Abstract:
A torch carriage assembly for use in bevel cutting a pipe has a ring gear which rotates concentrically about the pipe longitudinal axis. A shaft extending perpendicularly from the ring gear carries a torch arm block assembly which positions the cutting torch in relation to the pipe. A bracket is adaptable between a first configuration prohibiting and a second configuration permitting rotation of the shaft about its longitudinal axis for bevel cutting round pipes and out-of-round pipes, respectively. In the second configuration, a guide wheel assembly mounted on the shaft traces the surface of the pipe. A tension assembly continually urges the guide wheel assembly into contact with the surface of the pipe so that the angular position of the torch arm block assembly accurately reflects the out-of-round conditions of the pipe.

Description:
This invention relates generally to torch equipment for bevel cutting pipe and more particularly concerns a ring gear mounted; rack adjustable torch arm carriage assembly capable of accurately bevel cutting out-of-round pipes. 
     Pipe cutting torches are generally mounted on either a wheeled carriage which rides directly on the outer surface of the pipe or on a carriage which rides on a ring gear which surrounds the circumference of the pipe. 
     The wheeled carriage device travels on the pipe. Therefore, out-of-round adjustment is generally unnecessary if it is assumed that the pipe cross section along the path of the wheel carriage is identical to the pipe cross section along the path of the torch. However, adaptation of the wheeled carriage device to a variety of pipe sizes is time consuming and complicated. Furthermore, the tendency of the wheeled carriage device to drift during operation introduces error in the accuracy of the cut. The net result is a comparatively slow and inaccurate cutting operation. 
     The ring gear carriage devices use a saddle fixed to the outer diameter of the pipe with the ring gear being rotatable around the pipe. A specific saddle and ring gear is used for each diameter of pipe and the carriage is removably mounted to the ring gear. Thus, set-up requires only that the user mount the saddle on the pipe and attach the carriage to the ring gear. Since the carriage travels on the ring gear and not on the pipe surface, extremely accurate cutting is possible at a relatively high speed. However, if the pipe is not round, as the carriage travels on the round ring gear, the distance between the torch and the outer surface of the pipe will vary along the out-of-round pipe. As a result, a torch angled to produce a beveled cut will cause the cut to deviate from the anticipated plane of the cut transverse to the pipe. To overcome this deviation, some known ring gear devices raise and lower the torch radially in relation to the pipe. However, raising and lowering the torch in a radial direction still introduces inaccuracy into the cut if the pipe contour which causes the torch to be raised and lowered is not the same as the pipe contour in the path of the torch. Presently known ring gear devices with out-of-round capability therefore provide limited assistance in maintaining cut accuracy. 
     A further problem with known ring gear devices with a mechanism for raising and lowering the torch in response to out-of-round contours is that the mechanism is an integral part of the device. A purchaser who may or may not have a need for out-of-round capability in the future must choose whether to buy the considerably more expensive out-of-round equipment which may never be needed or the device that does not have the out-of-round capability. If it is subsequently necessary to buy the more expensive out-of-round device the other device may be useless. 
     Another problem with known ring gear devices with out-of-round capability is that the structure affording the out-of-round capability complicates the device to the extent that time consuming adjustments are necessary to configure the assembly so as to permit making inverted bevel cuts. 
     It is, therefore, an object of this invention to provide a ring gear mounted rack adjustable torch arm carriage which bevel cuts round pipe accurately. Another object of this invention is to provide a ring gear mounted rack adjustable torch arm carriage which is adaptable to receive a separate assembly affording out-of-round capability. A further object of this invention is to provide a ring gear mounted rack adjustable torch arm carriage which affords out-of-round capability without radially displacing the torch arm. Yet another object of this invention is to provide a ring gear mounted rack adjustable torch arm carriage which affords out-of-round capability by angular motion of the torch about an axis parallel to the pipe axis. It is also an object of this invention to provide a ring gear mounted rack adjustable torch arm carriage which is rack adjustable to vary the distance between the guide assembly and the torch. Still another object of this invention is to provide a ring gear mounted rack adjustable torch arm carriage which is readily adjustable to permit inverted bevel cuts. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a torch carriage assembly is provided for use in bevel cutting a pipe. A ring gear having a diameter greater than the diameter of the pipe is adapted to be mounted on the pipe for concentric rotation about the longitudinal axis of the pipe. A shaft is mounted on the ring gear and extends perpendicularly therefrom. A torch arm block assembly is fixed on the shaft and adapted to position the cutting torch in relation to the pipe so as to travel a desired cutting path on the pipe as the ring gear is rotated about the pipe longitudinal axis. A shaft mounting bracket is adaptable between a first configuration prohibiting rotation of the shaft about its longitudinal axis and a second configuration permitting rotation of the shaft about its longitudinal axis. In the first configuration the device is usable for bevel cutting round pipes and in the second configuration for bevel cutting out-of-round pipes. When in the second configuration for bevel cutting out-of-round pipes, a guide wheel assembly is also used. The guide wheel assembly is adapted to be mounted on the shaft and has a guide wheel which traces the surface of the pipe as the shaft moves concentrically about the longitudinal axis of the pipe. The guide wheel assembly causes rotation of the shaft and therefor rotation of the torch arm block assembly in response to out-of-round conditions on the surface of the pipe. A tension assembly linking the shaft and the ring gear is adapted to continually urge the guide wheel into contact with the surface of the pipe so that the angular position of the torch arm block assembly accurately reflects out-of-round conditions on the surface of the pipe. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
     FIG. 1 is a front elevation view of a preferred embodiment of the ring gear mounted rack adjustable torch arm carriage assembly with out-of-round capability; 
     FIG. 2 is a cross-sectional view taken in vertical plane through the shaft of the carriage assembly of FIG. 1; 
     FIG. 3 is a cross-sectional view taken along the line  3 — 3  of FIG. 1; 
     FIG. 4 is a cross-sectional view taken along the line  4 — 4  of FIG. 1; 
     FIG. 5 is a cross-sectional view taken along the line  5 — 5  of FIG. 1; 
     FIG. 6 is an elevation view with parts broken away of the carriage assembly of FIG. 1 used in conjunction with an out-of-round pipe; and 
     FIG. 7 is an elevation view with parts broken away of the carriage assembly of FIG. 1 used in conjunction with an out-of-round pipe having high and low spots on its outer surface. 
    
    
     While the invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Turning first to FIGS. 1 and 2, a ring gear mounted carriage assembly for bevel cutting a pipe P using a torch T is illustrated. A shaft  11  extends in longitudinal alignment with the pipe P from a bracket  13  which is fixed to the ring gear  15  of a saddle machine (not shown) seated on the pipe P. As the ring gear  15  is rotated about the pipe P, the bracket  13  carries the shaft  11  with the longitudinal axis of the shaft  11  traveling in a circular path defining a cylinder around the longitudinal axis of the pipe P. Given a fixed and accurate circular configuration of a ring gear concentrically disposed about the longitudinal axis of the shaft  11 , if the pipe P is out-of-round along the path of the cut to be made by the torch T, the distance between the end of the torch T and the surface of the pipe P will vary accordingly. As shown in FIG. 1, for a bevel cut at an angle θ, if an out-of-round pipe condition causes variance in the vertical spacing Z between the end of the torch T and the surface of the pipe P, then the path of the cut will deviate inwardly and outwardly in the X direction on the pipe P as the distance Z increases and decreases, respectively. 
     As shown in FIGS. 1 and 2, the shaft  11  supports a guide wheel assembly  30 , a spring tension assembly  50  and a torch arm block assembly  70 . The torch arm block assembly  70  travels on a rack  17  so that the entire torch arm block assembly  70  can be reciprocated in the X direction on the shaft  11 . As best seen in FIG. 2, the shaft  11  is seated in a bore  19  in the bracket  13 . A washer  21  at the end of the shaft  11  and bracket  19  has a seat  23  with a diameter slightly greater than the diameter of the shaft  11 . If the washer  21  is reversed so that the washer face having the seat  23  is against the end of the shaft  11  then, when the screw  25  is inserted through the washer  21  and tightened into the shaft  11 , the shaft  11  will insert into the seat  23  so that the face of the washer  21  can abut the bracket  13 . In this condition, the washer  23  binds the shaft  11  in relation to the bracket  13  and the shaft  11  is unable to rotate about its longitudinal axis. In this condition, the torch arm block assembly  70  can be used without the guide wheel assembly  30  to bevel cut pipes P which are not out-of-round. However, by reversing the washer  23  to the condition shown in FIG. 2, the end of the shaft  11  is not engaged in the seat  23 . Therefore, when the screw  25  is tightened through the washer  23 , the washer  23  is pulled into abutment with the shaft  11  but is not pulled into abutment with the bracket  13 . Therefore, without other provision, the shaft  11  is free to rotate on the bracket  13  on bearings  27  about its longitudinal axis. Another washer  29  on the opposite end of the bracket  13  from the seated washer  23  and abutting a land on the shaft  11  completes this reversible assembly. 
     If out-of-round capability is desired, the user can later purchase the guide wheel assembly  30 , reverse the washer  21  to allow rotation of the shaft  11 , and convert the existing device into an out-of-round device. With the washer  21  in the position shown in FIG. 2, the shaft  11  is free to rotate to accommodate use of the torch arm block assembly  70  in bevel cutting and out-of-round pipe P. Looking at FIG. 3, a guide wheel assembly  30  for permitting rotation of the shaft  11  in response to out-of-round contours in the surface of the pipe P is illustrated. The guide wheel assembly  30  includes an arm  31  which is essentially a length of solid round stock having a chordal flat  33  along almost its entire length. The lower end of the arm  31  has a clevis  35  in which a guide wheel  37  is journaled for rotation. A mounting block  39  is slidably engaged for vertical reciprocation on the rod  33 . The bore through which the arm  31  extends has a corresponding flat engaged with the flat  33  on the arm  31 . This locks the block  39  against rotation about the longitudinal axis of the arm  31 . A wing nut  41  extends into the block  39  to engage with the flat  33  of the arm  31 . Thus, the wing nut  41  serves as a set screw for fixing the elevation of the block  39  in relation to the arm  33 . The block  39  also has a bore extending on an axis transverse to the arm  33  through which the shaft  11  extends. The top of the bore is machined  43  to permit the rack  17  on the shaft  11  to pass through the block  39 . The bottom of the block  39  is also machined  45  so that a lock screw  47  extending into the block  39 , through the machined portion  45  and into the block  39  can be used to clamp the block  39  to the shaft  11 . As shown, the lower end of the arm  31  is forwardly angled so as to permit the torch T, when the structure is complete, to be radially aligned with the longitudinal axis of the pipe P. 
     As best seen in FIG. 1, once the guide wheel assembly  30  is positioned on the shaft  11 , the permanent location of the guide wheel assembly  30  can be set by loosening the lock screw  47 , adjusting the position of the guide wheel assembly  30  in the X direction and tightening the lock screw  47  to fasten the block  39  to the shaft  11 . The wing nut  41  can then be loosened and the position of the arm  31  in the block  39  vertically adjusted so that the guide wheel  37  is in appropriate disposition on the surface of the pipe P. The wing nut  41  can then be tightened to secure the arm  31  in this position. 
     Turning to FIG. 4, the spring tension assembly  50  is illustrated in greater detail. As best seen in FIG. 2, the bracket  13  is fixed to the ring gear  15 , preferably by the use of bolts or screws through holes  51  provided through the bracket  13 . The shaft  11  extends through the bracket  13  and, when engaged with the unseated side of the washer  21 , is free to rotate within the bracket  13 . A spring housing  53  is fastened to the bracket  13 , as shown by use of bolts  55 . A spring  57  coiled about a spring shaft  59  extends from a closed end of the housing  53  through an open end of the housing  53 . The shaft  59  extends to a travel limit  61 . A spring block  63  fixed to the shaft  11  and extending radially from the shaft  11  has a bore through its radial end through which the spring shaft  59  extends to the travel limit  61 . A tension adjustment knob  65  threaded on the spring shaft  59  at the closed end of the housing  53  permits the tension of spring which biases against rotation of the shaft  11  to be adjusted so as to constantly urge the wheel  37  of the guide wheel assembly  30  against the surface of the pipe P throughout the motion of the guide wheel  37  about the circumference of the pipe P. As the guide wheel  37  traces out-of-round conditions, the guide wheel  37  causes the shaft  11  to rotate accordingly. 
     Turning now to FIG. 5, the torch arm block assembly  70  is illustrated in greater detail. The assembly  70  includes a torch arm block  71  having a bore in a lower portion thereof so that the block  71  can be disposed on the shaft  11 . As shown, the block is machined  73  so as to accommodate passage of the rack  17  through the block. The block  71  is also machined  75  to accommodate a pinion  77  rotatable by an adjustment knob  79  and cooperable with the rack  17  to manually reciprocate the block  71  in the X direction on the shaft  11 . The block is also machined  81  so that a lock screw  83  extending through the block  71  across the machined portion  81  and again into the block  71  permits securing the block  71  against movement in the X direction after the block  71  has been positioned by rotation of the knob  79 . The upper part of the block  71  is provided with a pair of parallel bores  85 , one below the other, in which a torch holder  87  can be disposed. A torch holder support  89  is extended through one of the bores, as shown the upper bore  85 , and is locked in place by a nut  91 . In order to maintain proper orientation of the holder  87 , the support  89  is provided with pins (not shown) which engage in apertures (not shown) in the block  71  and are locked in this position by the tightening of the nut  91  on the support  89 . 
     Turning to FIG. 6, the torch T is aligned in substantially a diametric plane in relation to the longitudinal axis of the pipe P with the guide wheel  37  riding on the surface of the pipe P. In response to variations in the contour of the pipe P, rather than restricting motion solely in a radial direction in relation to the horizontal axis of the pipe P, the guide wheel assembly  30  causes the torch arm block assembly  70  to rotate about the shaft  11 . Since the response of the guide wheel assembly  30  to irregularities in the contour of the outer surface of the pipe P is to rotate rather than raise or lower the position of the torch T relative to the surface of the pipe P, variations in Z direction displacement are minimized and therefore cutting inaccuracies in the X direction are also minimized. Moreover, looking at FIG. 1, since the torch T is at the angle θ, to produce a bevel cut, the impact of any radial displacement from the surface of the pipe P is offset to some degree by the concomitant variation in the angle θ which is no longer in a vertical plane. The net result is a more accurate cut than is possible in bevel cutting devices using only radial displacement of the torch T from the pipe P. 
     Looking at FIG. 7, the operation of the guide wheel assembly  30  and resultant positioning of the torch T is illustrated in relation to an exacerbated deformity in the contour of the pipe P, as shown perhaps by a weld W on the outer surface of the pipe P or a depression D in the pipe P on or into which the guide wheel  37  will be raised or depressed in response to the tension in the spring tension assembly  50 . 
     Looking again at FIGS. 1,  6  and  7 , the torch holder  87  may also include a rack and pinion assembly controlled by an adjustment knob  93  to permit the manual variation of the distance between the tip of the torch T and the pipe P. Furthermore, the torch holder  87  may be secured to the torch arm block  71  using a torch arm support  95  which permits angular displacement of the support  89  by operation of a bevel angle ratchet handle  97 . That is, with the ratchet handle  97  in a release position, the torch support  89  can be rotated on the torch arm support  95  to provide the desired angular position of the torch T and the ratchet handle  97  rotated to a locked position to assure that this angle is maintained throughout operation of the device. Typically, the torch T is provided with oxygen and acetylene control valves O and A, respectively, and a main torch valve M for admitting the proper mix of oxygen and acetylene to the torch T. 
     It should be noted that, with the torch arm block assembly  70  being manually reciprocable on the rack  17 , inverted bevel cuts are easily accomplished by transferring the torch arm block  71  to a suitable position on the shaft  11  and using the bevel angle ratchet handle  97  to permit rotation of the torch T from a normal bevel position which is forward of vertical alignment of the torch T to an inverted bevel position which is rearward of vertical alignment of the torch T. 
     Thus, it is apparent that there has been provided, in accordance with the invention, a ring gear mounted rack adjustable torch arm carriage assembly with out-of-round capability that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art and in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit of the appended claims.