How about the development and trend of ultra-precision machining technology?

Since China listed “equipment manufacturing” as a national development strategy, China’s equipment manufacturing industry has made rapid progress. The manufacturing capabilities of many large-scale equipment have leapt to the world’s advanced level, or even the world’s top level, but made in China The industry as a whole is still backward, and its backwardness lies in the backwardness of precision manufacturing.

Ultra-precision processing technology is an important supporting technology for modern high-tech warfare, the basis for the development of modern high-tech industries and science and technology, and the development direction of modern manufacturing science.

The development of modern science and technology is based on experiments, and almost none of the required testing instruments and equipment does not require the support of ultra-precision processing technology. Moving from macroscopic manufacturing to microscopic manufacturing is one of the future development trends of manufacturing. At present, ultra-precision machining has entered the nano-scale, and nano-manufacturing is the frontier topic of ultra-precision machining. Developed countries in the world attach great importance to it.

The development stage of ultra-precision machining

The current ultra-precision machining, on the premise of not changing the physical properties of the workpiece material, to obtain the ultimate shape accuracy, dimensional accuracy, surface roughness, surface integrity (no or very little surface damage, including micro-cracks and other defects, residual stress , Organizational changes) as the goal.

The research content of ultra-precision machining, that is, various factors that affect the accuracy of ultra-precision machining include: ultra-precision machining mechanism, processed materials, ultra-precision machining equipment, ultra-precision machining tools, ultra-precision machining fixtures, ultra-precision machining detection and error Compensation, ultra-precision processing environment (including constant temperature, vibration isolation, clean control, etc.) and ultra-precision processing technology. For a long time, domestic and foreign scholars have carried out systematic research around these contents. The development of ultra-precision machining has gone through the following three stages.

1) From the 1950s to the 1980s, the United States took the lead in the development of ultra-precision machining technology represented by single-point diamond cutting, which was used in the processing of laser fusion mirrors, spherical and aspherical large parts in the fields of aerospace, defense, astronomy, etc. .

2) From the 1980s to the 1990s, it entered the initial stage of application in private industry. With the support of the government, companies such as Moore and Pritech, Toshiba and Hitachi in Japan, and Cranfield in Europe commercialized ultra-precision processing equipment and began to use them in the manufacture of precision optical lenses for civilian use. Single ultra-precision processing equipment is still scarce and expensive, mainly customized in the form of special machines. During this period, ultra-precision diamond grinding technology and grinders that can process hard metals and hard and brittle materials also appeared, but their processing efficiency could not be compared with diamond lathes.

3) After the 1990s, civil ultra-precision processing technology gradually matured. Driven by industries such as automobiles, energy, medical equipment, information, optoelectronics, and communications, ultra-precision processing technology is widely used in the processing of aspheric optical lenses, ultra-precision molds, disk drive heads, disk substrates, semiconductor substrates and other parts. As the related technologies of ultra-precision processing equipment, such as precision spindle parts, rolling guides, hydrostatic guides, micro-feed drives, precision CNC systems, and laser precision inspection systems, have gradually matured, ultra-precision processing equipment has become a common production in the industry. equipment. In addition, the accuracy of the equipment is gradually approaching the nanometer level, the size range of the workable workpieces has also become larger, and the application has become more and more extensive. With the development of numerical control technology, ultra-precision five-axis milling and flying cutting technology have also emerged. It has been possible to process complex parts such as non-axisymmetric aspheric surfaces.

The development of ultra-precision machining abroad

The countries where ultra-precision machining technology is in a leading position in the world are the United States, the United Kingdom and Japan. The ultra-precision processing technology in these countries not only has a high overall level of complete sets, but also has a very high degree of commercialization.

In the 1950s, the United States did not develop the ultra-precision cutting technology of diamond tools, called "SPDT technology" (Single Point Dia-mond Turning) or "micro inch technology" (1 microinch = 0.025μm), and developed the corresponding air bearing The ultra-precision machine tool of the main shaft is used to process large parts of spherical and aspherical surfaces for laser fusion mirrors, tactical missiles, and manned spacecraft.

Ultra-precision cutting of diamond tools

In terms of large-scale ultra-precision machine tools, the LLL National Laboratory in the United States successfully developed two large-scale ultra-precision diamond lathes in 1986: one is a horizontal DTM-3 diamond lathe with a machining diameter of 2.1m, and the other is a machining diameter of 1.65m. The LODTM vertical large-scale optical diamond lathe. Among them, the LODTM vertical large-scale optical diamond lathe is recognized as the world's most precise ultra-precision machine tool. The United States later developed a large 6-axis CNC precision grinding machine for precision grinding of large optical mirrors.

The Cranfield Institute of Precision Engineering (CUPE) affiliated to the Cranfield Institute of Technology in the UK is a unique representative of the level of ultra-precision machining technology in the UK. For example, the Nanocentre (nano machining center) produced by CUPE can be used for ultra-precision turning, with a grinding head, and ultra-precision grinding. The shape accuracy of the processed workpiece can reach 0.1μm, and the surface roughness Ra

Cranfield Precision Machining Center successfully developed the OAGM-2500 multi-function three-coordinate CNC grinding machine (table area 2500mm×2500mm) in 1991, which can process (grind, turn) and measure precision free-form surfaces. The machine adopts the method of merging machining parts, and can also process a large-scale reflector with a diameter of 7.5m in an astronomical telescope.

OAGM-2500 large cnc ultra-precision grinder

Japan’s research on ultra-precision processing technology started relatively late compared to the United States and the United Kingdom, but it is the fastest growing country in the world for ultra-precision processing technology.

The development of ultra-precision machining in my country

For a long period of time in the past, due to embargo restrictions imposed by Western countries, my country's import of foreign ultra-precision machine tools was severely restricted. But when my country's own CNC ultra-precision machine tools were successfully developed in 1998, Western countries immediately imposed a ban on my country, and my country has now imported many ultra-precision machine tools.

my country's Beijing Machine Tool Research Institute, Aviation Precision Machinery Research Institute (Aviation 303), Harbin Institute of Technology, National University of Defense Technology and other units are now able to produce several ultra-precision CNC diamond machine tools.

Beijing Machine Tool Research Institute is one of the main domestic research institutions of ultra-precision machining technology. It has developed many different types of ultra-precision machine tools, components and related high-precision testing instruments, such as precision bearings with an accuracy of 0.025μm, JCS —027 ultra-precision lathe, JCS-031 ultra-precision milling machine, JCS-035 ultra-precision lathe, ultra-precision lathe CNC system, photocopier drum processing machine, infrared high-power laser mirror, ultra-precision vibration-displacement micrometer, etc., to achieve Has achieved the domestic leading and international advanced level.

The NAM-800 nano CNC lathe is the latest generation of nano-level processing machine tools from Beijing Machine Tool Research Institute. It is the perfect unity of today's numerical control technology, servo technology, and mechanical manufacturing technology. This machine tool provides a good processing method for my country's cutting-edge technological development.

NAM-800 Nano CNC Lathe

The Ministry of Aerospace Industry 303 conducted in-depth research and product production in ultra-precision spindles and granite coordinate measuring machines.

Harbin Institute of Technology has carried out fruitful research on diamond ultra-precision cutting, diamond tool crystal orientation and sharpening, and diamond micro-powder grinding wheel electrolytic online dressing technology.

Tsinghua University has conducted in-depth research on integrated circuit ultra-precision processing equipment, disk processing and testing equipment, micro-displacement worktables, ultra-precision belt grinding and polishing, ultra-precision grinding of diamond micro-powder grinding wheels, and ultra-precision cutting of non-circular cross-sections. Research and have corresponding products come out.

In addition, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Huazhong University of Science and Technology, Shenyang No. 1 Machine Tool Plant, Chengdu Tool Research Institute, National University of Defense Technology, etc. have all carried out research in this field with remarkable results.

But in general, compared with foreign countries in terms of the efficiency, accuracy, and reliability of ultra-precision processing machine tools, especially the specifications (large size) and technical compatibility, there is still a considerable gap between our country and the actual production requirements. . In addition, the precision machining of complex curved surfaces has always been a barrier to the development of my country's manufacturing industry, and the development of the manufacturing industry is related to the long-term development of the country's economy, and a lot of research is still needed.

The development trend of precision machining

1. High precision and high efficiency.

High precision and high efficiency are the eternal theme of ultra-precision machining. In general, fixed abrasive grain processing continuously pursues the processing accuracy of free abrasive grains, while free abrasive grain processing continuously pursues the efficiency of fixed abrasive grain processing. Although the current ultra-precision machining technologies such as CMP and EEM can achieve extremely high surface quality and surface integrity, they are guaranteed by sacrificing processing efficiency. Although ultra-precision cutting and grinding technology has high processing efficiency, it cannot obtain the processing accuracy such as CMP and EEM. Exploring processing methods that can balance efficiency and precision has become the goal of researchers in the field of ultra-precision processing. The emergence of semi-fixed abrasive grain processing methods reflects this trend. On the other hand, it shows the birth of composite processing methods such as electrolytic magnetic grinding and magnetorheological abrasive flow machining.

2. Process integration.

Nowadays, the competition among enterprises is becoming fierce, and high production efficiency has increasingly become a condition for enterprises to survive. In this context, there have been calls for "replacement of research with grinding" and even "replacement of throwing with grinding". On the other hand, the trend of using one equipment to complete a variety of processing (such as turning, drilling, milling, grinding, and finishing) is becoming more and more obvious.

3. Large-scale and miniaturized.

In order to process large-scale optoelectronic devices (such as mirrors on large-scale astronomical telescopes) required by aviation, aerospace, aerospace and other fields, it is necessary to build large-scale ultra-precision processing equipment. In order to process micro-devices (such as micro-sensors, micro-drive components, etc.) required in the fields of micro-electronic machinery, optoelectronic information, etc., micro-ultra-precision processing equipment is required (but this does not mean that processing micro-small workpieces must require micro-mini processing equipment).

Ultra-precision machining technology is ushering in a prosperous era. The technology of ultra-precision cutting, ultra-precision grinding, ultra-precision grinding and polishing has made great progress. After processing, the surface accuracy of the workpiece can reach the nanometer or sub-nanometer level, and the processing methods are becoming diversified. In the production and manufacture of flowmeter sensors, in order to achieve high-precision measurement of products, precision processing technology ensures the processing accuracy of products.