1. Field of the Invention
The invention relates to a method for the production of non-fraying edges of a double woven fabric on a double-rapier loom, using a double-shed crossing device, said crossing device comprising per shed
a needle carrier with at least one elongated stationary needle, said stationary needle having two ends, one end of which, the fastening end, being fixed to said needle carrier, the other, free end being provided with a needle eye for the guidance of a stationary thread, said needle carrier being movable between a first end position and a second end position,
a slot plate with at least one oblique slot for the guidance of a crossing thread, said slot plate being movable between a first end position and a second end position,
a positioning device, in particular a perforated plate, with at least one eye for the positioning of said crossing thread in the respective oblique slot of said slot plate for the changeover of said crossing thread relative to an associated stationary thread by a corresponding shift of said positioning device relative to said slot plate, said positioning device being movable between a first end position and a second end position,
the method comprising the following steps:
weft insertion in the respective shed in a first shed positioning of said crossing device between said stationary threads and said crossing threads, said crossing threads being guided past said stationary needles between said free end and said fastening end thereof, said needle carrier being in its first end position and said slot plate being in its first end position, and
changeover of said respective crossing thread in relation to said stationary threads in the respective shed in a second shed positioning of said crossing device with said crossing threads running outside of the region of said stationary needles, said needle carrier, said slot plate and said positioning device being in their respective second end position.
2. Description of the Related Art
A double-shed crossing device to perform this method is known (DE-U No. 8005822; EP-B1 No. 0152956). In the case of these double-shed crossing devices, the needle carriers associated with the two sheds are fixed to a first main carrier and the slot plates are fixed to a second main carrier. Both main carriers carry out periodical lifting movements with a height of the lifting corresponding to the lifting of the shed with a phase shift relative to one another. At least in one of the two sheds the shift of the respective positioning device takes place at the change-over of the respective crossing thread while the shed is in its second shed positioning. The cross weave resulting in the upper woven fabric of the double woven fabric corresponds in its structure to the cross weave in the lower fabric, however, with an inevitable phase shift (of, for instance, one weft).
Double woven fabrics manufactured on double-rapier looms have in the case of double weft insertion the same weaving structure as a double woven fabric manufactured on a single-rapier loom (one pile loop per weft), only if warp threads are used which are guided in opposite directions. This weaving in opposite direction, however, requires double the amount of warp threads and correspondingly a jacquard loom with double capacity. In order to avoid this, that is to say to be able to operate with the single amount of warp threads, in case of a double-rapier loom, every second weft insertion can alternately be omitted in the upper shed and the lower shed.