With the gradual establishment and improvement of the global free trade system and the formation of the world's major markets, international economic and trade exchanges and cooperation have become more and more frequent and frequent. This has led the manufacturing industry to move toward international cooperation and promote networked manufacturing. Increasingly. In the networked manufacturing model, when customers place product orders, the alliance members with different geographic distributions form a dynamic alliance, using their own superior technologies and equipment, and the division of labor and collaboration for production design. Network-based global manufacturing based on Internet/Intranet has become the development trend of future manufacturing systems.
Second, the status of networked NC technology at home and abroad
1. The development of open architecture
2. Networking of CNC system
Third, the development of CNC system
The first stage is the NC (Logical Digital Control) stage. During this stage, the development of the CNC system has gone through three eras: the era of electron tubes, the era of transistors, and the age of small and medium-scale integrated circuits.
The second stage: CNC (computer digital logic control) stage, this is the fourth generation of numerical control system; from 1974 microprocessors began to be used in numerical control systems, CNC system developed to the fifth generation, after several years of development, CNC The system has been fundamentally improved from performance to reliability. From the late 1970s to the entire 1980s, CNC technology was developed and applied on a large scale throughout the world. Actually, by the end of the 20th century to date, Most of the CNC systems used in production are fifth-generation CNC systems. Since the 1990s, the development speed of microelectronics and computer technology has grown by leaps and bounds. The development of personal computers, that is, PCs, has become particularly prominent. The progress in software, hardware, and peripheral devices is changing with each passing day, and the degree of integration of chips used in computers is increasing. High, more powerful, and more and more low-cost, the functions that could be realized on large and medium-sized machines can now be realized on microcomputers. In the United States, the so-called CNC system developed on the PC platform first appeared. That is, the PC numerical control system, which is what we now say the sixth generation of numerical control system.
Fourth, the development trend of numerical control technology
1. Functional development direction
(l) Graphical user interface
The user interface is the dialogue interface between the numerical control system and the user. Because different users have different requirements for the interface, the workload for developing the user interface is enormous, and the user interface becomes one of the most difficult parts in the development of computer software. Current NTERNET, virtual reality, scientific computing visualization and multimedia technologies also impose higher requirements on the user interface. The flexible user interface greatly facilitates the use of non-professional users. People can operate through windows and menus, facilitating blueprint programming and rapid programming, three-dimensional color stereoscopic dynamic graphic display, graphic simulation, graphic dynamic tracking and simulation, views in different directions, and Partial display scaling function implementation.
(2) Scientific Computing Visualization
Scientific computing visualization can be used to efficiently process data and interpret data, so that information exchange is no longer limited to text and language, but can use graphics, images, animations and other visual information directly. The combination of visualization technology and virtual environment technology has further broadened the application fields, such as no drawing design, virtual prototype technology, etc. This is of great significance to shorten the product design cycle, improve product quality, and reduce product cost. In the field of numerical control technology, visualization technology can be used for CAD/CAM, such as automatic programming design, automatic parameter setting, tool compensation and tool management data dynamic processing and display, and visual simulation demonstration of machining processes.
(3) Diversification of interpolation and compensation methods
Various interpolation methods such as linear interpolation, circular interpolation, cylindrical interpolation, space elliptic surface interpolation, thread interpolation, polar coordinate interpolation, 2D + 2 helical interpolation, NANO interpolation, NURBS interpolation (non- Uniform rational B-spline interpolation, spline interpolation (A, B, C spline), polynomial interpolation, etc. Multiple compensation functions such as backlash compensation, verticality compensation, quadrant error compensation, pitch and measurement system error compensation, speed-dependent feedforward compensation, temperature compensation, tool radius compensation with smooth approach and exit, and opposite point calculation.
(4) Built-in high-performance PLC
The CNC system is equipped with a high-performance PLC control module that can be programmed directly in ladder diagrams or high-level languages, with intuitive online debugging and online help functions. The programming tool contains an example of a standard PLC user program for a lathe milling machine. The user can make edits and modifications on the basis of a standard PLC user program to easily create his own application program.
(5) Multimedia Technology Applications
Multimedia technology integrates computer, audiovisual and communication technologies to enable computers to have the ability to comprehensively process sound, text, images and video information. In the field of numerical control technology, the application of multimedia technology can be integrated and intelligent information processing, and has great application value in the real-time monitoring system and production field equipment fault diagnosis, production process parameter monitoring and so on.
2. Development direction of structural system
(l) Modularization, Specialization, and Personalization In order to adapt to the features of many varieties and small batches of CNC machine tools, the machine tool structure is modular and the CNC functions are specialized. The performance-to-price ratio of machine tools is significantly improved and the optimization is accelerated. Hardware modularization facilitates the integration and standardization of CNC systems. According to different functional requirements, the basic modules, such as CPU, memory, position servo, PLC, input and output interfaces, and communication modules, are made into standardized serialized products, and the function cutting and the number of modules are increased and decreased by the way of building blocks to form different types. Grade CNC system. Personalization is a particularly noticeable development trend in recent years.
(2) Openness adopts general-purpose computers to form bus, modular, open, and embedded architectures, which are easy to cut, expand, and upgrade. They can form numerical control systems of different grades, different types, and different degrees of integration. Open general-purpose real-time dynamic full-closed-loop control mode is adopted during processing, which makes it easy to integrate computer real-time intelligent technology, network technology, multimedia technology, CAD/CAM, servo control, adaptive control, dynamic data management, dynamic tool compensation, dynamic simulation, etc. The combination of high technology and new technology constitutes a close-loop closed-loop control system for the manufacturing process, so as to achieve integration, intelligence, and networking. Based on the characteristics of openness, low cost, high reliability, and rich hardware and software resources of the sixth generation of PC-based development, more CNC system manufacturers will embark on this path. At least PCs are used as front-end machines to handle human-machine interfaces, programming, and networking communications. The original system assumes the task of CNC, and the friendly man-machine interface of the PC will be popularized to all CNC systems, remote communication, etc. Remote diagnosis and maintenance will become more common. Japan, the European Union, and the United States are conducting open and front-end standards research on open-end CNCs.
Network CNC Technology Overview
I. Introduction