Six Common Problems and Treatment Methods of Laser Cutting Machine

1. Cutting perforation technology

Any kind of thermal cutting technology, except for a few cases can start from the edge of the board, generally must wear a small hole in the board. Previously, a punch was used to punch a hole on the laser stamping compound machine, and then the laser was used to cut from the small hole. There are two basic methods of perforation for laser cutting machines without punching devices:

Blasting perforation-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 oxygen flow coaxial with the laser beam to form a hole. Generally, the size of the hole is related to the thickness of the plate. The average diameter of the blasting perforation is half of the plate thickness. Therefore, the hole diameter of the blasting perforation of the thicker plate is larger and not round. It should not be used on parts with higher processing accuracy, and can only be used on waste. In addition, since the oxygen pressure used for perforation is the same as that used for cutting, the splash is large.

Pulse perforation-the use of high peak power pulse laser to melt or vaporize a small amount of material, commonly used air or nitrogen as an auxiliary gas, in order to reduce the exothermic oxidation of the hole expansion, the gas pressure is less than the oxygen pressure when cutting. Each pulsed laser produces only a small particle jet, gradually deepening, so the thick plate perforation time takes a few seconds. Once the perforation is completed, the auxiliary gas is immediately replaced with oxygen for cutting. In this way, the perforation diameter is small, and the perforation quality is better than that of blasting perforation. The laser used for this purpose should not only have a high output power; more importantly, the temporal and spatial characteristics of the beam, so the general cross-flow CO2 laser can not meet the requirements of laser cutting. In addition, pulse perforation also need to have a more reliable gas path control system, in order to achieve the gas type, gas pressure switching and perforation time control.

In the case of pulse perforation, in order to obtain high-quality cuts, the transition technology from pulse perforation when the workpiece is stationary to the constant speed continuous cutting of the workpiece should be paid attention. Theoretically, the cutting conditions of the acceleration section can usually be changed, such as focal length, nozzle position, gas pressure, etc., but in fact, it is unlikely to change the above conditions because the time is too short. In industrial production, it is more realistic to change the average power of the laser. The specific method is to change the pulse width, change the pulse frequency, and change the pulse width and frequency at the same time. The actual results show that the third is the best.

2. Analysis of deformation of cutting small holes (small diameter and plate thickness)

This is because the machine tool (only for high-power laser cutting machine) in the processing of small holes is not to take the way of blasting perforation, but with pulse perforation (soft puncture), which makes the laser energy in a small area is too concentrated, the non-processing area is also burnt, resulting in deformation of the hole, affecting the processing quality. At this time, we should change the pulse perforation (soft puncture) method to the blasting perforation (ordinary puncture) method in the processing procedure to solve it. For the smaller power laser cutting machine is just the opposite, in the small hole processing should be taken in the way of pulse perforation to achieve better surface finish.

3. When laser cutting low carbon steel, the solution to the burr of the workpiece 

According to the working and design principle of CO2 laser cutting, the following reasons are analyzed as the main reasons for the burr of the processed parts: the upper and lower positions of the laser focus are incorrect, and the focus position test is needed to be adjusted according to the offset of the focus; The output power of the laser is not enough, and it is necessary to check whether the laser generator works normally. If it is normal, observe whether the output value of the laser control button is correct and adjust; the linear speed of cutting is too slow, and it is necessary to increase the linear speed during operation control; the purity of the cutting gas is not enough, and high-quality cutting working gas needs to be provided; the laser focus is offset, and the focus position needs to be tested and adjusted according to the offset of the focus; The instability of the machine tool due to too long running time requires shutdown and restart.

4. Analysis of burrs on workpieces when laser cutting stainless steel and aluminum-zinc plates

The emergence of the above situation, first consider the factors of burr when cutting low carbon steel, but can not simply speed up the cutting speed, because the increase in speed will sometimes appear plate cutting does not wear, this situation is particularly prominent in the processing of aluminum zinc plate. At this time, other factors of the machine tool should be considered comprehensively, such as whether the nozzle should be replaced, the guide rail movement is unstable, etc.

5. Analysis of laser incomplete cutting through state

After analysis, it can be found that the following situations are the main situations that cause unstable processing: the selection of laser head nozzle does not match the thickness of the processed plate; The laser cutting line speed is too fast, and the operation control is needed to reduce the line speed. The error of the nozzle induction to the laser focus position is too large, and the nozzle induction data needs to be re-detected, especially when cutting aluminum materials.

6. The solution of abnormal sparks when cutting low carbon steel

This situation will affect the machining quality of the cutting section finish of the part. At this time, when other parameters are normal, the following situation should be considered: the loss of the laser head nozzle NOZZEL, the nozzle should be replaced in time. In the absence of a new nozzle replacement, the cutting working gas pressure should be increased; the thread at the connection between the nozzle and the laser head is loose. At this time should immediately stop cutting, check the laser head connection status, re-thread.