新型龙门式五轴联动混联机床机构设计及其基础理论研究

发布时间：2018-01-21 09:42

本文关键词： 混联机床奇异性运动学动力学虚功原理静刚度模态分析　出处：《中北大学》2017年硕士论文　论文类型：学位论文

【摘要】：细长结构件在航空航天、铁路运输、国防工业等领域具有广泛的应用。本文针对细长结构件进行高速加工时机床应满足的刚度重量比大、响应速度快、加工精度高等性能要求,将一种新型的混联机构作为混联机床机械本体,设计出一种新型龙门式五轴联动混联机床。其主要内容概括如下:进行了新型龙门式五轴联动混联机床机构的构型设计。运用螺旋理论分析了该机床实现3T2R型运动模式的原理,提出了驱动件的选取方法,分析了机床机构的奇异性,提出了减少奇异的参数设计条件。进行了新型龙门式五轴联动混联机床运动学分析。运用矢量代数法对机床进行了位置逆解计算,在已知机床刀尖点位置和动平台姿态的条件下求得各驱动副的输入量;运用影响系数法求得机构一阶运动影响系数矩阵——Jacobian矩阵和二阶影响系数矩阵——Hessian矩阵。进行了新型龙门式五轴联动混联机床动力学分析。运用虚功原理基于对机床机构整体虚能量的计算建立此新型龙门式混联机床机构动力学模型。给出了一个数值算例,用ADAMS仿真求证了此机床机构运动学、动力学分析模型的正确性。给出了对一个细长结构件进行钻孔加工的实例,得出了钻孔加工过程中运动学及驱动力的变化规律。进行了新型龙门式五轴联动混联机床的2-UPS+2-RPU并联机构静刚度分析。基于小变形叠加原理,分析各杆在其约束力螺旋(包括驱动螺旋)作用下产生的弹性变形,建立支链约束力螺旋刚度矩阵。通过动平台静力平衡及支链变形和动平台变形间的关系,建立机构的动平台位姿变化与外载荷关系,进而得到机构的整体柔度、刚度矩阵。得出约束力/矩对这类少自由度过约束并联机构的刚度和变形影响很大,且其弹性变形主要产生在约束力/矩轴线方向。对新型龙门式五轴联动混联机床进行了模态分析。基于ANSYS Workbench软件对新型龙门式五轴联动混联机床五种典型位置的模态进行了分析,确定在此位型下的前六阶固有频率及振型,通过振型云图及振动动画分析机床低阶振动规律,确定机床结构的薄弱环节,为新型机床的优化设计提供参考。本文设计的新型龙门式五轴联动混联机床,其两轴转动能力大约为±40°,解决了目前细长结构件的加工难题,具有重要的应用价值。
[Abstract]:Slender structural parts are widely used in aerospace, railway transportation, national defense industry and so on. In this paper, the machine tool should meet a large stiffness / weight ratio and fast response speed in high-speed machining of slender structural parts. In order to meet the requirements of high machining precision, a new type of hybrid mechanism is used as the mechanical body of the hybrid machine tool. A new type of gantry five-axis hybrid machine tool is designed. The main contents are summarized as follows:. The configuration design of a new type of gantry five-axis linkage machine tool is carried out, and the principle of realizing 3T2R type motion mode of the machine tool is analyzed by using the helical theory. The selection method of driving parts is put forward, and the singularity of machine tool mechanism is analyzed. The parameter design condition of reducing singularity is put forward. The kinematics analysis of a new type of gantry five-axis linkage machine tool is carried out. The inverse position solution of the machine tool is calculated by using vector algebra method. The input of each driving pair is obtained under the condition that the tip position of the machine tool and the attitude of the moving platform are known. The first order motion influence coefficient matrix and the second order influence coefficient matrix Hessian matrix are obtained by using the influence coefficient method. A new gantry five-axis linkage machine tool is developed. Dynamic analysis. Based on the calculation of the whole virtual energy of the machine tool mechanism, the dynamic model of this new type of gantry hybrid machine tool mechanism is established by using the virtual work principle. A numerical example is given. The correctness of kinematics and dynamics analysis model of this machine tool mechanism is verified by ADAMS simulation. An example of drilling for a slender structure is given. The variation law of kinematics and driving force in drilling process is obtained. A 2-UPS for a new type of gantry five-axis linkage hybrid machine tool is carried out. Static stiffness analysis of 2-RPU parallel mechanism based on the principle of small deformation superposition. The elastic deformation of each rod under the action of its binding screw (including the driving screw) is analyzed, and the stiffness matrix of the branch chain is established. Through the static balance of the moving platform and the relationship between the deformation of the branch chain and the deformation of the moving platform. The relationship between the position and pose of the moving platform and the external load is established, and the overall flexibility and stiffness matrix of the mechanism are obtained. It is concluded that the binding force / moment has great influence on the stiffness and deformation of this small degree of freedom over-constrained parallel mechanism. The elastic deformation is mainly produced in the direction of the binding / moment axis. The modal analysis of a new type of gantry five-axis linkage machine tool is carried out based on ANSYS. Workbench software is used to analyze the modes of five typical positions of a new type of gantry five-axis hybrid machine tool. The first six natural frequencies and modes under this position are determined, and the weak links of machine structure are determined by analyzing the low order vibration law of machine tool by mode cloud diagram and vibration animation. This paper designed a new type of gantry five-axis linkage machine tool, its two-axis rotation capacity is about 卤40 掳, which solves the processing problem of slender structural parts at present. It has important application value.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG502.1

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