Research On The Control System And Mixing Control Algorithm For Full Color 3D Printers

FDM 3D printing technology has undergone significant development in printing precision,speed,path algorithms,and material characteristics since the 1980 s.However,most 3D printers can only print a single color that is the same as the consumable material,and only a few can print multiple colors,limited to two-color mixing or random mixing of multiple colors,unable to accurately reproduce color information.Full-color FDM 3D printing technology can directly obtain the color appearance of product design without post-processing.Compared with traditional single-color 3D printed parts,full-color FDM 3D printers have significant advantages in the consumer industry,medicine,topographic model description,prototype models,and education industries.This study aims to develop a remote feed,intelligent mixing,and controllable fullcolor FDM 3D printer.Based on the analysis of the G-code data structure and data extraction method of 3D printing files,the triangle face color information is determined for 3MF files with model color information.By comparing the spatial coordinate point position information in the 3MF file with the coordinate points in the G-code,the color information is automatically added to the corresponding position in the G-code,which facilitates the printer to read the color information.In order to achieve accurate control of printing colors,on the basis of the principle of subtractive color in printing color theory,yellow,magenta,cyan,and white were selected as the four basic colors,and a mixing experiment platform was made.Through the platform,different colors of filaments were mixed in different proportions to extract the color information of the three primary colors after mixing,and the corresponding relationship between the filament ratio and the obtained RGB color was recorded as a sub-sample.A BP neural network model was established,and the 529 sub-samples obtained from the experiment were used to train the established BP neural network model.The corresponding relationship between the filament ratio and the RGB color after mixing was obtained,and the validity of the color matching BP neural network was verified through mixing experiments.The verification results show that the color error is small,indicating the reliability of the color matching BP neural network.On the basis of FDM 3D printing technology,a five-color mixing system was designed.The cooperative control system of the mixing system and the 3D printing system was developed,which synchronizes the mixing speed and 3D printing speed while ensuring the mixing quality.For the key problem in full-color printing-the handling of transition colors,the corresponding preset compensation algorithm was used.That is,based on the implementation of the color layer uniformity of the layered color change model,when printing the color change layer,the transition color is pre-printed in the filling layer through early monitoring with the real-time monitoring of the 3D printing process program,ensuring the purity of the appearance color.At the same time,in order to better print models with smaller cross-sections,the length of the transition color was measured experimentally on the basis of the mechanical structure of the mixing system,and the early opening of the mixing was carried out in actual control,so that the transition color would not affect the appearance color effect when printing smaller cross-sections.An experimental platform for a color 3D printer was built,and the corresponding mixing control system was developed.On the basis of the corresponding control algorithm research,a upper-computer control software system was developed using C#,which realized communication with the 3D printer,and also realized temperature control of the mixing system,mixing ratio control,and the cooperative control of the mixing system and 3D printing.For the layered color change model,the corresponding layered color change algorithm was written to achieve accurate color printing.