Multi-axial yarn structure forming machine

Details Multi-axial yarn structure forming machine Multi-axial yarn structure forming machine

2000-04-12

2001-05-29

Calvert, John J. (Department: 3653)

Textiles: weaving

Special-type looms

C139SDIG001

Reexamination Certificate

active

06237643

ABSTRACT:

The present invention relates to a machine for forming a multi-axial yarn structure and particularly to a machine having a bias yarn assembly forming means for forming from warp yarns fed in a warp feed direction in the form of a warp sheet a non-woven bias yarn assembly comprising two superposed bias yarn sub-assemblies in which the bias yarns of one sub-assembly are inclined to the bias yarns of the other sub-assembly and in both of which the bias yarns are inclined to the warp feed direction.
A simple form of multi-axial yarn structure embodying a non-woven bias yarn assembly is shown in FIG.
1
. The non-woven bias yarn assembly is composed of two superposed non-woven diagonal sub-assemblies of warp yarns
11
and
12
arranged at angles of ±45° to the reference warp direction R, a binding warp yarn assembly comprising binding warp yarns
13
extending in the warp feed direction and passing through the non-woven diagonal warp yarn sub-assemblies
11
and
12
, an upper weft yarn assembly comprising weft yarns
14
and a lower weft yarn assembly comprising weft yarns
15
.
The structure illustrated in
FIG. 1
can be produced on a multi-axial yarn structure forming machine previously proposed in International patent application No. PCT/GB94/00028 (publication WO94/16131) and illustrated in outline in FIG.
2
A. The machine comprises a creel
16
which supplies warp yarns in a warp sheet
17
in a warp feed direction F to a yarn transfer mechanism
18
following passage through yarn support elements
19
of a jacquard mechanism
20
. Each warp yarn of the warp sheet
17
is supported by its own yarn support element
19
which can be raised and lowered under the control of the mechanism
20
to form sheds in which warp yarns of the warp sheet
17
are raised. Such mechanisms are well known in the art and can be used for making complex selections for the shedding of the warp sheet in the formation of fabrics of intricate pattern. The mechanism provided in the machine illustrated in
FIG. 2A
is employed also for raising and lowering warp yarns of the warp sheet
17
during yarn transfer carried out by the yarn transfer mechanism
18
.
The yarn transfer mechanism
18
shown more clearly in
FIG. 2B
comprises a lower yarn guide member
21
which extends in the weft direction throughout the width of the warp sheet
17
and includes upstanding yarn guide elements
26
which (i) extend through the thickness of the warp sheet
17
, (ii) define warp yarn guide openings
27
through which the warp yarns of the warp sheet
17
pass and (iii) hold the warp yarns in predetermined positions spaced apart in the weft direction and a warp yarn transfer member
22
which also extends in the weft direction and which includes spaced yarn guide elements
28
defining transfer openings
29
for the reception of yarns of the warp sheet
17
for transfer in the weft direction to produce the bias warp yarns
11
and
12
which are to form part of the yarn structure produced on the machine.
The yarn transfer mechanism
18
in the machine illustrated in
FIGS. 2A and 2B
subjects the warp yarns of the warp sheet
17
to successive bias yarn forming steps in which each yarn is caused to move in a succession of lateral transfer steps in a first weft direction from a first bias yarn reversal position to a second bias yarn reversal position and then to move in a succession of return lateral transfer steps in the opposite direction from the second bias yarn reversal position to the first bias yarn reversal position thereby to form two superposed non-woven bias yarn sub-assemblies as shown in
FIG. 1
, the bias yarns
11
of one sub-assembly being inclined to the bias yarns
12
of the other sub-assembly and at ±45° to the warp feed direction. Transfer of the bias yarns
11
and
12
by the transfer mechanism
18
is fully described in WO94/16131.
The machine shown in
FIG. 2A
also includes a weft insertion station
23
for inserting the weft yarns
14
and
15
of the structure shown in
FIG. 1 and a
binding warp yarn insertion mechanism
25
which includes an insertion needle
24
which provides for the insertion of the binding warp yarns
13
of the structure
10
shown in FIG.
1
. It also includes a beater
30
.
The yarn transfer mechanism
18
in the machine illustrated in
FIG. 2A
under the control of drive mechanism
181
serves progressively to move the warp yarns of the warp sheet
17
into superposed diagonal ±45° non-woven warp yarn sub-assemblies as represented by the warp yarns
11
and
12
of the structure shown in FIG.
1
.
The yarn structure shown in
FIG. 1
is formed from the two non-woven inclined bias yarns
11
and
12
, the binding warp yarns
13
and the upper and lower weft yarns
14
and
15
in a succession of processing steps in a cycle of operation following each transfer step of the yarns
11
and
12
in the yarn transfer mechanism
18
. Following a bias yarn transfer step in the mechanism
18
a binding warp yarn insertion step is carried out in which binding warp yarn
13
is passed through the bias yarn structure behind the bias yarns
11
and
12
by the insertion needle
24
followed by a weft insertion step in which a lower weft yarn
15
is inserted at the weft insertion station
23
behind the binding warp yarn. This is followed by a beating up step using the beater
30
to bring the bias yarns
11
and
12
and the newly inserted lower weft yarn
15
to the fell point of the yarn structure being formed. The beater
30
is then retracted and the binding warp yarn needle
24
is returned to its retracted position following which a further weft yarn insertion step is carried out by insertion of an upper weft yarn
14
behind the return run of the binding warp yarn and is followed by a further beating up step. The beater
30
is then returned to its retracted position to complete the steps in a complete cycle of operation of the machine which is then repeated by the commencement of the next yarn transfer step carried out by the transfer mechanism
18
.
It will however be apparent that in the yarn transfer mechanism disclosed in WO94/16131 and hereinbefore described the yarns undergoing transfer in the forward and return transfer steps are required to move between the openings in the yarn guide member and the yarn transfer member many times in order to complete the succession of forward transfer steps followed by the succession of return transfer steps. As a consequence, it has been found that despite efforts to bring the gaps between opposing guide elements
26
and
28
to minimum tolerances, the warp yarns suffer abrasion when transferred from one member to the other and in some instances snag causing end breaks requiring shutdown of the machine of which the transfer mechanism forms part.
In International patent application No. PCT/GB95/01921 (publication No. WO96/06213) there is proposed a yarn transfer mechanism which does not require contact of the yarns with the guide elements in their transfer between the yarn guide member and the yarn transfer member. The transfer mechanism includes a plurality of eyelet elements through which the warp yarns of the warp sheet pass from a supply side of the mechanism to an opposite delivery side of the mechanism and which are supported by the guide elements for sliding movement along the elements into and out of the yarn guide and yarn transfer openings and with the yarn transfer member in any one of the registering positions for sliding movements from one opening in one member into a registering opening in the other member.
While the eyelet elements proposed for use in the yarn transfer mechanism disclosed in WO96/06213 solves the problem of excessive abrasion or snagging of the yarns when being transferred from one member to the other there is the disadvantage that use is limited to arrangements in which the eyelet size is not so small as to give rise to difficulties of manufacture and to operational and wear resistance problems.
It has however been found that weaving efficiency can be improved by incre

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