基于资源配置空间区域分割的加工特征识别技术

Machining feature recognition (MFR) is well known as a key issue for seamless integration of CAD/CAPP, but the existent researches about it have not yet led to much application in industry, mainly because of the alternative dilemma of geometry's interpretations in MFR that is conducted in a way independent of the manufacturing resources really used in machining operations. To address this issue, this project proposes to develop a MFR technique for the previously specified resources based on the idea of machine-driven planning, which focuses on matching between workpiece shapes and resource motions under various configurations. Firstly, the project will study the precise representation for manufacturing capability of the machining resources like machining tools, fixtures and cutting tools by means of configuration space (CS). Secondly, some key issues relating to the objective will be elaborated, like setup candidate selection based on geometric analysis to workpiece, generation of CS images of workpiece surfaces, and partition of motion domains for features (MDF) in CS. Finally, according to the previously created associations between workpiece surfaces and resources as well as their motions, the project will develop a series of algorithms that fulfill the MFR task, including feature region decomposition of the whole machined surface area on the workpiece, feature volume generation by constructing the swept volume from the configurations in a MDF, and determination of the precedence order for the identified machining features. In addition, the project will also develop a prototype MFR software system to validate the methodologies put forward in the research with practical case studies. The successful implementation of the project would not only archive a great improvement to CAD/CAPP integration, but also establish a theoretic foundation for the direct process planning based on real manufacturing resources.

加工特征识别是实现机加工中CAD/CAPP无缝集成的关键环节，然而目前独立于制造资源的通用加工特征识别研究工作遭遇资源多选困境，仍未形成普遍应用的技术。本课题采取面向实际设备资源的机器驱动式工艺规划思想，通过研究资源配置运动与工件几何形状之间的匹配关系，形成有效地支持特定机床环境下工艺规划的加工特征自动识别技术。课题首先将基于配置空间方法，研究机床、夹具和刀具等资源的制造能力精准表达方法。其次将研究基于几何分析的候选装夹选择、工件表面在配置空间中的映像生成以及配置空间中特征运动区域分割等问题。最后课题将基于工件表面与资源及其运动的关联关系，研究整体加工表面的特征区域划分、特征体生成及特征加工顺序确定等问题。此外，课题还将开发加工特征识别软件原型系统，对理论方法研究成果进行检验和应用验证。本课题预期成果不仅有望推进CAD/CAPP有效集成，同时为面向实际制造资源的直接工艺规划奠定理论基础。

加工特征是零件几何模型中与具体加工操作对应的部分表面，自动识别加工特征是实现零件设计与加工制造无缝集成的关键技术之一。然而，传统加工特征识别方法对相交特征和资源多选等问题不能有效处理。本课题基于资源配置运动与工件几何形状之间的匹配关系，约束相交特征多义和制造资源多选范围，形成有效地支持工艺规划的加工特征自动识别技术。. 为此，本项目开展了若干研究工作。首先，研究了制造资源能力建模和加工特征定义方法。其次，研究了材料切除区域的单元剖分与特征组合方法。此外，针对识别的加工特征，还研究了装夹规划与加工操作顺序生成方法。最后，基于材料单元优化组合方法，开发了三维加工特征识别软件原型系统。本项目在执行上述研究任务的过程中取得的下列主要研究成果：（1）基于Mill/Turn机床运动特征的车铣切削体分离方法；（2）基于等参曲线簇的配置空间表示及其生成方法；（3）基于刀具接近方向的车削和铣削材料体的单元剖分方法；（4）具有多极面车铣复合零件的最大可车状态自动提取方法；（5）基于分层树搜索的车削特征识别方法；（6）基于材料单元组合优化的车铣复合加工特征识别方法；（7）精度约束下装夹规划和工序顺序优化求解方法。在上述研究成果基础上，课题组开发了相关软件原型系统，其功能包括加工特征识别、工艺路线优化、三维切削仿真与加工参数选择、以及基于离散系统建模的加工工艺流程仿真，并将其应用于若干典型零件的加工工艺规划。. 本项目在克服相交特征识别难点和解决特征-资源映射多选问题等方面取得了一些进展，为CAD/CAPP无缝集成提供了理论和方法基础。具体地，这些进展主要体现在：基于机床和刀具运动的材料网格剖分简化了相交特征识别难度；基于组合优化的特征识别方法较好地解决了相交特征多义性问题；精度约束下装夹和工序顺序优化方法适合处理资源多选问题并保证加工精度质量。