Abstract:

Objective Hexagonal three-dimensional braiding technology enables more flexible braiding processes, allowing for the fabrication of complex braided structures. The flexibility resulted in challenges such as difficulty in process development and lack of systemization, failing to meet the demands of hexagonal braiding technology. Therefore, a hexagonal braiding technique was proposed for tubular fabric structural design aiming to address these issues. By establishing an inherent connection between fabric structure and braiding machine through equivalent horn gears, the efficiency of hexagonal three-dimensional braiding technology design for tubular fabrics was enhanced.

Method Initially, the transfer principle of the yarn carrier on the horn gears was analyzed, and the theory of equivalent horn gears was proposed. Combined with the structure and motion characteristics of the hexagonal braiding machine, the equivalent horn gears unit of the braiding machine was proposed. Subsequently, based on the structural parameters of tubular fabrics, the inherent connection between the arrangement law of the yarn carrier and the fabric structure was established based on the equivalent horn gears. Finally, by analyzing the yarn forming process, the bottom plate process unit was defined. Combining with the principle of tubular fabric forming, the bottom plate structure of the hexagonal braiding machine equivalent horn gears system was constructed, obtaining the arrangement law of the yarn carrier, elucidating the movement criteria of the yarn carrier, and obtaining recyclable process steps.

Results Firstly, the principle of carrier position transformation was analyzed, and the theory of equivalent horn gears was proposed. Combined with the structural characteristics of the second-generation hexagonal braiding machine, the equivalent horn gears unit of the second-generation hexagonal braiding machine was proposed, further elucidating the chassis motion unit of the hexagonal braiding machine equivalent horn gears system. Secondly, based on the structural parameters of tubular fabrics, and the structural characteristics of the equivalent horn gears, the inherent connection between the arrangement law of the yarn carrier and the fabric structure was established, reflecting the forming principle of tubular fabrics. Thirdly, by analyzing the fabric forming principle, the bottom plate process unit was defined. Then, combining with the principle of tubular fabric forming, the selection principle of the equivalent horn gears unit was proposed, and the bottom plate structure of the hexagonal braiding machine equivalent horn gears system was constructed, thereby determining the arrangement law of the yarn carrier. Fourthly, the yarn carriers were arranged based on the interweaving centerline, and the motion steps of the process units were planned respectively, resulting in recyclable execution steps. Fifthly, the braiding process of the 3∶3-1 tubular fabric was designed, and relevant experiments were conducted, achieving consistent fabric structural characteristics with the designed fabric configuration.

Conclusion Building upon the foundation of hexagonal horn gears and stepwise directional motion and drawing inspiration from the establishment method of Maypole tubular fabric forming process, this study explores the hexagonal three-dimensional braiding technology for tubular fabrics. Leveraging the structural characteristics of the second-generation hexagonal braiding machine, the theory of equivalent horn gears is proposed. Mapping the arrangement of yarn carriers to fabric structure, a hexagonal braiding technology based on the theory of equivalent horn gears is developed. Finally, the feasibility and correctness of this approach are verified through braiding experiments. Although hexagonal three-dimensional braiding machines have been continuously improved in mechanical and electronic control aspects, enabling more flexible braiding of complex fabric structures, a corresponding universal braiding technology or theory for hexagonal braiding has yet to emerge. Systematic methods still lack to establish the regulatory relationship between braiding processes and fabric structures. The hexagonal braiding technology proposed provides effective technical support for the rapid development of tubular fabrics, filling the gap in the braiding process system of hexagonal braiding machines and promoting the advancement of hexagonal braiding technology. With the popularity of hexagonal braiding machines, new production demands continue to emerge, driving the development of hexagonal braiding technology to new heights.

Key words: hexagonal braiding, tubular braid, braiding technology, equivalent horn gear, yarn carrier, composite material