Abstract:
A spiral spline groove machine apparatus for manufacturing a sealed spiral spline pipe connection by machining spiral grooves into the bell and spigot end of a length of pipe. A rotating cutter is adapted to cut a spiral groove in the inside of the bell of the pipe or machine the recessed external groove on the male end of the pipe. The cutter is adapted to float on the surface contour of the pipe to allow for variations in the wall thickness of the pipe and provide a consistent depth for the cut in the wall of the pipe without regard to the symmetry of the circular cross section of the pipe. An exit port machining device is also disclose to cut an exit port connected to the inside spiral groove on the bell end of the pipe. Another unique aspect of the invention is the use of a rotational to linear converter using a lead screw to move an entire rotating assembly having the motor output fixed directly to the cutter without an expansion joint.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application hereby claims priority to and is a continuation-in-part of application Ser. No. 10/454,339, filed Jun. 4, 2003 now abandoned which claims priority to and is a continuation-in-part of U.S. provisional application Ser. No. 60/431,511, filed on Dec. 6, 2002, which are hereby incorporated by reference. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   REFERENCE TO A MICROFICHE APPENDIX 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the field of machines for forming pipe joints in general. In particular, the present invention relates specifically to an apparatus and method for forming a spiral spline groove and exit port for a locking threaded pipe joint. The invention comprises a custom machine tool for manufacturing a sealed spiral connection by machining the bell and spigot end of a length of pipe. The rotating cutter is adapted to cut a recessed spiral groove and exit port in the inside of the bell of the pipe or machine the external groove on the male end of the pipe. The cutter is adapted to float on the surface contour of a pipe to allow for variations in the shape and wall thickness of the pipe. This provides for a consistent depth for the cut in the wall of the pipe without regard to the symmetry or consistency of the circular cross section of the pipe. Another unique aspect of the invention is the use of a lead screw to move an assembly having the motor fixed directly to the cutter without an expansion joint. 
   2. Description of the Known Art 
   As will be appreciated by those skilled in the art, a circular spline may be used to join sections of pipe. Details of a typical flat circular groove are known in the prior art, but the use of a spiral spline and exit port and the machines for forming them are not known for pipe joints. 
   Consideration should be given to Class 82, Turnings which includes subject matter relating to includes severing or cutting (off and/or out) of work of predetermined section (and/or size) by cutting movement(s) of tool and work including (1) relative rotation of either or both about an axis passing through the work and (2) relative translation of either or both substantially normal or parallel to said axis during cutting. Subclasses to be considered in Class 82 include: Subclass 1.2 which is directed to apparatus or process including a rotating assemblage which is adapted to sever portions from the inside of a hole in material by a cutting means which is moving radially relative to the axis of rotation of the assemblage while simultaneously turning about that axis; Subclass 1.3 which is directed to apparatus or process for forming or finishing a noncircular (e.g., elliptical, square) hole; Subclass 110 which is directed to lathes specially adapted for removing material from an externally threaded fastener; and Subclass 113 which is directed to a lathe which is readily transportable or movable and which is specially designed for rotating and cutting hollow cylindrical work generally used for conveying fluids. 
   Examples of these technologies are provided in the following patents and published applications as a basis in these technologies to understand the present invention: U.S. Pat. No. 2,849,926, issued to Burgsmuller on Sep. 2, 1958; U.S. Pat. No. 3,545,018, issued to Peterson on Dec. 8, 1970; U.S. Pat. No. 3,699,828, issued to Piatek et al. on Oct. 24, 1972; U.S. Pat. No. 4,066,380, issued to Beck et al. on Jan. 3, 1978; U.S. Pat. No. 4,186,631, issued to Grider on Feb. 5, 1980; U.S. Pat. No. 4,250,775, issued to Jerue et al. on Feb. 17, 1981; U.S. Pat. No. 4,643,057, issued to Hall et al. on Feb. 17, 1987; U.S. Pat. No. 4,758,121, issued to Kwech on Jul. 19, 1988; U.S. Pat. No. 4,770,074, issued to Kwech on Sep. 13, 1988; U.S. Pat. No. 6,086,297, issued to Lotfi on Jul. 11, 2000; U.S. Pat. No. 6,276,244, issued to Fisher et al. on Aug. 21, 2001; and U.S. Patent Application Pub. No. US 2001/0001935 filed by Wilk, Jr. et al. with a Pub. Date of May 31, 2001. 
   U.S. Pat. No. 2,849,926 issued to Burgsmuller on Sep. 2, 1958 discloses a thread cutting device. This patent describes the use of a lathe for spinning a work piece 23 and operating a drive screw (not numbered) for moving a carriage 3 holding a cutting tool 8 driven by a motor 13. The unique aspect of this patent is the oscillation of the cutting tool to provide for increased cooling time by reducing the amount of cuts taken by the cutting tool on each rotation. The eccentric placement of the cutting tool in relation to the work piece allows for the cutting of a perfectly cylindrical thread across the interior of the work piece. 
   U.S. Pat. No. 3,545,018 issued to Peterson on Dec. 8, 1970 discloses a method and apparatus for cutting multiple threads in large work pieces. This patent shows the utilization of a cutter head 18 which includes a thread cutting tool 54 operated by hydraulic motor 50. The movement of the cutter head into the central bore of the work piece is controlled by a lead screw driven by a worm nut connected to a stationary motor. 
   U.S. Pat. No. 3,699,828 issued to Piatek et al. on Oct. 24, 1972 discloses a pipe groover. This patent describes the use of guide rollers 23 which are spring loaded to cooperate with support rollers 22 to accommodate any unevenness in the wall of a pipe being machined. The rollers 22 are locked into position by locking nuts 97 which fixably position the pipe in relation to the cutting head. 
   U.S. Pat. No. 4,758,121 issued to Kwech on Jul. 19, 1988 describes a boring machine. This patent describes the use of an internal self-centering chuck 10 for positioning a tool head 14 off the central axis of a pipe. Rotational movement of the tool head is performed through hydraulic motors mounted within the self-centering chuck 10. Axial movement of the tool cutting head is provided by a servomotor mounted within the rotatable drive shaft 12. 
   U.S. Pat. No. 6,086,297 issued to Lotfi on Jul. 11, 2000 describes an apparatus for forming grooves in bell-shaped pipes. This patent describes the use of cutters 97 for forming grooves of a uniform depth on the interior wall of a bell-shaped portion of a pipe. The device also uses a groove depth limiting means which is attached to a strain gauge or other force sensing means for controlling the cutting depth of the cutters in accordance with the face of the interior wall of the pipe. 
   Each of these patents and the published application are hereby expressly incorporated by reference in their entirety. 
   These prior art patents fail to recognize the problems with their designs for cutting a circular cross planar groove substantially or completely around the wall of a pipe. This cross planar groove greatly weakens the pipe in the groove area and results in failure points when the pipe is hung by the joint in applications such as well casings. Additional problems are encountered because several of the prior art pipes may rotate in relation to each other even when the joint is completed. Thus, it may be seen that these prior art patents are very limited in their teaching and utilization. A spiral spline groove and exit port machining apparatus is needed to overcome these limitations to build the parts for constructing a spiral spline pipe joint with improved cross sectional strength of the pipe and reduced twisting of the assembled joint. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a spiral spline pipe groove forming apparatus for machining an end of a first plastic pipe having surface contour inconsistencies. In accordance with one exemplary embodiment of the present invention, the spiral spline groove forming apparatus uses a base for supporting a releasable pipe clamp that holds the end of the pipe. The clamp holds either the outside end of the pipe for machining inside the bell housing, or holds a portion of the pipe distal from the end to allow for machining the outside surface of the male end of the pipe. The spiral spline groove, having an associated groove depth and groove distance, is machined into the end of the pipe by a spiral groove machining assembly that is also supported by the base. The groove machining assembly includes a machining extension that is fixed to a surface tracker that may be used to follow the irregular surface contours of a plastic pipe to control the groove depth of the spiral spline groove. By using a spiral spline and following the contours of the surface of the pipe, consistency of the groove and the integrity of the pipe is maintained through the pipe joint. 
   In one embodiment, the pipe clamp is designed to hold the bell of a pipe where the pipe clamp has a clamp depth equal to the distance of the spiral spline groove along the end of the pipe. In this manner, the pipe clamp can support the pipe during the machining operation along the entire distance of the spiral spline groove. 
   In another embodiment, the releasable pipe clamp is constructed using a first clamp jaw that includes at least one movable shell adapted to fit the plastic pipe. The movable shell is positioned by a clamp frame. The movement of the shell is controlled by a shell drive that is adapted to clamp and release the shell against the end of the pipe. 
   Consistency in forming the pipe joints is enhanced in another embodiment by utilizing an end stop connected to the first clamp jaw that provides a stop for repetitive positioning of the end of the pipe. 
   Yet a further advantage is found in the ability to change out the size of the jaws and reposition the machine assembly for use with different sizes of pipes. One aspect of this ability is found in a jaw interchange assembly adapted to releasably engage different clamp jaws for different sizes of pipes. 
   Unique aspects of the spiral groove machining assembly also include the use of a rotational assembly base adapted to provide a pivot support and biasing spring to pivotally bias the machining extension. A machining head having a rotational cutter is mounted to the machining extension and this is used in combination with an adjustable groove depth positioning extension that can control the diameter of the cut for the spiral spline groove. This is done by biasing the machining extension against the adjustable groove depth positioning extension. The contact point between the machining extension and the positioning extension may be controlled by using a slide base connected to the machining extension. The spring and pivot bias the slide base against an adjustable slide ramp connected to a linear slide actuator mounted on a slide arm base. The slide arm base is supported off of the rotational assembly base. By controlling the contact point of the machining extension against the adjustable groove depth positioning extension, the machining extension may be selectively positioned against the pipe. If fully extended, then the surface tracker may be used to contact the surface contour of the pipe. One advantage of this control is that an initial cut can be made without using the surface tracker. This forms a reduced groove depth pass to ease the burden placed on the cutter. A subsequent full groove depth pass can then be made using the surface tracker positioned against the surface contours of the pipe to follow the surface irregularities. 
   Another advantage of the present invention is found in an embodiment of the spiral spline pipe groove forming apparatus which uses an exit port machining assembly supported by the base that is adapted to form an exit port extending from the spiral groove. The exit port machining assembly is mounted on the side of the clamp and is aligned to access the bell of the pipe through a cutting access defined in the releasable pipe clamp. 
   The exit port machining assembly uses a rotational drive for powering a rotational cutting head. The rotational cutting head is extended and retracted by a head displacement drive. In order to ensure that the exit port aligns with the spiral spline groove for different sizes of pipes, a port depth adjustment device is used to control the depth of the cut for the exit port. A further adjustment is provided by a diameter adjustment device adapted to align the rotational cutting head with the spiral spline groove. In the preferred embodiment, the rotational cutting head is aligned to form an exit port tangent to the spiral spline groove. 
   Yet a further embodiment of the present invention teaches a unique drive for the assembly that uses a rotational linear displacement drive. Instead of using an expandable drive shaft, the rotational linear drive is fixed to the spiral groove machining assembly. The rotational linear displacement drive includes a rotational movement source and linear movement is provided converting this rotational movement into a linear movement with a fixed rotational-to-linear converter. The rotational-to-linear converter is a threaded rod passing through a fixed position ball joint type of bearing. This system is unique because the rotational motor is mounted on a slide bearing connected to the base so that the rotational motor is linearly fixed to the cutting head and moves with the linear motion of the cutting head. The preferred embodiment also a reduction gear box connected between the rotational movement source and the rotational-to-linear converter for lower revolutions of the output shaft from a conventional motor. 
   Finally, another unique aspect is provided by controlling tool chatter by using a substantive diameter bearing support connected to the base and adapted to support the machining extension during both rotational and linear displacement of the machining extension. The substantive diameter bearing provides enhanced support and increased control for the machining extension to keep tool chatter to a minimum while allowing easy change out of different machining extensions for different sizes of pipes. 
   These and other objects and advantages of the present invention, along with features of novelty appurtenant thereto, will appear or become apparent by reviewing the following detailed description of the invention. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     In the following drawings, which form a part of the specification and which are to be construed in conjunction therewith, and in which like reference numerals have been employed throughout wherever possible to indicate like parts in the various views: 
       FIG. 1  is a side view of an exemplary embodiment of the spiral groove and exit port forming apparatus. 
       FIG. 2  is a clamp end view of an exemplary embodiment of the spiral groove and exit port forming apparatus. 
       FIG. 3  is a displacement drive end view of an exemplary embodiment of the spiral groove and exit port forming apparatus. 
       FIG. 4  is a side view of the spiral groove machining assembly. 
       FIG. 5  is a top view of the spiral groove machining assembly. 
       FIG. 6  is a machine head end view of the spiral groove machining assembly. 
       FIG. 7  is a side view of the exit port machining assembly. 
       FIG. 8  is a top view of the exit port machining assembly. 
       FIG. 9  is a rotational drive end view of the exit port machining assembly. 
       FIG. 10  is an exploded perspective view of a spiral spline pipe joint. 
       FIG. 11  is an assembled perspective view of a spiral spline pipe joint. 
       FIG. 12  is an exploded side view of a spiral spline pipe joint. 
       FIG. 13  is a cutaway view of an assembled spiral spline pipe joint. 
       FIG. 14  is an exemplary view of the different depths achievable for the spline groove. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention is a spiral spline pipe groove forming apparatus  126  designed for forming the ends of a spiral spline pipe joint  103  shown in  FIG. 10 . A short explanation of this spiral spline joint  103  is provided as a basis for understanding the spiral spline pipe groove forming apparatus  126  of the present invention. 
     FIGS. 10 through 13  show the parts and assembly for joining the male and female ends  102  of plastic pipes  100  to form a spiral spline pipe joint  103 . First, a gasket  94  is inserted into the bell  96  of the joint  103 . Then the male cylinder  98  is inserted into the bell  96  until it reaches the gasket  94 . Note the untouched gasket seat and recessed nature of the groove  108  on the male cylinder  98 . The bell  96  and the male cylinder  98  are then rotated until the groove  108  on the exterior of the male cylinder  98  aligns with the groove  108  on the interior of the bell  96 . A spline  92  is then inserted into the aligned grooves  108 . The spiral spline  92  and groove  108  combination forms a thread connecting the male cylinder  98  and the bell  96 . The male cylinder  98  may then use the thread to screw into the bell  96  to overcome the gasket  94  pressure. The male cylinder  98  is inserted until the groove  108  on the male cylinder  98  reaches the inside of the exit port  118 . The spline  92  may then be further inserted into the aligned grooves  108  until the spline  92  extends out of the exit port  118 . The extension of the spline  92  out of the exit port  118  will work with the end of the groove on the male part of the pipe joint to lock the pipes  100  together. 
   As noted in  FIGS. 10 through 13 , grooves  108  and an exit port  118  are formed in the ends  102  of the pipe  100 . Each plastic pipe  100  has a male or female end  102  having an external diameter  104  and an internal diameter  106 . Each end  102  has a spiral spline groove  108  formed in either the internal or external surface contours  122 . While the surface contours  122  generally seem smooth on the polyvinylchloride pipe used in this type of pipe joint  103 , these surface contours  122  have raised and lowered portion and are not uniform around the axis of the pipe. These irregularities in the surface contours  122  cause problems when machining the pipe  100  to form the ends  102  for the joint  103 . For example, a perfect cylindrical cut in a non-cylindrical surface causes both inadequate depth and excessive depth problems for the cut and may lead to assembly problems or failure of the pipe joint  103 . The spiral spline groove  108  has a groove depth  110  that needs to be consistent so that the spline  92  may be inserted and securely hold the pipe joint  103  without excessive play. Thus, it becomes critical to have proper depth  110  regardless of the surface contours  122 . Note that the spline groove has an axial groove distance  116  defined by the length of the groove  108 , the pitch of the groove  108  and the associated diameter  104 ,  106  of the pipe  100 . Further note that the groove  108  must be recessed on the male cylinder  96  to provide a gasket seat for a sealed joint  103 . In addition to the groove  108 , a bell  98  of a pipe joint  103  will have an exit port  118  machined in connection with the groove  108  to exit and catch the end of the spline  92 . The exit port  118  has a port depth  120  which is shown in its preferred embodiment as passing all the way through the bell  98  to the outside diameter  104  of the bell  98 . 
     FIG. 1  is a side view of an exemplary embodiment of the spiral groove and exit port forming apparatus  126  of the present invention.  FIG. 2  provides a clamp end view, and  FIG. 3  is a displacement drive end view of the spiral groove and exit port forming apparatus  126 . 
   The spiral spline pipe groove forming apparatus  126  is mounted on a support base  128  including a base plate  1  mounted on a base plate frame weldment  2 . Each of the devices are secured to the base plate  1  using socket head cap screws  53  and dowel pins  54 . 
   The spiral spline pipe groove forming apparatus  126  includes a releasable pipe clamp  130 , a spiral groove machining assembly  150  using a machining extension  152  powered by rotational linear displacement drive  192 , and an exit port machining assembly  178 . The releasable pipe clamp  130  is used to hold either the bell or cylindrical ends  102  of pipes  100  for machining. The spiral groove machining assembly  150  rotates around an axis  151  to cut either the interior or exterior surface of the end  102  of the pipe  100 . The rotational linear displacement drive  192  has an output shaft fixed to the spiral groove machining assembly  150  and uses a rotational motor to create both the rotational movement of the machining assembly  150  around the pipe axis  151  and the linear movement along the pipe axis  151  to create the spiral groove  108 . Finally, the exit port machining assembly  178  is used to drill the exit hole  118  into the pipe bell  96  so that the exit port  118  aligns with the spiral groove  108  on the inside of the bell  96 . 
   As shown in  FIGS. 1 and 2 , the releasable pipe clamp  130  has a clamp frame  138  mounted on the base  128 . The clamp frame  138  is constructed from a clamp frame top plate  21 , left hand clamp frame side plate  29 , right hand clamp frame side plate  30 , and clamp frame lower plate  43 . Mounted inside the clamp frame  138  is a clamp jaw  134  formed from a movable shell  136  mounted over a fixed shell  137 . Different sizes of clamp jaws  134  may be used for clamping different sizes of pipes  100  including differences in the pipe bell  98  and the cylindrical end  96  of the pipe. The a movable shell  136  and fixed shell  137  are constructed as part of a jaw interchange assembly  142  using cross over plates  141  and L-shaped shoulders  143  to hold the shells  136 ,  137  in position and allow for easy change out from one size of clamp jaws  134  to another. 
   The moveable shell  136  is constructed from an upper clamp block  44  mounted to an upper clamp plate  22  and supported by upper clamp side blocks  23 . The moveable shell  136  uses the upper clamp side blocks  23  to slide on clamp rods  139  mounted within the clamp frame  138 . The moveable shell  136  is positioned on the clamp rods  139  by a shell drive  140  shown as an air actuated clamp cylinder  46 . As the cylinder  46  extends, the moveable shell  136  clamps the pipe against the fixed shell  137 . As the cylinder  46  retracts, the moveable shell  136  releases the pressure against the fixed shell  137  to allow removal of the pipe  100 . 
   The fixed shell  137  is constructed from a lower clamp block  45  mounted by left hand lower clamp side block  27  and right hand lower clamp side block  28  inside the clamp frame  138 . An end stop  144  is mounted on the fixed shell  137  to control the positioning of the pipe end  102 . As may be seen in  FIG. 2 , the fixed shell  137  also defines a cutting access  146  so that the exit port  118  may be formed in a bell type of pipe end  102 . A drill bushing  62  may be used to help steady the drill bit  61 . 
   The clamp depth  132  shown in  FIG. 1  is sized to be able to support a bell  98  type of pipe end  102  along the entire length of the groove  108  when an internal cut is needed. When machining the exterior of a male cylindrical  96  type end, the clamp  130  is placed farther away from the machining extension  152  so that the clamp  130  holds the distal or back portion of the pipe  100  so that the end  102  is exposed for machining on the external portion of the pipe  100 . 
     FIGS. 1 and 3  provide an overview of the spiral groove machining assembly  150  using a machining extension  152  powered and positioned by a rotational linear displacement drive  192 . The machining extension should be small enough to cut the groove inside a bell end of a pipe and long enough to cut the recessed groove on the male cylinder pipe end. As seen in  FIGS. 4 ,  5 , and  6 , the machining extension  152  uses a machining head  154  having a rotational cutter  156  and a surface tracker  158 . The machining extension  152  is mounted by socket head cap screw  76  to a rotational assembly base  160  shown as spindle  8  mounted in spindle housing  6  and supported by bearing  72 . The rotational assembly base  160  is connected by a dowel pin  75  to the modified lead screw  70  protected by protective bellows  77  secured by hose clamps  78 . In this manner, the entire rotational assembly base  160  and all of the connected assemblies rotate and move linearly with the modified lead screw  70 . As will be explained in more detail later, the modified lead screw  70  rotates like the bar of a c-clamp inside the fixed position of the ball support housing  7  such that the threads on the lead screw  70  cause the entire rotational assembly base  160  to both rotate and move linearly along the axis  151  of the pipe  100 . Thus, the entire rotational assembly base  160  both rotates around the central axis  151  of the pipe  100  and moves linearly along the length of the pipe axis  151  to from the spiral nature of the groove  108 . 
   As best seen in  FIG. 4 , machining extension  152  is mounted on a pivot system  153  and biased by a spring  42  supported off of the rotational assembly base  160 . The machining extension  152  uses a tool holding arm  9  that is mounted to the tool mount plate  18  by dowel pin  36  supported off of tool pivot block  12  using a shoulder screw  34  rotating in a bronze bushing  35 . This provides for the necessary reach for cutting the male pipe end groove  108  and also provides a suspension system for the machining extension  152 . The tool holding arm  9  is biased by spring  42  which is supported off of spring support block  14 . Spring support block  14  is connected to the tool mount plate  18  by socket head cap screw  76 . 
   Machining extension  152  uses a cutter  32  rotated by a right angle die grinder  31 . The depth of the cut of the groove  108  in relation to the surface tracker  158  is adjusted by socket set screw  37 . Surface tracker  158  includes a tool guide  17  mounted by socket set screw  39  to tool guide mount arm  10  and connected into the machining extension  152  using tool guide mount block  11  with extending arm side plates secured by bolt head cap screws  38 . 
   The entire machining extension  152  is positioned by an adjustable depth positioning extension  162  that controls the position of the machining head  154  and selectively uses the surface tracker  158  for following the surface contours  122  of the pipe end  102 . The machining extension  152  may make several passes before achieving the depth of the grooves  108 . As noted in  FIG. 14 , the grooves  108  may be cut in multiple passes such as an initial reduced depth pass  112  and a subsequent full depth pass  114  to cut the groove depth  110 . The structure to perform this feat is shown in  FIG. 4 . Thus, the adjustable depth positioning extension  162  uses a slide base  164  connected to the machining extension  152  shown as a tilt cylinder contact plate  15  mounted by socket head cap screw  40  to tool holder arm  9 . This provides a basic contact point for the tool holder arm  9 . The slide base  164  is biased by the spring  42  against a varying bias stop  166 . The varying bias stop  166  uses an adjustable slide ramp  168  positioned by a linear slide actuator  170  mounted on a slide arm base  172  connected to the rotational assembly base  160 . The varying bias stop is proved by the angled form of the tilt cylinder contact block  16  used to move the tilt cylinder contact plate  15 . First, a base is provided to push against. This is provided by the tilt cylinder mount block  13  connected to tool mount plate  18  by a socket head cap screw  40 . Tilt cylinder  33  is then mounted to the tilt cylinder mount block  13  by socket head cap screw  41  and is used to extend and retract the angled surface of tilt cylinder contact block  16 . This provides a linear slide actuator  170  that may be used to extend and retract the angled surface of the tilt cylinder contact block  16 . As the linear slide actuator  170  extends, the adjustable slide ramp  168  will cause the machining extension  152  to pivot upward. Similarly, as the linear slide actuator  170  retracts, the adjustable slide ramp  168  will allow the biased machining extension  152  to pivot downward. When this is related to the positioning of the machining extension  152  to the pipe end  102  shown in  FIG. 1 , one may easily see how the contact of the machining head  154  with the pipe and the depth of the cut may be controlled. If the adjustable slide ramp  168  is sufficiently retracted, the bias of the spring  42  will force the machine head against the pipe end  102  until the surface tracker  158  contacts the surface contour  122  of the pipe end  102 . The surface tracker  158  will then follow the surface contour  122  as the entire machining extension  152  and associated adjustable depth positioning extension  162  mounted on the rotational assembly base  160  is rotated and extended by the rotational linear displacement drive  192 . 
   As shown in  FIG. 1 , bearing  72  is used as a substantive diameter bearing support  174  to support the rotational assembly base  160  inside the ball nut housing  7 . This substantive diameter bearing support  174  has a diameter approximating that of the pipe end  102  being machined. This substantive diameter minimizes the effect of bearing play or tolerance within the support  174  to reduce tool chatter and improve the quality of the cut for the groove  108 . 
     FIGS. 1 and 3  provide clear views of the operation of the rotational linear displacement drive  192 . This operates very similarly to the moveable clamping pad in a c-clamp acting against the fixed bearing of the clamp. As the shaft is rotated, the threads on the shaft and the fixed position of the bearing cause a linear movement of the shaft. 
   The rotational linear displacement drive  192  uses a rotational movement source  194  including a rotational motor  196 , shown as electric motor  68 , connected to a reduction gear box  200  by hex head cap screws  50 . The motor  196  and the gear box  200  are mounted on a slide bearing  198 . The electric motor  68  is mounted using a hex head cap screw  73  to a gear box slide plate  3 . The gear box slide plate  3  is held in position by the slide plate retainer  4  secured to the base plate  1  by socket head cap screw  57 . The gear box slide plate  3  rides on replaceable wear strips  5  held to the base plate  1  by flat head cap screw  65 . This allows the motor and gear box to slide linearly along the pipe axis  151 . The reduction gear box  200  is shown as a typical gear reducer  67  and is connected to the rotational-to-linear converter  202  by the threaded shaft  204  formed from a modified lead screw  70 . 
   The rotational-to-linear converter  202  uses a threaded shaft  204  connected to the motor through the shaft coupling  69 . The threaded shaft  204  is shown as a modified lead screw  70  passing through a ball nut  7  mounted in a fixed position ball nut support  206  and held in place by hex head cap screw  74 . The linear displacement is caused by the threads on the modified lead screw  70  rotating inside the fixed position of the ball nut  7 . This would be the base of the c-lamp. Through this connection, the rotational to linear converter  192  controls the linear position of the electric motor  68 , linearly fixed to the machine extension  152 , using the slide mounting of the rotational motor  196  and gear box  200  to allow linear displacement  208 . The rotation is provided by the rotational movement created by the rotational motor  196 . 
     FIGS. 2 ,  7 ,  8 , and  9  show the exit port machining assembly  178 . The exit port machining assembly  178  uses a rotational drive  180  for powering a rotational cutting head  182 . The rotational drive  180  is shown as an auto feed drill  58  having a rotational cutting head  182  including a drill chuck  60  operating a drill bit  61 . The extension and retraction of the auto feed drill  58  is used as a head displacement drive  184  for the insertion and retraction of the drill bit  61 . The amount of insertion is controlled by a groove depth adjustment device  186 . Basically, the maximum extension of the drill  58  is adjusted to the achieve the proper depth. The drill is then clamped in position using the drill clamp  59 . This provides the groove depth adjustment device  186  for controlling the depth of the insertion. 
   The drill clamp  59  is supported by hex head cap screw  64  connected to the diameter adjustment device  188 . The diameter adjustment device  188  allows for vertical adjustment of the position of the auto feed drill  58  for different diameters of pipes  100  and variations in the clamping setup. Vertical adjustment is performed using an adjuster slide  66  connected by a flat head cap screw  63  to a drill unit adjuster mount  19  attached to the base plate  1 . The adjuster slide  66  uses a handle on a threaded rod to adjust the vertical position of the clamp adaptor plate  20 . The threaded rod and the dovetail shape of the adjuster slide  66  is easily seen in  FIG. 8 . The clamp adaptor plate  20  of the adjuster slide  66  is connected to the drill clamp  59  through the flat head cap screw  65 . 
   The following list details reference numbers used in the drawings:
         base plate  1     base plate frame weldment  2     gear box slide plate  3     slide plate retainer  4     wear strip  5     spindle housing  6     ball nut housing  7     spindle  8     tool holding arm  9     tool guide mount arm  10     tool guide mount block  11     tool pivot block  12     tilt cylinder mount block  13     spring support block  14     tilt cylinder contact plate  15     tilt cylinder contact block  16     tool guide  17     tool mount plate  18     drill unit adjuster mount  19     drill unit clamp adaptor plate  20     clamp frame top plate  21     upper clamp plate  22     upper clamp side block  23     pipe stop  24     clamp block stop  25     clamp lock  26     left hand lower clamp side block  27     right hand lower clamp side block  28     left hand clamp frame side plate  29     right hand clamp frame side plate  30     die grinder  31     cutter  32     tilt cylinder  33     shoulder screw  34     bronze bushing  35     dowel pin  36     socket set screw  37     bolt head cap screw  38     socket set screw  39     socket head cap screw  40     socket head cap screw  41     spring  42     clamp frame lower plate  43     upper clamp block  44     lower clamp block  45     clamp cylinder  46     bearing  47     bearing shaft  48     bolt head cap screw  49     hex head cap screw  50     bolt head cap screw  51     dowel pin  52     socket head cap screw  53     dowel pin  54     bolt head cap screw  55     dowel pin  56     socket head cap screw  57     auto feed drill  58     drill clamp  59     drill chuck  60     drill bit  61     drill bushing  62     flat head cap screw  63     hex head cap screw  64     flat head cap screw  65     adjuster slide  66     gear reducer  67     drive motor  68     shaft coupling  69     modified lead screw  70     ball nut  71     bearing  72     hex head cap screw  73     hex head cap screw  74     dowel pin  75     socket head cap screw  76     protective bellows  77     hose clamp  78     spline  92     joint gasket  94     bell  96     male cylinder  98     a plastic pipe  100     an end  102     spiral spline pipe joint  103     an external diameter  104     an internal diameter  106     a spiral spline groove  108     a groove depth  110     an initial reduced depth pass  112     a subsequent full depth pass  114     a distance  116     an exit port  118     a port depth  120     surface contours  122     A spiral spline pipe groove forming apparatus  126     a base  128     a releasable pipe clamp  130     a clamp depth  132     a clamp jaw  134     a movable shell  136     a fixed shell  137     a clamp frame  138     clamp rods  139     a shell drive  140     cross over plates  141     a jaw interchange assembly  142     L-shaped shoulders  143     an end stop  144     a cutting access  146     a spiral groove machining assembly  150     a pipe axis  151     a machining extension  152     a pivot  153     a machining head  154     a rotational cutter  156     surface tracker  158     a rotational assembly base  160     an adjustable depth positioning extension  162     a slide base  164     a varying bias stop  166     an adjustable slide ramp  168     a linear slide actuator mounted  170     a slide arm base  172     an substantive diameter bearing support  174     an exit port machining assembly  178     a rotational drive  180     a rotational cutting head  182     a head displacement drive  184     a groove depth adjustment device  186     a diameter adjustment device  188     a rotational linear displacement drive  192     a rotational movement source  194     a rotational motor  196     slide bearing  198     a reduction gear box  200     a rotational-to-linear converter  202     a threaded shaft  204     a ball nut support  206     linear displacement  208         

   From the foregoing, it will be seen that this invention is well adapted to obtain all the ends and objects herein set forth, together with other advantages which are inherent to the structure. It will also be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. Many possible embodiments may be made of the invention without departing from the scope thereof. Therefore, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.