How to control the focus position of laser cutting machine
The laser cutting machine must first determine the position of the cutting focus at the beginning of the work. How to determine the exact focus position of the laser cutting machine? This is a topic that is more relevant to everyone. Let's introduce to you the determination of the focus position of the laser cutting machine and how to control the focus position. Focus position control technology: One of the advantages of laser cutting is the high energy density of the beam, generally 10W/cm2. Since the energy density is proportional to 4/u0026pi;d2, the focal spot diameter is as small as possible to produce a narrow slit; at the same time, the focal spot diameter is also proportional to the focal depth of the lens. The smaller the focal depth of the focusing lens, the smaller the focal spot diameter. However, there are spatters in cutting, and the lens is too close to the workpiece to damage the lens. Therefore, the focal length of 5'~7.5'' (127~190mm) is widely used in general high-power CO2 laser cutting industrial applications. The actual focal spot diameter is 0.1~0.4mm Between. For high-quality cutting, the effective focal depth is also related to the lens diameter and the material to be cut. For example, when cutting carbon steel with a 5' lens, the focal depth is within +2% of the focal length, which is about 5mm. Therefore, the focus is controlled. The position relative to the surface of the material to be cut is very important. Taking into account factors such as cutting quality and cutting speed, in principle, 6mm metal materials, the focus is on the surface; 6mm carbon steel, the focus is on the surface; 6mm stainless steel, the focus is on the surface Below the surface. The specific size is determined by experiments. There are three simple methods to determine the focus position in industrial production: (1) Printing method: make the cutting head move from top to bottom, and perform laser beam printing on a plastic plate with the smallest printing diameter (2) Inclined plate method: use a plastic plate placed obliquely at an angle to the vertical axis to pull it horizontally to find the smallest point of the laser beam as the focus. (3) Color spark method: remove the nozzle, blow air, and The pulsed laser hits the stainless steel plate to make the cutting head move from top to bottom until the largest blue spark is the focus. For the cutting machine of the flying light path, due to the divergence angle of the beam, the time length of the cutting near and far ends is different, and the focus is There is a certain difference in the size of the front beam. The larger the diameter of the incident beam, the smaller the diameter of the focal spot. In order to reduce the change in the focal spot size caused by the change in the beam size before focusing, domestic and foreign laser cutting system manufacturers provide some Special devices are available for users to choose: (1) Collimator. This is a commonly used method, that is, add a collimator at the output end of the CO2 laser for beam expansion processing, the beam diameter after expansion becomes larger, and the divergence angle It becomes smaller, so that the beam size is close to the same before focusing at the near end and the far end in the cutting working range. (2) Add an independent lower axis of the moving lens to the cutting head, which is the distance between the nozzle and the material surface (stand off). The Z axis is two independent parts. When the machine tool table moves or the optical axis moves, the beam moves from the proximal end to the distal F axis at the same time, so that the beam spot diameter remains the same in the entire processing area after the beam is focused. ( 3) Control the water pressure of the focusing lens (usually a metal reflective focusing system). If the beam size before focusing becomes smaller and the focal spot diameter becomes larger, the water pressure is automatically controlled to change the focus curvature to make the focal spot diameter smaller. (4) Add the compensation optical path system in the x and y directions on the flying optical path cutting machine. That is, when the optical path at the distal end of the cutting is increased, the compensation optical path is shortened; when the optical path at the proximal end of the cutting is reduced, the compensation optical path is increased to keep the optical path length consistent. Gaoneng Laser Equipment Manufacturing Co., Ltd. is a high-tech enterprise integrating Ru0026D, production and sales of professional laser complete equipment. Not only has it successfully developed laser equipment with advanced technology, but also used its own import and export rights to promote its products to Hong Kong, South Korea, Vietnam, Malaysia, Thailand, Australia, the United States, Japan, Germany, More than 40 countries in the world, including the Netherlands and Jordan.