Drilling head

Abstract

A drilling head includes a tubular body with top, bottom and side openings. A top closure closes the annulus between a portion of the head above the side opening and a drive tube such as a kelly extending through the head. The top closure includes a rotor, adapted to form a non-rotating seal with the kelly, and a stator, with a rotating seal between the stator and rotor. The stator is supported on and releasably connected to the body. The rotor includes a seal tube rotatably supported by inboard bearings on the stator located above the rotating seal. The seal tube has a replaceable rubber stripper to seal with the kelly. An upwardly flaring medial flange on the stripper guides upwardly flowing annulus fluid toward the side opening and away from the rotating seal. The rotor includes an elastomer sandwich drive bushing, rising above the stator into the rotary table, splined to the seal tube and secured to the kelly by slips. A segmented clamp securing the top closure to the body includes more than two segments, for fast actuation, and the segments are guided so that but one motor is required to operate all segments. The segmented clamp securing the top closure stator to the drilling head body is tightened and released by a remote controlled, rotary hydraulic motor driven screw, which is also manually actuatable. The stator has a tapered pin fitting into a conical bowl in the body with spaced upper and lower seals therebetween. The rotating seal is supplied with lubricant from outside the body via passages through the bushing and stator and body, communicating across the pin and bowl between the two seals.