Analysis on the development trend of China's CNC m

Analysis on the development trend of China's CNC machine tool industry in 2015

in the past 20 years, with the development of science and technology, the rise and continuous maturity of advanced manufacturing technology have put forward higher requirements for CNC technology. So what is the development trend of CNC machine tool industry? The following is an analysis of the development trend of China's CNC machine tool industry in 2015:

1 Speed and precision are two important indicators of CNC machine tools, which are directly related to the quality and grade of products, the production cycle of products and the competitiveness in the market

in terms of machining accuracy, in the past 10 years, the machining accuracy of ordinary CNC machine tools has increased from 10 μ M increased to 5 μ m. Precision machining centers range from 3 to 5 μ M increased to 1~1.5 μ m. And ultra precision machining accuracy has begun to enter the nanometer level (0.001 μ m）。 The improvement of machining accuracy lies not only in the use of ball screw pairs, hydrostatic guides, linear rolling guides, magnetic levitation guides and other components, the improvement of the control accuracy of the CNC system, the application of high-resolution position detection devices, but also in the use of various error compensation technologies, such as screw pitch error compensation, tool error compensation, thermal deformation error compensation, spatial error comprehensive compensation, etc

in terms of processing speed, high-speed processing originated in the early 1990s. It is characterized by the application of electric spindle and linear motor, which greatly improves the spindle speed, with the feed speed of more than 60m/min, the feed acceleration and deceleration of more than 1~2g, and the spindle speed of more than 100000r/min. High speed feed requires that the numerical control system has fast calculation speed and short sampling period, and also requires that the numerical control system has sufficient pre-processing ability of advance path plus (minus) speed optimization (forward-looking processing). Some systems can process 5000 program segments in advance. In order to ensure the processing speed, the high-end CNC system can change the feed speed 2000~10000 times per second

2. Developing in the direction of flexibility and function integration

while improving the flexibility of single machine, CNC machine tools are developing in the direction of unit flexibility and systematization, such as the emergence of flexible and efficient processing equipment such as CNC multi axis machining centers and tool changing box changing machining centers; The bottom processing equipment composed of multiple CNC machine tools has emerged, which not only points to the flexible manufacturing cell (FMC), the flexible manufacturing system (FMS), and the flexible manufacturing line (FML)

on modern CNC machine tools, automatic tool changing device and automatic workbench exchange device have become basic devices. With the development of CNC machine tools in the direction of flexibility, function integration is more reflected in: automatic loading and unloading of workpieces, automatic positioning of workpieces, automatic tool setting, automatic measurement and compensation of workpieces, the "universal processing" integrating drilling, turning, boring, milling and grinding, and the "complete processing" integrating loading, unloading, processing and measurement

3. With the continuous penetration and development of artificial intelligence in the computer field, CNC system is developing towards intelligence. In the new generation of CNC system, due to the use of "evolutionarycomputing", "fuzzy system" and "neuralnetwork" and other control mechanisms, the performance is greatly improved. It has the functions of adaptive control of machining process, automatic load identification, self generation of process parameters, dynamic compensation of motion parameters, intelligent diagnosis, intelligent monitoring and so on

(1) due to the introduction of adaptive control technology, there are many factors affecting the machining accuracy in the actual machining process, such as uneven workpiece allowance, uneven material hardness, tool wear, workpiece deformation, machine tool thermal deformation, etc. These factors are difficult to predict in advance, so that in actual machining, it is difficult to use the best parameters for cutting. The purpose of introducing adaptive control technology is to enable the machining system to automatically adjust the cutting parameters and other parameters according to the changes of cutting conditions, so that the machining process can maintain the best working state, so as to obtain higher machining accuracy and smaller surface roughness, and also improve the service life of tools and the production efficiency of equipment

(2) fault self diagnosis and self repair function in the whole working state of the system, use the built-in program of the CNC system to carry out self diagnosis and self inspection on the CNC system itself and various equipment connected with it at any time. Once a fault occurs, take measures such as shutdown immediately, and give a fault alarm to prompt the location and cause of the fault, and use the "redundancy" technology to automatically take the fault module offline and connect the standby module

(3) automatic tool life detection and automatic tool change function use infrared, acoustic emission, laser and other detection means to detect tools and workpieces. In case of workpiece out of tolerance, tool wear and damage, alarm in time, automatic compensation or tool replacement to ensure product quality

(4) pattern recognition technology applies image recognition and voice control technology to enable the machine tool to recognize patterns and process them according to natural language commands

(5) intelligent AC servo drive technology at present, intelligent servo systems that can automatically identify loads and automatically adjust parameters have been studied, including intelligent Spindle AC drive and feed servo drive, so that the drive system can achieve the best operation

4. Developing towards high reliability

the reliability of CNC machine tools has always been the main index that users are most concerned about, which mainly depends on the reliability of each servo drive unit of the CNC system. In order to improve reliability, the following measures are mainly taken:

(1) adopt circuit chips with higher integration and large-scale or super large-scale special and hybrid integrated circuits to reduce the number of components and improve reliability

(2) through the software of hardware functions, to meet the requirements of various control functions, and through the modularization, standardization, generalization and serialization of hardware structure, to improve the production batch and quality of hardware

(3) enhance the functions of fault self diagnosis, self recovery and protection, and carry out fault diagnosis and alarm for hardware, software and various external equipment in the system. In case of processing over travel, tool damage, interference, power failure and other accidents, the corresponding protection will be carried out automatically

5. Developing towards networking

the networking of CNC machine tools will greatly meet the needs of flexible production lines, flexible manufacturing systems and manufacturing enterprises for information integration. It is also the basic unit to realize new manufacturing modes, such as agilemanufacturing (AM), virtual enterprise (VE) and globalmanufacturing (GM). At present, the advanced numerical control system provides users with strong connection ability. In addition to RS232C interface, it also has DNC interface with remote buffer function, which can realize data communication between multiple numerical control machine tools and control multiple numerical control machine tools directly. Some have been equipped with the function of communicating with industrial local area and network interface, which promotes system integration and information integration, and makes remote programming, remote simulation, remote operation, remote monitoring and remote fault diagnosis possible

6. Developing towards standardization

numerical control standard is a trend of manufacturing information development. After the birth of numerical control technology for more than 50 years, the information exchange is based on ISO6983 standard, that is, using G and M codes to describe the machining process. Obviously, this process oriented description method has become increasingly unable to meet the needs of the rapid development of modern numerical control technology. To this end, a new CNC system standard iso14649 (STEP-NC) is being studied and formulated internationally. Its purpose is to provide a neutral mechanism that does not depend on specific systems and can describe a unified data model throughout the product life cycle, so as to realize the standardization of product information in the whole manufacturing process and even in various industrial fields

7. Parallel machine tools (also known as virtual axis machine tools) are the most revolutionary breakthrough of machine tool motion structure in the 20th century, such as enterprise standards, industry standards and so on. The parallel machine tool (see the figure) is composed of a base, a platform, and a number of retractable rods. The two ends of each rod are connected with the base respectively through spherical supports. The instructions for the use of the microcomputer screen display hydraulic universal experimental machine wew (6) 00D, and the telescopic movement is realized by the servo motor and ball screw according to the NC instructions, so that the moving platform drives the spindle parts or worktable parts to move in any track. The structure of parallel machine tool is simple but the mathematics is complex. The movement of the whole platform involves a considerable amount of mathematical operations, so parallel machine tool is a knowledge intensive mechanism. Compared with traditional series machine tools, parallel machine tools have the advantages of high stiffness, high bearing capacity, high speed, high precision, light weight, simple mechanical structure, low manufacturing cost, high degree of standardization, and have been successfully applied in many fields