机床立柱铸造过程数值模拟研究

发布时间：2018-07-29 11:56

【摘要】：为了适应当今工业朝着高、精、尖方向发展的需要,机床作为工业之母在这一进程中扮演着举足轻重的角色。立柱作为大型高档数控机床的主要部件之一,立柱铸件生产质量的优良与否与数控机床的工作寿命及其加工对象的精度高低是息息相关的。随着工业产品对零件加工精度的要求日趋严苛,大型高档数控机床对于立柱部件的刚度、抗偏载能力以及定位精度等各方面性能也提出了更高的要求。因此,要保证立柱具有足够的强度和加工精度,就要求在立柱的铸造过程中防止铸造缺陷的产生。传统的铸造方法一般都是依靠经验积累来进行工艺设计,这样不仅容易造成材料的极大浪费而且很难保证产品的质量。本文以27系列龙门镗铣床立柱为研究对象,采用PROCAST数值模拟仿真软件对立柱的铸造过程进行数值模拟研究,并且根据企业的生产条件设计、改进了生产工艺,减少了铸造缺陷的产生。本文首先根据“卧浇底注”浇注理论对立柱的浇注系统进行了设计,并通过Proe5.0建立了初始方案的三维模型,然后在有限元铸造工艺数值模拟系统PROCAST中对立柱的铸造过程进行数值模拟。通过分析立柱充型过程的温度场与速度场变化以及凝固传热过程的温度场变化,最终对铸件可能会产生的各种铸造缺陷进行了可靠的模拟预测。本文通过对模拟结果进行分析,讨论了浇道对铁水充型流速的影响以及铸件凝固速度对铸件缺陷的影响;通过多次试验后对初始方案进行了改进,确定了比较合理的进水方式以及冷铁、通气冒口的分布方式;通过有限差分模拟软件Anycasting对改进方案进行了验证,两种软件对铸件缺陷的预测具有较好的一致性。最后采用与仿真实验完全相同的铸造工艺制作了实验件对改进工艺进行了验证,实验结果有力验证了模拟仿真分析结果的可靠性。通过数值模拟仿真软件对铸件的铸造工艺进行设计可以快捷直观地观察到该工艺生产质量的好坏,以便工程师随时对工艺进行调整。这样不仅可以缩短设计时间周期,还可以帮助企业在降低物料成本的前提下提高铸件的良品率,对于企业生产复杂大型铸件具有很好的指导意义。
[Abstract]:In order to adapt to the development of industry in the direction of high, fine and sharp, machine tools play a pivotal role in this process as the mother of industry. As one of the main components of large and high-grade NC machine tools, the quality of pillar castings is closely related to the working life of NC machine tools and the precision of machining objects. With the increasingly stringent requirements of industrial products for parts processing accuracy, large high-grade CNC machine tools have put forward higher requirements for the stiffness, offset resistance and positioning accuracy of column components. Therefore, to ensure that the column has sufficient strength and machining precision, it is necessary to prevent casting defects in the casting process. The traditional casting methods usually rely on the experience accumulation to carry out the process design, which is not only easy to cause great waste of materials, but also difficult to guarantee the quality of the products. This paper takes the column of 27 series gantry boring and milling machine as the research object, uses the PROCAST numerical simulation software to carry on the numerical simulation research to the vertical column casting process, and according to the enterprise production condition design, has improved the production craft, The production of casting defects is reduced. In this paper, the pouring system of the column is designed according to the theory of "horizontal bottom pouring", and the 3D model of the initial scheme is established by Proe5.0. Then the casting process of column is numerically simulated in the finite element casting process simulation system (PROCAST). By analyzing the change of temperature field and velocity field in the filling process of column and the change of temperature field in solidification and heat transfer process, a reliable simulation and prediction of various casting defects may be made. Through the analysis of the simulation results, the influence of the sprue on the filling velocity of the hot metal and the effect of the casting solidification rate on the casting defects are discussed, and the initial scheme is improved after many experiments. The reasonable influent mode and the distribution mode of cold iron and air riser are determined, and the improved scheme is verified by finite difference simulation software Anycasting. The two kinds of software have good consistency in predicting casting defects. Finally, the improved process is verified by using the same casting process as the simulation experiment, and the result of the experiment can verify the reliability of the simulation analysis result. The casting process can be designed by numerical simulation software, and the quality of the casting process can be observed quickly and intuitively, so that the engineer can adjust the process at any time. This can not only shorten the design time cycle, but also help enterprises to improve the quality of castings on the premise of reducing the cost of materials. It has a good guiding significance for enterprises to produce complex large castings.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG24

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