Research On Robotic Placement Machine And Placement Process Of Thermoplastic Composite

Compared with thermosetting composites,thermoplastic composites have many outstanding advantages,such as simple forming process,weldability,easy recovery and low manufacturing cost.As a result,they have broad application prospects in aviation,transportation,sports and other fields.Through nearly 30 years of exploration,the research of thermoplastic composite placement technology abroad has been more in-depth,and many research institutions and enterprises have developed high-performance placement equipment.In order to follow up foreign research in this field and improve the manufacturing level of aeronautical composite components in China,it is necessary to develop thermoplastic composite placement equipment and related processes with independent intellectual property rights.Firstly,aiming at "in-situ curing" of thermoplastic composites,this thesis designs a placement head for thermoplastic unidirectional preprepreg tape,which includes six mechanisms: tension control,clamping,refeeding,cutting,heating and pressing.The shortest placing distance of the finished placement head is 132.07 mm,which can be used to lay GF/PP,CF/PEEK and other thermoplastic composites.Secondly,the finite state machine model of the placement process is established,and the coordinated control between the placement head and the robot is realized by the control method of state switching.The placing speed is calculated using the development interface of the robot,and the following control of the refeeding motor is realized,which solves the problem of refeeding with a variable placing speed.The closed-loop control of tension is realized with the feedback displacement of jump roller using the differential advance PID algorithm.The test results show that the refeeding error and the cutting error of the equipment are ±1.5mm and ±0.1mm respectively.Then,three factors and three levels of orthogonal experiments were designed by choosing heating temperature,laying speed and combining pressure as experimental factors.Nine groups of GF/PP laminate specimens were laid with robot placing equipment,and the comparative specimens were prepared by vacuum bag assisted forming process.Finally,the microscopic observation of the samples prepared by different processes was carried out,and the microscopic explanation of the difference in appearance between the samples prepared by the placing process and the vacuum bag assisted forming process was obtained.The test results of bending strength were analyzed by range analysis and response surface method.The function relationship between heating temperature,laying speed and bending strength was established,and the optimum process parameters were obtained.The experimental results show that the bending strength of the specimens laid with optimized process parameters reaches 95.12% of the vacuum bag assisted forming process,and the surface quality is good.