| Three-dimensional(3D)braided composites have the space interweaving structure,which overcomes the shortcomings of traditional laminated composites that they are easy to be delaminated.They also have higher energy absorption and good impact resistance except the characteristics of traditional composites.As we know,the development of 3D braided composites relies on advanced braiding equipment.Compared with foreign countries,our country’s 3D braiding equipment have low automation,single process and narrow application range.Therefore,it is of great significance to carry out researches on 3D braiding equipment and its braiding process to improve the level of integrated design and manufacture of braided preforms.Aiming at the advanced 3D rotary braiding machine at present,this thesis carries out modular design on its framework to get the universality and expansibility,then analyzes and designs each module,and ultimately obtains a kind of 3D rotary braiding machine with scalable scale and strong trajectory changing ability.According to the arrangement of the moving parts on the braiding machine,mathematical representations of them are given,then the algorithm to calculate carrier path is established.By analyzing the influence of switches on braiding trajectory,process methods to fabricate typical braided structures on this braiding machine are obtained.Based on the relationship between carrier path and the fabric structure,yarn fitting curves are obtained by fitting the yarn spatial characteristic points with quadratic B-spline curve.The visual model of braided preform is built.A process simulation interface is developed to generate the fabric structure under arbitrary process parameters.In order to automatically control the braiding machine,corresponding numerical control system is designed according to its mechanism and technical requirements.In order to increase and decrease the number of control axes conveniently,the "PC + CAN Bus + MCU" scheme is adopted and the hardware and software are designed accordingly.The prototype of 3D rotary braiding machine and its control cabinet are built and debugged.Experiments are carried out to verify the analyses on the structure scheme,process method and fabric model. |
