Optimization Design Of Multifunctional Placement Head For Laser In-situ Forming Of Resin Matrix Composites

Continuous carbon fiber reinforced composites have a series of advantages such as high fatigue strength,strong machinability,and reusability,which have become the focus of attention in the fields of aerospace,transportation,and petroleum and wind power.Laser in situ molding is an ideal molding method for continuous carbon fiber reinforced thermoplastic composites.The placement head is an indispensable key component in the molding equipment,and its function,performance,and quality determine the molding effect and component quality.Aiming at a series of issues such as controlling the uniformity of the heating temperature field during laser in situ molding,rapid self tuning and stability control of the heating temperature,pressure stability control,and interference with the mandrel axis,the paper mainly focuses on the optimal design of the laser placement head.The research results will have important engineering guiding significance for promoting the development of laser in situ molding technology for continuous carbon fiber reinforced composites.On the basis of investigating the current research status of temperature control technology for continuous carbon fiber reinforced composites in situ laser molding at home and abroad,the paper introduces the characteristics of continuous carbon fiber reinforced thermoplastic composites and the basic principles of laser in situ molding.The optimal design of the placement head is described from several aspects,such as the distribution of the heated spot light field,the stability control of placement pressure,temperature stability control and rapid self tuning,optical mechanical structure,and placement path planning.The paper mainly introduces the following research work:In order to solve the problem of nonuniformity in the direct heating temperature field caused by the nonuniformity in the light field distribution of a single/multimode laser beam,from the perspective of optimizing the light field distribution of the heating spot,a square light spot with uniform light field distribution was obtained by combining a random phase zone plate array and a positive lens on the focal plane.Under the irradiation and heating of the square light spot,a uniformly distributed square temperature field was obtained;Aiming at the instability of pneumatic pressure caused by the instability of composite prepreg tape,a stable placement pressure was obtained by using hydraulic pressure method from the perspective of placement pressure stability control;Aiming at the problem of temperature stability control and rapid self-tuning for laser in situ molding,a temperature closed-loop control system based on an intelligent fuzzy PID controller is introduced.Starting from the basic principle of the temperature intelligent fuzzy PID controller,a fuzzy self-tuning PID control algorithm is introduced,and the temperature control program and fuzzy control rules are compiled.The fuzzy self-tuning PID control algorithm is introduced into the PLC to obtain the temperature output response from the upper computer.The results show that when using an intelligent fuzzy PID controller,the temperature control accuracy is maintained at ±10 ℃,the overshoot is about 2.29%,and the adjustment time is about 9.7 seconds.All indicators meet the conditions,with good dynamic response and steady-state characteristics,good temperature tuning effect,and high degree of fitting;Aiming at the problem that the placement head is prone to interfere with the core mold axis during laser in situ molding,the optimal design is carried out from two perspectives: the optical mechanical structure of the placement head and the placement path planning.In order to verify the rationality of the design of the multifunctional placement head,a model of the rotary core mold was designed in the paper.Based on this model,the placement trajectory of the prepreg tape was programmed and simulated,and a placement experiment was conducted in a real environment.By observing and comparing the actual and simulated motion trajectory of the placement head driving the pressure roller on the core mold,it can be concluded that the actual motion trajectory is basically consistent with the simulated motion trajectory,both can move according to the expected trajectory planning,with good molding quality and no interference.The placement head designed in the paper integrates multiple functions such as laser heating,temperature measurement,and pressurization.It has the advantages of light weight,small volume,rich functionality,and high temperature control accuracy.It not only improves the placement efficiency and accuracy,but also improves the issue of interference between the laying head and the core mold axis.