Renishaw RMP60, Руководство по установке

Страница: 33 / 68

3.9
System installation
Calibrating the
RMP60
Why calibrate a probe?
A spindle probe is just one component of the measurement system which communicates with the
machine tool. Each part of the system can introduce a constant difference between the position that
the stylus touches and the position that is reported to the machine. If the probe is not calibrated,
this difference will appear as an inaccuracy in the measurement. Calibration of the probe allows the
probing software to compensate for this difference.
During normal use, the difference between the touch position and the reported position does not
change, but it is important that the probe is calibrated in the following circumstances:
•
When a probe system is to be used for the first time.
•
When the trigger filter is changed.
•
When a new stylus is fitted to the probe.
•
When it is suspected that the stylus has become distorted or that the probe has been crashed.
•
At regular intervals to compensate for mechanical changes of your machine tool.
•
If repeatability of relocation of the probe shank is poor. In this case, the probe may need to be
recalibrated each time it is selected.
It is good practice to set the tip of the stylus on-centre, because this reduces the effect of any
variation in spindle and tool orientation (see page 3.7,
“Stylus on-centre adjustment”
, for further
information). A small amount of run-out is acceptable, and can be compensated for as part of the
normal calibration process.
Three different operations are to be used when calibrating a probe. They are:
•
Calibrating either in a bored hole or on a turned diameter of known position.
•
Calibrating either in a ring gauge or on a datum sphere.
•
Calibrating the probe length.
Calibrating in a bored hole or on a turned diameter
Calibrating a probe, either in a bored hole or on a turned diameter of known size, automatically stores
values for the offset of the stylus ball to the spindle centre line. The stored values are then used
automatically in the measuring cycles. Measured values are compensated by these values so that they
are relative to the true spindle centre line.