Abstract:
Magnetic table jig assemblies and methods allow workpieces (e.g., aircraft components to be fabricated) on a table top of the table jig assembly to be accurately indexed relative to a robotically operated tool (e.g., a robotically operated drill). The magnetic table jig assembly may include a wheeled frame which is capable of rolling movement across a floor surface, a horizontally planar table top exhibiting ferromagnetic properties supported by the frame and a plurality of magnetic workpiece positioners each including an actuator to magnetically couple and decouple the magnetic workpiece positioner to the table top. The workpiece will therefore be positioning restrained on the table top by magnetically coupling the plurality of the magnetic workpiece positioners to the table top in abutting relationship to a perimetrical edge of the workpiece.

Description:
FIELD 
       [0001]    The embodiments disclosed herein relate generally to the positioning of workpieces on a table jig, especially the positioning of workpieces relative to a robotically operated tool (e.g., a robotically operated drill), such as aircraft structural components. 
       BACKGROUND 
       [0002]    In various branches of the manufacturing industry, during the several stages of production processes, there is a need to handle parts and assemblies until the formation of the final product. The transportation and handling of such parts (components) in each stage depends on the type of process, size of the components, as well as their physical characteristics, such as dimensions, geometry, weight, and fragility. 
         [0003]    During the manufacture of relatively large-sized aircraft structural components, for example, it is necessary to periodically position the component at various stages of the fabrication process to allow for robotically operated tools to act on the component. For example, it may be necessary to position an airfoil structure in operative proximity to a robotically controlled drill to allow for the automated drilling of holes to thereby permit subsequent riveting. It is thus essential that the component be positioned accurately and immovably relative to the robotically operated tool so that the robotic controllers can issue repeatable commands necessary for the tasks to be reliably performed based on the particular component being fabricated. 
         [0004]    Assemblies and methods for the handling, transporting and/or positioning aircraft component parts with the use of jig assemblies is known. In this regard, US Patent Application Publication 2014/0328655 (the entire content of which is expressly incorporated by reference herein) discloses a jig assembly for supporting an aircraft component part. The jig includes an elongate spar assembly, a plurality of rib assemblies attached to the spar, and a plurality of tensionable strap assemblies operatively associated with the rib assemblies for capturing and holding the component part against the rib assemblies. The strap assemblies may include a strap ratchet mechanism and a strap, so that operation of the strap ratchet mechanism allows strap slack to be removed thereby tensioning the strap. The jig assembly may be positioned and oriented by suspension cables and a hoist mechanism to allow it to be removably connected to a moveable transport dolly. 
         [0005]    U.S. Pat. No. 8,661,684 (the entire content of which is expressly incorporated by reference herein) discloses a single piece pulsed flow wing assembly method to provide for the horizontal manufacture of aircraft wings using synchronized automated vehicles guided in a predetermined manner to move and locate wing structures in a plurality of assembly positions. 
         [0006]    While the proposals in the art are satisfactory for their intended purposes, further improvements are desired. For example, it would be especially desirable if a jig could be provided which is capable of universally positioning a variety of different structural components relative to a robotically operated tool with minimal set-up time and/or required layout area. It is towards fulfilling such needs that the embodiments described herein are directed. 
       SUMMARY 
       [0007]    Broadly, the embodiments disclosed herein are directed toward magnetic table jig assemblies and methods whereby workpieces on the table jig assembly may be accurately indexed relative to a robotically operated tool (e.g., a robotically operated drill). According to certain embodiments, a magnetic table jig assembly is provided for positioning a workpiece which includes a wheeled frame which is capable of rolling movement across a floor surface, a horizontally planar table top exhibiting ferromagnetic properties supported by the frame and a plurality of magnetic workpiece positioners each including an actuator to magnetically couple and decouple the magnetic workpiece positioner to the table top. The workpiece will therefore be positioning restrained on the table top by magnetically coupling the plurality of the magnetic workpiece positioners to the table top in abutting relationship to a perimetrical edge of the workpiece. 
         [0008]    In order to establish the indexed position of the table jig assembly relative to a robotically operated tool, a fixed position floor anchor having ferromagnetic properties may be immovably attached to the floor surface. The position of the floor anchor will thereby define the indexed position of the table jig. The table jig assembly may thus be provided with a magnetic table positioner dependently attached to the frame, whereby the magnetic table positioner includes a selector for magnetically coupling and decoupling the table positioner to the fixed- position floor anchor. The table jig assembly is therefore capable of being immovably positioned when the table positioner is magnetically coupled to the floor anchor, but may be rolled across the floor surface when the table positioner is magnetically decoupled from the floor anchor. The floor anchor may include an upright plate having ferromagnetic properties to which the magnetic table positioner may be magnetically coupled and decoupled, and a base plate substantially perpendicular to the upright plate, the base plate being fixed to the floor surface. 
         [0009]    Some embodiments of the table jig assembly will include a plurality of opposed pairs of levelling foot assemblies attached to the frame to allow for levelling of the table top relative to a target horizontal plane. The levelling foot assemblies according to some embodiments may be provided with a threaded shaft having an operator wheel at an upper end thereof and a foot pad at a lower end thereof for engagement with the floor surface, and a threaded collar assembly receiving the threaded shaft. The frame assembly may therefore be raised and lowered depending upon a direction of turning movement applied to the operator wheel to thereby allow levelling of the table top relative to a target horizontal plane. The levelness of the table top may be visually verified by providing opposed pairs of sight level assemblies attached to the frame and positioned at ends of the table assembly to provide a visual indication of table top levelness relative to the target horizontal surface. 
         [0010]    In order to accommodate workpieces of different sizes and/or geometric shapes, the table jig assembly may be provided with a plurality of non-magnetic differently sized and/or shaped spacer blocks. Selected ones of the spacer blocks are thereby positionable in abutting contact between the perimetrical edge of the workpiece and a respective one of the magnetic table positioners. Proper positioning and alignment of the workpiece may also be aided by mutually perpendicular x-axis and y-axis grid lines formed on the table top to provide a mapped reference for placement of workpiece on the table top. 
         [0011]    In use, the workpiece may be oriented relative to a robotically operated tool by immovably positioning the workpiece on the table top relative to x-axis and y-axis grid lines thereon, e.g., by magnetically coupling the plurality of magnetic workpiece positioners to the table top adjacent to a perimetrical edge portion of the workpiece, and moving the table jig into an indexed position relative to the robotically operated tool to allow for operative interaction with the workpiece on the table top. One or more non-magnetic spacers may be positioned between predetermined ones of the magnetic workpiece positioners and the perimetrical edge portion of the workpiece as may be required to accommodate workpieces of virtually any size and/or shape. 
         [0012]    A fixed-position floor anchor may be immovably attached to the floor surface in proximity to the robotically operated tool to thereby define the indexed position of the table jig relative to the robotically operated tool. The table jig assembly may be provided with a magnetic table positioner which can be brought into abutting contact with the floor anchor by movement of the table jig assembly across the floor surface. The operation of a selector of the magnetic table positioner will thereby magnetically couple the magnetic table positioner to the floor anchor whereby the table jig is immovably located at the indexed position (e.g., by selective operation of opposed pairs of levelling feet assemblies operatively associated with the jig assembly frame and visually verifying whether or not the table to is level by means of sight levels). 
         [0013]    These and other aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof. 
     
    
     
       BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS 
         [0014]    The disclosed embodiments of the present invention will be better and more completely understood by referring to the following detailed description of exemplary non-limiting illustrative embodiments in conjunction with the drawings of which: 
           [0015]      FIG. 1  is a perspective view of a universal magnetic table jig assembly in accordance with an embodiment of the invention; 
           [0016]      FIG. 2  is a further perspective view of the universal magnetic table jig assembly with various magnetic positioners and non-magnetic holders that may be employed to universally position a variety of differently sized and/or shaped components on the table top as workpieces; 
           [0017]      FIG. 3  is a side elevational view of the table jig assembly depicted in  FIG. 2 ; 
           [0018]      FIG. 4  is an end elevational view of the table jig assembly depicted in  FIG. 2 ; 
           [0019]      FIG. 5  is a top plan view of the table jig assembly depicted in  FIG. 2 ; 
           [0020]      FIG. 6  is an enlarged perspective detail view of a representative magnetic table positioning assembly for immovably but releasably positioning the table jig assembly relative to a robotically operated tool; 
           [0021]      FIG. 7  is an enlarged detailed perspective view of a representative levelling foot assembly for leveling the table jig assembly; 
           [0022]      FIG. 8  is an enlarged detailed side elevational view of the sight levels employed to ensure that the table top of the table jig assembly is level relative to a target horizontal plane; and 
           [0023]      FIG. 9  is an enlarged perspective detail view showing representative magnetic workpiece positioners and non-magnetic spacers in use for positioning an aircraft structural component as a workpiece on the table top of the table jig assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    Accompanying  FIG. 1  depicts a magnetic table jig assembly  20  positionable relative to a robotically operated tool RT and a conveyance device CD. The robotically operated tool RT may be any type of computer-controlled robotic manipulator and/or assembler. In the environment depicted, the robotically operated tool RT functions to drill aligned holes in the fabrication of an aircraft component AC positioned as a workpiece on the magnetic table assembly  20 . 
         [0025]    The conveyance device CD may be any conventional manually or automatically operated industrial conveyer (e.g., battery-operated conveyer) to move the magnetic table jig assembly  20  between fabrication locations and their associated robotically operated tools RT in the assembly of the aircraft component AC. Thus, whereas one of the robotically operated tools RT at one fabrication location may drill aligned holes in the aircraft component AC, another robotically operated tool RT may serve to insert fasteners/rivets and/or weld components to one another. The conveyance device CD may include a conventional hitch coupler CD h  which cooperates with a correspondingly configured hitch post  22  associated with the table jig assembly  20 . The hitch coupler CD h  may thus be removably coupled to the hitch post  22  so as to allow the table assembly  20  to be conveyed to a different location, e.g., another fabrication station. The table jig assembly  20  will thus be provided with suitable caster wheels  24  attached to the table frame  26  to allow rolling movement along supporting surface of the facility floor FS. The frame  26  may be provided with a grab rail  26   a  at its ends to permit manual movement and/or positioning of the table assembly  20 . 
         [0026]    As is perhaps more clearly depicted in  FIGS. 2-5 , the magnetic table jig assembly  20  includes the table frame  26  which supports an upper horizontally planar table top  28 . The table top  28  is most preferably comprised of or made from a sheet of ferromagnetic material (e.g., steel) to thereby allow the magnetic workpiece positioners (a few of which are depicted in  FIG. 2  by reference numeral  30 ) containing permanent magnets to be magnetically coupled thereto. The table top  28  defines visible grid lines (a few of which are identified in  FIG. 2  by reference numerals  28   x  and  28   y ) along the x and y axes thereof, respectively. 
         [0027]    Although not shown in the drawings, additional indicia may be provided on the table top  28  so as to uniquely identify each location defined by the mutual intersection of the x-axis and y-axis grid lines  28   x ,  28   y,  respectively, to thereby facilitate the pre-planned position of the aircraft component AC on to the table top  28 . The assembly  20  may also be provided with non-magnetic spacers (a few of which are identified in  FIG. 2  by reference numerals  32 ) of various geometric size and shape to be used in combination with the magnetic workpiece positioners  30  as will be discussed in greater detail below. The magnetic workpiece positioners  30  and the non-magnetic spacers  32  may be kept in close proximity to the table  28  within the end storage drawers  28   a.    
         [0028]    The frame  26  supports dependent magnetic frame positioner assemblies  34  for immovably but releasably positioning the table jig  20  relative to the robotically operated tool RT. As is perhaps more clearly depicted in the enlarged view of  FIG. 6 , the magnetic table positioner assemblies  34  include a post  34   a  rigidly affixed at its upper end to the table frame  26  and carrying a support platform  34   b  rigidly affixed to its lower end. The support platform  34   b  carries a magnetic table positioner  36  which is capable of being magnetically coupled and uncoupled to a fixed-position floor anchor  40 . The floor anchors  40  provide fixed index references for the table top  28  that may be used by the controller for the robotically operated tool RT. 
         [0029]    The floor anchor  40  may be in the form of an L-shaped structure as shown having a vertically upright plate  40   a  and a base plate  40   b  formed at a right angle thereto. An angle brace  40   c  extends between and rigidly braces the upright plate  40   a  to the base plate  40   b.  The base plate is immovably fixed to the facility floor FS by means of suitable bolts  40   d.  At least the upright plate  40   a  of the anchor  40 , and typically the entirety of the anchor  40 , is formed of a ferromagnetic material (e.g., steel). 
         [0030]    The magnetic table positioner  36  is in and of itself conventional in that an internal permanent magnet is provided that may be turned (rotated) by the selector  36   a  so as to bring the permanent magnet into and out of magnetic coupling with the upright plate  40   a.  Thus, when the selector  36   a  is turned so as to magnetically couple the positioner  36  to the upright plate  40   a,  the table assembly  20  will be immovably locked at a predefined position relative to the robotically operated tool RT. In such a manner therefore, the x-axis and y-axis grid lines  28   x  and  28   y  will thus in turn be in a predefined position relative to the robotically operated tool RT. 
         [0031]    In order to ensure proper leveling of the table top  28 , the frame  26  also carries opposed pairs of levelling foot assemblies  44 . A representative levelling foot assembly is depicted in greater detail by  FIG. 7 . As shown, the levelling foot assembly  44  includes a threaded shaft  44   a  which is vertically supported by a threaded collar assembly  46  attached to the frame  26 . The lower end of the shaft  44   a  is provided with a planar foot pad  44   b  while the upper end of the shaft  44   a  is connected to an operator wheel  44   c.  Manual turning movement applied to the operator wheel  44   c  will therefore be translated into lowering or raising of the foot pad  44   b  relative to the frame assembly  26  (i.e., dependent upon whether the shaft  44   a  is turned by the operator wheel  44   c  in either a clockwise or counterclockwise direction, respectively). When in contact with the facility floor FS, therefore, turning the operator wheel  44   c  in either a clockwise or counterclockwise direction will respectively translate into slight (but meaningful) adjustments being made to the table top  28  by virtue of the frame  26  being slightly (but meaningfully) raised and lowered. 
         [0032]    Opposed pairs of sight level assemblies  50  are positioned near each end of the table assembly  20  so as to allow for a visual indication of the table levelness relative to a target horizontal plane that is obtained by coordinated manipulation of the levelling foot assemblies  40  in the manner described above. The sight level assemblies  50  include conventional sight bubble indicators  50   a,    50   b  oriented parallel and perpendicular to the target horizontal plane. When each of the sight bubbles of each of the sight level assemblies  50  is positioned at its centered location, the operator will then know that the table  28  is itself positioned so as to be level with respect to the target horizontal plane. 
         [0033]    In use, table assembly  20  is manipulated into position so as to bring the magnetic table positioners  36  into adjacent face-to-face contact with the vertical plates  40   a  of the floor anchors  40 . The table top  28  may be levelled by the coordinated manipulation of the levelling foot assemblies  44 , the levelness of the table top  28  being assured by the visual indication provided by means of the sight level assemblies  50 . With the table top  28  level, the selector  36   a  of the magnetic positioners  36  may be operated so as to cause the magnetic positioner to be magnetically coupled to the upright plate  40   a  of the floor anchor  40 . Once the table assembly  20  has been magnetically coupled to the floor anchors  40 , the table assembly  20 , and hence the table top  28 , will be properly indexed relative to the robotically operated tool RT. As such, the programmatic controller for the tool RT will then be capable of using the floor anchors  40  as fixed indexes for the table top  28 . 
         [0034]    The aircraft component AC may be placed onto the table top  28  in a pre-planned location either before or after the positioning of the table assembly  20  relative to the robotically operated tool RT. In either situation, the x-axis and y-axis grid lines provide a map reference for the proper positioning of the aircraft component AC onto the table top  28  in its pre-planned position. 
         [0035]    Once the aircraft component AC has been placed onto the table top  28  in its pre-planned location, the magnetic workpiece positioners  30  and/or the non-magnetic spacers  32  may be placed into abutting contact at perimetrical edge regions of the aircraft component AC. As is perhaps better shown by  FIG. 9 , the spacers  32  allow for a transition between, e.g., a leading edge of the aircraft component AC and an individual one of the magnetic workpiece positioners  30  thereby protecting the leading edge of the aircraft component AC from damage. Once the desired number of magnetic workpiece positioners  30  and/or non-magnetic spacers  32  have been placed onto the table top  28  in abutting contact with the perimetrical edge regions of the aircraft component AC, the actuators  30   a  of each positioner  30  may be turned so as to cause the associated positioner  30  to be magnetically coupled to the table top  28 . In this regard, like the table positioner  36  described previously in relation to  FIG. 6 , each of the associated workpiece positioners  30  is in and of itself conventional in that it contains a permanent magnet (not shown) that may be rotated within the positioner  30  by means of the actuator  30   a  so as to cause the permanent magnet to be magnetically coupled and decoupled relative to the table top  28 . 
         [0036]    With all of the workpiece positioners  30  actuated so as to be magnetically coupled to the table top  28 , the robotically operated tool RT may then be activated so it performs the desired automated tool operations. When the robotically operated tool RT is finished, the table assembly may be magnetically uncoupled from the floor anchors  40  (i.e. by movement of the selector  36   a  as described previously) so that the conveyance device may be connected to the hitch post  22  to allow the table assembly  20  (and the aircraft component AC thereon) to be transported to another downstream processing location. When all manufacturing processes have been completed, the aircraft component AC may be removed from the table top  28  by movement of the actuators  30   a  so as to magnetically uncouple the positioners  30  from the table top  28 . The positioners  30  and spacers  32  may then be stored within the drawers  28   a  until next required for another similar to different aircraft component AC. 
         [0037]    The invention herein is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.