Interpolatory Compensation; General - Siemens SINUMERIK 808D Function Manual

11.3

Interpolatory compensation

11.3.1

General

Terminology
Compensation value: The difference between the axis position measured by the position actual-value encoder and the
required programmed axis position (= axis position of the ideal machine). The compensation value is often also referred to
as the correction value.
Interpolation point: A position of the axis and the corresponding offset value.
Offset table: Table containing interpolation points
Compensation table
Because dimensional deviations between the leadscrew pitch and the measuring system directly affect the accuracy of
workpiece machining, they must be compensated for by the relevant position-dependent compensation values. The
compensation values are derived from measured error curves and entered in the control in the form of compensation tables
during installation. A separate table must be created for each compensation relation.
The compensation values and additional table parameters are entered in the compensation tables using special system
variables.
Entry of compensation table
Compensation tables can be loaded to the backed up NC user memory by two different methods.
● The compensation values are loaded when an NC program tables is started. with the compensation
● The compensation values can also be loaded by transferring the tables from a personal computer (PC) through the serial
interface on the HMI.
Note
The compensation tables can be output via the serial interface on the HMI through the following operations, and then
loaded back following editing:
+ ->
Linear interpolation between interpolation points
The traversing path to be compensated - defined using the start and end positions - is divided up into several (number
depends on error curve shape) path segments of equal size (see figure below). The actual positions that limit these sub-
paths are designated "interpolation points". A compensation value must be entered for each interpolation point (actual
position) during commissioning. The compensation value applied between two interpolation points is generated on the basis
of linear interpolation using the compensation values for the adjacent interpolation points (i.e. adjacent interpolation points
are linked along a line).
Linear interpolation between the interpolation points:
Function Manual
01/2017
-> -> NCK/PLC data: Leadscrew error compensation
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