【作者】 彭健钧；

【导师】 郭锐锋；

【作者基本信息】 中国科学院研究生院（沈阳计算技术研究所） ， 计算机应用技术， 2012， 博士

【摘要】 数控技术的飞速发展，使得企业可加工的工件品种繁多，形状各异。工件结构趋于复杂化和整体化，工艺难度大，加工过程复杂，这给数控加工技术提出了新的挑战，如何高质量、高效率、低成本地完成复杂工件的数控加工成为了必须攻克的难题。基于特征的加工是数控加工技术发展趋势之一，有利于复杂工件数控加工的数字化、集成化和自动化。识别出复杂工件产品的典型特征是特征数控加工的基础，加工特征对于数控加工的工艺的规划、数控代码的生成，以及装夹的分析都起到了重要的作用。对于航空、航天、汽车制造等领域的复杂工件，需要五轴数控机床进行加工。五轴数控机床比三轴数控机床增加了两个旋转自由度，可提高复杂工件的加工精度。但在提高加工效率、加工质量的同时，也给数控加工工艺规划、刀具轨迹的生成、数控加工仿真验证技术等增加了难度。在五轴数控机床加工中，刀具根据轨迹数据进行不停地旋转和移动运动，很容易与工件加工表面、数控机床的部件碰撞，数控机床的各运动部件间也可能发生碰撞。利用数控加工仿真验证系统建立虚拟加工环境，实现五轴数控加工仿真过程，能有效检测数控程序的正确性。本论文在分析国内外复杂工件数控加工研究现状的基础上，针对现有研究工作的问题和局限性，结合我所承担的国家重大专项和高档数控系统的发展需求，对基于特征的复杂工件数控加工及仿真验证关键技术展开研究工作。论文主要研究内容如下：1.基于特征的复杂工件数控加工系统框架。本文构造了基于特征的复杂工件数控加工系统的框架，整个系统以工件特征为驱动，给出了基于特征的自动工艺规划过程，基于特征简化和恢复技术的加工工序毛坯模型的制定，描述了基于特征的数控加工编程，给出了数控加工仿真验证系统的整体设计及原型系统实现。基于特征的复杂工件数控加工系统，可自动识别出工件的特征，减少了复杂工件加工的人工干预，有利于制定合理的加工生产方案，为生产加工提供正确高效的保障，提高了复杂工件的加工质量和加工效率。2.复杂工件特征识别关键技术的研究。本文提出了圆角特征、倒角特征、孔特征的自动识别算法，并可以通过设定特征的阈值，控制可识别特征的范围。基于复杂工件加工的要求，提出了特征简化和恢复的算法，制定了整体简化和分步简化两种方案，可对识别后的特征进行简化及选择性恢复简化后的特征。特征的识别、简化和恢复技术可加快复杂工件工艺规划和刀具轨迹生成的效率。3.复杂工件数控加工实体建模方法研究。本文基于四边形网格生成算法对物体表面进行网格划分，并提出了用于关键特征保持和基于物理网格节点调整算法进行网格质量优化，对夹具、工作台等形状不发生改变的机床部件建模，该方法受实体模型复杂程度的影响较小，算法的实现复杂程度较低；基于格栅Voxel实体模型对加工过程中形状发生改变的毛坯进行实体建模，实现了边界模型向实体模型的转换算法，对实体的表面进行离散从而实现模型的绘制。建立了五轴数控机床的运动学模型，描述了坐标变化的过程及运动关系，并以AC机床为例，建立了机床的几何模型和运动学模型。4.复杂工件数控加工仿真验证原型系统的建立。对刀具在运动过程中形成刀具扫描体的计算方法进行了研究，刀具在五轴数控加工中形成的刀具扫描体不规则，精确求解刀具扫描体复杂，本文采用离散分解法计算刀具扫描体，降低了刀具扫描体的计算复杂度；实现了基于格栅Voxel实体建模方法的材料去除动态仿真，并可以通过调整格栅的尺寸，实现显示精度的定制；建立数控机床部件的层次方向包围盒OBB树，利用分离轴碰撞检测方法进行粗判，快速检测出不发生碰撞的物体，提出了基于四边形网格分级碰撞检测算法进行细判，该仿真验证系统不仅能够检测实时碰撞，而且可以给出机床发生碰撞的具体部位。更多还原

【Abstract】 With the rapid development of numerical control technology, the enterprise canprocess various kinds of workpiece of different shapes. The structure of workpiecetends to become complicated and the integrated, difficult in technology and complex inprocessing, so it brings a new challenge to the CNC processing technology. How toprocess large workpiece of CNC with high-quality, high efficiency and low-cost hasbecome a more and more important theme. Feature-based machining is one of thedeveloping tendency of CNC machining technology, and it is benefitial to thedigitization, integration and automation of CNC machining for complex workpiece. Toidentify the typical characteristics of the complex workpiece of products is the basis ofthe Feature CNC machining. The characteristics of processing always plays animportant role for technology planning, CNC code generation, as well as the analysisof the clamping for the CNC machining.We need five-axis CNC machine tools to produce some complex workpiece. Thefive-axis CNC machining not only improves the quality of processing, but also brings atough challenge for the tool path planning and CNC machining geometric simulation.Therefore, the more complex the shape of the workpiece becomes, the morecomplicated the NC code will be. During the producing process of five-axis CNCmachining, as the tool rotates and moves continuously, it can lead to collision. CNCMachining Process Simulation System Verification System can create a virtualprocessing environment, so the five-axis CNC machining simulation process can berealized in order to detect the correctness of the CNC program effectively.While analyzing the present situation of CNC processing of complex workpiecehome and abroad, and focusing on the problems and limitations existing in the researchwork, combined with my commitment to the major national projects and thedevelopment needs of the high-grade digital system, I studies the CNC machining ofthe complex workpiece based on the characteristics and simulation verification keytechnologies. The specific content includes several parts as follows:1. The design of the CNC machining system of the complex workpiece based onthe features. The paper presents CNC machining system of the complex workpiecebased on the features, and identifies the characteristics automatically. The entire systemuses the features of workpiece as driven, and this paper presents the automaticplanning process based on the characteristics, processes a stock model based oncharacteristics of simplified and recover technical, describes the programming systemof NC machining based on the features, and establishes NC machining simulation system.2.Research on key technologies for feature recognition of complex workpiece.The paper presents the recognition algorithms for the blend, chamfer and hole features,and the algorithms control feature size by setting threshold value. Based on therequirement of the machining of complex workpiece, the paper presents featuresimplification and recovery algorithms, develops overall simplification and simplifiestwo scenarios after achieving recognition features to simplify and streamline aselective restore. Feature recognition, simplification, and recovery of process planningfor complex workpiece and tool path generation has played a very important role.3.Research on NC machining method of solid modeling of complex workpiece.The paper presents quadrilateral mesh generation algorithm and mesh qualityoptimization algorithm which is used in keeping key features and is based on physicalnetwork mesh node adjustment, and making models for machine workpiece that doesnot have shape change, such as fixture, and table. The effect of entity model complexdegree on the method is small and the algorithm of implementation complex degree islow. The paper presents grid Voxel entity model on stock for modeling. In processing,shape change of stock entity makes model occurs and the conversion algorithm ofboundary model to entity model has implemented on the real surface of drawn fordiscrete-time model. The paper establishes a five-axis CNC machine kinematics model,describes the process of change of coordinates and movement, and takes AC machineas an example, and establishes a geometric model and kinematic modeling of machinetools.4. Establishment of simulation system of NC machining of complex workpiece. Thepaper makes research on the tool in movement process and in the formed tool swept ofcalculation method because the accurate solution method is complex and cannot meetreal-time sexual of requirements. The paper presents decomposition method toapproximate solution calculation; the method of material based on the grid Voxel entityis implementated to remove dynamic simulation, and the precision of displayed can berealized by adjusting the size of mesh; the paper establishes NC machine workpiece oflevel direction surrounded box OBB tree by using separation axis collision detectionmethod for rough sentence, and proposed a hierarchical collision detection algorithmbased on quadrangle grid through outsourcing so it can not only detect collisions in realtime of the simulation system, and can give specific workpiece where machine collisionoccurs.更多还原