Siemens SINUMERIK 840D sl Function Manual page 419

Commissioning stage 2: Friction compensation with adaptation
Application
Whenever friction compensation depends on the acceleration and the required results
cannot be obtained with constant injection amplitude, adaptation must be used.
In order to obtain optimum compensation over the whole of the working range of the friction
feedforward control where high demands are made on accuracy, the acceleration
dependency of the compensation value must be calculated. To achieve this, the dependency
must be measured at various points in the working range between acceleration zero and the
maximum planned acceleration. The adaptation characteristic derived from the
measurement results is then entered in the above machine data axis-specifically.
1. Calculate the adaptation characteristic
For different radii and velocities ...
1. ... it is necessary to determine the required injection amplitudes,
2. ... it is necessary to check the compensatory effect of the injection amplitudes using the
3. ... it is necessary to log the optimum amplitudes.
The adaptation characteristic is defined completely by the settings of the parameters
specified in Section "Conventional friction compensation". However, many more measured
values must be obtained for checking purposes. It must be ensured that there is a sufficiently
large number of interpolation points for small radii at high speed. The size of the curves must
be obtained by plotting.
2. Determining acceleration values
For circular movements, the axial acceleration values are calculated with radius r and the
traversal velocity v according to the formula
a = v
The velocity and thus also the axial acceleration value a can be varied easily by means of
the feedrate override switch.
The acceleration values a
relevant machine data in compliance with condition a
MD32550 $MA_FRICT_COMP_ACCEL1(adaptation acceleration value 1)
to
MD32570 MA_FRICT_COMP_ACCEL3 (adaptation acceleration value 3)
If the curve is wrongly parameterized, the alarm 26001 "Parameterization error for friction
compensation" is output.
Extended Functions
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
circularity test,
/r
2
5.6 Friction compensation (quadrant error compensation)
, a and a for the adaptation characteristic must be entered in the
1 2 3
K3: Compensation
< a < a :
1 2 3
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