3D printing process for textile composites

The geometry of a braid influences its mechanical properties directly. On the other hand, the path of the carriers dictates the geometry of the braid. In traditional braiding machines, the carriers move along a fixed path, via horngears, which cannot be changed during the braiding process. This limitation does not allow braiding with variable geometry parameters along its axis, such as variable thickness and variable cross-sections. This paper presents a braiding machine design allowing a completely independent carrier movement. This process is analogous to 3D printing where layer-by-layer deposition produces a final part. In our case, controlling the position of each intertwining yarn will create a 3D braid. Each carrier can move without affecting the position of its neighbors allowing an easier and total control on the position and morphology of each intertwining yarn. A novel horngear design is proposed. The horngears are independently driven. They occupy the bedplate area in a hexagonal compact arrangement. The carrier path can be divided into multiple pre-defined unitary displacements. Driven by the horngears, the carrier follows these successive unitary displacements. A prototype of the braiding machine has been developed and tested with three independent carriers. As a first step, a flat braid with three yarns is produced. In the second step, a braid with a variable cross section is produced: a flat braid turning into yarn twisting. This proof of concept opens-up the possibility of 3D-printing textile composites with tailorable mechanical properties. (C) 2021 CIRP.