Assembly to lay bands of weft yarns between edge hooks and in different orientations has a rotating yarn layer with yarn guide openings set at angular alignments to give an adjustable laying width

摘要

The assembly to lay weft yarns, preferably in a multi-layer structure of multi-axial yarns, has a controlled yarn layer (30) to guide the wefts (20). It is moved together with rows of moving hooks on chains at the edges to hold the yarns in place and move the laid yarn layer(s) in a forward direction while retaining their orientation. In a laying cycle of the weft yarn band laying system, the yarn layer carries a number of wefts, to lay them at the moving edge hooks in at least two laying stages for different yarn orientations and at least two laying stages on the reverse movements. The width of the laid weft yarns is controlled at the side edges of the yarn layer(s) or outside the laying stages. The start position of the forward and backward layer laying stage is set according to an actual position of an oriented weft yarn band already laid in place, which is the actual growth position in relation to the hook chains. The advance movement of the hook carrier chains is controlled according to the duration of a yarn laying cycle. The hook carrier chains have a synchronized forward movement, according to the yarn laying cycle. The yarn laying cycle has a laying stage for the oriented yarns, a deflection stage around the edge hooks, and a return stage with a different yarn orientation. The gaps between the yarn guide openings (33) at the yarn layer are altered according to changes in the yarn laying orientation. Before adjustment, the yarn layer is rotated into a different angular alignment. The control sets the number of yarn laying stages at the edge hooks for different laying cycles and/or an advance of the laid and oriented wefts in each laying cycle, according to the advance movement of the hook chains on each laying cycle. The yarn laying movement extends as far as behind the needles of a side edge fixing system. After laying a band of wefts, the orientation is set by the yarn layer at an entry point for the next laying stage. A laying stage is extended after the side edge, by the length of a racking path, while the yarn layer is lowered. As the yarn layer is lowered, an edge fixing system grips the band of wefts from above to apply a grip to fix a section of the laid yarn band. The yarn layer and edge fixing system move on a swing path to the hook laying point of the next laying stage, and the yarn is transferred at the hook laying point. As the laid yarn is moved upwards in a curved yarn laying action around the hook laying point, the next laying stage starts to apply tension to the yarn. The fixing unit has a comb structure to grip the tensed yarns to give a new hook laying width between the fixing system and the yarn layer. The laid yarns can be tensed by lowering the yarn layer to a transfer comb, to tense the yarns at it by an angled rear movement and a following upwards movement and release them from the fixing system. An Independent claim is included for a system to lay bands of weft yarns at given orientations, by a controlled yarn layer which carries a number of weft yarns, to be caught at the edges by hooks on moving chains. Preferred Features: An additional yarn layer is used when laying more than three layers of weft yarns. The interval can be adjusted between the yarn guide openings at the layer, and the yarn guides (32,34) can be in a number of parts. The yarn layer has a slitted plate with diverging yarn channels, especially as slits. The plate can have a lateral sliding movement to set the yarn guide slits according to the width of the laid band of wefts. The yarn layer can be rotated to alter the gaps between the weft yarns. The yarn layer can have a grid bar with holes to guide the weft yarns, to be rotated into different angular alignments for a laying stage. The weft layer, to lay a number of weft yarn band layers, gives layers in mirror image alignments against each other.