1Laser precision processing

Because of its excellent beam characteristics, laser has played a very important role in the field of industrial processing since its birth, and has continuously penetrated into various fields of industrial production. With its unique advantages, it has become an important processing method for the future manufacturing industry. , Known as the processing technology of the 21st century.

Laser precision processing uses a high-intensity laser beam. After being focused by an optical system, the power density of the laser beam reaches 104~1011W/cm2. The processing workpiece is placed near the focus of the laser beam, and the relative movement of the laser beam and the processing workpiece is achieved. For thermal processing of processed workpieces, the processing accuracy is generally from a few microns to tens of microns.

The laser beam can be focused to a small size, so it is especially suitable for precision processing. The lasers used in laser precision processing are various pulsed or Q-switched solid-state lasers, semiconductor lasers, pulsed Nd? YAG lasers, and fiber lasers and ultraviolet lasers that have been continuously promoted in recent years. Various pulse lasers have very small focus spots, large power density, small heating range of the workpiece, high processing accuracy and positioning accuracy, and small heat-affected zone. Compared with general mechanical processing, laser precision processing has many advantages:

(1) The range of processing objects is wide. Almost all metal materials and non-metal materials such as steel, heat-resistant alloys, ceramics, gems, glass, cemented carbide and composite materials can be processed.

(2) The machining accuracy is high, and it is generally better than other traditional machining methods, such as EDM, electron beam machining, etc.

(3) It belongs to non-contact processing, no tool wear, heat-affected zone and small deformation, so very tiny parts can be processed. Moreover, the energy of the laser beam can be controlled and the moving speed can be adjusted.

(4) The degree of automation is high, it can be controlled by a computer, the processing speed is fast, the work efficiency is high, and the processing of any complex shape can be easily performed.

(5) Most lasers can be used in combination with optical fiber systems. The combination of innovative fiber delivery systems and lasers greatly increases the convenience and flexibility of the laser processing system. This combined system is suitable for simultaneous processing of multiple workbenches in the industry. And robot or manipulator operation is very ideal.

In summary, laser precision processing technology has many advantages that traditional processing methods cannot match, and its application prospects are very broad.

At present, the lasers used for laser precision processing mainly include medium and low power Nd? YAG lasers, excimer lasers, fiber lasers, solid-state ultraviolet lasers, etc. In recent years, fiber lasers and ultraviolet lasers have developed very rapidly. In China, the output power of the ytterbium-doped double-clad fiber laser developed by the Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences has continuously achieved breakthroughs; UV lasers of various bands have also broken through the milliwatt level and are moving towards practicality. In foreign countries, hundreds of watts and kilowatts of fiber lasers have been industrialized and have been widely used in the industrial field, and low-power ultraviolet lasers of various bands have also been used. According to literature reports, at present, practical and compact 266nm deep ultraviolet light sources have been successfully developed abroad. For example, AppliedMaterialCO in the United States uses LD array pumping Nd? YAG crystal to generate 1064nm fundamental frequency light, and then obtains the output through the quadruple frequency method. A continuous laser with a power of 3W and a wavelength of 266nm can realize laser precision processing and marking of transparent workpieces or glossy metals.

Compared with other lasers used for precision processing, fiber lasers and ultraviolet lasers have better beam characteristics (Table 1 shows the main performance comparison of several lasers). In my country, these two lasers have gradually become more widely used in recent years. Applications. Among them, Shenzhen Han's Laser Technology Co., Ltd. launched the M355 UV laser marking machine. After focusing, the laser spot diameter reached 5μm. The Laser Processing Technology Laboratory of South China Normal University has independently designed and developed a 50W fiber laser precision cutting system. The system uses a 50W ytterbium-doped double-clad fiber laser produced by IPG in the United States. After focusing, the laser spot diameter reaches 15μm. Both types of laser precision processing equipment have been favored by the market.