Abstract:
A renewable bearing is for a tong including a housing and an engagement assembly. The bearing has a monolithic upper bearing element having a substantially planar upper surface and a monolithic lower bearing element having a substantially planar lower surface. The upper and lower bearing elements are configured to mount inside the housing with a substantially same outer horizontal profile as the upper bearing element. The upper bearing element and the lower bearing element define a central open area. The upper bearing element and the lower bearing element have an inner section define a radial recess opening to the central opening and for receiving the engagement assembly. The upper bearing element and the lower bearing element have outer sections that form a bearing portion radially intermediate the engagement assembly.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is directed to a TONG BEARING and in particular, to a machinable TONG BEARING that may be reconditioned for multiple uses and an extended useful life. 
         [0003]    2. Description of the Prior Art 
         [0004]    Tong systems are utilized in the oil well industry for attaching to and tightening various types of rods and tubing. Such tongs are utilized with a backup system that holds one element while a second element is gripped by the tong and rotated to connect and disconnect the two elements. 
         [0005]    A typical tong includes a housing around a gripping portion of the tong, with a gripping portion being driven and rotating relative to the housing. Conventional tongs utilize a series of bearing elements to facilitate rotational movement with less friction and wear. Such rollers, ball bearings or other conventional bearings are subject to the harsh conditions encountered at a well or drilling site. Therefore, such single use conventional bearings are subject to wear and/or failure, requiring frequent replacement. Moreover, in order to ensure smooth and continuous operation, multiple bearings are required at multiple positions spaced apart on both the top and bottom of the tong housing around the gripping assembly. The maintenance and replacement of the large number of bearings is both time consuming and expensive. Moreover, the maintenance required and high rate of failure can cause extended down time for the tong, affecting reliability, causing additional delays and adding to operational costs. 
         [0006]    It can be seen then that a new and improved bearing system is needed for tongs. Such a bearing system should eliminate the large number of bearings and small parts currently needed. Moreover, the bearing system should provide for greater reliability and less down time. Such a bearing should be easily removed and interchanged with other bearings. Moreover, the utility of such a bearing is improved if a bearing element can be reconditioned and used again. The present invention addresses these as well as other problems associated with tong bearings. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a tong bearing, and in particular to a renewable tong bearing. The tong includes a housing and drive elements as well as a gripping portion. The bearing includes an upper bearing element and a lower bearing element. Each of the bearing elements includes a generally rounded planar base portion and may include an open end or is closed to form a center opening. An inner annular raised portion is spaced radially outward from the center opening and extends downward from the base for an upper bearing element and upward from the base for a lower bearing element. An outer annular raised portion is adjacent the inner raised annular portion and extends downward from an upper bearing element and upward for a lower bearing element in somewhat tiered configuration. Outer walls form a lip around the outer annular raised portion and engage one another when the upper and lower bearing elements are placed aligned on top of one another. The bearing elements also include a flattened end portion forming a planar wall extending vertically and forming an opening when the upper and lower bearing elements are placed together for receiving drive train elements extending between motors and the gripping portion. 
         [0008]    The bearing elements are renewable and are made of a low friction material that is suitable for machining. Therefore, when the bearing elements develop flaws or become worn, the elements may be removed, the surfaces refinished and placed back into the tong for further use. When the satisfactory surfaces are again achieved, the bearing elements may be reused. To make up for lost thickness, shims may be placed in the tong housing and provide sufficient thickness for the bearing. 
         [0009]    The large single bearing eliminates the need for a high number of rollers or individual bearing elements and also provides for renewing and reusing the bearing elements. Moreover, the machinable material provides a low friction surface while also providing for refurbishing the elements to extend the useful life of the bearing. The exact configuration and geometry may be varied depending upon the type of tong and its application. Moreover, the upper and lower bearing elements may be mirror images of one another, or for some applications the bearing may need a dedicated upper element and a dedicated lower element. Moreover, depending upon the gripping portion and tong used, the raised portions and/or the outer lip may or may not be required. In some embodiment, lubrication channels are formed in the bearing to facilitate the spread of lubricants. 
         [0010]    These features of novelty and various other advantages that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings that form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Referring now to the drawings, wherein like reference letters and numeral indicate corresponding structure throughout the several views: 
           [0012]      FIG. 1  is an exploded top perspective view of a tong housing with the top of the housing removed with a bearing according to the principles of the present invention; 
           [0013]      FIG. 2  is a top perspective view of the bearing and the tong housing shown in  FIG. 1 ; 
           [0014]      FIG. 3  is a top plan view of the bearing and the tong housing shown in  FIG. 1 ; 
           [0015]      FIG. 4  s a bottom plan of the bearing and housing shown in  FIG. 2 ; 
           [0016]      FIG. 5  is a top perspective view of an upper bearing element for the bearing shown in  FIG. 1 ; 
           [0017]      FIG. 6  s a bottom plan view of the upper bearing element shown in  FIG. 5 ; 
           [0018]      FIG. 6A  s a bottom plan view of an alternate embodiment of the upper bearing element; 
           [0019]      FIG. 7  is a side elevational view of the upper bearing element shown in  FIG. 5 ; 
           [0020]      FIG. 8  is a top plan view of the upper bearing element shown in  FIG. 5 ; 
           [0021]      FIG. 9  is a side sectional view through the bearing and tong housing shown in  FIG. 1 ; 
           [0022]      FIG. 10  is an exploded view of the tong housing and bearing shown in  FIG. 1  with shims added; 
           [0023]      FIG. 11  is a side sectional view of the tong housing and bearing shown in  FIG. 10 ; 
           [0024]      FIG. 12  is a perspective view of a second embodiment of a bearing element according to the principles of the present invention; 
           [0025]      FIG. 13  s a bottom plan view of the bearing element shown in  FIG. 12 ; 
           [0026]      FIG. 14  is a side elevational view of the bearing element shown in  FIG. 12 ; 
           [0027]      FIG. 15  is a top plan view of the bearing element shown in  FIG. 12 ; 
           [0028]      FIG. 16  is a perspective view of the bearing element shown in  FIG. 12  and a portion of the housing. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    Referring now to the drawings and in particular to  FIGS. 1-4 , there is shown a tong  100  according to the principles of the present invention. The tong  100  is shown as an open face tong with an open end  110  but it can be appreciated that the present invention is also applicable for closed face tongs as explained hereinafter. The tong  100  includes a tong housing  102  and a bearing  104 . The tong housing  102  is shown with the top cover portion removed for clarity. In addition, the tong  100  includes various drive elements such as may be described in U.S. Pat. No. 8,281,691, entitled TONG ASSEMBLY, which is incorporated herein by reference. By modifying the shape and/or dimensions, the bearing of the present invention can be adapted for use with other types of tongs. The housing  102  includes a drive section  106  and a gripper section  108 . The tong housing  102  includes a base  112  and an outer wall  114 . The gripper section of the housing  108  also includes a curved wall portion  116  providing for rotation of gripping elements to manipulate tube or rod elements. The curved wall portion  116  also forms an opening to the drive section  106  of the tong housing  102  to permit insertion of drive train elements extending from the drive section  106  to the gripping elements and the bearing section  108 . This arrangement is also shown for a closed head tong in  FIG. 16 , described herein below. 
         [0030]    As shown in  FIGS. 1 and 2 , the bearing  104  includes an upper bearing element  120  and a lower bearing element  140 . The bearing elements  120  and  140  are configured for engaging one another at their periphery along an intermediate horizontal plane to form the bearing  104 . In the embodiment shown, the upper bearing element  120  is identical to the lower bearing element  140 . Therefore, the elements  120  and  140  may be interchanged and a supply of a single type of replacement bearing elements may be used without requiring a dedicated top or bottom element. However, in other embodiments the upper bearing element may have a different configuration than the lower bearing element. 
         [0031]    Referring to  FIGS. 5-9 , the upper bearing element  120  is shown. It can be appreciated however that upper bearing element  120  is identical to the lower bearing element  140  in the embodiment shown and the upper bearing element  120  may simply be flipped over to provide a lower bearing element  140 . Although only the upper bearing element  120  will be described, other than orientation, the description applies equally to the lower bearing element  140 . The bearing element  120  includes a base  122  and defines an open end  124 . The open end  124  leads to a center open portion  126 . The center opening  126  is configured for receiving gripping elements that engage rods, tubing and other elements to be gripped and rotated. Spaced radially outward from the inner edge of the base  122  of the center open portion is an inner annular raised portion  128 . The raised portion  128  extends downward for an upper bearing element  120  and an inner annular raised portion  148  extends upward for a lower bearing element  140 . An outer annular raised portion  130  is adjacent and radially outward from the inner annular raised portion  128 . The outer annular raised portion  130  extends downward further than the inner annular raised portion  128  for an upper bearing element while an outer annular raised portion  150  extends upward for a lower bearing element  140 . An outer wall  132  forms a lip that extends yet further downward than the outer annular raised portion  130  on the upper bearing element  120 . An outer wall portion  152  for a lower bearing element  140  extends upward and is configured to engage the outer wall portion  132  of the upper bearing element  120 . The outer wall portions  132  and  152  therefore form a vertically continuous curved wall when the bearing is assembled. The base  122 , the inner annular raised portion  128 , the outer annular raised portion  130  and the outer wall  132  form a terraced surface on the underside of the upper bearing element  120 . The bearing elements  120  and  140  are generally annular but include a flattened end portion  134 . The end portion  134  forms a planar vertical surface with an opening  136  to provide access for tong drive train elements that insert through the opening  136 . This arrangement is seen more clearly in  FIG. 16   
         [0032]    In a configuration mirroring the upper bearing element  120 , the lower bearing element  140  also includes a bearing base  142 , an open end  144 , forming an open center  146 . The lower bearing element  140  includes an inner annular raised portion  148  situated next to an outer annular raised portion  150  and an outer wall  152 . The lower bearing element includes a flattened end portion  154  and a drive train access opening  156 . Therefore, the base  142 , the inner annular raised portion  148 , the outer annular raised portion  150  and the outer wall  152  form a terraced surface on the top of the lower bearing element  140 . 
         [0033]    The bearing  104  operates in a very harsh environment and is subject to wear. However, the bearing elements  120  and  140  are Phenolic type bearings made of a durable, yet low friction machinable material. The bearing  104  may be made from a laminated plastic material that may include dry lubrication compounds. Suitable Phenolic bearing materials are available from ScanPac Mfg., Inc. of Menomonee Falls, Wis. Therefore, the bearing  104  may be removed and the elements  120  and  140  machined if necessary to maintain smooth bearing surfaces. If too much thickness is lost, one or more shims  160  may be inserted against the base  122  and/or the base  142 , as shown in  FIGS. 10 and 11 . The shims  160  are also made of a durable low friction material and maintain an appropriate height for the bearing  104 . Use of shims extends the life of the bearing and provides for reuse of bearing elements rather than a single use and disposal of the bearing elements. 
         [0034]    For some applications, further lubrication may be utilized. As shown in  FIG. 6A , the bearing element  120  may be configured to include one or more lubrication channels  180 ,  182  and  184 . In the configuration shown, a lubrication channel  180  is formed in the outer annular raised portion  130 , a lubrication channel  182  is formed in the inner annular raised portion  128  and a lubrication channel  184  is formed in the base  122 . It can be appreciated that fewer and more channels may be utilized for different bearings and for some applications. Moreover, the lubrication channels may be located and oriented in different configurations to facilitate distribution of lubricants to various places requiring additional lubrication. 
         [0035]    As shown in  FIGS. 12-15 , a second embodiment is shown of a bearing  200  suitable for use with a closed face tong. The bearing element  200 , shown as an upper bearing element in  FIG. 12 , may be reversed for use as a lower bearing element. However, in some applications the upper and lower bearing elements may have a different configuration. The closed face bearing element  200  includes a base  202  forming a center opening  204 . The closed face bearing element  200  includes an outer wall  206  that extends from both ends of a flattened vertically planar portion  208 . The flattened portion  208  provides an opening  210  to receive a gear  118 , as shown in  FIG. 16 . The closed face bearing  200  also includes alignment holes  212  through the base  202 . As with the open face tong bearing  104 , the closed face tong bearing  200  is configured so that the edges of the outer wall  206  meet and form a continuous curving outer wall portion when the upper bearing element and the lower bearing element are set together. 
         [0036]    It may also be appreciated that a machinable bearing may take other similar configurations for use with multiple types of tongs used throughout the industry. Moreover, the shims may also be configured differently to accommodate for the different sizes and applications for the tong bearings. 
         [0037]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.