GB1464149A - Rotary driving heads for drill strings - Google Patents

Abstract

1464149 Rock drilling; making up pipe joints TRW Inc 24 Dec 1974 [26 Dec 1973] 55696/74 Headings B3C and B3N [Also in Division E1] A rotary driving head, e.g. for a rock drill, has a drive spindle 15 having a threaded end portion 42 for connection to a threaded connector 43 on a drill pipe 46, and a reciprocable splined plunger 34 mounted in the drive spindle 15 for movement between a retracted position (not shown) and an advanced position (Fig. 1) in which the plunger 34 engages spines 47 in the drill pipe connector 43, thus locking the drill pipe 46 and spindle 15 against relative rotation, e.g. when breaking pipe joints in the drill string. As described the spindle 15 is driven by a hydraulic motor 13 via planetary gear set 12, shaft 14, bushing 21 and keys 19, 20. The plunger 34 is slidable in a chamber 16 in the spindle 15, a splined collar 36 fixed to spindle 15 by pin 38 preventing relative rotation between the plunger 34 and spindle 15. The plunger 34 is biased towards its retracted position by spring 35 and is moved to its advanced position by supplying pressure fluid through lines 50 and ports 51, 53. The rotary driving head 80 (Fig. 4) is movable vertically along a mast 81, by a cable and pulley system (not shown), the apparatus also including pipe gripping means 82 (Fig. 4a) consisting of jaws 83, 84 moved together by piston and cylinder 87. The drill string is withdrawn from the borehole 91 as follows: first the pipe joint 92 between sections 88, 90 is positioned below the pipe gripper 82 (Fig. 4) which is then actuated. The motor of head 80 is then rotated (with plunger 34 retracted) in the reverse direction through half a turn to loosen the joint 89 between drive spindle 42 and pipe section 88. The head 80 is then raised until the joint 92 is above the grippers 82 which are again actuated. Plunger 34 is then extended and the motor is driven in reverse to loosen and unscrew the joint 92, torque from the motor being transmitted to the pipe section 88 via plunger 34 and splines 47. The plunger 34 is then retracted and the motor is again driven in reverse to unscrew the joint 89. The pipe section 88 can then be removed and the head 80 is then lowered and connected to the next section 90 by driving the motor forwardly. The head 80 is then raised to withdraw pipe section 90 from the borehole, this procedure being repeated until the entire string is removed from the borehole.