Abstract:
A method and apparatus for providing motor vehicle sub-assemblies with unrestricted model mix and quick changeover between models. The apparatus includes a track; a carriage mounted for longitudinal movement along the track between first and second positions; and first and second turrets rotatably mounted on the carriage at longitudinally spaced locations and each including a plurality of circumferentially spaced individual faces and unique tooling fixtures on the respective faces for receiving unique work piece components corresponding to a plurality of motor vehicle body styles.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of U.S. Provisional Patent Application Ser. No. 60/849,241 filed on Oct. 4, 2006, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a motor vehicle body assembly, and more particularly to the formation and welding of motor vehicle body sub-assemblies with unrestricted model mix and quick changeover between models. 
     BACKGROUND OF THE INVENTION 
     A typical motor vehicle assembly plan is set up to produce several different body styles or models on the same assembly line. Each body style requires unique sub-assemblies and each sub-assembly requires unique end effector tooling. In the prior art, in order to change end effector tooling to effect a body style changeover at a sub-assembly location from a first model to a second model, robots are utilized to move the end effecter tooling corresponding to the first model from the sub-assembly location to a suitable storage location, all of the energy feeds for the tooling are decoupled, the robot picks up new tooling corresponding to the second model, the energy feeds of the new tooling are coupled to the robot, and the robot moves the new tooling to the sub-assembly location. This entire procedure is time consuming and inefficient especially in a random model mix assembly plant where the body style is frequently changed. 
     SUMMARY OF THE INVENTION 
     This invention is directed to the provision of a method and apparatus for providing motor vehicle sub-assemblies for a plurality of motor vehicle models with unrestricted model mix and quick changeover between models. 
     According to an important feature of the invention apparatus, the apparatus includes a turret having a central axis and first and second tooling faces spaced circumferentially about the central axis; unique tooling fixtures on the respective first and second faces for receiving unique work piece components corresponding respectively to the first and second motor vehicle body styles; and mounting structure mounting the turret for movement along a linear path between first and second work stations and for rotation about its central axis to selectively present a respective face and its unique tooling to a work station for receipt of unique work piece components corresponding to a respective motor vehicle body style. 
     According to a further feature of the invention apparatus, the first work station is defined on one side of the path; the second work station is defined on an opposite side of the path; and the apparatus further includes means operative to rotate the turret through 180° as the turret moves between the first and second work stations whereby to move a tooling face from a position presenting on one side of the path at the first work station to a position presenting on an opposite side of the path at the second work station. In one disclosed embodiment of the invention, the first work station comprises a loading station and the second work station comprises a welding station. 
     According to a further feature of the invention apparatus, the mounting structure includes a track, a carriage mounted for linear movement along the track, and journal structure on the carriage mounting the turret on the carriage for rotation about its central axis. 
     According to a further feature of the invention apparatus, the turret comprises a first turret and the apparatus further includes a second turret rotatably mounted on the carriage in longitudinally spaced relation to the first turret and including first and second tooling faces spaced circumferentially with respect to the rotational axis of the second turret and unique tooling fixtures on the respective first and second tooling faces of the second turret for receiving unique work piece components corresponding respectively to the first and second motor vehicle body style. 
     According to a further feature of the invention apparatus, the apparatus further includes power means operative to rotate each turret through 180° as the carriage is moved from its first position to its second position. 
     According to a further feature of the invention apparatus, the power means comprises a carriage motor assembly operative to move the carriage along the path between the first and second positions and turret motor assemblies mounted on the carriage and operative to rotate the turrets on the carriage. 
     According to a further feature of the invention apparatus, each turret includes a tower structure defining the first and second faces and a base ring gear positioned on the carriage and each turret motor assembly includes a motor driving a pinion engaging the ring gear of the respective turret. 
     According to a further feature of the invention apparatus, the track includes a plurality of longitudinally spaced rollers; the carriage is rollably mounted on the rollers; and the carriage motor assembly includes a motor driving the rollers whereby to propel the carriage along the track. 
     According to a further feature of the invention apparatus, the apparatus further includes a latch assembly mounted on the carriage and operative to selectively preclude sliding movement of the carriage along the track and rotation of the turrets on the carriage. 
     According to an important feature of the invention methodology, a turret is provided having a central axis and first and second tooling faces spaced circumferentially about the central axis; unique tooling fixtures are provided on the respective first and second faces for receiving unique work piece components corresponding respectively to first and second motor vehicle body styles; the turret is moved along a linear path between first and second work stations; and the turret is rotated about its central axis to selectively present a respective face and its unique tooling to a work station for receipt of unique work piece components corresponding to a respective motor vehicle body style. 
     According to a further feature of the invention methodology, the first work station is defined on one side of the path; the second work station is defined on an opposite side of the path; and the turret is rotated 180° as the turret moves between the first and second work stations whereby to move a tooling face from a position presenting on one side of the path at the first work station to a position presenting on an opposite side of the path at the second work station. 
     According to a further feature of the invention methodology, a track is provided extending between the first and second work station; a carriage is provided mounted for linear movement along the track; and journal means are provided on the carriage mounting the turret on the carriage for rotation about its central axis. 
     According to a further feature of the invention methodology, the turret comprises a first turret and the method includes the further steps of providing a second turret rotatably mounted on the carriage in longitudinally spaced relation to the first turret and including first and second tooling faces spaced circumferentially with respect to the rotational axis of the second turret and unique tooling fixtures on the respective first and second tooling faces of the second turret for receiving unique work piece components corresponding respectively to the first and second motor vehicle body style. 
     According to a further feature of the invention methodology, a path is provided having a load side and an unload side; a carriage is provided mounted for longitudinal movement along the path between a first position and a second position; first and second turrets are provided rotatably mounted on the carriage at longitudinally spaced locations on the carriage; first and second circumferentially spaced individual tooling faces are provided on each turret; unique tooling fixtures are provided on the respective first and second turret tooling faces for receiving unique work piece components corresponding to first and second motor vehicle body styles; the carriage is positioned in its first position with the first turret positioned with a first face thereof facing the load side of the path and the second turret positioned with the first face thereof facing the unload side of the path and work piece components corresponding to the first motor vehicle body style positioned on the first face thereof; work piece components corresponding to the first motor vehicle body style are loaded onto the tooling fixtures on the first side of the first turret while welding the work piece components corresponding to the first motor vehicle body style positioned on the first side of the second turret and thereafter removing the welded together work piece components from the second turret for further processing; and the carriage is thereafter moved to its second position while rotating the first turret to position the first face thereof facing the unload side of the path and rotating the second turret to position the first face thereof facing the load side of the path. 
     According to a further feature of the invention methodology, the method includes the further steps of, with the carriage in its second position, loading work piece components corresponding to the first motor vehicle body style onto the tooling fixtures on the first face of the second turret while welding the work piece components corresponding to the first motor vehicle body style positioned on the first face of the first turret and thereafter removing the welded together work piece components from the first turret for further processing. 
     According to a further feature of the invention methodology, the invention includes the further steps of, when a changeover to the second motor vehicle body style is required, rotating the first and second turrets to bring the second face of each carriage into the position corresponding to the position of the first face prior to the changeover. 
     According to a further feature of the invention methodology, each turret includes a third face circumferentially spaced from the first and second faces and unique tooling fixtures corresponding to a third motor vehicle body style are positioned on the third faces of the turrets whereby to allow changeover between the first and third body styles and the second and third body styles in addition to the changeover between the first and second body styles. 
     According to a further feature of the invention methodology, each turret further includes a fourth face circumferentially spaced from the first, second and third faces and unique tooling fixtures corresponding to a fourth motor vehicle body style are positioned on the fourth faces of the turrets whereby to allow changeover between the first and fourth body styles, the second and fourth body styles and the third and fourth body styles in addition to the changeovers between the first and second body styles, the first and third body styles and the second and third body styles. 
     Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  is a schematic plan view of an automotive body assembly installation including an automotive body subassembly apparatus according to the invention; 
         FIG. 2  is a perspective view of the automotive body subassembly apparatus; 
         FIG. 3  is a fragmentary detail view of a power roll assembly utilized in the body subassembly apparatus; 
         FIG. 4  is a perspective view of a shuttle assembly utilized in the body subassembly apparatus; 
         FIGS. 5 and 6  are detail views of a latch mechanism utilized in the shuttle assembly; 
         FIG. 7  is an exploded perspective view showing a carriage and a track structure utilized in the body subassembly apparatus; 
         FIG. 8  is a perspective view of a roller turret guide assembly; and 
         FIG. 9  is a cross-sectional view of the power roll assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The automobile body assembly installation seen in  FIG. 1  is especially suited for use in fabricating automotive sub-assemblies such as doors, hoods, deck lids, cowls, etc. 
     An important part of the installation of  FIG. 1  comprises an automotive body subassembly apparatus  10 , two of which are seen in  FIG. 1 . 
     Each body subassembly apparatus  10 , broadly considered, includes a track structure  12  and a shuttle assembly  14 . 
     Track structure  12  includes a plurality of transverse longitudinally spaced cross members  16  supported at their opposite ends by foot pads  18  suitably secured to a floor surface  20 ; a central longitudinal spine member  22  interconnecting the cross members, a pair of tubular rail members  24  extending along opposite end edges of the cross members; and a power roll assembly  26 . 
     Power roll assembly  26  includes a plurality of rollers  28 , a plurality of drive elements  30 , and a motor assembly  32 . 
     Each roller  28  is journaled within a respective rail member  24  by a shaft  34  with an upper portion of the roller projecting through a window  24   a  in the rail member to position the upper peripheral face  28   a  of the roller above the upper face of the rail member. A series of rollers  28  are positioned in longitudinally spaced relation in each rail member  24 . 
     Drive elements  30  may comprise belts or chains driving the rollers  28  via pulleys or sprockets  36  fixedly secured on the respective shafts  34 . 
     Motor assembly  32  includes an electric motor  38  driving an output shaft  40  through a reduction gear mechanism  42 . Shaft  40  extends through rail members  24 , terminates in free end  40   a , and serves to drive a central roller  28  in each of the series of the rollers in the respective rail members, whereby powered rotation of shaft  40  acts via drive elements  30  to rotate all of the rollers in both rail members in a direction corresponding to the direction of rotation of shaft  40 . 
     Shuttle assembly  14  includes a pallet or carriage  46 , a pair of turrets  48 , a pair of turret motor assemblies  50 , and a latch assembly  52 . 
     Carriage  46  is sized to slide along track structure  12  on rollers  28  so as to effectively shuttle back and forth along the track structure. 
     Carriage  46  includes a pair of tubular rail members  54 , laterally spaced by a distance corresponding to the lateral spacing of the rail members  24  so as to enable the rail members  54  to move rollably along the rollers  28  in the respective rail members  24 ; end cross members  56 ; central cross members  58 ; intermediate cross members  60 ; X structures  62  positioned between each respective set of end members  56  and intermediate members  60 ; turret roller guide structures  64 ; a guide plate  66  underlying central cross members  58 ; a motor mount structure  68  positioned centrally on each end cross member  56 ; and a latch guide structure  70  centrally positioned on each intermediate cross member  60 . 
     Each roller guide structure  64  includes a base plate  64   a , spaced upstanding lugs  64   b , and a roller  72  journaled between the spaced lugs. A roller guide structure  64  is fixedly positioned on each distal end of each X structure  62  at the intersections of the guide rails  54 , end rails  56 , and intermediate rails  60  with the rotational axes of the rollers  72  on each X structure  62  intersecting at the center  62   a  of the X structure. 
     Each motor mount structure  68  includes a plurality of stacked plates including an upper lug plate  68   a.    
     Each latch guide structure  70  includes a base portion  70   a  secured to a respective intermediate cross-member  60  and a pair of spaced lugs  70   b.    
     Each turret  48  includes a base ring gear  74  and a tower structure  76  fixedly secured to an upper face of the ring gear. 
     Tower structure  76  has a truncated pyramidal configuration and includes an upper rectangular frame structure  76   a , a lower lattice work base structure  76   b , and a plurality of inwardly angled upstanding members  76   c  extending between the base structure  76   b  and the upper frame structure  76   a . The described structure will be seen to define four upwardly angled rectangular turret faces A, B, C and D, with each face defined between a pair of spaced upright members  76   c.    
     Each turret is mounted at the center  62   a  of a respective X structure  62  via a suitable bearing structure  80  journaling a central hub portion  74   a  of the respective ring gear with the underface of the rim  74   b  of the ring gear rollably guiding on the rollers  72  of the respective turret guide structures  64  whereby to allow free rotation of the turret on the carriage about the axis of the bearing  80 . 
     Each turret motor assembly  50  comprises an electric motor  82 , a reduction gearing  84 , an output shaft  86 , and a pinion gear  88  driven by the output shaft. The motor  50  is mounted on the end of a guide rail  54  with the reduction gearing  84  mounted beneath a respective lug plate  68   a  with the output shaft extending upwardly thorough the lug plate to position the pinion gear  88  above the lug plate face in meshing engagement with the gear teeth  76   c  of the respective ring gear of the respective turret whereby actuation of the motor  50  has the effect of rotating the respective turret about the axis of its central bearing structure  80 . 
     Latch assembly  52  includes an electric motor  90 , reduction gearing  92 , an output shaft  94 , a three pronged lever structure  96  driven by shaft  94 , turret latch assemblies  98 , and a carriage latch assembly  100 . 
     Motor  90  and reduction gearing  92  are suitably mounted on central carriage cross-members  58 . 
     Each turret latch assembly  98  includes a latch finger  102  pivotally mounted intermediate its ends on a pivot shaft  103  extending between the lugs  70   b  of a respective latch structure  70 , and a link  104  pivotally mounted at an inboard end thereof to a prong  96   a  of the lever structure  96  and pivotally mounted at its outboard end to the lower end of a respective finger  102 . 
     Carriage latch assembly  100  includes a plunger  106  and a link  108 . Plunger  106  is received in a bushing  110  in plate  66  and coacts at its lower end  106   a  with an aperture  22   a  in track structure central spine member  22 . Link  108  is pivotally connected at its lower end to the upper end of plunger  106  and pivotally connected at its upper end to prong  96   b  of the lever structure  96 . 
     Latch assembly  52  is arranged such that with the latch elements in the position seen in  FIG. 4 , and in the solid line position of  FIG. 5 , the lower end  106   a  of plunger  106  engages aperture  22   a  in spine member  22  to preclude sliding movement of the shuttle assembly on the track structure and fingers  102  are positioned between rollers  112  down standing from the rim  74   b  of each ring gear  74  to preclude rotation of the turrets relative to the carriage  46 . 
     When the latch lever  96  is rotated to the dash line position seen in  FIG. 5  by suitable energization of motor  90 , fingers  102  are rotated to a position clear of the rollers  112 , whereby to allow free rotation of the turrets on the carriage, and the lower end  106   a  of plunger  106  is withdrawn from aperture  22   a  to allow sliding movement of the shuttle assembly on the track structure. 
     In overview, energization of motor  38  operates via rollers  28  and drive elements  30  to move the shuttle assembly longitudinally along the track structure, and energization of motors  82  acts via pinions  88  and ring gears  74  to rotate the turrets with respect to the carriage with the reciprocal or rotational movement selectively precluded or allowed by selective actuation of latch assembly  52 . The reciprocal movement of the carriage along the track structure is facilitated by the rolling engagement of the side rails  54  of the carriage on the rollers  28  with lateral displacement of the carriage relative to the track structure precluded by guide rollers  113  suitably engaging the side rails of the carriage, and the rotation of the turrets on the carriage is facilitated by the bearing structures  80  and by the rolling engagement of the underface of the rim of the respective ring gear with the rollers  72 . The amount of reciprocal movement imparted to the shuttle assembly as well as the amount of rotary movement imparted to the turrets is, in each case, controlled in known manner by encoder devices associated with the respective motors. Pneumatic, hydraulic, and electric energy requirements are delivered to the shuttle assembly by flexible conduits seen schematically at  114  and it will of course be understood that a suitable control mechanism will be provided to control the movements of the various components of the body subassembly apparatus  10  including the selective control of latch assembly  52  to selectively preclude and allow linear movement of the pallet and rotational movement of the turrets. 
     The operation of the body subassembly apparatus  10  in the context of the body assembly installation seen in  FIG. 1  will now be described with attention first to the body subassembly apparatus  10  seen on the left side of  FIG. 1 . 
     The following description is on the assumption that the subassembly apparatus  10  will be utilized to perform the subassembly of a vehicle door and it will be understood that the four sides A, B, C and D of each turret have previously been outfitted with schematically illustrated tooling fixtures  116  (including clamps, risers, etc.) that are peculiar to a specific model of motor vehicle. Specifically, side A of each turret would be outfitted with fixtures  116 A specific to the assembly of a door for a Model A vehicle; side B of each turret would be equipped with fixtures  116 B specific to the assembly of a door for a Model B vehicle; side C of each turret would be equipped with fixtures  116 C specific to the assembly of a door for a Model C vehicle; and side D of each turret would be equipped with fixtures  116 D specific to the assembly of the door of a Model D vehicle. The Model A, B, C and D doors may comprise different doors for different body styles of the same basic vehicle and/or may comprise doors for totally distinct vehicles. 
     Assuming that it is desired initially to fabricate a door for a Model A vehicle, and with the shuttle assembly in the left position (as viewed in  FIG. 2 ) with the A face of the left turret facing the operator “O” and the A face of the right turret facing weld robots WR 1  and WR 2 , the operator “O” positioned at a load station LS 1  for the left hand turret would load Model A door components from bins I, II and III onto the A Model tooling fixtures  116 A positioned on the “A” face of the left turret whereafter the shuttle assembly would be moved to the right (as viewed in  FIG. 2 ) to move the right turret to the right end of the track assembly to a load station LS 2  for the right hand turret while moving the left turret to a weld/unload station WU at the center of the track assembly while simultaneously rotating the left turret through 180° so that the “A” face of the left hand turret as it arrives at the weld/unload station WU now faces weld robots WR 1  and WR 2 . Simultaneously, as the right turret moves to the right end of the track assembly the right turret is rotated through 180° to present the “A” face of the turret assembly to the operator “O” who has now moved to load station LS 2  so that, as robots WR 1  and WR 2  weld the “A” Model components positioned on the “A” face of the left hand turret, the operator “O” may load “A” Model components from bins I, II and III onto the “A” model tooling fixtures  116 A positioned on the “A” face of the right hand turret whereupon, following the simultaneous loading of the “A” face of the right hand turret and welding of the components on the “A” face of the left hand turret, the welded door may be unloaded from the “A” face of the left hand turret by a transfer robot TR 1  positioned proximate weld/unload station WU and the shuttle assembly may be moved to the left to return the left hand turret to load station LS 1  and move the right hand turret to the weld/unload station WU while simultaneously rotating each turret through 180° so that as the left turret arrives at the load station LS 1  the “A” face is again presented to the operator “O” (who has now returned to his initial position at LS 1 ) and as the right turret arrives at the weld/unload station WU the “A” face is presented to the weld robots. This simultaneous shuttling, rotating, and unloading procedure is repeated in so long as the plant manufacturing requirements are calling for the manufacture of “A” Model doors. 
     However, in a random mix assembly process in a plant capable of manufacturing several vehicle models, it is frequently necessary to effect a change-over in the subassembly procedures so as to provide door assemblies for a different model, such for example as a Model “B” vehicle. With the invention subassembly apparatus, this change-over is quickly and efficiently accomplished by simply rotating the turrets, utilizing motor assemblies  50 , through 90° whereby to present the “B” face of each turret with the  116 B tooling fixtures to the operator as the left turret is loaded at load station LS 1  and the right turret is loaded at load station LS 2 . Once the turrets have been readjusted by a simple 90° rotation to accommodate a Model “B” subassembly procedure, the previously described loading and welding procedure can be undertaken and continued so long as Model “B” door assemblies are called for. If and when Model “C” door assemblies are required, a further 90° adjusting rotation of the turret assemblies is performed and if and when Model “D” door sub-assemblies are required, a further 90° rotation of the turret assemblies is performed. If it is desired to change from an “A” Model door assembly to a “C” Model door assembly or from a “B” Model door assembly to a “D” Model door assembly this change-over is quickly and efficiently accomplished by a 180° rotation of the turrets. 
     In each case, after the robots WR 1  and WR 2  have completed their welding operation on the respective door components, the transfer robot TR 1  is utilized to unload the welded door assembly from the turret and move it to a nest N 1  where further welding on the door assembly may be provided by a weld robot WR 3  located at a respot station, whereafter a transfer robot TR 2  may be utilized to move the respotted door assembly to a further nest N 2  whereafter a further transfer robot TR 3  may be utilized to access a further door assembly part (such for example as an impact beam) from a bin IV, add it to the previously welded door assembly, and transfer the door assembly with the added impact beam to a further transfer robot TR 4  mounted on a table “T” for reciprocal movement between left and right positions (or upper and lower as viewed in  FIG. 1 ) so as to coact with a further body subassembly apparatus  10  seen on the right hand side of  FIG. 1 . In this case the transfer robot TR 4  takes the place of the manual operator “O” associated with the left hand body subassembly apparatus  10  and moves back and forth on table “T” between left and right positions to selectively load the left hand turret of the right hand apparatus  10  and the right hand turret of the right hand apparatus  10  in the manual manner previously described with respect to the left hand apparatus  10  with the shuttle assembly moving back and forth between left and right load stations as previously described with respect to the manual operator and with the turrets rotating through 180° as the turrets undergo their shuttling movement so as to present components loaded for example on an “A” face of a turret by the robot TR 4  to further weld robots WR 4  and WR 5  located at a central weld/unload station whereafter the welded door assembly may be unloaded by a transfer robot TR 5  for movement to a further respot station where further weld robots may perform further welding on the door assembly. 
     As with the left hand manual load body subassembly apparatus  10 , the turrets of the right hand robot load body subassembly apparatus  10  may be readily rotated through either 90° or 180° to quickly provide a change-over between a Model “A”, Model “B”, Model “C” or Model “D” random door requirement with the model change-over performed at the right hand robot load apparatus  10  of course corresponding in each case to the model change-over performed at the left hand manual load apparatus  10 . 
     The invention body subassembly apparatus will be seen to provide a quick and efficient means of effecting a model change-over. Specifically, model change-over is accomplished with the invention apparatus simply by rotating the turrets through the required angular amount, as compared to prior art installations where it is required for the robot to pick up the tooling at the sub-assembly location, transport the tooling to a suitable storage location, decouple all of the energy feeds for the tooling, and then, in a separate time consuming operation, pick up a new end effecter tooling corresponding to the new model requirements, couple the energy needs of the new tooling to the robot, and transport the tooling to the sub-assembly location. The total time required to simply rotate the turrets of the invention apparatus is a fraction of the time required in the prior art installation to deposit and decouple the old end effecter tooling at a suitable storage location and pick up and couple a new end effecter tooling to accomplish the proper subassembly for the new model. The overall effect is that the cost of the machinery required to provide ready and efficient subassembly of various vehicle models on a random basis is significantly reduced both in terms of the cost of the initial equipment, the maintenance required on the equipment, and the space required in the plant facility to accommodate the equipment. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention 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, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.