Abstract:

Manufacture feature reconstruction is a key technology in STEP-NC machining program extraction. First of all, entities in STEP-NC data model were coded, then raw node data and dictionary entity data were constructed. Node-entity data was constructed by matching node data and dictionary entity data. According to the geometry, entity was divided into five classes, there were feature, profile, curve, point and placement. In the course of reconstruction, node’s attribute content construction in upper class was completed by its entity reconstruction function in lower class. In the same class, node’s geometry was constructed from above to below according to inherit relationship between entities. In such a way, a test prototype was developed and verified by program in STEP-NC FDIS, and the reconstructive mechanism is proved by the result.

Key words: STEP-NC, manufacture feature, reconstructive mechanism, dictionary entity

摘要：

制造特征的重构是STEP-NC加工程序信息提取的关键技术之一。分别创建了原始节点数据和字典实体数据，并对STEP-NC模型中的实体进行编码。匹配原始节点数据和字典实体数据，构造节点-实体关联数据，利用节点-实体关联数据重构特征的三维实体表示数据，根据几何层次关系，分别把几何信息分为特征、面、线、点和定位层五层。在重构过程中，上一层实体的节点的属性内容重构调用下一层所对应实体的重构函数；在同一层中，利用字典实体间的继承关系，以编码匹配的方式，自上而下地重构节点几何模型。根据上述模型，开发了实验原型系统，并用STEP-NC标准草案中的示例程序给出重构结果，验证了本模型的有效性。

关键词: STEP-NC, 制造特征, 重构机制, 字典实体