Mechanism Analysis And Experimental Study Of 3D Printing Technology On Blending Pure Copper Powder And Polymer

Pure copper materials were difficult to be widely used in the 3D printing industry due to their own high thermal conductivity and high reflection characteristics.At present,laser sintering was mostly used to print copper alloys on the market,and there was no more mature printing method for pure copper materials.In response to this problem,this paper proposes a convenient and efficient low-cost pure copper 3D printing method—pure copper powder-polymer composite blending 3D printing technology.The key to this technology was to prepare a blend of pure copper/ceramic powder and polymer composite materials,and used a particle-feeding dual-nozzle printer to print pure copper blanks.The main nozzle prints pure copper material and the auxiliary nozzle prints ceramic support materials.Put the printed body into a high-temperature and high-pressure heat treatment sintering furnace for sintering,remove the support,and prepare high-quality pure copper special-shaped parts.The main tasks completed in this paper are as follows:(1)Research on the mixing mechanism of copper powder and polymer composite materials,detailed analysis of mixing methods,selection criteria of mixing materials and testing methods of mixing uniformity;analysis of materials inside the printer Using rheological formulas,several main factors affecting the fluidity of the mixture are analyzed,and a mathematical parameter a_STV that can evaluate the overall rheological properties of the material is obtained.The larger the value,the better the rheological properties of the material;the dewaxing and sintering mechanism of the pure copper-polymer composite blend 3D printed body is studied,and the microstructure changes in the body during the dewaxing and sintering process are studied until the product is formed.(2)A particle-feeding dual-nozzle printer that can use pure copper powder-polymer composite materials was developed,and the melt conveying printer head,printing platform,temperature control system and signal control system were designed and selected.(3)Use ANSYS software to analyze the heat conduction of the material conveying device and the material extruding device in the dual-nozzle printer,and obtain the temperature distribution of the material conveying sleeve and runner adapter block of the main nozzle and the auxiliary nozzle to guide the printing process temperature Settings.(4)Through the analysis of mechanism and simulation results,formulate experimental plans,and respectively determine the best formula of pure copper powder-polymer composite material,the best printing parameters of the particle-feeding dual-nozzle printer,and the best dewaxing and sintering of pure copper blanks.The best technology and pure copper/ceramic powder-polymer composite materials are studied with the same shrinkage experiment.The research results are as follows:a.The mass fraction of pure copper powder is 91.34%,which is the best formula for the mixture.b.The best process for printing pure copper blanks is:screw temperature 180°C,melt pump speed 6r·min^-1,extrusion temperature 175°C,hot bed temperature 55°C.c.When the highest sintering temperature is 1040?,the pure copper product obtained has the best performance(the hardness requirement is below 62.6HV),and its various properties are:product density 7.44 g.cm^-3,Rockwell hardness 62.6HV,tensile strength The strength is 222.4Mpa,and the yield strength is 52.2 Mpa.d.The size of the sample after sintering is compared with the size before sintering,and the shrinkage ratio of the product is obtained:the shrinkage coefficient in the horizontal direction is 0.7664,and the shrinkage coefficient in the vertical direction is0.76007.The model needs to be enlarged 1.3048 times and 1.3157 times in the horizontal and vertical directions before printing.e.Research on the same shrinkage rate of ceramic/pure copper powder-polymer composite material:When the ceramic content of the ceramic support material is90.80%,the shrinkage rate is basically the same as that of the pure copper main material.f.Verification of printing and sintering of special-shaped copper parts:the prepared pure copper/ceramic powder polymer composite was printed by particle feeding double nozzle printer and dewaxing and sintering to remove support,and the pure copper special-shaped parts with good performance were prepared,which verified the feasibility of the whole test scheme.