Siemens SINUMERIK 840D sl Function Manual page 448

Compensations (K3)
Circularity test
5.8 Circularity test
Function
One of the purposes of the circularity test is to check the contour accuracy obtained by the
friction compensation function (conventional or neural QEC). It works by measuring the
actual positions during a circular movement and displaying the deviations from the
programmed radius as a diagram (especially at the quadrant transitions).
Procedure
The circle contour for the axes involved is specified by an NC program. To simplify the
circularity test as much as possible for the commissioning engineer, an NC program is
provided as a reference example for the circularity test motion (file QECTEST.MPF on the
diskette with the basic PLC program). The commissioning engineer must adapt this NC
program to his application.
Several measurements must be made during the circularity test with different acceleration
values to ascertain whether the learnt compensation characteristic (for neural QEC) or the
defined compensation values (for conventional QEC) meet the requirements.
The circular movement can easily be made with different accelerations if you change the
feedrate using the feedrate override switch without changing circular contour. The real
feedrate must be taken into account in the measurement in the input field "feedrate".
The circle radius chosen must be typical of machining operations on the machine (e.g. radius
in the range 10 to 200 mm).
For the duration of the circular movement, the position actual values of the axes are
recorded and stored in a "trace" in the passive file system. The circularity test is therefore
purely a measuring function.
Parameterization of circularity test
You select in this menu the names or numbers of the axes with which the circle is traversed
and whose actual position data must be recorded. No check is made to find out whether the
selected axes match the axes programmed in the NC part program.
The parameter settings in the input fields "Radius" and "Feed" must correspond to the values
from the part program that controls the circular motion of the axes, taking account of the feed
override switch setting. No check is made to see whether the values in the part program
(including feedrate override) and the input values match.
The "Measuring time" display field shows the measuring time calculated from the "Radius"
and "Feed" values for recording the position actual values during the circular movement.
If only parts of the circle can be represented (i.e. measuring time too short) the measuring
time can be increased in the menu by reducing the feed value. This also applies if the
circularity test is started from the stationary condition.
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Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Extended Functions