Application of Radian laser tracker in 3D dynamic detection of large machine tools

About large multi-axis machining center
In the process of production and processing, large 5-axis and 6-axis machine tools may produce errors due to various factors, resulting in the products processed by them not meeting the expected accuracy requirements. In the process of machine tool adjustment, finding and eliminating these errors, the evaluation of dynamic 3D spatial error is very important; Compared with the traditional 21 static error detection, 3D spatial error needs to be measured with high accuracy under dynamic conditions, so it is difficult to implement using traditional detection methods.
Dynamic 3D accuracy detection&API solution
The traditional method for measuring the 21 errors of machine tools is to measure each axis (X, Y, Z) of the machine tool with a Laser Interferometer, so as to obtain the linear error, angular error of each axis and the angular error of the machine tool turntable (measured by the interferometer in cooperation with a polyhedron). However, the evaluation of these measurements is a single error obtained under static conditions, It cannot reflect the 3D spatial position error of the tool position of the 5-axis machine tool during the linkage process.

If the Laser Tracker is combined with the ordinary SMR reflecting target ball to measure the spatial position of the 5-axis machine tool, although the 3D spatial position data is obtained, due to the limited angle of the light interface of the ordinary SMR target ball, it can only obtain the static 3D spatial position data, which is also limited to the static measurement.

In order to overcome the problem of dynamic 3D spatial position accuracy measurement of large 5-axis and 6-axis machine tools, API has developed a 3D point dynamic measurement target - ActiveTarget moving target (as shown above, hereinafter referred to as AT moving target). The working principle of the AT moving target is similar to that of the traditional SMR target ball. The laser of the tracker is reflected back to the tracker through the reflector body to complete the spatial position measurement. Its special feature is that the AT target has a drive motor in the horizontal and vertical directions, and has the ability to automatically locate the reflective target, which is equivalent to a motorized SMR.
The advantage of AT moving target is that no matter what direction the laser beam is in the space and whether it moves or not, the AT moving target will always lock the laser beam. Even in the fast and arbitrary movement measurement, it will not cause "light break" with the laser tracker; Therefore, when the AT moving target is used to detect moving or rotating targets, the continuous measurement of the whole process can be automatically realized without human intervention, and the collection of 3D position coordinates can be efficiently completed under dynamic conditions.
With the advent of the AT moving target, the dynamic 3D spatial position accuracy measurement of large 5-axis and 6-axis machine tools can be realized.
Requirements and key points of 3D dynamic measurement of 5-axis machine tool
The cutter head of the 5-axis machine tool operates dynamically under the planned path, measures the position coordinates of the points under the dynamic operation path, and realizes:
1) Compare the measured dynamic point position coordinates with the theoretical running digital and analog track of the machine tool, and check its spatial error value;
2) The dynamic path point is projected to obtain the corresponding tool space swing angle value, and the dynamic swing angle error is obtained by comparing with the theoretical value;
3) . Project the dynamic track point in the three-phase limit plane to check the dynamic matching performance of each axis during operation.

Implementation steps of API scheme
The implementation steps of measuring dynamic 3D accuracy of multi-axis machine tool with Radian laser tracker and AT moving target are as follows:
① Select a stable and suitable position to put the tracker in place and start it;
② Clamp the AT movable target post handle to the tool head of the machine tool, turn it on, and connect it with the Tracker Laser;
③ The AT moving target attached to the cutter head moves according to the planned path of the machine tool, and the tracker continuously and real-time collects the points of the moving AT target position, so as to obtain the dynamic measurement 3D space point cloud;
④ Through the projection solution of the 3D points obtained by the software, the required data can be obtained to achieve the detection purpose.

conclusion
To sum up the whole detection process, the whole set of instruments and equipment is easy to arrange and operate. The measurement can be started as long as the Radian tracker and AT moving target are installed in several simple steps; The whole measurement process is automatic, smooth and without human intervention, which greatly reduces the probability of additional errors; Data analysis is efficient, fast, and reports are automatically issued, saving time and labor costs, and improving production efficiency.