回转面刀具侧铣叶轮叶片曲面的刀位规划研究

发布时间：2018-09-01 20:24

【摘要】：叶轮类复杂零件加工是数控技术研究领域的重点,其加工难点主要体现在叶片截面薄、曲面形状复杂、刀轨干涉严重等方面。与传统加工方式相比,侧铣加工具有工作效率高、表面光洁度好、加工成本低等优点,五坐标数控侧铣加工叶轮叶片已经成为一种趋势。侧铣加工的刀具通常以圆柱刀、圆锥刀等为代表的回转面刀具。叶轮类零件叶片曲面多为非可展直纹面,侧铣加工时存在着原理性误差。鉴于此,本文以圆锥刀为主要研究对象,探索适用于回转面刀具的共性的刀位规划方法。论文根据给出的叶轮叶片曲面的离散数据点并结合叶片曲面结构特点及CATIA功能特点,采用三次准均匀B样条插值技术,建立叶轮叶片曲面的数学模型及实体模型,为后续工作奠定基础。利用粒子群优化算法对圆锥刀的侧铣刀位规划问题进行了研究。将刀轴上一点到圆锥面的距离定义为该点对应的当量半径,给出单个刀位的最优判定条件即刀轴上各点到直纹面的距离与该点当量半径之差的平方和为最小,从而将刀具包络面向直纹面的逼近问题转化为每个刀位最优判定条件的实现问题。给出基于粒子群优化算法的求解最优刀轴轨迹面的实现过程。结合刚体运动学及实验设计方法,提出另外一种刀轴轨迹的生成策略。将刀具轴线上诸点在设计曲面上的法向投影点的集合定义为法向映射曲线,并给出一种理论特征点的计算方法,进而提出另外一种单刀位最优性判定条件,即每瞬时法向映射曲线与特征线实现最小二乘逼近。利用刚体运动学方法将刀轴位姿用3个回转与3个平移运动参数描述,建立起单刀位优化条件与6个运动参数的非显性的函数关系。采用拉丁超立方的试验设计方法求解获得最优的刀轴轨迹面。
[Abstract]:The machining of complicated parts of impeller is the focus of numerical control technology. The difficulties of machining are mainly reflected in thin blade section, complex curved surface and serious interference of cutter track, and so on. Compared with traditional machining methods, side milling has many advantages, such as high efficiency, good surface finish and low processing cost, etc. It has become a trend for 5-axis NC side milling to machining impeller blades. Side milling tools are usually cylindrical knives, conical cutters, etc. as the representative of the rotary surface tools. The blade surface of impeller parts is mostly non-developable and straight, and there is a principle error in side milling. In view of this, this paper takes the conical cutter as the main research object, and explores the common tool position planning method suitable for the rotary surface cutter. According to the discrete data points of impeller blade surface and the characteristics of blade surface structure and CATIA function, the mathematical model and solid model of impeller blade surface are established by using cubic quasi-uniform B-spline interpolation technique. Lay the foundation for follow-up work. Particle swarm optimization (PSO) algorithm is used to study the side milling cutter position planning of conical cutter. The distance from one point on the cutter axis to the cone surface is defined as the equivalent radius corresponding to the point, and the optimal judgment condition of a single cutter position is given, that is, the sum of squares of the difference between the distance from each point on the cutter axis to the surface of the straight ridge and the equivalent radius of the point is the smallest. Thus, the approach problem of tool envelope facing straight surface is transformed into the realization of the optimal condition of each tool position. The process of solving the optimal tool path surface based on particle swarm optimization algorithm is presented. Combined with rigid body kinematics and experimental design method, another tool path generation strategy is proposed. The set of normal projection points of all points on the tool axis on the design surface is defined as a normal mapping curve, and a method for calculating the theoretical characteristic points is given, and then another criterion for determining the optimality of single tool position is proposed. That is, every instantaneous normal mapping curve and feature line achieve least square approximation. By using rigid body kinematics method, the position of cutter axis is described by three rotation and three translational motion parameters, and the non-explicit functional relationship between the optimization condition of single tool position and six motion parameters is established. The optimal tool path surface is obtained by using the Latin hypercube experimental design method.
【学位授予单位】：大连交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG54

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