激光3D打印用覆膜砂的制备工艺研究

Study on Preparation Process of Precoated Sand for Laser 3D Printing

使用热法覆膜工艺开发适用于激光3D打印砂型砂芯用的覆膜砂烧结材料。以硅砂作为原砂,以PF-1904和PFR-1350两种热塑性酚醛树脂按1：1比例混合作为粘结剂,通过正交试验的方法探索最佳的覆膜工艺参数。结果表明,为获得较高的覆膜砂常温抗拉强度,宜选用的制备工艺参数为砂温180℃,树脂含量3%,加固化剂后混砂40 s,加硬脂酸钙后混砂时间30 s。覆膜砂经激光选区烧结后,其抗拉强度达到3.42 MPa,基本满足新材料的开发要求。

The precoated sand sintering materials which was suitable for laser 3D printing sand mold sand core was developed by using hot coating process. With silica sand as raw sand and two kinds of thermoplastic phenolic resin of PF-1904 and PFR-1350 mixed at hl proportion as binders, the optimal parameters of the coating process were explored by the orthogonal experiment method. The results show that in order to obtain high tensile strength of precoated sand at room temperature, the preparation parameters should be chosen as sand temperature of 180 ℃, resin content of 3%, mixing sand for 40 s after adding curing agent, and mixing sand for 30 s after adding calcium stearate. After laser selective sintering, the tensile strength of the coated sand reaches 3.42 MPa, which basically meets the development requirements of the new materials.