Research and Application of Special Machining Technology

This paper discusses the emergence and development of special machining technology, expounds rapid prototyping, ultrasonic machining, electron beam and ion beam machining and laser machining, and discusses the technological principles and specific applications of various machining methods in production practice. Finally, the development direction of special machining technology is prospected.

Keywords: special handling; Rapid prototyping technology; Ultrasonic machining; Electron beam and ion beam machining; Laser processing

1. The emergence and development of special processing technology

As a processing method with a long history, machining has greatly promoted human material civilization and production activities. For industrial departments, the designed parts or machines must be realized by processing methods. Without effective processing methods, even the best design ideas cannot be transformed into products. For example, the steam engine was invented in the 1970s of 18, but the production equipment at that time could not produce the steam engine cylinder with high precision and high matching requirements, so it has been impossible to produce the steam engine that can work normally [1]. It was not until the appearance of cylinder boring machine that this production problem was solved, which made the steam engine widely used and caused the first industrial revolution. Therefore, we can find that processing methods play an important role in the realization of design ideas and the development of social economy.

With the development of production and the need of scientific experiments, the requirements for products are getting higher and higher. Future technical products are developing towards high precision, high speed, heavy load, high temperature and high pressure, miniaturization and high reliability. In order to meet these new requirements, new materials and new structures are needed. Therefore, many new requirements are put forward for the machinery manufacturing department. It is in this strong social demand that special processing is produced and developed, and its advantages over traditional processing further urge people to study and apply it. So far, there are many kinds of special processing technologies, and the processing accuracy and production efficiency that can be achieved are getting higher and higher. It can be said that special processing technology has become an indispensable processing method in modern machinery manufacturing.

Traditional mechanical processing uses mechanical energy and cutting force to process metals, while special processing mainly uses energy such as electric energy, chemical energy, light energy, acoustic energy and thermal energy to remove metals, so special processing technology can be used to process various metals or nonmetallic materials with high hardness, high strength, high brittleness and high toughness. Because special machining uses generalized tools, such as laser, ultrasonic, electron beam and ion beam, it is easy to realize full automation of machining process, which is of great significance to the organization and management of modern production.

Starting from 1943, paul raza Lianke and his wife in the former Soviet Union began to study the spark discharge corrosion phenomenon of switch contacts, and the special processing technology has experienced more than 60 years of development. At present, many special machining methods have been developed, such as EDM, WEDM, electrochemical machining and laser machining. Now, people have also studied the compound machining methods that apply special machining theory to traditional machining methods, such as vibration cutting and vibration milling. Because special machining technology is especially suitable for machining difficult-to-machine materials, complex surfaces and precise micro-surfaces, special machining has great applicability and development potential, and has been more and more widely used in the manufacture of tools, molds, measuring tools, instruments, spacecraft and microelectronic components. In the future, special machining will develop in the direction of improving machining accuracy and surface quality, improving production efficiency and automation, and developing compound machining and ultra-precision machining.

2. Rapid prototyping technology

Rapid Prototyping (RP) is an additive processing method, which is mainly used to make samples, so as to quickly evaluate, modify and test the design of new products and greatly shorten the development cycle of products. Rapid prototyping technology integrates mechanical engineering, CAD, numerical control technology, laser technology and material science and technology, which is easy to realize the automation of production process, efficient and convenient, so this sample manufacturing technology is increasingly applied to production practice. According to the materials and process principles used in rapid prototyping technology, it can be divided into four types: photosensitive resin liquid curing molding (SL), selective laser powder sintering molding (SLS), laminated sheet molding (LOM) and melt stacking molding (FDM).

3. Ultrasonic processing technology

The sound wave whose frequency exceeds 16000Hz is called ultrasonic wave. It is a longitudinal wave, which can transmit strong energy and produce hydraulic impact when it propagates in liquid medium. Ultrasonic machining technology (USM) is to use the tool end face to vibrate at ultrasonic frequency, and the abrasive suspension will produce mechanical impact, polishing and ultrasonic cavitation under the action of ultrasonic vibration to process brittle and hard materials. Because of the technological principle and characteristics of ultrasonic machining technology, ultrasonic machining has many special applications. Such as machining deep and small holes, grinding and polishing wire drawing dies and cavity dies, machining difficult-to-machine materials, ultrasonic vibration cutting, ultrasonic electrolytic composite machining, ultrasonic EDM composite machining, ultrasonic cleaning, ultrasonic cutting, etc. Ultrasonic machining technology and the development of new materials complement each other. In the future, ultrasonic machining will have more applications and development.

4. Electron beam and ion beam processing

Electron beam machining (EBM) is to use an electron beam with extremely high energy density to impact the surface of a workpiece at a very high speed, so that most kinetic energy is converted into heat energy, and the impacted workpiece material is partially melted and gasified, thus achieving the purpose of changing the physical and chemical properties, shape, size and position of the surface of the workpiece material. The electron beam processing device comprises an electron gun, a vacuum system, a control system and a power supply, and the electron beam is obtained by heating an emission cathode made of tungsten or tantalum. Due to the technological principle and characteristics of electron beam machining, electron beam machining technology can be used for machining holes and special surfaces, etching, welding, heat treatment and electron beam lithography.

Ion beam machining (IBM) uses the impact effect, sputtering effect and implantation effect when high-energy ion beams hit the surface of materials to carry out different machining. Because ion beam bombards materials to remove atoms layer by layer, it can achieve nano-scale machining accuracy. Ion beam machining can be divided into three types according to its machining principle and purpose: etching machining for removing materials from the workpiece, electroplating machining for coating on the surface of the workpiece and ion implantation machining for surface modification. Because electron beam and ion beam are easy to control accurately, the machining process can be fully automated, but there are still many technical problems to be solved in focusing and deflection of electron beam and ion beam.

5. Laser processing

Laser technology began in the 1960s and can be used for drilling, cutting, welding, heat treatment and laser storage. The generation of laser comes from the stimulated radiation of matter, that is, some matter with metastable energy level structure, which is excited by certain external photon energy, produces the so-called particle beam inversion phenomenon. In the state of particle beam inversion, if a photon with energy equal to the difference between the ground state and metastable state irradiates a substance, it will produce stimulated radiation and output a lot of light energy. Because laser has the characteristics of high intensity, good monochromaticity, good coherence and good directivity, it can be used to process almost any material. At present, the commonly used lasers are solid-state lasers (ruby lasers, rubidium glass lasers and rubidium-doped yttrium aluminum garnet lasers) and gas lasers (carbon dioxide lasers and argon ion lasers). In production practice, it is necessary to further study the factors affecting laser processing in order to make full use of laser processing technology.

6. Concluding remarks

In recent years, with the increasing demand for new materials, new structures, complex contour parts and parts with special requirements, special machining technology has been more and more widely used. In the future, with the further improvement of electromechanical control technology, special machining technology will be more automatic, and making full use of computer technology can make special machining develop towards automation and flexibility [2]. In the future, special machining technology will be more and more used in precision micro-machining, composite machining and green machining.

refer to

[1], white, Special Machining [M], Beijing: Machinery Industry Press, 20 1 1: 1 ~ 6.

Wang Jie, Fan Jun, et al. New progress of special processing technology [J]. Light Industry Machinery, 2008,26 (4): 5 ~ 7.

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