The key technology of metal laser tube cutting machine tube laser cutting system
Metal pipes are widely used in aircraft manufacturing, construction machinery, automobile industry, petrochemical industry, agriculture and animal husbandry machinery and other industries. Due to different application scenarios, parts of different shapes and sizes need to be processed to meet the needs of different industries. Laser processing technology is especially suitable for the processing of various metal pipes. The pipe laser cutting system has the characteristics of high flexibility and high automation, and can realize the production mode of small batches and varieties of different materials.
The key technology of tube laser cutting system
Light guide focusing system
The function of the light guide focusing system is to guide the beam output by the laser generator to the cutting head that focuses the light path. For laser cutting pipes, in order to obtain high-quality slits, the focused spot diameter of the focused beam needs to be small and the power is high. This allows the laser generator to output low-order modes. In order to obtain a relatively small beam focusing diameter during tube laser cutting, the order of the transverse mode of the laser is smaller, preferably the fundamental mode. The cutting head of the laser cutting equipment is equipped with a focusing lens. After the laser beam is focused by the lens, a small focusing spot can be obtained, so that high-quality pipe cutting can be performed.
Trajectory control of cutting head
In pipe cutting, the pipe to be processed is a space curved surface with a complex shape. If it is programmed and processed by conventional methods, it will be difficult to process. This requires the operator to select the correct processing path and appropriate reference point according to the processing technology requirements. Use the numerical control system to record the feed situation of each axis and the coordinate value of the reference point, and then record the coordinate value of the processing process and generate the processing program through the spatial linear and circular interpolation functions of the laser cutting system.
Automatic control of laser cutting focus position
How to control the laser cutting focus position is an important factor affecting the cutting quality. It is one of the key technologies for laser cutting pipes to keep the vertical direction of the focus relative to the workpiece surface unchanged through automatic measurement and control devices. Through the integration of the control of the laser focus position and the linear axis (X-Y-Z) of the laser processing system, the movement of the laser cutting head is more light and flexible, and the position of the focus point can be well known, avoiding the cutting head in the processing process and cutting the pipe. Or other objects collide.
Influence of main process parameters
Effect of Optical Power
For laser generators with continuous wave output, the size of laser power will have an important impact on laser cutting. In theory, the higher the laser power of the laser cutting pipe equipment, the higher the cutting speed can be obtained, but combined with the characteristics of the pipe itself, the maximum cutting power is not the best choice. When the cutting power is increased, the mode of the laser itself changes, which affects the focusing of the laser beam. In actual processing, we often choose to let the focus get the highest power density when the power is less than the maximum power, so as to ensure the efficiency and cutting quality of the entire laser cutting.
The effect of cutting speed
When laser cutting pipes, it is necessary to ensure that the cutting speed is within a certain range to obtain better cutting quality. If the cutting speed is too slow, too much heat will accumulate on the surface of the pipe, the heat-affected zone will become larger, the kerf will become wider, and the discharged hot-melt material will burn the kerf surface, making the kerf surface rough. When the cutting speed is increased, the average slit width around the circumference of the pipe becomes smaller, and the smaller the diameter of the pipe being cut, the more obvious the effect. As the cutting speed increases, the laser action time is shortened, the total energy absorbed by the pipe decreases, the temperature at the front end of the pipe decreases, and the slit width decreases. Thus affecting the overall cutting quality.
The effect of pipe diameter
When laser cutting pipes, the characteristics of the pipe itself will also have a great impact on the processing process. For example, the diameter of the round pipe has a significant impact on the processing quality. Through the research on laser cutting thin-walled seamless steel pipes, it is found that the diameter of the laser cutting pipe equipment continues to increase when the process parameters remain unchanged. The width will also keep increasing.
Type and pressure of auxiliary gas
Compressed air or an inert gas such as nitrogen can be used as an auxiliary gas when cutting non-metallic and some metal pipes, while a reactive gas such as oxygen can be used for most metal pipes. After determining the type of auxiliary gas, it is also extremely important to determine the pressure of the auxiliary gas. When cutting pipes with a small wall thickness at a high speed, the pressure of the auxiliary gas should be increased to prevent slag hanging on the incision; when the cutting pipe wall thickness is large or the cutting speed is slow, the auxiliary gas should be appropriately reduced pressure to prevent the pipe from being cut through or cut continuously.
The position of the beam focus is also important when laser cutting tubes. When cutting, the focus position is generally at the surface position of the cutting pipe. When the focus is in a better position, the kerf is the smallest, the cutting efficiency is the highest, and the cutting effect is also the best.
