Research And Development Of Process Information Extraction And Parameters Optimization On STEP-NC Turning System

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.