Research On Key Structure Design And Forming Process Of Metal 3D Printing Platform Based On FD

Metal 3D printing technology is widely used in equipment manufacturing,aerospace and other fields,and has been developing rapidly in recent years.The existing 3D printing technologies used to make metal parts mainly include selective laser melting(SLM),laser near net shape forming(LENS),electron beam selective melting(EBSM),etc.The above-mentioned 3D printing technologies for metals use high temperature(high temperature generated by electron beam or laser)to melt metal materials.There are shortcomings such as expensive equipment,high processing and manufacturing costs,and high requirements for metal material types.This topic aims to develop a low-cost metal 3D printing technology.To reduce the cost of printing equipment and printing materials.This topic focuses on designing a metal 3D printing platform combining screw extrusion technology and fused deposition modeling(FDM)technology and mainly study the FDM type screw extrusion metal 3D printing platform and its molding process.The research mainly includes the design of FDM metal 3D printing platform,the design of screw and fluid simulation analysis,the preparation of copper paste and printing process parameters research,the degreasing and sintering process research four parts.The main study contents and results are as follows:Carrying out the construction of FDM type screw extrusion metal 3D printing platform according to the principle of 3D printing.Specify the printing principle of FDM type screw extrusion metal 3D printer,and complete the structural design of the core component nozzle.The structure mainly includes screw extrusion device and feeding device.Completing the design of printhead control system.For a specific model of stepper motor,the driving schematic of the stepper motor driver is drawn,and then analysis of the nozzle stepper motor feeding extrusion command and the implementation of speed control are carried out.Using Arduino Uno board as the main controller,the control program of screw extrusion stepper motor and feed stepper motor is compiled and analyzed.Carrying out the design of screw extrusion device,the core component of FDM type screw extrusion metal 3D printing platform.Through the screw extrusion flow rate equation,the main influencing parameters that affect the screw extrusion flow rate are analyzed.Then ANSYS Fluent fluid simulation software was used to simulate and analyze the extrusion flow rate situation.That Determines the dimensional parameters of the screw(The effective length of the screw is 60 mm,the width of the screw groove is 6mm,the depth of the screw groove is 2mm,the lead of the screw is 8mm,etc).The optimized screw structure and parameters are simulated and analyzed.It mainly analyses the pressure field,velocity field and shear stress field of the screw.Conducting research on the preparation of copper paste and printing process parameters.The polyvinyl alcohol binder used in the experiments was made by mixing polyvinyl alcohol powder with deionized water,and the mass ratio was 1:9.It is verified through experiments that when the mass ratio of polyvinyl alcohol solution to cowder is 1:12,the nozzle is not easily clogged and the molopper pded part is not easily collapsed during the printing process,and the smooth extrusion of copper paste can be achieved.The effects of process parameters such as paste extrusion speed,printing speed,and print layer height on molding quality are investigated experimentally.The results show that when the slurry extrusion speed is 15.63mm/s,it is not easy to plug and the precision is high;When the printing speed is 15mm/s,the molding quality of the molded part is better;When the layer height is 0.24 mm,the connection between layers is tight without collapse.Carrying out research on degreasing and sintering process.The design of the degreasing process was guided by thermogravimetric analysis of the printed copper billets,and the best degreasing process was determined from experiments.Raise the temperature from room temperature to 260 ℃ at a heating rate of 5 ℃/min,and keep it at 260 ℃ for 30min;Then raise the temperature to 600 ℃ at the heating rate of 2 ℃/min,and then keep it for120min;Finally,it is cooled with the furnace.The degreasing rate reached95.9% after 352 minutes of degreasing.The optimal sintering process is determined based on macroscopic property testing and microscopic morphology analysis.Raise the temperature from room temperature to 1050 ℃ at a rate of 5 ℃/min,then keep it for 120 min,and finally cool with the furnace.The best mechanical properties of the molded parts were obtained,and the tensile strength of the molded parts was 93.48 MPa,the density was 7.649 g/cm3,and the hardness was 35.94 HB.