Portable Optical CMM for Extreme Applications 29-02-2008
The precise measurement of a sprocket gear on a dam wall 8 metres above water level demonstrated the incredible portability of the Actiris350 portable CMM in action, available from IS Tecnik.
Successfully undertaken by ATM-3D, this metrology was necessary to measure the wear on a critical chain drive sprocket working the dams flood gates, without undertaking the major logistical task of disassembling the system.
Apart from highlighting the Actiris350 system's brilliant portability, the job was also made feasible by the unique capability of the Actiris optical system to precisely monitor the position of multiple targets in real time, thus effectively measuring both the component position as well as the points probed during each measurement, to allow an instantaneous determination of their actual spatial relationship.
The job setup had the portable CMM system's twin-camera sensor eyes fixed to a long mobile boom pole, suspended down from the top of the dam.
At the same time an operator was able to absail safely down to the sprocket gear position carrying the lightweight and connection free handheld measurement probe, fitted with a standard 6mm ruby stylus.
By placing three simple magnetic reflectors on the sprocket, the component datum was able to be dynamically tracked throughout the measurement session, so that the movement of the system suspended in space and of the operator's probe did not affect the accuracy of the measurements.
According to David L'Homme, manager of ATM-3D, "measurements are carried out without loss of accuracy even if the sensor is moving in front of the part".
The acquisition of surface curves and geometric features was necessary to reconstruct the sprocket, creating an IGES format CAD file from the measurement data so that the parts worn surfaces could be compared to their nominal profile.
Surface deviations were found to range from 0.15 to 0.35mm from their nominal values.
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