Underground » Roadway Development
The aim of this project was to develop an enclosure and mounting bracket to suit a future machine-mounted floor horizon sensing system for roadway development.
The goals of this project were to:
- design and develop an enclosure that can house a GPR sensor; and
- design, develop and trial a bracket to mount the enclosure to a miner bolter.
A non-metallic enclosure was developed based upon an enclosure design certified to AS60079 ex p static pressurisation. The dimensions of this enclosure were selected based on current GPR technology and payload to function in this roadway development floor horizon sensing task. The Sandvik MB650 was the selected candidate miner bolter for this project. Several locations to mount the enclosure on an MB650 were identified.
A bracket was designed to mount the enclosure to the apron, utilising a U-spring to push the enclosure and ensure the enclosure base maintained contact with ground surface when the apron moved in the forward direction (either tram or sump-in processes).
The bracket and enclosure were developed, installed and trialled on an MB650 miner bolter. Both functioned correctly during tramming and sump-in/out processes. However, there was concern during these tramming evaluations that the U-spring was at risk of yielding due to over-compression when operating unsupervised during production. The impacts of the U-spring yielding are the sensor enclosure would no longer maintain contact with the ground which degrades performance of the sensor, or the enclosure could detach from the bracket resulting in the enclosure and payload becoming destroyed by the miner or apron.
The U-spring eventually failed when the miner apron and cutter head were lowered whilst the canopy foot was in the raised position to adjust the tension of the miner tracks. The edge of the enclosure became caught by the canopy foot which caused the U-spring to fold in on itself and fail at the connection with the enclosure. The rear side of the skid base cracked and the heads of the bolts that were hit by the canopy foot were damaged. However, the enclosure remained undamaged. If the U-spring didn't fail, it is still unlikely this method would have been the final mounting method chosen for this application due to the concern of U-spring yielding. Alternative mounting approaches and locations have been identified and are proposed in the report.