Computer Modeling for Roadheaders
Performance prediction for road header machines is more difficult compared to full-face machines (e.g. TBM). This is partly because operator's skill affects the production rate significantly. Roadheaders also are less rigid because the cutterhead is mounted on a boom that must transfer energy from the machine.
Face excavation consists of several modes of cutting: sumping (into the face), arcing (across the face) and shearing (down the face). In each mode, only part of the cutterhead contacts the rock. Even among cutters in contact with the face, the depth of penetration varies, depending on the spatial and temporal position of each cutter. The production rate can vary between two operators depending on their choices of cutterhead movements, sequencing and use of available power.
The immense variability of roadheader machine operation means that exact performance predictions cannot be expected from semi-theoretical methods that use cutting forces. However, the maximum production rate achievable in each cutting mode does indicate the limits of the machine and provides an upper bound on the expected production rates.
The effects of rock joints, fractures, inflows, etc. on the performance of these machines also are not modeled easily. Empirical models developed for performance prediction of partial face machines generally have had more success than semi-theoretical models.
Some of them are: