Heald control system for a travelling wave shedding loom

A heald control system for a multi-phase or travelling wave shedding loom in which each heald is upperly connected elastically, by way of an elastic traction element, to a single support plate which is removably locked to the fixed part of the loom, and the healds of each section are lowerly locked to a single connection block which is connected by a spring catch connector to a flexible element, which is itself connected to the end of a cam-controlled operating lever.

BACKGROUND OF THE INVENTION 
This invention relates to an improved heald control system, particularly 
suitable for multi-phase or travelling wave shedding looms. The invention 
which eliminates any cause of warp thread wear and which is of very low 
inertia, is of highly reliable operation at the high speeds required of 
modern textile looms. 
Moreover, by allowing simple and rapid removal and installation of the 
entire heald assembly on the loom, said control system extremely 
facilitates the heald setting operation, which can now be done outside the 
machine, thus enabling this latter to continue to operate in the meantime 
with another harness (heald assembly). In both single-phase and 
multi-phase looms for weaving by weft and warp interweaving, the opening 
of the warp threads in order to form the shed into which the weft thread 
to be interwoven is inserted is effected by the vertical movement in 
opposite directions of two sets of healds. The healds include eyes through 
which pass said warp threads, one per eye. However, in the case of 
single-phase looms the moving of the healds in order to form a single shed 
is fairly simple, since all the healds of the two sets are moved 
simultaneously over the entire weaving height. This is no longer true in 
the case of multi-phase or travelling wave shedding looms in which the 
shed opening must take place in front of each of the weft inserters which 
move along the weaving zone, and must proceed in phase with these. There 
is therefore not a single open shed but instead a number of sheds equal to 
the number of weft inserters present in the weaving zone. Consequently the 
healds of each set must be arranged in the form of waves which travel 
synchronously with said weft inserters. 
The state of the art already comprises various known types of heald control 
systems for effecting travelling wave opening, which is a characteristic 
of the multi-phase technology. These known control systems are all based 
on dividing the entire warp thread assembly and consequently the healds 
into a succession of small side-by-side sections. These sections behave 
like the frames of a conventional loom are moved mutually out of phase by 
a predetermined angle, so as to give rise to the required travelling wave 
shedding. 
In a known construction, each of said sections is constituted substantially 
by two horizontal heald support arms which together with two vertical rods 
form a rigid rectangular frame of elongated shape. 
However, such a design has considerable drawbacks. Firstly, the rigidity 
and consequently non-negligible weight of the frames lead to substantial 
inertial forces as a result of the reciprocating motion of the masses 
concerned, thus making this construction unsuitable for high-speed 
operation. In addition, the presence of the vertical rods of the aforesaid 
frames in the warp thread field creates interference with the warp threads 
and between the warp threads themselves in the zone surrounding said rods. 
This interference obstructs the crossing-over of said threads, therefore 
leading to damaging wear in the thread with consequent increase in the 
harmful and costly shut-downs of the loom due to thread breakage. Again, 
said vertical rods obstruct the weaving height, and reduce the maximum 
obtainable warp density. 
In another known construction, said sections include a single vertical rod 
provided with small transverse arms suitably disposed for carrying the 
healds. 
Although this known construction is of smaller mass and therefore smaller 
inertia, it however suffers from substantially the same drawbacks as the 
preceding construction. 
The object of the present invention is to obviate the aforesaid drawbacks 
and thus provide a heald control system for a multi-phase loom which is of 
low energy consumption by virtue of its small inertia. The heald control 
system acts on the warp threads in such a manner as to enable them to 
undergo minimum possible wear during cross-over, and enables high warp 
densities to be obtained. 
SUMMARY OF THE INVENTION 
In a heald control system for a multi-phase loom comprising two or more 
corresponding sets of healds moved vertically in mutual opposition, the 
healds of the two sets are divided into corresponding side-by-side 
sections which follow each other and which are moved out of phase with 
each other by a predetermined angle. Each section is moved by a 
cam-controlled operating lever, each individual heald is connected upperly 
to a single support plate by means of its own elastic traction element, 
and the healds of each section are lowerly locked to a single connection 
block connected by a flexible element to the end of a cam-controlled 
operating lever. 
In this manner, the healds are always elastically under tension and are 
therefore made substantially rigid without the need for a rigid and thus 
heavy support structure. 
Furthermore, their inertia is made even smaller by the use of said 
connection blocks. The connection blocks do not directly connect all the 
healds to their relative operating levers. A single flexible wire or 
element is sufficient for each section. In addition, the absence of 
elements which obstruct the weaving height both prevents warp thread wear 
by rubbing and enables high warp densities to be obtained. 
In order to allow rapid and simple replacement of the heald assembly, 
according to a further characteristic of the present invention, said 
single support plate is removably locked to the fixed part of the loom. 
Said connection blocks are connected to the respective flexible elements 
by a spring catch connector. 
A further characteristic of the present invention is that said connection 
blocks comprise vertical guide channels into which the lower ends of the 
healds of the section are inserted and are locked there by a transverse 
plate which is inserted into slots present at said heald ends. 
In this manner, simple extraction of said transverse plate simultaneously 
releases all the healds of one section from the respective connection 
blocks, while the vertical guide channels in the block ensure uniform 
distribution of the healds. This arrangement prevents the healds from 
becoming grouped on a single side of the block. 
According to a further characteristic of the present invention, the two 
operating levers for the healds of two corresponding sections are 
controlled by the same cam. The levers are each held against the cam. 
This leads to considerable simplification, with obvious economic 
advantages. Indeed, in order to further increase simplification, according 
to a further modification of the present invention, two operating levers 
are held against the control cam by a single spring acting between said 
two levers.

DETAILED DESCRIPTION OF THE INVENTION 
In the figures, the reference numeral 1 indicates the reed of the 
multi-phase loom, the purpose of which is to beat the weft threads against 
the fell 2.sub.1 of the fabric under formation 2. The weft threads are 
inserted in succession by suitable shuttles into the sheds formed by the 
warp threads 3. The warp threads 3 originate from a beam not shown in the 
figure. The warp threads pass through the eyes 4.sub.1 and 5.sub.1 of two 
corresponding opposing sets of healds. The healds are divided into 
corresponding successive side-by-side sections 6.sub.1 and 7.sub.1, 
respectively. The section 6.sub.1 includes the healds associated with the 
connection block 14.sub.1 and the section 7.sub.1 includes the healds 
associated with connection block 15.sub.1. Likewise section 6.sub.2, 
6.sub.3, 7.sub.2, and 7.sub.3 are associated with the connection blocks 
14.sub.2, 14.sub.3, 15.sub.2 and 15.sub.3, respectively. The eyes 4.sub.1, 
4.sub.2, 4.sup.3 are similarly associated with sections 6.sub.1, 6.sub.2 
and 6.sub.3 and the eyes 5.sub.1, 5.sub.2, 5.sub.3 are similarly 
associated with the sections 7.sub.1, 7.sub.2, 7.sub.3, respectively. 
respectively. Each individual heald of the sections 6.sub.1 and 7.sub.1 is 
connected upperly, by way of its own elastic traction element 8.sub.1 and 
9.sub.1, to a single support plate 10 which is removably fixed by bolts 11 
to the fixed part 12 of the multi-phase loom. All the healds of the 
sections 6.sub.1 and 7.sub.1 insert their lower ends into vertical guide 
channels 13 present in corresponding connection blocks 14.sub.1 and 
15.sub.1, respectively. The healds 14.sub.1 and 15.sub.1 are locked there 
by a transverse plate 16 which is inserted into the slots 17 present at 
said lower ends of the healds (see FIG. 4). The connection blocks 14.sub.1 
and 15.sub.1 are themselves releasably locked, by a spring catch connector 
18, to corresponding flexible elements or wires 19.sub.1 and 20.sub.1 
which connect them to the end of underlying operating levers 21.sub.1 and 
22.sub.1. The operating levers 21.sub.1 and 22.sub.1 are pivoted 
respectively on two shafts 23 and 24 supported by the fixed part 25 of the 
loom. The pairs of levers 21.sub.1, 22.sub.1 ; 21.sub.2, 22.sub.2 ; . . . 
which operate the healds of two corresponding sections 6.sub.1, 7.sub.1 ; 
6.sub.2, 7.sub.2 ; . . . are controlled by the same cam 26.sub.1, against 
which they are each held by their own spring 27 (see FIG. 1). According to 
a modification of the invention, said pairs of levers are held against 
their respective control cam by a single spring 28 (see FIG. 2) acting 
between said levers of the individual pairs. Said operating cams 26.sub.1 
for the corresponding pairs of levers are all fixed to one shaft 29, and 
are mutually offset by a predetermined angle so as to cause said blocks 
14.sub.1 and 15.sub.1 to assume a wave arrangement. This arrangement gives 
rise to the required travelling wave shedding.