Function Manual
01/2017
139
Measurement accuracy and functional testing
13.4.1
Measuring accuracy
Accuracy
The propagation time of the measuring signal is determined by the hardware used. The delay times are in the µs range plus
the probe response time.
The measurement uncertainty is calculated as follows:
Measurement uncertainty = measuring signal propagation time x traversing velocity
Correct results can only be guaranteed for traversing velocity where not more than one triggering signal arrives per position
controller cycle.
Probe functional test
Example of functional test
The functional test for the probe is conducted favorably via an NC program.
;Testing program probe connection
N20; R11: measurement in X axis
; Preselect tool offset for probe
;Starting position and meas. velocity
; Measurement at measuring input 1 in the X axis
; Read switching signal at 1st measuring input
N80 IF R10==0 GOTOF FEHL1
;Read in measured value in workpiece coordinates
Example of repeat accuracy
This program allows the measuring scatter (repeat accuracy) of the entire measuring system (machine-probe-signal
transmission) to be calculated.
In the example, ten measurements are taken in the X axis and the measured value recorded in the workpiece coordinates.
It is possible to determine the so-called "random dimensional deviations" which are not subject to any trend.
; Start conditions, preselect tool offset for
; probe
;Prepositioning in the measured axis
; Measurement at 1st measuring input with
;rising switching edge, in the X axis
; Stop decoding for subsequent evaluation of the
; result (automatically executed when reading
; Read switching signal at 1st measuring input
N37 IF R11==0 GOTOF FEHL1
;Read measured value in workpiece ;coordinates
The measurement results R1 to R10 can be read after selecting the parameter display.
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