| 摘要 |
Cutting heads, cutting head systems, and methods for creating an excavation in a mineral seam. A preferred cutting head includes a first body having a manifold for containing high pressure fluid and an axis of rotation generally parallel to the borehole, a first plurality of mechanical bits disposed on the first body, a first plurality of nozzles disposed around the axis of rotation for spraying the high pressure fluid, and a plurality of tubes fluidly coupling the manifold and the first plurality of nozzles. On supplying high pressure fluid to the manifold and rotating the cutting head about the axis of rotation, the nozzles create a generally circular, overlapping pattern of high pressure fluid in front of the cutting head, the pattern of high pressure fluid being directed to cut the borehole independently of the mechanical bits.
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