MK Products Copperhead Weldhead - Manual (Page 17)

CopperHead ® Owner’s Manual - Page 9
What does all this mean to the operator? It means that the ACL ® will cali-
brate the weldhead to its own motor voltage output and compensate for
calculated errors derived during the Motor Calibration Sequence.
The Motor Gain Error percentage is exactly how much the ACL ® will compen-
sate for with a particular weldhead connected.
When a new or repaired weldhead is received, a calibration should be run to
“benchmark” its performance. This initial “benchmark” calibration check can
then be used to compare prior calibration reports to determine the condition
of the weldhead. If the ‘Gain error’ is more than 10% and ‘Zero error’ more
than 0.5 rpm off of the benchmark calibration then the weldhead should be
disassembled and cleaned.
If the ‘Gain error’ reaches 50% or the ‘Zero error’ reaches 2 rpm during
a calibration check, the computer will state “DO NOT WELD”. At this
point, however, the weldhead may have sustained considerable damage.
Therefore, it is important to monitor the ‘Gain error’ and ‘Zero error’ and
provide maintenance as necessary. Reference the Sample ACL
® Calibration
Error Printout in Table 2.
Motor Calibration Data
08/07/01 15:45:04 / 08/07/01 15:45:04
Gain Error = -.- % / Zero error = -.-- RPM
Cal
RPM
Actual
RPM
Cal
Sec
Actual
Sec
Measured Update
Sec Sec Sec
6.00 0.00 10.00 0.00 0.00 0.00 0.00
2.00 1.98 30.00 30.36 30.60 30.05
Tachometer: Gain error = -4.1% / / = 0.13 RPM
Actual
RPM
Read
RPM
Measured Update
Sec RPM RPM
0.00 0.00 0.00 0.00 0.00
1.98 1.93 1.91 1.94
Cal Time Error: *DO NOT WELD*
Weldhead Calibration Sequence – CobraTig ®
Due to small variations among weldheads and because the CobraTig ® uses
a tachometer feedback control system, there are small but significant varia-
tions in speed among the weldheads for the same command from a particu-
lar CobraTig
® .
To account for these variations, the CobraTig ® provides procedure to mea-
sure the variation and then to factor out the variation so that the weldhead
can maintain absolute and repeatable results: a Motor Calibration sequence
performed from the Calibration Menu.
Motor Calibration Sequence
Upon initiation of the Motor Calibration sequence, if the rotor is at home posi-
tion, it backs up slightly then starts rotating in its normal welding direction for
one complete revolution from home switch closure to home switch closure
at a default low speed setting of 2 rpm. Once complete, the weldhead rotor
again backs up slightly, increases speed and continues in its normal weld-
ing direction for one complete revolution from home switch closure to home
switch closure at a default high speed setting of 6 rpm.
Sample ACL ® Calibration Error Printout
Table 2