Analysis of laser incomplete cutting through state
Blasting perforation-the material forms a pit in the center after continuous laser irradiation, and then the molten material is quickly removed to form a hole by the oxygen flow coaxial with the laser beam. Generally, the size of the hole is related to the plate thickness. The average diameter of the blasting hole is half of the plate thickness. Therefore, the blasting hole diameter of the thicker plate is larger and not round. It is not suitable for use on parts with high machining accuracy. On the waste. In addition, since the oxygen pressure used for perforation is the same as that used for cutting, the splash is larger.
Pulse perforation——Using high peak power pulse laser to melt or vaporize a small amount of material. Air or nitrogen is often used as auxiliary gas to reduce the expansion of the hole due to exothermic oxidation. The gas pressure is lower than the oxygen pressure during cutting. Each pulse laser only produces small particle jets, which gradually penetrate deeper, so it takes a few seconds to perforate thick plates. Once the perforation is completed, immediately change the auxiliary gas to oxygen for cutting. In this way, the perforation diameter is smaller, and the perforation quality is better than blast perforation. For this reason, the laser used should not only have a higher output power; more importantly, the time and space characteristics of the beam, so the general cross-flow CO2 laser cannot meet the requirements of laser cutting. In addition, pulse perforation requires a more reliable gas path control system to realize the switching of gas types, gas pressure and perforation time control.
1. Analysis of the deformation of small holes (small diameter and thickness)
This is because the machine tool (only for high-power laser cutting machines) does not use blasting perforation when processing small holes, but uses pulse perforation (soft puncture), which makes the laser energy too concentrated in a small area. The non-processing area is also scorched, resulting in hole deformation and affecting processing quality. At this time, we should change the pulse perforation (soft puncture) method to the blast perforation (ordinary puncture) method in the processing program to solve it. The opposite is true for laser cutting machines with lower power. Pulse perforation should be used to obtain better surface finish when processing small holes.
2. The solution to the burrs on the workpiece when laser cutting mild steel
According to the working and design principles of CO2 laser cutting, the analysis shows that the following reasons are the main reasons for the burrs of the processed parts: the upper and lower positions of the laser focus are not correct, and the focus position test needs to be done, and the focus is adjusted according to the offset of the focus; The output power of the laser is not enough. It is necessary to check whether the laser generator is working normally. If it is normal, observe whether the output value of the laser control button is correct and adjust it; the cutting line speed is too slow, and the line speed needs to be increased during operation control; The purity of the cutting gas is not enough, it is necessary to provide high-quality cutting working gas; the laser focus shift, the focus position test needs to be done, and the adjustment is made according to the shift of the focus; the instability of the machine running time is too long, and it needs to be shut down. Restart.
3. Analysis of burrs on the workpiece during laser cutting of stainless steel and aluminum-zinc plate
For the above situations, first consider the factors of burrs when cutting low-carbon steel, but you cannot simply increase the cutting speed, because increasing the speed sometimes causes the sheet to be cut without penetration, which is particularly prominent when processing aluminum-zinc sheets . At this time, other factors of the machine tool should be taken into consideration to solve the problem, such as whether the nozzle should be replaced, and the guide rail movement is unstable.
4. Analysis of the state that the laser is not completely cut through
After analysis, it can be found that the following situations are the main reasons for processing instability: the choice of laser head nozzle does not match the processing thickness; the laser cutting line speed is too fast, and operation control is required to reduce the line speed; in addition, special Note that the laser lens with 7.5" focal length needs to be replaced when the L3030 laser cutting machine is cutting carbon steel plates above 5mm.