【作者】 宋寒；

【导师】 彭芳瑜；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2007， 硕士

【摘要】 近年来欧、美、韩等工业发达国家面向现代计算机数控系统提出一种新的数据接口规范,即STEP-NC,用以取代沿用已久的ISO 6983(G代码)。它于1996年制定的,迄今己完成了部分标准化工作,其中的铣削和车削的数据模型己基本完善。STEP-NC基于制造特征(manufacturing features)进行编程,而不是直接对刀具运动进行编程。它包含了工件的所有加工任务,通过这一系列加工任务,对从零件毛坯到最终成品所有的操作加以描述,提供了更高层次的信息给加工车间。本文从总体上介绍了基于Linux-RTAI实时操作系统对开发STEP-NC数控系统在实时性方面的优势,分析了STEP-NC数控系统的用户层、控制层、内核层三层软件结构以及每一层的特点。其中重点介绍了用户层中STEP-NC各功能模块的特点并简要阐述了内核层RTAI实时内核的抢占式调度算法。对STEP-NC信息提取的方法进行了分析比较,简单分析了基于ROSE C++类库开发的ST-Developer软件在信息提取方面的优缺点。本文采用的方法是以EXPRESS语言向C++语言的映射为基础,建立了C++类库,作为STEP-NC的C++数据模型,详细描述信息提取的流程。同时,也对面向STEP-NC加工工步的车削轨迹的规划以及生成方法进行了一定的讨论。针对基于STEP-NC特征的切削参数优化问题,以切削速度和进给量为优化变量,以加工时间和加工成本综合优先建立多目标函数,并且从刀具和机床多方面对数学模型加入约束,建立切削参数优化模型。分析认为在数学模型中,切削长度L是对优化结果影响最大的参数,因此根据STEP-NC中关于几何轮廓的数据结构的定义,将切削优化数学模型和STEP-NC加工特征结合起来,并用基因遗传算法求解。最后在STEP-NC车削原型系统上对本文中所阐述的STEP-NC车削系统的功能模块进行验证,并给出了相关模块的实例。更多还原

【Abstract】 In recent years, Europe, America and Korea etc industrial developed country put forward a new criterion of data interface, namely, STEP-NC (ISO 14649), in order to replace ISO 6983 (G code) that have already used in a long time. It was drew up in 1996, and part work of standardize has been completed heretofore, in which data model of milling and turning have approximately completed. STEP-NC carries on program according to manufacturing features, but not to movement of tool directly. It includes all processing mission of workpiece, through a series of processing mission, describing all operation from the part of rough to final product and providing higher level information to the workshop of machining.This thesis introduces the advantage in real-time as developing the STEP-NC based on the Linux-RTAI real-time OS and analyzes the three-layer structure of STEP-NC, which contained User Layer, Control Layer and Kernel Layer. Among which the characteristic of STEP-NC modules embed in the User Layer is mainly discussed, at the same time, describing the preemption scheduling of RTAI kernel.Comparing the common method of information extraction, this thesis simply analyzes the advantage and disadvantage of ST-Deveploer based on ROSE class lib. The way to extract information in this thesis is based on the mapping form EXPRESS to C++, building a C++ lib as the STEP-NC mathematics model, and describing the process of information extraction. At the same time, this thesis also discusses the plan and generation of turning toolpath facing working-steps.Aiming at the optimization of cutting parameters based on STEP-NC features, the cutting speed and feedrate are regarded as the variables,and the cutting parameters optimization model can be built though using muti-objective function consists of less machining time function and less machining cost function, and the constraints mainly come from the tools and machines. According to analysis, the cutting distance L is regarded as the parameter which has most influence on the optimization result. So according to the description of geometry profile in STEP-NC, the cutting parameter model and the STEP-NC features can be contacted, and the using the Genetic algorithm to get the results.The realization of the related modules in the STEP-NC turning prototype system is discussed in the end.更多还原