Although the thermal deformation of the laser cutting machine is small, the residual internal stress of the metal sheet during the rolling and cooling process is inevitable. When cutting, the metal is rapidly expanded in the cutting direction by the local high-temperature heat source, and the surrounding mother metal limits its expansion, so that the metal at the edge of the slit generates stress. When the stress exceeds the yield strength of the metal, compressive plastic deformation occurs, which is followed by cooling. It will shrink. When it is cooled to room temperature, it will be deformed in the cutting direction due to the limitation of the surrounding base metal. At the same time, there is a certain residual tensile stress inside, which is the reason for the cutting deformation.
The laser cutting machine is a high-speed, high-temperature, high-energy plasma cutting machine combined with computer control (the combination of cutting metal sheet equipment). The working process is automatically controlled according to the pre-programmed procedures, and the processing procedure is identified. Therefore, before the processing, a reasonable cutting process is selected - the starting point, direction, sequence, speed, etc. of the cutting, which plays a role in the processing quality of the cutting part. Decisive role. In order to minimize the cutting deformation, the positioning of the metal sheet must be ensured accurately before cutting. Under normal circumstances, the arcing point of the cutting member should be at the edge of the metal sheet or in the middle of the slit of the cut workpiece. When the distance is too large, there will be no arc or arc breakage, so that the workpiece can not be cut through, resulting in waste or scrapping of the product; when the distance is too small, the nozzle and the workpiece are easily short-circuited (current does not pass the electrical appliance, directly connected to the power supply pole) The nozzle is burnt out, and the cutting process is normally destroyed.
Practice has proved that the height of the nozzle from the workpiece is generally 6-8 mm, and the air plasma cutting and water recompression plasma arc cutting nozzles can be slightly less than 6-8 mm from the workpiece height. When conditions permit, the multi-point electromagnetic platform is used for proper leveling to eliminate the residual internal stress of the metal sheet and improve the flatness of the board.