Patent GB-1223329-A (GB)
Title: Combined power tong and back-up tong assembly
IPC: E21B19/16
Filed: 1968-12-16
Abstract: 1,223,329. Pipe jointing &c. apparatus; chain tensioning devices. BYRON JACKSON Inc. 16 Dec., 1968 [26 Dec., 1967], No. 59730/68. Headings F2E, F2G and F2Q. Apparatus adapted to make up and break out screwed pipe joints comprises a power tong assembly T including rotatable pipe gripping jaws operable upon rotation in either direction to releasably grip and rotate a pipe P1 relative to the other pipe P2, and a backup tong assembly including a non-rotatable pipe gripping jaws operable to grip and hold the pipe P2 against rotation relative to the pipe P1 in either direction. There are means for driving the rotatable pipe gripping jaws of the assembly T including change speed transmission selectively operable for driving the rotatable pipe gripping jaws in either direction at high speed and low torque and at low speed and high torque, and a control for effecting engagement of the non-rotatable pipe gripping jaws with the pipe P2 in response to operation of the rotatable pipe gripping jaws at low speed and high torque. As shown, the assembly T, Fig. 2, is supported in an operative position above a well bore by a crane C through a cable 5 connected to a pressure-operated cylinder mechanism 7 within a post 4 so that the assembly may be raised or lowered, a cable 9, connected to the cylinder extending over a sheave 10, being connected to a slide 8 to support the mass of the tong assembly. An hydraulic motor 13 drives the transmission mechanism of the assembly. The Power Tong Assembly T includes inner and outer ring assemblies 20, 21, Fig. 6, the gear 29 of the ring 21 being driven by a gear 28 and the ring 20 being provided with the pipe gripping jaws operable in response to rotation of the ring 21 and comprising a number of circumferentially spaced jaws 30 pivotally supported on pins 31 and provided with dovetailed slots 33 to receive carriers 34 in which are removably disposed pipe gripping dies 35 to suit the size of pipe being installed. For effecting inward and outward movement of the jaws, shafts 36 each incorporate an eccentric 37 located in an elongated slot, provided with a wear pad 39, in the respective jaw, the pivoting or rotary movement of the shafts being effected by gears 38 splined thereon and meshing with and rotated by the internal gear 21a of the ring 21. To prevent rotation of the ring 20 so that the latter will not initially rotate with the ring 21 a band brake 40, Fig. 6, which engages the outer wall 22 of the ring is anchored at 41 to the tong assembly case section 15 and actuated by an hydraulic piston-cylinder actuator 45, 44 carried by a supporting body 43 which mounts a rotatable brake adjuster screw 46 engaged in a tube 46a within the bore of the piston 45; the piston extension 48 is connected to the brake anchor 49 and the tube 46a is in engagement with a stack of Bellville washers which constitute a spring sufficient normally to maintain a braking force in the ring 21. Additional braking force is established by admitting pressure fluid to the cylinder 44. There are provided stop means Fig. 7 (not shown) which function to limit relative rotation of the inner and outer rings 20, 21 in one direction or the other, depending on whether joints are being made up or broken out, to a position in which the jaws 30 are fully open; such means includes a spring-biased body 53, Fig. 6, formed with a projection which cooperates with either side of a stop anvil on the ring 21, the body being moved inwardly to allow the anvil to pass the projection when necessary by a roller 68 supported on the piston 67 of an actuator cylinder 66 and engageable with the projection 54 of the body. Inward pivotal movement of the jaws is limited by stops 32a thereon engageable with projections 32b. Guides 71b are interchangeable to adapt the tong assembly for different sizes of pipe. The case sections 14, 15 of the tong assembly T are connected to an intermediate drive section which includes the gear 28 in mesh with the outer ring gear 21 and with a gear 83, Fig. 10, on a shaft 84 and formed as a unit with a multiple sprocket 86 driven by an endless multiple chain 87. The latter extends around a sprocket 88 and the unloaded run thereof is kept taut by an adjustable and automatically shiftable slack adjuster mechanism consisting of a pair of pivoted levers 89, 90 carrying at the free ends thereof idler sprockets 91, 92 engageable with the chains 87. The levers are loaded towards one another by a tie rod 100 rotatably engaged in a block 101 and screw-threadedly engaged in a block 102. For driving the sprocket 88 a gear, Fig. 3b (not shown), on the shaft of the motor 13 meshes with an idler gear which in turn meshes with an input gear 112, Fig. 9, of the change speed mechanism, integral with drive gears 116, 117 in mesh with high speed and low speed gears 118, 119 respectively. The sprocket 88 is splined to shaft 120 extending through the hub 113 of the gears 112, 116 and 117. Drive shafts 125, 126 in parallel relation to the shaft 120 carry the gears 118, 119 and a clutch 129 is provided for establishing a drive connection between the shafts 120, 125 when the tong head T is to be driven a high speed and low torque such as when a pipe P1 is being spun initially to make up a pipe joint or to spin a joint out. The clutch 129 may be of any desired fluid-pressure actuated type and, as shown, comprises a drive member 132 keyed to shaft 125 and a driven member 133 secured to the hub section of a gear 130 normally freely journalled about the shaft 125 and in mesh with a gear 131 drivingly connected with the shaft 120. Between the plate 135 of the member 132 and an actuator piston 136 is a stack of co-engageable friction plates. Springs 37 bias the piston away from the plate 135 so that the clutch is normally disengaged, and fluid under pressure is admitted to the piston chamber 138 via a central passage 139 in the shaft 125 and radial ports 140. The low speed drive is provided with a fluid-pressure operated clutch 145 similar to the clutch 129 and which establishes a driving connection between the low-speed gear 119 and a gear 146 journalled about the low-speed shaft 126 and engaged with gear 147 connected to shaft 120. An adjustable, spring-loaded slip clutch 161 disconnects the high-speed, low torque drive from the shaft 120 when abrupt resistance is encountered as by the sudden shouldering of the tool joints 1 and 2, Fig. 2. The power fluid is supplied to the motor 13 and the clutches 129, 145 from a remote location by an operator who may select the drive to the tong head T in either direction by either effecting engagement of the high speed drive clutch 129 or the low speed drive clutch 145. The tong head may be rotated at high speed until the tool joint 1 shoulders with the tool joint 2, when the high speed clutch 129 is disengaged and the low speed clutch 145 engaged so as to impose a high torque low speed further rotation on the tool joints 1, 2 and to make the joint up tight; alternatively, in breaking a joint the tong mechanism is rotated through the low speed high torque drive prior to engagement of the high speed low torque drive. The back up tong assembly 13, Fig. 11, includes a structure 201 supported by a post 204, Fig. 2, depending from the power tong T and extending through a chamber 205 so as to be engaged by a pressure foot of a pressure sensing hydraulic device 207 which indicates the angular force applied to the back up tong. The head 209 of the assembly includes a stationary ring 217 which supports a relatively rotatable ring assembly 220 comprising an upper and lower plate provided with arcuate flanges 226 defining radially opening windows 228 through which a plurality of pipe gripping jaws 230 can be shifted between retracted and inwardly projected positions to engage a pipe part 2, each jaw consisting a U-shaped body adapted to receive an interchangeable die carrier 238 in turn adapted to receive a pipe die 240. To effect retraction and radial projection of the jaws 230 a cam ridge 251, Fig. 13, is engaged on opposite sides thereof by rollers 252, 253, the cam ridge being continuous and having three similar segments each including a central depression 251a and a pair of arcuate cam walls 251b, 251c; angular movement of the ring assembly 220 results in the jaws 230 being projected inwardly by the action of the rollers 252 on the cam walls and reversal of the direction of angular movement of the ring assembly effects retraction of the jaws by action of the rollers 253 on the ridge segments 251e. An actuator 265 effects angular movement of the jaw carrying ring assembly 220 and includes a pivoted fluid pressure actuated cylinder 266 from which projects a piston-rod 269 connected to the ring assembly 220 at one location at one side of a centre line extending from the pivot pin 267 through the centre of the tong head in order to force the ring assembly in one angular jaw closing direction and, alternatively, to be connected to the ring assembly at the other side of the centre line to cause angular movement in the jaw closing direction. The rod 269 is connected to a block 270 having a head formed with extensions disposed in the arcuate slots 279 of plates 272, the head being shifted between the limits of the slot ends 281, 282 by a fluid-pressure operated actuator cylinder 283 and locked in these positions by a retractable latching pin. An electro-pneumatic control system for controlling the application of hydraulic fluid pressure to the motor 13 clutch assemblies 129, 145, and cylinder 283 &c. is described.