| Resin is a kind of polymer in all raw materials of plastic products.It is the main component of plastics and has a wide range of uses.Compared with other manufacturing processes,3D printing technology has more excellent manufacturing capability for complex shapes,which facilitates the rapid development of various personalized plastic products with complex shapes.FDM-3D printing of heat-resistant resins requires much more heat than that of ordinary resins,which makes it difficult to design the print equipment,printing process and forming control.At present,most FDM printers on the market can not form heat-resistant resins,few researches have been done on the machine and the design of print head suitable for FDM-3D printing heat-resistant resins.Besides,there is some insufficient information on the process parameters and the properties of molding parts by FDM.In this project,our work on the FDM-3D printer of heat-resistant resin and research on its preparation process and material properties has been carried out.The equipment suitable for FDM-3D printing heat-resistant resin was successfully developed.Two representative heat-resistant resins,PEEK and PEI,were selected to optimize their printing process.Finally the printing samples with high mechanical properties were obtained.The following work has been carried out in this project.The mechanical and control system of traditional FDM equipment on the market were analyzed firstly.The design requirements of FDM-3D printer for heat-resistant resins were put forward based on the physical and chemical characteristics of heat-resistant resin.Then the structure of printing head,extrusion mechanism,transmission mode and the body structure of printer were improved and designed according to the requirements.Virtual assembly research was also carried out.Aiming at selection of the software and hardware of FDM equipment,according to the mechanical system and the design requirement,the firmware parameters were allocated and the independent temperature control system of printing floor was designed.The software and hardware adapting of the control system f'or FDM-3D printing heat-resistant resin has been completed.Finally the FDM-3D printer for heat-resistant resin was built and some complex structure parts were printed.In order to improve the efficiency and progress of preparation technology research.combined with the functional characteristics of FDM-3D printing,the finite element simulation of some key parameters was implemented.Firstly,the viscous constitutive models of PEEK and PEI were established.Secondly,the effects of different heating temperatures and wire feeding speeds on temperature field,viscosity field and pressure field distribution in nozzle runner were studied.Thirdly,the fluidity and melting situation in nozzle runner were analyzed.Finally,the nozzle structure and printing parameters suitable were obtained based on the above simulation results.The FDM-3D printing formability and performance of PEEK and PEI were further studied.The key process parameters affecting heat-resistant resin printing,printing temperature and direction,were selected to study their effects on properties such as relative density,flexural strength,tensile strength,fracture elongation and impact strength.The highest relative density,flexural strength,tensile strength and fracture elongation are 92.8%.135 MPa.84 MPa,16.7%for printed PEEK and 89.9%,123 MPa.79 MPa and 4.5%for printed PEI.Respectively,the failure phenomena and mechanism of PEEK and PEI were studied.The bending process of PEEK was characterized by a plastic process,there was necking pheno,menon in its tensile process and mixed characteristics of ductile fracture and brittle fracture in its impact process.While the bending,tensile and impact processes of PEI were characterized by brittle fracture. |
PDF Full Text Request