automated power tong american patent made in china

This invention relates to the field of devices for rotating tubular members so as to make up or break out threaded joints between tubulars including casing, drill pipe, drill collars and tubing (herein referred to collectively as pipe or tubulars), and in particular to a power tong for the improved handling and efficient automation of such activity.

In applicant"s experience, on conventional rotary rigs, helpers, otherwise known as roughnecks, handle the lower end of the pipe when they are tripping it in or out of the hole. As used herein, the terms pipe and tubular are used interchangeably. The roughnecks also use large wrenches commonly referred to as tongs to screw or unscrew, that is make up or break out pipe. Applicant is aware that there are some other tongs that are so called power tongs, torque wrenches, or iron roughnecks which replace the conventional tongs. The use of prior art conventional tongs is illustrated in FIG. 1a. Other tongs are described in the following prior art descriptions.

In the prior art applicant is aware of U.S. Pat. No. 6,082,225 which issued Feb. 17, 1997 to Richardson for a Power Tong Wrench. Richardson describes a power tong wrench having an open slot to accommodate a range of pipe diameters capable of making and breaking pipe threads and spinning in or out the threads and in which hydraulic power is supplied with a pump disposed within a rotary assembly. The pump is powered through a non-mechanical coupling, taught to be a motor disposed outside the rotary assembly.

In the present invention the rotary hydraulic and electrical systems are powered at all times and in all rotary positions via a serpentine such as a serpentine belt drive, unlike in the Richardson patent in which they are powered only in the home position. In the present invention the pipe can thus be gripped and ungripped repeatedly in any rotary position with no dependence on stored energy and the tong according to the present invention may be more compact because of reduced hydraulic accumulator requirements for energy storage wherein hydraulic accumulators are used for energy storage only to enhance gripping speed.

Applicant is also aware of U.S. Pat. No. 5,167,173 which issued Dec. 1, 1992 to Pietras for a Tong. Pietras describes that tongs are used in the drilling industry for gripping and rotating pipes, Pietras stating that generally pipes are gripped between one or more passive jaws and one or more active jaws which are urged against the pipe. He states that normally the radial position of the jaws is fixed and consequently these jaws and/or their jaw holders must be changed to accommodate pipes of different diameters.

Applicant is further aware of United States Published patent application entitled Power Tong, which was published Apr. 5, 2007 under Publication No. US 2007/0074606 for the application of Halse. Halse discloses a power tong which includes a drive ring and at least one clamping device with the clamping devices arranged to grip a pipe string. A driving mechanism is provided for rotation of the clamping device about the longitudinal axis of the pipe string. The clamping device communicates with a fluid supply via a swivel ring that encircles the drive ring of the driving mechanism. Thus Halse provides for three hundred sixty degree continuous rotation combining a spinner with a torque tong. The Halse power tong does not include a radial opening, the tong having a swivel coupling surrounding the tong for transferring pressurized fluid from an external source to the tong when the tong rotates about the axis of the pipe. Halse states that having a radial opening in a power tong complicates the design of the power tong and weakens the structure surrounding the pipe considerably, stating that as a result, the structure must be up-rated in order to accommodate the relatively large forces being transferred between the power tong and the pipe string. Halse further opines that a relatively complicated mechanical device is required to close the radial opening when the power tong is in use, and in many cases also to transfer forces between the sides of the opening. The Halse tong is not desirable for drilling operations because there is no throat opening to allow the tong to be positioned around the pipe at the operator"s discretion. The pipe must always pass through the tong.

The power tong according to the present invention continuously rotates tubulars for spinning and torquing threaded connections. Continuous rotation is achieved through a rotating jaw (also referred to as a rotor) that has grippers that grip the tubular. Hydraulic and electrical power necessary for actuating the grippers is generated on board the rotor since the continuous rotation does not allow for either hydraulic or electrical external connections. A serpentine member such as a serpentine drive belt system turns the motors of an on-board hydraulic power unit and electric generators which may be AC or DC generators, to supply the grippers with the necessary hydraulic and electrical power.

The present invention includes a rotor rotably mounted in or on a rigid structural framework or stator frame. A main drive drives the rotor. The rotor may be supported and held in position by the use of opposed helical pinions/gears which support the rotor vertically and guide bushings which locate it laterally and support it vertically when the torque is low. The grippers, which may be actuated by hydraulic gripper cylinders, maybe held in position by links and guide bushings that can withstand the torque parameters of the tong. The gripper cylinders may be moved in a range of travel by an eccentric. This provides for a tong that can accommodate a large range of pipe diameters (3.5 inch drillpipe to 9-⅝ inch casing or larger). A centralizing linkage ensures that the pipe is gripped concentricly with the tong axis of rotation. The tong does not require a mechanical device to close the radial opening. The on-board power source and rotary control system allow the present invention to have fully independently activated and controlled rotary gripping of the tubular. It is capable of high torque for making and breaking and high speed for spinning, all within one mechanism. One embodiment of the present invention also overcomes the limitation of the spinning wrench engaging the stem area of the drillpipe which over time will cause fatigue in the stem area as the spinning and torquing according to the present invention is accomplished with the same jaw that engages the pipe on the tool joint. The throat of the jaws according to the present invention has an opening of sufficient diameter to accept a tubular. The throat cooperates with the opening to allow the power tong to be selectively positioned around the pipe at the operators" discretion.

FIGS. 18 and 19 are in diagrammatic plan view, a further exemplary embodiment of the nested transmission of the tong, showing the use, by way of example, of two stator sprockets, at least one of which is driven, having a serpentine member therearound and reaved over a pair of rotor sprockets on the throated rotor, the pair of rotor sprockets having a synchronizer therearound, the rotor sprockets driving a coupling mechanism coupling the power transfer from the serpentine member to gripper actuators on the rotor which articulate grippers at the rotor axis of rotation.

FIG. 19ais a partially cut-away section view along line 19 a-19 ain FIG. 19 showing one rotor (satellite) sprocket driving, by way of example, a pump and/or generator part of the power or energy transfer coupling between the serpentine member and the gripper actuators.

As seen in FIGS. 1 and 2, the power tong 6 may include three main sections mounted on a common axis A; namely a main drive section, a rotor, and a back-up jaw. Each of the sections contains actuators, as better described below. The main drive section 10 which provides at least part of a rigid stationary framework or stator frame is located above the rotor 22. The backup jaw 48, located below rotor 22, may also provide part of the stator frame. The rotor 22 rotates relative to the main drive and back-up jaw. Both the rotor and backup jaw clamp their respective sections of pipe. The rotor 22 is rotated by the main drive section 10 independently of the main drive section and backup jaw in the sense that the rotor 22 is self-contained, having on-board hydraulic and electric power generators to power on-board radial clamps or grippers (collectively herein referred to as grippers), and an on-board serpentine secondary power transmission, all configured to allow the insertion and removal of a pipe through a jaw opening from or into the center of the jaw, so that the pipe, when in the center of the jaw may be clamped, torqued, and spun about axis A of rotation of the rotor 22 while the other, oppositely disposed section of pipe is held clamped in the center of the back-up jaw 48.

As shown in FIGS. 1, 2 and 3 rotor 22 is housed within drive section 10, although this is not intended to be limiting as the rotor may be mounted so as not to be housed within the drive section and still work. The rotor 22 is cylindrical in shape and has an opening slot, which although illustrated as linear may be linear or non-linear, having a throat 38 for passing of a tubular along the slot thereby allowing the tong axis of rotation A to be selectively positioned concentric with pipe 8, provided the rotor 22 is rotated such that its throat 38 is aligned with the front openings 28 and 29 of the main drive section and back-up jaw, respectively. Center 40 of the yoke formed by the jaw and slot corresponds with axis A. The rotary jaw 22 has three gripper cylinders 44 a, 44 b, and 44 carranged radially, with approximately equal angular spacing around axis A, mounted between the two parallel horizontal planes containing rotor gears 30 aand 30 b. The number of gripper actuators, such as gripper cylinders 44 a-44 c, and associated grips or grippers may be more or less in number, so long as a tubular joint may be gripped or clamped at center opening 40.

A serpentine member such as serpentine drive belt 20 is driven by two serpentine drive motors 18, which may for example be hydraulic or electric motors. The serpentine member is mounted around so as to engage stator sprockets mounted on the stator frame. For example the stator sprockets may include drive sprockets 26 awhich are driven by serpentine drive belt 20 to collectively provide a secondary drive powering the grippers on the rotor 22. Drive sprockets 26 arotate serpentine drive belt 20 about idler sprockets 26 mounted to drive section 10. And the serpentine drive belt 20 also engages about rotor sprockets 32 a-32 fmounted on the rotor 22 as better described below. The rotor sprockets 32 aand 32 bmay be two generator drive sprockets. The rotor sprockets 32 cand 32 dmay be two pump drive sprockets. Rotor sprockets 32 eand 32 fmay be two idler sprockets. In the illustrated embodiment, which is not intended to be limiting as other embodiments discussed below would also work, the generator drive sprockets, that is, rotor sprockets 32 aand 32 b, transmit rotary power to generators 34. The pump drive sprockets, that is, rotor sprockets 32 cand 32 d, transmit rotary power to hydraulic pumps 36 by the action of serpentine drive belt 20 engaging the upper groove of rotor sprockets 32 a, 32 b, 32 cand 32 d. A synchronization belt, 28 a, connects the lower portions of the rotor sprockets 32 a-32 f. Thus as the rotor 22 rotates on axis of rotation A, even though serpentine drive belt 20 cannot extend across the throat 38 because such a blockage would restrict selective positioning of the pipe 8 along the slot into the tong, serpentine drive belt 20 wraps in a C-shape around the rotor sprockets 32 a-32 f. Serpentine drive belt 20, driven by drive sprockets 26 a, runs on pulleys 26, and on idler sprockets 26 band 26 cmounted to, so as depend downwardly from, main drive section 10. The extent of the C-shape of serpentine drive belt 20 provides for continual contact between serpentine drive belt 20 and, in this embodiment which is not intended to be limiting, a minimum of three of the rotor sprockets 32 a-32 fas the rotor rotates relative to the main drive section 10. The synchronization belt 28 amounted on the rotor maintains rotation of the individual rotor sprockets as they pass through the serpentine gap 29 seen in FIG. 4, that is, the opening between sprockets 26 band 26 c. Synchronization belt 28 asynchronizes the speed and phase of the rotation of each of the rotor sprockets 32 a-32 fto allow each of them in turn to re-engage the serpentine drive belt 20 after they are rotated across the serpentine gap 29 by the action of the rotor rotating relative to the main drive.

During operation of tong 6 the secondary drive (drive motors 18) and serpentine drive belt 20 run continuously to deliver power to the on-board pumps and generators by means of the rotor sprockets 32 a-32 d. Rotation of the rotor 22 by the operation of the primary drive acting on the pinions 56 and rotor gears 30 aand 30 bdoes not substantially affect the powering of the on-board accessories (pumps and generators) because drive belt 20 is run at substantially an order of magnitude greater speed than the speed of rotation of rotor 22. The rotation of the rotor only adds or subtracts a small amount of speed to the rotation of the rotor sprockets.

Upper rotor gear 30 aand lower rotor gear 30 bare parallel and vertically spaced apart so as to carry therebetween hydraulic pumps 36, generators 34, the rotor hydraulic system, rotor jaw electrical controls and the array of three radially disposed hydraulic gripper cylinders 44 a, 44 b, and 44 c, all of which are mounted between the upper and lower rotor gears 30 aand 30 bfor rotation as part of rotor 22 without the requirement of external power lines or hydraulic lines or the like. Thus all of these actuating accessories, which are not intended to be limiting, may be carried in the rotor 22 and powered via a nested transmission, nested in the sense that the C-shaped synchronization drive loop mounted on the rotor, exemplified by synchronization belt 28 a, is nested within so as to cooperate with the C-shaped serpentine drive loop mounted to the main drive, exemplified by serpentine drive belt 20.

Thus as used herein, a serpentine belt, such as the serpentine belt 20, driving a plurality of stator and rotor sprockets (as herein below defined), and as in the various forms of the stator and rotor sprockets found illustrated in all the figures herein, are herein referred to generically as a form of nested transmission. The nested transmission transfers power from the fixed stage to the rotational stage in a continuous fashion as, sequentially, one element after another of the rotational drive elements on the rotating stage are rotated through and across throat 38 and gap 29 allowing selective access of the tubular 8 to the center opening 40 of the stage.

For proper operation of the tong, it is desirable that the gripper actuators such as gripper cylinders 44 a-44 cclamp the tubular 8 substantially at, that is, at or near the rotational center axis of the tong. It can be readily seen that gripping the tubular 8 with a significant offset from the center axis would result in wobble or runout of the tubular when spinning in or out and could result in thread damage, excessive vibration, damage to the machine and inaccurate torque application.

It will be appreciated that the inboard ends of side gripper cylinders 44 aand 44 bmove in an arc as the gripper cylinders are extended or retracted. For the side gripper cylinders 44 aand 44 b, the geometry of reaction links 44 eis optimized to minimize deviation from the nominal gripper cylinder radial axis over the gripping diameter range to angles typically less than one degree. The gripper cylinders 44 aand 44 bwill however swing significantly from the nominal gripper cylinder radial axis, in the order of five degrees, when they fully retract to clear the throat 38. It is an advantage of the link design that it requires less stroke to clear the throat 38 due to the swing associated with the arc of reaction links 44 e, which ultimately allows a more compact rotor and hence a more compact tong. That is, the combination of the swing in direction C with the retracting stroke in direction D results in less of a stroke length required to clear throat 38 than merely using a retraction stroke without swing. The amount of swing is governed by the radius of arc E associated with rotation of the reaction links 44 eand the length of the required stroke in direction D.

The back-up jaw section 24 as shown in FIGS. 5, 5 a, 6 and 8 is typically mounted to a tong positioning system capable of holding the tong assembly level and enabling vertical and horizontal positioning travel. The tong may be pedestal-mounted on the rig floor, mast-mounted, track-mounted on the rig floor or free hanging from the mast structure. It may also be mounted at an angle for slant drilling application or with the pipe axis horizontal.

In the preferred embodiment, as seen in FIG. 10, the rotor hydraulic system 53 is a dual (high/low) pressure system or infinitely variable pressure system which produces high pressures (in the order of 10,000 psi) necessary for adequately gripping large and heavy-duty tubulars and for applying make-up or break-out torque, and lower pressures (2500 psi or less) to avoid crushing smaller or lighter-duty tubulars. Hydraulic pumps 36, rotationally driven as described above, are fixed-displacement, gear or variable displacement piston pumps. In the idle state, hydraulic pumps 36 charge one or more gas-filled accumulators 55 mounted in or on rotor 22 to store energy to enable rapid extension of the gripper cylinders 44 a-44 c. In this way, very fast gripping speeds may be achieved while keeping the power transmitted by the serpentine drive belt 20 drive low. That is, although the power supplied via the serpentine drive belt is small, the rotor hydraulic system must be able to intermittently supply a relatively large flowrate at low pressure for rapid advance of the gripper cylinders until they contact the tubular and also supply a low flowrate at very high pressure, in the order of 10,000 psi, to adequately grip the tubular for torquing operations.

In the schematic of the preferred rotor hydraulic system 53 of FIG. 10, system 53 has one or two gear or piston pumps 36 of relatively small capacity, within the power limitations of the serpentine drive belt. When there is no gripping demand, the pumps charge one or more gas-filled accumulators 55 to store energy for intermittent peak demands. The accumulators are optional, for the benefit of advance speed. The system is workable without accumulators provided the pumps are variable displacement. A load-sensing circuit with or without regenerative advance may also be used as would be understood by someone skilled in the art. A directional control valve 63 directs hydraulic pressure to the gripper cylinders. The directional control valve is solenoid-actuated with the solenoids controlled by the rotor control system. There are two flow paths from the directional control valve 63 to the extend side of the gripper cylinders. The first is the rapid-advance flow path which directs a large flowrate, in the order of thirty-five gallons per minute, from the pump(s) 36 and accumulator(s) 55 to the gripper cylinders at relatively low pressure, in the order of 2500 psi, for rapid extension of the gripper cylinders until they contact the tubular 8. The second is the high-pressure path in which pressure is regulated by a proportional pressure control valve 64 which is controlled by the rotary jaw control system of FIG. 11. The regulated pressure is supplied to an intensifier 65 which boosts the pressure by a factor in the order of 4:1 to supply high pressure, in the order of 10,000 psi, to the gripper cylinders. A check valve 66 prevents the high pressure fluid from flowing back into the rapid-advance low pressure flow path. The directional control valve 63 can also be solenoid actuated to direct fluid to the rod side of the gripper cylinders for retraction.

The use of high grip pressures, in the order of 10,000 psi, allows the use of compact gripper cylinders which results in a compact tong. By using the intensifier 65 to build the high grip pressure, no high pressure control valves are required.

It can be seen that in spite of the small input power, the hydraulic system can intermittently supply large flowrates for rapid grip cylinder advance and high pressures for high-torque operations. The system can regulate the grip pressure, adapting to the applied torque, for optimum gripping performance.

The rotor control system seen in FIG. 11 activates and de-activates the gripper cylinders at the operator"s discretion, regulates grip pressure and monitors system function without any power supply or control wires from or to the fixed part of the tong, because the rotor is fully rotatable and the open throat of the yoke precludes the use of any slip rings which are commonly used to transmit electrical power and control signals to a rotating element.

As seen in FIG. 11, one or two generators 34 are driven by the serpentine belt drive 20. They supply power, preferably 24 volts DC, to a programmable logic controller (PLC) 70, a radio communication link 71 and a number of sensors 73.

The radio communication link 71, which may advantageously be a Bluetooth™ device, communicates wirelessly with a similar radio communication link 72 mounted on the stationary section of the tong. The two radio communication links, 71 and 72, act as a wireless communication bridge between the main tong control system 74 and the rotor PLC 70.

The rotor PLC 70, as directed by the main tong control PLC 74, controls the output solenoids on directional control valve 63 to extend and retract the gripper cylinders 44 a-44 cand the proportional pressure control valve 64 to control the grip pressure. It also receives feedback from sensors 73 on the rotor for such parameters as (possibly including but not limited to) grip pressure, hydraulic pump pressures, grip position and hydraulic oil temperature.

When breaking out (unscrewing) drilling tubulars, it is often difficult to identify the axial location of the split where the two tool joints meet. It is imperative that the tong be positioned such that the split is located in the axial gap between the rotor grippers and the back-up jaw grippers. If either the rotor or the backup jaw grips across the split, the tool joint and the tong may be damaged and time will be wasted because the connection will not break out.

As shown in FIGS. 15 and 16, the actual face seam 200 between the mating connection shoulder faces 201 is only marginally visible when the connection is made up and it may be further obscured by drilling fluid. There is typically a shoulder bevel 202 adjacent to each shoulder face 201. The shoulder bevel 202 is typically machined at a 45 degree angle and has a radial dimension typically 2 to 6 mm. The two adjoining shoulder bevels 202 combine to form a connection split bevel V-groove 203. The connection split bevel V-groove 203 is usually sufficiently visible to identify the split axial location for placement of manual tongs in conventional drilling operations. But for a mechanized tong with its operator positioned several feet away from the pipe, it may be difficult to see. Furthermore, the tong may obscure the operator"s direct view of the split location. Time will be wasted in identifying the split location, traveling to it and verifying that the split is correctly located in the axial gap between the rotary and back-up jaws.

For automated pipe-handling operations, it is important for the machine to identify and travel to the correct axial location of the split without control intervention by the operator.

It can be seen that a reliable automated system to detect the location of the connection split would improve speed and efficiency of a mechanized tong and is mandatory for fully-automated tong operations.

A tandem configuration may be employed. That is, the optical tubular caliper can be accomplished with a pair of single point beam sensors positioned approximately 180 degrees apart, with each beam projected radially inward toward the tubular at the same elevation. Each sensor measures the radial distance to the pipe surface. The control system computes the sum of these distances. The difference between a fixed offset value and the computed sum represents the diameter of the tubular, approximately independent of the position of the tubular in the opening. The system can quickly and accurately measure the diameter of any tubular passing through the single point beams and transmit the diameter measurement to the tong control system. Furthermore, as the tong travels axially along the pipe, the tong control system can relate a series of such diameter measurements to the corresponding tong elevations as measured via the control system instrumentation described elsewhere. A diameter profile along the length can thus be created, effectively a virtual diameter versus axial position plot. The control system can compare this diameter profile to the known characteristic of the connection split bevel V-groove 203. When such a profile match is identified, the connection split is located and the corresponding tong elevation is recorded. The tong then travels the contact axial offset distance between the light band 705 axial mounting position and the desired split position between the rotary and back-up jaw grippers.

The control system is programmed to tune out irrelevant variations in the measured outside diameter, such as at the tool joint upset steps. It will also filter out diametral noise associated with surface irregularities such as hardbanding, tong marks or wear grooves.

As mentioned above, the power tong according to the present invention may be mounted in many ways on the drilling rig structure, or it may also be free-hanging from a cable. The mounting method ideally allows the tong to be accurately positioned around the tubular 8 at a large range of elevations, retracts a substantial distance from well center for clearance for other well operations, parks in a small area to minimize space usage on the drilling rig floor, keeps the tong level and allows the tong to be positioned to work at multiple locations such as the mousehole which may not be in the same plane as well center and the tong park location. The mounting system could be capable of rapid movement between working and idle positions but with smooth, stable motions. It should allow the operator to command horizontal or vertical movements or a combination.

Numerous tong or wrench mounting mechanisms exist in the industry. Most are Cartesian (horizontal/vertical) manipulators employing tracks, slides or parallelogram linkages for each motion axis. These mechanisms are simple to control because they directly actuate on the horizontal and vertical axes but they typically have a small range of motion which limits tong functionality and restricts mounting location on the drill floor. They have a large parked footprint which consumes scarce rig floor space and interferes with other well operations. And they have little or no capability to react torque applied to the tong or wrench by a top drive in the rig.

Thus in one preferred embodiment, a tong is preferably mounted on a manipulator 99 as shown in FIGS. 12aand 12b. A slewing base 100 is mounted to the drilling rig floor. A hydraulic slewing motor 101, via a gear reduction, can turn the slewing base up to three hundred and sixty degrees about the vertical axis. The internal bearings of the slewing base can support the weight and overturning moments of the manipulator structure and the tong. Slewing motor 101 may alternatively be electric, pneumatic or manually actuated.

The tong is pivotally mounted at the end of boom 103. The angle of the tong relative to boom 103 is controlled by linear actuator(s) 106. The inclination of the tong is monitored by angle sensor 109.

Various possible tong positions are selectively positioned between the extended operating position illustrated in FIG. 12aand the parked position of FIG. 12b. It can be seen that the manipulator 99 provides a large range of motion but can park the tong 6 with a small footprint.

The booms have significant lateral and torsional stiffness. This is advantageous over prior systems because the structure can react torque applied to the tong by a top drive in the rig, such as for back-up of drilling connection make-up. The tong can also apply torque to make up a bit restrained in the rig"s rotary table.

Manipulator 99 may be fully functional with manual controls for each of the four output actuators (slewing motor 101 and linear actuators 104, 105 and 106). However, it preferably has a control system as described below in which horizontal and vertical rates of tong travel are controlled in direct proportion to horizontal and vertical velocity commands by the operator and the tong is automatically kept level. The control system may also include the capability of optimized travel, including acceleration and deceleration control, to pre-defined locations.

The tong"s vertical and radial positions (relative to the slewing base) at any time are computed by the programmable logic control (PLC) 112 geometric constants and the boom 102 and 103 angles measured by angle sensors 107 and 108. The slewing orientation is measured preferably by an encoder 110 on the slewing drive. The tong"s three-dimensional position is therefore monitored at all times.

The preferred operators control console has a single 3-axis joystick 111 for control of the manipulator. The x-axis of joystick 111 controls the horizontal motions of the tong, the y-axis of the joystick 111 controls the vertical motions of the tong and the z-axis (handle twist) of the joystick controls the slewing motions of the assembly. The joystick commands may be discrete ON/OFF but are preferably analog/proportional on the x and y axes for finer control.

Horizontal motion of the tong requires movement of both boom 102 and boom 103, accomplished via linear actuators 104 and 105. The required output velocity signals to each of linear actuators 104 and 105 are computed in the PLC 112 in order to achieve the desired horizontal command velocity from the x-axis of joystick 111.

Similarly, vertical motion of the tong requires movement of both boom 102 and boom 103, accomplished via linear actuators 104 and 105. The required output velocity signals to each of linear actuators 104 and 105 are computed in the PLC 112 in order to achieve the desired vertical command velocity from the y-axis of joystick 111.

The control system may also have capability for automated travel to pre-defined locations such as well center, mousehole and parked position. When the operator commands automated travel to a desired pre-defined target location, the control system control acceleration, travel velocity, deceleration and landing speed for both horizontal and vertical axes to achieve optimum travel to the target, with minimum elapsed time and smooth, controlled motion.

In particular, in FIG. 18, serpentine drive belt 20′ is driven by at least one serpentine drive motor which may for example be at least one hydraulic motor. The serpentine drive motor drives at least one drive sprocket 26 a′ which, as before, provide a secondary drive via a plurality of rotor or satellite sprockets 32′ on rotor 22, and also drives a synchronizer between sprockets 32′ and a coupling such as pumps or generators, or a mechanical mechanism powering gripper actuators and corresponding grippers 44′, or directly acting on grippers 44′, on the rotor 22. As illustrated by way of example, a first drive stator sprocket 26 a′ rotates serpentine drive belt 20′ about a second stator sprocket which may be a second drive sprocket 26 a′ or an idler sprocket 26′ mounted to drive section 10. A tensioner 27 such as a tensioning idler sprocket, which may be considered a third stator sprocket, may be mounted to frame 60 so as to be resiliently biased against serpentine drive belt 20′ to tension the drive belt. A pair of satellite or rotor sprockets 32′ are mounted on the rotor 22. As seen in FIG. 18, the first and second stator sprockets are mounted on substantially opposite sides of the rotor. As the term is used herein, the first and second stator sprockets are arrayed substantially around the rotor. Third, fourth, etc stator sprockets would thus not have to be on one side or the other of the rotor, but would form part of the array of stator sprockets arrayed substantially around the rotor.

The rotor sprockets 32′ drive for example one or more on-board generators and/or one or more on-board hydraulic pumps (not shown in FIGS. 18 and 19). Synchronization belt 28 a′ may connect the lower or upper portions of the rotor sprockets 32′, with the serpentine drive belt 20′ then connecting the upper or lower portions of the rotor sprockets 32′ respectively. Thus as rotor 22 rotates about axis of rotation A even though serpentine drive belt 20′ cannot extend across the opening throat 38 because such a blockage would restrict selective positioning of the pipe 8 along the slot into the tong, serpentine drive belt 20′ wraps around or reaves so as to remain at all times in contact with at least one of rotor sprockets 32′. Drive sprockets 26 a′ are mounted to, so as to for example depend downwardly from, main drive section 10. As seen in FIG. 18a, the deflection of serpentine drive belt 20′ by the rotation of rotor sprockets 32′ provides for continual contact between serpentine drive belt 20′ and a minimum of one of the rotor sprockets as the rotor 22 rotates relative to the main drive section 10, wherein the deflection of serpentine drive belt 20′ tensions the portion of drive belt 20′ where it contacts tensioner 27. Upon return of the rotor sprockets to the position of FIG. 18, tensioner 27 takes up the slack in the drive belt 20′.

As seen in FIG. 19a, rotor 22, the rotor sprockets 32′, and one or more energy coupling 45 may be mounted within a rotary jaw frame 47 on, for example, bushings 49. Energy couplings 45 couple the energy being transmitted from the serpentine to the rotor sprockets 32′, and couples the energy to the grippers 44′ or gripper actuators (which in turn actuate the grippers). As stated above, energy couplings 45 may include pumps, generators, or mechanical drives such as direct mechanical linkages, but may also include the use of energy storage such as, without intending to be limiting, gas accumulators, batteries, capacitors, flywheels, which may then power actuation of the grippers when needed.

In Fig. 1, a fixed pulley 97 is installed on drilling derrick, steel cable 98 passes pulley, and the one end is connected by the suspension rod of sling and power tongs with openable jaws, and the other end is connected with bottle gouard moved by hands 93 or pneumatic puffer.The other end of bottle gouard moved by hands must be connected with the rig floor cross bar, and puffer also must be fixed on the rig floor.Regulate the suspension height of power tongs with openable jaws with bottle gouard moved by hands and puffer, so that make it just in time consistent with the joint height of drilling rod 99 on the well head.Power tongs with openable jaws 100 is connected with handover cylinder 95 by universal joint 94, transfers cylinder and is connected with stern post 96 by universal joint again.Because two universal joints are arranged, guarantee to transfer cylinder and only be subjected to axial force, limited because of the overtravel of transferring cylinder again, limit the pendulum angle of power tongs with openable jaws, thereby prevented more contingent accidents.

In Fig. 2, the power of power tongs with openable jaws is supplied with by hydraulic motor 105, drives sloth wheel gear 22 and then drives upper grip head 101 rotations through two grades of planet speed change mechanisms and two-stage gear reduction 110.Unsteady brake strap mechanism 103 is arranged in last pincers outside, and its column 55 is fixed on the housing 35, and stop screw 54 is arranged at its top.Be equipped with shedding mechanism 104 on the upper grip head 101.Lower pliers head 102 is contained in the housing 35, and the dial 51 of clamp mechanism is connected on the piston rod 48 that clamps cylinder 106 by pin 49, and resetting-mechanism 104 is also arranged on the lower pliers head.

At the middle part of power tongs with openable jaws suspension rod 86 is installed, the leading screw 76 on the suspension rod can be regulated the horizontal level of tong, inclination angle before and after front and back jackscrew 77 and 78 can be regulated.Suspension rod has the gas storage function, therefore the pressure meter 80 of indication air pressure is housed, and Pneumatic valve assembly 107 has been installed.Pressure meter 81 and control valve 82 and valve plate 83 are housed on the hydraulic motor 105.

The input pinion shaft 12 of high-grade central gear and reducing gear is with splined.Power drives gear wheel 21 by passing to reducing gear here, and then drives axle 20 and pinion 19, drives two sloth wheel gears by gear 19, so that drive the opening gear.Two air clutchs are shift and dispense with parking very easily.

In Fig. 7, the tong head of visible power tongs with openable jaws.Accept the opening gear 23 of sloth wheel gear power, supporting by the two kinds of rollers 109 and 108 on the tong housing 35, and drive upper grip head buoyancy body 34 by bearing pin 24 and square socket 26, the square hole 45 of square socket 26 and buoyancy body 34 has certain clearance, guarantees that buoyancy body is unsteady.Palate plate frame 27 is housed on buoyancy body, and the palate plate frame can rotate relative to buoyancy body, and the palate plate frame is fixed on the brake disc 25 of buoyancy body top by screw 28, and with its rotation.The leaf spring of being fixed by screw 30 31 is arranged on the palate plate frame, be screwed with location plug 29 on the palate plate frame above the leaf spring, the stop screw 32 of the restricted palate plate roller of palate plate frame is equipped with pincers tooth 33 on palate plate.Be split ring 36, be welded on the housing 35 that lower pliers head is installed on the housing, and palate plate frame 27 can rotate relative to housing by weld seam 38 below the opening gear.Adorning screw 30 and leaf spring 31 on the palate plate frame equally, and stop screw 32, location plug 29.The palate plate frame is fixed on the dial 51 by screw 37, rotates with dial.Pincers tooth 33 is housed on the palate plate equally.

In Fig. 9, shown that drilling rod has entered into the central authorities of pliers, bump on the plug 29 of location.The leaf spring 31 that is fixed on the palate plate frame by screw 30 is compressed, palate plate 44 is close on the MNM face of palate plate frame 27, ramp 39 is fixed on the buoyancy body 34 by screw 43 and wedge type nut 42, ramp has slope angle curved surface 46, be connected the central authorities that roller 40 on the palate plate 44 is close to ramp by pin 40, palate plate pin 41 can slide along the groove 47 of palate plate frame, and an end of groove 47 has stop screw 32.Two pincers teeth 33 are arranged on the palate plate.Palate plate and roller centre and opening vertical line have angle ∠ KOP, and its value is about 2 °～4 °.On buoyancy body, there is side"s cover 26 of three square holes 45 and opening gear to match, in order that transferring power, the spring base of four supportings in addition.Brake disc 25 at the buoyancy body outer mask.Brake disc and palate plate frame 27 are fixed into one.

In Figure 11, the unsteady upper grip head that can see power tongs with openable jaws is inserted in spring base 53 in the buoyancy body through hole, is tightened the screw that tightens at the gland 120 of buoyancy body through hole upper end, with gland on buoyancy body by screw and place an end in the buoyancy body through hole to be against the other end on the gland to be against spring 52 on the spring base, to be formed by the opening gear 23 of spring base supporting buoyancy body by buoyancy body 34, four.

In Figure 13, as seen power tongs with openable jaws to reset to breach mechanism be by the alignment pin 75 that is fixed on the buoyancy body 34, tighten detent mechanism shell 70 on brake disc 25 by screw, the detent mechanism shell is fixed on screw on the brake disc, and the first quarter moon location that is through in the detent mechanism outer casing through hole ships and resell on another market 71, place the upper end of shipping and reselling on another market, first quarter moon location to locate the position fixing handle 73 of the power transmission of shipping and reselling on another market by plane and first quarter moon, position fixing handle is fixed on first quarter moon location ships and resell on another market and goes up and prevent the ship and resell on another market nut of tenesmus of first quarter moon location, place position fixing handle cross through hole one end to be against the detent mechanism shell other end and be against alignment pin 72 on the spring, being placed on an end in the position fixing handle cross through hole is against the other end on the alignment pin and is against spring 74 on the plug, spring and alignment pin are enclosed in the plug that leans on screw thread and position fixing handle to link in the position fixing handle cross through hole, buoyancy body and brake disc are formed.

In Figure 15, the part of the unsteady brake strap mechanism of visible power tongs with openable jaws is formed situation.Two brake straps 56 are connected with connecting rod 59 by pin 57, right-hand thread screw 61 is connected with connecting rod 59 by pin 62 with left-hand thread screw 66, sliding sleeve 63 is spun on the right-hand thread screw by right-handed thread, regulating sleeve 65 is spun on the left-hand thread screw by the left-hand thread screw thread, and the dog screw that put spring 64 in sliding sleeve and regulating sleeve, is screwed on the regulating sleeve slides in the groove 67 of sliding sleeve.

From Fig. 2, Fig. 3, Figure 15, among Figure 16, the unsteady brake strap mechanism that can see power tongs is by brake disc 25, be coated on two brake straps 56 of brake disc side, be fixed on the housing 35 in order to the fixing column 55 of a looped end of brake strap, tighten stop screw 54 on the column top, pass another looped end of brake strap and be inserted in the pin 57 that brake strap is connected with connecting rod, one end connects two connecting rods 59 that the brake strap other end is connected with right-hand thread screw or left-hand thread screw by pin 62 by pin, with connecting rod with pin 62 joining right-hand thread screw 61 and left-hand thread screws 66, be spun on sliding sleeve 63 on the right-hand thread screw by right-handed thread, be spun on regulating sleeve 65 on the left-hand thread screw by the left-hand thread screw thread, be screwed in edge away guider screw in sliding sleeve groove 67 of its end on the regulating sleeve, place one end among regulating sleeve and the sliding sleeve to be against the sliding sleeve other end and be against spring 64 on the regulating sleeve, be through the sleeve 69 in the connecting rod through hole, be through in the sleeve endoporus by screw thread and be screwed in two pillars 62 on the housing, by the junction plate 58 of screw in compression on two pillars, compressing junction plate is screwed in institutes such as screw on the pillar and housing 35 and forms.

In Figure 17, shown the air-path control system of power tongs.This system be by gas supply line, have the gas storage effect suspension rod 86, be contained in pressure meter 80 on the suspension rod, transfer cylinder 95 and control the reversal valve of its action, the tight cylinder 106 of clamp and control the reversal valve of the reversal valve of its action, high-grade planetary control air clutch 4 and rapid-release valve 79, low-grade planetary control air clutch 7 and rapid-release valve 79, these two air clutchs, and control corresponding pipeline down etc. and formed.Reversal valve constitutes the control valve assembly.

In Figure 18, shown the hydraulic system of power tongs.The reversal valve 82 that this system is turned to by hydraulic motor 105, control hydraulic motor, the safety valve 87 that is contained in button loop assurance security of system, the pressure meter 81 that shows pressure and fuel feeding and unloading line are formed.

The flexible shift that power tongs with openable jaws of the present invention had, align palate plate automatically and clamp, reset to functions such as openings, it is very simple that the driller is operated.Used control valve member reduces to minimum degree, has improved reliability, the applicability of power tongs with openable jaws.

Embodiments of the present invention generally relate to systems and methods for local hydraulic power generation on an electric tong. Description of the Related Art

Tongs are devices used on oil and gas rigs for gripping, clamping, spinning, and/or rotating tubular members, such as casing, drill pipe, drill collars, and coiled tubing (herein referred to collectively as tubulars and/or tubular strings). Tongs may be used to make-up or break-out threaded joints between tubulars. Tongs typically resemble large wrenches, and may sometime be referred to as power tongs, torque wrenches, spinning wrenches, and/or iron roughnecks. Tongs have typically used hydraulic power to provide sufficiently high torque to make-up or break-out threaded joints between tubulars. Such hydraulic tongs have suffered from the requirement of a hydraulic power generator on the rig floor, necessitating big hydraulic hoses connecting the hydraulic power generator to the tong, causing contamination concerns and excessive noise. Moreover, due to the distance from the power generator to the tong, hydraulic tongs have suffered from reliability issues and imprecise control of the torque.

Electric tongs have been proposed. For example, U.S. Pat. No. 9,453,377 suggests retrofitting a conventional hydraulic power tong with an electric motor. The electric motor would then be used to operate the power tong for rotating or spinning a tubular during make-up or break-out operations. A separate electric motor is proposed to actuate lift cylinders between the power tong and the backup tong. Another separate electric motor is proposed for applying clamping force to the backup tong. However, electric power supply for a tong might be insufficient when extreme forces are required. Moreover, the multiplicity of electric motors may be impractical when costs are an issue.

Local hydraulic power generation on an electric tong may provide improved handling, greater reliability, and increased safety and efficiency at reasonable costs. SUMMARY OF THE INVENTION

In an embodiment a tong system includes a power tong for spinning tubulars; a first electric motor functionally connected to the power tong; a plurality of hydraulic power consumers including a backup tong for clamping a tubular string; a second electric motor functionally connected to the plurality of hydraulic power consumers; and electronics to drive the first electric motor and the second electric motor.

In an embodiment, a tong system includes a power tong for spinning tubulars; a plurality of hydraulic power consumers including a backup tong for clamping a tubular string; an onboard electric motor; and a switchbox providing at least two configurations of the tong system: in a first configuration, the onboard electric motor drives the power tong but does not supply hydraulic power to the plurality of hydraulic power consumers; and in a second configuration, the onboard electric motor does not drive the power tong but does supply hydraulic power to at least one of the plurality of hydraulic power consumers.

In an embodiment, a tong system includes a backup tong for clamping a tubular string; an onboard electric motor; and an onboard hydraulic power unit coupled to the onboard electric motor to supply hydraulic power to the backup tong.

In an embodiment, a method of making-up tubulars includes arranging a tong system in a hydraulic power configuration; supplying hydraulic power to at least one of a plurality of hydraulic power consumers to position a tubular for make-up; arranging the tong system in a rotary drive configuration; supplying at least one of torque and rotation to a power tong; wherein an onboard electric motor of the tong system supplies the hydraulic power when the tong system is in the hydraulic power configuration, and the onboard electric motor supplies the at least one of torque and rotation when the tong system is in the rotary drive configuration. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 4 illustrates a tong system that is configured to switch electric power between a rotary drive configuration and a hydraulic power configuration.

In some embodiments, onboard electric motors may be beneficially utilized to supply large power densities that are controllable with a variable frequency drive. For example, the speed and/or torque of an electric motor may be controlled to reach a predefined target torque and/or to keep a predefined torque profile. The torque of the electric motor may be proportional to the current that is regulated electronically by a variable frequency drive, while the speed may be in phase with the generated frequency. In one embodiment, miniaturized, controllable electric motors may be mounted on the tong system (i.e., “onboard”). In some embodiments, the onboard electric motors may be capable of producing output in the range of about 2 kW/kg to about 5 kW/kg. In some embodiments, the onboard electric motors may be between about 8 kg and about 12 kg, for example, about 10 kg. In some embodiments, the onboard electric motor may be coupled to one or more of a reducing gear, another gear stage for low gear, and a flameproof housing. In some embodiments, these combined components may be between about 64 kg and about 96 kg, which may still be lighter than similar power provide by a hydraulic system.

As illustrated in FIG. 1, a tong system 100 suitable for use on oil and gas rigs generally includes a backup tong 110 for gripping and/or clamping the tubular string and a power tong 120 for spinning the tubular. The backup tong 110 may generally be below the power tong 120. The backup tong 110 clamps the tubular string to provide an opposing force to the torque applied to the tubular from power tong 120. Consequently, the backup tong 110 may be characterized as generally having high torque at low rpm requirements. The power tong 120 spins the tubular during make-up/break-out operations. Consequently, the power tong 120 may be characterized as generally having high torque at high rpm requirements. The tong system 100 may also include one or more lift actuators 130 (e.g., a linear actuator cylinder) for vertically positioning the backup tong 110. The tong system 100 may also include one or more door actuators 140 for controlling the tubular access door 145. In embodiments discussed below, tong system 100 also includes one or more of a hydraulic power unit 150, power electronics 160, and/or a switchbox 180, to provide local hydraulic power generation.

In some embodiments, the average power required to operate a power tong 120 during one work cycle may be less than 10% of the maximum power. For example, FIG. 2 illustrates a graph 200 of the maximum torque values vs. rotation speed for a 50 k ft lbf power tong 120 in low gear and in high gear. It should be appreciated that the power of the tong may be limited by the available power of the hydraulic supply and by physical layout. In the example of FIG. 2, the rated pressure (that results in the maximum torque) may be about 200 bar, and the maximum volume flow rate the tong may accept may be about 100 liter/minute. Therefore, the maximum power that the system may be capable of would be about 33.33 kW. As illustrated in FIG. 2, the power tong 120 may operate in low gear at region 210, generating torque of between about 20 k ft lbf and about 60 k ft lbf. With the power tong 120 in low gear, the tubular rotates at up to about 5 rpm. Therefore, the maximum power requirement in low gear is about:

The power tong 120 may operate in high gear at region 220, generating torque of between about 4 k ft lbf and about 10 k ft lbf. Therefore, the maximum power requirement in high gear is about:

Likewise, when operating in the high gear region 220, the power tong 120 may provide higher torque at lower rpm with similar maximum power requirements:

The examples from Equations 1-3 are upper values which are normally only demanded for a short period of time. During an entire make-up cycle of about 120 seconds, the average power is about 10% of the maximum power requirement. Therefore, with the maximum power required in low gear region 210 or in high gear region 220 being approximately 14.2 kW and 17.0 kW respectively, the average power required in either of these regions is 1.4 kW and 1.7 kW, respectively, which is less than about 10% of the maximum power of the system (33.33 kW), and a local battery may be capable of supplying the power for the power tong 120 without significantly increasing safety concerns (e.g., risks of excessive heat in the explosive atmosphere of an oil rig). For example, peak power may be supplied to power tong 120 by a lithium titanate or lithium iron phosphate battery. Such a battery may supply about 1.2 kW/kg to about 2.4 kW/kg without excessive heating.

FIG. 3 illustrates a graph 250 of the torque and rotation speed required over a typical make-up cycle for a power tong 120. At the beginning of the make-up cycle, in region 260 (e.g., about first 5 seconds), the rotor may be slowly rotated in low gear to engage the tubular threads and confirm that the threading has engaged correctly. During the middle of the make-up cycle, in region 270, the rotor (now in high gear) speeds-up to the maximum speed (for example, as defined for this tubular type by the drilling contractor). The high rpm may be maintained for about 15 seconds until a reference torque is reached. For example, the reference torque may be selected to stop the tong well before the tubular shoulders engage. When the reference shoulder torque is reached, the power tong 120 is switched back to low gear. In region 280, the make-up may be done smoothly and/or continuously in low gear (e.g. for about the next 8 seconds). Lastly, the threads are secured in region 290 as indicated by rapidly increasing torque and decreasing rpm. The required power, which is the product of torque and turns, is normally less than half of the maximum power. Furthermore, the complete work cycle is more than 2 minutes, because bringing in another pipe, stabbing-in, and finally lowering the string into the well takes most of the time. Considering this, the average power is about 10% of the maximum power of the tong.

Electric power supply for a tong might be insufficient when extreme forces are required. Moreover, the multiplicity of electric motors may be impractical when costs are an issue. Therefore, a source of local hydraulic power is proposed. As illustrated in FIG. 1, tong system 100 includes local hydraulic power generation. As previously discussed, the tong system 100 includes a backup tong 110, a power tong 120, and one or more lift actuators 130. Tong system 100 also includes a hydraulic power unit 150. In some embodiments, hydraulic power for the backup tong 110 may be supplied by the hydraulic power unit 150. For example, the backup tong 110 may utilize high force to clamp cylinders to clamp the tubular string and thereby counterbalance the high torque of the power tong 120. In some embodiments, hydraulic power for the lift actuators 130 may be supplied by the hydraulic power unit 150. For example, the lift actuators 130 may utilize high force to vertically position (e.g., raise or lower) the backup tong 110 while it clamps the tubular string. In some embodiments, the volume of the hydraulic power unit 150 may be less than (e.g., about 10% of) that of conventional hydraulic power units which had been located proximate the rig floor. For example, a rig floor hydraulic power unit that is capable of producing up to about 35 kW-about 40 kW may have a volume of about 400 liters, while hydraulic power unit 150 may have a volume of between about 30 liters and about 40 liters, or in some embodiments less than about 50 liters. Hydraulic power unit 150 may include a tank with a submerged motor and a dual stage pump. Hydraulic power unit 150 may include a tank with a submerged motor and a pump with a booster. Hydraulic power unit 150 may include a tank with a submerged motor with a variable frequency drive. Hydraulic power unit 150 may include a tank with a submerged small motor with a hydraulic accumulator. In some embodiments, the hydraulic power unit 150 may supply power so that the cylinders (e.g., clamp cylinders of backup tong 110, lift cylinders of lift actuators 130) have fast action while having maximum pressure. Exemplary hydraulic power units 150 may include compact hydraulic power packs wherein the motor shaft of the electric motor also acts as the pump shaft.

In some embodiments, the hydraulic power unit may be powered by an onboard electric motor. This may allow for a single electric motor to be utilized both for the power tong and for backup tong. For example, a switchbox may decouple the rotor of the power tong when the hydraulic pump is activated. FIG. 4 illustrates a tong system 400 that can switch between a rotary drive configuration and a hydraulic power configuration. As illustrated, tong system 400 includes a hydraulic power unit 450 that includes an accumulator 451 and a pump 452 (which may include a reservoir tank (not shown)). Tong system 400 also includes an onboard electric motor 453. An exemplary onboard electric motor 453 may be a low voltage motor with integrated electronics. Hydraulic power unit 450 may supply hydraulic power to one or more hydraulic power consumers, such as the backup tong 410, the lift actuators 430, and the door actuators 440. Onboard electric motor 453 may also and/or alternatively supply torque and/or rotation to power tong 420. For example, switchbox 480 may switch the output of onboard electric motor 453 between the pump 452 and drivetrain 425 (e.g., a gearbox and a rotor) for power tong 420. In some embodiments, switchbox 480 may be configured to switch the output of onboard electric motor 453 to pump 452 to store hydraulic power in accumulator 451 while one or more of the power tong 420, backup tong 410, lift actuators 430, and/or door actuators 440 are inactive. In some embodiments, switchbox 480 may be configured to switch the output of onboard electric motor 453 to pump 452 to directly drive one or more of the backup tong 410, lift actuators 430, and/or door actuators 440. In some embodiments, tong system 400 may not receive hydraulic power from an external source (e.g., a hydraulic power unit on the rig floor). Specifically, backup tong 410 may only receive hydraulic power from local hydraulic power unit 450.

In some embodiments, onboard electric motor 453 may be selected to supply either (a) sufficient torque and rotation to power tong 420, as illustrated by the work cycle graphs of FIGS. 2-3, or (b) sufficient power to drive hydraulic power unit 450 between power tong work cycles, but not both at the same time, and no more than the maximum of the two. For example a DYNAX 60i motor includes integrated electronics while still being only about 14 kg. Consequently, onboard electric motor 453 may be small enough to not pose excessive risks (e.g., heat, noise, fuel consumption) in the rig environment.

Tong system 400 of FIG. 4 may also include electronics 460. The electronics 460 may include a charger 462, a programmable logic controller 464, a battery 466, and an inverter 468. Electronics 460 and/or inverter 468 may function as a variable frequency drive for onboard electric motor 453. Battery 466 may be a lithium iron phosphate battery and/or a lithium titanate battery. An exemplary battery 466 may be a 14 Ah Prismatic Pouch Cell, available from A123 Systems of Livonia, Mich. The battery may be, for example, between about 5 kg to 10 kg. The battery 466 may be contained in a flameproof housing. It is believed that no ATEX standard currently exists for batteries on tong systems, and further testing may be needed. Onboard electric motor 453 may be driven and/or controlled by electronics 460. For example, the torque of onboard electric motor 453 may be proportional to the current coming from the inverter 468. Likewise, the speed of onboard electric motor 453 may be in phase with the frequency of the current coming from the inverter 468. Onboard electric motor 453 may supply torque to power tong 420 in order to make-up to tubulars to a precise target torque while maintaining this torque for some time.

In some embodiments, programmable logic controller 464 may switch power supply to the consumers. For example, the battery 466 may alternatively charge and discharge, the onboard electric motor 453 may switch between the drivetrain 425 and the hydraulic power unit 450, and the sources of hydraulic power may be the pump 452 and/or the accumulator 451. At times during operations, each of backup tong 410, lift actuators 430, and door actuators 440 may be powered by one or more of the sources of hydraulic power. The programmable logic controller 464 may determine which power source supplies which consumer at any point in time during operations.

In some embodiments, the hydraulic power unit may be powered by a dedicated onboard electric motor. This may allow for a dedicated electric motor to be utilized for the power tong and a smaller, dedicated electric motor to be utilized for the hydraulic power unit. FIG. 5 illustrates a tong system 500 with separate, dedicated electric motors for the rotary drive configuration and the hydraulic power configuration. As illustrated, tong system 500 includes a hydraulic power unit 550 that includes an accumulator 551 and a pump 552 (which may include a reservoir tank (not shown)). Tong system 500 also includes a first electric motor 523 for the power tong 520, and a second electric motor 553 for the hydraulic power unit 550. The second electric motor 553 may be smaller than the first electric motor 523. In some embodiments, the second electric motor 553 may be about 1/10 of the size of the first electric motor 523. Both the first electric motor 523 and the second electric motor 553 may be otherwise similar to onboard electric motor 453. Hydraulic power unit 550 may supply hydraulic power to one or more hydraulic power consumers, such as the backup tong 510, the lift actuators 530, and the door actuators 540. First electric motor 523 may supply torque and/or rotation to power tong 520. Output of first electric motor 523 may supply power to drivetrain 525 (e.g., a gearbox and a rotor) for power tong 520. In some embodiments, output of second electric motor 553 may supply power to pump 552 to store hydraulic power in accumulator 551 while one or more of the backup tong 510, lift actuators 530, and/or door actuators 540 are inactive. In some embodiments, the output of second electric motor 553 may supply power to pump 552 to directly drive one or more of the backup tong 510, lift actuators 530, and/or door actuators 540. In some embodiments, while the second electric motor 553 and/or the pump 552 are inactive, the accumulator 551 may supply power to directly drive one or more of the backup