Numerical control technology is a technology that uses digital information to control mechanical motion and working processes. It is a modern manufacturing industry that integrates traditional mechanical manufacturing technology, computer technology, modern control technology, sensor detection technology, network communication technology and opto-mechanical technology. The basic technology of the company has the characteristics of high precision, high efficiency, flexible automation, etc., which plays a pivotal role in the realization of flexible automation, integration and intelligence in the manufacturing industry.
- Digital control. Numerical Control is a technology that uses digital signals to automatically control the control object (such as the movement of a machine tool and its machining process), which is referred to as numerical control for short.
- Numerical control technology. Numerical control technology refers to the automatic control technology that uses numbers, letters and symbols to program a certain working process.
- Numerical control system. Numerical control system refers to the organic integrated system of software and hardware modules that realize the related functions of numerical control technology, and it is the carrier of numerical control technology.
- Computer numerical control system. Computer numerical control system refers to the numerical control system with computer as the core.
- CNC machine tools. NC Machine refers to a machine tool that uses numerical control technology to control the machining process, or a machine tool equipped with a numerical control system.
1. Overview of CNC technology in developed countries
Numerical control technology continues to develop with the advancement of modern technology, especially microelectronics and computer technology. Developed countries generally attach importance to the machine tool industry, continue to study the development direction of machine tools and propose scientific research tasks, and for this purpose, they have recruited worldwide talents and provided sufficient funds. The United States, Germany, and Japan are countries with relatively advanced technology and rich experience in the scientific research, design, manufacturing, and use of CNC machine tools in the world today.
The United States has developed a large number of automatic lines required for mass production automation due to its advanced automobile and other manufacturing industries and the world’s leading position in electronics and computer technology. The mainframe design, manufacturing and numerical control system of its CNC machine tools have a solid foundation, and it has always attached importance to scientific research and innovation. Its high-performance CNC machine tool technology has also been leading the world. Today the United States not only produces high-performance CNC machine tools for the machining of aerospace products, but also produces cheap and practical CNC machine tools for small and medium-sized enterprises.
Germany attaches importance to the important strategic position of the machine tool industry. German CNC machine tools, especially large, heavy, precision CNC machine tools. Due to their good quality and performance, advanced and practical, they enjoy a high reputation in the world. Germany attaches great importance to the advanced and high-quality CNC machine tools and accessories. Its mechanical, electrical, hydraulic, pneumatic, optical, cutting tools, measurement, CNC systems and various functional components are among the top in the world in terms of quality and performance. For example, Siemens’ CNC system and Heidenhain’s precision grating are world-famous.
Japan is also similar to the United States and Germany, fully developing automatic mass production lines, and then fully developing CNC machine tools for small and medium batch flexible production automation. In terms of mid-range CNC machine tools, Japan’s export volume ranks first in the world. Since the 1980s, Japan has further strengthened scientific research and developed high-performance CNC machine tools. Japan highlights the development of numerical control systems. The numerical control system produced by Japan’s FANUC company is technologically advanced and ranks first in the world in terms of output.
2. Overview of CNC technology in China
China’s factories producing CNC machine tools account for about 1/3 of the total number of machine tool factories. The output of CNC machine tools continues to grow, but the demand for CNC machine tools is growing faster. The output of domestic CNC machine tools cannot meet the needs of social development. A large number of CNC machine tools need to be imported.
From the development of China’s first CNC machine tool in 1958 to the current development of CNC machine tools, it can be roughly divided into two major stages:
The period from 1958 to 1979 was the first stage, and the period from 1979 to the present was the second stage. In the first stage, the stability and reliability of the CNC system have not been well resolved, which limits the development of domestic CNC machine tools. The CNC wire-cutting machine tool has been developed rapidly due to its simple structure. In the second stage, the reliability and stability of CNC machine tools were solved through the introduction of advanced CNC technology and cooperative production, and the CNC machine tools began to be mass-produced and used. After the second stage of development, the design and manufacturing technology of China’s CNC machine tools has been greatly improved. Vertical machining centers, horizontal machining centers, CNC lathes, CNC milling machines and other CNC machine tools have been developed; some CNC machine tools have been trained Talents in design, manufacturing, use and maintenance; through the use of foreign advanced components and numerical control system supporting, we can design system supporting, and can design and manufacture high-speed, high-performance, multi-faceted, multi-axis CNC machine tools. On the basis of the machining center, a flexible manufacturing unit was developed and a flexible manufacturing system was built. By the end of the 1980s, China had explored and implemented CIMS (Computer Integrated Manufacturing System) within a certain range, gained valuable experience and mastered certain technologies.
Although China’s CNC technology has developed to a certain extent, there is still a big gap compared with other advanced countries. The number and variety of CNC machine tools in China cannot fully meet the needs of the Chinese market, and the export volume is small; the design and manufacturing level is still in the stage of learning, copying and self-development; there is a serious shortage of experts and skilled workers in various fields; important functional components and automated tools The numerical control system needs the support of foreign technology; it also needs to improve the test, digestion, mastery and innovation capabilities of key technologies.
With the world’s scientific and technological progress and the development of the machine tool industry, CNC machine tools, as the mainstream product of the machine tool industry, have become the key equipment for realizing the modernization of the equipment manufacturing industry and the strategic material for the development of national defense and military equipment. China’s aerospace, defense and military industries require large-scale, high-speed, precision, multi-axis, and high-efficiency CNC machine tools; automobile, motorcycle, and home appliance manufacturing industries require high-efficiency, high-reliability, and high-automation CNC machine tools and complete sets of flexible production lines; power station equipment, Metallurgical and petrochemical equipment, rail transit equipment, shipbuilding, and manufacturing require high-precision, heavy-duty CNC machine tools; IT, bioengineering and other high-tech industries require nano- and sub-micron super-precision machining CNC machine tools; industrial upgrading engineering machinery Traditional manufacturing industries such as, agricultural machinery, especially the booming private enterprises, require a large number of CNC machine tools for equipment. Therefore, accelerating the development of the CNC machine tool industry is also a realistic requirement for the development of China’s equipment manufacturing industry.
Numerical control technology is composed of three parts: machine tool body, numerical control system and peripheral technology.
The main body of the machine tool is mainly composed of basic parts such as bed, column, guide rail, worktable, etc. and supporting parts such as tool rest and tool magazine.
The CNC system is composed of input/output equipment, Computer Numerical Control, Programmable Logic Control, PLC and spindle servo drive device, feed servo drive device and measuring device. Among them, the computer numerical control device is the core of the numerical control system.
Peripheral technology mainly includes tool technology (mainly refers to tool system), programming technology and management technology
The Features Of NC Technology
1. Improve machining accuracy
The CNC machine tool is a highly comprehensive mechatronics product. It is composed of precision machinery and automatic control system. It has high positioning accuracy and repeat positioning accuracy. The transmission system of the machine tool and the structure of the machine tool have high rigidity and heat. Stability: Measures are taken to reduce errors when designing the transmission structure, and the numerical control system automatically compensates. Therefore, the numerical control machine tool has a higher machining accuracy, especially the consistency of the same batch of parts machining, and the product quality is stable. The pass rate is high, which cannot be compared with ordinary machine tools.
2. Improve production efficiency
The CNC machine tool can use a larger cutting amount, which effectively saves machining time. The CNC machine tool or machining center also has automatic speed change, automatic tool change and other automatic operation functions, which greatly shortens the auxiliary time, and once a stable machining process is formed, there is no need for inspection and measurement between procedures. Therefore, the productivity of CNC machining is 3-4 times higher than that of ordinary machine tools, or even more.
3. Improve adaptability
The CNC machine tool performs automatic machining in accordance with the CNC program of the processed part. When the machining object changes, it is only necessary to change the CNC program without using special process equipment such as profiling and prototype. This is conducive to shortening the production preparation cycle and promoting the upgrading of products.
4. Improve the machinability of parts
Some mechanical parts formed by complex curves and curved surfaces are difficult to process or even impossible to be processed by conventional process methods and manual operations. However, it can be easily realized by CNC machine tools with multi-axis linkage.
5. Improve economic efficiency
Numerical control machine tools (especially machining centers) mostly use process concentration, one machine is multi-purpose, in the case of one clamping, can complete most of the process of parts machining, one CNC machine tool or machining center can replace several ordinary machine tools. This can not only reduce the installation error, save the auxiliary time of transportation, measurement, and installation between procedures, but also reduce the types of machine tools, save the area of the machine tool, and bring higher economic benefits.
The Application Of NC Technology
From the perspective of the world’s numerical control technology and its equipment applications, its main application areas are as follows:
1. Manufacturing industry
The machinery manufacturing industry is the first industry to apply numerical control technology, and it is responsible for providing advanced equipment for various industries in the national economy. The main applications include the development and production of high-performance five-axis high-speed vertical machining centers, five-axis high-speed vertical machining centers, large-scale five-axis gantry mills, etc. for modern military equipment; CNC machine tools used in the flexible processing production lines of engines, gearboxes, and crankshafts in the automotive industry And high-speed machining centers, as well as welding, assembly, painting robots, plate laser welding machines and laser cutting machines, etc.; high-speed five-axis machining centers for processing propellers, engines, generators, and turbine blades in the aviation, shipbuilding, and power generation industries, and heavy-duty Turning and milling compound machining center, etc.
2. Information Industry
In the information industry, from computers to networks, mobile communications, telemetry, remote control and other equipment, it is necessary to adopt manufacturing equipment based on ultra-precision technology and nanotechnology, such as wire bonding machines for chip manufacturing, wafer lithography machines, etc. These equipment All of the control requires the use of CNC technology.
3. Medical equipment industry
In the medical industry, many modern medical diagnosis and treatment equipment adopt numerical control technology, such as CT diagnostic equipment, whole body treatment machines, and minimally invasive surgical robots based on vision guidance. Orthodontics and tooth restoration in stomatology are required High-precision CNC machine tools are used to process and produce teeth.
4. Military equipment
Many modern military equipment uses a large number of servo motion control technologies, such as automatic aiming control of artillery, tracking control of radar, and automatic tracking control of missiles.
5. Other industries
In the light industry, there are printing machinery, textile machinery, packaging machinery and woodworking machinery that use multi-axis servo control; in the building materials industry, there are CNC waterjet cutting machines for stone processing, and CNC glass carving machines for glass processing. CNC sewing machines for Simmons processing and CNC embroidery machines for garment processing; in the art industry, more and more handicrafts and artworks will be produced using high-performance five-axis machining centers