| 摘要 |
A device and method for enlarging a bore and installing a utility line. The device comprises an elongate shaft having a first and second end. The first end of the shaft is connectable to the drill string of a horizontal boring machine. The second end is connectable to a utility line or other device to be installed in the bore. The device is pulled through a pilot bore and enlarges the bore to a desired diameter while simultaneously pulling in a utility line. A set of cutting elements supported near the first end of the shaft, with 120 degree spacing therebetween, enlarges the bore to an intermediate diameter. A series of blades are supported on the shaft between the cutting elements and the second end. The first blade further enlarges the hole behind the cutting elements to the final desired diameter. Along its outer edge, the first blade comprises a plurality of teeth adapted to slice through the wall of the bore. Following the first blade are a second and a third blade, each of which churn the spoils created by the first blade. A central passageway through the shaft transmits drilling fluid to fluid jets positioned near the blades and the cutting elements. The fluid jets clean the blades during the reaming operation and inject fluid into the formation to mix slurry and lubricate the equipment. The device is lighter than conventional backreamers due to its unique design and configuration, yet dramatically increases the penetration and productivity rates over conventional backreamers.
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