Abstract
Braids are generally divided into 2D braids and 3D braids. Two-dimensional braids include flat braids and circular braids. Circular braids represent three-dimensional textiles, as they enclose a volume, but consist of a two-dimensional yarn architecture. Three-dimensional braids are defined by a three-dimensional yarn architecture. Historically, 3D braids were produced on row and column braiding machines with Cartesian or radial machine beds, by bobbin movements around inlay yarns. Three-dimensional rotary braiding machines allow a more flexible braiding process, as the bobbins are moved via individually controlled horn gears and switches. Both braiding machines at the Institut für Textiltechnik (ITA) of RWTH Aachen University, Germany, are based on the principal of 3D rotary machines. The fully digitized 3D braiding machine with an Industry 4.0 standard enables the near-net-shape production of three-dimensionally braided textile preforms for lightweight applications. The preforms can be specifically reinforced in all three spatial directions according to the application. Complex 3D structures can be produced in just one process step due to the high degree of design freedom. The 3D hexagonal braiding technology is used in the field of medical textiles. The special shape of the horn gears and their hexagonal arrangement provides the densest packing of the bobbins on the machine bed. In addition, the lace braiding mechanism allows two bobbins to occupy the position between two horn gears, maximizing the number of bobbins. One of the main applications is the near-net-shape production of tubular structures, such as complex stent structures. Three-dimensional braiding offers many advantages compared to 2D braiding, e.g., production of complex three-dimensional geometries in one process step, connection of braided layers, production of cross-section changes and ramifications, and local reinforcement of technical textiles without additional process steps. In the following review, the latest developments in 3D braiding, the machine development of 3D braiding machines, as well as software and simulation developments are presented. In addition, various applications in the fields of lightweight construction and medical textiles are introduced.
Highlights
IntroductionThese braiding machines are characterized by the intertwining of the processed yarns in all three spatial directions; on the other hand, they are still limited with regard to the direction of the bobbin’s movement on the machine bed
For the development of more complex braided structures, the technology of braiding has evolved over the years, so that the fields of application have progressed from the aforementioned simple, flat and round braids to three-dimensional structural geometries using 3D braiding technologies
In order to produce three-dimensional braids, circular braiding machines have been modified for the overbraiding of a tubular core
Summary
These braiding machines are characterized by the intertwining of the processed yarns in all three spatial directions; on the other hand, they are still limited with regard to the direction of the bobbin’s movement on the machine bed Due to this limitation, the complexity of the 3D geometry produced with Cartesian braiding machines is limited. To increase the complexity of the geometry, 3D rotary braiding machines were developed, where the bobbins’ movements are controlled individually via horn gears and flexible switches Due to these developments in the machine technology for 3D braids, the fields of application have progressed from the aforementioned simple, flat and round braids to technical applications, where three-dimensional structural geometries are required.
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