Weft thread gripping mechanism for a loom with a travelling-wave shed and a disk-type beat-up motion

The proposed weft-thread gripping mechanism includes gripping members elastically tightened together and installed at the side of exit of weft thread carriers from a travelling-wave shed. The gripping members, one of which is movable relative to the other one, are mounted on a shaft of a disk-type beat-up motion so as to be rotatable therewith and displaceable, after gripping the weft thread, lengthwise the shaft axis in the direction from the travelling-wave shed. Located on the shaft of the disk-type beat-up motion is a stationary stop cooperating with the movable gripping member at the moment of the closest approach of the gripping members to the travelling-wave shed for a gap to be formed therebetween a weft thread passes through. This makes it possible to keep taut the weft thread advanced to the fell of the cloth till the end of the process of the cloth formation.

FIELD OF THE INVENTION 
The present invention relates to looms with a travelling-wave shed and, 
more particularly, to weft thread gripping mechanisms for looms with a 
travelling-wave shed and a disk-type beat-up motion, wherein the disks are 
secured on the shaft. 
BACKGROUND OF THE INVENTION 
In the loom with the travelling-wave shed and the disk-type beat-up motion, 
the weft thread is propulsed by the carriers and advanced to the fell of 
the cloth along a line inclined towards the fell. As a result, by the 
moment the carrier emerges from the shed, in the extreme zone thereof 
there appears the excess amount of the weft thread which is determined as 
the difference between the length of the helical groove formed by the 
depressions in the disks and the width of the extreme zone. Therefore, for 
the normal process of the cloth formation a mechanism is required which 
will remove this excess amount of the weft thread from the extreme zone. 
Besides, the weaving practice has proven that the process of formation of 
the cloth edge is more stable (does not noticeably differ from the process 
of formation of the cloth body), if the end of the weft thread is kept 
taut till the end of the cloth formation process, across the entire 
weaving width. 
When used for this purpose are the known grips stationary mounted at the 
exit of the carriers from the travelling-wave shed only gripping and 
holding of the weft thread are ensured, whereas, due to structural 
features of these grips, the removal of the excess amount of the weft 
thread under a definite tension required for producing a high-quality 
cloth is unattainable. 
At present, there is known an apparatus for gripping the weft thread 
disposed next to the butt surface of the shaft of the disk-type beat-up 
motion at the exit of the weft thread carriers from the looming-up zone, 
i.e. from the traveling-wave shed and intended for gripping the weft 
thread behind the carrier, conveying it towards the fell of the cloth and 
keeping it taut by way of compensating for an excess length of the weft 
thread till the latter is interlaced with the warp threads of the cloth. 
This apparatus includes gripping members one of which is installed 
displaceably relative to the other one for the weft thread to be thereby 
gripped. The gripping member installed stationary is made as a plate 
secured on the loom frame, whereas the movable gripping member is made as 
a bush with an engaging tooth rotating in the same direction with the 
disk-type beat-up motion. 
The rotatable bush and the stationary plate are tightened together by a 
spring. In the process of gripping of the weft thread, the tooth brings 
the end of the weft thread to the stationary plate and, due to the mutual 
friction, the gripping occurs. With the engaging tooth going on displacing 
relative to the stationary plate, due to different coefficients of 
friction of the stationary plate and the tooth, the weft thread is placed 
under tension, i.e. the excess amount of the weft thread is withdrawn from 
the shed. The thread is kept taut as long as the engaging tooth interacts 
with the profile of the stationary plate. 
However, since this apparatus depends for its operation on the friction 
between the thread, the stationary and the movable gripping members and 
also due to the lengthwise irregularity of the weft thread, the tensioning 
and holding thereof is unstable and deficient. 
Besides, the abilities of this device to apply tension to the end of the 
weft thread are limited. 
It is an object of the present invention to obviate the disadvantages. 
The principal object of the present invention is to provide a weft thread 
gripping mechanism for a loom with a travelling-wave shed and a disk-type 
beat-up motion which should make it possible, after the weft thread is 
gripped and while it is transferred to the fell of the cloth, to keep it 
taut till it gets interlaced with the warp threads. 
Another object of the present invention is to provide a weft thread 
gripping mechanism for a loom with a travelling-wave shed which should 
make it possible to improve the process of formation of the edge of the 
cloth. 
One more object of the present invention is to produce a high-quality 
cloth. 
BRIEF DESCRIPTION OF THE INVENTION 
This and other objects are attained by that in a weft thread gripping 
mechanism for a loom with a travelling-wave shed and a disk-type beat-up 
motion including gripping members elastically tightened together and 
installed at the side of exit of the weft thread carriers from the 
travelling-wave shed, with one of the gripping members installed so as to 
be displaceable relative to the other one to thereby form a gap 
therebetween for the weft thread to pass through, in accordance with the 
invention, the gripping members are mounted on a shaft of the disk-type 
beat-up motion so as to be rotatable therewith and be displaceable, after 
gripping the weft thread, lengthwise the axis of the shaft in the 
direction from the travelling-wave shed, a stationary stop being secured 
to the very same shaft for cooperating with the movable gripping members 
at the moment of the closest approach of the gripping members to the 
travelling-wave shed for said gap to be formed therebetween. 
Arrangement of the gripping members on the shaft of the disk-type beat-up 
motion allows to shift the gripped end of the weft thread in step with the 
movement thereof towards the fell of the cloth. In addition, due to the 
displacement of the gripping members lengthwise the shaft axis, it is 
possible to transfer the gripped end of the weft thread in the direction 
from the looming-up zone thus removing the excess amount of the weft 
thread from the extreme zone of cloth formation and bringing the gripping 
members to the looming up zone as close as possible for seizing the weft 
thread. 
According to the invention, the gripping members are mounted on the shaft 
of the disk-type beat-up motion with the aid of a doble-arm lever 
pivotable in the plane parallel to the axis of the shaft of the disk-type 
beat-up motion from a stationary cam installed on a frame of the loom 
coaxially with the shaft of the disk-type beat-up motion, one arm of the 
lever being provided with a roller constantly contacing the stationary 
cam, the other arm serving as a stationary gripping member in contact with 
the movable gripping member secured to the same arm of the lever through a 
spring-loaded rod displaceable from a stationary stop. 
It is preferable to mount the stationary stop and the axle of the 
double-arm lever on the shaft of the disk-type beat-up motion with the use 
of a bush rigidly secured on this shaft. This enables to secure all parts 
of the proposed weft thread gripping mechanism on the shaft of the 
disk-type beat-up motion in a simplest way without modifying the shaft 
itself, which, in turn, makes it possible to quickly and easily place this 
weft thread gripping mechanism in service on the already operating looms 
with the travelling-wave shed an the disk-type beat-up motion. 
According to an alternative embodiment of the invention, the double-arm 
lever is elastically urged against the stationary cam, while the roller of 
the double-arm lever contacts the stationary cam over the butt surface 
thereof, due to which the excess amount of the weft thread may be removed 
from the extreme zone of cloth formation in compliance with the preset law 
without the profile of the butt surface of the stationary cam being 
changed. 
It is preferable also to make the bush as a sleeve accommodating inside the 
stationary cam provided with a shaped slot to receive the roller of the 
double-arm lever, the axle of the roller passing through a hole made in 
the side surface of the bush. 
According to another embodiment of the invention, the contact of the 
stationary stop with the spring-loaded rod occurs through an intermediate 
rotatable member with the axle of rotation mounted on the double-arm lever 
which makes it possible to seize the weft thread reliably and quickly. 
According to still another embodiment of the invention, between the 
gripping members mounted on the shaft of the disk-type beat-up motion and 
the travelling-wave shed, along an imaginary line forming a continuation 
of the fell of the cloth, on the loom frame, arranged are an additional 
gripping pair of jaws for nipping the weft thread forced to the fell of 
the cloth and held by the gripping members, and a cutter for severing the 
weft thread held by the additional gripping pair of the jaws and the 
gripping members, the shaft of the disk-type beat-up motion being 
outfitted with a profiled cam contacting, via the roller, with a movable 
blade of the cutter and the movable jaw of the gripping pair for the 
displacement thereof. This enables to hold the end of the weft thread taut 
till the end of the cloth-forming process across the entire weaving width. 
The movable jaw of the gripping pair and the movable blade of the cutter 
are preferably placed on a common axle and elastically pressed against the 
profiled cam via a spring-loaded bell-crank lever mounted on the loom 
frame due to which the additional gripping pair and the cutter may be 
controlled by one and the same cam. 
Thus, the proposed weft thread gripping mechanism makes it possible to 
improve the process of the cloth formation and to enhance the quality of 
the produced cloth.

The proposed weft thread gripping mechanism is employed in the known looms 
with a travelling-wave shed A and a disk-type beat-up motion 1. Since the 
structure of the weft thread gripping mechanism is not governed by the 
structure of the loom, the structure of weft thread carriers 2 and the 
structure of apparatus 3 for propelling the carriers 2 in the 
travelling-wave shed A, they are neither dealt with in the description nor 
shown in the drawings because used as these apparatus may be any apparatus 
known in the art which serve this purpose when used in the loom. 
The disk-type beat-up motion 1 includes a drive shaft 4 whereon secured are 
disks 5 with teeth 6 (FIG. 2). The disks 5 (FIG. 1) are secured on the 
shaft 4 with a shift, whereby the crests of the teeth form helical 
surfaces B which engage a weft thread 7 unwound from a spool 8 of the 
carrier, advance it to a fell 9 of a cloth 10 and force it thereto (in 
FIG. 1 the helical surface B in plan is aligned with the weft thread 7). 
The weft thread gripping mechanism is installed at the side of exit of the 
weft thread carriers 2 from the travelling-wave shed A, i.e. from a 
looming-up or weaving zone C, and includes gripping members 11 and 12 
elastically tightened together, one of these members, for instance, the 
gripping member 11, being installed so as to be displaceable relative to 
the gripping member 12 for a gap accommodating the weft thread 7 to be 
thereby formed therebetween. Therefore, the gripping member 11 will be 
subsequently referred to as the movable gripping member 11. The gripping 
members 11 and 12 are mounted on the shaft 4 of the disk-type beat-up 
motion 1 so as to be rotatable therewith and displaceable lengthwise the 
axis of the shaft 4 in the direction from the travelling-wave shed A. 
Secured on the same shaft 4 is a stationary stop 13 adapted to cooperate 
with the movable gripping member 11 at the moment of the closest approach 
of the gripping members 11 and 12 to the travelling-wave shed A for a gap 
to be formed therebetween. 
For convenience in installation of the gripping members 11 and 12 on the 
shaft 4 rigidly secured to the latter by any known manner is a bush 14 
provided with a flat surface 15 (FIG. 3). On this bush 14, on the side of 
the flat surface 15 secured with the aid of an axle 16 is an L-shaped 
double-arm lever 17 (FIG. 1). On one arm 18 of the double-arm lever 17, 
through the medium of an axle 19, secured is a freely rotating roller 20, 
the second arm of this lever being provided with a flat portion and 
serving as the gripping member 12. 
The double-arm lever 17 is pivotable about the axle 16 and the pivoting 
occurs in the plane parallel to the axis of the shaft 4 above the flat 
surface 15 (FIG. 3) due to a stationary cam 21 (FIG. 4) installed on a 
frame 22 of the loom coaxially with the shaft 4 of the disk-type beat-up 
motion 1. The profiled surface of the stationary cam 21 is in constant 
contact with the roller 20 of the double-arm lever 17. For this, the 
double-arm lever 17 is elastically urged against the stationary cam 21 by 
a spring 23 one end of which is attached to the butt of the bush 14 (FIG. 
3) and the other, to the axle 19 of the roller 20, as is shown in FIG. 3. 
The second arm of the double-arm lever 17 (FIGS. 1 and 4) mounts the 
movable gripping member 11 made as a lug with the lower flat surface 
arranged parallel to the gripping member 12, i.e. to the flat portion of 
the second arm of the double-arm lever 17. For this, the gripping member 
11 is secured to the end of a rod 24 which passes through guides 25 on the 
double-arm lever 17 running along the second arm thereof. The rod 24 
carries a slide block 26 and a spring 27, one end of the spring 27 bearing 
against the slide block 26 and the other, against the guide 25 which 
renders the rod 24 spring-loaded. This spring 27 elastically tightens 
together the gripping member 11 and the gripping member 12. 
The rod 24 is placed in the guides 25 so that its end 28 protrudes 
therefrom, as is shown in FIGS. 1 and 4. This being the case, this 
protruding end 28 of the rod interacts with the stationary stop 13 to 
remove the gripping member 11 away from the gripping member 12. Due to 
such an arrangement of the gripping members 11 and 12, with the double-arm 
lever 17 turning, the gripping members 11 and 12, depending upon the 
profile of the stationary cam 21, either recede from, or advance to, the 
travelling-wave shed. 
The profiled surface of the stationary cam 21 represents a butt surface of 
this cam, as is shown in FIGS. 1 and 4, due to which the roller 20 of the 
double-arm lever 17 is in contact with the butt surface of the stationary 
cam. However, the profiled surface of the stationary cam 21 may be made as 
a shaped slot 29, as is shown in FIG. 5, on a cylindrical surface of the 
cam 21. In this case, the bush 14 is made as a sleeve with the stationary 
cam 21 placed therein. The shaped slot 29 of the cam 21 accommodates the 
roller 20 of the double-arm lever 17, with the axle 19 of the roller 20 
passing through a hole 30 (FIG. 6) made at the side of the flat 5 in the 
side surface of the bush 14. 
With the stationary cam 21 placed inside the bush 14, it is preferable that 
the double-arm lever 17 be shaped so as is shown in FIG. 6 and the contact 
of the stationary stop 13 with the spring-loaded rod 24 be attained via an 
intermediate rotatable member 31 with a rotational axle mounted on the 
double-arm lever 17 and combined with the axle 19 of the roller 20. 
Thereat, the rotatable member 31 (FIG. 6) has two arms 32 and 33, the arm 
32 cooperating with the end 28 of the rod 24 and the arm 33, with the 
abutment of the stationary stop 13. 
Intermediate of the travelling-wave shed A (FIG. 7) and the gripping 
members 11 and 12 mounted on the shaft 4 of the disk-type beat-up motion 
1, along an imaginary line D forming a continuation of the fell 9 of the 
cloth 10, there are located an additional gripping pair 34 of jaws 35 
(FIG. 8) and 36 and a cutter 37 (FIG. 7). 
The additional gripping pair 34 of the jaws and the cutter 37 are secured 
to a bracket 38 (FIG. 4) of the loom frame, the additional gripping pair 
34 of the jaws being designed for gripping the weft thread 7 forced to the 
fell 9 of the cloth 10 and held by the gripping members 11 and 12, with 
the cutter 37 adapted to sever the weft thread nipped by the additional 
gripping pair 34 of the jaws and the gripping members 11 and 12. 
The jaw 35 (FIG. 8) of the gripping pair 34 and a blade 39 (FIG. 9) of the 
cutter 37 are rigidly secured on the bracket 38 and are stationary. 
Since the jaw 36 of the gripping pair 34 and a blade 40 of the cutter 37 
are freely seated on a common axle 41 attached to the bracket 38 due to 
which they are allowed to turn about the axle 41, the jaws 36 and the 
blade 40 will be hereinafter referred to as movable. 
The movable blade 40 and the jaw 36 have the elongated shape, as is shown 
in FIGS. 8 and 9, terminating in abutments 42 and 43, respectively. 
The jaw 35 (FIG. 8) has a beveled 44 which allows a reliable contact of the 
jaw 35 over the beveled 44 with the appropriate portion of the jaw 36 so 
that gripping the weft thread is provided. 
The abutment 42 (FIG. 9) of the blade 40 carries a roller 45 which is free 
to rotate. The axle mounting roller 45 extends across the plane of 
abutment 43. 
The blade 40 and the jaw 36 are caused to rotate by a profiled cam 46 
attached to the shaft 4 of the disk-type beat-up motion and located nearer 
to the travelling-wave shed than the gripping members 11 and 12, as is 
shown in FIGS. 4 and 7. The profiled cam 46 (FIG. 9) is in constant 
contact with the roller 45 of the blade 40. For this, the rotatable blade 
40 is elastically urged against the profiled cam 46 by a bell crank lever 
47 and a tension spring 48. In this case, the bell crank lever 47 is 
seated on the axle 41 and one arm thereof is coupled, via a pin 49, with 
the blade 40 of the cutter, while the other arm, with the tension spring 
48 the other end of which is attached to a bell crank lever 50. 
The bell crank lever 50 is secured pivotably on an axle 51 available on the 
bracket 38 and intended for elastically tightening together the jaws 36 
and 35. With the jaw 36 elastically urged against the jaw 35 (FIG. 8), 
between the abutment 43 and the axle of the roller 45 formed is a gap 52 
ensuring the intimate contact of the jaws over the bevel 44 as well as the 
successive closing of the additional gripping pair 34 and the cutter 37. 
The weft thread gripping mechanism operates as follows. 
With the carriers 2 (FIG. 1) flying along the travelling-wave shed, unwound 
from the spools 8 of each of the carriers is the weft thread 7 which, 
nearby the rear wall of the carrier 2, is engaged by the teeth 6 of the 
disks 5 of the disk-type beat-up motion 1 and, with the shaft 4 rotating, 
these teeth 6 transfer the weft thread towards the fell 9 of the cloth 
thereby beating up the weft thread (the process of propulsing and beating 
up the weft thread being well known, it is not dealt with in the present 
description). As the carrier 2 emerges from the travelling-wave shed A, 
the gripping members 11 and 12 available on the double-arm lever 17, 
rotating together with the shaft 4 and disposed at the moment as close as 
possible to the travelling-wave shed come under the weft thread 7. As this 
takes place, the end 28 of the rod 24 rests against the stationary stop 
13, while the gripping member 11 is backed away from the gripping member 
12 so that a gap is formed therebetween and, at the next moment of 
rotation of the shaft 4, the weft thread 7 enters this gap, since the weft 
thread blocks the way of the moving gripping members 11 and 12. 
The double-arm lever 17 (FIG. 4), therewith, acted upon by the spring 23 
and the stationary cam 21 which is in permanent contact with the roller 20 
of the double-arm lever 17, starts turning in the direction shown by an 
arrow E in which the gripping members 11 and 12 recede from the looming-up 
zone, i.e. from the travelling-wave shed. The end 28 of the rod 24 leaves 
the stop 13 and under the action of the spring 27 the gripping member 11 
is urged against the gripping member 12 thereby gripping the weft thread 
seized by them. 
Now, the double-arm lever 17, while continuing rotating together with the 
shaft 4 and pivoting under action of the spring 23, removes the excess 
amount of the weft thread from the looming-up zone. Before the position of 
the weft thread withdrawn from the warp threads coincides with the 
imaginary line D (FIG. 7) forming the continuation of the fell 9 of the 
cloth 10, the cutter 37 and the jaws 35 and 36 of the additional gripping 
pair 34 open. To this end, the profiled cam 46 (FIG. 9) rotating together 
with the shaft 4, exerts pressure on the roller 45 and causes the movable 
blade 40 of the cutter to turn relative to the axle 41 and the stationary 
blade 39. As the roller 45 goes on displacing under action of the cam 46, 
the axle thereof approaches the abutment 43 of the movable jaw 36, turns 
this jaw 36 with respect to the axle 14 and makes it move away from the 
stationary jaw 35. 
At the next moment of rotation of the shaft 4, the weft thread 7 nipped at 
one end by the gripping members 11 and 12 proves to be on one line with 
the fell 9 of the cloth 10, i.e. coincides with the line D, enters the 
gaps between the jaws 35 and 36 of the additional gripping pair and the 
blades 39 and 40 of the cutter 37. 
Next, in accordance with the change of the profile of the cam 46, the 
roller 45 departs from the abutment 43 of the movable jaw 36 and the 
latter, while being acted upon by the bell crank lever 50 and the spring 
48, turns and causes the weft thread to urge against the jaw 35. 
Thereafter, the movable blade 40, under the action of the bell crank lever 
47 and the spring 48, turns and cuts the weft thread nipped by the jaws 35 
and 36 of the additional gripping pair 34 and the gripping members 11 and 
12. 
Following this, in accordance with the change of the profiled surface of 
the stationary cam 21, the double-arm lever 17 starts turning in the 
reverse direction, thereby approaching the looming-up zone. As the 
double-arm lever 17 turns, the end 28 of the rod 24 starts interacting 
with the stationary stop 13, the spring 27 compresses and the gripping 
member 11 departs from the gripping member 12, whereby the cut-off end of 
the weft thread is released and the gripping members 11 and 12 prove to be 
ready for seizing the next weft thread brought by the carrier emerging 
from the shed. 
The whole process described above takes place while the shaft 4 makes one 
revolution. Then, the cycle repeats itself.