Patent GB-399468-A (GB)
Title: Well drilling equipment for handling drill pipe and casing in high pressure wells
IPC: E21B3/04
Filed: 1932-01-01
Abstract: 399,468. Well-drilling. NATIONAL SUPPLY CORPORATION, 120, Broadway, New York, U.S.A. Jan. 1, 1932, No. 101. Convention date, Oct. 19, 1931. [Class 85.] A rotary machine for well-drilling comprises a rotary table and slips mounted therein, and means whereby the slips can be actuated automatically or manually for holding the drill stem from vertical movement in either direction relative to the rotary table. A rotary-drilling machine 3 preferably comprising a rotary table 14 with hydraulic lifting and lowering means, as described in Specification 377,344 is arranged above a well casing 8 provided with a stuffing box 7 and with a control valve 5 and blow-out preventers 6 preferably controlled through chains 9 ; below the valve 5 is a conduit 11, with valve 13, for return of the flushing fluid. The drill pipe 12, preferably flush-jointed, is driven from the rotary table 14 through a split drive bushing 15 held in the table by locking bars as described in Specification 357,912, and containing upper and lower sets of oppositely tapered serrated slips 39, 40, either set of slips being engaged with the drill stem according to the tendency of the latter to fall or to be expelled by the pressure in the well. The bushing 15 has a polygonal upper end engaging a corresponding recess in the table 14 for driving purposes, and a split guide ring 38 with locking flange 38a is connected to the lower end of the bushing to guide the drill stem ; each half of the bushing has eyes 15a entering recesses in the other half and bolts 15c, passing through the eyes and provided with a flattened side, may be rotated to engage flattened projections 15g to lock the halves together. The upper set of slips 39 is connected to the lower set 40 by links 50 and to an operating head 47 by links 49, the links 49, 50 being so arranged that the slips tend to swing away from the drill stem. The head 47 is raised or lowered manually by means of a lever 53, pivoted at 54 to a bracket 55 on the rotary table guard 56, whereby either set of slips may be engaged. For automatic control of the slips, a flanged sleeve 60, Figs. 3 and 4, projects into the head 47 and has openings 61, 62 through which oppositely-acting, spring- pressed sets of dogs 63. 64, carried by the head 47, project into engagement with the drill stem whereby vertical movement of the drill stem in either direction causes movement of the head 47 in the same direction and consequent engage ment of the corresponding set of slips. A safety lever 73, pivoted at 74 to the lever 53, is held with the latter during manual control whereby rollers 75 on the lever 73 are held in engagement with a track 77 on the flanged sleeve which then, through pins 67, 68, holds the dogs 63, 64 in inoperative position ; on releasing the levers, a spring 78 moves them apart and frees the automatic control of the slips for action. During ordinary drilling operations, the lower slips 40 may be forced into gripping position by screws inserted in openings 79 of the bushing, whereby slip of the drill stem is prevented. The Specification as open to inspection under Sect. 91 of the Acts describes also means for forcing the drill stem into the well against pressure, or for controlling the withdrawal thereof, comprising a spider 16, Fig. 7 (Cancelled), connected by clevises 22 and a cable to a counterweight, and by clevises 22a to further cables which pass downwards from the spider and around pulleys and are then connected to a cable passing to a winch with band brakes. The spider includes arms 21 embracing a central internally tapered body 80 with upper and lower pipe guides 82, 81 ; tapered slips 85, connected by dowels and pressed apart by springs, are operated by a lever 88 to engage the drill stem and have depending lugs 90 engaging the lever to prevent rotation of the slips. This subject-matter does not appear in the Specification as accepted.