Temperature Compensation - HEIDENHAIN TNC 415 Technical Manual

1.6.5 Temperature compensation

Exact measurements of machine thermal behaviour (centre of expansion in the axes, amount of
expansion as a function of temperature) are necessary to compensate the effects of thermal
expansion.
The temperature measured through the PA 110 and Pt 100 is filed in PLC words W504 to W510 or
W472 to W478 (see Section "Analog inputs"). The thermal expansion is largely proportional to the
temperature value: you can directly determine the amount of expansion by multiplying the
temperature value by a certain factor. This calculated expansion value must be transferred through
the PLC program to the PLC word W576 to W584. As soon as the words W576 to W584 receive a
value, the "lag tracking" becomes active.
"Lag tracking" means that the actual machine position changes by a certain value per PLC cycle until
it has changed by the full value from the words W576 to W584. This does not change the value in
the actual position display. The increment of change per PLC cycle must be defined in MP4070.
W576 to W584 Lag tracking error compensation
(Compensation speed from MP4070)
Input range: +32 767 to –32 768 [Error! µm]
W576 Axis X
W578 Axis Y
W580 Axis Z
W582 4th axis
W584 5th axis
MP4070 Compensation per PLC cycle for lag tracking error compensation
Entry: 0.000 1 to 0.005 [mm]
Example:
The temperature value transmitted through the PA110 to the word W506 is multiplied by a
compensation factor (linear expansion is assumed) and is sent to the word W578 (Y axis) for "lag
tracking". The correction factor, which can only be determined through exact measurements of the
machine, is entered, for example, in MP4210.44.
.
.
.
L D944 ;correction factor from MP4210.44
;correction factor × temperature value from PA 110 (X8) = current thermal
X W506
expansion
= W578 ;value for lag tracking of the Y axis
.
.
.
4-32 TNC 407/TNC 415/TNC 425 1 Machine axes 01.98