Some of the most easily encountered problems in the use of laser cutting machines

1. Cutting and piercing technology
Any thermal cutting technology usually requires a small hole in the plate, except for a few cases where it starts at the edge of the plate. Previously, in the laser stamping compound machine, we used a punch to punch out a hole of our own, and then we used the laser to develop from the small hole for research and cutting. There are two basic methods to penetrate the laser cutting machine without a piercer:

Blasting perforation - the material can form its own pit in the center after being irradiated by a continuous laser, and then the molten material and the students can be removed by the oxygen flow coaxial with the laser beam to form such a hole. In general, the size of the hole is related to the thickness of the plate, and the average diameter of the blast hole is half of the thickness of the plate. Therefore, the diameter of the blast hole of the thicker plate is larger than that of the circular plate, which is not suitable for parts with higher processing accuracy requirements. Only scrap. In addition, because the oxygen environment pressure used for perforation is the same as that used for cutting, the impact of splash is large.

Pulse perforation - use a peak power pulse laser to melt or evaporate a small amount of material. Air or nitrogen is often used as auxiliary gas to reduce cavity expansion caused by exothermic oxidation, and the gas pressure is less than the oxygen pressure during cutting. Each pulse of laser only produces a small particle jet, which gradually develops in depth, so we need a few seconds for thick plate perforation. Once the perforation is completed, use oxygen instead of auxiliary gas for cutting. Such a hole diameter has little influence, and its hole quality is better than that of blasting hole. The laser used for laser cutting should not only have high output power, but also have the space-time characteristics of the beam, so the general transverse flow CO2 laser cannot meet the requirements of laser cutting. In addition, it is necessary to have a more reliable gas circuit control and management system through pulse perforation to realize the switching of different types of these gases, the gas ambient pressure and the control of perforation time.

In order to obtain high-quality cutting, we should pay attention to the transition technology from pulse punching when the workpiece is stationary to constant speed continuous cutting. Theoretically, it can usually change the cutting technical conditions of the enterprise's acceleration section, such as focal length, nozzle position, gas pressure, etc., but in fact, it is unlikely to change more than one of these conditions due to the short working time. In industrial production, it is feasible to change the average laser power by changing the pulse width, pulse frequency, pulse width and pulse frequency. The analysis of the actual research results shows that the third method has the best effect.

2. Deformation analysis of small hole cutting process
This is because Chinese machine tools (only for these high-power laser cutting machines) can not adopt the method of blasting and piercing when processing small holes, but use the method of pulse piercing (soft piercing), which makes the laser energy in China develop too intensively in a small area, scorching the non-processing enterprise area, causing hole deformation and affecting the quality of production and processing products. At present, in the process of processing, the pulse perforation (soft perforation) method should be changed to the blasting perforation (ordinary perforation) method to solve this problem. On the contrary, for a small power laser cutting machine, different pulse piercing methods should be adopted to develop a better surface finish.

3. Solution of burr problem in laser cutting low carbon steel
According to the work of CO2 laser cutting and the basic principle of teaching design, it can be concluded that the following reasons are the main reasons for the burr of machined parts caused by enterprises: the upper and lower positions of the laser focus are incorrect, so a focus position test needs to be done, and timely adjustment should be made according to the shift of the social focus; The output power of the laser is not enough. We need to check whether the staff of the laser generator can work normally. If not, observe whether the output value method of the laser technology control system button should be correct and adjust it; The linear speed of cutting is too slow, so it is necessary to increase the linear speed during actual operation risk control; The purity of cutting gas is not enough, and it is necessary to develop and provide cutting management environment gas with high quality and economy; For laser focus shift, focus position test shall be carried out, and continuous adjustment shall be made according to the shift of focus; The machine tool is unstable due to long running time. At this time, the teacher needs to shut down and restart.

4. Analysis of workpiece burr when laser cutting stainless steel and aluminum-zinc plate
For the occurrence of the above situations, first of all, it is necessary to consider the burr factor when cutting low carbon steel, but it is inevitable to simply speed up the cutting speed, because it can increase the development speed, and sometimes the situation that the plate can not be cut through. This teaching situation is particularly important when processing aluminum-zinc coated plate. At this time, other factors such as whether the nozzle should be replaced and the guide rail movement is unstable should be considered to solve the problem.

5. Analysis of laser incomplete cutting penetration
After analysis, it can be found that the following different situations are the main development conditions that affect the instability of the processing quality: the selection of the nozzle of the laser head does not match the thickness of the processing plate; The laser cutting line speed is too fast, which requires the control ability of our operating system to reduce the line speed; The nozzle induction is not allowed to lead to the laser focus position error is too large, so it is necessary to restart the detection of nozzle induction data, especially when cutting aluminum.

6. Treatment of abnormal cutting spark of low carbon steel
This development will affect the quality of products processed by cutting section finish of parts. If other parameters are normal at this time, the following conditions should be considered: the nozzle of laser head NOZZEL is lost, and the nozzle should be replaced in time. When there is no new nozzle to replace, the pressure of gas passing through the cutting management working environment should be increased; The thread at the connection between nozzle and laser head is loose. At this time, we should immediately suspend cutting, check the working status of the laser head connection, and screw on the thread again.

7. Protect the lens from water mist
In the cutting process of laser cutting machine, auxiliary gas is indispensable! Among them, oxygen and nitrogen are commonly used in our country. Of course, the higher the purity of the gas, the better the cutting quality will be. Many customers want to save the cost of air cutting, but there is always fog to protect the lens during the cutting process, and the cutting quality is poor. Why?

First of all, let's popularize the role of auxiliary gas:
1. Blow out the residue to achieve the best cutting effect.
2. Use these gases to blow away the molten metal.

Source: Qingyuan Laser