| 摘要 |
A metal cup with an apertured bottom provides a junk basket. The cup is spindled on the pin of a drill bit, e.g. a tungsten carbide insert roller cone bit, the bottom edge being releasably clamped between the pin shoulder and the shoulder formed by the mouth of the box on the member forming the lower end of the drill stem, e.g. a roller reamer. The connection between the pin and box and cup form a rotary shouldered connection, the pin shoulder and/or box mouth being cut back providing a longer pin neck or shallower box to accommodate the cup. Every time the bit is removed from the stem, the interiorly upwardly flaring cup is automatically dumped. In a modification, especially for small diameter holes, in order to provide space for junk to move both up outside the cup and down into the cup, the box on the adjacent drill stem member can be fluted, e.g. with arcuate vertical section milled slots extending from above to below the rim of the cup to provide entrance for junk, so maximum exterior annulus space is left for upflow of junk; alternatively the cup aperture can be eccentric, so the space around the outside of the cup is large at one sector and the space around the box inside the cup is large at the opposite sector.
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