At present, the technology of high power laser cutting and related equipment has been very mature in our country, but the independent research and application of the precision laser cutting technology is still in its infancy, which depends on the foreign import on both the laser cutting equipment and the processing technology. Therefore, in the face of the technological monopoly of western developed countries, mastering the manufacturing of precision laser cutting technology and related equipment will be of great significance for the development of national industry and the improvement of the competitiveness of China's science and technology.
As an advanced manufacturing technology in twenty-first Century, laser cutting has broad prospects for development. But it is not mature as a developing new technology. It has not formed a perfect theoretical and normative process as traditional processing technology. Therefore, in the process of laser cutting, we must investigate and learn from previous experience. Combined with the actual conditions, the most suitable processing technology is adopted. The progress of technology not only depends on the high performance equipment system and processing conditions, but also requires sufficient theoretical research and logical deduction, combined with a large number of process experiments and results analysis.
In the process of laser cutting of general materials, because of the fast cutting speed, the thermal deformation of the parts is very small. The size accuracy of the cutting parts depends mainly on the mechanical precision and control precision of the laser cutting machine worktable. In the process of pulse laser cutting, high precision cutting device and control technology are adopted, and the dimension accuracy can reach um level.
There is no uniform standard in quality evaluation of laser cutting. Up to now, there is no standard about laser cutting quality in China. The main basis for testing laser cutting quality is JIS and WES (welding specification). In CEN (European Standardization agency) and ISO (International Standardization Organization), there is standardization of laser cutting. The ISO9000 series quality assurance method is mainly provided by EU, and the laser cutting processing standard and standard sample specification are studied. The contents include: cutting quality grade division, setting sample and processing sample standard, optical system, price sample machine and light beam characteristics, etc.
For laser cutting processing, the evaluation of its machining quality mainly includes the following principles:
1. Smooth cutting, no stripe and no brittle fracture.
2. The width of slit is narrow, which is mainly related to the spot diameter of laser beam.
3. The perpendicularity of the cutting seam is good, and the heat affected zone is small.
4, no material burning, no melting layer formation, no big slag.
5. The rough surface of the cut is plated. The roughness of the surface is the key to measure the surface quality of laser cutting.
In addition to the above principles, the state of the melted layer and the final forming process directly affect the quality evaluation index.
The surface roughness of laser cutting is mainly determined by the following three aspects: (1) the intrinsic parameters of the cutting system, such as the pattern of spot, the focal length, etc.; (2) the adjustable technological parameters in the process of cutting, such as the power size, cutting speed, auxiliary gas type and pressure, etc.; (3) the physical parameters of the processed material, such as the absorption of the laser Rate, melting point, viscosity coefficient of molten metal oxide and surface tension of metal oxide. In addition, the thickness of the workpiece also has a great impact on the surface quality of laser cutting. Relatively speaking, the smaller the thickness of the metal workpiece, the higher the roughness of the cutting surface.
To obtain a better surface quality grade, we must optimize the processing parameters of laser power and cutting speed for many times. Generally speaking, for the materials with the same characteristics and thickness, the technological parameters have a set of optimal cutting parameters. The surface quality of different cuts will also be obtained. The metal material has low melting point, large thermal conductivity, small viscosity coefficient of molten material and small surface tension of metal oxide. It is easy to obtain high surface quality during laser cutting. Laser cutting is easy to measure the surface quality, but it is difficult to direct the measurement of the surface quality when it is fine machining or cutting some complex patterns. The surface quality can only be controlled with the help of the optimized test parameters. Therefore, in order to facilitate automatic cutting, the corresponding relationship between external optimization parameters and surface quality grades should be established.
标签:   钣金加工 激光切割加工