MK Products MiniMicro Orbital Weldhead - Manual (Page 14)

Mini Micro ® Owner’s Manual - Page 8 ® ®
ACL
A report is generated showing the ‘measured’ time for each revolution of the
weldhead. The two readings are averaged together to give the ‘actual’ time
in seconds. This value divided into 60 seconds provides the ‘actual’ rpm.
From these results a ‘Gain error’ and a ‘Zero error’ is calculated. These
are printed as percentages on the report, and are used by the computer
to convert the speed demanded by the procedure into a speed, which will
result in the proper actual value by the motor control.
The report also shows the data for the tachometer, and computes a
corresponding Gain and Zero error value. The computer corrects the motor
speed values shown by the display bar graph to represent true values.
The far right column of the report shows an ‘Update’ value for the motor
and tachometer. This update column is only present when using a weld
procedure with the “Pre Weld Home” option. Prior to beginning a weld, a
procedure with this option will cause the rotor to complete one revolution
at the high speed used in the initial calibration. The computer times this
revolution and a gain correction is derived. The purpose of this procedure is
to calibrate the weldhead before each weld where environmental changes
may affect the weldhead speed.
Motor Calibration Data
08/07/01 15:45:04 / 08/07/01 15:45:04“Gain Error = 3.5% / Zero
error = 0.05 RPM
Cal Actual Cal Actual Measured Update
RPM RPM Sec Sec Sec Sec Sec
6.00 5.84 10.00 10.27 10.27 10.26 0.00
2.00 1.98 30.00 30.36 30.60 30.05
Tachometer: Gain error = -4.1% / Zero error = 0.13 RPM
Actual Read Measured Update
RPM RPM RPM RPM Sec
5.84 5.96 5.96 5.96 0.00
1.98 1.93 1.91 1.94
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 .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.
Section
B Cont.