Research Of Rapid Casting Process For Complex Geometric Components Using 3D Inkjet Printed Sand Molds

Traditional sand-casting processes for single-piece and small-batch complex geometric components often face challenges,including high mold costs,difficult shaping,extended production cycles,and low production efficiency.These bottlenecks have long troubled the manufacturing industry.However,the emerging 3D inkjet printing technology for sand mold rapid casting presents a promising alternative.Characterized by rapid,low-cost,and flexible manufacturing,this approach directly prints sand molds for casting without requiring molds,offering significant advantages and wide application prospects for the production of complex,customized components.In this study,sand molds were fabricated using 3D inkjet printing technology.The influence of three different base sands,inkjet printing process parameters,and heat treatment temperatures on the sand mold properties and dimensional accuracy were investigated.The casting process for complex geometric。0ng system was optimized,and the rapid casting production process for complex geometric components was validated in actual production.The manufactured castings were then characterized.The analysis of the impact of different base sands on sand mold properties revealed that the morphology and particle size of the base sands significantly affected the strength and dimensional accuracy of the sand molds.Microscopic ellipsoid-shaped sands from Shenyang Research Institute of Foundry resulted in higher mold strength and lower gas emissions.However,when compared to the sands from Germany’s Strobel and Anhui Dongyang,the printed sand molds exhibited pushing and pulling defects and more visible print lines,resulting in poorer dimensional accuracy.Considering the high price of Strobel’s quartz sand,this study adopted Dongyang Mining’s quartz sand for printing sand molds based on printing quality and manufacturing costs.The effects of sand thickness,pulse voltage and boric acid addition on the properties of sand mold were obtained.The results show that with the increase of sand thickness,the strength of sand mold first increases and then decreases,the gas and density decrease.When the sand thickness is 0.28 mm,the sand mold has the best dimensional accuracy.With the increase of pulse voltage,the strength,gas output and density of sand mold increase,and the dimensional accuracy of sand mold is better when the pulse voltage ranges from 90 V to 105 V.With the increase of boric acid addition,the strength of sand mold decreased,the density and gas output increased,but the dimensional accuracy did not change significantly.And according to the results,the printing scheme was developed under different printing conditions of single printing gray cast iron sand mold,single printing magnesium alloy sand mold,simultaneous printing gray cast iron sand mold and magnesium alloy sand mold.It effectively improves the flexibility of enterprises with gray cast iron sand mold and magnesium alloy sand mold in the process of production scheduling,and improves the space utilization rate of large 3D inkjet equipment platform.The effects of heat treatment temperatures at 60 ℃、120 ℃ and 180 ℃ on sand mold properties and dimensional accuracy of complex oil channel sand cores were investigated.The results show that the strength of sand mold increases when the heat treatment temperature is60 ℃,which is suitable for gray cast iron sand heat treatment.When the heat treatment temperature is 120 ℃,the gas output of sand mold decreases obviously,which is suitable for magnesium alloy sand heat treatment.For complex oil pipeline sand mold deformation at 120 ℃,it can be solved by adding support structures.The Pro Cast simulation software was used to compare and analyze the influence of bottom pouring scheme and middle pouring scheme on the casting properties.The results showed that the bottom pouring scheme was more stable in filling and smaller in shrinkage cavity and porosity.After optimizing the bottom casting scheme according to the simulation results,the volume of shrinkage cavity and porosity decreased from the original 2.73 cm~3 to 0.18 cm~3,and the maximum stress of the casting decreased from 260 MPa to 160 MPa.The maximum deformation of the casting decreases from 0.46 mm to 0.37 mm.In this pouring scheme,the preparation of gray cast iron was proportionally calculated,and the pouring samples and castings were tested.The test results showed that the surface quality,mechanical properties,metallographic structure and dimensional accuracy of the castings all met the requirements of the enterprise.In addition,X-ray detection was conducted on the casting A with shrinkage hole defects in the simulation results,and no hole defects were found in the casting.