Braiding technology is attracting attention as a forming method for fiber-reinforced composite preforms. The square braider called the multi-braider can produce braiding preforms with various cross-sectional shapes. In the multi-braider, as the number of carriers increases and the carrier paths become more complex, it becomes more difficult to think about how to prevent carriers from colliding with each other. Therefore, the purpose of this paper is to develop simulation software for efficiently designing the carrier paths on the multi-braider when manufacturing a braiding preform with complex structure. We developed a simulator for the behavior of carriers when horn gears rotate continuously, using the carrier’s initial position and path or track as input values. The collisions can be identified in advance because the simulator indicates an error if the input values are not suitable. By introducing the carrier track simulation for the multi-braider, the work time to devise carrier paths and arrangements could be reduced to 1/3 for simple carrier paths and to less than 1/4 for complex carrier paths, making it possible to perform initial carrier placement efficiently. The results of this research will also improve the efficiency of design on the carrier’s initial placement and track and the safety of multi-braider operation.

During the production of synthetic fiber, a winder is used to wind the yarn, and the high-speed rotation of the package causes an increase in windage power due to high resistance from the surrounding air. However, to reduce costs of yarn production, it is important to improve energy consumption. Therefore, it is necessary to investigate the winder flow field using computational fluid dynamics（CFD）and reduce the windage power. In previous studies, simulations were performed using a model of the entire winder, however, the details on the flow field around the package were unknown. In this study, a touch-roll mechanism was incorporated into a simplified model to reduce the computational cost, and the flow field around the package was analyzed. The mechanism of increased windage was investigated to quantitatively determine the effective factors that reduce windage power by focusing on the flow field on the package surface layer that directly affects the windage. The results showed that incorporating the touch-roll mechanism had a significant effect on the windage power loss and the flow field, and that the increase in windage loss was observed particularly on the edge faces of the packages.