Weaving loom

A weaving loom is equipped with a system for controlling oscillation of a warp yarn support roller in which a first rotary cam actuates an oscillating first lever connected to a first arm integral with a first shaft on which the roller is mounted. The first shaft rests, through the intermediary of raising members, in bearings supported by second levers pivoting about a fixed pivot and connected, through the intermediary of pivoted connecting rods, to the third and fourth levers which are keyed to a second shaft and subject to urging by at least one spring. The system includes a fifth lever keyed to the second shaft and a second rotary cam actuating an oscillating sixth lever pivotably connected to a second arm which is alongside the fifth lever and is freely mounted on the second shaft. A fixed first hook is mounted on the second arm and a pivotable second hook is mounted on the fifth lever. An electromagnet holds the second hook clear of the first hook except when the loom is being started. In this event the second cam causes the second arm to pivot downwards about the second shaft so that the first hook pushes the second hook downwards causing the fifth lever to pivot downwards and rotate the second shaft. This rotation throws the connecting rods which pivot the second levers which move the support roller transversely to warp yarn passing thereover to increase tension in the yarn.

Field of the Invention 
This invention relates to a weaving loom provided with a device to 
eliminate differences in the warp yarn characteristics at the time of 
starting-up the loom. 
BACKGROUND OF THE INVENTION 
A loom can be provided with a system for controlling the oscillation of a 
yarn support roller comprising, on at least one side of the loom, a rotary 
cam actuating an oscillating lever connected to an arm integral with the 
shaft of the yarn support roller. This shaft rest, through the 
intermediary of raising members, in bearings supported by levers pivoted 
about a fixed pivot point and is connected, through the intermediary of a 
connecting rod, to another lever keyed on a shaft subject to the action of 
at least one spring. When the loom is operated continuously, this known 
system makes it possible to cause the axis of the yarn support roller to 
oscillate, in order to absorb the alternating phenomenon of excess tension 
or slack of the warp yarns caused by the opening or closing movement of 
the two sheds in the weaving process, this slack take up taking place 
while ensuring tensioning of the yarn by virtue of the spring. 
However, at the time of re-starting the loom after a stoppage, the system 
in question does not make it possible to eliminate differences in the 
warp, i.e. differences in the number of warp threads per unit length, 
which create defects in the fabric, which defects are well-known to 
persons skilled in the art and are known as "thin spots", "marks" or 
"flaws". No device currently exists for preventing these defects, in high 
speed looms. 
OBJECTS OF THE INVENTION 
It is the object of the present invention to obviate this shortcoming. 
SUMMARY OF THE INVENTION 
According to the invention there is provided a weaving loom having a system 
for controlling oscillation of a warp yarn support roller comprising, on 
at least one side of the loom, a rotary first cam mounted on a first shaft 
acutating an oscillating first lever connected to an arm integral with a 
second shaft. The yarn support roller is mounted on a second shaft 
resting, through the intermediary of a raising member in a bearing 
supported by a second lever pivoted about a fixed pivot and connected 
through the intermediary of a connecting rod to a third lever keyed to a 
third shaft subject to the action of at least one spring. 
The system including a device for preventing differences in warp yarn at 
the time of starting up the loom. 
This device comprises a second rotary cam mounted on the first shaft and 
actuating an oscillating fourth lever connected to a pivoted arrangement, 
a fifth lever keyed to the third shaft subject to the action of the 
spring, hooking means controlled by an electromagnet being provided so 
that said fifth lever is entrained at the same time as an element of the 
pivoted arrangement upon starting up the loom. The said connecting rod 
changes the position of the bearing for the oscillation of the second 
shaft carrying the yarn support roller in a direction corresponding to 
additional tension on the warp yarn. 
Thus, the device, in a loom formed according to the invention, is attached 
to the system for the oscillation of the yarn support roller and at the 
time of starting-up the loom, creates an additional movement of the second 
shaft carrying said roller which, by applying greater tension to the warp 
yarns, prevents differences in the weft. 
The device may be provided either on only one side of the loom, or on both 
sides of the loom. In the first case, the fact that the third shaft on 
which the fifth lever is keyed, passes through the entire loom, allows the 
single device to move the second shaft by its two ends. 
In a preferred embodiment the pivoted arrangement comprises a pulling rod 
pivotably connected to the oscillating fourth lever and to one end of said 
element comprised by an oscillating second arm. The other end of said 
second arm is freely rotatable about the third shaft and the hooking means 
comprises first and second hooks, the first hook being mounted on said 
second arm while is stationary relative thereto, and the second hook is 
mounted on the fifth lever and is pivotable relatively to said fifth lever 
which also supports the electromagnet. Depending on whether the latter is 
or is not supplied with current, the trajectory of one of the hooks 
encounters or does not encounter the other hook which makes it possible, 
by means of an adequate control of the supply of power to the 
electromagnet, to obtain hooking at the time of starting-up, in order to 
set the fifth lever in rotation, this hooking being initiated as soon as 
the loom is stopped. 
Advantageously, the oscillating second arm is pivoted to a stirrup member 
mounted to slide on the pulling rod but normally bearing, under the effect 
of resilient means, against an adjustable stop supported by the pulling 
rod. The possibility of adjusting the device is thus provided and 
furthermore, the resilient means which may be, for example, in the form of 
a stack of elastically yieldable washers ensures a damping and safety 
function, thus preventing the direct connection between the pulling rod 
and the oscillating second arm.

SPECIFIC DESCRIPTION 
The drawing shows, very diagrammatically, a frame 1 of a loom as well as a 
beam 2 from which warp threads 3 unwind and a yarn support roller 4 over 
which the warp threads 3 pass, before forming a substantially horizontal 
shed which then divides into two sheds 3a and 3b. The beam 2 and the 
roller 4 rotate about horizontal and parallel axes respectively 5 and 6, 
located in the rear part of the loom. 
The complete system in question is composed of two mechanisms 7 and 8, 
located respectively on the two sides of the loom, in the vicinity of the 
ends of the beam 2 and of the yarn support roller 4. These two mechanisms, 
which have similar parts but are not identical, are illustrated 
respectively in FIGS. 2 and 3. 
The mechanism 7, which is visible in FIG. 2, comprises a case 9, integral 
with the frame 1 of the loom, inside which are mounted two rotary cams 10 
and 11, keyed on the same shaft 12 parallel to the axes 5 and 6. 
At the time of continuous operation, the first cam 10 makes it possible to 
control the oscillation of the yarn support roller 4, this being through 
the intermediary of an oscillating lever 13. This lever is pivoted to the 
casing 9 about an intermediate fixed pivot 14. A roller 15, mounted to 
rotate freely about a shaft 16 located at one end of the lever 13, travels 
along the profile of the cam 10. A spring 17, stretched between a point 18 
of the lever 13 and a fixed point which is not shown in FIG. 2, 
permanently presses the roller 15 against the cam 10. At its opposite end 
to the roller 15, the lever 13 comprises a flat surface 19 directed 
upwards, against which a block 20 of a material having a low coefficient 
of friction is pressed and is able to slide. 
The said block 20 is connected to the shaft 21 of the yarn support roller 4 
through the intermediary of an arm 22 of adjustable length, formed by the 
comination of two parts. The first of these parts 23 is a straight flat 
bar, at one end of which the block 20 is mounted to pivot and retained by 
means of a screw/nut arrangement 24. Over its entire length, this flat bar 
comprises tapped holes 25 at regular intervals. The second part 26 of the 
arm 22 has a cranked shape. One of its sides is provided with slots 27. 
Screws 28, passing through these openings 27, are screwed into the holes 
25 in the part 23 and connect the latter to the part 26, whilst allowing 
the length to be adjusted. The part 23 and the side in question of the 
part 26 are thus connected one as an extension of the other. The other 
side of the part 26, located beyond the crank in the latter, is directed 
upwards and at its upper end is secured by gripping to the shaft 21 of the 
yarn support roller 4, by means of a screw 31, in order to prevent any 
rotation of this shaft 21 with respect to the part 26. 
Fixed on the shaft 21, at some distance from the part 26, is a raising 
member 32 which itself is also prevented from rotating with respect to the 
shaft by means of a clamping screw 33. In its lower part, the raising 
member 32 supports a small shaft 35 able to oscillate in a bearing 36, 
which is supported by a lever 37 of general concave shape. 
This lever 37 is pivoted by its upper end about a pivot 38, on a support 39 
integral with the frame 1 of the loom. In its lower half, the lever 37 
comprises a plurality of holes 40, passing through one of which is a pivot 
pin 41 about which an end of a connecting rod 42 is pivoted. The other end 
of the connecting rod 42 is pivoted about a pivot pin 43, to another lever 
44 keyed on a shaft 45, which is mounted to rotate in the support 39 and 
passes through the entire loom. 
In the vicinity of the lever 44, the shaft 45 supports another lever 46, 
the end of which is pivoted about a pivot pin 47, to a screw-threaded rod 
48 which is subject to the thrust of a large spring 49, which bears on a 
part 50 projecting from the support 39. 
Part of the afore-described members also exist in the mechanism 8 located 
on the other side of the loom and shown in FIG. 3. A support 39', similar 
to the support 39, facilitates the pivoting of a lever 37', which is 
symmetrical with respect to the lever 37, about a pivot pin 38'. The lever 
37' supports a bearing 36' on which a shaft 35' supported by a raising 
member 32' is able to oscillate. The raising member 32' is connected to 
rotate with the shaft 21 of the yarn support roller 4, in the same manner 
as the raising member 32 located on the other side, by means of a clamping 
screw 33'. A connecting rod 42' is also provided, one end of which is 
pivoted to the lever 37', about a pivot pin 41' corresponding to a hole 
40' in the said lever and the other end of which is pivoted to another 
lever 44' about a pivot pin 43'. Like the lever 44, the lever 44' is keyed 
on the shaft 45 which, passing through the loom, is also mounted to rotate 
in the support 39'. Finally, a last lever 46', also keyed on the shaft 45, 
is pivoted about a pivot pin 47', to a screw-threaded rod 48' subject to 
the thrust of a large spring 49' which bears on a projecting part 50' of 
the support 39'. On the other hand, on this side in question, neither cams 
nor members corresponding to the lever 13 and to the arm 22 located on the 
other side of the machine, are provided. 
The device to which the present invention relates specifically is 
associated with the single mechanism 7 located on one side of the loom and 
illustrated in FIG. 2. This device, also illustrated separately in FIG. 4, 
comprises a cranked lever 51, pivoted to the casing 9 about a fixed pivot 
52 located in the region of its crank. A roller 53 is mounted to rotate 
freely at the end of one of the two sides of the lever 51 and it travels 
along the profile of the second cam 11. A spring 54, stretched between a 
fixed point 55 located on the side of the casing 9 and a sleeve 56 
connected in a rotary manner to the cranked lever 51, permanently presses 
the roller 53 against the cam 11. 
The end of the second side of the cranked lever 51 is pivoted, about a 
pivot pin 57, to the lower end of a substantially vertical pulling rod 58, 
which supports a stirrup member 59. The latter is mounted to slide on the 
rod 58 but it normally bears against a stop 60 fixed by gripping in an 
adjustable position on the rod 58, by means of a screw 61. A stack of 
elastically yieldable washers 62 is placed around the rod 58 between the 
stop 60 and the socket 63 connected to one end of the stirrup member 59, 
in order to press the other end of the stirrup member against the stop 60. 
Pivoted to the upper part of the stirrup member 59, about a pivot 64, is 
one end of a double oscillating arm 65, the other end of which rotates 
freely about the shaft 45. The double oscillating arm 65 thus forms a type 
of substantially horizontal connecting rod, comprising a recess at its 
centre, FIG. 4 showing this connecting rod with its front part removed in 
order to reveal the elements located between the front part and the rear 
part, in the central recess. 
On the one hand, these internal elements comprise a "fixed" hook 66 
connected by two secrews to the double arm 65, in the vicinity of the 
pivot 64 for the stirrup member 59 and on the other hand, a lever 67 keyed 
on the shaft 45. Mounted at the free end of the lever 67, located in the 
vicinity of the fixed hook 66, is a "movable" hook 68, which is able to 
pivot about a pivot pin 69 with respect to the end of the lever 67. The 
movable hook 68 comprises a control finger 70 and it can be actuated by 
means of an electromagnet 71, fixed by means of a U-shaped support 72 to 
the upper side of the lever 67. When the electromagnet 71 is excited, its 
movable core 73 is attracted and it retracts, allowing the movable hook 68 
to pivot in clockwise direction, with reference to FIG. 2 or 4, under the 
action of a control spring 74 stretched between the finger 70 and a point 
75 located on the side of the lever 67. When the electromagnet 71 is not 
excited, its movable core 73 emerges, under the thrust of a spring 76 and 
it pushes the control finger 70 of the movable hook 68 in order to pivot 
the latter in counter-clockwise direction, against the pulling force 
exerted by the spring 74 (the effect of the srping 76 prevailing over that 
of the spring 74). 
At the time of continuous operation, the rotation of the first cam 10 
causes the oscillation of the lever 13 about its pivot 14. This 
oscillation movement causes an alternating movement of the arm 22, the 
block 20 sliding, in the manner of a shoe, on the surface 19 of the lever 
13. This results in an oscillating movement, on the bearings 36 and 36', 
of the rigid arrangement constituted by the arm 22, the shaft 21 of the 
yarn support roller 4 and the two raising members 32 and 32'. The axis of 
oscillation of this arrangement during continuous operation is fixed. In 
fact, the electromagnet 71 remains non-excited, so that, despite the 
permanent oscillation of the double arm 65 controlled by the second cam 
11, the movable hook 68 does not co-operate with the fixed hook 66, the 
trajectory of the hook 66 not encountering the hook 68. Thus, the lever 67 
retains a position independent of that of the double arm 65. The rigid 
arrangement formed by this lever 67, the shaft 45, the two levers 46 and 
46' and the two levers 44 and 44' thus occupy the position determined 
solely by the thrust of the two springs 49 and 49'. As a result of the 
connection achieved with this arrangement by means of the connecting rods 
42 and 42', the two levers 37 and 37', supporting the respective bearings 
36 and 36', remain stationary and define a fixed oscillation axis for the 
shaft 21 of the yarn support roller 4. 
Although at the time of continuous operation, the mechanism controlled by 
the cam 11 does not intervene, one should understand that this cam causes 
a permanent oscillation of the double arm 65. Thus, at the time when the 
larger diameter part of the cam 11 co-operates with the roller 53, the 
cranked lever 51 pivots in the direction indicated by arrow 77 and it 
pulls the rod 58 downwards in the direction of arrow 78 (c.f. FIG. 4). The 
rod 58 pulls the stirrup member 59 downwards, as well as the end of the 
double arm 65 pivoted to said stirrup member. The double arm 65 thus 
pivots downwardly about the shaft 45. At the time when the loom is 
stopped, by actuating the braking system of the latter, the electromagnet 
71 is excited simultaneously, so that the movable hook 68 is moved to a 
position in which the trajectory of the hook 66 encounters this hook 68. 
Consequently, during its last descending movement before the loom is 
stopped, the fixed hook 66 co-operates with the movable hook 68. Thus, the 
lever 67 will be forced to follow the pivotal movement of the double arm 
65, so that the rigid arrangement formed by this lever 67, the shaft 45 
and the levers 44, 44', 46 and 46' tends to pivot, in the direction 
indicated by arrow 80. 
At the time of re-starting the loom, the electromagnet 71 is de-energised, 
but the two hooks 66 and 68 remain temporarily hooked to each other, so 
that the action on the shaft 45 previously initiated and described above, 
is maintained. Thus, the movement of the two levers 44 and 44' causes the 
two connecting rods 42 and 42' pivoted thereto, to move forwards, in the 
direction of the respective arrows 81 and 81' (c.f. FIGS. 2 and 4). The 
two levers 37 and 37', supporting the bearings 36 and 36', thus pivot in 
the direction of the respective arrows 82 and 82' about pivots 38 and 38', 
so that the yarn support roller 4 is pushed in the direction of arrow 83 
and causes the desired effect, namely producing additional tension on the 
warp threads 3 which prevents differences in the weft at the time of 
starting-up. 
As the first operating cycle of the loom continues, at a given instant, the 
hook 66 arrives in a position higher than the hook 68, so that the latter 
is automatically released and resumes its initial position under the force 
of the spring 76, transmitted by the core 73 of the electromagnet. The 
entire device thus operates continuously, as described above. 
It should be noted that the special structure of the pulling rod 58 and of 
the stirrup member 59 allows double adjustment and ensures a damping and 
safety function, for the correct operation of the device according to the 
invention. By moving the adjustable stop 60 along the rod 58, the mean 
position of the double oscillating arm 65 is adjusted. By screwing the 
socket 63, which has an external screw-thread, to a greater or lesser 
extent into the stirrup member 59, the compression of the elastically 
yieldable washers 62 is adjusted. The latter ensure the damping and safety 
function, by being compressed if the stirrup member 59 encounters a 
certain resistance preventing it from following the movement of the 
pulling rod 58. 
The device eliminating differences in the warp at the time of starting-up, 
can be applied to looms of all types, both conventional looms as well as 
shuttleless looms.