Study On The Peek Pipe Fabricated By Continuous Gradual Bending And Stitching Process

In this paper,based on the PEEK pipe as the research object,a new type of continuous gradual bending and stitching pipe forming process was designed.Subsequently,the feasibility of the process and the main factors affecting the molding were verified by finite element method.The response surface method was used to optimize the cavity structure,and a prototyping test device was designed to meet the requirements of miniaturization and low energy consumption of in-orbit manufacturing equipment.Besides,the accuracy of simulation results and the rationality of equipment design were verified by molding process experiment,and the optimum molding process parameters were optimized.Aiming at the requirements of in-orbit manufacturing of truss tube units,the PEEK pipe continuous gradual bending and stitching pipe forming process was proposed.Through finite element method,displacement with the mod,stress analysis,suture welding and strain analysis were carried out to verify the feasibility of the process and explore the influence of strip thickness and forming temperature on the forming process.The results showed that the strip had good ability to follow the mold,the stress and strain distribution were uniform.Therefore,the continuous gradual bending and stitching pipe process of PEEK strip has high application value.The effect of the design parameters of continuous gradual bending cavity of PEEK strip on the longitudinal strain and feed reaction force was studied by finite element method.Aiming at improving the quality of pipe molding and reducing the feeding force,the mathematical models of the design parameters,longitudinal strain and feeding force were designed by Box-Behnken method.Then,on the basis of the induction mathematical model and genetic algorithm,the double-objective optimization of longitudinal strain and feed reaction was carried out to guide the design of the continuous gradual bending cavity of PEEK pipe.The results showed that the optimum design parameters of the molding pipe with thickness of 0.6mm were longitudinal amplitude of-10 mm,gap of 0.85 mm and inner surface length of 62 mm.Aiming at miniaturization of in-orbit manufacturing equipment,the molding device of the PEEK strip continuous gradual bending and stitching was developed.What’s more,the continuous gradual bending-stitching unit,feeding and traction unit,unwinding unit and shaping cooling unit of the molding device were designed in detail.A series of PEEK strip continuous gradual bending and stitching pipe molding process experiments were carried out to verify the accuracy of the finite element analysis result and the rationality of the equipment design,and to explore the influence of welding temperature and feeding speed on the surface quality,dimensional accuracy and weld strength of pipe.Moreover,the pipe quality evaluation method was established,and the optimum process parameters were analyzed and summarized.The results showed that the bearing property,surface quality and shape accuracy of the pipe were the highest when the forming temperature was 180～210℃,the welding temperature was 340℃,and the feeding speed was 1.5mm/s.The molding experiment of pipe with length of 800～1000mm was carried out,and the advantage of the design of process and molding device were revealed by analyzing the straightness of pipe.