Variable number of threads in braiding machines
A new embodiment of a braiding machine was developed at the Institute of Aircraft Design (IFB) of Stuttgart University. It features a thread positioning unit which forms a secondary ring of horn-gears close to the braiding point. This secondary ring moves synchronously with the primary horn-gears of the braiding machine. Therefore, the position of each thread, that is close to the mandrel, is clearly defined. This is a basic requirement for manipulation of specific threads during the braiding process, which in turn permits the automated production of components with highly varying diameters at a constant braid angle.
Braiding machinery serves a wide range of applications, including ropes, wire and cable designs and tubular products made of fiber-reinforced plastics. Manufacturers from different industries, in particular from the aerospace and automotive as well as mechanical engineering sectors, gradually use light-weight components to replace metal parts and components.
Presently, the number of threads in a braiding machine can only be changed manually and during machine downtime when using conventional braiding machines. However, for many parts and components it would be useful to vary the number of threads during the braiding process. Existing approaches are mostly based on parking of bobbins. In this case, however, the thread is not completely removed from the process.
The Institute of Aircraft Design (IFB) of Stuttgart University developed a new embodiment of a braiding machine with a thread positioning unit close to the braiding point.
The invention can also be implemented by embedding a positioning module into conventional radial or standard braiding machines. This positioning module forms a secondary ring of horn-gears which moves synchronously with the primary horn-gears of the braiding machine. The yarn is taken through to the machine center by this positioning module. Due to the synchronous horn-gear movements, the position of each thread, that is close to the mandrel, is clearly defined.
This is a basic requirement for having access to specific threads during the braiding process. Another module, either a separate module or a component of the positioning tool, could be used for thread manipulation, which acts precisely and selects specific threads. It cuts off single threads while keeping the thread tension or feeds them back into the braiding process in order to adjust the braid to a cross-section change in the axial direction. It would also be possible to vary the material properties of the final product by exchanging or coating individual threads during the braiding process.
Another advantage of the invention is that the use of a secondary set of horn-gears reduces the contact and friction between the 0°-yarns and braiding yarns. This contact leads to twisting of the 0°-yarns, which, in general, contributes to a wear of the fibers.
- Highly different ranges of component diameters at a constant braid angle
- Automated change in numbers and types of threads during the braiding process
- Minimizing twisting effects when using 0°-yarns
- As a retrofit kit or optional positioning module for radial and standard braiding machines
- Improved adaptability of the braid to complex geometries
Automated braiding process for components with highly varying diameters