Solutions to Common Problems When Laser Cutting Sheet Metal
In the process of laser cutting sheet metal, it is inevitable to encounter various problems. Our technicians have provided the following solutions for common problems.
1. Analysis of the deformation of small holes in cutting processing
When processing small holes, the high-power laser cutting machine adopts the method of pulse perforation (soft puncture), which makes the laser energy too concentrated in a small area, and burns the non-processing area, causing the deformation of the hole and affecting the processing quality. At this time, we should change the pulse perforation (soft perforation) method to the blast perforation (ordinary perforation) method in the processing program to solve it. For the laser cutting machine with lower power, it is just the opposite. When processing small holes, pulse perforation should be adopted to obtain better surface finish.
2. The solution to the burr on the workpiece
According to the working and design principle of CO2 laser cutting, it is concluded that the following reasons are the main reasons for the burrs of the processed parts.
1) The upper and lower positions of the laser focus are not correct, the focus position test needs to be done, and the adjustment is made according to the offset of the focus;
2) If the output power of the laser is not enough, it is necessary to check whether the laser generator is working properly. If it is normal, observe whether the output value of the laser control button is correct and adjust it;
3) The cutting line speed is too slow, and it is necessary to increase the line speed during operation control;
4) The purity of the cutting gas is not enough, and it is necessary to provide high-quality cutting working gas;
5) If the laser focus is shifted, it is necessary to test the focus position and adjust it according to the offset of the focus;
6) If the machine tool runs for too long, the instability occurs, and it needs to be shut down and restarted at this time.
3. The laser is not completely cut through
After analysis, it can be found that the following situations are the main situations that cause processing instability:
1) The selection of the nozzle of the laser head does not match the thickness of the processed plate;
2) The laser cutting line speed is too fast, and operation control is required to reduce the line speed;
3) In addition, it is also necessary to pay special attention to the need to replace the 7.5″ focal length laser lens when the L3030 laser cutting machine cuts carbon steel plates above 5mm.
4. Solutions to abnormal sparks when cutting mild steel
The occurrence of abnormal sparks will affect the quality of the cut surface finish of the part. At this time, when other parameters are normal, the following situations should be considered:
1) If the nozzle of the laser head is damaged, the nozzle should be replaced in time. In the case of no new nozzle replacement, the cutting working gas pressure should be increased;
2) The thread at the connection between the nozzle and the laser head is loose. At this time, the cutting should be suspended immediately, the connection status of the laser head should be checked, and the threads should be re-threaded.
5. Selection of puncture point during laser cutting
The working principle of the laser beam during laser cutting is as follows: during the processing, the material is irradiated by a continuous laser to form a pit in the center, and then the molten material is quickly removed by the working airflow coaxial with the laser beam to form a hole. This hole is similar to the threading hole for wire cutting. The laser beam uses this hole as the starting point for contour cutting. Usually, the running direction of the laser beam in the flying light path is perpendicular to the tangent direction of the cutting contour of the machined part.
In a word, when the laser beam starts to penetrate the steel plate and enters the part contour cutting, its cutting speed will have a great change in the vector direction, that is, the 90° rotation of the vector direction, which is determined by the tangent line perpendicular to the cutting contour. The direction is turned to coincide with the tangent of the cutting contour, that is, the included angle with the contour tangent is 0°. This will leave a relatively rough cutting surface on the cutting section of the material to be processed. This is mainly due to the rapid change of the vector direction of the laser beam as it moves in a short period of time. Therefore, it is necessary to pay attention to this aspect when using laser cutting to process parts.
Generally, when the design part has no roughness requirements for the surface cutting fracture, it is possible to do no manual processing during the laser cutting programming, and let the control software automatically generate the puncture point; however, when the design has a higher roughness for the cutting section of the part to be processed When requested, pay attention to this issue. It is usually necessary to manually adjust the starting position of the laser beam when programming the laser cutting program, that is, manual control of the puncture point. It is necessary to move the puncture point originally generated by the laser program to the required reasonable position to meet the requirements for the surface accuracy of the machined parts.