Abstract:
In an improvement to a pipe re-facing machine having a rotatable flange plate and a coaxially-mounted collar rotatable with and longitudinally movable relative to the flange plate, a support bracket projects from the flange plate, and a support block is retainingly mounted to and movable relative to the support bracket in an angled radial direction. The support block is adapted to receive a tool holder carrying a cutting element. An actuating mechanism is engageable with the support block such that longitudinal movement of the collar will move the support block relative to the support bracket. The actuating mechanism can thus move the cutting element in an angled direction relative to the axis of a tubular workpiece, thereby enabling machining of a bevelled edge on an annular shoulder of a tubular workpiece non-rotatably mounted to the re-facing machine by longitudinally moving the collar while rotating the flange plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit, pursuant to 35 U.S.C. 119(e), of U.S. Provisional Application No. 61/434,232, filed on Jan. 19, 2011, and said provisional application is incorporated herein by reference in its entirety for continuity of disclosure. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates in general to apparatus for re-facing the seal faces of tubular workpieces such as drill pipe and drill collars, and in particular to apparatus for bevelling the perimeter edges of the seal faces of such workpieces. 
       BACKGROUND 
       [0003]    Oil wells and gas wells are typically drilled into the ground by rotating a “drill string” made up of multiple sections (or “joints”) of drill pipe connected end-to-end by means of threaded joints, with a suitable drill bit attached to the bottom of the drill string. The drill string typically incorporates heavier tubular members known as heavyweight pipe or drill collars, positioned between the drill bit and the assembly of pipe sections, in order to increase the vertical load on the drill bit and thus enhance its operational effectiveness. Drilling fluid (or “mud” as it is commonly referred to in the industry) is circulated under pressure downward through the drill string and out through ports in the drill bit, and upward to the surface via the annulus between the drill string and the wellbore. 
         [0004]    A typical drill collar is fabricated with a “pin end” having a tapered external (i.e., male) thread, and a “box end” having a tapered internal (i.e., female) thread for mating engagement with the pin end of another drill pipe section or drill collar. As well, each pin end of the drill collar is formed with an annular shoulder adjacent the base of the male thread, and the outer face of each box end of the drill collar is formed with a corresponding annular shoulder. When a drill collar connection is “made up” by threading the pin end of one collar into the box end of another collar, the annular shoulders of the pin end and box end are brought into compressive metal-to-metal contact so as to create a mechanical seal preventing leakage of drilling mud. Because of this important function, the annular shoulders of the pin and box ends of the drill collars may alternatively be referred to as “seal shoulders” or “torque shoulders”, and the contact surface of a torque shoulder may be referred to as a “seal face”. 
         [0005]    In order for torque shoulders to serve their sealing function as effectively as possible, the seal faces should ideally be uniformly planar and precisely perpendicular to the longitudinal axis of the drill string, and the seal faces should ideally be very smooth, and free from even minor damage or defects. 
         [0006]    It is also customary and highly preferred to chamfer or bevel the outer circumferential edges of the seal faces (typically at an angle of approximately 45 degrees), primarily to protect the seal faces from damage during shipping and handling of the drill collars as well as from impact damage that could otherwise occur in the outer regions of the seal faces after a drill collar assembly has been made up and put into service. Although the angled faces of the bevelled edges do not come into contact with other components and do not have a direct sealing function, these angled faces as well should ideally be smooth and free from defects, for reasons discussed later in this document. 
         [0007]    Unfortunately, the seal faces and bevelled edges of drill collars and other oilfield tubular items are commonly damaged due to rough handling, accidental impacts, and other incidents of typical well-drilling operations and the sometimes harsh environments in which these operations are conducted. Even minor damage to a seal face, such as scratches and nicks, can significantly impair the effectiveness of the mechanical seal between mating seal faces, to the point where there is no practical option except to replace the damaged tubular and, if possible, to re-face the damaged tubular to restore the stringent seal face requirements discussed above (to facilitate or enable later re-use in the field). Because of these stringent requirements, re-facing of torque shoulders must be carried out with great precision, and one way to do so is to ship the damaged tubulars to a machine shop at an off-site location. However, that is not an ideal option due to transportation costs and lost field production time, and/or the need to have an on-site stock of replacement tubulars, ready for installation while the damaged tubulars are being re-faced in the shop. 
         [0008]    A number of machines have been devised for re-facing damaged tubulars in the field, to avoid the cost and inconvenience of shipping them to a machine shop. One particularly good example of such a machine is disclosed in U.S. Pat. No. 4,149,436 (Blattler), which is incorporated herein by reference, and corresponding Canadian Patent No. 1,080,948. The Blattler machine provides a threaded mandrel adapted to receive either the pin end or box end of a tubular workpiece such as a drill collar, the other end of which is supported by a suitable steady rest or other support means. The mandrel and the workpiece are stationary (i.e., non-rotating) during operation of the machine. A cylindrical shaft coaxially disposed around the mandrel rotates a flange plate onto which a tool holder is mounted, with the tool holder being radially movable toward or away from the longitudinal axis of the shaft (and, in turn, toward or away from the workpiece). Biasing means, in the form of a helical spring, is provided to bias the tool holder inward toward the workpiece axis. 
         [0009]    The Blattler machine incorporates a wedge mechanism that engages the tool holder such that longitudinal movement of the wedge relative to the cylindrical shaft and toward the tool holder has the effect of displacing the tool holder radially away from the workpiece axis. As may be best seen in FIG. 2 in U.S. Pat. No. 4,149,436, the Blattler machine includes a collar assembly ( 85 ) which coaxially surrounds and rotates with a hollow shaft ( 48 ), which in turn is coaxially disposed around a non-rotating adapter ( 14 ) to which a tubular workpiece may be mounted. The collar ( 85 ) is axially slidable relative to the adapter and the rotary tool head ( 60 ), which is not axially movable relative to the adapter. A first wedge mechanism component (“wedging member  95 ”) is mounted in association with the sliding collar ( 85 ), and a second wedge mechanism component (“actuating arm  84 ”) is mounted to a tool holder ( 62 ), which in turn is mounted to the rotary tool head ( 60 ) so as to be radially movable relative thereto. The actuating arm ( 84 ) extends over and engages a sloping surface of the wedging member ( 95 ) such that axial movement of the collar ( 85 ) toward the rotary tool head ( 60 ) will cause radially outward movement of the actuating arm ( 84 ) and, in turn, the tool holder ( 62 ), and vice versa. 
         [0010]    This apparatus is typically set up in an initial position such that a cutting tool mounted to the tool holder is positioned radially clear of the workpiece but longitudinally positioned to cut a desired depth into the torque shoulder of the mounted end of the workpiece. The cylindrical shaft is then rotated, thus also rotating the faceplate and the tool holder about the non-rotating workpiece. The wedge mechanism can then be gradually withdrawn longitudinally away from the workpiece, such that the rotating cutting tool progresses radially inward and machines a new seal face, removing any previously existing damage or defects. 
         [0011]    In order to re-face the bevelled edge of the torque shoulder, a separate tool holder is mounted to the flange plate of the machine, with a bevelling tool having a cutting edge oriented to match the desired bevel angle. The radial position of this separate tool holder is pre-set and does not change during re-facing of the torque shoulder edge. With the seal face re-facing tool positioned away from the workpiece (by suitable manipulation of the previously-discussed wedge mechanism), and with the bevelling tool radially positioned for alignment with the torque shoulder edge, the rotating cylindrical shaft is moved longitudinally, over the stationary mandrel, toward the workpiece, such that the bevelling tool engages and re-faces the bevelled edge of the torque shoulder. 
         [0012]    In accordance with the operational principles described above, the Blattler machine re-faces the face of the torque shoulder by moving the corresponding cutting tool across and parallel to the seal face, which facilitates the production of a suitably smooth machined surface. However, re-facing of the bevelled edge of the torque shoulder is accomplished by what may be referred to as a plunge cut, meaning that the cutting tool is plunged or forced against and into the workpiece. This process is not conducive to production of an optimally smooth machined bevel surface. Using this process, the cutting tool is susceptible to intermittently catching or bouncing on the workpiece surface due to factors such as mandrel flex or “backlash” resulting from an excessive plunge rate. This can cause what is commonly referred to in machining parlance as “chatter”, which in turn causes the cutting tool to create gouges or other defects in the bevel surface. Such defects in the bevel surface are highly undesirable, particularly because if they occur near the inner perimeter of the bevel surface they can also create unacceptable defects in the seal face. In that event, re-facing of the seal face may have to be repeated. 
         [0013]    It is clearly desirable, therefore, to re-face the bevel edges of torque shoulders using means that do not involve “plunging” motion of the cutting tool, in order to avoid chatter and resultant workpiece damage. Ideally, this operation would be carried out by moving a cutting tool across and parallel to the bevel face, in a manner analogous to the re-facing of torque shoulders as accomplished using the Blattler machine. Unfortunately, the Blattler machine as disclosed in U.S. Pat. No. 4,149,436 cannot carry out this mode of operation, and it is apparent that there are no other known machines or apparatus that are capable of re-facing the bevel edge of a torque shoulder in this desirable fashion. 
         [0014]    Accordingly, there is a need for methods and apparatus for machining or re-facing a circumferential bevel edge on the end of a tubular member using a cutting tool that moves across and parallel to the face of the bevel. There is a further need for apparatus that is capable of carrying out such a bevel re-facing operation and is also adaptable for retrofitting onto re-facing machines that provide for only radial movement of the cutting tool relative to a tubular workpiece. 
       BRIEF SUMMARY 
       [0015]    The present disclosure teaches embodiments of an improvement in a pipe-refacing machine of the general type having:
       a tubular shaft rotatable about a rotational axis;   a flange plate mounted to and rotatable with one end of the tubular shaft and rotatable therewith, with the flange plate having an outer face perpendicular to the rotational axis and also having an opening through which the rotational axis passes;   a stationary and non-rotatable adapter disposed at least partially within the tubular shaft proximal to the opening in the flange plate, for receiving a threaded end of a tubular workpiece such that the longitudinal axis of the workpiece is coincident with the rotational axis; and   a tubular collar coaxially disposed around the tubular shaft so as to be rotatable therewith and movable relative thereto in a direction parallel to the rotational axis.       
 
         [0020]    In broad terms, the improvement comprises:
       a support bracket projecting from the outer face of the flange plate;   a support block adapted to receive a tool holder, with the support block being retainingly mounted to the support bracket so as to be movable relative to the support bracket in an angled radial direction forming an acute angle relative to a radially-outermost portion of the flange plate, and with the acute angle corresponding to the bevel angle of a bevelled edge to be machined or re-faced on an annular shoulder of a tubular workpiece mounted to the adapter; and   actuating means for effecting angled radial movement of the support block relative to the support bracket.       
 
         [0024]    In one embodiment, the support bracket comprises a base plate having a raised section contoured for sliding engagement with a mating recess in the support block. In one variant of this embodiment, the raised section is in the form of a parallelepiped of trapezoidal cross-section. 
         [0025]    In another embodiment, the support bracket comprises a contoured rail member oriented parallel to the desired bevel angle to be machined on an annular shoulder of a tubular workpiece, and the support block comprises a runner block contoured for retainingly mating engagement with the rail member so as to be movable along the rail member. 
         [0026]    In one variant, the actuating means comprises an actuator arm operatively engageable with the support block, with the actuator arm being connected to a slide bracket extending through and radially movable within a radial slot through the flange plate. The slide bracket has a first wedge component operatively engageable with a second wedge component associated with the tubular collar, such that longitudinal movement of the tubular collar (i.e., parallel to the rotational axis) will cause the second wedge component to urge the first wedge component and the slide bracket in a radial direction, thereby causing the actuator arm to move the support block relative to the support bracket. The actuator arm may be formed with an angled outer section disposed between a pair of guide rollers associated with the support block, such that actuator arm remains effective to move the support block in either direction while the angled outer section is movable between the guide rollers transverse to the direction of travel of the support block, to accommodate the angled (or bi-directional) movement of the support block in response to uni-directional (i.e., longitudinal) movement of the tubular collar. 
         [0027]    In another variant, the actuating means comprises a rigid actuator bar extending through a radial slot in the flange plate, with the one end of the actuator bar being swivellingly mounted to the support block and the other end of the actuator bar being swivellingly mounted to the tubular collar, such that longitudinal movement of the tubular collar will cause the actuator bar to move the support block relative to the support bracket. The swivelling connections of the actuator bar accommodate angled movement of the support block in response to longitudinal movement of the tubular collar. 
         [0028]    Optionally, biasing means may be provided to bias the support block in an angled radial direction away from the rotational axis (i.e., such that the a cutting tool mounted to a tool holder mounted to the support block will be biased away from a workpiece mounted to the adapter). By way of non-limiting example, the biasing means may comprise a helical spring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Embodiments will now be described with reference to the accompanying figures, in which numerical references denote like parts, and in which: 
           [0030]      FIG. 1  is a schematic side view of a tubular workpiece mounted to a prior art re-facing machine, with a first embodiment of a bevelling apparatus in accordance with the present disclosure mounted in association with the flange plate of the re-facing machine. 
           [0031]      FIG. 2  is an oblique view of the bevelling apparatus illustrated in  FIG. 1 . 
           [0032]      FIG. 3  is an exploded isometric view of selected components of the bevelling apparatus of  FIG. 1 . 
           [0033]      FIG. 4  illustrates the bracket assembly of the bevelling apparatus. 
           [0034]      FIG. 5  illustrates the sliding tool-support block of the bevelling apparatus. 
           [0035]      FIG. 5A  illustrates one alternative form of the inner lug member shown in  FIG. 5 . 
           [0036]      FIG. 6  illustrates the tool slide actuator of the bevelling apparatus. 
           [0037]      FIG. 7A  is a side elevation of a prior art re-facing machine, shown with bevelling apparatus in accordance with the present disclosure mounted to the flange plate of the machine, and with a tubular workpiece in position for mounting to the mandrel of the re-facing machine. 
           [0038]      FIG. 7B  is an end view of the assembly shown in  FIG. 7A . 
           [0039]      FIG. 8A  is a more detailed end view of the flange plate of a re-facing machine having radial slots for receiving both a seal face cutter and a bevel cutter. 
           [0040]      FIG. 8B  is a schematic side view of a tubular workpiece mounted to a re-facing machine having a flange plate as in  FIG. 8A , with both a seal face cutter and a bevel cutter mounted to the flange plate. 
           [0041]      FIG. 9  is schematic side view of a second embodiment of a bevelling apparatus in accordance with a second embodiment of the present disclosure. 
           [0042]      FIG. 9A  illustrates various components of the alternative actuation mechanism of the embodiment illustrated in  FIG. 9 . 
           [0043]      FIG. 9B  is an exploded isometric view of selected components similar to  FIG. 3 , illustrating modifications for purposes of the alternative actuation mechanism as in  FIG. 9 . 
           [0044]      FIG. 10  is perspective view of a third embodiment of a bevelling apparatus in accordance with the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0045]    As generally depicted in  FIG. 1 , a first embodiment of a bevelling apparatus in accordance with the present disclosure (and indicated in  FIG. 1  by reference numeral  10 ) is mounted to the rotatable flange plate  62  of a re-facing machine  60 , such that bevelling apparatus  10  is movable radially relative to the rotational axis A of re-facing machine  60 . Re-facing machine  60  has a non-rotating mandrel  64  having a longitudinal axis coincident with axis A and adapted to coaxially engage a tubular workpiece  70  and to hold it stationary (i.e., non-rotating) while flange plate  62  rotates. The configuration of the workpiece-engaging end of mandrel  64  depends on the workpiece  70 ; for example, mandrel  64  would have tapered male threading to engage the box end of a drill collar (as in  FIG. 1 ) or, alternatively, tapered female threading to engage the pin end of a drill collar. 
         [0046]    As may be understood from  FIGS. 1 and 8A  in particular, a radial movement mechanism  65  is radially movable within a radial slot  63 A or  63 B in flange plate  62  of re-facing machine  60 . Radial movement mechanism  65  (which does not form part of the broadest embodiments of the bevelling apparatus) may comprise a wedge mechanism as in U.S. Pat. No. 4,149,436, or any other suitable mechanism capable of providing controllable radial movement relative to re-facing machine  60 . As will be explained in greater detail below, bevelling apparatus  10  is coupled to radial movement mechanism  65 , on the workpiece side of flange plate  62 , such that actuation of radial movement mechanism  65  will produce corresponding radial movement of bevelling apparatus  10 . 
         [0047]    In the embodiment more particularly illustrated in  FIGS. 2 through 6 , bevelling apparatus  10  includes a mounting bracket comprising a bracket assembly  20  with a pair of side plates  12  rigidly connected (such as by welding) to opposing side edges  21 A and  21 B of bracket assembly  20  as shown. Bracket assembly  20  has an outer end  20 A and an inner end  20 B. Bracket assembly  20  comprises a base plate  22  plus a raised section  24  in the general form of a parallelepiped having a trapezoidal cross-section, with the wider portion of raised section  24  being disposed above and parallel to upper surface  22 U of base plate  22 . The trapezoidal configuration of raised section  24  is a matter of design preference, and is not essential; in alternative embodiments, raised section  24  could have a different cross-sectional configuration without departing from the scope of the present disclosure. 
         [0048]    Raised section  24  extends approximately between outer end  20 A and inner end  20 B of bracket assembly  20 . Base plate  22  has an elongate slot  23  adjacent and parallel to one side of raised section  24 . On the other side of raised section  24 , proximal to outer end  20 A of bracket assembly  20 , base plate  22  has an outer lug member  26  projecting above upper surface  22 U, with a typically unthreaded bore  26 A. Bracket assembly  20  is suitably adapted for secure mounting to flange plate  62  of re-facing machine  60 . 
         [0049]    Bevelling apparatus  10  further includes a sliding block  30  having an outer end  30 A and an inner end  30 B, upper face  30 U, lower face  30 L, and side edges  31 A and  31 B. Formed in lower face  30 L of sliding block  30 , and extending between outer and inner ends  30 A and  30 B thereof, is a trapezoidal channel  36  configured for a close-tolerance sliding fit with raised section  24  of bracket assembly  20 . Formed in upper face  30 U of sliding block  30 , and extending between outer and inner ends  30 A and  30 B thereof, is a two-section keyway  37  comprising a lower section  37 L and a narrower upper section  37 U. As may be best understood from  FIG. 3 , keyway  37  is configured to receive a tool holder  40  of known type, having an upper section  41  slidably disposable within upper section  37 U of keyway  37 , and a lower section  43  slidably disposable within lower section  37 L of keyway  37 . Tool holder  40  will typically be provided with one or more set screws  42  or other means for releasably fixing the longitudinal position of tool holder  40  relative to sliding block  30 . A bevelling tool  42  with cutting element  44  may be mounted to tool holder  40  as seen in  FIG. 1  (tool holder  40  not being visible in  FIG. 1 ). 
         [0050]    The width of sliding block  30  is such that it cannot impinge upon outer lug member  26  of bracket assembly  20 , and such that its side edge  31 B will at all times be clear of elongate slot  23  in base plate  24  (or at least will not overlap slot  23  so as to interfere with the operation of bevelling apparatus  10 ). 
         [0051]    An inner lug member  32  having a threaded bore  32 A is rigidly connected to inner end  30 B of sliding block  30 , such that the portion of inner lug member  32  in which threaded bore  32 A is formed projects beyond side edge  31 A of sliding block  30 . When sliding block  30  is slidably engaged with raised portion  24  of bracket assembly  20  as previously described, threaded bore  32 A of inner lug member  32  will be aligned with unthreaded bore  26 A of outer lug member  26  of bracket assembly  20 . As shown in  FIG. 2 , a helical spring  82  is positioned between inner lug member  32  and outer lug member  26 , and then an adjustment bolt  80  (having drive head  84 ) is inserted through unthreaded bore  26 A of outer lug member  26  and helical spring  82 , whereupon the threaded end of bolt  80  engages threaded bore  32 A of inner lug member  32 . It may be readily understood, therefore, that the static longitudinal position of sliding block  30  relative to bracket assembly  20  can be adjusted by rotating drive head  84  as required. However, sliding block  30  will remain slidingly movable relative to bracket assembly  20  by a longitudinal force applied to sliding block  30  in the direction toward outer end  20 A of bracket assembly  20 , with helical spring  82  serving as a biasing means which will return sliding block  30  back toward its static position upon relaxation of the longitudinal force. 
         [0052]    Inner lug member  32  may be connected to sliding block  30  by any suitable means such as welding or, alternatively, by means of one or more bolts  33  (or machine screws), for purposes of which inner lug member  32  may be provided with one or more bolt holes  32 B as shown in  FIG. 5A . Alternatively, inner lug member  32  may be formed integrally with sliding block  30 . 
         [0053]    As shown in  FIGS. 1 ,  2 , and  3 , an outer roller  35 A and an inner roller  35 B are mounted to and extend laterally from side edge  30 B of sliding block  30 . Rollers  35 A and  35 B are spaced apart in the longitudinal direction, with the clear spacing between rollers  35 A and  35 B being set to suit the width of the actuator arm  54  of a tool slide bracket  50 , as may be seen in  FIGS. 1 and 6 . Tool slide bracket  50  comprises a base member  52  adapted (such as by means of mounting holes  52 A) for mounting to radial movement mechanism  65 . Actuator arm  54  has an inner section  54 A connected (such as by welding) to and projecting outward from base member  52 , plus an outer section  54 B which is angled, relative to base member  52 , as appropriate to bevel a tubular workpiece  70  at a desired angle. 
         [0054]    As may be seen in  FIG. 1 , when bevelling apparatus  10  is mounted in association with the flange plate  62  of a re-facing machine  60 , with base member  52  of tool slide bracket  50  directly connected to radial movement mechanism  65 , angled outer section  54 B of actuator arm  54  is disposed (preferably with only nominal clearance) between rollers  35 . When radial movement mechanism  65  is actuated, so as to move tool slide bracket  50  radially inward in the plane of flange plate  62 , outer section  54 B of actuator arm  54 , due to its angular orientation, will bear against inner roller  35 B, having the effect of applying a longitudinal force urging sliding block  30  toward outer end  20 A of bracket assembly  20 . As may be seen from  FIG. 1 , this will cause sliding block  30 , and bevelling tool  42  in turn, to move both radially inward and at an acute angle relative to rotational axis A—more specifically, at an angle corresponding to the desired angle for the bevelled face to be machined on the end of workpiece  70 . As sliding block  30  continues its inward movement, outer section  54 B of actuator arm  54  will necessarily move between rollers  35 A and  35 B in the direction transverse to and toward base plate  22  of bracket assembly  20 . It is for this reason that elongate slot  23  is provided in base plate  22 , so that the free end of outer section  54 B of actuator arm  54  can freely pass both transversely through and longitudinally along slot  23 . 
         [0055]    The operation and use of bevelling apparatus  10  may now be readily understood having regard to the preceding description. With a tubular workpiece  70  mounted to mandrel  64  as shown in  FIG. 1  and longitudinally positioned as desired, the initial or static position of sliding block  30 , and in turn the position of bevelling tool  42  relative to the end of workpiece  70 , can be set as desired by appropriate rotation of adjustment bolt  80 . Re-facing machine  60  can then be actuated so as to rotate flange plate  60  and bevelling apparatus  10 . Actuation of radial movement mechanism  65  will then cause bevelling tool  42  to move toward workpiece  70  in a direction parallel to the desired bevel face plane. As bevelling tool  42  thus rotates around workpiece  70  and concurrently moves angularly inward, cutting element  44  will engage workpiece  70  and machine the desired bevelled shoulder edge. 
         [0056]    As schematically illustrated in  FIG. 8B , bevelling apparatus in accordance with the present disclosure makes it possible to re-face the bevelled shoulder of a tubular workpiece  70  concurrently with re-facing of the seal face, using the same basic re-facing machine. This is possible because both operations are carried out without having to move or reposition workpiece  70  longitudinally relative to the re-facing machine. This provides a decided advantage over prior art methods and apparatus which require seal faces and bevelled shoulders to be re-faced in separate and sequential operations. 
         [0057]      FIG. 9  illustrates a second embodiment of the beveller that uses an alternative mechanism for effecting radial movement of a modified sliding block  30 ′ and bevelling tool  42  relative to re-facing machine  60 , instead of the wedge mechanism used in the prior art Blattner machine (per U.S. Pat. No. 4,149,436). Except as described herein and illustrated in  FIGS. 9 ,  9 A, and  9 B, the details of the components of this alternative embodiment correspond to those in the previously described and illustrated embodiment. 
         [0058]    The alternative embodiment of  FIG. 9  includes a bracket  94  (illustrated in detail in  FIG. 9A ) which has a first flange  95  and a second flange  96 . First flange  95  has a hole  95 A for receiving a swivel pin. Second flange  96  extends through elongate slot  23  in base plate  22  and is securely mounted to sliding block  30 ′. As shown in  FIG. 9B , sliding block  30 ′ differs from sliding block  30  in  FIG. 3  in that it does not include any rollers  35 . In the illustrated alternative embodiment, the mounting of second flange  96  to sliding block  30 ′ is accomplished by means of bolts or machine screws (not shown) through holes  96 A in second flange  96  and into threaded holes  39  in one side of sliding block  30 ′. However, alternative means for securely mounting second flange  96  to sliding block  30 ′ may be used instead of bolts or machine screws without departing from the scope of the present disclosure. Although bracket  94  is shown in  FIG. 9A  as being of generally Z-shaped configuration, this is by way of example only; bracket  94  could be of any functionally suitable shape and configuration, 
         [0059]    Referring to  FIG. 9 , re-facing machine  60  includes a collar assembly  61  (similar to collar ( 85 ) in U.S. Pat. No. 4,149,436) surrounding and rotating with a hollow shaft (not shown, but corresponding to hollow shaft ( 48 ) in U.S. Pat. No. 4,149,436), which in turn is disposed coaxially around non-rotating mandrel  64  (not shown in  FIG. 9 ). Collar  61  is axially movable along the hollow shaft and relative to flange plate  62  of re-facing machine  60 . Referring to  FIG. 9A , a bracket  66  of any suitable configuration, with a hole  66 A for receiving a swivel pin, is mounted to collar  61 . A rigid bar  90  (of straight or other suitable configuration) has first and second ends  92  and  93 , with associated holes  92 A and  93 A for receiving swivel pins. 
         [0060]    Referring again to  FIG. 9 , rigid bar  90  is disposed through a radial slot  67  in flange plate  62 , with first end  92  swivellingly mounted to bracket  66  by means of a swivel pin extending through holes  66 A and  92 A, and with second end  93  swivellingly mounted to first flange  95  of Z-shaped bracket  94  by means of a swivel pin extending through holes  93 A and  95 A. Accordingly, axial movement of collar  61  moved away from flange plate  62  will cause rigid bar  90  to pull sliding block  30 ′ along raised section  24  of bracket assembly  20  toward flange plate  62 , in an angular direction corresponding to the desired angle of bevel to be formed on a tubular workpiece  70  by bevelling tool  42  mounted to sliding block  30 ′. Therefore, angled movement of bevelling tool  42  relative to the end of a mounted workpiece  70  is effected by axial movement of collar  61 , but the operative mechanism is the swivelling linkage provided by rigid bar  90  rather than a wedging mechanism. 
         [0061]      FIG. 10  illustrates a third embodiment of a bevelling apparatus in accordance with the present disclosure. In this embodiment, a bevelling tool  42  with cutting element  44  is carried by a tool holder  40  (not shown in  FIG. 10 ) which is received a keyway  137  in a sliding block  130  (which is generally similar to sliding block  30  and sliding block  30 ′ in the other illustrated embodiments). As shown in  FIG. 10 , sliding block  130  is secured to a runner block  122  which is longitudinally movable along a rail member  120 , which in turn is secured to a rail-mounting block  110  secured to the rotatable face plate  62  of a re-facing machine  60 , with the angle of rail member  120  relative to face plate  62  being selected to suit the angle of the bevelled shoulder to be re-faced using the apparatus. 
         [0062]    An adapter block  140  is secured to either or both of runner block  122  and sliding block  130 , and a bracket  142  (functionally analogous to bracket  94  in the embodiment in  FIGS. 9 and 9A ) is secured to adapter block  140 . Movement of runner block  122  along rail member  120  is effected by means of an actuating mechanism essentially the same as the mechanism illustrated in  FIGS. 9 and 9A  and previously described herein. In other words, a rigid bar  90  is disposed through a radial slot  67  in face plate  62 , with rigid bar  90  having a first end  92  (not shown in  FIG. 10 ) swivellingly mounted to an axially-movable collar  61  associated with re-facing machine  60 , and a second end  93  swivellingly mounted to bracket  142  by means of a swivel pin disposed through hole  93 A in second end  93 . Axial movement of collar  61  away from face plate  62  will cause rigid bar  90  to pull sliding block  130  along rail member  120  toward face plate  62 , in an angular direction corresponding to the desired angle of bevel to be formed or re-faced on a tubular workpiece  70  by bevelling tool  42  mounted to sliding block  30 ′. 
         [0063]    Runner block  122  and rail member  120  may be of any suitably mating configuration such that runner block  122  is retained on rail member  120  as it travels therealong. In the illustrated embodiment, runner block  122  and rail member  120  are shown, respectively, as runner block and ball guide rail components of a ball rail system as manufactured by Bosch Rexroth AG (details of which can be viewed at http://www.boschrexroth.com). However, this is by way of example only, and the embodiment shown  FIG. 10  is not limited to the use of these or any other particular types of runner block and rail member. By way of non-limiting example, variant embodiments could use roller rail system components as manufactured by Bosch Rexroth AG, or could use custom-fabricated runner blocks and rail members. Movement of runner block  122  along rail member  120  could be sliding movement or rolling movement or a combination of sliding and rolling movement. 
         [0064]    It will be readily appreciated by those skilled in the art that various modifications of the illustrated embodiments may be devised without departing from the scope and teaching of the present disclosure, including modifications which may use equivalent structures or materials hereafter conceived or developed. It is to be especially understood that the disclosure is not intended to be limited to any described or illustrated embodiment, and that the substitution of a variant of a claimed element or feature, without any substantial resultant change in the working of the apparatus, will not constitute a departure from the scope of the disclosure. It is to also be appreciated that the different teachings of the embodiments described and discussed herein may be employed separately or in any suitable combination to produce desired results. 
         [0065]    In this patent document, any form of the word “comprise” is to be understood in its non-limiting sense to mean that any item following such word is included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element. Any use of any form of the terms “connect”, “engage”, “couple”, “attach”, “mount”, “secure”, or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the subject elements, and may also include indirect interaction between the elements such as through secondary or intermediary structure. 
         [0066]    Relational terms such as “parallel”, “perpendicular”, “coincident”, “intersecting”, and “equidistant” are not intended to denote or require absolute mathematical or geometrical precision. Accordingly, such terms are to be understood as denoting or requiring substantial precision only (e.g., “substantially parallel”) unless the context clearly requires otherwise. Wherever used in this document, the terms “typical” and “typically” are to be interpreted in the sense of representative of common usage or practice, and are not to be understood as implying essentiality or invariability.