Abstract:
A lateral transfer apparatus for an overhead conveyor comprises generally horizontally extending, side-by-side load tracks for receiving load-bearing trolleys for movement along a first track, and for movement along a second track. A transfer shuttle unit has a normal position aligned with the first track and provides a continuation thereof, and a transfer position aligned with the second track to provide a continuation of the second track. An actuator connected with the shuttle unit shifts it between the normal and transfer positions thereof at an acute angle to the tracks, thereby transferring trolleys to a position aligned with the receiving track for movement therealong.

Description:
This invention relates to overhead conveyor systems in which transfer of individual conveyors from one line to an adjacent line is accomplished by a direct line transfer. 
     BACKGROUND OF THE INVENTION 
     Overhead conveyors are utilized in various production, transportation, assembly and treatment environments to transport parts or products through various operational stages. One type of overhead conveyor employs a rotating, generally horizontal drive tube or shaft that supports trolleys from which the load is suspended. Drive wheels on the trolleys ride on the upper surface of the rotating drive tube, and each is mounted for rotation about a driven wheel axis that is non-parallel and non-perpendicular to the drive tube axis, preferably at an acute angle to the drive axis. To support the load, the trolleys are also provided with wheels that ride on rails that define the load track. In layouts where the trolleys repeatedly traverse side-by-side, supply and return sides of the conveyor (or a loop), a powered curve cannot be used unless the supply and return sides of the line are spaced apart a sufficient distance to accommodate two 90-degree turns to form a 180-degree turn at each end of the line. This typically consumes six or seven feet of floor space at each 180-degree turn, resulting in excessive dead space between the lines and restricting the design of an efficient conveyor layout. 
     SUMMARY OF THE INVENTION 
     In an embodiment of the present invention the aforementioned problem is addressed by providing a lateral transfer apparatus for the trolleys of an overhead conveyor. Closely spaced, side-by-side load tracks, which may define the supply side (infeed) and the return side (outfeed) of the conveyor, receive load-bearing trolleys for movement along a first track in one direction, and along a second, typically parallel track in the same or another direction. A transfer shuttle unit is provided which has a normal position aligned with one of the tracks and a transfer position aligned with the other track, and is actuated to shift the unit between a normal position and a transfer position at an acute angle to the supply track and the receiving track, thereby transferring trolleys on the supply track to a position aligned with the receiving track for movement along the receiving track. 
     In another aspect of the invention the shuttle unit includes a track section aligned with the supply track when the unit is in a normal position, and aligned with the receiving track when the unit is in a transfer position. A transfer zone is defined by guide structure spanning the first and second tracks and supporting the shuttle unit for movement between the normal and transfer positions. 
     In a further aspect of the present invention, each of the supply and receiving tracks has a pair of load rails presenting staggered ends at the transfer zone defining an acute angle of approximately 45 degrees with the direction of movement of the trolleys. The shuttle unit has a pair of transfer rails presenting staggered ends at the transfer zone aligned with one another at the acute angle to define a path of travel of the shuttle unit along this acute angle between normal and transfer positions. Accordingly, the track section of the shuttle unit substantially abuts the ends of the first track when the shuttle unit is in its normal position, and substantially abuts the ends of the second track when the shuttle track is in its transfer position, whereby load-bearing trolleys are transferred by the shuttle unit from a first side of a line to a second side of the line for travel in a desired direction along the second track. Thereafter, the shuttle unit returns to its normal position for the next transfer operation. 
     Other 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, embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a fragmentary, plan view of an overhead conveyor showing the supply side and the return side of the line and a lateral transfer apparatus at one end of the conveyor, a transfer shuttle unit being shown in full lines aligned with the load rails on the supply side. 
         FIG. 2  is an end elevational view of the conveyor of  FIG. 1  and additionally shows the overhead supports for the load rails. 
         FIG. 3  is a flow diagram showing the operation of a system controller. 
         FIG. 4  is a diagrammatic plan view of a particular track configuration showing the supply and return sides of a stretch of an overhead conveyor, and illustrates transfer units of the present invention at the respective ends thereof. 
         FIG. 5  is a plan view similar to  FIG. 4  showing an alternative embodiment. 
         FIG. 6  is a diagrammatic plan view illustrating a transfer with a two-way outfeed. 
         FIG. 7  is a diagrammatic plan view illustrating a two-way infeed. 
         FIGS. 8 and 9  are diagrammatic plan views illustrating an infeed and an outfeed with multiple lane selection. 
     
    
    
     DETAILED DESCRIPTION 
     Referring initially to  FIGS. 1 and 2  of the drawings, one of the terminal ends of a pair of spaced, parallel tracks  10  and  12  of an overhead conveyor is shown. It may be appreciated that the tracks  10  and  12  extend to the opposite end of the conveyor (not illustrated) and thus the tracks define an overhead conveyor line that may be employed, for example, to transport parts or products through various operational stages. The track  10  has a pair of spaced, parallel load rails  14   a  and  14   b  and the track  12  is presented by a pair of spaced, parallel load rails  16   a  and  16   b . Each pair of load rails  14   a ,  14   b  and  16   a ,  16   b  is supported in a conventional manner by a series of horizontally spaced pairs of hanger rods  18  and  20  spaced along the conveyor line (partially shown in  FIG. 2 ) and secured at their respective upper ends to overhead I-beams  22   a  and  22   b.    
     In the present invention the track  10  presents a supply track or infeed for the trolleys of the conveyor line, and the track  12  presents a return track or outfeed for the trolleys of the conveyor line. As is conventional in an overhead conveyor, a rotating drive tube  24  of the line is shown in broken lines in  FIG. 1  and terminates at the end of the track  10  at a transfer zone  26  where, as will be set forth in detail hereinbelow, trolleys are sequentially transferred to the return track  12 . Similarly, a rotating drive tube  28  for the return track  12  extends from the end of track  12  at the transfer zone  26 . 
     In  FIG. 1  it may be seen that the load rails  14   a  and  14   b  present staggered ends  30  and  32  respectively at the transfer zone  26  defining an acute angle with the direction of movement of trolleys along supply track  10 , the staggered ends  30  and  32  defining a 45 degree angle with the line of the track  10  that defines the direction of movement of the trolleys (not shown) that are advanced by the rotating drive tube  24  in the direction of the infeed indicated by the arrow  34 . Preferably, the ends  30  and  32  define a 45 degree angle (as shown in  FIG. 1 ) with the direction of movement of the trolleys. Similarly, the return track  12  terminates at the transfer zone  26  at ends  36  and  38  in linear alignment with ends  30  and  32 . The ends  36  and  38  define a 45 degree angle with respect to the return track  12  that provides the outfeed for the trolleys transferred by a shuttle  40  that, in its home position shown in full lines, receives individual trolleys delivered to the transfer zone  26  via supply track  10 , and then shifts the trolley at a 45 degree angle into alignment with the return track  12 . Arrow  42  illustrates the direction of movement of the shuttle  40  into alignment with return track  12  and return to the supply track  10 . 
     More particularly, as seen in  FIGS. 1 and 2 , the shuttle  40  comprises a pair of spaced, inverted U-shaped hanger assemblies  44  and  46  supporting a pair of laterally spaced load rail sections  48  and  50  having forward end portions  48 ′ and  50 ′ terminating at a 45 degree angle and abutting supply track ends  30  and  32  in the receiving position thereof shown in  FIG. 1 . The outer surface of a drive tube or shaft  52  is engaged by four driven wheels  54  carried by a yoke plate member  56  supported on a trolley having load wheels  57  that run on load rails  48  and  50 . As is conventional, driven wheels  54  have axes at an acute angle with respect to the axis of the drive tube  52  in order to propel a trolley thereon in an axial direction along drive tube  52  when the latter is driven by a motor  58  via a belt and pulley drive  60 . Two of the wheels  54  are seen in  FIG. 2  in engagement with drive tube  52 . This drive arrangement is employed in the present invention to convey trolleys from the supply track  10  to the shuttle  40  for transfer to the return track  12 . The 45 degree angle established by the ends  30  and  32  of the supply track  10  and the aligned ends  36  and  38  of the return track  12  provides a continuous track for the trolley load wheels as individual trolleys are delivered to the transfer zone  26  from track  10  and then shifted into alignment with return track  12  and advanced onto track  12  in the direction of arrow  90  without traversing a discontinuity in either direction when advancing over ends  30  and  32  onto rail end portions  48 ′ and  50 ′, and subsequently propelled from the shuttle  40  over ends  32  and  38  of the return track  12 . A continuous load track is thus presented in both directions of transfer to and from the shuttle  40 . Although an acute angle to each of the tracks  10  and  12  in the range of approximately 15 to 75 degrees could be employed, the 45-degree angle is preferred as laterally aligned load wheels  48  and  50  do not simultaneously roll over ends  30  and  32 , or  36  and  38 . For example, load wheel  50  clears end  32  before load wheel  48  reaches end  30 . 
     Transfer is accomplished by a linear actuator or pneumatic cylinder  62  having a drive rod  64  shown retracted in  FIG. 1 . Rod  64  is connected at its outer end to a shuttle push bar  66  shown in cross section in  FIG. 1 . A pair of spaced, parallel, horizontally extending guide rods  68  and  70  are mounted on the top of respective hanger assemblies  44  and  46  and extend across the transfer zone  26 . The guide rod  68  receives a bushing  72  slidable thereon and, similarly, the guide rod  70  receives a bushing  74  slidable thereon, both of the bushings  72  and  74  being secured to the respective ends of the push bar  66 . When cylinder  40  is actuated, its piston rod  64 , connected to push bar  66 , shifts the shuttle to the right as indicated by arrow  42  to the position thereof shown in broken lines in  FIG. 1  aligned with the return track  12 . At this time as will be discussed in more detail below, the motor  58  is energized to drive the transferred trolley on to return track  12  to the receiving drive tube  28 . After transfer, actuator  62  returns the transfer shuttle to its home position in alignment with the supply track or infeed  10 . Although not shown, it will be appreciated that a support is provided for actuator  62  to maintain it in a horizontal position at the transfer angle. 
     A programmable logic controller (PLC) may be employed as a system controller for the shuttle unit in response to sensors associated with the supply and return tracks and the rail sections of the shuttle. Referring to  FIGS. 1 and 2 , five inductive proximity sensors are shown and comprise a shuttle present sensor  80  near the termination of supply track  10 , a carrier present sensor  82  spaced above rail section  48 , a shuttle present sensor  84  below rail section  48  of the shuttle  40 , a shuttle present sensor  86  for sensing the shuttle  40  in the transferred position thereof aligned with the return track  12 , and a carrier clear sensor  88  adjacent the end of the return track  12 . 
     Referring to the flow diagram of  FIG. 3  showing the operation of the system controller, a carrier is approaching the transfer (block  90 ) and is detected by the sensor  80  ( FIG. 1 ). If sensor  82  indicates that the shuttle  40  is present at the home position, it produces a “Shuttle Home” output at  92  (YES) to initiate shuttle motor  58  to drive shaft  52  and propel trolleys on to load rail sections  48  and  50  of transfer zone  26 . Shuttle present sensor  84  stops motor  58  when the shuttle is in its unload position, and initiates actuator  62  to transfer load rail sections  48  and  50  to an unload position in alignment with load rails  16   a  and  16   b  of the return track  12 . Sensor  86  detects the shuttle in its unload position. If the return track  12  is clear (sensor  88 ) and the drive motor (not shown) for track  12  is in operation, motor  58  starts and drives shaft  52  to propel the trolleys onto return track  12  in the direction of arrow  90 . Motor  58  is de-energized when the carrier clears sensor  88 . Actuator  62  then returns the shuttle to its home position shown in full lines in  FIGS. 1 and 2  where load rail sections  48  and  50  are in alignment with parallel rails  14   a  and  14   b  of the supply track  10 . The shuttle  40  is thus returned to its home position for sequentially receiving additional trolleys from the supply or infeed track  10  and sequentially transferring them to the return or outfeed track  12 . 
     Referring to  FIGS. 4-9 , six track configurations are shown diagrammatically and comprise examples of conveyor configurations that may be employed with the angular lateral transfer apparatus of the present invention.  FIG. 4  illustrates a supply track  100  having a drive tube  102  partially shown) driven by a motor  104  for advancement of trollies in the direction of arrow  106 . A transfer zone  108  at one end is provided with the shuttle  40   a  of the present invention for transfer of trolleys at a 45 degree angle to a return track  112  for movement in the opposite direction as shown by arrow  114 . A drive tube  118  associated with return track  112  is diagrammatically illustrated and powered by a motor  116 . The opposite end of the conveyor configuration has a transfer zone  110  where a shuttle  40   b  shifts the trolleys at a 45-degree angle in the direction of arrow  120  into alignment with supply track  100  for movement in the direction indicated by arrow  106 . Accordingly, utilizing the 45-degree shuttles  40   a  and  40   b , a continuous loop is provided utilizing parallel, closely spaced tracks  100  and  112 . 
       FIG. 5  is an illustration similar to  FIG. 4  except that a shuttle  40   c  at the end of the supply track shifts the trolleys at a 45-degree angle in the direction of arrow  122  at a 90-degree angle with respect to the directional arrow  109  in  FIG. 4 . Operation is otherwise the same as  FIG. 4  with the return to the supply track being executed by shuttle  40   d.    
     Referring to  FIG. 6 , in this illustration the transfer is effected at a mid-point in parallel tracks or at another location spaced from the ends thereof. Aligned tracks  122  and  122   a  terminate at  126  at a 45-degree angle and define a transfer zone where a shuttle  40   e  may deliver trolleys to either of the aligned tracks  128  and  130  for movement along outfeed track  128  in the direction illustrated by arrow  132 , or movement along outfeed track  130  in the direction indicated by arrow  134 . The direction of delivery is controlled by the shuttle drive motor  136 . 
     The track configuration shown in  FIG. 7  is similar to  FIG. 6 , but with track  130  omitted.  FIG. 7  illustrates trolleys advancing along the supply track either from direction  136  or the opposite direction  138 , and then transferring via shuttle  40   f  to an outfeed track  139 . 
       FIG. 8  illustrates a multiple track outfeed. Trolleys advance along the infeed track  140  in either of two opposing directions  146  and  148  to a shuttle  40   g  for transfer to either outfeed track  142  or  144 . In  FIG. 9 , an arrangement similar to  FIG. 8  but reversed in flow is shown wherein infeed tracks  150  or  152  deliver trolleys to shuttle  40   h  for transfer as indicated by arrow  154  to either of the outfeed tracks  156  or  158  for movement in either direction  160  or in the opposite direction  162 . From the foregoing it may be appreciated that various supply and return combinations can be employed with the lateral transfer apparatus of the present invention as dictated by the design of a conveyor layout. 
     It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims.