Abstract:
A carrier locking system for a horizontal pendulum conveyor employs a coupler at the free end of a generally L-shaped pendulum arm which interlocks with a receiver on a carrier. The coupler and receiver are normally in an unlocked position when the carrier travels along a horizontal path, and automatically interlock when the carrier travels along an inclined path. Locking the carrier to the pendulum arms prevents the carrier from becoming separated from the pendulum arms when descending into a surface treatment tank.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to improvements in overhead horizontal pendulum conveyor systems and, in particular, to a pendulum arm therefor which cooperates with a receiver on a carrier frame to lift and transport a vehicle part or other object under assembly along an inclined as well as a horizontal path, such as through surface treatment tanks, where the carrier and part may become buoyant and tend to separate from the pendulum arms. 
     In the assembly line manufacture of motor vehicles such as automobiles and trucks, it is known to provide an overhead horizontal pendulum conveyor system from which pendulum arms depend, typically in groups of four for supporting the four corners of a rectangular skid frame or carrier. These conventional pendulums hang vertically from the conveyor and have hooks on their lower ends for engaging laterally outwardly projecting arms (connecting arms) extending from the supporting frame of the skid or carrier upon which an object is transported. The connecting arms must extend beyond the maximum width of the carried object to provide clearance for the pendulums. Thus the total width of the carrier must be significantly greater than the width of the object and the supporting frame. 
     Furthermore, when the carrier and its associated object are disengaged from the pendulum conveyor and transported by other conveyor means, an excessive lateral space is consumed by the width of the carrier frame and its connecting arms, thereby increasing the area that must be clear of obstructions. Additionally, ovens for drying components, for example, must be sized to accommodate the width of the carrier, not just the object. Such carriers also require a large amount of storage space, may be difficult or cumbersome to handle, and the protruding connecting arms may be prone to damage. Once such carrier is shown in U.S. Pat. No. 4,831,962 to Gros. 
     SUMMARY OF THE INVENTION 
     It is, therefore, the primary object of the present invention to provide a pendulum conveyor in which the width of the carrier associated therewith is minimized. 
     A corollary to the foregoing object is to provide a pendulum conveyor and associated carrier which are positively interlocked during upward and downward courses. 
     Another important object of the present invention is to provide an apparatus as aforesaid which automatically locks the pendulum arms to the carrier when the carrier is not substantially horizontal. 
     Still another important object of the present invention is to provide an apparatus as aforesaid that prevents the carrier and part from becoming separated from the pendulum arms when lowered into a tank of liquid through the use of a receiver on the carrier which is positively interlocked with a mating coupler on a corresponding pendulum arm. 
     Yet another important object of the present invention is to provide an apparatus as aforesaid which has a carrier which is not prone to damage due to protruding members and minimizes maintenance. 
     A further important object of the present invention is to provide an apparatus as aforesaid which minimizes the space required for storage. 
     Another important object of the present invention is to provide an apparatus as aforesaid which accommodates smaller assembly line equipment such as ovens and processing tanks. 
     Still another important object of the present invention is to provide an apparatus as aforesaid having pendulum arms which extend generally horizontally inwardly to the associated receivers to engage and lock the carrier to the arms. 
     These and other objects of the invention are achieved by providing a generally L-shaped pendulum arm which depends from an overhead horizontal pendulum conveyor and provides a coupler at the free end of an inwardly extending, horizontal portion of the arm. The coupler is designed to engage a receiver on an associated carrier and automatically interlock when the carrier rotates and assumes an inclined orientation during a downward or upward course of the conveyor. In vehicle part process treatment applications, this eliminates the possibility of the carrier and vehicle part floating off of the pendulum arms when descending into a treatment tank. The carriers may be conveniently handled and stored during nonuse, as the receivers do not add any significant width to the carrier frames. 
     Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is plan view of a prior art carrier showing vehicle envelopes and connecting arms extending from the carrier. 
     FIG. 2 is a plan view of a carrier and receivers of the present invention. 
     FIG. 3 is a fragmentary, rear elevational view of a pendulum suspended from a conveyor and a fragmentary, rear elevational view of a carrier frame and attached receiver. 
     FIG. 4 is a fragmentary, side elevational view of a horizontal pendulum conveyor with the pendulums of the present invention partially cut away to show the coupler engaged in the receivers, and supporting a carrier and a vehicle frame illustrated in phantom lines thereon. 
     FIG. 5 is a rear elevational view of the horizontal pendulum conveyor system of the present invention showing a pair of pendulums engaged in the respective receivers attached to a carrier frame supporting a vehicle and parts illustrated in phantom lines. 
     FIG. 6 is a fragmentary, side elevational view of a portion of a horizontal pendulum conveyor showing a vehicle illustrated in phantom lines supported by a carrier frame being lifted from a conveyor by the pendulum arms. 
     FIG. 7 is a fragmentary, rear elevational view along the direction of travel of the conveyor and of the right receiver illustrated in FIG.  6 . 
     FIG. 8 is a fragmentary, rear elevational view along the direction of travel of the conveyor and of the left receiver illustrated in FIG.  6 . 
     FIG. 9 is a fragmentary, diagrammatic plan view of the horizontal pendulum conveyor system showing a carrier being lifted from a first conveyor, transferred by the pendulum arms and placed on a second conveyor. 
     FIG. 10 is a detail view showing a receiver in side elevation. 
     FIG. 11 is a right end elevational view of the receiver shown in FIG.  10 . 
     FIG. 12 is a vertical sectional view taken along line  12 — 12  of FIG. 3 showing the coupler on the same scale as FIG.  10 . 
     FIG. 13 is a fragmentary, end elevational view of the horizontal arm and coupler. 
     FIG. 14 is a perspective view of the coupler and receiver prior to engagement. 
     FIG. 15 is a vertical sectional view taken along line  15 — 15  of FIG. 8 showing the coupler engaged in the receiver, on the same scale as FIG.  10 . 
     FIG. 16 is a sectional view taken along line  16 — 16  of FIG. 15 showing the coupler engaged in the receiver. 
     FIG. 17 is a vertical sectional view similar to FIG. 15 but showing that the coupler and receiver will not separate provided the carrier is inclined at 8° or more. 
     FIG. 18 is a vertical sectional view showing the maximum rotational angle that the receiver and coupler can accommodate. 
     FIG. 19 is an illustration of a carrier and vehicle part descending into a treatment tank. 
    
    
     DETAILED DESCRIPTION 
     Referring initially to FIGS. 1 and 2, a prior art carrier or skid  500  is illustrated in FIG.  1 . Carrier  500  has connecting arms  502  extending laterally from the rectangular skid frame beyond the side projections of a large vehicle part or object illustrated by broken lines  504 , and well beyond the side projections a smaller object or vehicle part  506 . In comparison, carrier  20  of the present invention illustrated in FIG. 2 includes receivers  22  at each corner of carrier  20  and cross members  24 , none of which extend beyond the side projections of vehicle parts  504  or  506 . 
     Referring to FIGS. 3-5, an overhead horizontal pendulum conveyor system referenced generally by  26  has a pair of parallel, horizontally spaced-apart monorail I-beam tracks  28  which support and guide a number of trolleys  30 . A drive chain  32  for each track  28  interconnects trolleys  30  below the respective track. Drive chains  32  power the trolleys  30  to move conveyor  26  in the direction indicated by the arrow in FIG. 4 (from right to left). 
     Each of four generally L-shaped pendulums  34  pivotally depends from the lower portion of a corresponding C-hook  36  which is bolted to an index head  38  pivotally depending from an associated trolley  30 . Index heads  38  may pivot in line with the direction of travel of the conveyor  26 , while pendulums  34  may pivot transversely to the direction of travel of conveyor  26 . A counterweight  40  is attached to the upper end of each pendulum  34  to offset the weight of horizontal arm  42  of pendulum  34  and keep horizontal arm  42  in a generally horizontal position. The pendulums  34  are preferably constructed of steel pipe to support a heavy object or vehicle such as a sport utility vehicle. 
     Each pendulum  34  and cooperating parts are identical in construction. A coupler  44 , attached to the free end of horizontal arm  42 , is designed to engage receiver  22  attached to carrier or skid  20  to enable pendulum  34  to lift skid  20  and securely carry a vehicle  45  and parts  46 . Considering coupler  44  and receiver  22  in more detail (FIGS.  10 - 14 ), receiver  22  is generally an open rectangularly shaped box having spaced-apart generally parallel outer  48  and inner  50  walls. End walls  52  and  54  present the ends of receiver  22  and are secured to carrier  20 . A receiver  22  is preferably attached at each corner of carrier  20  (FIG. 2) to provide lifting points to evenly distribute the weight of a transported object. Outer  48  and inner  50  walls present generally arch-shaped apertures  56  and  58  respectively which are in axial alignment with receiver axis  59 . Receiver axis  59  is generally perpendicular to outer  48  and inner  50  walls of receiver  22 . Outer  48  and inner  50  walls also present aligned arcuate slots  60  and  62  which are in communication with apertures  56  and  58  respectively. Arch or saddle member  64  extends between walls  48  and  50  and is secured along the inside edges of arches  56  and  58 . The inside curvature of saddle member  64  generally conforms to the outside curvature of horizontal arm  42 . 
     Coupler  44  generally comprises of a pair of spaced-apart inverted generally triangular plates  66  and  68  each having an arcuate cut-out  70  and  72  for receiving horizontal arm  42 . Coupler  44  is welded or otherwise secured to the free end of arm  42 . Coupler plates  66  and  68  each have apertures which are in axial alignment with a locking pin axis  73  which is generally parallel to horizontal arm axis  43  and through which opposed locking pins  74  and  76  extend inwardly respectively to a channel  78  formed between plates  66  and  68 . 
     Referring to FIGS. 15 and 16, when coupler  44  is seated in receiver  22 , receiver axis  59  and horizontal arm axis  43  are in a coaxial relationship, and saddle  64  rides on the surface of horizontal arm  42  within channel  78 . The radial distance between the center line  61  of slot  60  and receiver axis  59  is approximately equal to the radial distance from horizontal arm axis  43  and locking pin axis  73 . Thus, locking pins  74  and  76  are approximately centered within arcuate slots  60  and  62 . As illustrated in FIG. 15, coupler  44  and receiver  22  are in an unlocked position. 
     Referring to FIGS. 6-8, as carrier  20  supporting vehicle part  45  travels in the direction indicated in FIG. 6 (from left to right) along inverted power and free conveyor or skid conveyor  80 , pendulum conveyor system  26  moves in synchronism so that pendulums  34  are aligned with the receivers  22 . Horizontal pendulum arms  42  on each side of skid  20  approach skid  20  approximately seven inches below the right receiver  22  in FIG.  6  and the receivers  22  shown in FIG. 7 looking in the direction of travel of conveyor  26 . Monorail  28  provides a nine inch rise thus lifting skid  20  two inches off a conveyor represented at  80  (shown in FIG. 6) and fully engaging coupler  44  and the left receiver  22  of FIG. 6 (see FIG. 8 looking in the direction of travel of conveyor  26 ). The outwardly tapered channels of arcuate slots  60  and  62  assist in guiding the coupler into the receiver as the skid  20  is lifted from conveyor  80  (see FIGS. 6,  14 ,  15  and  17 ). 
     Referring to FIGS. 6,  9  and  15 - 19 , carrier  20  transporting vehicle part  45  is lifted from conveyor  80  and carried to process dip tank  82 . Carrier  20  may pivot up to approximately 45 degrees as it descends into and ascends from tank  82 . Likewise, saddle  64  in each receiver  22  pivots on the connecting horizontal arm  42  (FIG.  18 ). As vehicle part  45  descends into tank  82 , air becomes trapped in the vehicle part  45 . Because of this trapped air, vehicle part  45  and carrier  20  may become buoyant and float in the processing liquid  84 , becoming separated from pendulums  34  and eventually sink to the bottom of processing tank  82 . Locking pins  74  and  76  interlock each receiver  22  and coupler  44  to prevent vehicle  45  and carrier  20  from separating from horizontal pendulum arm  42  of pendulum  34 . 
     After vehicle  45  is treated in processing tank  82 , carrier  20  is lowered onto inverted power and free conveyor or skid conveyor  86  and automatically released from pendulums  34 . As pendulums  34  reach the end of the overhead conveyor  26 , having released carrier  20  on conveyor  86 , the empty pendulums  34  continue around conveyor  26  as indicated by the direction arrows in FIG.  9 . Index heads  38  rotate 90 degrees so that horizontal pendulum arms  42  are parallel with the direction of travel to reduce the area required for conveyor system  26 . As the pendulums  34  reach the beginning of the conveyor system  26 , each index head  38  rotates back 90 degrees so that horizontal pendulum arm  42  is once again generally transverse to the direction of travel of carriers  20  on conveyor system  26  in order to pick-up another carrier  20 . 
     From the forgoing description it should be appreciated that the width of carrier  20  is substantially less than prior art carriers and thus inherently requires less storage space. Additionally, because the receivers  22  do not extend significantly from the sides of carrier  20 , receivers  22  are not prone to encountering normal obstructions in an assembly line environment and thereby become damaged. Horizontal arms  42  extend to engage carrier  20  only when necessary to transport carrier  20  and are otherwise parallel to the conveyor system  26  direction of travel to eliminate an unnecessary use of space around the conveyor  26  when pendulums  34  are returning to the beginning of the conveyor line. 
     It is to be understood that while a certain now preferred form of this invention has been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims and allowable equivalents thereof.