the two leaves 23--according to the 
principles set forth hereabove--allows the operator to guide the weft yarn 
1 through the two successive eyelets 20 and 30, thanks to the air jet 
blown by the nozzle 16. A single rod 42, moved by an actuator 43, causes 
both the parting of the leaves 23--consequently forming said guiding 
duct--and the proper shifting of the lever 35 of the weft tension device 
31. 
According to another embodiment of the invention, it can also be 
provided--when the yarn is introduced through the outlet yarn guide eyelet 
10 owing to rotation of the bracket 9, as previously described with 
reference to FIG. 3--for said rotation to simultaneously cause the 
shifting of the double-leaf brake 21 and of the weft tension device 31 
from the working position A to the position B of yarn introduction shown 
in FIG. 3. In this case, simple fixed stops can be arranged in the yarn 
launching position B, to mechanically part the leaves 23 and shift the 
lever 35 following said rotation of the bracket 9, with no need to provide 
for any actuators.