Patent GB-1515974-A (GB)
Title: Rotary drilling rig
IPC: E21B19/084
Filed: 1976-04-20
Abstract: 1515974 Boring earth &c. GARDNERDENVER CO 20 April 1976 [14 Oct 1975] 15907/76 Heading E1F [Also in Division B3] A rotary drilling rig (Fig. 4) includes a mast 30, a head 50 disposed on the mast for linear travel, coupling means such as a sub 56 (Fig. 7) attached to a swivel unit 54 on the head 50 for connection to a drill pipe or string, a pulldown mechanism, e.g. driven by cylinders 72, connected to the head 50 to exert pulldown and hoisting movements on the head 50 and drill string, and a rotary drive unit 180 adapted to move along the mast with the head 50 to operate as a rotary top drive for the string (Fig. 7), a drive connection being formed between the drive unit 180 and the string, and the drive unit 180 also being adapted to be disposed at the lower end of the mast (Fig. 4) independent of the movement of the head 50, e.g. for rotary table drilling. As described, the mast 30 includes a pair of spaced apart linear guide tracks 48, both the head 50 and drive unit 180 having guide means engageable with the tracks to maintain alignment along the drilling axis. The tracks 48 include upper portions 49 that turn inwards so that the head 50 can be moved into a position out of alignment with the drilling axis (as in Fig. 4). The pulldown mechanism includes chains 68, 70 which are connected at one end to members 66 attached to the head 50. The respective chains 68, 70 pass over sprockets 82, 76 and 84, 78, and are connected at their opposite ends to chain tensioning devices 86, 104 fixed to the mast 30. The sprockets 76, 78 are mounted on the ends of the rods 80 of the driving cylinders 72. With the head 50 in its withdrawn (Fig. 4) position, a travelling block 108 may be used for hoisting or lowering drill string along the drilling axis, the block 108 being suspended by a cable 110 fed from a winch 118. The block 108 carries a threaded plug for engagement in the upper end of a drill pipe. The mast 30 also carries a positioning mechanism 150 (Figs. 4, 10) for moving drill pipe members 38 between the drilling axis and a retracted position, the mechanism 150 including arms 158 attached to a shaft 152 which is caused to rotate by a cylinder 156. Each arm 158 has a movable jaw member 164 actuated by a cylinder 166, conical disc springs 174 urging the jaws to the gripping position. The mast carries auxiliary hoisting means to move pipe members 38 between the positioning mechanism 150 in its retracted position and a tray where the pipes 38 are stored. These hoisting means include a cable 124 fed from a winch 126 and carrying a hook 134 to engage a sling (Fig. 15, not shown) attached to a pipe member 38. The rotary drive unit 180 comprises a tubular drive member 184 having a bore 185 through which projects the drill string or e.g. casing. For coupling to the string, the member 184 has a polygonal recess 186 in which is removably disposed an interfitting collar 188 which is fixed to the sub 56. The drive member 184 is connected by a chain 192 to a reversible hydraulic motor. In rotary top drive operation, the drive unit 180 is connected to the members 66 by pins 202, and a bushing 224 (Fig. 12) is disposed on the deck of the rig, the bushing carrying a wrench 234 which has a slot 236 for cooperation with flats formed on the outside wall of drill pipes 38. The wrench allows the string to be held nonrotatably for making and breaking threaded connections. However, when withdrawing long drill strings, it may be more convenient to place the drive unit 180 on the deck, and the bushing 224 in the recess 186 in the unit 180. Then, whilst the string can be rotated by the unit 180, the uppermost pipe member 38 can be held by a pipe breakout wrench (210) (Fig. 3, not shown) mounted adjacent the mast 30. Alternatively, for increased torque, the wrench 234 can be fixed relative to the mast, and the breakout wrench actuated to break loose the connection. For use as a rotary table drive, a kelly can be connected to the head 50, a cooperating bushing being disposed in the recess 186 in the drive member 184.