Abstract:
A bearing assembly comprises a bearing enabling a rotatable body to rotate about a rotational axis relative to a stationary body. The bearing includes a bearing inner ring and a bearing outer ring, each having at least first and second roller body tracks provided in or on non-parallel surfaces of the ring. The respective roller body tracks of the bearing outer ring are aligned with the respective roller body tracks of the bearing inner ring and a row of roller bodies is disposed between each of the respective sets of roller body tracks. At least one of the rows of roller bodies comprises one of tapered rollers and spherical rollers, at least one of the rows of roller bodies supports at least axial forces and at least one of the rows of the roller bodies supports at least radial forces.

Description:
CROSS-REFERENCE 
       [0001]    This application claims priority to European patent application no. 09 006 942.8, filed May 25, 2009, and to German utility model application no. 20 2010 002 282.7, filed Feb. 19, 2010, both of which are incorporated by reference as if fully set forth herein. 
       TECHNICAL FIELD 
       [0002]    The present invention generally relates to a bearing assembly, e.g., for a drilling rig, such as an oil drilling rig. Preferred embodiments concern a bearing assembly for a swivel or a top drive of a drilling rig. 
       KNOWN ART 
       [0003]    A known drilling rig is shown in  FIG. 1  and includes a rinse head or swivel head  1 , which is shown in more detail in  FIG. 2 . The swivel head  1  includes a swivel or base body  2 , which comprises a suspension bracket  3  (e.g., a hook), on which a cable of a lifting device can engage in order to raise and lower the assembly  1 . A support  4  for a drill pipe or drill string is disposed in the lower portion of the bearing assembly  1 . The drill pipe may be rotatably driven separately, e.g., by a kelly drive. In the alternative, a drive device for the drill pipe/string can be integrated into the swivel head, in which case, it is called a top drive. In any event, a bearing  5  is required to enable the support  4  with the drill pipe/string to rotate relative to the swivel body  2  about a rotational axis  6 . 
         [0004]    The swivel  1  enables a drilling fluid to be communicated, e.g., from a stationary, non-rotating fluid source to the rotating drill pipe or drill string. 
         [0005]    In the prior art, tapered roller thrust bearings are typically used to support the main axial loads that arise during the drilling process. In case of varying axial loads, a housing washer can be biased by springs. In the alternative to the tapered roller bearings, spherical roller thrust bearings (radially free) can be utilized. In some cases, the spherical roller thrust bearing is designed so that it can also support radial loads. For supporting the radial loads that arise during the drilling process, for example, two radial bearings (e.g., cylindrical roller bearings) are often utilized in the upper and lower portions, respectively. 
         [0006]    The previously-known embodiment shown in  FIG. 2  uses a cylindrical roller bearing as a radial bearing in the lower portion and a tapered roller thrust bearing for supporting the main axial loads in the middle portion. A tapered roller bearing that can support radial loads as well as axial loads in small amounts is mounted in the upper portion. Thus, the three bearings  5  or bearing functions are disadvantageously spread out over a relatively long distance in the axial direction of the swivel  1 . 
         [0007]    In the alternative, a spherical roller thrust bearing, which is designed to also support radial loads, could also be used in such an embodiment. Mutually-employed bearings, e.g., spherical roller thrust bearings and/or tapered roller bearings, are known. For supporting the opposing axial load, a cylindrical roller thrust bearing can also be utilized, wherein a radial cylindrical roller bearing is then utilized in the upper portion for supporting the radial load. 
       SUMMARY 
       [0008]    It would thus be desirable to provide a more compact bearing assembly. 
         [0009]    In addition or in the alternative, it would be desirable to provide a bearing assembly that can be mounted or assembled in a less complex manner. For example, it would be advantageous if a precise alignment of the different bearings is not required during the mounting or assembly process. 
         [0010]    In one aspect of the present teachings, bearing assemblies are taught that may have a relatively compact construction, e.g., a relatively short height in the axial direction and/or a relatively small outer diameter. 
         [0011]    In addition or in the alternative, the bearing assemblies may be relatively easy to mount and assembly, wherein the alignment complexity is reduced. 
         [0012]    In another aspect of the present teachings, a bearing assembly may preferably comprise a bearing inner ring consisting of one part or composed of two parts and a bearing outer ring consisting of one part or composed of two parts. At least two tracks are defined, e.g., machined, in the bearing inner ring as well as also in the bearing outer ring. At least two rows of roller bodies are disposed between the respective tracks and preferably at least one of the rows of roller bodies is selected from tapered rollers and spherical rollers. 
         [0013]    In preferred embodiments, one of the rows of the roller bodies can be formed and disposed exclusively for supporting forces acting in the direction of the axis (axial forces). In addition or in the alternative, both the bearing inner ring and the bearing outer ring can be formed in one-piece. 
         [0014]    In another aspect of the present teachings, at least one of the bearing rings can include at least one thread for connecting with a mounting part via a screw. 
         [0015]    In another aspect of the present teachings, one of the rows of roller bodies, preferably tapered rollers, is disposed so that they can support forces acting exclusively in the direction of the axis. 
         [0016]    In another aspect of the present teachings, one of the rows of roller bodies can be cylindrical rollers that are disposed so that they can support exclusively radial forces. 
         [0017]    In another aspect of the present teachings, one of the rows of roller bodies can be disposed between the tracks so that they can support axial as well as radial forces. In this case, the roller bodies supporting the axial and radial forces may be one of cylindrical rollers, tapered rollers or balls disposed at an angle to the axis of the bearing assembly. 
         [0018]    In another aspect of the present teachings, one or both of the bearing inner ring and the bearing outer ring may be provided with bores extending in the direction of the axis. Such bores may be used to affix the ring to a mounting part, e.g., via a pin, bolt, screw or, e.g., another type of projection extending through the bore into the mounting part. 
         [0019]    In another aspect of the present teachings, at least one track can be formed by or on a track ring that is biased by a spring element in the axial direction relative to the bearing ring carrying it. In a particularly preferred embodiment, the bearing inner ring may be one-part, the bearing outer ring may be two-parts and a track ring may be disposed in each of two parts of the bearing outer ring. One or both of the track rings may be biased in the axial direction by a spring element. 
         [0020]    In another aspect of the present teachings, the bearing inner ring or the bearing outer ring may include gear teeth for engaging a drive pinion that is driven, e.g., by an electric motor or other drive means, e.g., for rotating the drill pipe or drill string relative to the swivel body. 
         [0021]    The bearing assembly is preferably utilized in a swivel head for a drilling rig and the rotational axis is preferably disposed vertically during use. A bearing assembly of the present teachings is configured or designed, in more preferred embodiments, to be the sole bearing of the drilling rig swivel. 
         [0022]    In preferred embodiments, bearing assemblies according to the present teachings make it possible that all the forces, which arise during the drilling process, can be supported with a screwed-on bearing unit. 
         [0023]    In another aspect of the present teachings, the axial loads can be supported by one or by two thrust bearings, likewise the torque loading of the bearing assembly. A radial bearing supports the radial loads. 
         [0024]    A spherical roller thrust bearing also may be utilized with the present bearing assemblies. The two thrust bearings may be axially biased by springs. The shaft or support for the drill pipe can be connected together with the rotating inner ring via one or more screws. The housing (swivel body) of the bearing assembly also can be connected with the outer ring(s) via one or more screws. 
         [0025]    The inner ring as well as the outer ring can be embodied in a one-piece manner, for which assembly openings are provided in this case for inserting the roller bodies. 
         [0026]    In preferred embodiments, bearing assemblies according to the present teachings are relatively simple and cost-effective, because the bearing rings can be connected together with the mounting parts using screw connections. In this case, individual adjustments of the individual bearings may not be required after assembly. 
         [0027]    Further, it is preferable that the shafts and the housing tolerances have no influence on the bearing clearance. 
         [0028]    The present teachings allow, in certain embodiments, multiple bearings of the known art to be replaced by a single, relatively-compact bearing unit. 
         [0029]    While the present teachings are particularly applicable to vertical drilling rigs, bearing assemblies according to the present teachings can also be advantageously utilized in horizontal drilling applications, such as, e.g., tunnel boring machines. The present teachings are more generally applicable to any bearing operation, in which a rotatable body is rotatably supported relative to a stationary body and both axial and radial forces must be supported by the bearing. 
         [0030]    Further features, objects and advantages of the invention will be understood from the following description of exemplary embodiments and the appended claims in view of the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]      FIG. 1  shows a known drilling rig. 
           [0032]      FIG. 2  shows a known bearing assembly for the drilling rig of  FIG. 1 . 
           [0033]      FIG. 3  shows a radial cross-section through a representative bearing assembly according to the present teachings. 
           [0034]      FIG. 4  shows an alternate to the embodiment shown in  FIG. 3 . 
           [0035]      FIG. 5   a  to  FIG. 5   f  show schematic illustrations of different designs of bearings having a one-piece bearing outer ring and a two-piece bearing inner ring. 
           [0036]      FIG. 6   a  to  FIG. 6   h  show schematic illustrations of different designs of bearings having a one-piece bearing outer ring and a two-piece bearing inner ring or having a one-piece bearing inner ring and a one-piece bearing outer ring. 
           [0037]      FIG. 7   a  to  FIG. 7   e  show schematic illustrations of different additional designs of bearings having a one-piece bearing inner ring and a two-piece bearing outer ring. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    Each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide improved bearing assemblies, as well as methods for designing, constructing and using the same. Representative examples of the present invention, which examples utilize many of these additional features and teachings both separately and in combination, will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Therefore, combinations of features and steps disclosed in the following detail description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the present teachings. 
         [0039]    Moreover, the various features of the representative examples and the dependent claims may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. In addition, it is expressly noted that all features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original disclosure, as well as for the purpose of restricting the claimed subject matter independent of the compositions of the features in the embodiments and/or the claims. It is also expressly noted that all value ranges or indications of groups of entities disclose every possible intermediate value or intermediate entity for the purpose of original disclosure, as well as for the purpose of restricting the claimed subject matter. 
         [0040]    In  FIG. 3 , a first representative bearing  5  according to the present teachings is shown. This bearing  5  enables a support  4  (see  FIG. 2 ) for the drill pipe or drill string to rotate relative to the swivel body  2 . In this preferred embodiment, the support  4  rotates about the vertical axis  6 . 
         [0041]    The bearing  5  of  FIG. 3  includes a one-piece bearing inner ring  7  and a two-piece bearing outer ring  8 ′,  8 ″. The two parts  8 ′,  8 ″ of the bearing outer ring are connected by a screw connection. For this purpose, through-bores  20  and  21  may be provided for a notillustrated screw. 
         [0042]    At least two (in the present embodiment, three) tracks  9 ′,  9 ″,  9 ′″ are defined, e.g., machined, in the bearing inner ring  7 . Likewise, at least two (in the present embodiment, three) tracks  10 ′,  10 ″,  10 ′″ are defined, e.g., machined, in the bearing outer ring  8 ′,  8 ″. At least two (in the present embodiment, three) rows of roller bodies  11 ,  12  and  13  are disposed between the tracks  9 ′,  9 ″,  9 ′″ and  10 ′,  10 ″,  10 ′″, respectively. 
         [0043]    The part of the bearing, which is formed by the roller bodies  11 , is constructed as a tapered roller thrust bearing and is provided for supporting the axial forces that arise during the drilling process, i.e. forces acting in the direction of the rotational axis  6 . In the exemplary embodiment of  FIG. 3 , the part of the bearing with the roller bodies  13  is also formed as a pure thrust bearing, in this case as a cylindrical roller bearing. 
         [0044]    However, the part of the bearing with the roller bodies  12  is embodied as a pure radial bearing, e.g., as a cylindrical roller bearing that can support exclusively radial forces. The use of a tapered roller bearing (with the roller bodies  11 ) has the particular advantage that the outer diameter of the bearing can be smaller (for the same load bearing capacity) than in the case of a cylindrical roller bearing, which results due to the tapered contour of the roller bodies, i.e. the tapered roller bearings narrow in the direction towards the rotational axis. Furthermore, less skidding results, in particular at high rotational speeds, when using tapered roller bearings than for a cylindrical roller bearing, which advantageously results in less heating of the bearing and also less wear. 
         [0045]    For the attachment of the inner ring  7  to a mounting part (e.g. support  4  or swivel body  2 ), at least one thread  14  (of which only one can be seen) is defined, e.g., machined, in the inner ring  7 . In this exemplary embodiment, discrete track rings  16  and  17  are inserted into the bearing outer ring  8 ′ and  8 ″, respectively, e.g., in corresponding annular grooves defined in the respective rings  8 ′,  8 ″. The roller bodies  11  and  13  roll on the track rings  16  and  17 , respectively. Spring elements  18  and  19  are operatively disposed between the track rings  16  and  17  and the bearing outer rings  8 ′ and  8 ″ respectively supporting the track rings  16  and  17 . The spring elements  18  and  19  generate a spring force in the direction of the axis  6 , i.e. the axial direction. 
         [0046]    The three respective bearing functions are thus realized in a very compact way by the roller body rows  11 ,  12  and  13 , in which the respective tracks  9 ′,  9 ″,  9 ′″ for these roller body rows  11 ,  12 ,  13  are formed on adjacent surfaces of the bearing inner ring  7 . 
         [0047]    In  FIG. 4 , an alternative design of the first representative bearing  5  is shown. In this case as well, a tapered roller thrust bearing is formed by roller bodies  11 , for which the one-piece bearing inner ring  7  has a track  9 ′ and the two-piece bearing outer ring  8 ′,  8 ″ has a track  10 ′ in part  8 ″. Thus, the tapered roller bearing with the roller bodies  11  is again embodied as a pure thrust bearing, exactly as in  FIG. 3 , i.e. it does not support radial forces. In addition, a second part of the bearing with roller bearings  12  is provided for supporting combined radial and axial loads, wherein the inner ring track  9 ″ is defined, e.g., machined, directly in the inner ring  7 , while the corresponding outer ring track  10 ″ is defined, e.g., machined, in the bearing outer ring  8 ′. 
         [0048]    Thus, the part of the bearing with the roller bodies  12  is embodied as a cylindrical roller bearing, wherein the rotational axis of the cylindrical rollers is, of course, disposed at an angle α to the axis  6 . In this exemplary embodiment, this angle is approximately 45°; it can, however, assume other values, e.g., preferably between about 30-60°. 
         [0049]    In  FIGS. 5 ,  6  and  7 , different alternative embodiments of the proposed bearing  5  are schematically shown. 
         [0050]    In  FIGS. 5   a  to  5   f , respective embodiments are illustrated, in which a two-piece bearing inner ring  7 ′,  7 ″ is utilized, whereas the bearing outer ring  8  is embodied as one-piece. A tapered roller bearing is utilized as a main thrust bearing almost in every case. In  FIGS. 5   b  and  5   c , however, a spherical roller thrust bearing (with the roller bodies  11 ) is utilized as an alternative. 
         [0051]    In addition, a second bearing (with the roller bodies  12 ) is utilized in each case. In  FIGS. 5   a  and  5   b , it is a combined thrust and radial bearing in the form of a spherical roller bearing. In  FIG. 5   c , it is a pure cylindrical roller thrust bearing, because the spherical roller bearing with the roller bodies  11  can also support radial forces. In  FIG. 5   d , it is a tapered roller bearing and in  FIGS. 5   e  and  5   f  it is a cylindrical roller bearing, which can support combined axial and radial forces, because the axis of the cylindrical rollers  12  is positioned at an angle (of about 45°) to the axis  6 . 
         [0052]    In  FIGS. 6 and 7 , different embodiments with (in some, split) bearing outer ring  8 ′,  8 ″ and one-piece bearing inner ring  7  are shown, and in some with one-piece inner ring  7  and one-piece outer ring  8 . 
         [0053]    According to  FIG. 6   a , the embodiment according to  FIG. 3  is, in essence, shown once again. In  FIG. 6   b , a ball bearing with the balls  12  is utilized as a combined radial and thrust bearing, which can be embodied as an angular contact roller bearing or a four-point-contact bearing. The embodiment according to  FIG. 6   c  is closely related to the embodiment to  FIG. 3 . In the embodiment according to  FIG. 6   d , a one-piece bearing inner ring  7  as well as a one-piece bearing outer ring  8  is utilized; a suitable fill-slot for the balls  12  is thus necessary, but is not illustrated.  FIG. 6   e  is again similar to the embodiment according to  FIG. 3 . In the embodiment according to  FIG. 6   f , the bearing inner ring  7  has gear teeth  22  for directly rotationally driving the inner ring  7  (i.e. a “top drive” embodiment).  FIGS. 6   g  and  6   h  again show tapered roller thrust bearings  11  in combination with ball bearings  12 . 
         [0054]    In the embodiments according to  FIG. 7 , the bearing outer ring  8 ′,  8 ″ is again two-pieced and the bearing inner ring  7  is one-piece. It is again illustrated that different combinations of the bearing types are possible. Tapered roller bearings with tapered rollers  11  ( FIGS. 7   a ,  7   b  and  7   c ) and spherical rollers  11  ( FIGS. 7   d  and  7   e ), respectively, are utilized as main thrust bearings. The bearing with the roller bodies  12  supports, in most cases, combined axial and radial forces (exception:  FIG. 7   d ) and are embodied as cylindrical roller bearings ( FIGS. 7   a ,  7   b  and  7   d ), a tapered roller bearing ( FIG. 7   c ) or a spherical roller bearing ( FIG. 7   e ). The pressure angle of the tapered roller bearing is, in most cases, in the area of 45°, but can deviate therefrom. 
       REFERENCE NUMBER LIST 
       [0000]    
       
           1  Swivel 
           2  Swivel body 
           3  Suspension bracket 
           4  Support 
           5  Bearing 
           6  Axis 
           7  Bearing inner ring 
           7 ′ Bearing inner ring 
           7 ″ Bearing inner ring 
           8  Bearing outer ring 
           8 ′ Bearing outer ring 
           8 ″ Bearing outer ring 
           9 ′ Track 
           9 ″ Track 
           9 ′″ Track 
           10 ′ Track 
           10 ″ Track 
           10 ′″ Track 
           11  Roller body 
           12  Roller body 
           13  Roller body 
           14  Thread 
           15  Thread 
           16  Track ring 
           17  Track ring 
           18  Spring element 
           19  Spring element 
           20  Through-bore 
           21  Through-bore 
           22  Tooth structure 
         α Angle