| 摘要 |
A screw-type, in-ground anchor device for anchoring an above-ground upright. A generally cylindrical drive shaft includes an upper cylindrical housing portion constructed of ¼-inch rolled steel with an inside diameter sized to match the outside diameter of the upright. A conical portion connects the upper housing portion to a lower tip portion. The surface of the conical portion has a slope of less than 20 degrees, and preferably in the range of 5-10 degrees. A set of screw threads (flightings) are attached to the tip portion and have a diameter that is approximately equal to or less than the diameter of the upper housing portion. The flightings operate in soil to screw the anchor device into the ground when the device is rotated. The conical portion outwardly compresses the soil that is disrupted in the wake of the flightings. Since the flightings have a diameter approximately equal to or less than the diameter of the upper housing portion, soil surrounding the drive shaft is not disrupted. Therefore, the outward compression of the soil creates a tightly compressed soil shaft having the same diameter as the housing portion.
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