Spring attachment for negative dobbies

In a spring system for dobbies and other weaving mechanisms of the negative type which includes hooking elements, each of the hooking elements includes, parallel to its edges which face the springs, a row of omega-sectioned openings which receive, by a lateral displacement along the axis of the opening, an endpiece of a shape to be seated within the openings.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to dobbies and other weaving mechanisms of 
the negative type for forming the shed in weaving looms, and more 
particularly to the spring systems which, in this type of mechanism, 
ensure return of the heddle frames. 
2. History of the Related Art 
Mechanisms of the negative type are known to operate positive control of 
the heddle frames acting only in one direction of the reciprocating stroke 
thereof, so that resilient elements should be provided, arranged so as to 
return the frames to the other end of the stroke. These resilient elements 
are most often constituted by two systems formed by parallel springs 
retained between two hooking elements of which one is mounted on a console 
or rack secured to the fixed structure of the loom, while the other is 
hooked either to the end of one of two cables provided for maneuvring each 
frame, or to a rocking guide lever associated with the cable. 
It will be readily appreciated that the springs of each spring system are 
thus placed in tension during positive control of a frame by the weaving 
mechanism so that as the mechanism has arrived at the end of stroke the 
spring system will act on the cable or lever to return the frame to its 
initial position. 
In practice and as illustrated in FIG. 1 of the accompanying drawings, each 
hooking element generally includes two parallel plates a assembled to one 
another by transverse ties b which are fixed by rivetting or crimping. For 
fastening the springs c, endpieces d in the form of hooks are 
conventionally provided and are adapted to cooperate in a removable manner 
with one of a row of small rods e rivetted on the plates a in a line 
oriented perpendicularly to the axis of the springs. 
The prior art is illustrated by documents DE-A-3 533 336 (MURATA KIKAI), 
FR-A-2 626 013 (STAUBLI), GB-A-298 758 (HARLING and TODD) and EP-A-353 875 
(YOKOI INDUSTRIES). 
It should be observed that, due to the high operational speeds now 
conferred on weaving machines, more and more considerable forces are 
demanded of the spring systems, with the result that the springs break 
relatively frequently. Now, although it is fairly easy to replace a broken 
spring when the operation concerns one of the two side systems of the 
group of spring systems provided on one of the sides of a group of heddle 
frames. This is not so when it is question of extracting a broken spring 
and mounting a new one in the interior systems of the group. In fact, 
replacement involves dismantling and remounting a large number of systems 
and springs, all of which are in addition subjected to very high tension. 
Furthermore, it is of interest to note that, due to their configuration, 
the hooks which connect the springs on the hooking elements, are subject 
to bending forces and are consequently the location of frequent breaks 
which stops the operation of a weaving machine. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to overcome the drawbacks set 
forth hereinabove by providing a spring system for dobbies and other 
weaving mechanisms of the negative type, which includes at least one 
hooking element on which are hooked endpieces provided at the ends of a 
series of parallel springs, characterized in that the hooking element is 
provided, at its edge facing the springs, with a series of openings of 
omega shape or profile which open out via a narrowed part on the edge 
thereof and which open freely on the lateral faces thereof in order to 
allow assembly and dismantling, by lateral access, of the endpieces fixed 
to the ends of these springs. The endpieces are thus suitably retained in 
place inside the omega openings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring again to the drawings, reference 1 in FIG. 2 designates one of 
the heddle frames which are mounted on a weaving loom and of which each is 
moved vertically by two cables 2. One of the ends of each cable 2 is 
attached to one of the levers of a dobby or other mechanism, while the 
opposite end is guided by a rocking lever 3 mounted idly on a horizontal 
shaft 4 carried by the fixed structure 5 of the loom. The free end of the 
cable 2, fixed to the lever 3 at 3a, is coupled to a return spring system 
6 formed by a plurality of vertical springs 7 of which the ends are 
secured to two hooking elements 8. The upper hooking element 8 is fixed to 
the end of the cable 2 so as to move vertically therewith, while the lower 
hooking element 8 cooperates with a rack 9 secured to the fixed structure 
5. 
As shown in FIGS. 3 and 4, each hooking element 8 is includes a relatively 
thick monobloc piece which may be directly obtained by cut-out/stamping to 
obtain the triangular profile visible in FIG. 2. On the horizontal edge 
which faces the springs 7, each hooking element 8 has a series of openings 
8a cut out therein, in a number equal to that of said springs. FIG. 3 
shows the omega section of each opening 8 which is open on the opposite 
lateral faces of the hooking element 8 and which opens out on the free or 
outer edge 8' thereof by a passage 8a' of reduced section. 
Each of the ends of each spring 7 receives an endpiece 10 made of synthetic 
material and arranged to be cooperate seated within one of the omega 
openings 8a of one or the other of the two hooking elements 8. Each 
endpiece 10 includes a principal body 10a which is connected at one end 
with a cylindrical base 10b provided to be threaded in order to screw into 
the end of a spring 7 and on the other end with a thin neck 10c secured to 
a semi-cylindrical stop 10d which is provided with a deformable tab 10e. 
It will be observed that the stop 10d includes two projections 10f which 
extend laterally thereof. 
The endpiece 10 may be dimensioned so that the stop 10d engages in an 
opening 8a by lateral introduction from one or the other of the faces of 
the hooking element 8 shown. The neck 10c fits in the narrowed passage 8a' 
of the opening 8a. Removal of the endpiece in the horizontal direction is 
prevented by clipping projections 10f against the lateral faces of the 
hooking element, in the vertical direction by the pad 10e bearing against 
the part of the wall defining the opening 8a which is opposite the 
narrowed passage, as clearly illustrated in FIG. 4. 
The removal of a broken spring and replacement by a new spring may be very 
easily accomplished even when the replacement concerns a system 6 which is 
located inside the group of systems provided on each side of the loom. The 
lateral movement of removal or positioning of an endpiece 10 in an opening 
8a may effectively be obtained without it being necessary to dismantle and 
subsequently remount springs other than the one which requires 
replacement. 
It will be observed that the endpieces 10 have a symmetrical section which 
avoids any bending effort. These endpieces are solely subject to traction 
forces along their axis and consequently provide, with equal space 
requirement, an increased resistance with respect to the conventional 
hook-shaped endpieces. 
It will be readily appreciated that the precise section of each endpiece 10 
may vary to a certain extent as long as it retains the corresponding 
spring and its positioning and removal may be obtained by a horizontal 
movement along the axis of the omega-sectioned opening 8a.