Abstract:
The disclosure describes a slitting saw used to cut an opening in a pipe. The saw generally comprises a housing mounted on an XYZ positioning system, a drive assembly and a cutting blade. A motor is used to drive a gear train which creates rotating of the cutting blade. The cutting blade makes a bevel cut into the pipe which allows for a new piece to be welded into the window cut by the present invention.

Description:
BACKGROUND OF THE INVENTION 
   Field of the Invention 
   The present invention relates to a saw for simultaneously cutting and beveling a window into a wall of a pipe or vessel. The saw uses a cutting blade, a drive motor for rotating the cutting blade, and a housing enclosing the unit. 
   Steel pipes, which carry steam and/or water, will over time become worn and thin at points, especially at bends or intersections in the pipe. The old method of replacing worn portions of a pipe consisted of “torch cutting” out the bad section, grinding a bevel cut by hand, and then installing a replacement piece into the window with its bevel edges, welding it into place, and then grinding down the weld to smooth out the surface. This method is labor intensive. A need exists, therefore to provide a machine to replace the worn spots in the pipe, rather than replacing the entire pipe, in a faster and easier manner. The present invention permits one to cut a window into the pipe while simultaneously putting a bevel prep on the opening formed in the pipe as the window is being cut, thus eliminating the preparatory bevel grinding operation previously required. 
   SUMMARY OF THE INVENTION 
   The present invention provides a slitter saw used to cut an opening in a pipe, where the pipe is simultaneously cut and prepped for receiving a replacement part. The saw&#39;s housing is mounted on a xyz positioning system. The user can then position the saw against the pipe at a precise location using the three axis positioning system. Once a blade of the saw is properly positioned against the pipe to be cut a drive assembly is engaged for rotation of a cutting blade. The cutting blade is structured to make beveled incisions into the pipe such that once the cut piece is removed from the pipe a new prepped piece can be inserted in its place and welded into place. A drive motor engages a gear train for rotating a series of shafts, which are operatively coupled to the cutting blade. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing features, object and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. 
       FIG. 1  is a front perspective view of a slitting saw construed in accordance with the present invention, where the slitting saw is mounted on a xyz positioning system; 
       FIG. 2  is a top perspective view of the present invention; 
       FIG. 3  is an exploded view of a the present invention; and 
       FIG. 4  is a cross sectional view of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows the claimed slitting saw assembly mounted on a xyz positioning system. The slitting saw assembly is generally indicated by the numeral  10  and the xyz positioning system is generally indicated by the number  12 . 
     FIG. 2  is a perspective view of the housing which encloses the drive assembly. A bottom cover plate  14  is provided as support for the shafts used in a gear train of the drive assembly to be described below. As seen in  FIG. 3 , two generally annular recesses  16  and  18  are provided in the plate  14  to provide clearance for the rotation of the shafts  20  and  22  in the gear train. The drive shaft  20  rests in recess  16  and idler shaft  22  rests in recess  18 . A generally circular aperture  24  is cut through the base cover plate  14  allowing a cutter shaft  26  to pass through the cover plate  14 . An elastomeric single lip seal  28  surrounds an annular stop  27  in the center portion of the cutter shaft  26  to prevent ingress of metal particles into the housing assembly. A gearbox case  30  is mounted to the bottom cover plate  14  by bolts (not shown). A series of generally circular and interconnected apertures  32 ,  33 , and  35  are provided in the gearbox case to accommodate the aforementioned gear train. The drive shaft  20 , idler shaft  22 , and cutter shaft  26  each extend through the interconnected circular apertures  32 ,  33 , and  35 . The generally circular interconnected apertures  32 ,  33 , and  35  are sized to accommodate the various gears  80 ,  90 ,  92 , and  102  in the gear train. 
   A single horizontal side aperture  34  is provided in the gearbox case  30  for receiving a first bevel gear  36  where the first bevel gear  36  penetrates the single horizontal aperture  34  and a semi-circular recess  38  is provided for accommodating of the first bevel gear  36  within the gearbox case  30 . 
   The gearbox case  30  has two levels along the vertical length dimension. The shorter level  40  is adjacent to the longer level  42 . A bearing housing  44  rests on and is bolted to the top of the shorter level  40  of the gearbox housing  30 . The bearing housing  44  has two circular apertures  44   a  and  44   b  which accommodate bearings  96  and  84  respectively. A bearing cover  46  is provided to insure that bearings  84  and  96  are not exposed to metal particles generated as a workpiece is being cut. 
   A bevel gear housing  48  surrounds the second bevel gear  50  and is bolted to the top level  42  of the gearbox housing  30 . A bevel gear cover  52  is affixed with screws to the top of the bevel gear housing  48  and a top cover plate  54  is likewise secured to the top of the bevel gear housing  48 . 
   As shown in  FIGS. 1 and 4 , a cutting blade  56  is disposed at the bottom of the slitting saw  10  adjacent the bottom plate  14 . The cutting blade  56  has seven-blade surface on its perimeter and a bevel blade surface  57 , as best seen in  FIG. 4 . The cutter shaft  26  protrudes through the circular aperture  24  of the bottom cover plate  14 . The bottom of the cutter shaft  26  is then inserted through a blade collar  58 . A cutting blade  56  is operatively coupled to the cutter shaft  26  such that rotation of the cutter shaft results in rotation of the cutting blade  56 . The cutting blade  56  is secured to the cutter shaft  26  first by inserting a pair of dowels  60  through the base of the cutting blade  56  and into two corresponding apertures  62  in the blade collar  58 , and a locknut  62  screws onto the threaded ends  64  of the cutter shaft  26 . 
   Rotation of the cutting blade  56  is affected by the gear train. Specifically, the first bevel gear  36  journaled for rotation in the horizontal side aperture  34  of the gearbox housing  30  by means of ball bearings  37  that set in aperture  34 . The teeth of the first bevel gear  36  mesh with the teeth of the second bevel gear  50 . The second bevel gear  50  is operatively keyed to the drive shaft  20  such that rotation of the first bevel gear  36  translates to rotation of the drive shaft  20 . The drive shaft is journaled for rotation in the housing by a first and second bearing  68  and  70  that are mounted proximate to the opposite ends of the drive shaft  20 . The first bearing  68  is generally positioned at the lower end of the drive shaft  20  near the base plate  14  when viewed as in  FIG. 3 . The second bearing  70  is positioned on the drive shaft  20  between the second bevel gear  50  and a threaded end  66  of the drive shaft. The second bearing  70  is preferably a TIMKEN bearing that is held on the drive shaft by a lock washer  72  and a threaded nut  74 . A first helical gear  80  is operatively keyed to the drive shaft  20  as well. 
   The idler shaft  22  is disposed parallel to the drive shaft  20  in the gear housing  30 . The idler shaft  22  is journaled for rotation by a third and fourth bearing  82  and  84  where the third bearing  82  is mounted at the base of the idler shaft  22  near the base plate  14 . Bearings  82  and  84  are, again, preferably TIMKIN bearings that can be periodically adjusted as they wear. The fourth bearing  84  is mounted near the top of the idler shaft  22  and fixed to the shaft by a washer  86  and threaded nut  88 . A second helical gear  90  is operatively locked to the idler shaft  22  by a key member (not shown). The second helical gear  90  meshes with the first helical gear  80 . A third helical gear  92  is also mounted on idler shaft  22  in between the second helical gear  90  and the fourth bearing  84 . The third helical gear  92  is operatively keyed to the idler shaft  22  for rotation therewith. 
   The bottom portion of the cutter shaft  26  passes through the bottom aperture  24  of the base plate  14 . The cutter shaft  26  is journaled for rotation in the bottom aperture  24  by a fifth bearing  94  that sits in the aperture  24  and a sixth bearing  96 . The fifth bearing  94  is mounted directly on top of the annular stop  27  and the sixth bearing  96  is seated in the aperture  44   a  such that the top portion of the cutter shaft  26  is supported thereby. A lock washer  98  and threaded nut  100  secures the shaft  26  in place. Operatively keyed to the cutter shaft  26  is a fourth helical gear  102  which is located between the fifth bearing  94  and the sixth bearing  96  on the cutter shaft  26 . The fourth helical gear  102  meshes with the third helical gear  92  to transfer motion from the idler shaft  22  to the cutter shaft  26 . 
   A speed reducing gear train is now formed in the slitting saw  10 . A motor which may be electric, pneumatic or hydraulic is adapted to be connected to rotate the first bevel gear  36  which engages the teeth of the second bevel gear  50  rotating the second bevel gear. Since the second bevel gear  50  is operatively keyed to the drive shaft  20  the bevel gears transfer rotation to the drive shaft  20 . Rotation of the drive shaft  20  results in rotation of the first helical gear  80  which is engaged with the second helical gear  90  causing rotation of the idler shaft  22 . The third helical gear  92  is also operatively keyed to the idler shaft  22  such that the rotation of the idler shaft  22  causes rotation of the third helical drive gear  92 . Because the third helical gear  92  meshes with the fourth helical gear  102 , rotation of the idler shaft is transferred to the cutter shaft  26 . Rotation of the cutter shaft  26  results in rotation of the cutting blade  56 . 
   To insure that the relevant gears mesh properly a first spacer  104  is mounted on the drive shaft  20  between the first bearing  68  and the first helical gear  80 . A second spacer  106  is mounted on the drive shaft  20  between the second bevel gear  50  and the second bearing  70 . A third spacer  108  is mounted between the top of the third helical drive gear  92  and the fourth bearing  84  so that the fourth bearing is property aligned. A fourth spacer  110  is placed between the top of the fourth helical gear  102  and the sixth bearing  96  so as to align the sixth bearing  96  and the fourth bearing  84 . 
   The saw blade  56  is divided into a sever blade  57   a  and a bevel blade  57   b . The sever blade  57   a  makes an initial incision into the pipe and the bevel blade  57   b  bevels the edge of the incision. The XYZ positioner  12  allows the length and depth dimensions to be set so that two parallel vertical cuts can be made on the pipe. The workpiece is then repositioned to make two parallel horizontal cuts on the pipe. The cuts intersect so that a window is cut into the side of the pipe. Once the window is cut into the pipe, it can be filled with a similarly shaped plug cut from a tubular member of the same diameter as the pipe. The plug cut can be made from the slitter saw as well. The plug is welded into the window with the bevel edges of the plug mating with the beveled edges of the window. 
   This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.