INTERPRETING MODULE AND COORDINATE PROBLEM FOR CNC BASED ON STEP-NC INTERFACE

ZHU Xiaoming WANG Yongzhang FU Hongya

(School of Mechanical and Electrical Engineering, Harbin Institute of Technology, Harbin 150001 )

Abstract: Aiming at the data model and programming character of object oriented of STEP-NC, with design thinking of software module applied, an interpreting module including four sub-modules is built. ① Inputting sub-module is responsible for parsing STEP-NC program, and a special data structure is designed to store the entity information of program line. ② Recognizing sub-module can recognize all kinds of entities in the machining program, and a fixed recognizing order is pro-posed to guarantee the accurate result. ③ Modeling sub-module establishes corresponding C++ class model by entity mapping according to entity type. ④ Planning sub-module plans the tool path according to the class model parameters, and its running process is explained. A complicated problem involved in path planning is coordinate transformation. The hierarchy frame of coordinate of STEP-NC is summarized and the coordinate reference principle is elaborated. By visual tool path in a simulation system for 3-D milling machining based on STEP-NC, the path planning is proved to be right. At last the interpreting module is planted into an open CNC and confirmed to be valid and correct by real machining experiment.

Key words: STEP-NC Interpreting module Path planning Coordinate system

CLC No: TH166

2005年黑龙江省重点科技攻关资助项目(GB05A501). Received 20060227,  received in revised form 20060816