At present, the world's advanced manufacturing technology continues to rise, the application of ultra-high-speed cutting, ultra-precision machining and other technologies, the rapid development of flexible manufacturing systems and the continuous maturity of computer integrated systems, which puts forward higher requirements for CNC machining technology. Today's CNC machine tools are developing in the following directions.
1. High speed, high precision speed and accuracy are two important indicators of CNC machine tools, which are directly related to processing efficiency and product quality. At present, the numerical control system uses a processor with higher number of bits and frequency to improve the basic computing speed of the system. At the same time, ultra-large-scale integrated circuits and multi-microprocessor structures are adopted to improve the data processing capacity of the system, that is, to improve the speed and accuracy of interpolation operations. And the linear servo feed mode of the linear motor directly drives the machine tool table, and its high speed and dynamic response characteristics are quite superior. The feed-forward control technology is adopted to greatly reduce the tracking hysteresis error, thereby improving the machining accuracy of corner cutting.
In order to adapt to the requirements of ultra-high-speed machining, CNC machine tools adopt the structural form of spindle motor and machine tool spindle in one, realize the integration of frequency conversion motor and machine tool spindle, and the bearing of the spindle motor adopts magnetic bearing, liquid dynamic and static bearing or ceramic rolling bearing. At present, ceramic tools and diamond-coated tools have begun to be applied.
2. Multi-function equipped with automatic tool changing mechanism (tool magazine capacity up to 100 or more) of various machining centers, can simultaneously realize milling, boring, drilling, turning, reaming, reaming, tapping threads and other processes on the same machine tool, modern CNC machine tools also use multi-spindle, multi-patch cutting, that is, different parts of a part at the same time in different ways of cutting. Due to the multi-CPU structure and hierarchical interrupt control mode, the numerical control system can simultaneously carry out parts processing and programming on one machine tool to achieve the so-called "front-end processing and background editing". In order to adapt to the requirements of flexible manufacturing systems and computer integrated systems, the CNC system has a long-distance serial interface, and can even be networked to realize data communication between CNC machine tools, and can also directly control multiple CNC machine tools.
3. Intelligent modern CNC machine tools will introduce adaptive control technology, according to the change of cutting conditions, automatically adjust the working parameters, so that the processing process can maintain the working state, so as to obtain high machining accuracy and small surface roughness, but also improve the service life of the tool and the production efficiency of the equipment. With self-diagnosis and self-repair function, in the whole working state, the system can carry out self-diagnosis and inspection of the CNC system itself and various equipment connected to it at any time. Once a fault occurs, measures such as shutdown are immediately adopted, and fault alarms are carried out to prompt the location and cause of the failure. It is also possible to automatically take the failed module offline and turn on the standby module to ensure the requirements of an unmanned working environment. In order to achieve higher fault diagnosis requirements, the development trend is to adopt artificial intelligence expert diagnosis systems.
4. CNC programming automation With the development of computer application technology, CAD/CAM graphic interactive automatic programming has been widely used, which is a new trend in the development of CNC technology. It is the use of CAD drawn part processing drawing, and then through the computer tool trajectory data for calculation and post-processing, so as to automatically generate NC part processing program to achieve CAD and CAM integration. With the development of CIMS technology, there is a fully automatic programming method of CAD/CAPP/CAM integration, which is the biggest difference with CAD/CAM system programming is that the processing process parameters required for its programming do not have to be manually involved, and are obtained directly from the CAPP database in the system.
5. Reliability maximization The reliability of CNC machine tools has always been the main indicator that users are most concerned about. The numerical control system will use more integrated circuit chips, using large-scale or ultra-large-scale dedicated and hybrid integrated circuits to reduce the number of components and improve reliability. Through the hardware function software, to adapt to the requirements of various control functions, and at the same time adopt the hardware structure of the machine tool body modularization, standardization and generalization and serialization, so that not only improve the hardware production batch, but also facilitate the organization of production and quality control. It also realizes fault diagnosis and alarm for hardware, software and various external devices in the system by automatically running a variety of diagnostic programs such as startup diagnosis, online diagnosis, and offline diagnosis. Use alarm prompts to troubleshoot in time; Fault-tolerant technology is used to adopt a "redundant" design for critical components to achieve fault self-recovery; Using various testing and monitoring technologies, when the production overtravel, knife loss, interference, power failure and other accidents, the corresponding protection is automatically carried out.
6. Miniaturization of control system, miniaturization of numerical control system, easy to combine mechanical and electrical devices into one. At present, ultra-large-scale integrated components, multi-layer printed circuit boards, and three-dimensional installation methods are mainly used, so that electronic components can be installed at high density and the space occupied by the system is reduced on a large scale. The use of a new color liquid crystal thin display to replace the traditional cathode ray tube will further miniaturize the CNC operating system. This makes it easy to install it on machine tool equipment and is more convenient for the operation of CNC machine tools.
