介绍了将复合铸造技术运用到航空炸弹中的复杂工件,特别是大型薄壁铝合金舱体的优势。分析了石膏型熔模铸造结合真空增压技术的特点,同时,采用该技术研制大型复杂薄壁铝合金铸件,通过合理设计铸件浇注系统,选择铸型工艺,优化浇注工艺参数和严格控制固溶处理温度与校形时机,提高了铝合金的充型能力,改善了铸件的致密度和针孔度,解决了大型薄壁铸件充型及内部质量难以控制的难题。

The advantages of investment casting applied to complicated workpieces,especially a large-scale thin-walled aluminum alloy cases,of aerial bombs were discussed.The characteristics of plaster mold investment casting combined with vacuum pressurization technology were analyzed.Meanwhile,by reasonably designing a casting pouring system,selecting pouring processes,optimizing pouring process parameters and precisely controlling solid solution treatment temperature and correction time,the investment casting technology improved the filling capacity,compactness and porosity of the large-scale thin-walled complicated aluminum alloy casting.The problems of control difficulty in filling and internal quality of the large-scale thin-walled casting were solved.

利用FLOW-3D软件,对某本体铸件生产过程中出现的缩孔及疏松缺陷进行了模拟。模拟结果显示,在缺陷一侧增加浇口,同时对各浇冒口横截面及距离进行相应调整,缩孔及疏松缺陷消除。验证结果表明,根据模拟结果对石膏型低压铸造工艺进行优化后,试制的某本体铸件未见缩孔及疏松等铸造缺陷。

The shrinkage defects of body casting during practical production were simulated by FLOW-3D software. The results show that the shrinkage defects are eliminated effectively by adding a gate on one side of casting defects,and at the same time making the corresponding adjustment to the riser size and distance. The production practice indicates that the plaster casting process can be optimized by computer simulation,which can conveniently and quickly solve the problems of casting.

背景：目前，有关CAD/CAM系统与失蜡铸造法对边缘适合性影响的对比有较多研究，研究结果有着较大差异。目的：比较3 Shape CAD/CAM系统与失蜡铸造法制作钴铬金属烤瓷单冠基底冠冠边缘的适合性。方法：按标准预备1颗离体上颌第一前磨牙，用双色硅橡胶法制取50付超硬石膏模型，随机分为CAD/CAM组与铸造组，均以石膏模型为制作模型，CAD/CAM 组采用光学扫描仪获取数字印模，计算机设计制作，数控铣床直接切削完成基底冠；铸造组采用传统失蜡铸造法制作金属基底冠。待基底冠完全就位后，用轻体型硅橡胶复制边缘间隙，再用咬合型硅橡胶进行包埋，用体视显微镜测量冠边缘间隙的厚度。结果与结论：CAD/CAM组垂直间隙为(34.67±7.48)μm，铸造组垂直间隙为(53.70±9.64)μm，两组比较差异有显著性意义(P<0.05)；CAD/CAM组水平间隙为(37.61±7.63)μm，铸造组水平间隙为(53.02±10.65)μm，两组比较差异有显著性意义(P <0.05)。表明3 Shape CAD/CAM系统制作的钴铬金属单冠基底冠边缘适合性在临床可接受范围内，均小于120μm，且CAD/CAM系统制作的金属基底冠边缘适合性明显优于铸造法制作的基底冠。

BACKGROUND:At present, the confrontation of CAD/CAM systems and the lost wax casting method for marginal adaptation has been widely concerned, but the results are controversial. OBJECTIVE:To compare the marginal adaptation of single cobalt-chromium PFM crowns produced by 3 Shape CAD/CAM systems and the lost wax casting method. METHODS: A maxilary first premolar was prepared according to the standards. 50 resin-generation models were created by bi-color silicone rubber method and randomly divided into two groups: CAD/CAM group (A1-A25) and cast group (B1-B25). Al the models were cast in plaster. In CAD/CAM group, the digital impressions were obtained by optical scanning, then designed through computer and cut directly by NC miling machine. In cast group, metal ceramic crowns were made by the lost wax casting method. When crowns were al seated on the working dies, the marginal gaps were copied with light silicone rubber and then embedded with occlusal silicone rubber. The thickness of cr