Orthogonal Analysis Of Drawing Defects In FDM 3D Printing Based On Vibration Signals

FDM printing technology as the most widely used technology in the manufacturing technology,the quality of its printing products has been hindering the further development of this technology,so that it can't be really popularized.However,almost all the FDM printers on the market have no quality monitoring system,which is an urgent problem to be solved in 3D printing.Therefore,in the process of FDM printing,it is very meaningful to establish a workpiece quality monitoring system to monitor the status of the workpiece in the printing process in real time.The main research contents of this thesis are as follows:(1)The structure of the 3D printer is designed and selected.through the analysis of the wire drawing of the printed workpiece monitored in this thesis three accelerometers are selected as the signal acquisition device.By analyzing the influence of the factors affecting the wire drawing of the workpiece in different positions of the printer,the installation positions of the three accelerometers are arranged reasonably.A vibration monitoring platform for FDM 3D printing workpiece wire drawing is built based on 3D printer,acceleration sensor,dynamic signal acquisition system and signal processing computer.The vibration signal of the workpiece during printing is collected by acceleration sensor and dynamic acquisition system to provide data support for later signal analysis.(2)The four parameters which affect the drawing condition of the printing workpiece,such as sprinkler temperature,pullback speed,retraction distance and idling speed,are introduced,and their role in the printing of the workpiece is explained.Through the time domain analysis of the wire drawing vibration signals of the printed workpiece collected by three sensors,the test evaluation index is determined.Based on four printing parameters,20 groups of single factor tests were designed and carried out,and the test results were analyzed with the corresponding test evaluation indexes characterizing the drawing condition of the workpiece.The results show that the four factors have influence on the wire drawing of the printed workpiece,and the experimental evaluation index can be used to characterize the wire drawing of the printed workpiece.(3)Through the orthogonal test,the influence of four factors on the wire drawing of the printed workpiece is further analyzed,and the test evaluation indexes of vibration signals under the three sensors are analyzed by range and variance analysis.It is known that the primary and secondary order of the factors affecting the wire drawing condition of the printed workpiece is as follows: retraction distance > nozzle temperature > retraction rate >idling speed.The best horizontal combination of factors is retraction distance 12 mm,nozzle temperature 190 C,pullback rate 50mm/s,idling speed 50mm/s.(4)The prediction model of the wire drawing condition of the printed workpiece is established by using the PSO-BP algorithm,and the four factors that affect the wire drawing of the printed workpiece are taken as the input of the model and the experimental evaluation index as the output of the model.The reliability of the prediction model is verified by the II group of Jiangsu University of Science and Technology.The results show that the prediction model established by using single factor test data as training samples is reliable.The reliability of the prediction model based on orthogonal test data as training samples is general.