The design of the internal gas flow channels of the laser cutting head has a decisive impact on the cutting effect of the auxiliary gas. Its core objectives are to achieve uniform gas pressure distribution, precise flow rate control, and effective turbulence suppression, thereby ensuring efficient removal of molten material and preventing airflow interference with optical components. The design of the gas flow channels requires comprehensive optimization of multiple aspects, including the inlet structure, internal gas channel layout, air outlet distribution, and nozzle outlet matching.
The gas inlet is the primary channel for auxiliary gas to enter the laser cutting head, and its design must balance flow rate requirements and pressure stability. The inlet structure typically adopts a tapered design, increasing gas velocity through a gradually narrowing channel while reducing pressure loss. A filter device must also be installed at the inlet to prevent impurities from entering the flow channel and avoiding blockage or scratches to the internal cavity. Furthermore, the connection between the inlet and the external gas source must be reliably sealed to prevent gas leakage that could cause pressure fluctuations and affect cutting quality.
The internal gas channels of the laser cutting head are a critical area for gas pressure diffusion and homogenization. Traditional straight gas channels tend to cause gas to form vortices at corners, resulting in uneven pressure distribution. Modern designs often employ spiral or annular air channels, guiding gas along a specific path of rotation and diffusion to eliminate localized pressure dead zones. This design allows the gas to form a stable laminar flow state before reaching the blowing port, laying the foundation for subsequent uniform injection. Simultaneously, the inner wall of the air channel needs to be polished to reduce roughness, decrease frictional resistance during gas flow, and further improve pressure transmission efficiency.
The layout of the blowing ports directly affects the uniformity of gas injection. Multi-blowing-port designs, by distributing high-pressure gas to multiple outlets, avoid turbulence problems caused by excessive flow at a single outlet. The blowing ports are typically evenly distributed circumferentially along the internal cavity, ensuring that gas is injected synchronously from multiple directions, forming an enveloping airflow. This design ensures that the molten material receives uniform blowing force in all directions, preventing slag buildup or burrs caused by insufficient localized force. Furthermore, the diameter of the blowing ports needs to be precisely calculated based on the required gas pressure and flow rate; too large a diameter will lead to airflow dispersion, while too small a diameter may cause blockage.
The internal cavity is the core area for gas mixing and flow stabilization. After high-pressure gas is injected into the cavity from the air inlet, its speed and direction need to be adjusted and calibrated here. The cavity structure typically employs an expansion-contraction design. First, the gas velocity is reduced through the expansion section to decrease turbulence intensity, and then the airflow is refocused through the contraction section to increase the jet force. Some high-end designs also incorporate baffles or honeycomb structures within the cavity to further refine the airflow and eliminate micro-vortices. These measures ensure that the gas forms a stable and uniform turbulence upon exiting the cavity, providing sufficient momentum to remove molten material without affecting cutting accuracy due to excessive turbulence.
The nozzle outlet is the direct interface between the gas flow channel and the cutting environment, and its design must be closely integrated with the internal flow channel. The diameter, shape, and distance of the nozzle outlet from the workpiece all affect the actual effect of the airflow. An excessively large outlet diameter leads to airflow dispersion, reducing the blowing force per unit area; an excessively small diameter may damage the workpiece surface due to overly concentrated airflow. Common nozzle shapes include conical or Laval nozzles. The former is suitable for subsonic airflow, while the latter can achieve supersonic jetting through a contraction-expansion structure, significantly improving cutting efficiency. Furthermore, the distance between the nozzle and the workpiece needs precise control. Too much distance will cause airflow diffusion, while too little distance may cause airflow rebound, interfering with the cutting process.
The design of the gas flow channel also needs to consider the type of auxiliary gas and the characteristics of the material being cut. Oxygen cutting requires enhancing the oxidation reaction in the airflow, so the flow channel design needs to focus more on pressure transmission efficiency to ensure that oxygen can fully participate in combustion. Nitrogen cutting, on the other hand, requires focusing on suppressing oxidation, so the flow channel design needs to pay more attention to the purity and stability of the airflow to prevent air from mixing in and causing oxidation of the cut surface. For materials of different thicknesses, the gas velocity and pressure also need to be dynamically adjusted, and the flow channel design needs to have a certain degree of flexibility to adapt to diverse cutting needs.
The design of the internal gas flow channel of a laser cutting head is a comprehensive engineering project involving fluid mechanics, materials science, and precision manufacturing. By optimizing key aspects such as the inlet structure, internal gas channels, air outlet layout, cavity flow stabilization, and nozzle outlet, the cutting effect of the auxiliary gas can be significantly improved, achieving higher precision and higher efficiency laser processing.
