复杂平板件V法铸造工艺探索与实践-材料加工工程专业论文.docxVIP

华 华 中 科 技 大 学 硕 士 学 位 论 文 I I 摘 要 近十年来，V 法铸造工艺在国内得到了快速发展，其铸件能获得精确的尺寸精 度和较低的表面粗糙度。然而，由于受到 EVA 薄膜延伸率的影响和铸型真空控制的 制约，V 法铸造在复杂铸件上的应用受到限制，阻碍了其工艺的进一步提升和生产 率的提高。 基于与湖南嘉禾众合铸业有限公司合作项目《木工机械铸件 V 法铸造技术合 同》，本课题结合复杂平板件 V 法铸造实践，开展对于 V 法铸型稳定性的研究，做 了以下工作： 首先对影响其工艺实施的铸型稳定性进行了分析，对造型、浇注过程中真空抽 气速率的变化规律和抽气量的需求进行了研究和计算；并通过对真空砂箱的结构设 计和其对铸型强度的影响进行了分析，为相关砂箱结构设计提供了宝贵的经验。 为了攻克 EVA 薄膜在复杂型面覆膜难的问题，笔者对武汉和北京两家国产薄膜 及日本进口薄膜进行覆膜成形拉伸性能测试。通过对比薄膜覆膜后成形效果及出现 的桥接、破口等缺陷，分析各型薄膜的特点并提出应对措施，为行业铸造复杂铸件 选取合适的薄膜提供了参考标准。 通过对具有复杂型面的木工机座双头大镂机进行 V 法铸造产品试制实践，铸造 出了尺寸精度高、表面粗糙度低的铸件样品，减少了铸件机加工余量，提高了工艺 出品率，并有效避免了铸件出现粘砂、气孔和大平面变形的缺陷。结合铸造工艺实 践，对产品结构进行优化设计，以进一步提高 V 法生产效率，具有实际应用价值。 关键词：V 法铸造 真空系统 砂箱结构 铸型稳定性 复杂平板铸件 II II Abstract In the past decade, the vacuum process with dry sand has been rapidly developed in our country. The casting could got the smooth surface and high dimensional accuracy. However, the further development of V process in complex casting is restricted by the problems of limited elongation of EVA plastic film and the influence of vacuum system. The project is based on the cooperation project with Hunan Jiahe Zhonghe Casting Ltd. the systematic research was carried out based on mold stability and combined practice in complex plate casting ，this paper completed the following works. Firstly, the mold stability which influence the implement of the technology were analyzed. The changing rules of vacuum air exhausting velocity during moulding and pouring were researched to calculate the quantity of air exhaust. Then suitable flask structure were designed and the influence factors of the mold stability were analyzed. Valuable experiences for flask design of the V process were summarized. In order to overcome the problem that EVA plastic film is hard to cover the complex mold, Two typical kinds of homegrown films and one kind of Japanese film were tested for stretching properties of film mulching. The stretching results of films mulching after heated were analyzed as well as the defects such as bridge tap and crevasse