Research On High Efficiency Wood Plastic 3D Printer System Design And Temperature Control

With the development of China's science and technology,3D printing technology has entered a period of rapid development.3D printing has been given the background of the "third industrial revolution".The rapid prototyping technology represented by 3D printing technology is regarded as A key element that triggered a new round of industrial revolution.As the most widely used FDM printing technology in the market,it has not been able to break through the limitations of using standard size wire materials,which limits processing efficiency and processing materials.Based on the defect of FDM technology,this paper develops a wood-plastic 3D printer with STM32 microcontroller as the control core based on the existing single-screw extrusion technology.The main research contents of this paper include mechanical structure design,hardware design and program design of wood-plastic 3D printer.According to the technology of single-screw extruder and 3D printer 3D motion platform,the overall structure of wood-plastic 3D printer is carried out.Firstly,a small screw with equal isometric depth is designed as the feeding extrusion device.According to the design of the screw,a reasonable power device and heating device are selected.According to the structure of the screw extrusion device,a three-dimensional motion platform is designed,and the experimental prototype is built according to the three-dimensional modeling.According to the structural function requirements of wood-plastic 3D printer,the modular hardware circuit with STM32 single-chip microcomputer as the control core is designed.The module hardware circuit includes main controller module,stepping motor drive module,temperature control module and human and interaction module.The main control module sends data through the serial port to control each module to complete the printing work.Designed for the wood-plastic 3D printing software program,including main program design,stepper motor motion control program design,and temperature control program design.The adaptive acceleration and deceleration control method of PID is adopted for the stepping motor motion control program.For temperature control,this paper uses a single neuron PID algorithm to optimize temperature control accuracy.The theoretical study on the temperature flow field of wood-plastic granular material melt-extruded in the screw was carried out to study the heat transfer mode and thermal boundary conditions of the wood-plastic particles during the screw extrusion process.Establish flow equations and constitutive equations for wood-plastic particulate materials.The numerical simulation of the temperature field of the extrusion nozzle was carried out under the rated speed of the screw using Fluent software,and the temperature heating range of the wood-plastic 3D printer under normal working was obtained.According to the simulation results,the orthogonal experimental model with nozzle temperature,screw speed,nozzle diameter and feed speed and printing speed ratio was designed.The wood-plastic 3D printer designed in this paper was used to print 16×5 sets of workpieces,and the test specimens were printed.The mechanical properties were obtained by four factors affecting the strength of the printed test piece:temperature>feed rate>ratio of print speed to feed rate>nozzle diameter,and analysis of the effect of heating temperature and feed rate on print strength.Finally,the optimal process parameters of the wood-plastic 3D printer are obtained.