| 摘要 |
An earth boring bit having a body and a cantilevered bearing shaft extending inwardly and downwardly from the body. A rotatable cutter with an open end is assembled over the shaft, which has a radial bearing surface formed around a longitudinal axis. The cutter has a radial bearing surface sized to permit assembly over the journal surface of the shaft. The shaft and cutter have opposed thrust bearing surfaces, one of which has a gradually tapered outer region and a planar inner region to gradually reduce peak stress from a maximum to a minimum and avoid abrupt changes in stress from a high to a low value.
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