Abstract:
In a conveyor-like work-piece processing system, transport carriages move along a work path, each carriage carrying a plurality of work-piece articles. In the disclosed embodiment, the path is folded back upon itself forming two parallel paths, one above the other, with transport carriages moved vertically from the lower path to the upper path, so that the entrance to the track and the exit from the track are positioned in dose proximity to each other. Each transport carriage has a long dimension and a relatively shorter dimension, and each carriage can be reoriented selectively so that the long dimension or the short dimension can be aligned parallel to the work path. Changing the alignment of the two dimensions relative to the direction of the path permits a work piece to remain for a longer time within a given process stage or area along the work path while achieving a system flow-rate of one carriage-in-one carriage-out.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates generally to manufacturing process systems, and more specifically relates to a processing system in which work transport carriages are reoriented relative to a work path along which they are transported, enabling work-piece articles that are carried on the carriages to dwell for a longer time in one processing stage than in another while maintaining a “one-unit-in, one-unit-out balance” for the system overall. The work path along which the carriers move is folded vertically upon itself so that its beginning and its end are in the same general location. The system of this invention has wide application but has found specific use in the “wet process” operations characteristic of optical lens manufacture.  
         [0003]     2. Description of the Related Art  
         [0004]     Conveyorized continuous transport systems are known to be ubiquitous in manufacturing and processing industries. The advantage of such systems over other work transfer methods such as “Batch Processing” is that in contrast to the use of several independent and differing multi-stage processing sections, between which workloads are transported by additional robots or by hand, the continuous transport method permits “in-line” movement of workloads through many and varied multi-stage processing operations, thus eliminating the need for human or robotic intervention for moving work-pieces among and between the differing process stages or functions.  
         [0005]     However, continuous transport process systems typically require larger floor areas, e.g. more factory-floor “real estate”, than most “batch” process systems. In addition, such continuous systems can require even more floor-space when the required process times for individual processing stages within the processing system, are not uniform throughout the system.  
       SUMMARY OF THE INVENTION  
       [0006]     The work-piece transport system of the present invention preserves the advantages of continuous, balanced processing while minimizing the floor space or “real estate” required for transporting work piece articles to and through the related processing stages.  
         [0007]     In accordance with this invention, different processing time requirements at different stages of processing are accommodated by changing the orientation of the workload transport carriers, or “carriages”, according to the processing stage through which they are passing in a sequence of plural processing stages.  
         [0008]     Thus, for example, in a relatively shorter time processing stage, the articles being processed are arranged in horizontal rows substantially side-by-side along and parallel to the work or motion path, whereas in a stage requiring greater processing time, the articles are arrayed one below the other in vertical rows that are substantially perpendicular to the work or motion path. That is, in the disclosed embodiment, the transport carriages themselves are re-positioned from horizontal to vertical orientation reorienting the.  
         [0009]     At a given unit rate of feed (i.e. one unit “in” at the input end, one unit “out” at the exit end) for the transport carriage system, reorienting the articles or the transport carriages from “long” to “short” orientation relative to the work path can increase the effective dwell time (i.e. the total period of time that a work piece spends within a given process stage) by the same ratio as the ratio of the long dimension to the short dimension. The changed orientation or “stacking” of the transport carriages and the increase in dwell-time achieved thereby, further reduces the length (smaller foot-print) of the conveyor system.  
         [0010]     In accordance with the present invention, a further significant reduction in footprint is achieved by folding the conveyor vertically over itself so that the unloading (exit end) position can be located in the same general location as the loading (entrance end) position. This arrangement in effect creates two parallel, vertically spaced-apart work path portions, with the entrance end of one located conveniently near the exit end of the other. This arranged proximity of the entrance and exit ends facilitates loading and unloading of the overall system by a single robot or human operator positioned at a single physical location where both loading and unloading can be accomplished. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is an overall partial perspective representation of a work processing transport system in accordance with this invention;  
         [0012]      FIG. 2  is a detail pictorial representation of a work-piece transport carriage that is used in the transport system illustrated in  FIG. 1 ;  
         [0013]      FIG. 3  is a detail pictorial representation of part of the orientation-changing mechanism for work carriages embodied in the transport system illustrated in  FIG. 1 ; and  
         [0014]      FIG. 4  is a detail pictorial representation of a further part of an orientation-changing mechanism for work carriages embodied in the transport system illustrated in  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]     Referring now more particularly to  FIG. 1  of the drawings, the disclosed embodiment of a balanced work transport system in accordance this invention may be seen to comprise an elongate article transport guide  10  having a pair of parallel rails  12 ,  14 , with a plurality of work-piece transport carriages  50  movable along the rails from a starting or input point  20  to an ending or exit point  24 . Points  20 ,  24  for the purpose of this invention are generally arbitrary designations and no specific structural features are contemplated at this time for delivering transport carriages into the system or for facilitating their exit from the system. Any obvious and convenient arrangements may be provided, including merely accessible open ends to rails  12 ,  14 , as shown in  FIG. 1 . It should be understood readily by those having skill in this art, that portions of one or the other of rails  12 ,  14  are not shown in the drawings, for purposes of clarity of illustration.  
         [0016]     In the disclosed embodiment, the guide  10  is shown to comprise a first guide portion  16  and a second guide portion  18  which is positioned above and generally in-line with the lower portion  16 . Guide  10  may preferably have the form of a rail or track which may have a conventional rail-road track or I-beam track-like configuration, but it will be evident to those skilled in this art that other and different forms of continuous guide path structures may be used to achieve the guided movement along a specified path in accordance with the invention herein disclosed. Further, it should be understood that first and second guide portions,  16 ,  18  preferably are disposed as shown, one above the other in accordance with this invention, although in certain circumstances it may be possible to position two guide path portions at the same or substantially the same elevation.  
         [0017]     As shown most dearly in  FIG. 2  of the drawings, carriages  50  have first pairs of transport guide-engaging wheels  62  spaced apart along a relatively longer dimension X and second pairs of transport guide-engaging wheels  64  spaced apart along a second dimension Y, that is relatively shorter than dimension X. Each pair of wheels preferably includes at least one wheel common to the other, as shown, although other and different arrangements may be adopted within the spirit and scope of the disclosed invention. To achieve the benefit of the two axes X and Y in accordance with this invention, it is noted the two are positioned, or skewed, at a non-linear angle to each other. Specifically, it is anticipated that X and Y will most often be arranged at a right angle to each other, but it should be understood that other, different angles may be adopted provided only that the two dimensions are arranged in non-linear (e.g. non-parallel) relationship.  
         [0018]     In accordance with this invention, carriages  50  may be reoriented selectively relative to guide  10  so that either dimension X or dimension Y is generally parallel to the adjacent portion of the motion path defined by the guide, as shown in  FIG. 1 . In  FIG. 1 , dimension X is parallel to the adjacent portion of the guide  10  along lower guide portion  16  with wheels  62  engaged to guide  10 , while dimension Y is parallel to the adjacent portion of the guide  10  with wheels  64  engaged to guide  10  along upper guide portion  18 .  
         [0019]     It can now be seen that when carriages  50  are coupled to guide  10  via wheel pair  62  the carriages occupy a significantly greater space, i.e. length, along guide path  10  than they occupy when coupled to the guide by means of wheel pair  64 . This reorientation of the transport carriages  50  to achieve different path length occupancy is an important feature of this invention.  
         [0020]     Reorientation of work-piece transport carriages  50  is achieved by means of an orientation-changing apparatus  100 , shown most dearly in  FIG. 3  of the drawings. As shown in  FIG. 3 , orientation-changing apparatus  100  comprises a linear displacement piston and cylinder device  102  coupled to a movable section  22  of first portion  16  of transport guide  10 . In general, movable section  22  is positioned at the end  30  of first portion  16  of guide  10 , preceding the entrance  32 , to second guide portion  18 , where reorientation of work-piece transport carriages  50  from their first to their second position is desired for the purposes of the invention.  
         [0021]     As shown in  FIG. 3 , movable section  22  of guide portion  16  is pivotally mounted about an axis  26 , that allows section  22  to be displaced, by activation of cylinder  102  acting upon a lever arm  104  coupled to section  22 . One having skill in the art will recognize that one end of cylinder assembly  102  is fixed to a stationary part of the system structure while the opposite end is coupled to the movable lever that moves guide section  22 . Activation of cylinder  102  pivots guide section  22  from substantially horizontal alignment with guide portion  16  to vertical alignment substantially perpendicular to the travel path defined by guide portion  16 . Movable section  22  is dimensioned, and aligned initially, to receive the entire length of a transport carriage  50  along the dimension (dimension X) aligned with guide portion  16 , so that the length of the carriage along dimension X is reoriented, along with movable section  22 , from a substantially horizontal position to a substantially vertical position, when displacement cylinder  102  is activated.  
         [0022]     Similarly, successive carriages  50  will be displaced or “reoriented” from a first position with dimension X in parallel alignment with guide portion  16 , to a second position in which dimension Y is parallel to guide portion  18  of the guide  10 . That is, each carriage is reoriented, successively, from a first position in which the first pair of transport guide-engaging wheels  62  are disposed to travel along the guide  10  to a second position in which the second pair of transport guide-engaging wheels  64  are aligned to engage and travel along the guide  10 .  
         [0023]     In this disclosed and preferred embodiment of the invention, second work-carriage guide portion  18  is positioned above and substantially parallel to first guide portion  16 . In this configuration, first and second portions  16 ,  18  are substantially equal in length (i.e. each portion comprises substantially one-half of the total length of the work path) so that the entrance  32  to second portion  18  is directly above the reorientation end  30  of first portion  16 , and system input point  20  is in dose proximity to (i.e. substantially adjacent and below) system exit point  24 .  
         [0024]     Further, locating entrance  32  directly above end  30 , facilitates the transfer of a reoriented carriage  50  from first guide portion  16  to second guide portion  18 . That is, it can now be seen in  FIG. 4  that, after carriage  50  is reoriented from its first position (with dimension X parallel to guide  16  ) to its second position (with dimension Y parallel to guide portion  18 ) the carriage is raised vertically by a vertical transfer mechanism  150  until dimension Y is aligned parallel to the path defined by guide portion  18 . At this point, the carriage  50  is advanced linearly in the horizontal direction until the second pair of transport guide-engaging wheels  64  is fully engaged to travel along guide portion  18  and the carriage is set to continue along the processing path on that portion ( 18 ) of the transport guide, in the direction of exit point  24 .  
         [0025]     Raising carriage  50  vertically from within movable guide section  22  toward guide portion  18  is accomplished simply, as shown in  FIG. 4 , by means of vertical transport mechanism  150 . Informed by the disclosure of the invention herein set forth, the design and operation of the vertical transport mechanism  150  can be seen to comprise simply a housing  152  incorporating one or more cylinders (not seen) that receive corresponding pistons  154 . Mounted on the exterior surface of housing  152 , one or more notched racks  156  having notches  158  are located in alignment to engage one or more structural struts  52  mounted to carriage  50  as movable guide section  22  is displaced from an initial horizontal position to a second, vertical position as explained above. When struts  52  are engaged with notches  158 , carriage  50  is carried along when housing  152  is displaced in the vertical direction. Accordingly, carriage  50  is lifted vertically as pistons  154  are displaced from within the cylinders (not seen) within housing  152 , and first wheel pairs  62  travel along and out of now vertically-oriented movable section  22  of transport guide  10  until second wheel pairs  64  are aligned with the guide path defined by second guide portion  18 .  
         [0026]     To facilitate transition of wheel pairs  64  into engagement with guide portion  18 , the disclosed embodiment of the invention incorporates a pair of slidable transition track sections  26  formed at entrance end  32  of guide portion  18  (only one such section is shown in  FIG. 4  the other slidable section having been deleted from the drawing for purposes of clarity of illustration) which are coupled to a pair of linearly displaceable piston and cylinder assemblies  40  of the type that have been identified elsewhere herein. Although piston and cylinder assemblies are disclosed in several places herein as a means for achieving linear displacement of relatively movable parts, those skilled in this art will recognize that other and different forms of linear displacement mechanisms may be used for this purpose within the scope of the invention herein disclosed.  
         [0027]     With continuing reference to  FIG. 4 , it will be understood that assemblies  40  are fixed at one end to a stationary portion of the system structure, while the opposite, movable end is coupled to displace slidable track sections  26  into engagement with wheels  64  of carriages  50 , after the carriage has been vertically displaced to bring wheels  64  into alignment with the path defined by guide portion  18 . When wheels  64  are engaged on rail section  26 , the carriage may then be linearly advanced along the rail to continue its transport travel along guide portion  18 . Following each such advance, cylinder assemblies  40  are retracted to position slidable sections  26  to allow a next carriage to be advanced vertically into alignment with guide portion  18 .  
         [0028]     Throughout the description of this invention up to this point, reference has been made to advancing carriages  50  linearly in desired directions along portions of guide  10 . Although a specific means for achieving such linear advances has not been described, it will be understood by those skilled in this art, that one or more of various well known mechanisms and devices may be used for this purpose. In  FIG. 1  of the drawings, carriage-displacement piston and cylinder assemblies  42  are shown mounted to the sides of and substantially parallel to guide portions  16 ,  18  in position to engage adjacent portions of carriages  50  by means of any well-known ratchet-like mechanism. Cylinder assemblies  42  are activated to linearly advance the ratchet engaging device in the desired direction of advancement of an adjoining carriage when carriage advance is desired, and the ratchet is then withdrawn in the opposite direction allowing the ratchet to disengage from the carriage into ready position for the next carriage advance. The mechanism of achieving this form of advance of carriages  50  along guide  10  is when known and will be obvious to all those having skill in the art, and accordingly, details of placement and structure of these carriage advance assemblies  42  are not included herein. It is believed to be sufficient to point out that assemblies positioned at input end  20  of first (lower) guide  16 , and at entrance end  32  to second (upper) guide portion  18  will serve to engage and displace each newly entering carriage  50  in the desired direction and will serve to push other carriages along ahead of the one or more carriage(s) engaged by each assembly. Similarly, it will be understood that, depending upon the length of each portion of guide  10 , and the number and weight of carriages carried on each guide portion, more than one assembly  42  may be needed at intervals along each guide portion. Other and different forms of linear carriage-displacement mechanisms may be used within the scope and spirit of the disclosed invention  
         [0029]     In summary, the system of this invention operates substantially as follows: Carriages  50  bearing a plurality of work-piece articles  51  such as optical lens blanks, are delivered onto carriage guide  10  at input point  20  using either manual or mechanical (e. g. robotic) delivery means. As each new carriage is delivered into the system, it is engaged and advanced by carriage displacement assemblies  42  toward the opposite end of the corresponding guide portion (e.g. lower guide portion  16  or upper portion  18 ). Such advances are understood to be periodic depending upon the frequency of delivery and the spacing, if desired, between successive groups of carriages. During intervals between carriage advance, external apparatus independent of this invention may be advanced or otherwise applied to treat and/or manipulate work-pieces  51  carried on the carriage  50 . At the end of one portion (e.g. portion  16 ) of guide  10 , orientation-changing apparatus  100  reorients carriage  50  relative to guide  10  from say a long-dimension horizontal alignment relative to the path along guide  10 , to a shorter-dimension vertical alignment relative to the guide path. Positioning carriages  50  with a shorter dimension extending along the guide path allows a larger number of carriages to occupy any given length of the guide path and accordingly extends the time that a carriage remains on the path before it must be removed from the system in accordance with the generally desired one-carriage-in-one carriage-out operating standard. For example, if “wet treatments” take place along the relatively faster moving lower path portion of the disclosed system, longer-term drying operations may take place along the relatively slower moving upper portion of the path. Because carriages and their appended work-pieces move at different unit rates of displacement along portions of the work path that are relatively equal in length, (e.g. guide portions  16 ,  18 ), the “real estate” occupied by the disclosed system is reduced to a minimum relative to prior art systems. A still further novel feature of the disclosed system is that the disclosed reorientation and corresponding vertical “transition” from a lower path portion to an upper one achieves even greater reduction in needed “real estate” required.  
         [0030]     Although a preferred embodiment of the invention has been illustrated and described, it will be obvious to those having skill in this art that various other forms and embodiments of the invention now may be visualized, readily, by those having skill in this art, without departing substantially from the spirit and scope of the invention set forth in the accompanying claims.