Compared with the traditional cutting method, the fiber laser cutting machine has obvious advantages in high cutting accuracy and narrow slit effect. With the development of manufacturing industry, the quality of laser cutting is required to be higher and higher. Especially in the aviation field, when 3D laser cutting complex curved sheet metal parts, it is necessary to adjust the laser head posture and process parameters in real time according to the curvature of the surface to ensure the cutting quality. Through the simulation system, employees can not only intuitively master the laser cutting process to ensure the reliability of the processing code, but also optimize some problems in the cutting process to ensure the cutting quality. In actual cutting, in order to meet the processing needs of different types of metal plates, various three-dimensional laser cutting platforms should be used for processing according to the size, processing accuracy and shape characteristics of the plates. At present, the virtual site construction efficiency of laser cutting simulation software is low, the platform switching is complex, the learning cost is high, the realization of cutting traces is insufficient, and the process processing module is imperfect. This paper analyzes how to set the parameters and quality control of fiber laser cutting machine.

The parameters of the fiber laser cutter include cutting height, cutting nozzle type, focusing position, cutting power, cutting frequency, cutting duty ratio, cutting air pressure and cutting speed. Hardware conditions include protective lens, gas purity, plate quality, focusing mirror and collimating mirror. The laser cutting analyzes the cutting quality and cutting efficiency respectively, and analyzes the influence of different types, and adjusts various required parameters through the combination of laser cutting.

Cutting speed

The laser head of the laser cutting machine can move along the shape of the part in unit time. The higher the laser cutting speed, the shorter the cutting time, and the higher the laser cutting production efficiency. However, when other parameters are fixed, the laser cutting speed is not linear with the cutting quality. A reasonable cutting speed is a range value. Below this range, the energy of the laser beam remains too much on the surface of the part, resulting in excessive combustion. If the range value is exceeded, the energy of the laser beam is too late to completely melt the part material, which makes it difficult to cut through.

Power of the laser machine

The laser output power is the output energy of the laser system. Laser cutting represents the ability of the laser beam to melt materials per unit time.

Focus position

The laser output is finally focused on the point with the highest power density through a special lens. The focal spot diameter is proportional to the focal depth of the focusing lens. The focus of the fiber laser cutter is set according to the different thickness at different positions. The correct focus position is an important condition for obtaining stable cutting quality. The cutting quality of laser cutting is not only related to the laser beam, but also related to the characteristics of the laser beam focusing system, that is, the size of laser cutting after focusing has a great impact on the quality of laser cutting.

Gas pressure

Make a cut in the gap. Proper air pressure can help speed up laser cutting, and the size of auxiliary air pressure will also affect the cutting efficiency of optical fiber laser cutting machine. If the thickness of the laser cutting material increases or the cutting speed is slow, the air pressure should be reduced appropriately. Cutting with lower air pressure can prevent frosting.

Nozzle distance

The focused laser is applied to the surface of the part through a copper nozzle. The distance between the workpiece and the laser nozzle is called the nozzle distance. The distance from the nozzle to the part is measured according to the flow and pressure. If the distance is too far, the blowing force of gas is too large, and the exhaust flow is too large, splashing will be affected. The appropriate distance is 0.8-1.0mm. Select different types of nozzles according to different material thicknesses.

For example, for a material with a thickness of 3 mm, the focus position is adjusted to - 4 mm, the nitrogen cutting pressure is 12 PA, the nozzle distance is 1 mm, the power of the fiber laser cutting machine is 3000 W, and the cutting speed is 12 m / min. because various parameters are well adjusted, the cutting conditions are good. After various tests, after adjusting the parameters to the most suitable conditions, the cutting surface will be smooth.

What are the specific debugging steps? When the fiber laser cutting quality is poor, it is recommended to conduct a general inspection first. The main contents and sequence of general inspection are:

1. Cutting height. It is recommended that the actual cutting height be 0.8~1.2mm. If the actual cutting height is inaccurate, calibration is required.

2. Check whether the type and size of the cutting edge are used incorrectly. If it is correct, check whether the notch is damaged and whether the roundness is normal.

3. It is recommended to use a cutting port with a diameter of 1.0 for optical center detection. The focal point of optical center detection should be between - 1 and 1. This makes the light spot small and easy to observe.

4. Check whether the protective lens is clean, free of water, oil and slag. Sometimes, the protective glasses are fogged due to the weather or the air is too cold during paving.

5. Focus check whether the focus setting is correct. If the cutting head focuses automatically, be sure to use the mobile phone APP to check whether the focusing is correct.

6. Modify cutting parameters.

After the above five items are checked, modify the parameters according to the cutting phenomenon of the optical fiber laser cutting machine. How to adjust parameters according to this phenomenon? Here is a brief introduction to the conditions and solutions that stainless steel and carbon steel will encounter when cutting.

For example, there are many types of stainless steel slag hanging. If there is only slag hanging at the corner, the roundness of the corner can be considered, and the parameters can reduce the focus and increase the air pressure. If the whole slag is hanging, it is necessary to reduce the focus, increase the air pressure, and increase the cutting port. However, if the focus is too low or the air pressure is too low, the section delamination and surface roughness will be caused. In case of overall granular soft slag, the cutting speed can be appropriately increased or the cutting power can be reduced.

Fiber laser cutting machine may also encounter when cutting stainless steel. When cutting the slag hanging on the proximal side, check whether the gas supply is insufficient and the gas flow cannot keep up with it. When cutting carbon steel with fiber laser cutting machine, the thin plate section is not bright enough and the thick plate section is rough.

Generally speaking, the brightness of 1000W laser cutting carbon steel is not more than 4mm, that of 2000W is 6mm, and that of 3000W is 8mm. If you want to cut the part to achieve a bright effect, first of all, the quality of the plate is good, and the surface is free of rust, oxidation paint and skin. Secondly, the purity of oxygen should be high, at least above 99.5%. In cutting, attention shall be paid to that the small cutting nozzle shall be used for double-layer 1.0 or 1.2, and the cutting speed shall be faster than 2m/min, and the cutting air pressure shall not be too high.

To ensure that the fiber laser cutting machine can achieve the ideal effect when cutting thick plates, first ensure that the plate quality is high and the gas purity is high. Second, pay attention to the selection of cutting ports. The larger the aperture is, the better the section quality will be, but at the same time, the greater the section taper will be. Therefore, to ensure good cutting effect, it is necessary to conduct appropriate parameter debugging.

About HGTECH: HGTECH is the pioneer and leader of laser industrial application in China, and the authoritative provider of global laser processing solutions. We have comprehensively arranged laser intelligent equipment, measurement and automation production lines, and smart factory construction to provide overall solutions for intelligent manufacturing.