Abstract:
A vehicle assembly system automatically decks and automatically fastens body components to chassis components. The system uses an automatic decking and fastening unit that includes a base with an elevatable platform repositionable relative to the base by at least one actuator. A slidable unit carries a fastener driver, is supported on the elevatable platform, and is repositionable relative to the elevatable platform by at least one other actuator. The slidable unit also carries an arm that is repositionable relative to the slidable unit by yet another actuator. A pair of conveyors are positioned away from the base, are movable relative to the base and carry a pair of vehicle components. The conveyors are cycled so that the vehicle components are positioned relative to one another in a predetermined position, and the actuators are operated to reposition the fastener driver to a position determined by engagement of the slidable unit with one of the vehicle components.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates to an automatic vehicle component assembly system, and more particularly, to an automatic decking and automatic fastening (ADAF), apparatus and method that effects automatic decking and automatic fastening of vehicle body components to vehicle chassis components.  
         BACKGROUND OF THE INVENTION  
         [0002]    One of the most impressive operations in a vehicle assembly plant involves the marriage of a vehicle body structure to its chassis. For a pick-up truck, this process is generally subdivided into assembly of the passenger cab to the frame and assembly of the utility box to the frame. Commonly used methodology involves a substantial reliance upon manual intervention to accomplish this complex task. In the case of a pick-up cab, a subassembly that can weigh in the neighborhood of 1200 pounds (545 kilograms), is supported by equipment and manually guided into position to align or “justify” the cab relative to the frame, before lowering it onto the frame to effect decking. In addition, manpower is used to guide the machinery that individually applies the fasteners for securing the components together. Automating this type of vehicle assembly process is highly desirable due to the labor intensive and physically demanding operations involved.  
         SUMMARY OF THE INVENTION  
         [0003]    Aspects of the present invention involve automation of the process that decks and secures a vehicle body component to its chassis. In accordance with these aspects, an automatic decking and automatic fastening system includes a base with an elevatable unit repositionable relative to the base by at least one actuator. Preferably, the elevatable unit is compliant in the fore-aft direction. This preferred fore-aft compliance is useful in accommodating any experienced chassis carrier stopping error. A cross-car slidable unit is supported on the elevatable unit and is repositionable relative to the elevatable unit by at least one other actuator. Preferably, this other actuator can stop and hold position when an element of the chassis such as a frame bracket has been located. Tooling (referred to in the following detailed description of the preferred embodiment as an ADAF plate), is carried on the slidable unit and is repositionable vertically relative to the slidable unit by yet another actuator. The tooling locates off the chassis element and serves to carry and to justify the body component to the chassis. A fastener driver is preferably carried by a compliant assembly on the slidable unit. This assembly allows the fastener driver to have a preferred compliance in the cross-car and fore-aft directions relative to the slidable unit, and allows the fastener driver, with its own lead in tooling, to locate a mounting fastener.  
           [0004]    According to preferred aspects of the present invention, the body element is positioned in space at a predetermined location. The actuators are operated to reposition the tooling to accept and justify the body element to a position determined by engagement of the tooling with the chassis. The justified body element is lowered to the chassis, the tooling is retracted, and the fastener driver advances fastening the body element to the chassis. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    The present invention will now be described, by way of example, with reference to the accompanying drawings in which:  
         [0006]    [0006]FIG. 1 is an illustration of one side of the cab to frame marriage station of an ADAF apparatus showing one ADAF unit.  
         [0007]    [0007]FIG. 2 is an illustration of the cab to frame marriage station of an ADAF apparatus with both ADAF units shown in an initial stage of the marriage sequence.  
         [0008]    [0008]FIG. 3 is an illustration of the cab to frame marriage station of an ADAF apparatus shown in an operative stage of the marriage sequence with the ADAF units ready to locate off the chassis frame.  
         [0009]    [0009]FIG. 4 is an illustration of the cab to frame marriage station of an ADAF apparatus shown in an operative stage of the marriage sequence with the ADAF units located off the chassis frame and the cab in a pre-deck position.  
         [0010]    [0010]FIG. 5 is an illustration of the cab to frame marriage station of an ADAF apparatus shown in an operative stage of the marriage sequence wherein the cab transfer has landed the cab onto the ADAF plates, and the cab is now justified to the chassis frame via the ADAF plates.  
         [0011]    [0011]FIG. 6 is an illustration of the cab to frame marriage station of an ADAF apparatus shown in an operative stage of the marriage sequence wherein the cab has been lowered onto the chassis frame and the ADAF plates are being retracted.  
         [0012]    [0012]FIG. 7 is an illustration of the cab to frame marriage station of an ADAF apparatus shown in an operative stage of the marriage sequence wherein the fastener drivers advance to fasten the cab screw.  
         [0013]    [0013]FIG. 8 is an illustration of the cab to frame marriage station of an ADAF apparatus shown in an operative stage of the marriage sequence with the fastener drivers retracted to the same position as shown in FIG. 6.  
         [0014]    [0014]FIG. 9 is an illustration of the cab to frame marriage station of an ADAF apparatus shown in an operative stage of the marriage sequence with the elevatable units lowered to enable ADAF unit retraction while clearing the vehicle&#39;s rocker panel.  
         [0015]    [0015]FIG. 10 is an illustration of the cab to frame marriage station of an ADAF apparatus shown in an operative stage of the marriage sequence wherein the slidable unit retracts to home position to allow the conveyor system to index the married cab and chassis out of station.  
         [0016]    [0016]FIG. 11 is a fragmentary schematic illustration of the end effector tooling usable with the cab to frame marriage station of the ADAF apparatus shown in FIGS.  1 - 10 , illustrated in a disengaged position.  
         [0017]    [0017]FIG. 12 is a fragmentary schematic illustration of the end effector tooling of FIG. 11 shown in an engaged position. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    Referring to the drawings, illustrated in FIG. 1 is one fixture, referred to as ADAF unit  12 , of an automatic decking and automatic fastening system  10 . Generally, the ADAF unit  12  is operable to position fastener driver  18  relative to a first vehicle component (not shown in FIG. 1), and to position a second vehicle component relative to the first vehicle component. This is accomplished by operation of a plurality of actuators designated as cylinders  14 - 17 , which are pneumatic in the present embodiment. The ADAF unit  12  is described within the application of assembling a pick-up cab to its frame, but is useful in the assembly of many types of vehicle body components to their associated vehicle chassis components.  
         [0019]    More specifically, ADAF unit  12  includes a base assembly  20  that is anchored to foundation  19  in a conventional manner. The base assembly  20  includes a horizontal structure  21  that supports vertical riser  22 , with a gusset fixed between the two for added rigidity. An elevatable unit  24  is carried by the base assembly  12  and includes a platform  25  and a vertical leg  26  each fixed to another gusset. A pair of bearings  27  and  28  are positioned between the vertical riser  22  and the vertical leg  26  permitting relative vertical movement there-between. The elevatable unit  24  is positioned vertically relative to the base assembly  20  by a joined pair of actuators designated as cylinder  14  and cylinder  15 . Cylinder  14  includes an extensible rod that is connected to base assembly  20  and cylinder  15  includes an extensible rod that is connected to elevatable unit  24 . By selectively varying the power fluid pressure in cylinders  14  and  15 , the vertical position of the elevatable unit  24  relative to the base assembly  20  is automatically varied to carry out the operations of the ADAF system  10 .  
         [0020]    A slidable unit  30  is carried by the platform  25  and includes a base plate  31  and an upwardly extending vertical arm  32  with a gusset fixed there-between. A slide assembly  34  is positioned between the base plate  31  and the elevatable unit&#39;s platform  25 . To position the slidable unit  30  in the cross-car direction relative to the vehicle being assembled, the slide assembly  34  includes a pair of bearings  35  and  36  along with an actuator in the form of cross-car cylinder  17  that has an extensible rod connected to the slidable unit  30 . To allow positionability of the slidable unit  30  in the fore-aft direction relative to the vehicle being assembled, the slide assembly  34  includes a pair of bearings  38  and  39  along with a well known type of spring centering mechanism  40  that extends between the slide assembly  34  and the elevatable platform  25 . Bearings  35 ,  36 ,  38  and  39  in combination with cylinders  14 ,  15  and  17 , and centering mechanism  40  enable omnidirectional positionability of the slidable unit  30  including base plate  31 , relative to the base assembly  20 .  
         [0021]    The end effector assembly  65  of the ADAF system  10  includes a power operated fastener driver  18  of a type well known in the art that is carried by a compliant assembly  41  on the slidable unit  30 , and exhibits an upwardly facing rotating tool  42  that is disposed within a spring loaded guide  44 . The compliant assembly  41  is of a well known type and allows the fastener driver to be compliant in the cross-car and fore-aft directions relative to the slidable unit through the use of elements that are displaceable under force, such as springs. This compliance allows the fastener driver, with its own lead in tooling, to move into alignment while locating the cab mount screw. The rotating tool  42  is selectively positioned along with the slidable unit  30  in an automatic manner. In addition, the fastener driver  18  is operated automatically during procedures of the ADAF system  10 . This automatic fastening system for the fastener driver records the product sequence number and all cab mount torques for quality assurance and flags any non conformities for correction to specification.  
         [0022]    A decking arm  45  is also carried on the slidable unit  30  and includes tooling, referred to as ADAF plate  46 , that is vertically movable relative to the rotating tool  42 . Bearings  47  and  48  are positioned between the decking arm  45  and the vertical arm  32  of slidable unit  30 . A cylinder  16  extends between slidable unit  30  and decking arm  45  providing the motive force for vertically positioning the decking arm  45  and the ADAF plate  46  relative to platform  25 . The ADAF plate  46  justifies the cab to the chassis frame and includes an angled top surface to facilitate locating on the cab  51 . When cylinder  16  is retracted, the ADAF plate  46  is positioned relatively close to the rotating tool  42 . This allows the cab to be decked to the chassis frame and the fastener driver to re-engage the chassis frame to fasten the cab screws.  
         [0023]    Referring to FIG. 2, it can be seen that the ADAF unit  12  is one of two substantially identical mirror-image ADAF units  11 ,  12  included in the cab to frame marriage station of ADAF system  10 . In FIGS.  2 - 10  the gusset plates of ADAF units  11  and  12  are removed for improved clarity. Additionally, components of ADAF unit  11  that are like those of ADAF unit  12 , carry the same numerical designation with the addition of a prime symbol. Above the ADAF units  11  and  12 , a marriage transfer  50  supports cab  51 , and operates to lower the cab  51  onto the ADAF units  11  and  12 . Preferably, a trim conveyor (not illustrated), initially carries the body components and a chassis conveyor  52  carries the chassis component. The trim and chassis conveyors are alternatively shuttled along the same path. The cab and the utility box (not illustrated), are lifted from the trim conveyor and repositioned above the ADAF units  11  and  12  relative to one another in a predetermined position by the marriage transfer  50 . Between the ADAF units  11  and  12 , chassis conveyor  52 , which is of a conventional type such as an automatically guided vehicle, supports a frame  53 , and operates to bring the frame  53  into position relative to the ADAF units  11  and  12 . In the present process sequence stage, the cab  51  is positioned prior to being lowered, and the frame  53  is positioned between the ADAF units  11  and  12 . To initiate an automatic decking and fastening system cycle, a signal to begin prompts operation of the cylinders  15  and  15 ′, which extend to full stroke as shown, raising the elevatable units  24  and  24 ′. At this stage cylinders  14 ,  14 ′,  16 ,  16 ′,  17  and  17 ′ are fully retracted. In this position the Marriage station is ready to place the cab  51  onto the ADAF units  11  and  12 .  
         [0024]    Referring to FIG. 3, when the cylinders  15 ,  15 ′ are fully extended a signal is sent to prompt cylinders  16 ,  16 ′ to extend to full stroke, at which point the ADAF units  11  and  12  are ready to locate the chassis frame. As shown in FIG. 4, when the cylinders  16 ,  16 ′ are fully extended and the chassis conveyor is in position, a signal is sent to prompt cross-car cylinders  17 ,  17 ′ to extend to a stall condition occurring when ADAF plates  46 ,  46 ′ are positioned against chassis frame brackets  55 ,  56 . At the stall position, cylinders  17 ,  17 ′ are locked in place. Optionally, movement of the cylinders  15 ,  15 ′,  16 ,  16 ′,  17  and  17 ′ may occur simultaneously or in any sequence to effect location of the ADAF units  11  and  12  to the desired position, with the ADAF plates  46 ,  46 ′ engaging brackets  55 ,  56 . The sequence depends on the line of attack that is open, which is dictated by the specific shape of the product being married together. The ADAF plates  46 ,  46 ′ are prepared to accept the cab  51  from the marriage transfer  50  and justify it to a position determined by engagement of the ADAF plates with the cab and with the brackets  55 ,  56 .  
         [0025]    Referring to FIG. 5, the next stage involves marriage transfer  50  lowering cab  51  onto ADAF plates  46 ,  46 ′ of the decking arms  45 ,  45 ′, which receive and carry the cab  51 . In this position, the cab&#39;s bearing plates  57 ,  58  are aligned with the mounts  60 ,  61  of the frame  53 , with the end effectors of the ADAF units  11  and  12  positioned below the mounts  60 ,  61 . Referring to FIG. 6, cylinders  16 ,  16 ′ are fully retracted so that the decking arms  45 ,  45 ′ lower the cab  51 . The bearing plates  57 ,  58  rest on the mounts  60 ,  61  respectively, decking the cab  51  to the frame  53 . At this point a signal is sent to initiate operation of the fastener drivers  18 ,  18 ′ at a slow speed. Referring to FIG. 7, the cylinders  14 ,  14 ′ are extended so that the rotating tools  42 ,  42 ′ engage the fasteners. As the fastener drivers start to drive the cab screws, the fastener drive torque increases to a level which causes the fastener controlling system to trip to high speed, rapidly driving the fasteners. When a preset torque is reached, the fastener drivers stop rotating and a signal is sent to retract cylinders  14 ,  14 ′.  
         [0026]    Reference is directed to FIGS. 11 and 12 to clarify operation of the end effector tooling. A preferred mechanism for locating the fastener drivers relative to the fasteners is shown in a simplified schematic manner. Bracket  55  is rigidly connected to frame  53  and is preassembled with a fastener  64 . The end effector assembly  65  includes fastener driver  18 , spring loaded guide  44 , and locator  67 . In its initial position, the axis  68  of rotating tool  42  is not aligned with the fastener  64 , but is positioned slightly inboard therefrom. As cylinder  14  is extended, the locator  67  engages the side rail of frame  53 . Locator  67  includes an angled wall  69  that effects alignment of the rotating tool  42  with the fastener  64  when the terminal end  70  of the locator engages frame  53 . The guide  44  includes a flared circular opening  71  to assist in capturing the head of fastener  64  and directing it to rotating tool  42 . Initial slow speed rotation of the tool  42  also facilitates capture. During this process, in effect, the tooling is permitted to float by the centering mechanism  41 . As the rotating tool  42  drives the fastener  64  home, the guide retracts, compressing a spring that biases the guide outwardly along the rotating tool  42 .  
         [0027]    Continuing with reference to FIG. 8, cylinders  14 ,  14 ′ retract, withdrawing the end effectors  65 ,  65 ′. Next, as shown in FIG. 9, cylinders  15 ,  15 ′ retract, clearing the decking arms  45 ,  45 ′ from the cab  51  and frame  53 . Finally, the cross-car cylinders are unlocked and retracted as shown in FIG. 10, so that the ADAF units  11  and  12  are returned to their home positions and readied for another cycle of the ADAF system  10 . The conveyor  52  moves the assembled cab  51  and frame  53  out from the automatic decking and fastening system marriage station.  
         [0028]    Accordingly, automation of the process that decks and secures a vehicle body component to its chassis is provided that eliminates labor intensive operations previously associated with the marriage process.