Solution for cutting circular and non-circular shapes with vibration knife control system

When using the RDD6584G or RDD6616U control system with a vibrating knife, if there is a problem of cutting circles that are not round, the following two aspects can be identified and addressed:

1. Incorrect step distance (pulse equivalent)

If the step distance (electronic gear ratio or pulse equivalent) is set incorrectly, the actual movement distance will not match the commanded distance. During circular interpolation, this deviation is amplified, resulting in elliptical shapes or dimensional inaccuracies.

Solution:
First, cut a standard square (for example, 100 mm × 100 mm) for testing.
Measure the actual dimensions in both X and Y directions.
If the proportional error is the same in both directions, recalibrate the overall step distance parameter.
If one axis shows a larger deviation, adjust the pulse equivalent of that axis individually.
After adjustment, repeat the square test until the dimensions are accurate, then test a circle again.

2. Excessive motor rigidity

Excessive motor rigidity is usually caused by overly high servo gain or an overly stiff system response. During continuous acceleration and deceleration in circular motion, vibration or oscillation may occur, forming polygonal shapes or wavy edges instead of a smooth circle.

Solution:
Reduce the servo position gain and velocity loop gain appropriately.
Lower the acceleration and deceleration parameters.
Check whether the mechanical structure is overly tight or experiencing resonance.
Observe whether performance improves at lower speeds; if it does, the issue is likely due to overly aggressive dynamic parameters.

By calibrating the step distance and optimizing dynamic parameters, circular accuracy can usually be restored.