Research And Development On Turning NC System Compiler Based On STEP-NC

STEP-NC is a new data interface standard between CAM and CNC that is established by the International Standards Organization recently. It is a STEP expansion in the field of CNC. STEP-NC relates design information and manufacturing information of the products in the form of oriented object, dispels the information flow bottleneck between CAX and CNC. The appearance of new generation based on STEP-NC will establish solid foundation for manufacture equipment in realization intelligent, integrated, networked. The machining procedure of STEP-NC numerical control system is the AP238 file that includes all the geometry information and craft information for machining the part. The decipher of AP238 file can't explain and execute line by line as G Code, and can only compile, thus the decipher process system of STEP-NC numerical control system was called as the compiler. The following work is accomplished around the design and realization of the compiler of the STEP-NC turning NC system in this thesis: Firstly, the thesis researches the STEP standard and its principle and method of conformance testing, analyzes the structure of AP238 neutral file, and divides STEP-NC AP238 conformance testing into three function modules: Syntax testing, Structure testing and Semantic testing. In the Syntax testing module, the testing method of file identifier, key word, etc, which adopts computer compile technology, combining the structure characteristic of examined file, is researched. The STEP-NC products data model and the structure level relation of AP238 processing procedure are described, and the mapping from EXPRESS language data structure to Python language is built up. The topological data list is set up by utilizing data dictionary which saves level relation of data of STEP-NC, and the information extraction of AP238 file is realized. The tool path is approximately divided into parallel axial (or radial) and along profile according to the machining_feature, machining_operation and machining_strategy that are defined in STEP-NC. Two algorithms of tool path are developed in the thesis and the automatic generation of the tool path based on the machining_feature of the STEP-NC turning is fulfilled. Finally, the system structure of turning NC system based on STEP-NC is researched. After analyzing the compiler function module of STEP-NC turning NC system, the realization of the compiler is brought out. Base on above research, the development foundation of STEP-NC turning NC systems software platform is established.