Abstract: Since the 1990s, the structure of CNC systems has shifted from closed to open. The hardware structure of CNC systems has become more standardized, with more hardware becoming interchangeable; the software structure has become more modular and transparent; the functions of CNC systems have become more intelligent; and CNC systems are increasingly connected to other control systems via networks to achieve remote control and remote maintenance services. Open, intelligent, and networked CNC technology is the foundational technology for realizing manufacturing automation, intelligence, integration, and globalization. Keywords: CNC system, open, intelligent, network, globalization. CNC technology is a technology that uses digital information to control mechanical motion and working processes. The application of CNC technology has not only brought revolutionary changes to traditional manufacturing, making manufacturing a symbol of industrialization, but also, with the continuous development of CNC technology and the expansion of its application fields, it plays an increasingly important role in the development of some important industries related to national economy and people's livelihood (IT, automobile, light industry, medical, etc.). This is because the digitalization of equipment required by these industries is a major trend in modern development. From the current development trend of CNC technology in the world, its main research hotspots are as follows: 1. High speed, high efficiency, high precision, and high reliability. 2. Rapid development of 5-axis linkage machining and composite machining. 3. Intelligentization, openness, and networking have become the main trends in the development of contemporary CNC systems. 4. The emergence of a new generation of CNC machining processes and equipment, such as FMC, FMS, CIMS, Web-based manufacturing, and drawing-free manufacturing technologies. In the 1990s, foreign CNC systems completed the transformation from 16-bit to 32-bit machines and from DC to AC fully digital servo drives. The CNC system architecture shifted from closed to open, allowing CNC systems to fully utilize the abundant resources of computer technology and quickly and flexibly replace hardware and software according to the requirements of the controlled object. It also enabled timely absorption of new technologies, accelerating the pace of CNC technology development and shortening the development cycle. This paper will discuss open, intelligent, and networked CNC systems, outlining their basic concepts, architecture, and development trends. 1. Basic Concepts of Open, Intelligent, and Networked CNC Technology The essence of an open CNC system is that the development of CNC systems can be carried out on a unified operating platform, targeting machine tool manufacturers and end users, forming a series. It can also integrate users' specific applications into the control system. To achieve open CNC systems of different varieties and grades. The IEEE definition of an open system is: an open system can effectively run on different platforms, interoperate with other application systems, and provide a unified style of interaction with users. This is known as interoperability, portability, scalability, and interchangeability. With the development of computer hardware and software technology, the latest specific views on open systems include: 1.1 Both the hardware and software of an open control system should be flexible, allowing changes to the basic hardware configuration, and the software can be changed at all control levels. 1.2 The hardware and software of an open architecture system must be truly "plug and play." If a product must be "recalled" to install new hardware and software, it is not truly open. 1.3 The controller must be standardized to allow third parties to participate in the development of new hardware and software. 1.4 An open system allows third-party software to be added as components of the system. That is, it is a standard system on which the system can integrate with other components at the component level and share data. 1.5 An open control system can work collaboratively with other systems at the system level. Intelligent CNC systems refer to systems with anthropomorphic intelligent characteristics. They possess knowledge processing activities that simulate, extend, and expand intelligent behaviors within the CNC system, such as self-learning, self-adaptation, self-organization, self-optimization, self-stabilization, self-identification, self-planning, self-repair, and self-replication. Intelligent CNC systems detect, model, and extract features from physical quantities affecting machining accuracy and efficiency. They automatically perceive the internal state and external environment of the machining system, quickly making intelligent decisions to achieve optimal goals. They perform real-time control of process parameters such as feed rate, depth of cut, coordinate movement, and spindle speed, ensuring the machine tool's machining process is in its optimal state. The functions required by current CNC systems go beyond just high performance (high speed, high precision, high reliability). They also include many intelligent functions, such as machining motion planning, reasoning, decision-making capabilities, machining environment perception, manufacturing network communication capabilities (including human interaction), intelligent programming, intelligent databases, and intelligent monitoring. Practice has proven that the aforementioned "intelligent" technologies will be applied to all aspects of the adjustment, use, and maintenance of next-generation CNC machine tools in the 21st century, greatly simplifying manual intervention. The application of "intelligent" technologies should be used to enhance the human-machine interface, fully utilizing natural language, graphical interfaces, and simplified manual operations to make machine tool adjustment, use, and maintenance increasingly "foolproof." Networked CNC connects manufacturing units and control components via networks or the Internet/Intranet, or shares resources required for the manufacturing process (such as machining programs, machine tools, tools, and monitoring instruments). Networking includes two aspects: internal networks (fieldbus networks) and external networks. 1.5.1 Internal Network The internal network refers to the connection between CNC units and servo drive and I/O logic control units within the CNC system via a fieldbus network. For CNC system hardware, openness mainly refers to the fact that its computer, network, servo system, and I/O logic control units should have a unified interconnection standard to achieve interchangeability. To ensure the interchangeability of CNC system hardware... Currently, European CNC manufacturers widely use SERCOS (Serial Real-time Communication System, a network interface protocol suitable for high-speed servo control, which became the IEC 1491 international standard in 1995) fieldbus as the interface with digital drive units, and Pmfibus fieldbus as the interface with VO logic control units. 1.5.2 External Network The external network refers to the network connection between the CNC system and other control systems or external host computers. Through the network, remote control and unmanned operation of equipment, remote machining program transmission, remote diagnosis and remote maintenance services, and technical services can be achieved, thereby improving machine tool productivity. The network production management system monitors the production site at any time through the enterprise intranet to perform optimal planning and scheduling; the operator skill database digitizes the skills formed by rich experience and intuition, continuously accumulates and shares them with the whole company, achieving efficient and high-quality machining, and creating new processes, new knowledge and new know-how; the new CAD/CAM system can immediately convert CAD data into machining programs, tool lists, process cards and machining process drawings, realizing concurrent engineering to shorten the production cycle. Furthermore, by connecting to the outside world via the Internet, a window can be established for each customer, allowing for rapid response to customer requirements. In conditions of high-variety, low-batch production, networking machine tools can improve cutting time from 25% to 65%. Remote diagnostic products allow easy operation of machine tools located in the workshop from a personal computer. This includes editing and modifying part programs and PLC programs, monitoring the current status of each axis, and transferring files. It is not only used for diagnosing CNC systems after a fault occurs but also for regular preventative diagnostics by users. 2. Basic Structure of an Open, Intelligent, Networked CNC Platform An open, intelligent, networked CNC system platform consists of system hardware and system software. The system software includes a real-time operating system, communication system, device drivers, and other optional system programs, such as database systems and graphics systems. The system software uses a standard application programming interface (API), meaning the interface and the object can be consistent. Alternatively, it can be separated from the operating system through device drivers. The system hardware is interconnected via an information management network and open device-level networks to transmit commands and data, completing CNC tasks in parallel. For CNC system hardware, openness primarily refers to the need for unified standards in its computer, network, servo system, and I/O logic control units to achieve interchangeability. To ensure hardware interchangeability, all CNC system manufacturers worldwide agree that fieldbus technology should be adopted. 3. Application of Open, Intelligent, and Networked CNC Systems In recent years, my country has developed a number of CNC systems, such as the Huazhong I, Aerospace I, Zhonghua I, and Lantian I. The Huazhong I, using a general-purpose industrial microcomputer as its hardware platform, features a modular, open architecture and has reached international advanced levels. It has won the second prize of the National Science and Technology Progress Award and the first prize of the National Education Commission Science and Technology Progress Award, making it the highest-level domestically produced CNC system to date to receive a national award. The open CNC system software and hardware platform has been successfully developed on DOS and Linux operating system platforms. It has been used to develop lathes, milling machines, machining centers, contour mills, roll mills, and hobbing mills. The Huazhong CNC system is used in over 30 product categories, including broach grinders, tool grinders, camshaft grinders, non-circular gear sector gear shapers, rack gear shapers, spiral bevel gear milling machines, boring machines, laser processing, glass machinery, textile machinery, and medical machinery. This demonstrates the excellent openness and secondary development capabilities of Huazhong CNC systems. With years of continuous support from the National 863 Program and key technology research programs, my country has basically mastered the fundamental technologies of networked and digital manufacturing systems. For example, at the 1999 International Machine Tool Exhibition held in Beijing, Wuhan Huazhong CNC Co., Ltd. pioneered the launch of a networked CNC system. The prototype machine enabled remote operation and control of remote CNC machine tools via Internet. At the expo, Beijing University of Aeronautics and Astronautics, in collaboration with the Beijing Institute of Mechanical and Electrical Engineering, showcased an open CNC system based on PC computers and fiber optic digital communication servo technology (SERCOS). This system simultaneously controlled 50 servo axes and spindles on 1-8 machine tools via fiber optics, forming a flexible production line demonstration system that received high praise from the domestic machine tool industry. At the 2001 Beijing International Machine Tool Expo, Huazhong CNC, in collaboration with Beijing No. 1 Machine Tool Plant, demonstrated remote fault diagnosis technology based on Internet; and in collaboration with Guilin Machine Tool Co., Ltd., showcased remote control technology consisting of four networked machine tools. These achievements laid a solid foundation for the research and development of CNC systems in a network environment. For example, Huazhong CNC, at Jiangsu Changchai Co., Ltd., networked five machining centers and one contouring CNC machine tool in its mold-making workshop, enabling remote design and programming, and then transmitting and sharing part machining programs via the Internet. This achieved network integration of CAD/CAM/CNC, greatly improving production efficiency and equipment utilization. The mold workshop at Changchai Co., Ltd.'s North Plant has four CNC machine tools equipped with the Huazhong Network CNC System, all connected via an internal local area network (NT network). The server on the NT network in the mold workshop is connected to the Changchai main plant's computing center, 5 km away, via the Internet. CNC programs generated by UGII or other CAD/CAM software from the main plant's computing center can be transmitted to the control system of any CNC machine tool via the Internet and the server. Because the Huazhong Network CNC has ample memory and external storage space, its resources can be shared on the computer network. Therefore, the CNC programs on each Huazhong CNC system's memory can be shared with any other Huazhong CNC system via the network. This allows CNC machining programs generated by digital contouring measurement to be shared on other non-contouring CNC machine tools for mold processing. Due to the extremely fast data transmission speed of the computer local area network (approximately 10.100MB/s or more, while the DNC interface speed is approximately 9.6kB/s), the transmission speed for large-capacity programs for complex molds is very fast and reliable. With the continuous penetration and development of artificial intelligence in the computer field, CNC systems are evolving towards intelligence. In the new generation of CNC systems and servo drives, performance has been greatly improved due to the adoption of three new control mechanisms: "evolutionary computation," "fuzzy system," and "neural network." This high-performance, intelligent CNC system not only possesses functions such as automatic programming, feedforward control, adaptive cutting, self-generation of process parameters, and dynamic compensation of motion parameters, but also features a highly user-friendly human-machine interface that takes into account operational factors. Currently, CNC systems using fuzzy control principles and high-performance CNC machine tool servo drives with self-learning, self-establishment of mathematical models, and self-adjustment of parameters are already available and highly competitive in the market. Open, intelligent, and networked CNC systems have the following practical application needs in my country: 3.1 Network Manufacturing, Global Manufacturing: Under the new manufacturing model, the CNC system's internet access enables future manufacturing enterprises to publish their manufacturing capabilities or allow external parties to understand them during dynamic alliances and manufacturing system restructuring. This can even lead to the formation of online virtual workshops (T/T) and e-commerce, realizing network manufacturing of remote CAD/CAM/CNC systems. 3.2 Large-Capacity Storage Resource Sharing: Most existing CNC systems in my country have limited memory, lack network functionality (only low-speed DNC interfaces), and lack large-capacity storage devices (such as hard drives). However, the processing volume of complex molds is very large, typically measured in 1MB units. Applying a network CNC system can meet the requirements for large-capacity information communication and exchange between CAD/CAM and CNC systems on a high-speed local area network. 3.3 Remote Monitoring and Diagnosis: When a CNC system malfunctions, the CNC system manufacturer can quickly diagnose and maintain the user's CNC system via the internet, greatly reducing the blind spots in maintenance and improving equipment availability. This meets the user's requirements for remote fault monitoring, fault diagnosis, and fault repair of CNC machine tools. 3.4 Remote Operation and Remote Training: By sharing CNC machine tools on a network, similar to a shared printer in an office network, this meets the requirements of some manufacturing industries for remote operation of processing equipment (such as the shaping process after rocket engine propellant loading) and remote training. 3.5 New Generation Intelligent CNC Systems: Developing and researching a new generation of intelligent computer-based CNC systems and corresponding intelligent programming systems suitable for turning, milling, machining centers, EDM, and other intelligent machining processes. This includes researching and formulating hardware and software specifications for intelligent CNC systems and implementing them in major CNC production bases; developing two general-purpose systems (turning and machining centers) and three application systems (turning centers, five-sided machining centers, and intelligent EDM); and intelligent programming systems, etc. 3.6 New Generation Spindles and Servo Drives: Developing and researching high-performance servo drive devices and corresponding motors, including applications in self-learning, self-adjusting parameter, fully digital, linear motors, and low-cost drive devices. 4. Conclusion Open, intelligent, and networked CNC systems can significantly improve the level of CNC technology and industrialization in China: 4.1 The adoption of a unified hardware and software platform ensures continuous and sustainable technological development. 4.2 Domestic CNC system developers and manufacturers do not need to repeatedly invest excessive equipment and funds in the development and production of basic hardware and software components. They can concentrate their efforts on developing their areas of expertise, competing with large foreign companies with the overall development capabilities of the domestic market. This can significantly improve the competitiveness of domestically produced CNC systems. 4.3 Major domestic CNC manufacturers use the same basic hardware, which can increase hardware production volume. Appropriately scaled production can significantly reduce the cost of CNC systems, improve product quality, and enhance product consistency. 4.4 Open, intelligent, and networked CNC systems facilitate production management and can improve the productivity of CNC machine tools. 4.5 After-sales service is easier to conduct for standardized open, intelligent, and networked CNC systems. Fully recognizing the urgency of developing open, intelligent, and networked CNC technologies, developing CNC systems with independent Chinese versions, and conducting demonstration applications are of great significance for promoting the development of my country's next-generation CNC systems, improving the comprehensive competitiveness of domestically produced CNC systems in the market, and laying the foundation for the large-scale production of CNC systems.