Research On Data Modeling Of Screw Whirling And NC Programming Based On STEP-NC

Special-shaped screws have become an important component of industrial equipment, which are widely used in petroleum, building materials, metallurgy, shipbuilding and other industries and play a crucial role in the productivity, precision, and even the whole performance of these machines. Whirling proves to be an efficient method of processing screws. During this whirling, the quite long contact line between cutters and workpiece keeps the processing steadily. And it has high efficiency in material removal and good quality in screw surface.The progress in STEP-NC has provided very much room for the development of NC machining technologies. Up to date, the STEP-NC date model is still limited to general characteristics definition, general milling and turning processes, without covering the whirling of screws. In this paper, STEP-NC modeling of screw and whirling are proposed, and methods of generating screw STEP-NC program are presented.This study investigates NC programming based on the STEP-NC and the whirling of screw. The paper starts with the standards of STEP and STEP-NC, describing the related knowledge of STEP and STEP-NC. Then, the programming system framework is built which generates STEP-NC program from screw STEP file automatically. The later chapters are studied mainly for the realization of the NC programming system. Firstly, the STEP modeling of screw is researched; The representation of helical surfaces in STEP is analyzed, and the mathematical model of helical surfaces is also built. On the basis of the existing STEP-NC standard, the date model of screw and whirling are defined, which extend the STEP-NC to the screw whirling filed. Then, the key technologies involved in the programming system are researched, including feature recognition of screw and the generation method of STEP-NC. During the feature recognition, the extraction method of the geometric information and parameter calculation are investigated. During the generation method of STEP-NC, the method of generating head segment and data segment are presented.Finally, a programming system interface to generate STEP-NC program of screw based on C# platform is developed on the basis of the above theory and technology. And a case study is presented, which proves the feasibility of the above theoretical research.