HEIDENHAIN TNC 306 Technical Manual - Manual (Page 143)

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TNC 406/TNC 306 3 Servo positioning of the NC-axes 4-43
MP1020 Manual feed
Entry range 80 to 30 000 [mm/min]
MP1020.0 Manual feed X axis
MP1020.1 Manual feed Y axis
MP1020.2 Manual feed Z axis
MP1020.3 Manual feed axis 4
MP1020.4 * Manual feed axis 5
Servo accuracy
The internal servo accuracy and the display step of the control is always 1 µm.
The control must be able to generate at least one voltage step per 1 µm position deviation.
Calculation of the smallest voltage step
The control produces an analog voltage of 0 to 10 V. In the TNC the 10 V analog potential is
produced by a 14-bit ADC, giving 16 384 divisions. The resulting smallest potential step is 0.6 mV.
Potential steps per µm position deviation . As described above, moving with rapid traverse (MP1010)
results in a certain lag distance s
a
. The rapid traverse rate is reached at a definite voltage (MP1050).
So it is possible to calculate a definite potential
∆U per µm of position deviation (lag).
∆U = MP1050 [mV] / s
a
[µm]
If
∆U is divided by the smallest voltage step which can be produced (0.6 mV), the result is the
number of voltage steps which are produced per µm position deviation.
for the TNC 306:
n =
∆U [mV]/0.6 [mV]
Example:
k
v
= 2 rapid traverse 5 000 [mm/min], U = 9 [V]
s
a
=
5 000 [
µm]
2
= 2 500 [µm]
∆U =
9 000 [mV]
2 500 [
µm]
= 3.6 [mV/µm]
n =
3.6 [mV/
µm]
0.6 [mV]
= 6 steps/µm position deviation
* only TNC 406