Horngear and carrier design for braiding tailorable composite preforms

Abstract

Braids can be found in structural composite parts used in the car and the aerospace industries. The architecture of the braid has a direct impact on its mechanical properties. However, traditional braiding machines are limited to a single braid architecture. Few braiding machines, so called “3D braiding machines”, have been developed to enable variable carrier’s paths. This allows fabrication of several braid architectures using the same machine. These machines use a switching mechanism, which complexifies the machine and the braiding process. A new type of braiding machine was introduced in Assi et al. [1], which uses a “chain and sprocket” mechanism, allowing variable carrier’s paths without any switching mechanism. Nevertheless, the original chain and sprocket braiding machine cannot be used for vertical braiding. When placed in the vertical position, the carrier jam between the horngears due to the force of gravity. This limitation does not allow braiding over a mandrel or coupling the braiding machine with a pultrusion line. This paper presents design guidelines for enabling vertical braiding for the chain and sprocket braiding machine. A new carrier design is proposed as well as a new horngear design. Additionally, the carrier is fitted with a guiding foot and a track is machined into the braider’s bedplate. A functional prototype has been developed to validate the design. The design complexity has been assessed and compared to existing braiding machines. The design proposed in this paper remains 30% less complex compared to other vertical braiding machines enabling variable carrier’s paths.