A unique piece of experimental research equipment has been developed at Cambridge University to understand, probe and monitor the fundamentals of granular flow. The system provides a continuous steady flow of quartz grit down a 4m long modular open channel or chute, which can be varied in length and be inclined through a range of slip angles from 30-60 degrees. In order for data to be gathered successfully, a carriageway measuring 500 x 400mm is mounted to the chute directly above the flowing product. This carriageway is driven linearly by a geared motor and is required to traverse the whole length of the inclined chute whilst an experimental run is in operation. The carriageway must be stable whilst it moves linearly and any rail system used must be trouble free and give accurate repeatable incremental movement. The criteria for any mechanism used for supporting the carriageway was that it must be able to run successfully in a harsh abrasive environment, must be stable and provide a rigid platform for the measuring equipment. Any bearings or slideway used must be able to run in a dry state with no wet lubricant exposed that could attract dust. Finally, the drive mechanism used must be able to support the weight of the carriageway and measuring equipment when the chute is inclined and provide a positive and robust drive action when the carriageway is moved incrementally. A linear actuator from the igus® range was chosen. The drylin® ZLW toothed belt drive came complete with two carriages, one attached to the drive belt and the other free, with both carriages fixed to the 500mm long the instrumentation carriage. The linear actuator used iglidur® polymer plain bearings. In order to support the weight and other side of the instrumentation carriageway, an aluminium square rail was chosen, complete with floating bearings that enabled us to easily align the carriageway between the two rails. These were self-aligning yet provided a rigid location for the carriageway. manus 06 ® Large re-circulating system for research into granular flow Both the linear actuator rail and the square rail have been mounted on aluminium machine build profiles. "By using this system as a solid base, it enables us to easily reposition the complete carriageway and slide when the length of the chute needs to be changed."
University of Cambridge