| 摘要 |
<p>There is disclosed an improved drilling head which provides for the formation of a continuous seal about a drilling string, where the drilling string consists of varying diameter drill string components. A stationary bowl (3) configured to pass a drill string is provided with an annular groove (24) about the top so as to allow for the attachment of a connecting clamp (30). An assembly carrier (50) is provided which is removably disposable within the bowl and to which a lower stripper rubber (38) may be attached. A bearing assembly (80) adapted for placement within the assembly carrier is provided with an upper rotatable stripper rubber (70) of smaller diameter that the lower stripper rubber so as to form a seal on smaller diameter drilling strings.</p> |
