(1) Acceleration control function before interpolation and speed feedforward channel control.
The five-axis linkage cnc machine tool is characterized by high precision of contour wheel copper machining. In the high-speed and high-precision surface processing, the acceleration control function before interpolation is very important, and in the acceleration control function before interpolation, the speed loop of each feed axis can adopt a higher speed gain, and the system control accuracy is great Improve; especially for B and C axis (A and C pendulum axis) this is desirable.
The acceleration control function before interpolation and the speed feedforward channel control can be used at the same time. The three points to note are that the acceleration after interpolation cannot be too high; the conversion speed between the second blocks cannot be too fast; the third processing The curvature of the profile wheel does not change much.
In the look-ahead control mode (Look-ahead control mode), the main function of the pre-interpolation acceleration control function is to reduce vibration, because the preferred factors for the look-ahead function are contour processing accuracy and processing time. Some CNC systems are equipped with a dedicated look-ahead function to interpolate the acceleration parameters before interpolation, such as FANUC Cnc Machining centers.
It must also be considered that the execution time of the smallest program segment has enough time for brass stamping blanks preprocessing the follow-up program to ensure the continuity of the speed of the program segment conversion.
(2) Selection of processing program control type
With the emergence of five-axis control functions, five-axis linkage (mainly five-axis interpolation) has exceeded the meaning of feed axis interpolation. The C and B axis (or A axis) can be set to the maximum orientation axis (RTCP) of the machine tool according to the type of machine tool. The geometric dimensions of the C axis axis to the B axis axis and the maximum axis axis to the B axis axis are both As dynamic compensation appears in the interpolation cycle, it reduces the mechanical error caused by the disjoint or non-orthogonal axis of the C axis and the B axis when the C and B axis rotate, and improves The contour accuracy of the workpiece processed by the five-axis linkage is improved, which was not possible with the five-axis linkage in the past.
For example: G1G91X1.605Y-0.727Z-0.671B1.100C -1.362F10000 a processing program.
Undefined RTCP five-axis control, CNC interpolation calculator distributes feed, acceleration and speed to X, Y, Z, C and B axis at the same time, X, Y and Z programming path is non-processing path, C and B axis rotation Change the position of the tool tip directly. The working coordinates are defined by the intersection of the C axis and the B axis, the *** axis and the B axis. There is no dynamic compensation for the geometric dimensions of the axis, and the mechanical error is brought into the processing.
After defining the RTCP five-axis control, the C and B axis rotation is decoupled from the machining path. The programmed paths of X, Y and Z are the machining paths, and the C and B axis rotation only changes the direction of the *** axis. After the geometrical dimension of the axis is dynamically compensated, the working coordinates are corrected, which eliminates the mechanical error.