DIRECTIONAL DEPENDENT YARN TENSIONING REGULATIONFOR THE PRODUCTION OF MULTI-AXIAL REINFORCEMENTSTRUCTURES

摘要

The modern warp-knitting technology allows for the manufacture of multi-directionalwarp-knits with a defined property profile. Particularly with regard to the manufacturing of open facedreinforcement structures the quality of orientation and yarn distribution within a yarn layer has to beoptimised up to the finished product. Based on existing textile-technological requirements regardingthe multi-axial insertion of yarns during the presentation new engineered solutions for a optimisedinsertion process will be introduced. The perpetuation of the modelled structural geometry as well asthe gently adjustment of uniform yarn tension for all inserted yarn layers are the main focus of processoptimisation.In contrast to tight packed yarn layers, which are relatively insensible against variations in yarn tensionduring manufacturing, the quality of open faced warp knit structures is greatly influenced by thenon-uniform yarn tension. Insufficient yarn tension regulation during the manufacturing process leadsto deviation of single yarn layers regarding their insertion angle as well as to arcs within the yarnlayer. Especially, the different yarn distribution within the yarn layer in different directions is difficult.A varying yarn tension resulting from different distinctive deformations of the insertion and transportationsystem can be avoided by increasing the stiffness of the transportation unit and improving thebearing with concurrent adjustment of the yarn tension.The developed process engineered and constructed solution refers first to the manufacturing process ofwarp knits on a warp knitting machine. The presented solution is valid independently from the yarnfixation.