Study On Automatic Graphic Feature Oriented NC Programming

This thesis deals with the technology of automatic NC programming based on graphic feature principle. The purpose to study in this thesis is to reduce the programming difficulty, avoid low efficiency and time consuming in reading the drawings manually, promote the NC programming efficiency, and raise the productivity. Through analyzing of the existing NC programming system, an automatic programming system of NC blanking process for panels is developed, which is adopted the technology of 2D drawings feature recognition and automatic NC programming, combining the characteristic of NC blanking process for panels. The system is useful to solve the design and the manufacturing process automation, realize the integration of CAD/CAM system .At the beginning of the thesis, it describes the automatic NC programming, analyzes the modern condition and future developing direction of the automatic NC programming.The development and main method of the feature recognition for 2D drawings are investigated. Furthermore, the feature recognition for 2D drawings is brought into the automatic NC programming system; After analyzing structure and format of the DXF file in detail, the thesis uses the DXF file to input the data for system; combining the characteristic of blanking process for panels, a method of feature recognition of 2D Drawings of panels is presented, which is on the basis of the outline information in a graphic. The method can recognize and extract the feature information from the 2D design drawing of the panel's part.And then, fully utilizing the result of feature recognition and extraction of 2D drawings, system can automatic to choose the process cutters, optimize the selection of the machining route of the cutters, perform postprocess, and finally accomplish the NC file through automatic programming; Through the study of the greedy method of traveling salesman problem in Graph Theory, an improved greedy method is proposed. The method optimizes the selection of the machining route of the cutters effectively, which promotes the speed of NC process. It is significant for large-scale production.According to above-mentioned research, an automatic NC programming system named as "CAD/CAM Continuum System" is developed. The system is a software project of Dalian Hi-Think Computer Technology Co., Ltd (DHC) for Japanese. At present, the system has already been verified tentatively through consumers. The testing results indicate that the function and performance of developed achieve the predefined specification.