基础不均匀沉降对机床加工精度的影响

发布时间：2018-03-14 16:54

本文选题：龙门式机床　切入点：基础混凝土徐变　出处：《北京工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：高精度机床是加工高精度工件的重要基础,对精度要求很高,而重型高精度机床本身的自重很大,会对基础产生很大的作用力,随着时间累积导致基础发生变形,而基础变形又会对机床产生影响,如果机床变形,则机床加工精度难以保证,因此有必要研究机床和基础直接的影响规律,特别是重型数控机床,对加工精度有较高的要求。本文基于混凝土徐变理论,选取合适的混凝土徐变经验公式计算混凝土的等效弹性模量,利用有限元分析软件分析机床自重提供的作用力对基础在不同等效弹性模量下的变形,从而得出基础在机床自重下随时间的变形曲线,并通过实验验证方法的可行性。建立机床等效模型,龙门式机床简化为梁单元的框架结构,然后利用应用非线性有限元中的路径跟踪方法计算由基础变形引起的机床变形。针对的研究对象为重型龙门式机床,研究机床自重引起的基础变形,然后分析基础的变形对机床的影响。文中阐述了多种混凝土徐变计算理论及经验公式,根据实测数据及经验采取了工程应用最为广泛的方法估算混凝土徐变;并结合有限元软件workbench分析基础变形,通过对比计算结果和实际测量的基础变形数据可选取符合变化规律的数据;并对比多种非线性有限元求解方法,分析了载荷控制法、位移控制法以及弧长法的特点,选取合适的路径跟踪方法求解机床模型变形,得到了基础变形与机床变形之间的关系。根据得到的结果基础在受力初期变形比较快,可以制定预压方案消除受力初期基础的变形,并根据变形规律调整机床的精度。同时根据非线性有限元分析得出的机床变形,可针对变形比较大的部位加固机床结构,减少机床受基础变形的影响。
[Abstract]:High precision machine tool is the important foundation of machining high precision workpiece, which requires very high precision. However, heavy duty high precision machine tool itself has a very large weight, which will produce great force on foundation, which will result in deformation of foundation with time accumulation. And the foundation deformation will have an effect on the machine tool. If the machine tool is deformed, it is difficult to guarantee the machining accuracy of the machine tool. Therefore, it is necessary to study the direct influence law of the machine tool and foundation, especially the heavy-duty numerical control machine tool. In this paper, based on the creep theory of concrete, the equivalent elastic modulus of concrete is calculated by selecting appropriate empirical formula of concrete creep. The finite element analysis software is used to analyze the deformation of the foundation under different equivalent elastic modulus by the force provided by the weight of the machine tool, and the deformation curve of the foundation with time under the weight of the machine tool is obtained. The feasibility of the method is verified by experiments. The equivalent model of the machine tool is established, and the gantry machine tool is simplified to the frame structure of the beam element. Then using the path tracking method in the nonlinear finite element to calculate the deformation caused by the foundation deformation. The research object is the heavy-duty gantry machine tool, and the foundation deformation caused by the self-weight of the machine tool is studied. Then, the influence of foundation deformation on machine tool is analyzed. Many kinds of concrete creep calculation theories and empirical formulas are expounded, and the most widely used method to estimate concrete creep is adopted according to the measured data and experience. Combined with the finite element software workbench, the foundation deformation data can be selected according to the changing law by comparing the calculation results with the actual measured basic deformation data, and the load control method is analyzed by comparing various nonlinear finite element solution methods. Based on the characteristics of displacement control method and arc length method, a suitable path tracking method is selected to solve the deformation of the machine tool model, and the relationship between the foundation deformation and the deformation of the machine tool is obtained. The preloading scheme can be formulated to eliminate the deformation of the initial foundation and adjust the accuracy of the machine tool according to the deformation law. At the same time, according to the nonlinear finite element analysis, the deformation of the machine tool can be strengthened for the parts with large deformation. Reduce the influence of foundation deformation on machine tool.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU433;TG502

【相似文献】