Research On NC Programming Technology Based On STEP-NC Standards

STEP-NC (ISO 14649),the data model standard of the computerized numerical control was constituted by ISO/TC184/SC1. STEP-NC is an extension of STEP that organizes manufacturing operations into"working steps."Each step defines an operation that can be performed on a CNC machine tool. The working steps defined by STEP-NC are roughly equivalent to the machining commands represented by traditional G codes. However, unlike G codes, the working steps are linked to three-dimensional geometry, tool requirements and feature definitions so that the machine tool can dynamically plan an operation using the available resources and intelligently re-plan an operation when necessary.The develop course of product data exchange has been analyzed firstly, especially the evolution of NC programming technology and NC system. After the analysis of the disadvantages of ISO6983, this article brought the concept of STEP-NC,which is the new standard of numeric control. The main features, the contents and structure, file formats and the direction of development of STEP are summarized. All data types defined in the description language EXPRESS of STEP-NC are summed up. And then, the main features, the contents and structure, file formats and the direction of development of STEP-NC are summarized respectively. The contents of ISO14649 are given too. Then functional architecture of STEP-NC translaters is analyzed.This topic adopted Visual C++ as the developing tool, and fully exertive the programming function of C++ and the function of sketch showing, to realize the translationg of STEP-NC files to G codes. The procedure is divided into four parts, collecting information and identifying features, generating tool travel-paths and G codes. Also, through the programming technology of MFC, the STEP-NC files and G codes can be seen in the interface. Finally, the feasibility of the STEP-NC translator was examined, and the codes were simulated through CAXA-ME software.