Research On Prefabricated Suture Head Of Rigid Foam Sandwich Structure With Pre-stab Function

The foam sandwich structure preform is a special form of composite material,which is composed of a core layer and two surface layers.By combining different core materials and surface layer materials,the characteristics of each layer are used to achieve different functions.The rigid foam sandwich structure preform has excellent characteristics such as high strength,light weight,sound insulation and heat insulation,and is currently mainly used in aerospace,shipbuilding and construction fields.In order to realize the automatic stitching of rigid foam sandwich structure preforms,this article is based on the research status of domestic and foreign preform stitching molding equipment,and researches on the stitching technology of rigid foam sandwich structure preforms with pre-stabbing function.The main research contents are as follows:To study the stitch forming principle of the Tufting stitching process,aiming at the phenomenon that the carbon fiber of the stitching thread breaks when the rigid foam sandwich structure preform is stitched by the Tufting process,the Tufting stitching process is improved,and the stitch forming steps of the improved Tufting stitching process Each mechanism of the suture head is designed and compared to determine the final plan for pre-needling mechanism,suture mechanism,needle changing mechanism and presser foot mechanism.According to the requirements of the improved Tufting suture process,it is determined that the pre-needle mechanism and the suture mechanism use the offset crank slider mechanism.The mechanism is first solved by the analytical method,and then the mechanism parameters are optimized based on ADAMS to determine the relevant parameters of the mechanism;to ensure the needle changing mechanism To meet the requirements of unlimited service life,establish and analyze the impact model of the needle changing mechanism;finally complete the static failure analysis of the presser foot mechanism to ensure that the design of each mechanism is safe and reliable,and establish a three-dimensional model of the suture head.The stitch forming technology of the stitching head when stitching the preform is studied.First,the mechanical behavior of the machine needle is analyzed.The needle diameter range is calculated by the inverse method,and the needle diameter used is determined.The machine is measured based on the finite element simulation software.Analyze the static failure of the needle;secondly,analyze the shape of the suture thread loop during the stitching process of the machine needle;establish the thread loop molding model of the elastic rod to determine the needle withdrawal height;finally establish the tension model when the suture thread passes through the thread channel,and Perform tension simulation analysis to determine the compression of the truncated cone spring when the stitching quality is good.In order to verify the effectiveness of the pre-needling function,the correctness of the thread loop theory and the feasibility of improving the Tufting suture process,the experimental platform of the suture head prototype was completed.The results show that the increased pre-needling action effectively reduces the probability of yarn breakage when the carbon fiber is used as a suture thread and the rigid foam sandwich structure preform is sutured;when the needle withdrawal height is 10 mm,the loop forming is stable and the suture can be continued.