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中小型球铁件无冒口铸造工艺可行性研究报告DOC

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本课题以球铁箱盖件为研究对象,研究中小型球铁件无冒口铸造的可行性。 球墨铸铁箱盖件材质为 QT450-10,重约 38kg,结构较为对称,平均壁厚较小 为 12mm,最薄处壁厚为 10mm,最厚处达到 28mm。箱盖件的工作环境恶劣,而 且铸件内部薄壁与厚壁交错相连,因此要求铸件内部不能有缩松缩孔缺陷,采 用传统的顺序凝固设计浇冒口系统很难对铸件内部厚壁部分进行补缩,最后在 铸件内部易形成缩松缩孔缺陷。 本文首先对均衡凝固技术和无冒口工艺以及球墨铸铁的凝固特性进行分析, 均衡凝固技术与无冒口铸造工艺的原理都是要求充分利用铸件内部的石墨化膨 胀进行自补缩,浇冒口系统只是用于补缩铸件前期的液态收缩,浇冒口系统则 需要在铸件内部发生石墨化膨胀时及时凝固关闭,防止由于石墨化膨胀将型腔 内的金属液反补进入浇注系统;其次以箱盖件为对象,应用均衡凝固技术和无 冒口铸造工艺对箱盖件进行工艺设计,均衡凝固的浇冒口系统尺寸为,直浇道 截面尺寸为 Φ22mm,横浇道梯形截面尺寸为 16/18×20mm,内浇道截面尺寸为 14×6mm,配合短薄宽的冒口颈的尺寸为 7mm,厚度为 3mm,宽度为 18mm, 冒口尺寸为 Φ40mm;无冒口工艺设计的浇注系统的尺寸为,直浇道截面尺寸 为 Φ26mm,横浇道梯形截面尺寸为 16/20×28mm,内浇道截面尺寸为 18×8mm。 最后运用铸造模拟软件 Procast 对铸造工艺进行数值模拟,结果表明采用均衡凝 固技术和无冒口工艺设计均能消除原工艺存在的缩松缩孔缺陷,得到合格致密 的铸件。 通过对箱盖件的工艺设计可知,只要球铁铸件结构存在足够的薄壁部分, 铸件的质量周界商大于20kg/cm 3 ,中小型球墨铸铁件实现无冒口铸造是可行的。 实现中小型球铁件的无冒口铸造不仅可以简化铸造工艺,也大大提高了铸件的 工艺出品率,具有重要的实际意义。 关键词,箱盖件;球墨铸铁;均衡凝固技术;无冒口铸造;数值模拟III ABSTRACT The object of this topic is study for the feasibility of no riser casting process of small and medium sized ductile iron casting, the subject is a cover casting, which is made of QT450-10,weight about 38kg, and has a symmetric structure, the average thickness is 12mm,the thinnest and thickest thickness is 10mm and 28mm. It works in poor environment, so requires no shrinkage porosity in the casting. But there are thin walls and thick walls distribute in the casting, there will form shrinkage porosity when adopt the traditional directional solidification principle to design the casting process, because the gating system is difficult to feed the casting. Firstly the topic analyze the theory of proportional solidification technology, no riser process and the solidification behavior of ductile iron. The proportional solidification technology and no riser process utilize the graphite expansion to feeding the casting, the gating system is also used to feeding the preliminary shrinkage, and the gating system need to solid timely when the casting begins graphite expansion. Secondly the topic design the casting process of cover parts using the proportional solidification technology and no riser process, the gating system size of proportional solidification technology is : the size of sprue is Φ22mm,the size of runner is 16/18×20mm and the size of ingate is 14×6mm,with a riser sized Φ40mm,use a short thin and wide riser neck and its size is respectively 7mm ,3mm, and 18mm;the gating system size of no riser process is : the size of sprue is Φ26mm,the size of runner is 16/20×28mm and the size of ingate is 18×8mm,and using 7 outlet pieces on the top of casting and coordinate with chills. At last ,use the simulation software Procast to simulate the filling and solidification of the designed process, the result show there is no shrinkage porosity in the casting ,the filling process is smooth and the temperature field is reasonable and finally get a good quality of the casting. By designing the casting process of the cover, we know that if there are enough thin walls in casting, it is feasible to design the gating system without riser. It is significant to realize the no riser process , it can simplify the casting process and increase the production rate greatly. Key words: cover parts, ductile iron, proportional solidification technology, no riser process, numerical SimulationIV 目录 第一章 绪论.................................................................................................................. 1 1.1 课题的背景及意义 .............................................................................................. 1 1.2 球墨铸铁的概况 .................................................................................................. 2 1.2.1 球铁在国内外的发展历史 ........................................................................... 2 1.2.2 球铁在国内外的发展应用现状 ................................................................... 3 1.2.3 球铁的主要性能和特点 ............................................................................... 4 1.2.4 球铁的凝固收缩特点 ....................................................................................... 5 第二章 均衡凝固理论和大孔出流理论 ........................................................................... 7 2.1 铸件均衡凝固理论的发展及应用概况 .............................................................. 7 2.2 均衡凝固理论定义 .............................................................................................. 8 2.2.1 均衡凝固与顺序凝固的异同点 ................................................................... 9 2.2.2 均衡凝固与同时凝固的异同点 ................................................................... 9 2.3 均衡凝固技术 ...................................................................................................... 9 2.3.1 接触热节的形成 ........................................................................................... 9 2.3.2 均衡凝固技术的工艺原则 ......................................................................... 10 2.4 大孔出流理论 .................................................................................................... 13 2.4.1 孔口出流的实验 ......................................................................................... 14 2.4.2 浇口杯、直浇道、横浇道、内浇道四单元浇注系统的大孔出流 ......... 15 2.5 均衡凝固理论无冒口铸造工艺 ........................................................................ 18 2.5.1 无冒口铸造的工艺条件 ............................................................................. 19 2.5.2 无冒口铸造的浇注系统 ............................................................................. 20 第三章 实验方案的确定及数值模拟.............................................................................. 22 3.1 浇注温度对铸件缩松缩孔的影响 .................................................................... 22 3.1.1 实验方案的确定 ......................................................................................... 22 3.1.2 铸造工艺模拟 ............................................................................................. 22 3.2 内浇道数量对缩松缩孔的影响 ........................................................................ 33 3.3 均衡凝固原则设计箱盖件的浇冒口系统 ........................................................ 34 3.3.1 运用均衡凝固模数法计算冒口尺寸 ......................................................... 34 3.3.2 运用大孔出流理论计算铸件的浇注系统 ................................................. 36 3.3.3 铸造工艺模拟 ............................................................................................. 37 3.4 顺序凝固原则设计箱盖件的浇冒口系统 ........................................................ 41 3.4.1 箱盖件浇注系统尺寸的确定 ..................................................................... 41 V 3.4.2 顺序凝固原则冒口的设计 ......................................................................... 42 3.4.3 顺序凝固原则工艺设计模拟 ..................................................................... 42 3.5 箱盖件无冒口铸造工艺设计 ............................................................................ 47 3.5.1 无冒口铸造浇注系统的设计 ..................................................................... 47 3.5.2 无冒口铸造工艺设计模拟 ......................................................................... 48 第四章 全文总结及展望 ................................................................................................... 53 4.1 全文总结 ............................................................................................................ 53 4.2 展望 .................................................................................................................... 54