Abstract:
A plate pin assembly for use with a fixture that holds multiple plate pin assemblies for use in chassis-body marriage during the manufacturing of automobiles. The plate pin assembly has a lower end that fits into a bushing hole on the fixture to attach the plate pin assembly to the fixture, an upper end that supports or otherwise interacts with the vehicle chassis or body, and a quick-disconnect mechanism to enable fast changeover of the plate pin assemblies on the fixture when switching from one vehicle application to another.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of U.S. Provisional Application No. 60/760,706 filed Jan. 20, 2006, the complete disclosure of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to fixtures, such as those carried by Automated Guided Vehicles (AGVs) and used to install various power train, exhaust and other components to the underside of a vehicle during a final assembly process, and more particularly, to plate pin assemblies that can be interchangeably installed in a fixture in order to accommodate a number of different vehicle models. 
     BACKGROUND OF THE INVENTION 
     In the manufacturing of automotive vehicles, it is customary to preassemble components and to marry or install them to the vehicle chassis from the underside of the vehicle. Typically, the vehicle chassis is conveyed overhead on a moving conveyer, while the components to be married to the chassis are supported and transported underneath the vehicle chassis by an AGV which rides around in a track or on the floor of the assembly plant. The AGV includes a fixture for supporting the components so that when the components are lined up beneath the vehicle chassis, the fixture and components can be lifted into place and fastened to the chassis. Once the components are secured to the chassis, the empty fixture is lowered back down and the AGV resumes its position at the beginning of the loading and assembly process. 
     One challenge facing such an assembly process is the large number of vehicle model and feature combinations often produced in the same manufacturing facility. For instance, it is not uncommon for a single vehicle to offer various suspension, engine and transmission packages; each of which requires different fixture locating and nesting features in order to accommodate the different shapes and sizes of the various components. Oftentimes, a fixture will have some type of model-to-model changeover feature which allows a single AGV fixture to be used with a number of different models. One example of such a changeover feature is a flip or pivot down detail, which enables the locating and nesting features to either be manually or automatically rotated in and out of a work position. 
     Although certain types of fixtures, such as those mentioned above, have been successfully used to accommodate a wide variety of vehicle component combinations, the fixtures with all of their various locating and nesting features can become quite complex and complicated to operate. For instance, many of the locating and nesting features must be flipped in a particular sequence in order to avoid interferences with other details. This is particularly true with more congested fixtures. Furthermore, these types of fixtures are oftentimes not scaleable, in that it is economically and logistically prohibitive to retrofit the fixture to accommodate additional models and feature combinations. 
     SUMMARY 
     According to one embodiment, there is provided a work support assembly for use with a work holding fixture. In the work support assembly, a base is adapted to be mounted against the work holding fixture, and a work support member is carried by the base. A quick-disconnect mechanism is also carried by the base and is adapted to couple the work support assembly to the work holding fixture. An actuator is further carried by the base for actuating the quick-disconnect mechanism to disconnect the work support assembly from the work holding fixture. 
     According to another embodiment, a work holder assembly includes a work holding fixture including a plurality of bushing holes therein, and a plurality of work support assemblies coupled to the work holding fixture. At least two of the plurality of work support assemblies include quick-disconnect mechanisms and locating features that are spaced apart different distances for error proof assembly to the work holding fixture. 
     According to a further embodiment, an interchangeable plate pin assembly includes a base, a handle carried by the base and including a work support member and a trigger for actuation during installation or removal of the plate pin assembly, and an attachment mechanism operably coupled to the handle. Actuation of the trigger disengages the attachment mechanism so that the assembly can be inserted into or removed from a bushing hole. 
     According to other embodiments, a fixture, storage tray, and cart are provided to carry the interchangeable plate pin assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred exemplary embodiment of the invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein: 
         FIG. 1  is a perspective view of an embodiment of a tool fixture, a storage rack and a number of interchangeable plate pin assemblies; 
         FIG. 2  is a sectional view of an embodiment of an interchangeable plate pin assembly installed in a bushing hole of the storage rack of  FIG. 1 ; 
         FIGS. 3 and 4  are top perspective views of the interchangeable plate pin assembly of  FIG. 2 ; 
         FIGS. 5 and 6  are bottom perspective views of the interchangeable plate pin assembly of  FIG. 2 ; 
         FIGS. 7-9  are side elevational views of the interchangeable plate pin assembly of  FIG. 2 ; 
         FIG. 10  is a top view of the interchangeable plate pin assembly of  FIG. 2 ; and 
         FIG. 11  is a bottom view of the interchangeable plate pin assembly of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The plate pin assembly described herein is a light-weight, interchangeable device that is designed to be easily installed into and removed from a fixture, such as those found on an Automated Guided Vehicle (AGV), so that a single fixture can accommodate a large number of vehicle component combinations during the assembly process. With reference to  FIG. 1 , there is shown an example of a tool fixture  10 , a storage rack  12 , and a number of different interchangeable work support or plate pin assemblies  14 - 20 , some of which are installed in the tool or work holding fixture  10  and some of which are being stored in the storage rack. 
     Tool fixture  10  is preferably mounted atop an AGV or some other type of cart and is designed to carry one or more vehicle components, such as suspension, engine and transmission components (not shown), so that they may be installed from the underside of a vehicle chassis. In order to properly support and deliver these components to their eventual destination on the vehicle chassis, tool fixture  10  uses a different set of unique locating and/or nesting features for each vehicle model and/or component combination being installed. The locating and/or nesting features may be carried by the plate pin assemblies and can including locating pins, work abutment blocks, or the like. In any case, the fixture  10  and plate pin assemblies  14 - 20  at least partially define a work holder assembly. According to the embodiment shown here, tool fixture  10  generally includes several horizontal base plates  30 , vertical members  32 , and a number of permanently installed locations, nesting, installation and other features  34 . Because tool fixtures in general are widely known in the art, the following description will primarily focus on those features of fixture  10  that are specific to the interchangeable plate pin assemblies  14 - 20 , and will not include an in-depth recitation of known fixture components. 
     Base plate  30  is an intricately shaped, generally planar component that is designed to accommodate a wide variety of vehicle component combinations. In addition to a complex periphery  40  and one or more large interior openings  42 , base plate  30  includes a series of bushing holes  44  which are strategically located around the base plate  30  and preferably extend through the entire thickness of the plate  30 . Bushing holes  44  can be designed such that a single hole accommodates multiple plate pin assemblies, or so that each plate pin assembly has its own separate bushing hole, or other like configurations. In either case, each bushing hole  44  is designed to securely lock one or more corresponding plate pin assemblies  14 - 20  in place when they are being used, and to release them when they are to be removed and stored. 
     Storage rack  12  is a storage tray that preferably stores the plate pin assemblies  14 - 20  in an upright and organized manner when they are not being used by tool fixture  10 . According to the embodiment shown here, storage rack  12  is mounted on the same AGV or cart as tool fixture  10 , and is a horizontally aligned component that includes a number of individual slats  50 . Each slat  50  includes one or more bushing holes  52 , which are similar to those of base plate  30 , and is designed to receive and store a different set of the plate pin assemblies  14 - 20 . If additional component combinations and/or vehicle models are added, storage rack  12  can easily be retrofitted to accept additional plate pin assemblies by simply adding another slat with appropriately shaped bushing holes. Furthermore, it should be appreciated that storage rack  12  does not necessarily have to be mounted on the same AGV as tool fixture  10 . Alternatively, it is possible for storage rack  12  to be mounted on a separate stationary or movable base located in a convenient section of the assembly area, instead of on the mobile AGV, such that it stores plate pin assemblies for one or more tool fixtures, or the storage rack  12  could be mounted in an upright orientation on a wall or other vertical surface, to name but a few of the possibilities. Various types of organizational features, such as color coding the slats  50  to match corresponding colors on the plate pin assemblies, unique error-proof attachment features for each plate pin assembly, and automatic locking features (e.g. using electronic or pneumatic actuators) that only release specific plate pin assemblies in a predetermined sequence, etc. could also be utilized to improve the efficiency of the overall setup. The construction and use of such optional features will be known to those skilled in the art. 
     Turning now to  FIG. 2 , there is shown an embodiment of an interchangeable work support or plate pin assembly  14  installed in a corresponding bushing hole (not shown) of tool fixture  10 . The plate pin assembly  14  is a quick-disconnect type of device that can be joined to or separated from a tooling fixture without the use of tools or the like. Thus, “quick-disconnect” means that the mechanism used to allow the plate pin assembly to be released from the bushing hole can be actuated by simple engagement of the plate pin assembly or a part thereof. Thus, for example, the disconnect mechanism can be designed so that a human or robotic operator can simply grasp the plate pin assembly  14  to remove or install it. The plate pin assembly  14  serves as, or supports, a light-weight locator, nesting pin, or the like, for holding any type of work, such as a transmission, engine, exhaust system, or the like. The plate pin assembly  14  includes a quick-disconnect handle-grip for quick installation or removal from a bushing hole on either the tool fixture  10  or the storage rack  12 , and generally includes a handle  60 , a base  62  and an attachment mechanism  64  adapted to couple the plate pin assembly  14  to the fixture  10 , rack  12 , or the like. The base  62  carries the handle  60  and the attachment mechanism  64 . 
     Handle  60 , which is best seen in  FIGS. 2-4  and  7 - 9 , generally serves two primary purposes: first, it can support locators (not shown) or the like that contact the vehicle components being installed, and second, it provides an operator or robot with an engagement mechanism for installing or removing the plate pin assembly  14  from its bushing hole(s). According to the embodiment shown here, handle  60  generally includes a work support member such as a shaft  70 , a pedestal  72 , and an actuator such as a pivotal trigger  74 , all of which are preferably ultimately carried by the base  62 . 
     Shaft  70  is preferably a cylindrical, upright-standing member that is preferably somewhat hollow so that it can pivotally accommodate trigger  74  therein, and generally includes an upper axial end  80  where various work contactors or locators can be mounted which contact the undercarriage component being installed, a cylindrical side surface  82 , and a lower axial end  84  for mounting to pedestal  72 . Cylindrical side surface  82  includes first and second elongated slots  86 ,  88  which generally extend in an axial direction and connect with one another via a central cavity  90  located within the shaft  70 . The first elongated slot  86  is longer than the second slot  88 , as it preferably extends all the way to the lower axial end  84 , and is designed to receive trigger  74  so that the trigger  74  may be squeezed by an operator and pivoted into cavity  90 . Slot  88 , on the other hand, is shorter in axial length and provides access to the interior cavity  90 . In the event that trigger  74  becomes stuck or lodged in a compressed state, slot  88  give the operator access to the trigger  74  so that it can be dislodged. In the embodiment shown here, shaft  70  and pedestal  72  form an integral, unitary component, however, it is possible for these two components to be individual pieces. 
     Pedestal  72  is generally a horizontally aligned, flat component and includes a base  100  for securing shaft  70  in an upright position, various attachment features  102  for threadably connecting the pedestal  74  to base  62 , and a pivot block  104 . The attachment features  102  shown here are in the form of bolts that screw into threaded holes in the base, however, other types of attachment features known in the art could also be used. The pedestal  72  includes a pivot block  104 , which includes a pivot recess  106  in communication with and extending away from elongated slot  86 , such that a single L-shaped slot is formed in the handle to pivotally receive trigger  74 . As is best appreciated from  FIG. 4 , pivot block  104  also includes a transverse pivot pin  108  that extends through the block  104 , the trigger  74  and the pivot recess  106  and allows the trigger  74  to pivot into and out of shaft  70 . 
     Trigger  74  is preferably a pivotable lever designed to be grasped at an upper end  120  and to pivot about a lower end  122 . When squeezed, a contact portion  124  of the trigger  74  drives a plunger  172  of the attachment mechanism  64  down to disengage the attachment mechanism  64 . Upper end  120  of the trigger  74  preferably fans out to include a retention tongue or pivot limiting finger  125  which, as best seen in  FIG. 2 , contacts an inner surface of cavity  90  and thereby generally maintains the trigger  74  within the shaft  70 . Lower end  122  of the trigger  74  is preferably formed in the shape of a boot. This configuration contributes to the lever effect of the trigger  74  and makes for easy engagement and operation of handle  60 . Contact portion  124  is located near the ‘heel’ of the boot and includes a blunt, somewhat rounded surface for driving the plunger  172  down in response to engagement of the trigger  74 . Because contact portion  124  is somewhat rounded at a back edge, it is able to continuously roll against and smoothly make contact with the plunger  172  all throughout the pivotal travel of the trigger  74 . 
     Base  62  securely receives handle  60  and is designed to engage a corresponding surface of either tool fixture  10  or storage rack  12 , depending on whether or not the plate pin assembly  14  is being used or being stored. According to the embodiment shown here, base  62  generally includes a horizontal plate  140  and several vertical side walls  142  which together form an integral or unitary component. The upper surface of horizontal plate  140  is shaped to receive the bottom of pedestal  72 , while the bottom surface of the horizontal plate (best seen in  FIGS. 2 ,  5  and  6 ) has four feet  144  designed to rest on an upper surface of the tool fixture  10  or storage rack  12  and includes any suitable locating features such as a locator pin  146 , and several receiver bushings or pockets  148 . With specific reference to  FIG. 2 , locator pin  146  has a central axis B which is radially spaced from a central axis A of the plate pin assembly  14  by a certain distance x. The plate pin assembly  14  is designed such that when it is properly inserted into the correct, corresponding bushing hole, locator pin  146  lines up with any suitable locating feature such as a locator hole  150 . The plate pin assemblies  14 - 20  and bushing holes preferably have locator pins  146  and locator holes  150 , respectively, which are positioned at unique radial spacings x so that a plate pin assembly cannot be installed into the wrong bushing hole because the locator pin would prevent such an installation. Additional locator features, etc. could be added to the base  62 , as is appreciated by those skilled in the art. 
     Attachment mechanism  64  operably interacts with handle  60  so that plate pin assembly  14  can be installed within and removed from its corresponding fixture bushing hole, which is preferably outfitted with a bushing or sleeve  160  and retention bolt  162 .  FIGS. 3-11  show the bushing  160  of the fixture  10  carried on the attachment mechanism  64 . According to the embodiment shown in  FIG. 2 , attachment mechanism  64  is a quick-disconnect type of mechanism that generally includes a housing  170 , a plunger  172 , three ball bearings  174 , and a spring  176 . The housing  170  is preferably an elongated, cylindrical component that is open at an upper end  180 , tapered at a lower end  182 , and has an axial bore  184  that generally extends therebetween. Upper end  180  includes an exterior shoulder for attachment to base  62  and is open-ended so that plunger  172  can move in and out of the axial bore  184 . The axial bore  184  preferably includes three circular openings  186  spaced around the circumference of the bore. Each of these openings  186  is designed to receive a corresponding ball bearing  174  and provides the ball bearing  174  with enough clearance so that it can be carried by and partially protrude out of the cylindrical housing  170 , as will be subsequently explained. Plunger  172  is driven down by the heel or contact portion  124  of the trigger  74  against the force of a resilient member such as a spring  176 , and includes a head section  200 , a reduced diameter section  202 , and a blind hole  204  for receiving the spring  176 . The spring  176  biases the plunger  172  into its uppermost position as limited at least in part by engagement of the finger  125  with the inner surface of cavity  90  which limits upward travel of plunger  172  by engagement of its head  200  with heel  124 . The head section  200  provides not only a surface for the contact portion  124  to push down on, but it also includes an exterior diameter that is slightly larger than the interior diameter of the axial bore opening so that insertion of the plunger  172  is restricted. The reduced diameter section  202  preferably extends around the entire circumference of plunger  172  and is shaped and sized to receive movable elements such as ball bearings  174  when they are in a radially retracted position. Although three ball bearings are shown here, it is of course possible for the assembly to use more or less bearings than this exemplary embodiment. Spring  176  exerts an upward spring or bias force against plunger  172  and nests within blind hole  204 . 
     During installation of plate pin assembly  14  into bushing hole  44 , an operator first squeezes trigger  74  so that the trigger heel or contact portion  124  is pivoted and drives plunger  172  down against the upward force of spring  176 . This in turn causes the reduced diameter section  202  to line up with the various ball bearings  174  so that the bearings  174  may radially retract into the axial bore  184 . With the ball bearings  174  retracted, plate pin assembly  14  can be inserted into bushing hole  44  without interfering with stationary sleeve  160 . As previously mentioned, locator pin  146  has a unique position (radial spacing x) that lines up with a complimentary locator hole  150  so that base  62  can sit flushly atop an upper surface of tool fixture  10 . Following insertion of the assembly into the bushing hole, the operator can release trigger  74  which causes an upward movement of plunger  172  and a return of the ball bearings  174  to their radially outward position. This position, which is shown in  FIG. 2 , allows all three ball bearings  174  to partially protrude out of the circular openings  186  in cylindrical housing  170  so that they can interact with an interior shoulder  205  of sleeve  160  and lock the plate pin assembly  14  in place. It is possible for the plunger  172  to have one or more small indentations on its outer surface in order to facilitate proper seating of the ball bearings  174  in this locking position. In any event, the upward spring force exerted on plunger  172  causes the ball bearings  174  to create a tight, snug fit with shoulder  205  so that no play exists between the components. Once the plate pin assembly  14  is in this locked position, it may be used to install various types of vehicle components and subassemblies to the underside of a vehicle chassis. It should be recognized that a similar installation process is used to install the plate pin assembly  14  into the bushing holes  52  of storage rack  12 , and that a reverse removal process is used to remove the plate pin assembly  14 . 
     Furthermore, it should be recognized that while the previous description has been provided in the context of a manually installed and removed plate pin assembly, plate pin assembly  14  could also be installed and/or removed by a robot or some other mechanized device. It is also possible to provide an electronically connected system that coordinates the operations of the AGV, tool fixture  10  and/or storage rack  12 . When the system determined that a model changeover was needed, a computer or other electronic processing device would preferably send a signal to tool fixture  10  and storage rack  12  instructing them to release only the plate pin assemblies involved in that particular changeover. For instance, if the tool fixture  10  had six plate pin assemblies installed and a certain model changeover require four of the six assemblies to be changed, then locking mechanisms connected to the four bushing holes  44  involved in the changeover would release their respective plate pin assemblies so that only those assemblies could be removed from the tool fixture  10 . A similar process would occur with storage tray  12 , where locking mechanisms operably coupled to bushing holes  52  would allow the four old assemblies coming from the tool fixture  10  to be inserted into the storage rack  12  and stored, and would allow the four new assemblies involved in the changeover to be released for installation in the tool fixture  10 . 
     It is to be understood that the foregoing description is of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims. 
     As used in this specification and claims, the terms “for example”, “for instance” and “such as,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.