| 摘要 |
A drill bit for cutting a formation that tends to form ridges comprises: a bit body having a bit axis, a plurality of rolling cone cutters rotatably mounted on the bit body, with each rolling cone cutter having a generally conical surface, a plural ity of primary cutter elements extending from one of the cone cutters in a first row, e ach primary cutter element having an outer side and an inner side, and a plurality of ridgecutting cutter elements extending from the same cone cutter, the first plurality of ridge-cutti ng cutter elements being positioned adjacent to the outer side of the first row of primary cutter elements. Each ridge-cutting cutter can be, but is not necessarily, on the same cone cutter as the primary cutter element adjacent to which it cuts, and is preferably posit ioned on a land or flat adjacent to that primary cutter element. Each primary cutter elemen t in one or more rows can be provided with a ridge-cutting cutter element and the ridge-cutt ing cutter element can be angled with respect to the axis of the primary cutter element.
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