Patent Publication Number: US-11660677-B2

Title: Tooling assemblies for lathe machines, CNC threading lathes, and methods of milling threads in tubular workpieces

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to milling threads on tubular workpieces, and more particularly to milling threads on pipes and couplings for use in oil and gas wells using lathes. 
     2. Description of Related Art 
     Threaded pipes and couplings are commonly used to conveying various types of fluids, for example in oil and gas production. The threads are typically cut such that a fluid-tight connection can be established and maintained during service, male threads generally being cut into the exterior surface of the pipe and female threads cut into the interior surface of the coupling to form a threaded connection. The male and female threads are typically cut with precision sufficient to limit the risk of leakage and/or failure under the downhole conditions, such as when the connection is exposed the high fluid pressures required in fracking operations. 
     Cutting threads in pipes and couplings generally entails employing a turning operation. The pipe or coupling is typically seated in a lathe and rotated relative to a cutting tool. While the pipe or coupling rotates the cutting tool is pressed against the pipe or coupling surface such that a surface of the cutting tool removes an elongated, wire-like chip from the pipe or coupling. The cutting tool may be advanced relative to the rotating pipe or coupling to define the desired helical pitch of the threads. 
     One challenge to cutting threads using turning operations is managing the wire-like chips cut from the workpiece during thread-cutting. During male thread-cutting the wire-like chips can form a mass, i.e., a bird nest, on the exterior of the pipe or coupling and carried by the rotating pipe or coupling. During female thread cutting the wire-like chips can aggregate as a mass within the interior of the pipe or coupling to form a birds nest. In either case the bird nest can require clearance, typically through operator intervention, such as by the lathe operator using a metal hook to clear or remove the bird nest. In these cases, the bird nest is often cleared while the lathe is still in operation, which poses serious safety risks as the cutting tool continues to rotate in proximity to the worker&#39;s metal hook. Alternatively, the lathe may be stopped to clear the bird nest obstruction. However, stopping operation for each bird nest also severely slows the production time, particularly when threading the countless coupling/pipe needed for the oil and gas industry. As will be appreciated, the wire-like chips forming the bird nest can pose a hazard to the operator due to sharp edges and spring action of the wire-like chips. The wire-like chips can also present a hazard to threads cut into pipe or coupling, movement of the birds nest across the threads tending to damage the freshly cut threads. 
     Various tools and techniques have been developed in efforts to manage the wire-like chips formed during turning. For example, chip breaker devices have been developed to break the wire-like chips as they form, generally to limited effect. Turning speed and/or feed rate adjustments have also been attempted, also with limited effect. Bird nest formation remains common in turning operations and is generally considered unavoidable during thread-cutting. 
     Such conventional methods and systems for cutting threads in pipes and couplings using turning operations have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved methods and systems for cutting threads in pipes and couplings. The present disclosure provides a solution for this need. 
     SUMMARY OF THE INVENTION 
     A tooling assembly for a lathe machine includes a tool platform, a milling tool holder, and a milling tool drive. The tool platform is configured to be mounted on the lathe machine. The milling tool holder is fixedly secured to the tool platform and is workable to releasably secure a thread milling tool therein. The milling tool drive is operatively connected to the milling tool holder and is operable to rotate the milling tool holder independently of a work holder to mill threads on the workpiece when a pipe thread milling tool is secured in the milling tool holder. 
     In certain embodiments a static tool holder can be mounted on the tool platform. The static tool holder can mounted to the on the tool platform at a location offset from the milling tool holder. A thread milling tool can be supported for rotation relative to the tool platform by the milling tool holder. A static tool can be fixedly secured to the tool platform. The static tool can be coupled to the tool platform by the static tool holder. 
     In accordance with certain embodiments, a mill spindle can be fixed in rotation relative the milling tool holder. A spindle housing can be fixed to the tool platform and rotatably support the milling tool holder. A milling tool drive can be operatively connected to the milling tool holder and supported by the tool platform. A milling tool drive bracket can couple the milling tool drive to the tool platform. An adapter plate can couple the milling tool drive to the tool platform. A motor cam and a spindle cam interconnected by a mill drive belt can operably connect the milling tool drive to the mill too holder. 
     A computer numerical control (CNC) threading lathe includes a base defining a z-axis and an x-axis angled and movable relative to the z-axis, a work holder rotatable relative to the base, and a tooling assembly as described above. The tooling assembly is movable relative to the work holder along the z-axis. The tool platform of the tooling assembly is movable along the x-axis between a thread milling position and a turning position. The thread milling position is selected to position a thread milling tool rotatably supported by the tool platform against a tubular workpiece supported by the work holder. The turning position is selected to position a static tool fixedly supported by the tool platform against the tubular workpiece supported by the work holder. 
     In certain embodiments a thread milling tool can be supported for rotation by the milling tool holder and a static tool fixedly secured to the tool platform. A milling tool drive can be operatively connected to the milling tool holder. The milling tool drive can be supported by the tool platform. A milling tool drive bracket can couple the milling tool drive to the tool platform. An intervening adapter plate can couple the milling tool drive to the tool platform. A tubular workpiece, such as a pipe or coupling, can be supported for rotation in the work holder. 
     In accordance with certain embodiments a work beam can be movable along the z-axis of the CNC threading lathe. A spindle motor can be fixed relative to the work beam. A beam spindle can couple the spindle motor to the tool platform for moving the tool platform along the x-axis between a milling position and a turning position. The milling position and the turning position can both be disposed along a x-axis of the CNC threading lathe. A beam spindle can be operably connected to the work beam for moving the work beam along the z-axis of the CNC threading lathe. 
     It is contemplated that, in certain embodiments, the CNC threading lathe can include a controller. The controller can be disposed in communication with a non-transitory machine readable medium having instructions recorded thereon that, when read by the controller, cause the controller to rotate a tubular workpiece supported in the work holder, rotate a thread milling tool supported in the milling tool holder, and mill threads on the tubular workpiece with the thread milling tool. The threads can be milled by rotating the thread milling tool independently of rotation of the workpiece during milling of the threads on the workpiece. 
     A method of milling threads on a workpiece using a CNC threading lathe includes rotating a workpiece supported in a work holder, rotating a thread milling tool supported in a milling tool holder independently of the workpiece supported in the work holder, and milling threads in the workpiece in a milling operation using the thread milling tool while rotating the workpiece supported in the work holder. 
     In certain embodiments the tool platform can be moved between the milling position and the turning position and material removed from the tubular workpiece in a turning operation following the milling operation. The tubular workpiece can remain in the workpiece holder between the beginning of the thread milling operation and the end of the turning operation. 
     These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures. 
         FIG.  1    is a perspective view of lathe, showing a workpiece with a bird nest formed from wire-like chips cut from the workpiece using a turning operation; 
         FIG.  2    is a schematic view of a threading lathe according to the present disclosure, showing a controller operatively connected to a tool assembly, the tool assembly having both a static tool and a thread milling tool; 
         FIG.  3    is a schematic view of the threading lathe of  FIG.  2   , showing a controller operatively connected to the tool platform for moving the tool assembly and positioning the static tool or the thread milling tool to against a workpiece supported for rotation relative to the threading lathe; 
         FIG.  4    is a perspective view of an exemplary embodiment of a threading lathe, showing a tooling assembly supported for movement along a work beam along an x-axis, the tooling assembly movable with the work beam along a z-axis; 
         FIG.  5    is a perspective view of the threading lathe of  FIG.  4   , showing a drive end of the threading lathe including a work holder drive and a work holder position detector for c-axis control of the work holder; 
         FIG.  6    is a perspective view of the threading lathe of  FIG.  4   , showing the supporting the work beam on z-rails and work beam supporting the tooling assembly on x-rails for movement of the tooling assembly along the x-axis and the z-axis, respectively; 
         FIGS.  7  and  8    are perspective views of the tooling assembly of  FIG.  6   , showing a thread milling tool drive carried by the tooling assembly and operably connected to the thread milling tool by a belt and pulley milling tool drive arrangement; 
         FIG.  9    is a perspective view of the threading lathe of  FIG.  4   , showing a tubular workpiece seated in the work holder and static and thread milling tool supported by the tool platform in the static tool holder and milling tool holder, respectively; 
         FIG.  10    is a partial perspective view of the threading lathe of  FIG.  4   , showing the static tool position against the tubular workpiece and removing material from the tubular workpiece; 
         FIG.  11    is a partial perspective view of the threading lathe of  FIG.  4   , showing the thread milling tool cutting threads on an interior surface of the tubular workpiece; and 
         FIG.  12    is a block diagram of a method of milling threads on a workpiece using a threading lathe, showing operations of the method. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a tooling assembly for a threading lathe in accordance with the disclosure is shown in  FIG.  2    and is designated generally by reference character  110 . Other embodiments of tooling assemblies, threading lathes, and methods of milling threads on tubular workpieces in accordance with the disclosure, or aspects thereof, are provided in  FIGS.  3 - 12   , as will be described. The systems and methods described herein can be used for milling threads and on tubular workpieces, such as couplings and pipes for oil and gas wells, though the present disclosure is not limited to pipes and couplings for oil and gas wells nor to pipes and couplings in general. 
     Illustrative embodiments of the present disclosure are described in detail below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of the present disclosure. 
     To facilitate a better understanding of the present disclosure, the following examples of certain embodiments are given. In no way should the following examples be read to limit, or define, the scope of the disclosure. The terms “couple” or “couples” as used herein are intended to mean either an indirect or a direct connection. 
     There is a need for tooling assemblies, computer numerical controlled (CNC) threading lathes, and methods of milling threads on workpieces such as pipes and couplings that reduce (or eliminated entirely) the wire-like chips commonly generated during thread-cutting which aggregate as birds nest about the workpiece exterior or within the workpiece. The present disclosure recognizes and addresses this need. For example, the present systems and methods allow for cutting threads on couplings and pipes for use in oil and gas production operations without creating the long, wire-like chips that can otherwise require containment and/or may form bird nests requiring clearance from within the interior of a pipe or coupling. 
     Referring the  FIG.  1   , a lathe  2  is shown. Lathe  2  has a workpiece  4  seated within the lathe chuck and is shown subsequent to removing material from workpiece  4  using a turning operation. The material contains long, wire-like chips which have aggregated as a mass about workpiece  4  as a birds nest  6 . Birds nest  6  requires clearance prior to the next turning operation. 
     Referring to  FIG.  2    a threading lathe  100 , e.g., a lathe machine, is shown. Threading lathe  100  has a base  102 , a work holder assembly  104 , a work beam assembly  106 , a controller  108 , and a tooling assembly  110 . Work holder assembly  104  includes a work holder  112  and a work holder drive  114 . Work holder  112  is configured support a workpiece  10 , e.g., a coupling or a pipe, for rotation relative to base  102 . Work holder drive  114  is to disposed in communication with controller  108  and is operably connected to work holder  112 , and thereby to a workpiece  10  supported therein, for rotating workpiece  10  relative to base  102 . Rotation is according to a work holder drive signal A received from controller  108 . It is contemplated that threading lathe  100  can be a computer numerical control (CNC) threading lathe, controller  108  configured to operate threading lathe  100  in an autonomous or semi-autonomous mode. 
     A work holder position detector  116  is disposed in communication with work holder assembly  104  to generate a work holder position signal B and controller  108 . It is contemplated that work holder position detector  116  generate a work holder position signal B, which work holder position detector  116  provides to controller  108  for controlling position of work holder  112  during milling of threads  16  on workpiece  10 . It is contemplated that work holder position signal B be suitable such that controller  108  provide c-axis control of work holder assembly  104 , positional control of work holder  112  being on the order of about 0.001 degrees in certain embodiments. 
     Work beam assembly  106  includes a work beam  118  and a work beam drive  120 . Work beam  118  is slideably supported by base  102  for movement relative to base  102  along a z-axis  122 . Work beam drive  120  is operably coupled to work beam  118  and is disposed in communication with controller  108  to move work beam  118  along z-axis  122  relative to base  102  according a work beam drive signal C, which controller  108  generates and provides to work beam drive  120 . 
     Tooling assembly  110  includes a tool platform  124 , a static tool holder  126 , a milling tool holder  128 , and a tool platform drive  130 . Static tool holder  126  is fixed relative to tool platform  124  and is configured to support a static tool  12 , e.g., a lathe tool or a turning tool. Milling tool holder  128  is supported for rotation relative to tool platform  124  and is configured to rotatably support a thread milling tool  14 . A milling tool drive  138  is operably connected to milling tool holder  128  and is configured for rotating milling tool holder  128 , and thereby rotating thread milling tool  14 , according to a milling tool drive signal E received from controller  108 . Milling tool drive signal E is generated by controller  108  and provided to milling tool drive  138  when thread milling tool  14  is positioned against workpiece  10 . 
     Tool platform drive  130  is operably connected to tooling assembly  110  for moving tooling assembly  110  between a turning position  260  (shown in  FIG.  10   ), wherein static tool  12  is positioned against workpiece  10  for removing material from the exterior of workpiece  10 , and a milling position  262  (shown in  FIG.  11   ), wherein thread milling tool  14  is positioned against workpiece  10  for cutting threads in the surface of workpiece  10 . Movement between turning position  260  and milling position  262  is according to a tooling assembly drive signal D, which controller  108  generates and which tool platform drive  130  receives from controller  108 . Movement between turning position  260  and milling position  262  is in a linear movement along at least one of z-axis  122  and x-axis  132 . 
     As will be appreciated by those of skill in the art in view of the present disclosure, positioning static tool  12  against workpiece  10  allows for removing material from workpiece  10  in a turning operation. For example, an inner diameter of pipe or coupling workpiece can be finished by positioning static tool  12  against the pipe or coupling workpiece while rotating the workpiece at a turning speed. As will also be appreciated by those of skill in the art in view of the present disclosure, positioning thread milling tool  14  against workpiece  10  allows for milling threads  16  in a surface of workpiece by rotating the workpiece at a milling speed, rotation of thread milling tool  14  breaking chips generated by the milling operation and preventing formation of a birds nest on workpiece  10 . As will be appreciated by those of skill in the art, this reduces (or eliminates entirely) the need to clear such hazards during workpiece threading, improving efficiency and/or reducing (or eliminating entirely) the hazard that clearing the birds nest from the workpiece. Advantageously, both the turning operation and the milling operation can be performed without removing workpiece  10  from work holder  112 , reducing cycle time to finish inner/outer surfaces, bevel the workpiece end, and cut threads in workpiece  10 . 
     With reference to  FIG.  3    controller  108  is shown. Controller  108  includes a processor  140 , a user interface  142  (e.g. a display and/or a keypad), a network interface  144 , and a memory  146 . User interface  142  allows for a user control threading lathe  100 . Network interface  144  provides communication between controller  108  and work holder drive  114 , work holder position detector  116 , work beam drive  120 , milling tool drive  138 , tool platform drive  130 , and c-axis drive  152 . Communication occurs over a link  148  coupling work holder drive  114 , work holder position detector  116 , work beam drive  120 , milling tool drive  138 , tool platform drive  130 , and c-axis drive  152  with controller  108 . It is contemplated that link  148  can be wired and/or wireless, as suitable for an intended application, to pass therethrough work holder drive signal A, work holder position signal B, work beam drive signal C, tooling assembly drive signal D, mill drive signal E, and c-axis drive signal F. 
     Memory  146  includes a non-transitory machine readable memory with a plurality of program modules  150  recorded thereon that, when read by processor  140 , cause processor  140  to execute certain operations. In this respect it is contemplated that the instructions recorded in the plurality of program modules  150  cause processor  140  to execute the operations of a method of milling threads on a workpiece, e.g., a method  300  of milling threads on a workpiece using a CNC lathe machine (shown in  FIG.  12   ), as will be described. While shown in  FIG.  2    as a controller having a single processor  140  and memory  146  it is to be understood and appreciated that controller  108  can include circuitry, software, or a combination of circuitry and software, as suitable for an intended application. 
     With reference to  FIG.  4   , a threading lathe  200  is shown according an exemplary embodiment. Threading lathe  200  includes a base  202 , a work holder assembly  204 , a work beam assembly  207 , and tooling assembly  208 . Base  202  extends between a work holder end  210  and an tooling assembly end  212 , defines a z-axis  214 , and has a bottom  216  and bed  218 . Bed  218  is angled relative to bottom  216 . In this respect, from the perspective of work holder end  210  or tooling assembly end  212 , bed  218  and bottom  216  define between one another an angle. The angle can be a 45-degree angle. The angle can be less than 45-degrees. The angle can be more than 45-degrees. It is also contemplated that, in certain embodiments, bed  218  can be substantially parallel to bottom  216 , as suitable for an intended application. Although threading lathe  200  is shown and described as a horizontal lathe  200  wherein bed  218  is arranged above bottom  216  relative to gravity, it is to be understood and appreciated that vertical lathes can also benefit from the present disclosure. Examples of suitable threading lathes include Amera-Seiki® “Top Turn” series CNC lathes, available Amera-Seiki, Inc. of Houston, Tex. 
     Two z-rails  220  extend longitudinally along bed  216  between work holder end  210  and tooling assembly end  212 . The two z-rails  220  are each substantially parallel to z-axis  214  and are configured to slideably support work beam assembly  207  for movement along z-axis  214  relative to work holder assembly  204 . Although two z-rails  220  are shown in the illustrated exemplary embodiment it is to be understood and appreciated that threading lathe  200  can have fewer than two z-rails  220  or more than two z-rails  220 , as suitable for an intended application. 
     With reference to  FIG.  5   , work holder end  210  of threading lathe  200  is shown. Work holder assembly  204  is configured to support workpiece  10  (shown in  FIG.  2   ) for rotation relative to base  202 . In this respect work holder assembly  204  includes a work holder  222  with a plurality of chuck teeth  224  and a work holder drive  226 . Work holder  222  is fixed in rotation relative to a work holder spindle  230  and a work holder pulley  232 , which are both supported for rotation by a work holder mount  228 . Work holder mount  228  is in turn fixed relative to base  202  for supporting work holder  222  and the associated assembly. 
     Work holder drive  226  includes a work holder drive motor  234  and work holder drive belt  236 . Work holder drive belt  236  operably connects work holder drive motor  234  to work holder  222  via work holder drive pulley  232  such that, responsive to work holder drive signal A (shown in  FIG.  2   ), work holder  222  rotates in concert with a rotor portion of work holder drive motor  234 . As will be appreciated by those of skill in the art in view of the present disclosure, other types of work holder drive arrangements are contemplated within and are within the scope of the present disclosure, such gear or drive chain arrangements. 
     A work holder position detector  240  is disposed in communication with work holder  222 . Work holder position detector  240  is configured to generate work holder position signal B (shown in  FIG.  2   ), which work holder position detector  240  provides to controller  108  (shown in  FIG.  2   ) for purpose of providing c-axis control of work holder  222 . In the illustrated exemplary embodiment work holder position detector  240  includes an encoder/resolver arrangement connected to work holder mount  228  by a bracket  251 . This is for illustration purposes only and is non-limiting and, as will be appreciated by those of skill in the art in view of the present disclosure, other types of work holder position detectors can be employed by threading lathe  200  and remain within the scope of the present disclosure. 
     With reference to  FIG.  6   , tooling assembly end  212  of threading lathe  200  is shown. Tooling assembly end  212  includes work beam assembly  207 , which has a work beam  242  and a work beam drive  244  (shown in  FIG.  5   ). Work beam  242  is slideably disposed on two z-rails  220  for movement relative to work holder  222  along z-axis  214 . In the illustrated exemplary embodiment work beam drive  244  includes a work beam drive motor  246  that is operably connected to work beam  242  by a work beam ball screw  248 . It is contemplated that work beam drive motor  246  be responsive to work beam drive signal C (shown in  FIG.  2   ) to move work beam  242  relative to work holder  222  along z-axis  214 . As will be appreciated by those of skill in the art in view of the present disclosure, tooling assembly  208  in concert with work beam  242 . As will also be appreciated by those of skill in the art in view of the present disclosure, other types of work beam drives can be employed by threading lathe  200  and remain within the scope of the present disclosure. 
     Work beam  242  defines an x-axis  250  and has a pair of x-rails  252  and a tool platform drive  254 . X-rails  252  extend in parallel with x-axis  250  and are fixed relative to work beam  242 . Tooling assembly  208  is slideably seated on x-rails  252  for movement relative to work beam  242  along x-axis  250 . As will be appreciated by those of skill in the art in view of present disclosure, work beam  242  can include fewer than two x-rails  252  or more than two x-rails  252 , as suitable for an intended application. 
     Tool platform drive  254  is operably connected to tooling assembly  208  and includes a tooling assembly drive motor  256  and tooling assembly ball screw  258  in the illustrated exemplary embodiment. Tooling assembly ball screw  258  connects tooling assembly drive motor  256  to tooling assembly  208  such that, responsive to tooling assembly drive signal D (shown in  FIG.  2   ), tool platform drive  254  moves tooling assembly  208  relative to work beam  242 . In this respect tool platform drive  254  is configured to move tooling assembly  208  between a turning position  260  (shown in  FIG.  10   ) relative to work holder  222 , wherein static tool  12  is positioned against workpiece  10 , and a milling position  262  (shown in  FIG.  11   ) relative to work holder  222 , wherein thread milling tool  14  positioned against workpiece  10 . In the illustrated exemplary embodiment tooling assembly  208  is configured for movement in a linear displacement between turning position  260  and milling position  262 , e.g., as a sled arranged on an incline. It is also contemplated that tooling assembly  208  can be alternatively be mounted in a turret  408  (shown in  FIG.  3   ), tooling assembly  208  moving between turning position  260  and milling position  262  at least in part via a rotary movement by turret  408 . 
     With reference to  FIGS.  7  and  8   , tooling assembly  208  is shown from work holder end  210  and tooling assembly end  212 , respectively. Tooling assembly  208  includes a tool platform  264  with a static tool seat  266  and milling tool seat  268 . A static tool holder  270  is fixed to tool platform  264  by static tool seat  266  for supporting static tool  12  (shown in  FIG.  2   ), and a milling tool holder  272  is fixed to tool platform  264  by milling tool seat  268 . A milling tool drive  274  is operably connected to milling tool holder  272  for rotating thread milling tool  14  (shown in  FIG.  2   ) relative to workpiece  10  at a speed suitable for milling threads  16  (shown in  FIG.  2   ) in workpiece  10 . Milling tool seat  268  is offset from static tool seat  266  along x-axis  250  by an x-axis offset  288  such that one of static tool  12  and thread milling tool  14  are positioned against workpiece  10  during a turning operation or a milling operation for milling threads  16  on workpiece  10 . 
     Milling tool drive  274  includes a milling tool drive motor  276 , a direct-drive mounting bracket  278 , and a direct-drive adapter plate  280 . Milling tool drive motor  276  seats in direct-drive motor mounting bracket  278 . Direct-drive motor mounting bracket  278  in turn seats on direct-drive adapter plate  280  to a milling tool holder mount  282 , milling tool holder mount  282  supporting milling tool holder  272  for rotation with a milling tool holder pulley  284  (shown in  FIG.  8   ). As shown in  FIG.  8   , a rotor of milling tool drive motor  276  is coupled to milling tool holder pulley  284  by a milling tool drive belt  286  such that the rotor of milling tool drive motor  276  and milling tool holder  272  (shown in  FIG.  7   ) rotate in concert with one another to mill threads  16  (shown in  FIG.  2   ) in workpiece  10 . It is contemplated that milling tool drive motor  276  be response to tooling assembly drive signal D (shown in  FIG.  2   ) for purposes of milling threads  16  in workpiece  10 . As will be appreciated by those of skill in the art in view of the present disclosure, the illustrated exemplary direct-drive arrangement allows for the user of a relatively large milling tool drive motor within a relatively small footprint on tool platform  264 . 
     With reference to  FIGS.  9 - 11   , CNC threading lathe  200  is shown cutting threads on an exemplary workpiece, e.g., a coupling workpiece  18 . Referring to  FIG.  9   , coupling workpiece  18  is seated within work holder  222  and fixed therein by chuck teeth  224 . Fixation within work holder  222  by chuck teeth  224  is such that both an exterior surface  20  and an interior surface  22  of coupling workpiece  18  are accessible to static tool  12  and thread milling tool  14 . Tooling assembly end  212  is shown displaced along z-axis  214  and x-axis  250  relative to turning position  260  (shown in  FIG.  10   ) and milling position  262  (shown in  FIG.  11   ). Coupling workpiece  18  is rotated, indicated by rotary arrow R. 
     Referring now to  FIG.  10   , tooling assembly  208  is shown in turning position  260 . Tooling assembly  208  displaces relative z-axis  214  and/or x-axis  250  to arrive at turning position  260  by operation of either (or both) work beam drive  244  and tool platform drive  254 . Once in turning position  260  static tool  12  is positioned against coupling workpiece  18 , allowing static tool to remove material from a surface of coupling workpiece  18  in a turning operation. 
     As will be appreciated by those of skill in the art in view of the present disclosure, static tool  12  is rotationally fixed relative to coupling workpiece  18 . Being rotationally fixed relative to coupling workpiece  18 , rotational movement of coupling workpiece  18  relative to static tool  12  causes static tool  12  to remove material (e.g., a stringer-type chip) from a surface of coupling workpiece  18 . As static tool  12  advances into the interior of coupling workpiece  18  the stringer (or stringer mass) is displaced toward work holder  222 , such as during formation of a bevel on the end of coupling workpiece  18  and/or during skinning of coupling workpiece  18  interior surface  22 . In the illustrated exemplary embodiment static tool is shown removing material from interior surface  22 , tooling assembly  208  progressively advancing along z-axis  214  toward work holder  222  to skin interior surface  22  of coupling workpiece  18 . 
     Once the turning operation is complete tooling assembly  208  is then displaced relative z-axis  214  and/or x-axis  250  by operation of either (or both) work beam drive  244  and tool platform drive  254  to milling position  262 . In milling position  262  thread milling tool  14  is positioned against interior surface  22  of coupling workpiece  18  to mill threads  16  on in interior surface  22  of coupling workpiece  18 . 
     Referring to  FIG.  11   , tooling assembly  208  is shown in milling position  262 . Once tooling assembly arrives at milling positon  262  milling tool drive  274  rotates thread milling tool  14  relative to coupling workpiece  18 . Rotation of thread milling tool  14  relative to coupling workpiece  18 , shown by arrow  24 , causes thread milling tool  14  to mill threads  16  on interior surface  22  of coupling workpiece  18 . Chips  28  cut from coupling workpiece  18  are relatively short due to the relatively small radius of milling tool  14 , chips  28  being readily removed from coupling workpiece  18  and being less apt (if at all) to form a birds nest within coupling workpiece  18 . It is contemplated that the direction of rotation of thread milling tool  14  can be in the same direction as coupling workpiece  18  or in a direction opposite coupling workpiece  18 , as indicated by double-headed  24 . The pitch of threads  16  can be defined by C-axis manipulation, i.e., via operation of a c-axis drive  152  (shown in  FIG.  3   ), using c-axis control signal F (shown in  FIG.  3   ). Alternatively (or additionally), pitch of threads  16  can be defined by movement of thread milling tool  14  along z-axis  214 . 
     As will be appreciated by those of skill in the art in view of the present disclosure, the relatively small diameter of thread milling tool  14  cause chips  28  removed from coupling workpiece  18  to be relatively short in the length. Being relatively short, chips  28  are less likely to aggregate as a mass within the interior of workpiece coupling  18  to form a birds nest, and are amendable to removal as generated. This reduces (or eliminates entirely) the tendency of material removed during thread-cutting operation to form a bird nest within coupling workpiece  18 , the associated hazard posed to the operator, and the potential risk to damage to freshly cut threads  16  by clearing the material removed from interior surface  22 . 
     With reference to  FIG.  12   , a method  300  of milling threads in a workpiece, e.g., threads  16  (shown in  FIG.  2   ) in workpiece  10  (shown in  FIG.  2   ), is shown. Method  300  includes rotating the workpiece in a work holder, e.g., work holder  112  (shown in  FIG.  2   ), as shown with box  310 . A tool assembly, e.g., tooling assembly  110  (shown in  FIG.  2   ) is moved to a turning position, e.g., turning position  260  (shown in  FIG.  10   ), as shown with box  320 . Material is then removed from the workpiece in a turning operation, as shown with box  330 . It is contemplated that the tool assembly can be moved to the turning position in a linear movement, e.g., by displacement of tool platform  264  (shown in  FIG.  7   ), as shown with box  322 . It is also contemplated that the tool assembly can be moved to the turning position using a rotary movement, e.g., using a turret  408  (shown in  FIG.  3   ), as shown with box  324 . 
     Once the turning operation is complete tool assembly is moved to a milling position, as shown with box  340 . Moving the tool assembly from the turning position to the milling can include moving the tool assembly in a linear movement, such as with tool platform  263  (shown in  FIG.  7   ), as shown with box  342 . Moving the tool assembly from the turning position to the milling can include moving the tool assembly in a rotary movement, such as with turret  408  (shown in  FIG.  3   ), as shown with box  344 . Movement to the turning position positions the thread milling tool against the surface of the workpiece for milling threads on the surface of the workpiece, as shown with box  350 . The thread milling then mills threads in the surface of the workpiece in a milling operation, as shown with box  360 . The threads can be milled on an interior surface and/or an exterior surface of the workpiece, as shown with boxes  362  and  364 . 
     It is contemplated that milling threads on the workpiece surface can include rotating the workpiece in concert with a milling tool, e.g., thread milling tool  14  (shown in  FIG.  2   ), as shown with box  370 . The workpiece can be rotated independently of the milling tool, as shown with box  380 . In certain embodiments the workpiece can be turned and milled without removing the workpiece from the work holder, as shown with box  390 . 
     The systems and methods of the present disclosure allow for milling threads on tubular workpieces using a tooling assembly for a CNC threading lathe without generating long cuttings chips or generating obstructions such as “bird nests” while cutting interior or exterior diameters of couplings, pipes and tubes. Such an arrangement allows work that typically requires a lathe, such as edge smoothing, diameter tapering, beveling, and the like, to be performed using the same lathe machine that is used to cut threads on couplings, pipes, tubes, and other workpieces. This one-stop machining process can result in significant savings in time, costs, and complexity, as well as other advantages by virtue of the workpieces being able to remain on the same lathe machine throughout the process until completion. The systems and methods of the present disclosure are particularly applicable to CNC lathe machines that have C-axis control capability, thereby enabling precise and intricate control of the rotation of the workpiece in terms of rotational speed, direction, and degree. Accordingly, the present disclosure greatly improves safety and efficiency of cutting threads on couplings, pipe and tubes. 
     Although the figures depict embodiments of the present disclosure in a particular orientation, it should be understood by those skilled in the art that embodiments of the present disclosure are well suited for use in a variety of orientations. For example, though thread-milling is shown in the illustrated exemplary embodiment on an interior surface of a coupling, it is to be understood and appreciated that threads can also be milled on the exterior surfaces of couplings and/or pipes, as appropriate for an intended application. Further, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. 
     Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. The indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that the particular article introduces; and subsequent use of the definite article “the” is not intended to negate that meaning.