Self adjusting dull and broken tool monitor
The COMPENSATOR Motor Load Control (Model
PCR1810), manufactured by Load Controls Inc, is a very effective
unit for machine tool monitoring. This highly sensitive
system allows sensing of the machine spindle power and
set points are used to indicate dull tools and broken tools. By
sensing power, rather than amps, it is sensitive enough to work
with a wide range of tool sizes including small tools.
The control also has a compensating feature
which will zero out the baseline power. The machine baseline
power changes significantly as temperatures change, coolant and
the lubricant viscosity change and the mechanical clearances
change.
During each machine cycle when the process is
in its baseline or idling position a contact closure is sent to
the control from a limit switch (or from a programmable
controller) and the control learns this value and retains it in
memory during the next machine cycle.
The control then looks for an increase above
this baseline value. By zeroing out the inherent machine drift ,
the control is quite precise. A special filtering scheme is used
to insure fast response, it is easy to install since it requires
no machine modifications and is a low cost solution.
For monitoring a single tool on a single
spindle, the COMPENSATOR motor load controls detects dull tools and broken tools
and performs just as well as the more
sophisticated systems, which are much more expensive.
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