Trend and thinking of the hottest ultra precision

2022-08-16
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Trend and thinking of ultra precision machining

after decades of efforts, ultra precision machining has become increasingly mature. Whether it is ultra precision machine tools, diamond tools, or ultra precision machining technology, a complete set of ultra precision manufacturing technology system has been formed, which has laid the foundation for promoting the development of mechanical manufacturing to a higher level. Now it is moving towards nano precision or nano precision, and its prospect is very encouraging. But from another perspective, with the development of science and technology, its requirements are higher and higher, and the actual situation is restricted by the level of technology, there are still many difficulties

1 overview

ultra precision machining technology is a comprehensive system engineering. Its development comprehensively utilizes the progress of machine tools, tools, metrology, environmental technology, microelectronics technology, computer technology, numerical control technology and so on. Professor tsukawa Hideo of Japan vividly compares ultra precision machining to the top of Mount Fuji, so in a sense, it has reached the peak of precision machining. In Japanese literature, it is often mentioned that the internal and external lubrication achieves the best effect and is close to the limit. Although it is somewhat vague from a technical point of view, it is very visual. In fact, it is quite difficult to improve the machining accuracy at the current level. In terms of current products, most of the dimensions with high requirements exceed the existing standards, which reflects the actual situation of ultra precision from another side. A considerable number of requirements are expressed in the form of technical conditions or marked with specific special tolerances. Today, in addition to accuracy, there are new requirements for the surface - surface integrity. Professor Taniguchi often introduces ultra precision machining technology and micro machining together, which objectively reflects the intersection of the two technologies and the characteristics of the times. This paper wants to explain some personal views on the development trend of ultra precision machining

with the extension of time, the precision, difficulty and complexity of ultra precision machining technology are developing to a higher level, so that the machining technology also needs to be constantly updated to adapt to it

taking diamond cutting as an example, the arc radius of its cutting edge has been developing in a smaller direction, because its size directly affects the roughness of the machined surface and is directly related to the reflectivity of the optical mirror. Now the reflectivity requirements are getting higher and higher. For example, the reflectivity of the laser gyro mirror has been proposed to be 99.99%, which inevitably requires the diamond tool to be sharper. According to Dr. Shangyi Shimada of Osaka University in Japan, In order to carry out the thinning test, the goal is to achieve the thickness of the chip of 1nm, and the arc radius of its cutting edge approaches 2 ~ 4nm. Up to now, this level is still the highest in the world. In order to reach this height, the diamond grinder has also changed the traditional structure, and uses air bearings as the support. The end face runout of the grinding disc can be self corrected on the weak binding force of the machine tool, so that its end face runout can be controlled below 0.5 m. the edge grinder developed by the aviation system 303 of our country is an example. The cutting edge was sharp, and then its detection became a problem. At first, Professor Ichio Nakayama of Yokohama University in Japan used the method of gold wire indentation; Later, scanning electron microscope (SEM) was developed, and its measurement accuracy can reach 50nm; With the further improvement of accuracy, Japan's tool tip evaluation committee added a secondary electron emission device to SEM, and at this time, it can only measure 20 ~ 40nm; In 1993, the group proposed to use scanning tunneling microscope (STM) or atomic force microscope (AFM) for detection, but it has not been reported since. Until 1996, Huazhong University of technology in China published a report on AFM detection. In 1998, Harbin Institute of Technology reported again. The arc radius of the cutting edge is successfully measured by AFM. The breakthrough of detection technology has created a prerequisite for further exploration of micro cutting mechanism

hard and brittle materials are generally processed by grinding and other methods. Later, Professor Masahiro Miyazawa of zuri University in Japan published that diamond grinding wheel can be used to control the cutting depth and tool travel. On ultra precision grinding machine, ductile grinding can be carried out, and even the surface of glass can be used to obtain optical mirror. This is a great breakthrough in technology. Then, the diamond turning tool with large negative rake angle is developed. Under the above similar conditions, the same results can be obtained, but the turning efficiency is significantly improved. Today, it is proposed that if ultrasonic technology is combined with diamond cutting, it will be more beneficial to play its role. Jilin University of technology in China has also made such an attempt and achieved results

the grinding wheel adopts metal bond, which generally refers to copper. In order to improve the service life of the grinding wheel, Professor Weixiong Nakagawa of Tokyo University of technology in Japan adopted cast iron bond, which significantly improved the service life of the grinding wheel. This is a great breakthrough, and then caused a research upsurge of various bonds. Later, on this basis, Ohmori of the Japanese Institute of physics and chemistry developed the electrolytic dressing (ELID) technology of grinding wheels, which widened the way of ultra precision machining technology and made progress in mirror machining

In recent decades, the development of diamond technology has given great encouragement to scientific and technological personnel. From natural diamond to artificial diamond, from superhard diamond film to the formation of thick film, it has gradually created a beautiful prospect for the wide use of diamond tools in ultra precision manufacturing technology. In order to broaden the application field of diamond and make a breakthrough in diamond cutting ferrous metals, a large number of practices have been carried out, such as cryogenic cutting, cutting in carbon rich atmosphere, etc., which have achieved some results successively. Boron is also added to the composition of diamond to significantly improve its affinity with ferrous metals. Nowadays, diamond grinding has been exploring other ways, such as thermochemical grinding

the mechanism of micro cutting has always been a major concern of technicians, but it is extremely difficult to observe the cutting points directly. Now it is proposed to miniaturize the cutting device and place it in the mirror of SEM to change the relevant provisions of the experimental machine: 1 Changing the model of the testing machine should comply with the rules of relevant specifications; 2. Changing the design of the experimental machine should be reasonable in structure, beautiful in appearance, simple in operation and convenient for maintenance; 3. Accessories and things of the application function of the experimental machine should be randomly supplied under the head for cutting and observation; Professor Naoya Igawa of Osaka University in Japan and others began to use computer simulation, and gradually approached the mystery of the requirements of micro cutting tensile testing machine for fixture materials

the development of ultra precision machine tools has been quite mature. It is the most important hardware, which integrates a large number of achievements, such as high-precision spindle, micro feed device, high-precision positioning system, air flotation guide rail technology, thermal stability technology, NC system, etc. In particular, LLNL laboratories in the United States, bueryue in Japan, Toshiba machinery and other companies in the United Kingdom

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