A shortcut to solve the focus error

Little knowledge of laser cutting - a shortcut to solve the focus error

In the process of laser cutting, there are many factors that cause the relative position

 between the focus and the surface of the processed object to change. Thermal deformation during processing will cause the laser focus position to deviate from the ideal given position (programmed position).

Why do focus errors occur

Some errors (such as geometric errors of machine tools) are regular and can be compensated by quantitative compensation methods, but some errors are random errors that can only be eliminated through online detection and control.

1. Workpiece geometric error

   
   

The object of laser cutting is plate or cover type parts. Due to the influence of various reasons, the surface of the processing object has undulations, and the influence of thermal effects during the cutting process will also cause surface deformation of thin plate parts. For 1D laser processing, Surface unevenness will also occur during the pressing and forming process of the cover, all of which will cause random changes in the position and ideal position of the laser focus and the surface of the processed object.

2. The error generated by the workpiece clamping device

The workpiece processed by laser cutting is placed on the needle-shaped worktable. Due to processing errors, long-term wear and tear between the workpiece and laser burns, the needle bed will appear uneven, and this unevenness will also cause gaps between the thin steel plate and the laser focus. random error in the position.

3. Programming errors

In the laser cutting process, the processing trajectory 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 make the relative position of the actual focus and the surface of the processing object consistent with the ideal programming There is a certain error in the position, and some teaching programming systems will also have some deviation.

After years of development in the laser industry, there has been a relatively complete solution to the above-mentioned focus errors. The laser focus can be adjusted by manually adjusting the mechanical device on the laser head. In addition, the current laser head with automatic focusing function is relatively mature, and combined with a professional numerical control system, it can help customers solve the problem of errors in laser cutting.

How to adjust the focus position

The online detection and control system of laser cutting focus position is composed of controller, detection system, execution device and other parts. According to the relationship between the focus position detection control system and the system, the focus position detection control system is divided into two types: independent type and integrated type, also called manual focus and automatic focus.

1. Manual focus

The manual focusing focus position detection and control system uses a separate coordinate axis for focus position error compensation control. The mechanical structure is simple and the cost is low, but it can be used in conjunction with various numerical control systems and laser cutting machine tools.

2. Automatic focus

Auto-focusing uses the composite movement of one feed axis or multiple feed axes of the laser cutting machine itself to compensate for focus position errors. This method has a relatively complex structure and high cost, but it is simple to operate and easy to adjust, and it is required to be used in conjunction with a numerical control system. On the CNC software interface that supports automatic focusing, by adjusting the parameters, the laser head can be controlled to adjust the focus by itself. This reduces human intervention and enables more precise focus placement.