| 摘要 |
A ram assembly for positioning in opposed cavities in a body of a blowout preventer having a vertical bore includes a first ram and a second ram. The first and second rams are movable in the cavities along a central guideway axis and between an open position to permit passage of a tubular member through the bore and a closed position to shear the tubular member. A first and a second shear member are mounted on the first and second rams, respectively. Each shear member has a pair of shearing portions disposed on opposite sides of a blade axis. Each shearing portion has a first cutting edge inclined to the blade axis at a first angle and a second cutting edge inclined to the first cutting edge at a second angle. The cutting edges are arranged to shear the tubular member, and the first and second angles are related such that the tubular member is constrained between the shearing portions as the cutting edges shear the tubular member.
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