Patent Publication Number: US-10316597-B2

Title: Tubular clamp system

Description:
BACKGROUND 
     Field 
     Embodiments of the disclosure relate to a tubular clamp system for handling tubulars. 
     Description of the Related Art 
     A tubular clamp system is often used in conjunction with a crane located on an oil and gas rig to handle one or more tubulars, such as to build multiple stands of tubulars. The tubular clamp system and the crane are used to make up or break out, and move the tubulars between well center and a racking board. Conventional tubular clamp systems use direct powered jaws to grip the tubulars. 
     However, in the event of a loss of power, these conventional tubular clamp systems will lose grip and drop any tubular that it is supporting, which can cause harm to rig personnel and/or damage surrounding equipment. Also, there is potential of slippage of the tubular from the tubular clamp system as a prime mover mechanism of the direct powered clamps begins to wear, or alternatively the potential of over clamping and crimping the tubular. Lastly, if a crane begins to lift a tubular that is still being gripped by the tubular clamp system (for example due to an operator&#39;s failure to disengage the tubular clamp system) then the tubular clamp system can be overloaded and damaged from further use. 
     Therefore, there exists a need for new and improved tubular clamp systems. 
     SUMMARY 
     In one embodiment, a tubular clamp system comprises a boom structure and a clamp mechanism coupled to the boom structure. The clamp mechanism comprises a carriage assembly and a gripper assembly coupled to the carriage assembly. The gripper assembly includes a pair of jaws movable into engagement with a tubular by a lead screw that is rotatable by a first actuator. The pair of jaws are configured to grip and lift the tubular by a thrust nut that is coupled to the lead screw and is rotatable by a second actuator. 
     In one embodiment, a clamp mechanism comprises a carriage assembly; and a gripper assembly coupled to the carriage assembly, wherein the gripper assembly includes a pair of jaws movable into engagement with a tubular by a first actuator, and wherein the pair of jaws are configured to grip and lift the tubular by a second actuator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a tubular clamp system having a clamp mechanism according to embodiments described herein. 
         FIG. 2  is an isometric front view of the clamp mechanism of  FIG. 1 . 
         FIG. 3  is an isometric back view of the clamp mechanism of  FIG. 1 . 
         FIG. 4  is a side view of the clamp mechanism of  FIG. 1 . 
         FIG. 5  is an isometric view of the gripper assembly of  FIGS. 2-4 . 
         FIG. 6  is a top view of the clamp mechanism in a first position, not engaging a tubular. 
         FIG. 7  is a top view of the clamp mechanism in a second position, engaging the tubular. 
         FIG. 8A  is a sectional front view of the clamp mechanism engaging but not gripping the tubular. 
         FIG. 8B  is a sectional side view of the clamp mechanism of  FIG. 8A . 
         FIG. 9A  is a sectional front view of the clamp mechanism engaging and gripping the tubular. 
         FIG. 9B  is a sectional side view of the clamp mechanism of  FIG. 9A . 
         FIG. 10A  is a sectional front view of the clamp mechanism engaging but not gripping the tubular due to a pull or push of the tubular up through the clamp mechanism. 
         FIG. 10B  is a sectional side view of the clamp mechanism of  FIG. 10A . 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized with other embodiments without specific recitation. 
     DETAILED DESCRIPTION 
     Embodiments of the disclosure relate to a tubular clamp system for handling tubulars on an oil and gas rig. The tubular clamp system includes a clamp mechanism having a gripper assembly and a carriage assembly. The gripper assembly includes two opposing jaws movable by lead screws. A low-torque actuator (e.g. a first actuator) will rotate the lead screws to drive the two opposing jaws into engagement with the outer perimeter of a tubular. The jaw actuator does not provide full clamp force but merely brings the jaws into contact with the outer surface of the tubular. 
     A torque thrust actuator (e.g. a second actuator) separate from the jaw actuator may be used to lift a lever arm that rotates a thrust nut to further drive the lead screw and the two opposing jaws into gripping engagement with the tubular. The torque thrust actuator provide a clamp force on the tubular up to a force that equals the weight of the tubular, times the mechanical advantage of the lever arm, times the wedge geometry of the lead screw. As the torque thrust actuator pushes on the torque levers beyond the rotational torque required to clamp and overcome the weight, the gripper assembly and the clamped tubular will lift off the carriage assembly and may trigger a switch that will signal positive clamp and support of the tubular being handled. 
     The weight of the tubular is the actuating force of the clamp mechanism while the actuators are merely supporting the live load of the tubular being lifted, and not a direct clamp force. Due to the characteristics of the lead screw, the lead screw is self-locking and will support the clamp force for as long as the tubular is being supported/handled with or without power to the clamp mechanism. The independent movement of the gripper assembly and the carriage assembly connected by the torque thrust actuator via the lever arm of the clamp mechanism allows for the external lifting of the clamped tubular that can unload the weight and reverse the force on the lever arm, auto releasing (unscrewing) the thrust nut and allowing for fail-safe release of the tubular. 
       FIG. 1  is an isometric view of a tubular clamp system having a clamp mechanism  100  coupled to a boom structure  105 . The boom structure  105  may be coupled to an oil and gas rig such that it is movable horizontally in the X-direction and/or vertically in the Z-direction. A portion of the boom structure  105  that the clamp mechanism  100  is coupled to is movable by an actuator, referred to herein as a piston/cylinder assembly  111 , to extend and retract the clamp mechanism  100  horizontally in the Y-direction. The clamp mechanism  100  is movable by another actuator, such as a piston/cylinder assembly and/or a cable/pulley assembly, to raise and lower the clamp mechanism  100  along a length  110  of a portion of vertically extending beams  115  of the boom structure  105 . The portion of the boom structure  105  and/or the clamp mechanism  100  can be moved by any type of hydraulic, pneumatic, electric, and/or mechanical actuated assemblies and are not limited to movement by piston/cylinder or cable/pulley assemblies. 
     In operation, the clamp mechanism  100  is configured to grip, raise, and lower a tubular relative to the boom structure  105 . For example, a portion of the boom structure  105  may be extended by the piston/cylinder assembly  111  to grip a tubular with the clamp mechanism  100  and then retracted back. The clamp mechanism  100  may then be lifted up along the length  110  of the beams  115  to lift the tubular vertically. Lastly, the boom structure  105  with the clamp mechanism  100  gripping the tubular may be moved laterally to position the tubular in a pipe deck or a racking board. 
       FIG. 2-4  are various views of the clamp mechanism  100  of  FIG. 1 .  FIG. 2  is an isometric front view of the clamp mechanism  100 .  FIG. 3  is an isometric back view of the clamp mechanism  100 .  FIG. 4  is a side view of the clamp mechanism  100 . 
     The clamp mechanism  100  includes a first member such as a gripper assembly  200  coupled to a second member or carriage assembly  205 . The carriage assembly  205  includes a plurality of rollers  300  (shown in  FIG. 3 ) that help facilitate movement of the clamp mechanism  100  along the beams  115  of the boom structure  105  shown in  FIG. 1 . 
     The clamp mechanism  100  includes a low torque actuator  210  (e.g. a first actuator) that is operably coupled to a pair of gripper jaws  215 . The actuator  210  may be coupled to one or more shafts  305  (shown in  FIG. 3 ), and each shaft  305  may be coupled to a first sprocket  220 . The first sprocket  220  is coupled to a second sprocket  225  by a flexible drive member  230  (shown in dashed lines in  FIG. 2 ) such as a chain. 
     In operation, the actuator  210  rotates the one or more shafts  305  and the first sprocket  220 , and the flexible drive member  230  rotates the second sprocket  225  which causes the gripper jaws  215  to move toward each other or away from each other (in the X-direction) to clamp onto a tubular or release a clamped tubular, respectively. The carriage assembly  205  and the gripper assembly  200  may be coupled together by a torque thrust assembly  400  (shown in  FIG. 4 ) that may comprise a torque thrust actuator  405  (e.g. a second actuator), an arm  815  retractable into and extendable from the torque thrust actuator  405 , and pins  410 , among other support members described below. 
       FIG. 5  is an isometric view of the gripper assembly  200  of  FIGS. 2-4 . The carriage assembly  205  is not shown in  FIG. 5  in order to show details of the gripper assembly  200 . 
     The torque thrust assembly  400  includes the pins  410  coupled to support members  500 . The support members  500  are coupled to a center pin  505  that is coupled to the torque thrust actuator  405 . The center pin  505  may be a gimbal mechanism that provides rotation of the torque thrust actuator  405  about an axis normal to an axis  515  of the gripper assembly  200  (e.g. the axis of a tubular to be gripped). The support members  500  and pins  410  are not shown on the torque thrust assembly  400  on the left side of the torque thrust assembly  400  of  FIG. 5  for further clarity of the torque thrust actuator  405 . 
     In operation, the actuator  210  (shown in  FIGS. 2 and 3 ) is activated which rotates the second sprocket  225 . The second sprocket  225  rotates a lead screw  520  about an axis  530  which rotates within a sleeve  525 . The axis  530  may be normal to the axis  515  of the gripper assembly  200 . The lead screw  520  also rotates relative to a thrust nut  535 . The relative rotation of the lead screw  520  and the thrust nut  535  thrusts the sleeve  525  that causes the gripper jaws  215  to move toward each other and contact an outer surface  540  of a tubular  545  (shown in phantom). The actuator  210  applies a low-torque to the lead screw  520  such that the gripper jaws  215  engage and contact the outer surface  540  of the tubular  545  but do not provide a grip sufficient to support the tubular  545 . 
     The actuator  210  closes the gripper jaws  215  against the outer surface  540  of the tubular  545 . The torque thrust actuators  405  provide the gripper jaws  215  with a gripping force sufficient to support and lift the tubular  545 . The actuator  210  provides a first torque-to-thrust value to the gripper jaws  215  and the torque thrust actuators  405  provide a second torque-to-thrust value to the gripper jaws  215  such that the second torque-to-thrust value is greater than the first torque value. 
       FIGS. 6 and 7  are top views of the clamp mechanism  100  showing the clamp mechanism  100  in a first, unclamped position and a second, clamped position engaging the tubular  545 , respectively. 
     In  FIG. 7 , the gripper jaws  215  are engaged with the tubular  545  by the actuator  210  that moves the gripper jaws  215  toward each other. The low torque of the actuator  210  does not provide a sufficient gripping force to the gripper jaws  215  to support the tubular  545  but does bring the gripper jaws  215  into contact with the tubular  545  of any given diameter. The tubular  545  is not effectively gripped by the gripper jaws  215  based solely on the activation of the actuator  210 . 
       FIGS. 8A and 8B  are cross-sectional views of the clamp mechanism  100  engaged but not gripping the tubular  545 .  FIGS. 9A and 9B  are cross-sectional views of the clamp mechanism  100  engaged and gripping the tubular  545 .  FIGS. 10A and 10B  are cross-sectional views of the clamp mechanism  100  engaged but not gripping the tubular  545  due to the tubular  545  being pushed or pulled through the clamp mechanism  100 . 
       FIGS. 8A, 9A, and 10A  are sectional front views of the clamp mechanism  100  in different operating positions taken along line A-A of  FIG. 7 .  FIGS. 8B, 9B, and 10B  are sectional side views of the clamp mechanism  100  in different operating positions taken along line B-B of  FIG. 7 . 
     In  FIGS. 8A and 8B , the gripper jaws  215  are engaged with the outer surface  540  of the tubular  545  utilizing only the actuator  210 . As shown in  FIGS. 8A and 8B , a support plate  800  of the gripper assembly  200  (e.g. upper support plate) is disposed on a support plate  805  of the carriage assembly  205  (e.g. lower support plate). A wrench plate  810 , which may be part of the torque thrust assembly  400 , is coupled between the thrust nut  535  and the arm  815  of the torque thrust actuator  405 . The wrench plate  810  may include a tool interface that interfaces with an outer surface of the thrust nut  535  (e.g. a hex shape). In this position, the arm  815  is retracted into the torque thrust actuator. 
     The arm  815  is coupled to the wrench plate  810  at a point that is offset from the axis  530  of the lead screw  520  by a distance  818 . When actuated, the arm  815  of the torque thrust actuators  405  applies a force to the wrench plate  810  at the offset distance  818  about the axis  530  which primarily acts to lift the weight of the tubular  545  as further described with respect to  FIGS. 9A and 9B . 
     In  FIGS. 9A and 9B , the gripper jaws  215  are engaging and gripping the outer surface  540  of the tubular  545  utilizing only the torque thrust actuators  405  with a sufficient force to grip and lift the tubular  545 . Once the gripper assembly  200  has gripped and lifted the tubular  545  off the carriage assembly  205 , the entire clamp mechanism  100  can be raised or lowered by the boom structure  105  along the length  110  of the beams  115  (shown in  FIG. 1 ) to raise or lower the tubular  545 . The weight of the tubular  545  loads the clamp mechanism  100  to maintain the grip by the gripper assembly  200 . 
     The torque thrust actuator  405  is actuated (e.g. pressurized by a pressurized fluid) to extend the arm  815 , which torques the thrust nut  535  via the wrench plate  810  against the lead screw  520  and forces the gripper jaws  215  via the sleeve  525  further into engagement against the outer surface  540  of the tubular  545  to grip the tubular  545 . The arm  815  of the torque thrust actuators  405  applies a force to the wrench plate  810  at the distance  818  offset from the axis  530  such that the weight of the tubular  545  is proportional to the force that torques the thrust nut  535  and thrusts the gripper jaws  215  against the engaged tubular  545 . This results in a torque-to-thrust mechanical advantage that “lifts” the gripped tubular  545  and the gripper assembly  200  off of the carriage assembly  205 , signaling a positive grip on the tubular  545  where the grip force is a direct function of the weight of the tubular  545 . 
     The gripper assembly  200  provides a constant proportional grip force relative to the weight of the tubular  545 , which is equal to a constant coefficient of friction that can be controlled by the geometry of the lead screw  520  and the length of the wrench plate  810  connected to the arm  815  of the torque thrust actuator  405 . The gripper assembly  200  will always grip just enough to lift the tubular  545 , no more no less, based on a predetermined friction constant. 
     In the lifted position, the support plate  800  of the gripper assembly  200  is lifted up from the support plate  805  of the carriage assembly  205  by a distance  900  allowing for the live load of the tubular  545  to be fully supported through the wrench plate  810  and the torque thrust actuator  405  of the carriage assembly  205 . As shown in  FIG. 9B , the arm  815  of the torque thrust actuator  405  is extended from the position shown in  FIG. 8B . 
     In  FIGS. 10A and 10B , the gripper jaws  215  are engaging but not gripping the outer surface  540  of the tubular  545  as the gripper assembly  200  is raised enough off the carriage assembly  205  so that the torque thrust actuator  405  coupled to the wrench plate  810  is not supporting enough live load sufficient to grip and support the tubular  545 . 
     In the event of the tubular  545  being pulled through the gripper jaws  215  by some external lifting apparatus, as would be the case in a hand-off operation or the pushing of the tubular  545  onto a drill floor, the gripper jaws  215  and gripper assembly  200  would be raised further off of the carriage assembly  205 , which moves the wrench plate  810  down relative to the gripper assembly  200  reversing the wrench plate  810  torque about the axis  530 . Since the arm  815  remains fully extended and coupled to the wrench plate  810 , then as the wrench plate  810  is pulled away, the arm  815  will pull down on the wrench plate  810  and cause it to rotate the thrust nut  535  in the opposite direction to back out the lead screw  520  and the gripper jaws  215  to release the grip on the tubular  545 . This acts as a fail-safe mechanism so that the tubular  545  can be pulled or pushed up through the gripper jaws  215  and automatically released from the gripper assembly  200  without causing damage to any of the equipment involved. The gripper jaws  215  however can remain engaged on the tubular  545  with just enough force to keep the tubular  545  captured and prevent it from toppling over. 
     The clamp mechanism  100  as described herein provides a gripper assembly  200  that can clamp a wide size range of tubulars, and lift and transfer the tubulars to other tubular handling equipment. The clamp force is a function of the tubular weight, which provides a suitable amount of grip force without crushing lighter/thinner walled tubulars or under clamping heavier/thicker walled tubulars. The gripper assembly  200  will not drop or lose grip on the tubular upon loss of power to the clamp mechanism  100 . 
     While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure thus may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.