Abstract:
The present invention is directed to an apparatus for receiving a cylindrical workpiece and centering that workpiece on a central axis of an elongated support frame. An overhanging machine slides along parallel rails spaced equidistantly from the central axis and enables a machine bit aligned with the central axis to contact the cylindrical workpiece at points located precisely along its apex. Because the machine is moveable relative to the stationary workpiece, the apparatus eliminates a need complex fixturing and increases throughput while enabling repeated accurate alignment of a moving machine bit with the apex of the cylindrical workpiece centered on and lying along the central axis.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a machining apparatus and more specifically to a sliding press for milling, drilling, reaming and routing a cylindrical workpiece along its longitudinal axis and with zero degrees of lateral deflection from the longitudinal axis of the workpiece. 
         [0003]    2. Discussion of Background Information 
         [0004]    Drilling, milling, or routing material from a long cylindrical workpiece, such as a heavy steel pipe or PVC tubing, can be expensive and time consuming. Achieving a high degree of accuracy with regard to aligning a moving machine bit with one or more targets on a cylindrical workpiece presents a substantial challenge and typically requires orienting and affixing a workpiece to a machine table prior to each operation. 
         [0005]    For example, drilling holes in a long, heavy pipe cylindrical pipe presents one such challenge. Typically, a machinist must affix the workpiece to a standing drill press table so that the drill bit aligns perfectly with the pipe surface at a desired location. This may require measuring along the length and diameter of the pipe to determine the desired drilling location, pre-scoring the target with a center punch, and then eyeballing the alignment of the drill bit with the target. Depending on the length and flexibility of the pipe, a machinist may need to align additional support fixtures to balance the length of the pipe and maintain the drilling surface in alignment with the drill press table. Once the target is aligned and a hole is drilled, the machinist must then release the pipe from the work table, locate and center punch the next desired drilling location, and then reorient and re-affix the pipe and additional support fixtures. These repetitive steps reduce efficiency and increase opportunities for error with regard to alignment of each hole with a desired location and/or alignment of each hole relative to one or more other drilled holes positioned along the surface of the cylindrical workpiece. 
         [0006]    For improved accuracy, a machinist may prefer to machine a cylindrical workpiece using a computer numerical controlled (CNC) machine. CNC machines are highly accurate and efficient but are relatively expensive to procure and operate, as compared to a standard drill press or milling machine. CNC machines also require an elevated level of skill for pre-programming the desired machine path along the length of a workpiece. 
         [0007]    Most apparatuses for machining long cylindrical workpieces are stationary devices incapable of portability. Typically, drill presses and CNC machines are affixed to flooring and/or are too cumbersome to port. Furthermore, existing apparatuses for machining cylindrical workpieces typically provide no mechanism for automatically centering the workpiece beneath a bit. Furthermore, some apparatuses with moving machinery thereon enable movement of the machinery in two axes, allowing for increased bi-lateral slippage and deviation from exact alignment of the machine bit from a target location. 
         [0008]    All of these existing methods are inaccurate, time consuming, cumbersome, and/or costly. A need therefore exists for a portable and efficient assembly that enables a machine to move in one direction along the length of a cylindrical workpiece to accurately place machined holes and slots with maximum efficiency. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention solves the problems associated with drilling, milling, reaming and routing material from a cylindrical workpiece and provides an apparatus for efficiently and repeatedly positioning a machining device at the apex of a stationary cylindrical workpiece. The apparatus comprises a trough shaped support frame and at least one cradle thereon wherein the longitudinal axis of the support frame aligns with the longitudinal axis of the at least one cradle. The at least one cradle is adapted to receive thereon a cylindrical workpiece, and the at least one cradle is shaped and positioned so as to automatically align the longitudinal axis of the cylindrical workpiece with the longitudinal axis of the support frame. 
         [0010]    The apparatus further comprises a pair of parallel rails affixed to the sidewalls of the trough shaped support frame, and the parallel rails also extend parallel to and equidistantly from the longitudinal axis of the support frame. A symmetrically shaped concave arcuate support member extends between the pair of parallel rails, terminating in a rail bearing means on each end for slidably engaging each respective rail. The support member is adapted to receive a machine thereon having a rotating bit centered at the apex of the support member and aligned with the longitudinal axes of the support frame, the cylindrical workpiece, and the at least one cradle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    One will better understand these and other features, aspects, and advantages of the present invention following a review of the description, appended claims, and accompanying drawings: 
           [0012]      FIG. 1  depicts a cross-sectional end view of one embodiment of the apparatus of the present invention. 
           [0013]      FIG. 2  depicts a perspective view of one embodiment of a portion of the apparatus of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    The present invention solves the problems associated with drilling, milling, reaming, routing, etc. a long cylindrical workpiece, such as steel tubing or PVC pipe. In particular the present invention addresses inefficiencies and inconveniences associated with fixture clamping and accurately machining such long, cumbersome cylindrical workpieces. Although the apparatus of the present invention may employ any number of machines thereon, for purposes of simplicity, the following detailed description will refer to a drill press for drilling holes in a cylindrical pipe. 
         [0015]      FIGS. 1 and 2  depict one embodiment of the apparatus  100  of the present invention for positioning a machining device at the apex of a stationary cylindrical workpiece. The apparatus  100  comprises a support frame  200  having a symmetrical cross section and a longitudinal central axis  205  along which one or more cradles  210  are disposed. The one or more cradles  210  are centered in exact alignment with the central axis  205  of the support frame  200 . In the embodiment depicted in  FIGS. 1 and 2 , the support frame  200  is trough shaped with a horizontally oriented flat bottom  215  and two sidewalls  220  rising perpendicularly therefrom. The bottom  215  and sidewalls  220  catch and entrap all material cast off during machining operations, such as metal shavings created while drilling holes in a steel pipe. 
         [0016]    The support frame  200  may take any number of alternate shapes. For example, the sidewalls  220  might rise at an angle from the bottom  215  rather than rising perpendicularly from that surface. The sidewalls  220  thus may be angled inward or outward, toward or away from the central axis  205  as long as they remain equidistant from the central axis  205 . In another embodiment, the bottom  215  of the support frame may have a V-shaped cross section so that the apex of the “V” aligns with the central axis  205  and the wings of the “V” are sloped inward at the same angle. In this way, a pipe  400  placed in the support frame  200  will roll to the central axis  205  and settle thereon, perfectly constrained about the central axis by the sloping wings of the V-shaped bottom  215 . This embodiment would eliminate the need for one or more separately applied cradles  210  because the entire length of the support frame  200  would serve to cradle and support a lengthy pipe  400 . Another embodiment (not shown) may employ a support frame  200  having a bottom  215  and open sides bounded by railing-like elements anchored to the ends of the support frame  200  and spanning the length of the support frame  200  parallel to the central axis  205 . Again, the as long as the railing-like elements remain equidistant from the central axis  205  and parallel to the central axis  205 , the apparatus  100  of the present invention will function as designed to maintain proper alignment between critical elements as herein further described. 
         [0017]    As shown in the embodiment of  FIGS. 1 and 2 , the support frame  200  comprises a plurality of cradles  210  disposed thereon at even increments to provide balanced support along the length of a pipe  400 . In an alternate embodiment, the cradles  210  may lie at uneven increments to provide more support in particular locations. For example, some portion of the cradles  210  may bunch together towards the ends of the support frame  200  to support a pipe having thicker, heavier walls or heavy transition elements at either or both ends. In yet another embodiment, the cradle  210  may be one long cradle  210  disposed on the support frame  200  for supporting the pipe  400  thereon and aligning the longitudinal pipe axis  405  with the central axis  205 . 
         [0018]    Returning now to the embodiment of  FIGS. 1 and 2 , the one or more cradles  210  are substantially V-shaped, with opposing wings  212  sloping downward toward the central axis  205 . The opposing wings  212  are equidistant from the central axis  205  and are sloped at the same angle θ from horizontal  214 . In a preferred embodiment, the opposing wings  212  are angled between 20 and 80 degrees from horizontal  214  and more particularly at 45 degrees from horizontal. In some embodiments, the slope of the wings  212  may be adjustable to accommodate pipes  400  having large diameters overall or at certain locations along their lengths. In other embodiments, the wings  212  may be adjustable so that they extend further upward but at a steady angle from horizontal  214 . The angle θ of the wings  212  is variable as long as the wings  212  of each individual cradle  210  are spaced equidistantly form the central axis  205  and are positioned at the same angle θ from horizontal  214 . The one or more cradles  210  therefore automatically center the pipe  400  therein by design. Gravity and the angled, equidistantly spaced wings  212  center the pipe  405  around the central axis  205  so that the longitudinal pipe axis  405  is parallel to the central axis  205  of the support frame  200 . 
         [0019]    In certain embodiments the one or more cradles  210  are affixed to the support frame  200  so as to prevent any movement and so as to withstand forces applied while machining a pipe  400  positioned in the one or more cradles. For example, in certain embodiments, the one or more cradles  210  may be bolted or welded to the bottom  215  of the support frame  200 . In other embodiments, the one or more cradles  210  may be selectively secured with set screws or magnets, for example. Allowing selective locking enables a machinist to space the one or more cradles  210  in any configuration along the central axis  205  and thereby provide additional support along certain portions of a length of pipe  400 . 
         [0020]    In the embodiment of  FIGS. 1 and 2 , the wings  212  of the cradles  210  are substantially flat faced elements. In other embodiments, the wings  212  may comprise surface topography for increasing friction between the wings  212  and a pipe  400  thereon during machining operations. Such topography assists with reducing any movement caused by vibrations and thereby reduces the likelihood that the moving machine bit would wander from the desired target on the pipe  400 . The faces of the wings  212  may be peened, sandblasted, coated with grit, or etched, for example, as long as the faces are treated equally and to the same degree so that the outermost surface layers of the wings  212  of a cradle  210  remain equidistant from the central axis  205  at every matching point along their lengths. This ensures that a pipe  400  thereon will be perfectly centered on the central axis  205  so that the longitudinal pipe axis  405  aligns with and lies parallel to the central axis  205 . 
         [0021]    In addition to providing secure seating during machining operations to counteract any torsional and vibration forces, certain embodiments of the one or more cradles  210  allow for drilling through the entire pipe so that both the upper apex and lower apex are drilled. The embodiment of  FIGS. 1 and 2  allows for such an operation. As  FIG. 1  clearly depicts, the wings  212  of the one or more cradles  210  have a gap  225  between them at their lower edges. This gap  225  allows for through hole drilling of the wall of the pipe  400  at the lower apex. In the embodiment depicted in  FIG. 1 , the substantially flat wings  212  of the cradle  210  are raised above the bottom  215  of the support frame  200  by a pair of risers  230 . The pair of risers  230  may be integrally formed with the wings  212  or permanently secured thereto through some affixing means such as welding, bolting, epoxy bonding, etc. In any case, the risers  230  are identically shaped so that the wings  212  remain at a constant angle θ from horizontal  214  and so that the wings  212  are equidistant from the central axis  205  at all mirrored points along their lengths. The gap  230  is further created by the wings  212  themselves which comprise a thickness T that further elevates their pipe contact surfaces from the bottom  215  of the support frame  200 . 
         [0022]    In addition to a support frame  200  having one or more cradles  210  disposed thereon, the apparatus  100  of present invention further comprises a support member  300  adapted for receiving a machine  305  thereon, such as a Rigid® HC-300 drill press. In the embodiment depicted in  FIG. 1 , the drill press  305  is mounted and secured to the support member  300  so that the machine bit  310  aligns with the central axis  205  of the support frame and therefore also aligns with the longitudinal pipe axis  405 . The support member  305  is an arcuate member disposed above the one or more cradles  210  and symmetrically curved about the central axis  205 . In the embodiment of  FIG. 1 , the arcuate support member  305  is oriented concave down so that any forces applied during machining are counteracted by the radial compression strength of the arcuate support member  305 . The drill press  305  is centered on the support member apex  315  so that the support member apex  315 , the machine bit  310 , the longitudinal pipe axis  405  and the central axis  205  are all in parallel alignment. 
         [0023]    The support member  300  may be fabricated from any stiff, strong material capable of withstanding torsional and linear forces applied during machining operations so that the moving bit never deviates from alignment with a target on the apex of the pipe  400 . For example, in one embodiment, the support member  300  may be formed from a bent strip of 1.5 inch wide and 0.5 inch thick angle iron. Bending deforms the strip of angle iron and induces internal stresses, but no deformation occurs beyond the yield strength of the crystalline structure. Instead, bending a strip of material to form the arcuate support member  300  creates compression forces in the lower surface and tension forces in the upper surface of the support member  300 . These inherent forces resist forces generated by the drill press  305  during machining operations. 
         [0024]    In addition to having an arcuate curvature, the support member  305  slidably mounts to the support frame  200  for movement in the direction of the longitudinal axis only. In the embodiment of  FIG. 1 , the support member  300  terminates at each end in a flange  320 . Each flanged end  320  of the support member  300  is rigidly affixed to support plates  325  that are bound to bearing members  330 . In some embodiments, the support member  305  comprises a single strip of bent stock. In other embodiments, the support member may comprise more than one strip of bent stock, in which embodiments, additional bearing members  330  and support plates  325  would be incorporated accordingly. Adding additional support members  300  beneath the drill press  305  would increase stability to prevent any deflection of the moving bit  310 . 
         [0025]    Returning to the embodiment of  FIG. 1 , the bearing members  330  are linear bearings slidably engaged with a pair of parallel rails  235  that are respectively mounted along the opposing sidewalls  225  of the support frame  200 . The parallel rails are affixed to the sidewalls  225  through some mechanical means such as but not limited to welding, screwing, clamping, nailing, riveting, and gluing. The rails  225  are positioned at even heights from the bottom  210  of the support frame  200  and at even distances from the central axis  205 . This ensures that the arcuate support member  300  is centered on the central axis  205 . Because the sidewalls and rails  235  are equidistant from the central axis  205 , the bit  310  remains perfectly aligned with the longitudinal pipe axis  405  as the support member  305  slides along the rails  235 . 
         [0026]    The pair of rails  235  may be made of any round stock and preferably from a polished stock that allows for smooth movement of the bearing members  330 . For example, in the embodiment depicted in  FIG. 2 , the pair of parallel rails  235  are 24 foot lengths of 1.25 inch diameter polished round stock. The pair of rails  235  extend beyond the ends of the support frame  200  so that the drill press  305  may slide out of the path of a pipe  400  during loading and unloading onto the apparatus  100 . The apparatus  100  further comprises cross members  240  attached to the pair of parallel rails  235  to prevent the support member  300  from sliding past the ends of the rails  235  and disengaging from the apparatus  100 . In some embodiments, the apparatus  100  may further comprise a braking system for halting travel of the support member  305  during drilling. This further adds to the stability of drilling a hole at a target location with zero deviation. The rails system therefore constrains travel of the support member  300  to longitudinal motion with no lateral movement. This configuration insures zero deviation of the moving drill  310  from the drill target on the apex of the pipe  400 . 
         [0027]    Because the drill press  305  moves relative to a stationary pipe  400  therebeneath, and because the drill bit  310  and target locations on the apex of the pipe  400  are automatically precisely aligned by virtue of the pipe  400  resting in the one or more cradles  210 , the apparatus  100  enables efficient and accurate drilling at points along a linear path at the apex of the stationary pipe  400 . In one trial, the apparatus  100  averaged a 1.8 minute per hole drill time whereas a standard drill press averaged 4.03 minutes per hole. This trial demonstrated that the apparatus  100  of the present invention provides a 55% increase in efficiency over standard drilling methods. 
         [0028]    In addition to providing increased efficiency, the present invention also provides improvements in ergonomics and portability. Because the apparatus  100  eliminates a need for affixing, releasing, repositioning and re-affixing a pipe to a fixture or drill press table between operations, a machinist need not wrestle with positioning a heavy length of pipe repeatedly. Instead, a machinist using the present invention may employ ergonomic cranes to lift a heavy pipe onto the apparatus  100  just one time. The sliding support member  300  moves relative to the stationary pipe  400  which is precisely positioned therebeneath without any extensive measurement or fixture jigs required for proper alignment. 
         [0029]    In some embodiments, the apparatus  100  comprises legs  500  extending from the underside of the support frame  200  and terminating in wheels  505  which may be locking and/or swivel wheels. This configuration enables a machinist to easily move the apparatus  100  to a convenient location for machining a workpiece and prevents the machinist from having to lug heavy pipes  400  from remote locations to a stationary apparatus  100 . This greatly reduces travel time and stress related injuries associated with lifting and repositioning heavy pipes. In some embodiments, the legs  500  may extend upward and downward to facilitate loading and unloading a heavy pipe  400  with easy and to enable an operator raise the loaded apparatus  100  to a comfortable, ergonomic working height. 
         [0030]    The apparatus  100  comprises elements constructed easily from simple materials. For example, the support frame  200  may be manufacture from conveniently procured and low cost rigid materials such as but not limited to wood, cement, metal, plastic and rubber. The bottom  215  and sidewalls  220  may be welded together, bolted, glued, or riveted for example, or the entire support frame  200  may be manufactured as an integrated unit. For example, the support frame  200  may be extruded, heat formed, molded or cast to take its final shape. Similarly, the one or more cradles  210  may be manufactured from conveniently procured and low cost rigid materials such as but not limited to wood, cement, metal, plastic and rubber. Preferably, the elements of the apparatus  100  will be manufactured from materials capable of achieving a high tolerance and using exacting methods of manufacture so that the central axis  205  aligns perfectly with the apex  315  of the support member  300 , the drill bit  310  and the longitudinal axis  405  of the pipe  400  seated in the one or more cradles  210 . 
         [0031]    Because the apparatus  100  comprises standard materials and few moving parts, the overall cost of manufacture is relatively low compared to a standard drill press or CNC machine, for example. Furthermore, the apparatus  100  requires no extensive training to operate and the only consumables associated with the present invention are electricity for powering the drill press  305  and any lubricant applied to the moving drill bit  310 . Therefore, in addition to being ergonomic and portable, the apparatus  100  of the present invention enables reliable and efficient operations at relatively low cost. 
         [0032]    It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words, which have been used herein, are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.