中文摘要：

基于STEP-NC应用数据模型和标准数据存储界面（SDAI），通过构造数据字典模型、实体实例数据结构模型和零件实例数据结构模型，建立了描述STEP-NC加工程序的零件一实体分级数据结构，实现了STEP—NC数据到C＋＋数据的转换．采用步进式构造方式提取STEP—NC程序信息，通过回溯递归方法构造了STEP-NC单元实体实例，进而匹配实体属性项内容，建立了零件级的数据结构．该方法避免了SDAI迟联编在实体建立和实体实例建立之间的时序矛盾．最后开发了信息提取原型系统，实例论证表明，该系统能够识别STEP—NC数控加工程序，并显示零件单特征几何形体．

英文摘要：

Based on standard for the exchange of product model data-numerical controllers （STEP-NC） and standard data access interface （SDAI）, a two-level part-entity data structure was constructed to transform STEP-NC data to C＋ ＋ data. And data dictionary model, entity instance data structure model and part instance data structure model were also described. In the course of information extracting, data were constructed in a step-by-step manner. The cell entity instance was constructed by backtrack recursive procedure, then the entity attribute content was matched, finally the part-level data structure was constructed. This process avoids the conflict between entity constructing and entity instance constructing in SDAI later binding. In such way, a STEP-NC information extracting prototype system was developed. By inputting ISO14649 example data, the information were extracted and the part was also displayed.