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FIELD OF THE INVENTION  
         [0001]    The invention relates generally to pipe handling systems, and in particular to an apparatus for providing drill pipe to, and receiving drill pipe from, the work floor of a derrick or rig.  
         BACKGROUND OF THE INVENTION  
         [0002]    Drill strings of pipe for oil and gas wells are assembled or disassembled vertically on a derrick one joint at a time, and are stored horizontally on pipe racks situated on the ground adjacent the rig. The work floor of the rig is typically elevated substantially above the pipe rack such that transferring sections of pipe to and from the racks and the work floor is necessary, and further requires careful handling of the heavy pipe to protect the workers and the pipe.  
           [0003]    Conventional systems based on a boom having a pipe receiving trough in which pipe may be placed typically also include some way to assist with moving heavy sections of pipe along and out of such trough.  
           [0004]    A variety of pipe cars, skates, bumpers, conveyors, stops and other devices (e.g. U.S. Pat. No. 4,371,302) have been described to control the motion of sections of pipe between a rig and ground.  
           [0005]    For example, the applicant&#39;s Canadian application CA 2224638 relies on a spring loaded bumper mounted on the proximal end of a telescoping rod to push sections of pipe along the trough as well as to absorb the impact of pipe sliding down the trough toward the distal end thereof.  
           [0006]    U.S. Pat. No. 6,533,519 to Tolmon (‘519’) issued 18 Mar. 2003 teaches a carriage member separate from a pusher member, both driven on a single axis aligned with the center of a pipe receiving groove. Disadvantageously, &#39;519 and similar “ram based” designs that push a carriage member up the center of a trough require heavy, bulky hydraulic cylinders that are often restricted along the trough they can move a carriage, and further have limited response times such that the average speed of the carriage is low, causing pipe handling operations to take significant time.  
           [0007]    U.S. Pat. No. 3,143,221 to Blackmon (‘221’) issued 4 Aug. 1964 teaches a pipe car pulled and released by a cable, having 2 sets of side-mounted wheels each set having a common axle, the wheels running in a channel in a fixed track. Importantly, the track along which the pipe car is designed to roll is stationary and does not move vertically or longitudinally like the boom of most modern pipe handling systems. Disadvantageously, this wheeled pipe car design and other similar pipe car designs that are pulled by a single cable along a center line, although capable of running substantially the full length of the boom, are unstable and the wheels and axles tend to wear prematurely with the wheels binding in their guide tracks. A further disadvantage of the discrete wheel &amp; track based design is that the coupling of the pipe car to the pipe handling system takes place at only four discrete points on the tracks, at any given moment. Very significantly the stability of the 221 design is problematic when the track in which the wheeled pipe car rides must move between the ground and work floor levels such that a reinforced track and a braking assembly become necessary. No pipe car design incorporating such features and which provides a relatively inexpensive addition to a raiseable pipe-handling apparatus is known.  
           [0008]    The prior art in the oil field services industry has concentrated on teaching variations on center-line pushing devices covering only a portion of the boom length. Designs based on pipe cars having discrete wheels situated in tracks provide a limited coupling of the pipe carrying device (“car”) to a relatively fragile set of members, resulting in a design that is less reliable, less stable and less safe than might be achieved using similar components. Moreover, none of the prior art reviewed teaches a device that is driven in both directions on both sides, failing to address the risk of runaway pipe cars.  
           [0009]    Accordingly, there exists a real need for a pipe handling apparatus which provides such features as braking and ability to propel a pipe car in two mutually opposite directions, so as to improve modern pipe handling apparatus.  
         SUMMARY OF THE INVENTION  
         [0010]    In one broad aspect of the invention there is provided a pipe handling apparatus for presenting sections of pipe to a raised derrick work floor, comprising: a longitudinally extending base having a proximal end and a distal end, operable in a generally horizontal position, having a longitudinal cavity between the proximal and distal ends; a longitudinally extending boom adapted for nestable positioning in the cavity, further having a longitudinally extending trough extending laterally within the boom for receiving at least one section of pipe therein; an arm coupled to the boom for raising a proximal end of the boom out of the cavity to a position proximate the floor for the purpose of presenting at least one section of pipe to the floor; and a carriage slidably coupled to the boom and moveable longitudinally along the boom for moving pipe longitudinally along the trough. The longitudinally extending base typically comprises a framework, having a catwalk around the longitudinal cavity to permit access to the trough, together with a suitable power supply and controls.  
           [0011]    In a refinement of the above aspect, the trough further has first and second opposite sides, and the carriage comprises: a base member, having a distal end and a proximal end and laterally extending across the trough between first and second opposite sides and slidably coupled to the boom for longitudinal movement along the boom; and a pipe engaging device for engaging at least one pipe to assist movement of the pipe longitudinally along the trough. The carriage apparatus further comprises, in a preferred embodiment, a carriage drive assembly for longitudinally moving the carriage along the boom, including brakes for controlling and arresting the motion of the carriage along the boom.  
           [0012]    In a further refinement, the carriage drive assembly comprises a motor adapted for turning gears, or sprockets and chains, or pullies and belts, or spindles and cables each to facilitate movement of the carriage along the boom, such may further include an idler or other assembly for tensioning the chains, or belts, or cables.  
           [0013]    In a further refinement of the invention, the boom has a first side and a second opposite side; and the base member has a first edge and a second edge each outwardly extending to surround respectively a portion of each of the first and second sides of the boom so as to permit slidable securement of the base member to the boom. Further wherein the pipe engaging device comprises a rigid plate member secured to the base member in proximity to the distal end thereof for contacting pipe. Further wherein the rigid plate member includes means for reducing damage to the pipe, which may comprise elastomeric or other material applied to the rigid plate member to assist in preventing damage to pipe that is transported in the carriage.  
           [0014]    In yet a further refinement of the invention, the carriage has means for releasably engaging the boom so as to prevent: undesired longitudinal movement of the carriage along the boom and/or undesired lateral movement of the carriage off the boom. The carriage further includes means for securing at least one section of pipe to the carriage during the movement of the base member along the boom.  
           [0015]    In a further embodiment of the invention there is further provided an idler carriage member, longitudinally separated along the boom from said carriage, and slidably coupled to the boom and moveable longitudinally along the boom for assisting movement of pipe longitudinally along the trough when pipe is engaged with the drive carriage.  
           [0016]    Each carriage member further, in a preferred embodiment, comprises means for reducing friction and facilitating movement of the base member along the boom, which in a preferred embodiment comprises a plurality of rollers situate between the base member and the trough. Examples of alternate means for reducing friction include: liquid lubricants such as oil, gases such as air or an inert gas under pressure, and opposing electromagnetic fields.  
           [0017]    In a further aspect, the carriage apparatus of the present invention, contemplates a wide-track, double-edge surround guide pair, with a low-profile base that is slideably coupled to a reinforced boom that also operates as a track, and a single or dual drive-line for bidirectional motion under power. Advantageously, by moving in the pipe trough the apparatus of the present invention achieves a full range of longitudinal motion while eliminating the cavity of older pipe car designs and reducing the pressure applied to the surface on which the apparatus glides. Further, a significant advantage results over the slower moving hydraulic pusher assemblies in that the average speed of the carriage of the present invention is higher permitting pipe handling operations to be accelerated.  
           [0018]    According to a preferred dual drive-line implementation, the apparatus of the present invention is made more reliable and further stabilized since either drive-line may propel the carriage. Each drive-line adds to the mass of the entire assembly, creating an inertial or runaway dampening effect in the event that power is lost to either the drive motor or to the braking assembly. Advantageously, overhanging channel members are provided which prevent disengagement of the carriage with the trough thereby overcoming the problem of the limited coupling achieved in designs having only four discrete points on tracks, by substantially fully encompassing both sides of a reinforced boom along the entire length of the carriage being coupled thereto, resulting in more extensive coupling to the trough. Further, the positioning of the drive-lines on both sides of the carriage results in additional force securing the carriage to the boom at the same time as resisting the twisting action to which a single center-point attachment is more prone.  
           [0019]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate preferred embodiments of the method, system, and apparatus according to the invention and, together with the description, serve to explain the principles of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    The present invention, in order to be easily understood and practised, is set out in the following non-limiting examples shown in the accompanying drawings, in which:  
         [0021]    [0021]FIG. 1 is an illustration of one embodiment of the system of the present invention.  
         [0022]    [0022]FIG. 2. is an illustration of some elements of the apparatus of the present invention.  
         [0023]    [0023]FIG. 3 is an illustration of one embodiment of the apparatus of the present invention shown together with elements of one embodiment of the drive assembly therefore.  
         [0024]    [0024]FIG. 4 is a close-up perspective view of one embodiment of the apparatus of the present invention together with some elements of a drive assembly therefore.  
         [0025]    [0025]FIG. 5 is an end-view of one embodiment of the apparatus of the present invention seated on rollers in a trough together with some elements of a drive assembly therefore.  
         [0026]    [0026]FIG. 6. is an illustration of an alternate embodiment to that of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]    Reference is to be had to FIGS. 1-6 in which identical reference numbers identify similar components.  
         [0028]    Referring to FIG. 1 there is illustrated a pipe handling system, denoted generally as  100  shown having base  110  mounted on undercarriage assembly  105  stabilized by legs  112  when in operation. Boom  120  is shown with proximal end  121  in a raised position moving toward a derrick work floor (not shown) with distal end  122  gliding along cavity  115  guided by track means (not shown), as actuating means  130  raises boom  120  out of cavity  115 . Trough  140 , having pipe  148  therein, extends longitudinally along boom  120  and may be formed therein or fastened thereon, but in either case trough  140  is adapted for receiving carriage assembly  150  adapted to be driven bi-directionally between the distal end  122  and the proximal end  121  of boom  120 .  
         [0029]    As shown in FIG. 1, carriage assembly  150  carries the distal end of pipe  148 . The proximal end  121  of boom  120  is raised by any suitable actuating means  130 , one embodiment of which comprises pivoting arm  131  and suitable linkage  132  actuated by hydraulic ram  133 , for the purpose of presenting pipe  148  together with collars, or the like (not shown) laying in trough  140 , to the rig floor for further handling, which process is commonly referred to as the “pick up” sequence. To return from the rig floor to ground, pipe  148  is lowered into proximal end  121  of boom  120  at the level of the rig floor and glides down trough  140  until it comes to rest against plate member  216  or pipe engaging member  220  (see FIG. 2) on carriage assembly  150  suitably positioned along boom  120 . Actuating means  130  then lowers boom  120  with pipe  148  therein, such that in its fully lowered or “laid down” position boom  120  nests inside base  110 . Although base  110  is illustrated in a mobile embodiment having any suitable undercarriage assembly  105 , a person of skill in the art would understand that base  110  may also be of the stationary variety.  
         [0030]    Referring to FIG. 2 there is illustrated an embodiment of carriage assembly  150 , showing base member  210  having formed therein a pipe receiving area  215  that conforms to trough  140  in boom  120 . At one end of base member  210 , one embodiment of pipe engaging member  220  is shown fastened to base member  210  in any suitable manner (e.g. bolted or welded) for the purpose of engaging one end of pipe  148  placed in receiving area  215 .  
         [0031]    Although pipe engaging member  220  has been illustrated as a simple “butt plate” at the distal end of base member  210 , which plate is used for pushing or catching sections of pipe  148  respectively sitting or arriving into receiving area  215 , it will be apparent to a person of skill in the art that by modifying pipe engaging member  220  to have a suitable passage there through combined with means for securing pipe  148  to receiving area  215  (e.g. electromagnets that could engage or release by remote control) would permit pipe engaging member  220  to be situated at different longitudinal positions along base member  210 . Also illustrated formed in or coupled to base member  210  is one embodiment of catch  230  (shown in FIG. 2 as a double-edge surround guide pair) for slidable coupling to and releasable engagement of base member  210  with boom  120 .  
         [0032]    According to a preferred embodiment, base member  210  of carriage assembly  150  includes an auto-centering trough design and an elastomeric lining  218  that each advantageously significantly enhance the safety of pipe handling. Trough  140  has a substantially v-shaped cross-section that tolerates a “pitch and roll” of approximately 30 degrees (whereas 10 degrees is the industry standard at which off-shore drilling rigs shut down operations because of the risk that conventional trough designs will release pipe) at the same time as facilitating pipe  148  “finding center” and resting stably in trough  140  rather than rocking back and forth before coming to rest as it would in a substantially circular cross-sectional trough. By further adding to pipe receiving area  215  of base member  210  a coating, layer, matting or other lining  218  of elastomeric material having a corrugated or similar surface to absorb kinetic energy and resist having pipe  148  rock or otherwise move once in trough  140  two advantages result. First, the safety of operation of system  100  is enhanced. Second, carriage assembly  150  may be used to pull pipe  148  away from the derrick as pipe  148  is lowered from the drill rig&#39;s “blocks” into trough  140 . Advantageously, the ability to drag pipe with the full-travel range, high-speed carriage assembly  150  permits system  100  to remove pipe  148  from the derrick sufficiently quickly to allow the blocks to move free and true thereby avoiding having the blocks hit the derrick causing damage thereto necessitating the repair thereof.  
         [0033]    Lining  218  may be applied to pipe receiving area  215  in a number of different ways (e.g. adhesive, spray-on, bolts, press fit) in a number of different orientations that depend on the particular form of lining  218  in use. According to a preferred embodiment lining  218  has a corrugated surface of ridges and is applied with those ridges oriented parallel to the direction of travel of carriage assembly  150  along boom  120 .  
         [0034]    According to an alternate embodiment of pipe engaging member  220  (shown in FIG. 6) spring-loaded, hinged, safety hood means may operate to semi-securely maintain an end of pipe  148  in receiving area  215  while the rest of pipe  148  is being lowered into trough  140 . As the blocks are used to lower pipe  148  into carriage assembly  150  an end of pipe  148  contacts pipe engaging member  220  prior to the rest of the tube making contact with trough  140  during the interstitial period between which contacts being made pipe  148  may not be aligned with trough  140  such that it rocks longitudinally on boom  120  causing said end of pipe  148  to bounce upward in and possibly to exit receiving area  215 . Advantageously as pipe  148  is lowered into receiving area  215  of carriage assembly  150  an end of pipe  148  contacts back plate  221  causing it to pivot about connection  222  triggering spring  223  to close hood member  224  over the distal end of pipe  148  thereby to semi-securely restrict the movement of said end of pipe  148  within receiving area  215 . As the blocks lower pipe  148  fully into trough  140  the distal end of pipe  148  pushes carriage assembly  150  towards the distal end  122  of boom  120 , and with pipe engaging member  220  having been triggered, if the weight of the blocks causes the distal end of pipe  148  to attempt to pop out of receiving area  215 , then pipe  148  is less likely to escape such that system operational safety is enhanced.  
         [0035]    Referring to FIG. 3 there is illustrated pipe handling system  100  including carriage drive assembly  300  comprising: motor  310 , brakes  315 , sprockets  320 , chain  325 , chain guides  330 , and tensioning idler  340 . Base member  210  connects to chain  325  at coupling points  350  proximate catch  230 . As motor  310  drives chain  325  about sprockets  320 , chain  325  causes carriage assembly  150  to move along boom  120  incrementally between proximal end  121  and distal end  122  either causing or allowing pipe  148  (not shown) to move along trough  140 . According to one embodiment of the apparatus of the present invention motor  310  is fastened to boom  120  and then coupled to carriage assembly  150  by any suitable combination of elements. For example, but not in limitation, motor  310  may be coupled by any of: sprocket and chain, pulley and belt, or spindle and cable to base member  210  permitting the propulsion of carriage assembly  150  along boom  120 . Similarly, any suitable control system (manual or automatic) may be used to cause motor  310  to engage or disengage, accelerate or decelerate carriage assembly  150  at suitable times and in a safe manner.  
         [0036]    Motor  310  of carriage drive assembly  300  may be any rotating: hydraulic, electric, pneumatic, gasoline, diesel, propane, steam or other motive source capable of developing sufficient power to move the subject pipe. Further, motor  310  may be mounted to boom  120  at either the proximal end  121  or the distal end  122 , however according to a preferred embodiment motor  310  is mounted inside boom  120  at proximal end  121  thereof in order to permit easy service of motor  310  when the distal end  122  of boom  120  is nested in cavity  115  and the proximal end  121  of boom  120  is only slightly raised out of cavity  115  for safe and easy access from base  110 . Motor  310  may be reversible (permitting “engine braking”) or it may “free-wheel” permitting carriage assembly  150  to return to the distal end of boom  120  under the weight of pipe in the trough, but it would in that embodiment typically be accompanied by a form of brake or clutch adapted to limit the acceleration of carriage assembly  150  as it returns to the distal end of boom  120 .  
         [0037]    According to another embodiment of the apparatus of the present invention, motor  310  may be fastened to the carriage base member  210 , rather than to boom  120 , in which case at least one motor  310  may be direct-drive coupled to boom  120  by an assembly of interacting gears (not shown) driving carriage assembly  150  along boom  120  against a toothed track fastened to boom  120  and substituted for guide  330 . Either rotating or linear motors having suitable directional control and power supply switching means would be applicable to such embodiment.  
         [0038]    In coupling base member  210  to motor  310  any suitable clutch, gear reduction, or other power transfer assembly (not shown) together with suitable activation control means may also be used to smooth out the motion and adjust the (weight carrying) capacity of carriage assembly  150 . Similarly any suitable frictional or electromagnetic braking system applied at any suitable point (e.g. the motor hub or the chain, cable, or belt) whether in disc brake or drum brake format and having suitable means to control the activation and release thereof may be used to prevent runaway action by carriage assembly  150 .  
         [0039]    Suitable guides  330  and tensioning idler  340  may be operated with or without adjuster  360  (e.g. a hydraulic ram or worm gear shaft) to ensure that sufficient tension is applied to chain  325  (or suitable cable or belt) permitting the smooth, predictable motion of carriage assembly  150 . Further, to facilitate operator ease of use stopping carriage assembly  150  at an appropriate (depending upon the presence of an idler carriage) location relative to proximal end  121  any suitable trip switch, electric-eye, or marker flag or combination thereof may be connected to boom  120  or trough  140  according to whether manual or automatic control is available with the subject embodiment of system  100 .  
         [0040]    By omitting pipe engaging member  220  from the embodiment of carriage assembly  150  illustrated in FIG. 2, an idler carriage  380  having substantially the same profile results. Typically the idler carriage  380  is not connected to the drive assembly (FIGS. 3-5) permitting it to free-wheel on boom  120  relative to carriage assembly  150 . How the carriages are positioned relative to one another depends on whether or not pipe engaging member  220  permits pipe to pass through carriage assembly  150  or to terminate against pipe engaging member  220 , but the idler carriage would typically be situated proximally relative to carriage assembly  150 . According to an alternate embodiment idler carriage  380  may be connected a fixed distance from carriage assembly  150 , permitting the reduction of friction (of a range of known pipe lengths transported in the resulting dual carriage assembly) by keeping both ends of any pipe or other material or equipment away from the surface of trough  140 .  
         [0041]    Referring to FIG. 4 there is illustrated an embodiment of elements of drive assembly  300  of carriage assembly  150  situate in trough  140  on boom  120 , according to which a belt member  325  has been used in place of chain  325  of FIG. 3. A person of skill in the art of machine design would understand that any suitable belt  325  (e.g. toothed or smooth) together with a compatible set of transfer elements  320  (e.g. sprockets or pulleys) may be used according to the capacity of carriage assembly  150  required for the weight of pipe  148  being handled by the subject embodiment of system  100 . As carriage assembly  150  moves along boom  120  belt  325  attached thereto at coupling points  350  is stabilized and directed by guides  330  keeping the moving belt  325  proximate boom  120  to avoid interference with base  110  or arm  131  as boom  120  moves vertically relative to cavity  115  and longitudinally relative to base  110 . According to a preferred embodiment of the system of the present invention guides  330  are coated or lined with strips of plastic, vinyl or other non-metallic material having suitable wear-resistance advantageously causing chain  325  (or belt or cable) to operate more quietly and wear less quickly.  
         [0042]    Referring to FIG. 5 there is illustrated an end-view of one embodiment of select elements of drive assembly  300  for base member  210  situate in trough  140  on boom  120 . Pipe engaging member  220  is shown as a solid “butt plate” embodiment used for pushing or stopping and terminating pipe  148  in receiving area  215 . Base member  210  is isolated from trough  140  by any suitably positioned plurality of rollers  515  thereby advantageously reducing operating friction and wear. Base member  210  may also be isolated from trough  140  by any suitable cushion of fluid (e.g. air or oil) or field effect. Catch  230  is illustrated as a pair of channels attached to or formed in the sides of base member  210  in order to surround each edge  145  of trough  140  fastened to boom  120  for the purpose of both maintaining belt  325  adjacent boom  120  and preventing base member  210  being pulled too far away from trough  140  and unintentionally decoupling boom  120 , advantageously stabilizing the operation of drive assembly  300  and enhancing safety. Coupling points  350  may be implemented below (as shown in FIG. 5), through, or above belt  325 . According to a preferred embodiment of the system of the present invention each pair of edges  145  is carefully sized, aligned and mated to each pair of catches  230  to ensure that carriage assembly  150  advantageously runs free and true along boom  120  to avoid binding, jerky operation, and premature wear.  
         [0043]    A dumping assembly (not shown) may be integrated into base  110  for receiving and ejecting, from base  110 , pipe  148  ejected from trough  140  onto base  110 . Further, an operator enclosure (not shown) that is weatherproof or chemical safe may be added to base  110  to permit workers to continue to handle pipe in hostile conditions. And, boom  120  may further comprise a telescoping “stinger” for extending the effective reach of boom  110  beyond proximal end  121 .  
         [0044]    Undercarriage assembly  105  having stabilizing legs  112  may comprise: a suitable wheel assembly  106 , frame means integrated with or coupleable to base  110 , at least one axle, suspension means, and towing or self-propulsion means, whereby wheel assembly  106  is coupled to the frame by the suspension connected to at least one axle, and the towing means is adapted for moving apparatus  100 .  
         [0045]    The terms and expressions employed in this specification are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions to exclude any equivalents of the features shown and described or portions thereof, and it is recognized that various modifications are possible within the scope of the invention claimed. Although the disclosure describes and illustrates various embodiments of the invention, it is to be understood that the invention is not limited to these particular embodiments. Many variations and modifications will now occur to those skilled in the art of machine design and drill pipe handling. For full definition of the scope of the invention, reference is to be made to the appended claims.

Summary:
A pipe handling apparatus for raising and lowering pipe to and from a raised derrick work floor. The apparatus comprises a longitudinally-extending base, with a longitudinally-extending cavity therein. An elongate, longitudinally-extending boom member is provided, which is adapted for raising out of and nestable positioning in such cavity. The boom member has a longitudinally-extending trough therein on an upperside surface thereof, adapted to receive at least one section of pipe. At least one arm member is coupled to the boom member for raising a proximal end of such boom member. A carriage member, slidably coupled to the boom member, is moveable longitudinally along the boom in the trough. The carriage member is adapted to engage and slidably transport one end of the pipe along the trough. Motive means are provided to permit powered movement of the carriage member along the boom.