Siemens SINUMERIK 840C - Manual (Page 963)

12 Functional Descriptions 09.95
12.19.4 Temperature compensation TC
The effects of both errors are cumulative and mutually superimposed so that the approximation
with regards to actual value influence is as follows:
-x +x Reference
point
Error
(comp. value)
Error curve
Approximated
error line
ß
P
0
K
TC
P
x
0
K
TCabs
Please note the following definitions:
K
TC
: Temperature compensation value for axis i at position P
x
K
TCabs
: Position-independent TC value for axis i
P
x
: Actual position of axis i
P
0
: Reference position for axis i
tanß : Coefficient for position-dependent TC
(depends on temperature and coefficient of linear expansion of machine).
K
TC
- K
TCabs
tanß = ––––––––––––––
P
x
- P
0
Caution:
Reference point P
0
must not coincide with the axis zero point.
The approximated error line of the axis is now used by the control for temperature
compensation of this axis.
Since the error line applies only to the current temperature value, the parameters of new error
lines occurring as a result of increases or drops in temperature must be transferred to the NC
again.
Only in this way can it be ensured that varying degrees of thermal expansion are compensated
in the correct way.
12–188 © Siemens AG 1992 All Rights Reserved 6FC5197- AA50
SINUMERIK 840C (IA)