Sand Mold Design Of Porous Structure And Texture Control Based On 3D Printing

In traditional sand cast,because the sand mold is dense,it is not easy to control the cooling of the casting well.Porous structure has the advantages of light weight,large surface area,high specific strength,shock absorption and energy absorption.With the development of 3D printing technology,there are a lot of research and applications in the manufacturing industry.The introduction of porous structure into non-dense sand mold for research can not only improve the production efficiency of sand mold,but also effectively control the cooling of casting,thus improving the casting performance.In this paper,the design of porous sand mold based on 3D printing and the control method of sand step texture were studied.In this paper,the classification design methods of periodic porous structures were summarized.Three types of 3D printing sand mold design were discussed,which are two-dimensional tensile structure,structure composed of rod elements,and structure of three-period minimal curved surface in periodic porous structure.Then the performance of periodic porous structure was preliminarily discussed by empirical formula and mathematical method,and the advantages of each structure type were listed.The static performance test and simulation of periodic porous structure were carried out.The tensile and compressive properties of honeycomb structure,cubic structure,octagonal truss structure,body-centered cubic structure and minimal G curved surface structure were tested by controlling the cross-sectional area and porosity,and the order of strength and weakness of each structure was obtained.In this paper,a sand mold with porous structure based on 3D printing is proposed,which is composed of shell mold with variable wall thickness,various sand mold porous structures(three period minimal curved surface temperature control structure,two-dimensional tensile bearing structure and lattice truss reinforcement structure)and temperature sensors.The temperature control structure is divided into temperature retaining structure and cooling channel structure.Through the closed loop of variable wall thickness shell mold,temperature control structure and temperature sensor,the state of the cooling medium in the cooling channel is adjusted during the cooling process of the casting to form the cooling control of the casting.At last,Pro CAST is used to simulate the porous sand mold casting of the casing,which verifies the feasibility of the porous sand mold to control the cooling of the casting.The 3D printing porous sand mold can improve the casting performance by controlling the cooling process of the casting.At the same time,it is also necessary to eliminate the step texture formed by the 3D printing sand mold that may affect the mechanical properties of the casting.In this paper,the effect of sand mold step texture on the static properties of castings was studied.The use of casting coating can eliminate the impact of the step effect of 3D printing sand mold,and has been verified by coating test.