In the process of laser cutting, there are many factors that cause the change of the relative position between the focus and the surface of the object to be processed, including the uneven surface of the workpiece to be processed, the clamping method of the workpiece, the geometric error of the machine tool, the deformation of the machine tool under the load, and the thermal deformation of the workpiece during the processing, which will cause the deviation between the laser focus position and the ideal given position (programming position). Some errors (such as geometric errors of machine tools) have regularity, which can be compensated by quantitative compensation method, but some errors are random errors that can only be eliminated by online detection and control. What are these errors?
1. Geometric error of workpiece
The object of laser cutting is plate or panel type part. Due to various reasons, the surface of the processing object is uneven, and the influence of the thermal effect during the cutting process will also cause the surface deformation of the sheet part. For laser processing, the surface of the panel will also be uneven during the pressing process, The position and ideal position of the laser focus and the surface of the object to be processed will change randomly.
2. Error caused by workpiece clamping device
The workpieces processed by laser cutting are placed on the needle worktable. Due to processing errors, wear between the workpieces for a long time and laser burns, the needle bed will appear uneven, which will also produce random errors in the position between the thin steel plate and the laser focus.
3. Error caused by programming
In the process of laser cutting, the processing path on the complex surface is fitted by straight lines, arcs, etc. There are certain errors between these fitting curves and the actual curves. These errors cause a certain error in the relative position of the actual focus and the surface of the processing object and the ideal programming position. Some teaching programming systems also introduce some deviations.
Laser focus position detection and control is one of the key technologies of laser cutting processing. For fast cutting processing, the focus position detection accuracy and rapidity will directly affect the control accuracy and processing quality of the focus position. Capacitive sensor has the advantages of high detection sensitivity and fast response, which can overcome its nonlinearity through the linearization of the computer system.
The special sensor structure is used to eliminate the influence of plasma cloud and slag spraying on the detection results, thus improving the application effect in the laser cutting processing system.
