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 of the focusing light path. For laser cutting pipes, to obtain high-quality slitting, it is necessary to focus the beam with small spot diameter and high power. This allows the laser generator to output low order modes. In the process of tube laser cutting, in order to obtain a relatively small beam focusing diameter, the transverse mode order of the laser is small, preferably the basic mode. The cutting head of the laser cutting equipment is equipped with a focusing lens. After the laser beam is focused through the lens, a small focusing spot can be obtained, so that high-quality pipe cutting can be carried out.
Trajectory control of cutting head
In pipe cutting, the pipe to be processed belongs to a spatial curved surface with complex shape. It will be difficult to program and process with conventional methods, which requires the operator to select the correct processing path and appropriate reference point according to the requirements of the processing technology, record the feed of each axis and the coordinate value of the reference point with the NC system, and then use the spatial straight line and arc interpolation function of the laser cutting system, Record the coordinate value of the machining process and generate the machining program.
Automatic control of laser cutting focus position
How to control the focus position of laser cutting is an important factor affecting the cutting quality. It is one of the key technologies of laser pipe cutting to keep the vertical direction of 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 flexible, and the position of the focus can be known as the palm of your hand, thus avoiding the collision between the cutting head and the cutting pipe or other objects during the processing.
Influence of main process parameters
(1) Influence of optical power.
For the continuous wave output laser generator, the size of laser power will have an important impact on laser cutting. Theoretically, the higher the laser power of the laser pipe cutting equipment is, the higher the cutting speed can be obtained. However, considering 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 will affect the focusing of the laser beam. In actual processing, we often choose to make the focus obtain the highest power density when the power is less than the maximum power, so as to ensure the efficiency and quality of the entire laser cutting.
(2) The influence of cutting speed.
When laser cutting pipes, it is necessary to ensure that the cutting speed is within a certain range in order to obtain better cutting quality. If the cutting speed is too slow, too much heat will accumulate on the pipe surface, the heat affected zone will become larger, and the kerf will become wider. The discharged hot melt material will burn the cut surface, making the cut surface rough. When the cutting speed is increased, the average circumferential slit width of the pipe becomes smaller, and the smaller the diameter of the pipe to be cut, the more obvious this effect is. As the cutting speed increases, the laser action time shortens, the total energy absorbed by the pipe decreases, the front end temperature of the pipe decreases, and the kerf width decreases. If the cutting speed is too fast, the pipe cannot be cut through or cut continuously, which affects the entire cutting quality.
(3) Impact of pipe diameter.
When laser cutting pipe, the characteristics of 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 tube laser cutting equipment will increase the slit width as the pipe diameter increases while the process parameters remain unchanged.
(4) Type and pressure of auxiliary gas.
When cutting non-metallic and some metal pipes, compressed air or inert gas (such as nitrogen) can be used as auxiliary gas. While for most metal tube laser cutting, active gas (such as oxygen) can be used. After determining the type of auxiliary gas, it is very important to determine the pressure of auxiliary gas. When cutting pipes with small wall thickness at a higher speed, the pressure of auxiliary gas shall be increased to prevent slag from hanging on the cut; When the pipe wall thickness is large or the cutting speed is slow, the pressure of the auxiliary gas should be appropriately reduced to prevent the pipe from being cut through or being cut continuously.
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Key Technologies of Laser Pipe Cutting System
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