精密卧式加工中心整机静动刚度正向设计方法研究

发布时间：2018-07-07 23:26

本文选题：精密卧式加工中心 + 静、动刚度　；参考：《天津大学》2016年博士论文

【摘要】：精密卧式加工中心作为装备制造业的“工作母机”,其发展水平对我国的装备制造业的整体水平有着直接的影响。整机静动刚度是保证其加工精度的关键因素。目前国内的静动刚度设计多基于经验进行类比设计,缺乏系统化、定量化、快速满足用户需求的设计方法。为此,本文以用户需求的整机静动刚度为目标,系统地研究了精密卧式加工中心整机静动刚度正向设计方法,取得了如下成果:1.提出了一种新的表示精密卧式加工中心部件静刚度的方法。即将部件特定位置处的静刚度值作为静刚度系数来表征部件静刚度,这些位置既与末端静刚度直接相关,又能够代表部件自身。这种方法有助于在设计初期仅有整机基本尺寸的情况下将静刚度的物理模型抽象成数学模型,也能够成为将来部件详细结构设计的目标。2.以静刚度系数表征部件静刚度为基础,利用多体系统理论,建立了整机静刚度模型。在建模的过程中,考虑到了结构件的柔性,将影响因子加入其中来描述一个位置受到的作用力对另一个位置的变形的影响。通过与整机静刚度实验进行对比,验证了模型的正确性。该模型能够适用于机床设计的骨架模型阶段,定性和定量的反映了“框中框”式精密卧式加工中心的静刚度特性,同时也反映出了机床的基本尺寸对整机静刚度的影响。3.提出了精密卧式加工中心整机静刚度匹配设计的方法。在骨架模型阶段,以用户需求的整机静刚度为目标,利用整机静刚度数学模型进行匹配设计,得到各部件静刚度值。在匹配过程中,采用试验设计的方法分析了各部件静刚度对整机静刚度的贡献率,发现了其中的薄弱环节。通过仿真实例,说明了该匹配方法的可行性和有效性。4.基于CAD/CAE联合仿真分析平台,利用NSGA-II优化设计方法计算出了与静刚度值相对应的结构件外形结构设计和内部筋板布局。进而计算出了常用的结构件静刚度所对应的所有结构方案,形成了结构件的结构方案数据库。这样,以整机静刚度为目标,匹配得到了各部件的静刚度,并以这些部件静刚度为目标,选出了各结构件的结构方案,最终完成了整机静刚度的正向设计。5.构建了整机参数化模型,利用CAD/CAE联合仿真分析平台研究了各结构件质量对整机固有频率的影响规律;采用试验设计的方法进行了各结构件质量对整机固有频率的贡献率分析,发现了床身质量,尤其是后床身质量是影响整机固有频率的关键环节,进而提出了整机动刚度匹配设计方法:在整机静刚度匹配设计完成的情况下,以给定的整机一阶固有频率为目标,利用床身质量等与一阶固有频率的函数关系,确定出满足要求的床身质量与结构尺寸。上述研究成果为精密卧式加工中心的正向设计提供的理论支撑,并开发出了相应的正向设计软件,应用于企业的精密卧式加工中心设计当中。
[Abstract]:As the "working mother machine" of the equipment manufacturing industry, the development level of the precision horizontal machining center has a direct impact on the overall level of the equipment manufacturing industry in China. The static and dynamic stiffness of the whole machine is the key factor to ensure the machining accuracy. At present, the static and dynamic stiffness design in China is based on experience, lacking of systematic, quantitative and rapid design methods to meet the needs of users. Therefore, aiming at the static and dynamic stiffness of the whole machine, this paper systematically studies the forward design method of the static and dynamic stiffness of the whole machine in the precision horizontal machining center. The results are as follows: 1. A new method for representing static stiffness of precision horizontal machining center parts is presented. The static stiffness at a particular position of the component is taken as the static stiffness coefficient to characterize the static stiffness of the component. These positions are directly related to the static stiffness of the end and can also represent the component itself. This method can be used to abstract the physical model of static stiffness into a mathematical model when the basic dimensions of the whole machine are only available at the beginning of design, and it can also become the target of the detailed structural design of components in the future. The static stiffness model of the whole machine is established by using the theory of multi-body system based on the static stiffness coefficient which represents the static stiffness of the components. In the process of modeling, considering the flexibility of the structure, the influence factor is added to describe the effect of the force acting on one position on the deformation of the other position. The correctness of the model is verified by comparing with the static stiffness experiment of the whole machine. This model can be used in the frame model stage of machine tool design. It reflects the static stiffness characteristics of the "frame in frame" precision horizontal machining center qualitatively and quantitatively, and also reflects the influence of the basic size of the machine tool on the static stiffness of the whole machine. The design method of static stiffness matching for the whole machine of precision horizontal machining center is put forward. In the stage of skeleton model, the static stiffness of the whole machine is taken as the target, and the matching design is carried out by using the mathematical model of the static stiffness of the whole machine, and the static stiffness values of each component are obtained. In the matching process, the contribution rate of the static stiffness of each component to the static stiffness of the whole machine is analyzed by the method of experimental design, and the weak links are found. The feasibility and effectiveness of the matching method are illustrated by a simulation example. Based on CAD / CAE joint simulation and analysis platform, the shape and structure design and internal stiffener layout of structural parts corresponding to static stiffness are calculated by using NSGA-II optimization design method. Then, all the structural schemes corresponding to the static stiffness of structural components are calculated, and the database of structural schemes is formed. In this way, the static stiffness of each component is matched with the static stiffness of the whole machine, and the structural scheme of each structural part is selected with the static stiffness of these components as the target. Finally, the forward design of the static stiffness of the whole machine is completed. The parameterized model of the whole machine is constructed, and the influence of the quality of each structural part on the natural frequency of the whole machine is studied by using the CAD / CAE joint simulation and analysis platform, and the contribution rate of the quality of each structural part to the natural frequency of the whole machine is analyzed by the method of experimental design. It is found that the quality of the bed, especially the mass of the back bed, is the key link that affects the natural frequency of the whole machine, and then the matching design method of the whole maneuvering stiffness is put forward: when the static stiffness matching design of the whole machine is completed, Aiming at the given first order natural frequency of the whole machine, the mass and structure size of the bed are determined by using the function relationship between the mass of the bed and the natural frequency of the first order. The above research results provide theoretical support for the forward design of the precision horizontal machining center, and develop the corresponding forward design software, which can be applied to the design of the precision horizontal machining center in the enterprise.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG659

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