CNC Technology STEP-NC (below)

The program itself also adopts the file format specified in ISO-10303, which can be divided into two parts: the header and the data segment. The file header is marked with "HEADER", which mainly describes the file name, programmer, date, and comments. The data segment starts with "DATA" and contains all the information and operational tasks required to process the part. According to the regulations, it first needs a PROJECT statement, and the following content can be divided into three parts: the work plan and executable statements (Executable, including work steps, general NC functions such as information display, and process control), and technical description ( Tool, machine tool functions, machining strategies, etc.), geometric descriptions (geometric data, machining features, etc.).
STEP-NC provides the development space for the CNC. The development of STEP-NC has allowed the STEP standard to be extended to the bottom layer of automated processing equipment and has established an expressway for the entire manufacturing network. It can be foreseen that in the future, the CNC system will undergo fundamental changes in structure, function, and status in the manufacturing system. At the same time, this change will inevitably affect related CAX technologies (such as CAD, CAPP, CAM, CAE, and PED). The development of ERP, etc.), tools, machine tools, and fixtures, as well as the facts of advanced production models. As far as the current research results are concerned, the more direct effects that can be foreseen are mainly the following:
1. CNC programming interface: replacing ISO-6983 with ISO-14649 makes the programming interface greatly improved, on-site programming is convenient and replaces easy to reuse. When some features of the machined workpiece are slightly changed, only the geometric description of the relevant feature needs to be changed, and other elements do not need to be changed. In addition, the unified program can be run directly on different types of machine tools.
2. The openness of the CNC system: At present, due to the narrow coverage of ISO-6983, CNC manufacturers have to develop their own expansion instructions. So CAM and CNC must use the same set of code, otherwise they must use a specific post-processing program. For the STEP-NC controller, the data format (AP-238) is exactly the same. He tells the CNC “what to process” rather than the specific action, so no post-processing program is required. The specific action is determined by the CNC. The program has Good interoperability and portability.
3. The intelligentization of CNC system: As the current interface between CAM and CNC, the formation process of G and M code has caused the loss of a large amount of useful information, which is also one of the main reasons for the current low level of CNC intelligence. In contrast, the STEP-NC CNC contains all the information required for processing the product, providing the basic conditions for the CNC system to perform autonomous processing based on a thorough understanding of the product.
4. Repartitioning of functions between CMA/CNC: The CNC knows more about the operation of the machine than the CAM or CAPP system, and the specific process processing (such as the selection of tools, compensation, and the determination of the route of travel) performed within the CNC is more likely. Get the best processing results. Therefore, the future CNC will complete some of the functions of the CAM system, and on this basis may be installed by the embedded CAM system, directly based on the CAD data model for processing.
5. Processing quality and efficiency: STEP-NC's proposal changes the position of the current CNC system as a passive executor of machining tasks. The enhancement of CNC functions can also improve the efficiency of its upstream links. STEP Tools's research shows that the application of STEP and STEP-NC can reduce the preparation of production data in the CAD stage by 75%, the process planning (CAM) time by 35%, and the processing time (CNC 5-axis high-speed milling) by 50%.
6. Data sharing and network manufacturing: The development of STEP-NC has enabled a two-way seamless connection between a STEP-NC-based CNC system and all STEP-based CAX systems (for example, CAD systems can read STEP-NC data directly from a CNC system. The geometric information) creates conditions for web-based manufacturing models and technologies.