Feature Modeling And Research Of Process Planning System Based On STEP-NC

With the gradual perfection of STEP-NC in CNC machine interface standards, CNC technology will be developed rapidly, which becomes one hotspot of the current researches at home and aboard. Euramerican developed industrial countries have already invested massive resources in this field and obtained certain results. Although China has started the study of NC technology and accesses to certain success since the end of 1970s, there is still a big gap between our country and the international advanced NC technology.This article started with familiarizing with the standards of STEP and STEP-NC.A feature-based modeling and process design system which could make the realistic and reasonable evaluation mechanism and the overall plan from a technical perspective was established based on STEP-NC with the principle and methodology of STEP standard,which would provide a certain significance for CIMS.In order to achieve automatic generation and the technics information design of the manufacture features, ISO14649 and AP238 application protocol were studied and the standards of STEP and STEP-NC were analyzed while definitions of the substantiality in EXPRESS and the relationship and heritage between the substantiality and EXPRESS were mastered,and the data(such as manufacturing features and process information ) description in the standard of STEP-NC was familiared,too.According to the definition of manufacturing features in the ISO14649-10 standard, a customized feature library was built used in UG with User Defined Feature.The features were established by transferring feature model directly from the feature libraries and inputting feature dimension parameters according to parts specifications in the design of parts,which layed the foundation for process planning for the various features of parts by the process design system based on STEP-NC. According to STEP-NC standard, the feature dimension information for each feature in the parts having been designed was extracted and the design on the process parameters was carried out in the feature modeling system based on STEP - NC.And the the feature dimensions information and process information was stored in STEP-NC database, which provided data support for the generation of STEP-NC files.A feature modeling and process design system was established based on STEP-NC in the integration environment of UG 6.0, VC# 2005 and Access2003, which achieved the transfer of related parts from feature libraries and inputted the process information into a database by interactive inputting.