Roller reamer with rotatably positioned bearing block
BACKGROUND OF THE INVENTION 
     The present invention relates to roller reamers, used in connection with earth boring tools such as are used in oil and gas drilling. 
     Roller reamers are typically used in drill strings, behind a drill bit for earth boring and drilling. The reamer has an elongate, generally cylindrical body. The reamer body is provided with a plurality of circumferencially spaced pockets: three or four are typically provided, and in each of the pockets there is provided a roller, which may have teeth on it, the purpose of the roller reamer being to enlarge or maintain the size of the bore hole and to stabilize the position of the drill bit, and therefore its direction. For this reason, the roller reamer is also designated as a stabilizer. 
     The rollers are journalled on shafts, and the shafts, in turn, are supported in bearing blocks which are carried by the reamer body. Typically, slots extend in the reamer body generally axially, above and below the pocket, and the bearing blocks are positioned in the slots. Since the centrifugal forces produced by rotation of the drill string tend to cause the bearing blocks to move radially outwardly, provision is made to prevent such radial outward movement. 
     Wagnon, et al., U.S. Pat. No. 3,627,068, discloses a roller reamer construction of the above described type, in which the slot for the bearing block is undercut, and the bearing block has flanges entering into the undercut portion of the reamer body. The slot is axially elongated, so that the bearing block may be moved away from the pocket, to permit introduction of the shaft and roller into the pocket, after which the bearing block is slid downwardly to telescope over the end of the shaft. A screw is threaded into the reamer body, to prevent movement of the bearing block away from the roller pocket. 
     Blau, et al., U.S. Pat. No. 4,428,626, discloses a reamer or stabilizer construction in which wear pads are provided with outwardly extending flanges which engage in an undercut portion of the stabilizer body, to prevent radial outward movement or &#34;throwing&#34; of them when the drill string is rotated. 
     Kloesel, Jr., et al., U.S. Pat. No. 3,303,900, and Terry, U.S. Pat. No. 4,190,124, disclose down-hole tools in which removable parts are joined by a dove tail connection. 
     Allison, et al., U.S. Pat. No. 4,262,760, provides a construction in which a bearing block is of generally cylindrical configuration, and is positioned in a corresponding cylindrical recess in the reamer body, with the axis of the recess and bearing block extending substantially radially of the reamer body. The bearing block engages the recess with an interference fit, and screws are additionally provided to secure the bearing block in place. Removal of the bearing block is achieved with a special tool, after removal of the screws. 
     Gray, U.S. Pat. No. 3,907,048, provides a stabilizer in which bearing blocks are friction fit into recesses in the stabilizer body, and are then additionally secured by screws or welding. 
     The prior art stabilizers have been difficult to assemble and disassemble, particularly with reference to the bearing blocks. Typically, as is given in some of the foregoing examples, there is a friction or interference fit between the bearing block and a corresponding slot or recess in the reamer or stabilizer body. For placement of the bearing block in position, or for removal of the bearing block from the reamer or stabilizer body, there is typically required the application of substantial force, and the utilization of two workmen. Either hammers or hydraulic tools are used to place the bearing blocks in position or remove them, thus requiring additional labor expenses and substantial forces to perform these operations; in some instances, additional equipment such as hydraulic tools are utilized, thereby adding to the expense of the assembly and disassembly of such roller reamers and stabilizers. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a roller reamer having a reamer body provided with one or more pockets, and a roller positioned in each pocket, the roller being carried on a shaft, and the shaft supported by bearing blocks mounted in the reamer body. The reamer body is provided with a recess at the end of the pocket, with a relatively narrow entryway communicating the recess and the pocket, the recess having a width transverse of the axial direction greater than the entryway, and being provided with segmental cylindrical walls at the widest part. The bearing block is of conforming shape to the recess, having mating cylindrical walls, and having a length in the direction of the shaft opening therein which is no greater than the width of the entryway. The bearing block is positioned transversely of its normal position, that is, with the shaft opening therein extending approximately normal to its operative position, and in this position is passed through the entryway and into the recess, where it is rotated ninety degrees so that the shaft opening extends substantially axially. Interengaging means, such as flanges on the bearing block and undercuts in the reamer body, prevent outward throwing of the bearing blocks. The walls defining the recess in the reamer body and the bearing block have a clearance fit, which permits ready assembly and disassembly, more particularly the clearance fit permitting free rotational movement of the bearing block in the recess. 
     Among the objects of the present invention are to provide a roller reamer construction in which the parts may be readily assembled and disassembled, and to provide such a roller reamer construction which will prevent movement of the bearing block after assembly; yet another object of the present invention is to provide such a roller reamer in which there is secure attachment of the bearing block to the reamer body. 
     Yet another object of the present invention is to provide a roller reamer which may be assembled or disassembled without requiring large forces, plural workmen, and a further object is the provision of such a roller reamer in which all of the parts, including the shaft, will be held securely in position, but may be readily removed. 
     Other objects in many of the attendant advantages of the present invention will be readily understood from the following specification, drawings and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevational view of a portion of a roller reamer in accordance with the present invention. 
     FIG. 2 is a cross sectional view, with parts in elevation, taken on the line 2--2 of FIG. 1. 
     FIG. 3 is a cross sectional view taken on the line 3--3 of FIG. 2. 
     FIG. 4 is an exploded perspective view of the shaft, thrust washers and bearing blocks forming a part of the roller reamer as shown in FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, wherein like or corresponding reference numerals are used for like or corresponding parts throughout the several views, there is shown in FIG. 1 a roller reamer generally designated 10 and comprising a generally tubular body 11 having a plurality of rollers 12 of known construction mounted therein. Each roller 12 is supported in a pocket 13. The roller 12 is generally cylindrical, having truncated ends, and the pocket 13 is of generally similar configuration. At each end of the pocket 13 there is provided a recess 14, 16, the pocket 13 communicating with the recesses 14 and 16 through relatively narrow entryways 14a and 16a. 
     Referring to FIG. 2, there may be seen the roller reamer 10 and the body 11, with the roller 12 supported in the pocket 13 on a shaft 17. In each end of the shaft 17, as shown in FIGS. 1 and 4, there is a radial groove 17a, 17b. The shaft 17 extends through a pair of bearing blocks 20, of identical construction. Referring to FIG. 4, each of the bearing blocks 20 may be seen to have a shaft opening 21 extending through it, and having a length L in the direction of the opening 21 which is shorter than the width, transverse to the opening 21. The bearing block 20 is provided at its width with cylindrical surfaces 22 and 23 having as their center an axis A which extends substantially perpendicularly to the axis of the opening 21. Extending from the wall 22 is a flange 24, which also has a cylindrical surface 26 and which is concentric with the axis A. The bearing block 20 is further bounded by a pair of flat surfaces, the surface 27 being shown in FIG. 4, there being a parallel surface 28 not visible in FIG. 4. As is apparent from FIGS. 1 and 4, the width of the bearing block 20, transversely of opening 21 and defined by the cylindrical surfaces 22 and 23, is greater than the length L, defined by the body between the surfaces 27 and 28. 
     Extending into the bearing block 20 from the upper surface 29 thereof are a pair of blind bores 31. 
     The shaft 17 may contain a lubricating system, not shown, for supplying lubrication to the adjacent surfaces of shaft 17 and the roller 12, and to that end may be hollow, with a lubricant discharge slot 18 therein. A pin 19 may extend from the end of the shaft 17, forming part of a lubrication system within shaft 17. Thrust washers 33 are provided on the shaft 17, bearing against the surface 27 of bearing block 20, and having width substantially the same as the width of the surface 27. As shown in FIG. 1, the thrust washers 33 occupy the entryways 14a and 16a communicating the pocket 13 and the recesses 14 and 16. 
     As shown in FIG. 1, the recesses 14 and 16 are of substantially conforming size and shape to the bearing blocks 20. Thus, the recesses 14 and 16 are each provided with segmental cylindrical surfaces 42 and 43 which are in mating engagement with the cylindrical surfaces 22 and 23 of the bearing block 20. 
     Referring to FIG. 3, the three rollers 12 are shown, as are the bearing blocks 20 and the shafts 17. The segmental cylindrical surfaces 42 and 43 of the recess 14 are shown engaged by the segmental cylindrical surfaces 22 and 23 of bearing block 20; the recess 14 is provided with an undercut 44 to receive a flange 24, and is also provided with an undercut 45 to receive a flange 25 which is substantially identical to the flange 24. 
     In FIGS. 1 and 2, to the right of the recess 14 there is a slot 34 having a length slightly greater than the length of the shaft 17. In the slot 34 there may be seen a capscrew 35 threaded into the reamer body 11, with its head in the groove 17b of shaft 17. A second capscrew 36 is provided, to be engaged by shaft 17 should the capscrew 25 break or become loose and fall out of the reamer body 11. The capscrew 35, since it extends into and engages the groove 17b, prevents rotation of shaft 17. Adjacent recess 16, which is identical to the recess 14, there is a slot 37; a capscrew 38 in slot 37, is threaded into the reamer body 11 and engages the radial groove 17a in shaft 17, also to prevent rotation of shaft 17. 
     To assemble the roller reamer 10, a bearing block 20 is positioned in a pocket 13 with the opening 21 extending transversely of the normal position; that is, the bearing block 20 is at right angles to the position shown in FIG. 1. Because the length L of the bearing block 20 along the shaft opening 21 is slightly less than the entryway 16a, the bearing block 20 may be moved to the left as shown in FIG. 1, into the recess 16. It is then rotated on an axis which is a radially extending axis of the reamer body 11, the segmental cylindrical surfaces 22 and 23 matingly engaging the segmental cylindrical surfaces 42 and 43 of the recess 16. Further, the flanges 44 and 45 will enter, respectively, the undercuts 24 and 25. The dimensions and tolerances of the aforementioned parts are such that there is a clearance fit between the recess 16 and its undercuts and the bearing block 20 and its flanges, and as a consequence, the rotary movement will be freely accomplished, by one person, and without resort to heavy hammers or hydraulic tools. A hand tool may be employed, engaging the bearing block 20 through the blind bores 31. The second bearing block 20 is moved through the entryway 14a in the same manner, is then rotated through ninety degrees, and thus occupies the position shown in FIG. 1. The shaft 17 is placed in the slot 34 and the roller 12 and thrust washers 33 are supported in the pocket 13, after which the shaft 17 is moved so that its end with the radial groove 17a passes through the bearing block 20 in the recess 14, a thrust washer 33, the roller 12 in the pocket 13, the other thrust washer 33, the bearing block 20 in the recess 16 and thence into the slot 37. The capscrews 35, 36 and 38 are then threaded into the reamer body 11, thereby completing the assemblage of the one roller 12: the other rollers 12 are equally readily assembled to complete the roller reamer 10. 
     To effect disassembly, the steps are reversed, including the removal of the capscrews 35 and 36, the withdrawal of the shaft 17 first into the slot 34, after which it is removed from the reamer body 11. The roller 12, being free of the shaft 17, is also removed, since it may merely drop out of the pocket 13 along with thrust washers 33. The bearing blocks 20 are then removed by rotating them through ninety degrees and passing them through the entryways 14a and 16a, and then removing them from the pocket 13. Disassembly is relatively easy, since there are no friction or interference fits, all of the fits being clearance fits, or sliding fits in the case of the roller 12 and shaft 17. 
     In operation, the interengagement provided by the flanges and undercuts prevent outward movement of the bearing blocks 20 under the influence of centrifugal forces. Due to the cylindrical, mating relationship between the bearing blocks 20 and the mating recesses 14 and 16, the bearing blocks 20 may not move axially from the recesses 14 and 16. Further, because the shafts 17 extend through the opening 21 in each of the bearing blocks 20, the bearing blocks 20 are prevented from rotating from the position shown in FIG. 1. By this construction, therefore, the entire assemblage of the bearing blocks 20, roller 12 and shaft 17 are securely held in the reamer body 11 during operation, while at the same time assembly and disassembly are readily effected. 
     The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.