Views:9 Author:Site Editor Publish Time: 2020-12-16 Origin:Site
Because the cutting speed is fast in the laser cutting process of general materials, the thermal deformation of the parts is very small, the dimensional precision of cutting parts mainly depends on the mechanical precision and control precision of the laser cutting machine table.In pulse laser cutting, high-precision cutting device and control technology are adopted, and the dimensional accuracy can reach μm level.
There is not a unified standard for quality evaluation of laser cutting in the world.The main basis for testing laser cutting quality is JIS and WES (welding specification).There are issues related to the standardization of laser cutting in CEN (European Standardization Body) and ISO (International standardization body).
According to the ISO9000 series quality assurance methods provided by EU, the laser cutting standard and standard sample specification are studied, including: cutting quality grade classification, standard of sample setting and sample processing, optical system, machine type and beam characteristics of price sample, etc.
For laser cutting processing, the evaluation of its processing quality mainly includes the following principles:
1. Smooth cutting, no striations, no brittle fracture;
2. Narrow slit width, which is mainly related to the laser beam spot diameter;
3. Good perpendicularity of the slit and small heat affected area;
4. No material burning, no melting layer formation, no large slag;
5. Surface roughness, the size of the surface roughness is the key to measure the quality of laser cut surface.
In addition to the above principles, the state and final forming of the melting layer in the process of processing directly affect the above evaluation indexes of processing quality.
Laser cutting surface roughness mainly depends on the following three aspects:
1. The inherent parameters of the cutting system, such as spot mode and focal length;
2. Process parameters that can be adjusted during the cutting process, such as power size, cutting speed, auxiliary gas type and pressure, etc.;
3. Physical parameters of the processing material, such as laser absorption rate, melting point, melting metal oxide viscosity coefficient, metal oxide surface tension, etc.
In addition, the thickness of the workpiece also has a great influence on the surface quality of laser cutting.Relatively speaking, the smaller the thickness of the metal workpiece, the higher the roughness class of the cutting surface.
In order to obtain a good surface quality grade, the laser power, cutting speed and other technological parameters must be optimized several times.
In general, for materials with the same characteristics and thickness, there is an optimal set of cutting process parameters, which will also yield different cut surface qualities.The metal material has low melting point, high thermal conductivity, low viscosity coefficient of melt and low surface tension of metal oxide, so it is easy to obtain higher surface quality when laser cutting.
When laser cutting plate, it is easy to measure the surface quality, but when fine machining or cutting some complex patterns, it is difficult to measure the surface quality directly, so the surface quality can only be controlled by optimizing the test parameters.
Therefore, in order to facilitate automatic cutting, the corresponding relationship between external optimization parameters and surface quality level should be established.