多材料砂型增材制造层间加热与压实整体成形工艺研究

目的 针对砂型打印过程中存在层间结合力差和树脂含量与发气量难以协调等问题，提出多材料砂型增材制造层间加热与压实整体成形工艺，实现多材料砂型的高性能制造。方法 基于多材料砂型加热压实一体化成形装置，通过优化匹配辊轮旋转速度、辊轮直径和加热温度等加热压实一体化成形工艺参数，实现对砂型力学性能的精确调控，并通过铸造试验进行应用验证。结果 通过自旋辊轮压实的方式辅助铺砂，当辊轮直径为60 mm、辊轮转速为3 r/s时，铺砂效果最好，砂型强度最高，砂型透气性满足铸造需求;针对1.5 mm厚度的具有片层堆叠结构的复合砂型，优选出层间加热压实一体化成形工艺参数如下:层间加热温度为150 ℃，辊轮直径为60 mm，辊轮转速为2 r/s。验证了采用层间加热压实一体化成形工艺可制备高质量的多材料复合砂型，砂型与铸件均具有良好的尺寸精度和性能，1.5 mm片层堆叠结构的复合铸型及其铸件尺寸精度较高，铸件晶粒细化效果明显、力学性能优异。结论 通过多材料砂型增材制造层间加热与压实整体成形工艺研究，协调了高强度砂型的发气量和树脂量，进一步推动砂型增材制造技术向绿色化、柔性化和高性能制造方向创新发展。

Integral Forming Process of Interlayer Heating and Compaction in Multi-material Sand Additive Manufacturing

With respect to the problems of poor interlayer bonding and difficult coordination of resin content and gassing volume in the sand printing process, the work aims to propose an integral forming process of interlayer heating and compaction for multi-material sand additive manufacturing to realize high performance fabrication of multi-material sand molds. Based on the multi-material sand heating and compaction integrated forming device, the mechanical properties of the sand mold were regulated by optimizing and matching the parameters of the heating and compaction integrated forming process, such as the roller rotation speed, roller diameter and heating temperature, and the application was verified through casting test. The spinning roller compaction was used to assist the sand spreading. Under the conditions of the roller diameter of 60 mm and the roller speed of 3 r/s, the sand spreading effect was the best, the sand strength was the highest and the sand permeability met the casting requirements. For the 1.5 mm thick composite sand mold of the lamellar stacked structure, the preferred integral forming process parameters for interlayer heating and compaction were interlayer heating temperature of 150 ℃, roller diameter of 60 mm and roller speed 2 r/s. It was verified that the integrated forming process of interlayer heating and compaction could produce high-quality multi-material composite sand molds with good dimensional accuracy and performance of both sand molds and castings. The 1.5 mm thick lamellar stacked structure of the composite sand mold and its castings had high dimensional accuracy. The grain refinement effect of the castings was obvious and the mechanical properties of the castings were excellent. Through the research on integral forming process of interlayer heating and compaction for multi-material sand additive manufacturing, gassing volume and resin content of the high-strength sand mold are coordinated, further promoting the innovative development of sand additive manufacturing technology in the direction of green, flexible and high-performance manufacturing.