Current Sensors

One method that has been increasingly used in recent years for indirect force measurement is recording the effective power of the main spindle.

It is defined as:

P = V3U • I • cos p (10.1)

The effective power of the main spindle is in direct relation with the torque de­livered at the shaft of the motor. Every event at the shaft is thus mirrored by the power input of the drive. Since the electrical voltage is preset at the motor, the re­quired power can be captured by the current input. The current is measured by

Hall sensors. The mounting of these sensors is achieved simply in the switchboard of the grinding machine, such that an unproblematic retrofitting of the machines is possible. The disadvantage for service life monitoring is that only the tangential force can be computed with the help of the effective power. Yet since grinding wheel wear is, as is generally known, best correlated with the cutting force factor p, defined as the quotient of tangential to normal force (Ft/Fn), judging the end of the machine’s service life with the effective power is only possible in some cases. An essential advantage of effective power sensors as opposed to force sensors is that they function free of drift.

Updated: 24.03.2016 — 12:06