Laser cutting processing is to replace the traditional mechanical knife with an invisible beam. It has the characteristics of high precision, fast cutting, not limited to cutting patterns, automatic typesetting, saving materials, smooth cuts, and low processing costs. It will be gradually improved or replaced. Traditional metal cutting process equipment.
The mechanical part of the laser cutter head has no contact with the workpiece, and will not scratch the surface of the workpiece during work; the laser cutting speed is fast, the incision is smooth and flat, and generally does not require subsequent processing; the cutting heat affected zone is small, the plate deformation is small, and the slit is narrow; The incision has no mechanical stress, no shearing burr; high processing accuracy, good repeatability, and no damage to the surface of the material; CNC programming, can process any plan, can cut a large area of the whole board, does not need to open a mold, economical and time-saving.
In the laser cutting machine, several key technologies must be mastered and solved for parts with higher cutting precision or larger thickness. Focus position control is one of them. One of the advantages of laser cutting is that the energy density of the beam is high, so the focal spot diameter is as small as possible in order to produce a narrow slit. Because the smaller the focal depth of the focusing lens, the smaller the focal spot diameter. For high-quality cutting, the effective focal depth is also related to the lens diameter and the material being cut. Therefore, it is important to control the position of the focus relative to the surface of the material to be cut.
Since the laser power density has a great influence on the cutting speed, the choice of lens focal length is an important issue. After the laser beam is focused, the spot size is proportional to the lens focal length. After the beam is focused by a short focal length lens, the spot size is very small, and the power density at the focal point is very high, which is very beneficial for material cutting; but its disadvantage is that the depth of focus is very short and the adjustment margin Small, generally suitable for high-speed cutting of thin materials. Since the long focal length lens has a wider focal depth, as long as it has sufficient power density, it is more suitable for cutting thick workpieces.
After determining which focal length lens to use, the relative position of the focal point and the surface of the workpiece is particularly important to ensure the cutting quality. Due to the high power density at the focus, in most cases, the focus position is just on the surface of the workpiece during cutting, or slightly below the surface. In the whole cutting process, ensuring the constant relative position of the focus and the workpiece is an important condition for obtaining stable cutting quality. Sometimes, the lens is heated due to poor cooling during operation, which causes the focal length to change, which requires timely adjustment of the focal position.
When the focus is in the right position, the slit is small, the efficiency is high, and the cutting speed can obtain good cutting results. In most applications, the beam focus is adjusted to just under the nozzle. The distance between the nozzle and the surface of the workpiece is generally about 1.5 mm.
In the process of laser application, problems such as focusing are often encountered. There are three common easy methods to determine the focus position:
(1) Inclined plate method: Use a plastic plate placed obliquely at an angle to the vertical axis to pull it horizontally, looking for a smaller spot of the laser beam as the focus.
(2) Printing method: The cutting head is moved from top to bottom, and laser beam printing is performed on the plastic plate, with the smaller printing diameter as the focus.
(3) Blue spark method: remove the nozzle, blow air, hit the pulse laser on the stainless steel plate, make the cutting head move from top to bottom, until the blue spark is the focus.