Development Of Plunger-Screw Extrusion Large-format Paste 3D Printing Equipment

Sculpture is an important carrier of urban cultural construction.With the continuous acceleration of urbanization,a large number of personalized urban sculptures are needed to build public cultural spaces.At present,the production of urban sculptures is mainly manual,and there are problems such as cumbersome production process,long production cycle and high cost,which are far from meeting the needs of the market.With the development of 3D printing technology,it is gradually possible to use 3D printing technology to make urban sculptures to simplify the production process and reduce costs.This research focuses on developing a plunger-screw extrusion large-format paste 3D printing device that can be used to make urban sculptures.The main research contents are as follows:(1)The factors affecting the structure design are discussed,and the gantry kinematic structure and linear transmission mode are compared and analyzed.Then,based on the results of the comparative analysis,the design scheme of the motion and control system is proposed,and the motion and control system of the large-format 3D printing equipment is specifically designed and built.(2)The factors affecting the design of the slurry extrusion system are analyzed.By comparing the characteristics of the four extrusion system combinations,it is found that the advantages of the mechanical plunger+screw extruder combination are obvious.The extrusion system composed of mechanical plunger and screw extruder is designed in detail,and the optimum motor speed ratio of mechanical plunger and screw extruder is determined.At the same time,a vibration-assisted printing module suitable for installation near the nozzle of the screw extruder was designed to improve the extrusion quality.(3)By printing a model with discontinuous paths,the control effect of the designed screw extruder on the flow rate is verified.The verification results show that the designed screw extruder can precisely control the extrusion flow.At the same time,by experimenting nozzles with different inclination angles,it is found that the shape quality and inclination angle of the nozzles also have a significant impact on the extrusion effect and printing quality.The effect of applied vibration(frequency 25Hz,vibration speed 15～16mm/s,vibration amplitude 0.2～0.3mm,vibration acceleration12～13.5m/s~2)on the printing quality of the sample was studied.The results of vibration experiments show that:when printing complex samples with filling inside,applying vibration can effectively reduce the defects on the surface of the samples at higher printing rates and significantly improve the surface quality.When printing thin-walled samples consisting only of the outer contour,the application of vibration may cause negative effects such as deformation and instability due to the lack of padding that acts as a stable support.The research results have practical significance for improving the quality and yield of sculpture printing products and promoting slurry 3D printing technology.