Construction And Experimental Research Of Pneumatic Metal 3D Printing System

As the development of metal 3D printing manufacturing technology,it has produced a variety of mature and representative technologies,including selective laser sintering(SLS),selective laser melting(SLM),laser engineered net shaping(LENS)and three-dimensional welding technology,some of these technologies have gradually realized commercialization However,these commercial forming equipments still have many problems in terms of the range of materials used,the accuracy and efficiency of molding and the cost.In order to overcome these problems,this paper proposes a new type of metal 3D printing technology based on the principle of pneumatic metal melt extrusion deposition molding,and tries to set up the system and conduct an experimental research,aiming to reduce costs,increase the scope of use of the material and improve the accuracy and efficiency of molding of the components.This article describes the principle and characteristics of pneumatic extrusion deposition molding technology,and modeling the outflow process of metal liquid from nozzle in accordance with the nozzle model,we can conclude that the outflow based on the nozzle model can guarantee the uniformity and stability of the metal lines extruded,meanwile,we got the expression of the outflow flux,this provided theoretical guidance for follow-up experiments.On the other hand,we analysis the effects of parameters such as nozzle temperature,substrate temperature,driving air pressure and deposition speed on the outflow process and deposition molding process of metal liquid.The overall system was designed and constructed;Analyzed the functions of the various modules of the mechanical system,including the motion platform,spray head and substrate,and performed detailed structural design for them,solved key issues such as system motion,material extrusion and sealing;Described the control principle of the control system in detail,including the motion control system,air control system and temperature control system,and performed corresponding design and construction work,this solved problems such as precise movement control,precise pressure control and precise temperature controlAccording to the system built,Sn99.3Cu0.7 solder bar was used as the experimental material to study the influence of driving pressure and nozzle temperature on the outflow of metal liquid,and the influence of the substrate temperature,driving pressure,deposition speed and nozzle temperature to deposition of metal liquids was tested,got the best process parameters for obtaining the best line quality were:substrate temperature was 220?,deposition speed was 30mm/s,driving pressure was 0.08 MPa and nozzle temperature was 250°C.One-dimensional and planar forming experiments were carried out with optimized process parameters.The results verified the stability and uniformity in forming lines and the feasibility on molding plane of the system,and got the optimum trace spacing of the forming plane was 0.07mm.Finally,based on the quality defect of the forming surface in the plane experiment,an improved scheme was proposed for the system in order to improve the quality and accuracy of molding.