Laser cutting machine cutting head equipment for cutting
The components of the cutting head of the laser cutting machine are: nozzle, focusing lens and focus tracking system.
nozzle
The form of the nozzle and the size of the nozzle have a great influence on the cutting quality. There are three main types of nozzles: parallel, convergent and conical. As the overview diagram. However, some foreign institutions have applied the knowledge of aerodynamics to develop a convergent-expanding nozzle. This type of nozzle can have good cutting characteristics when used in cutting. However, due to the complicated inner cavity of the nozzle, the manufacturability and fineness of the processing are limited, so that it cannot be put into industrial production.
focusing lens
Using the energy of the laser beam for cutting, the original beam emitted by the laser must be focused by a lens to form a spot with high energy density. According to Gaussian optics theory, the power density is highest at the focal point. The longer the focal length of the lens, the larger the focal spot, the lower the power density, but the larger the focal depth (the focal depth refers to the distance between two spots with a diameter change of 5% on both sides of the focal point, also known as the effective cutting range in cutting), the operating tolerance big. The effective range of a 5" lens is greater than that of a 3" lens. This is why the medium-telephoto lens is suitable for thick plate cutting, and has low requirements on the spacing stability of the tracking system, but requires high laser output power. On the contrary, the short-focus lens is only suitable for thin plate cutting below D3, and the short-focus lens has stricter requirements on the spacing stability of the tracking system, but it can greatly reduce the output power requirements of the laser.
tracking system
The focus tracking system of a laser cutting machine is generally composed of a focus cutting head and a tracking sensor system. The cutting head includes light guide focusing, water cooling, air blowing and mechanical adjustment parts; the sensor is composed of sensing elements and amplification control parts. The tracking system is completely different according to the different sensing elements. Here, there are mainly two forms of tracking system, one is the capacitive sensor tracking system, also known as the non-contact tracking system. The other is an inductive sensor tracking system, also known as a contact tracking system.
Troubleshooting and Repair
Electrodes and nozzles are the most consumed consumables in the daily operations of CNC plasma cutting machines and laser cutting machines, especially the imported electrodes and nozzles. Therefore, effectively prolonging the service life of electrodes and nozzles will greatly reduce the production cost of plasma cutting. The consumption of electrodes and nozzles is related to various factors such as air pressure, cooling water pressure, voltage, current, quality of air supply and quality of consumables. It is also necessary to pay attention to some abnormal consumption caused by machine failures. I have encountered the phenomenon that the complete set of electrodes and nozzles are frequently burned at the moment of arc striking of the cutting machine, and some are burned within 0.5~1h after cutting. These are not normal consumption.
Upon inspection, it was found that the arc generated between the electrode and the nozzle sintered the edges of the electrode and the nozzle. For this reason, measures such as using different types of electrodes and nozzles, replacing new cutting torches, adjusting gas and water pressure, etc., have some changes, but they are not significant, and sometimes they return to normal inexplicably. After repeated inspections, it was found that the fault was caused by accidental gas interruption during the cutting process. Sectional investigation found that the solenoid valve in the electric valve console lost power, which caused the gas cutoff, and the solenoid valve lost power due to the back and forth dragging of the torch trolley, resulting in poor contact of the torch control cable. Due to the short cut-off time and the good time to be measured, the fault is difficult to find. It is during this very short gas-off time that the electrodes and nozzles are burned. After re-repairing the fixed cable, the fault was eliminated.
