Acco Rexel automatic binding machine

Office equipment manufacturers, Acco Rexel, required parallel development of an electronic control unit for their new Automatic Desktop Binding Machine. The mechanical development was been undertaken at their Llantrisant plant near Cardiff, Wales.

The binder was driven by an AC motor which required breaking and reversing. The unit was mains powered and had to be isolated from the rest of the unit, not only on the power supply side but also with the motor drive. Previous electrical binders had suffered from the unreliability of micro-switches for positional control – this design used optical detectors throughout which gave an improved level of reliability as well as a significant cost reduction since the units were being produced in batches of 10,000.

There were several strategies required to provide safe and stress free operation of the motor. The clippings tray, which collected the pressed out paper, needed to be monitored to lock out the motor drive when full. This was achieved at very low cost using a reflective mirror and a single transmit/receive infra-red sensor made of discrete components. The motor itself required monitoring for stall; this was achieved by observing current through the secondary windings of the motor via opto-isolation. A form of speed control was also applied to the motor control based on time-of-flight measurement.

E2L were used throughout the development of the mechanical models and undertook various changes of sensor positioning and FMEA driven solutions as the mechanical model progressed.

The project serves as a good example of close working with a client throughout the projects life, as well as liaising with their target electronics manufacturer in Hong Kong in readiness for their production batches. The unit is now manufactured in Portugal and support has continued despite the product’s migration.