Automatic measurement station of commutator of electric rotors

This customizable automatic measuring station allows the measurement of the commutator profile of electric rotors. Moreover, it processes the profile data to obtain detailed information on the geometric characteristics of the commutator. The main measurements include:

• Diameter: measurement of the minimum and maximum diameters of the commutator, excluding the areas corresponding to the cavities.
• Run-out: measurement of total axial run-out (max – min), excluding cavities areas. Run-out can be broken down into eccentricity and roundness components in order to identify the dominant cause of the geometric error (e.g., shaft deflection, incorrect clamping during turning, etc.).
• Delta-bar: measurement of local oscillation (max – min) for each individual commutator bar. The values detected, including the maximum peaks, are displayed numerically and represented graphically on a polar plot, allowing immediate and intuitive control of the profile.
• Bar-to-bar: difference in height between two adjacent commutator bars separated by the cavity. Again, the results are available in both numerical and graphical formats on a polar plot, for quick and accurate visual analysis.

Measurements are performed using a pneumatic extension LVDT sensor with a resolution of 0.1 μm, entirely managed by the station to ensure precision, repeatability, and automatic process control.

Automatic line integration

The station is designed to operate within automated lines, both with pick-and-place systems and anthropomorphic robots. Communication with the line’s PLC is fully customizable and compatible with the main models on the market. The rotor can be positioned on the station with an axial tolerance of a few millimeters, as the precision positioning required for measurement is performed autonomously by the station.

The typical cycle time for a measurement is 4.0 seconds, with the possibility to further reducing it for demanding applications.

The station control software receives from the line’s PLC the serial number of the rotor under measurement, thus ensuring complete traceability of the acquired data. In addition, the station returns the measurement outcome to the line’s PLC even before the part is completely released, allowing timely management of the next processing step, with automatic classification of the rotors as compliant or rejected.

Rotor positioning and rotation

The rotor is placed on V-shaped supports in the specific reference positions of the shaft indicated in the drawing, in order to faithfully reproduce the actual working conditions. Two cylinders, oriented along the rotor axis – one with a fixed stop and the other mounted on a spring-loaded carriage – ensure the correct positioning of the piece before measurement. Subsequently, a belt carriage is lifted to rotate the rotor.

This solution uses an innovative and unique rotation technique. Unlike traditional systems, where the collector is pushed vertically downwards onto the lamellar pack, this technology allows to:

• perform measurements with minimal mechanical stress, thanks to the partial compensation of the weight force obtained through the vertical push of the belt, thus reducing any possible rotor deflection;
• optimize the cycle time, as the rotor remains accessible from above at all times: no mechanical obstructions interfere with the measurement area, ensuring greater efficiency and ease of handling.

Sitec Mensura, the customizable metrology software

The measuring station is equipped with Sitec Mensura, a customizable multilingual software, that coordinates the station’s operation in an integrated manner and processes the acquired data to determine the commutator geometric characteristics. The software is installed on an industrial PC supplied with the station, ensuring reliability and operational continuity even in demanding production environments.

The intuitive and user-friendly UI allows you to monitor the system status in real time and view the report of the latest measurement, including both the numerical values and the corresponding polar plot, providing a clear and immediate representation of the commutator profile.

The measurement reports can be exported in customizable formats (.csv, .xlsx, etc.) and include:

• the raw measurement profile,
• the processed measurements (diameter, oscillation, etc.),
• the inspection result (compliant/non-compliant),
• the polar diagram image.

This data allows for complete traceability of measurements for each individual rotor, facilitates in-depth post-analysis, and enables the implementation of statistical process control (SPC).

Through the settings page, the user can customize every aspect of the measuring station, from diagnostics to the configuration of processing algorithms, from acceptability limits to export modes, thus adapting the system to specific production and quality requirements.

Predictive maintenance of the measuring probe

One of the main features of this product is its predictive maintenance capability, designed to ensure smooth production and prevent unexpected downtime. By constantly monitoring the measurement profile, the software can detect the first signs of wear on the probe tip and predict when maintenance will be required, before a failure occurs.

This means:

• Fewer unexpected shutdowns
• Longer equipment life
• Data-driven maintenance planning