Research On The Model Of STEP-NC Interpreter

STEP-NC(ISO 14649), the data model standard of the computerized numerical control was constituted by ISO/TCI84/SC1. STEP-NC is an extension of STEP that organizes manufacturing operations into a series of "working steps." Each step defines an operation that can be performed on a CNC machine tool. The working steps defined by STEP-NC are equivalent to the machining orders represented by traditional M and G codes. However, unlike M and G codes, the working steps embody the three-dimensional geometry information, tool requirements information and feature definition information so that the machine tool can dynamically plan an operation and intelligently re-plan an operation using the available resources.In this dissertation, we introduced the source, the background, the meaning of the subject and the current research situation of STEP-NC standard both at home and abroad, and then recommend application activity model, application reference model, application interpret model in detail. Through these, the application protocol (AP238 ), using standard, function unit, and file structure of STEP-NC standard can be made clearer.On the base of the further research of STEP-NC standard, we set up the interpreter model composed of EXPRESS interpreter, Code interpreter, Scheduler, Tool path generator, Executor and Monitor and CNC system based on PMAC. We realize how to draw process information from STEP-NC file into the SQL database and how to draw the data from the database. According to processing method, processing technology and cutter message described in the STEP-NC file, the interpreter create NC order to drive the numerical control machine tool to process work-piece.In this dissertation, we start with the study of STEP-NC standard and set up the systematic structure model of numerical control based on STEP-NC principle and method. From the view of technology, we confirm the rational and feasibleresearch approach of numerical control and develop the overall scheme. In this way, we can develop our own numerical control system based on STEP-NC, which fill the gap that our country is in this domain and narrow the gap with developed countries.