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Laser precision machining technology
自1960年美国贝尔实验室发明红宝石激光器以来后，激光就逐步地被应用到音像设备、测距、医疗仪器、加工等各个领域。 Laser processing is currently the most advanced processing technology. Since the ruby laser was invented by Bell Labs in the United States in 1960, laser has been gradually applied to various fields such as audio-visual equipment, distance measurement, medical instruments, processing and so on. In the field of laser processing, although laser emitters are very expensive (hundreds of thousands to millions), because laser processing has advantages unmatched by traditional processing, laser processing has accounted for 50% of the processing industry in the United States, Italy and Germany % Share.
Because the laser beam can be focused to a very small size, it is particularly suitable for precision machining. According to the size and accuracy of the processed materials, the current laser processing technology is divided into three levels:
(1) Laser processing technology for large-scale materials, with thick plates (several millimeters to tens of millimeters) as the main object, and its processing accuracy is generally at the millimeter or sub-millimeter level;
(2) Precision laser processing technology, with thin plates (0.1 to 1.0 mm) as the main processing object, and its processing accuracy is generally in the order of ten microns;
(3) Laser micro-machining technology, for various films with a thickness of less than 100 μm as the main processing object, its processing accuracy is generally below ten microns or even sub-micron level.
In the machinery industry, precision usually means small surface roughness and a small range of tolerances (including position, shape, size, etc.). The "precision" mentioned here means that the gap in the area to be processed is small, that is, the limit size that can be processed is small.
Laser precision machining has the following significant features:
(1) Wide range: The scope of laser precision machining is wide, including almost all metallic and non-metallic materials; suitable for sintering, drilling, marking, cutting, welding, surface modification and chemical vapor deposition of materials, etc. . While electrolytic processing can only process conductive materials, photochemical processing is only suitable for easily corrosive materials, and plasma processing is difficult to process some materials with high melting points.
(2) Precise and detailed: The laser beam can be focused to a small size, so it is especially suitable for precision machining. Laser precision machining has few influencing factors and high machining accuracy, and is generally superior to other traditional machining methods in general.
(3) High-speed and fast: From the perspective of the processing cycle, the tool electrodes of EDM require high accuracy, large losses, and long processing cycles; the design of the cathode mold for the processing cavity and profile of electrolytic processing is heavy, and the manufacturing cycle Very long; the photochemical processing process is complicated; and the laser precision processing is simple and the slit width is easy to adjust. It can immediately perform high-speed engraving and cutting based on the computer output pattern. The processing speed is fast and the processing cycle is shorter than other methods.
(4) Safe and reliable: Laser precision machining belongs to non-contact machining, which does not cause mechanical extrusion or mechanical stress on the material; compared to EDM and plasma arc machining, its heat affected zone and deformation are small, so it can be processed very little Parts.
(5) Low cost: not limited by the number of processing, laser processing is cheaper for small batch processing services. For the processing of large products, the mold manufacturing cost of large products is very high. Laser processing does not require any mold manufacturing, and laser processing completely avoids the sags formed during punching and shearing of materials, which can greatly reduce the production costs of enterprises and improve products. Grade.
(6) The cutting seam is small: The cutting seam for laser cutting is generally 0.1-0.2mm.
(7) The cutting surface is smooth: there is no burr on the cutting surface of laser cutting.
(8) Small thermal deformation: The laser cutting has a narrow slit, fast speed, and energy concentration, so the heat transferred to the material to be cut is small, and the deformation of the material is also very small.
(9) Material saving: The laser processing uses computer programming, which can tailor products of different shapes to maximize the utilization of materials and greatly reduce the material cost of the enterprise.
(10) It is very suitable for the development of new products: once the product drawing is formed, laser processing can be performed immediately, and you can get the actual product of the new product in the shortest time.
(1) Laser precision drilling
With the advancement of technology, the traditional punching method has been unable to meet the needs in many occasions. For example, small holes with diameters of several tens of micrometers are processed on hard tungsten carbide alloys; deep holes with diameters of several hundred micrometers are processed on hard and brittle red and sapphire, etc., which cannot be achieved by conventional machining methods. The instantaneous power density of the laser beam is as high as 108 W / cm2, which can heat the material to the melting point or boiling point in a short period of time to achieve perforation on the above materials. Compared with electron beam, electrolysis, electric spark, and mechanical drilling, laser drilling has good quality, high repeat accuracy, strong versatility, high efficiency, low cost, and significant comprehensive technical and economic benefits. Laser precision drilling has reached a very high level abroad. A Swiss company uses solid-state lasers to punch holes in aircraft turbine blades, which can process microholes with a diameter from 20 μm to 80 μm, and the ratio of diameter to depth can reach 1:80. The laser beam can also process various special-shaped holes such as blind holes and square holes on brittle materials such as ceramics, which cannot be achieved by ordinary machining.
(2) Laser precision cutting
Compared with traditional cutting methods, laser precision cutting has many advantages. For example, it can make narrow incisions, almost no cutting residue, small heat-affected zone, low cutting noise, and can save 15% to 30% of material. Since the laser hardly produces mechanical impulse and pressure on the material being cut, it is suitable for cutting hard and brittle materials such as glass, ceramics and semiconductors. In addition, the laser spot is small and the slit is narrow, so it is particularly suitable for small parts. Kind of precision cutting.
A typical application of laser precision cutting is cutting SMT stencils on printed circuit boards (SMT stencils) in printed circuits boards. The traditional SMT template processing method is a chemical etching method. Its fatal disadvantage is that the limit size of the processing must not be less than the thickness of the plate, and the chemical etching method has a complicated process, a long processing cycle, and the corrosive medium pollutes the environment. Using laser processing can not only overcome these shortcomings, but also reprocess the finished template. In particular, the machining accuracy and gap density are significantly better than the former. . However, due to the high technical content of the entire equipment for laser processing, the price is also high.