Rotary drilling head

Abstract

In accordance with the present invention, the drilling head includes a body or spool having a flow bore and a removable side outlet. Upon removal of the side outlet, the drilling head will pass through most rotary tables. The drilling head further includes a closure member for closing the annulus between that portion of the drilling head above the side outlet and a drive tube, such as a kelly, extending through the drilling head flow bore. The closure member includes a nonrotating support tube and a rotating seal tube adapted to form a nonrotating seal with the drive tube. The seal tube is rotatably supported by bearings within the support tube. The closure member is small enough to pass through even rotary tables that are too small to pass the drilling head. A segmented clamp secures the closure member to the drilling head body around one end of the flow bore. The clamp includes at least two segments, for fast actuation, having one end connected to a variable length linkage. The variable length linkage includes a nut pivotally connected to one segment, a screw engaging the nut, and a pivotal connection connecting the screw to another segment. The segmented clamp is tightened and released by a remote controlled, variable torque impact motor. The motor is housed within a support bracket mounted on the segmented clamp and is connected to the screw of the variable length linkage by a drive connection. Springs bias the motor against the screw. The motor fits loosely within the support bracket and is permitted limited movement in all directions. The impacting variable torque motor applies a series of rotational hammer blows to the screw to break the connection and then a smooth normal torque to continue the disengagement of the clamp.