Abstract:
A method of processing a work piece having an enclosure. The method comprises inserting a siphon into the enclosure, submerging the work piece in an immersion tank, removing the work piece from the tank, and draining liquid from the enclosure through the siphon. Inserting can include positioning at least a portion of a short leg of the siphon in the enclosure of the work piece. Preferably, draining includes directing liquid back into the immersion tank. After draining, the work piece can be moved to a second workstation and/or the siphon can be withdrawn from the enclosure. The method can be performed using a finishing system comprising a primary carrier, a work piece suspended from the primary carrier and defining an enclosure, and a siphon positioned in the enclosure. Preferably, the work piece is suspended above an immersion tank. The siphon can be positioned to direct fluid toward the immersion tank.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Priority is hereby claimed to U.S. provisional patent application No. 62/094,784 filed on Dec. 19, 2014, the entirely of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to finishing systems and processes for manufactured parts, and more particularly to carriers for transporting manufactured parts through a finishing process and methods relating to the same. For example, a finishing process can include a painting or an electroplating process whereby manufactured parts are immersed in a dip tank full of fluids. The shape of complex parts (e.g., containers and automotive parts) can introduce difficulty in ensuring full drainage of fluid from the parts after removal from a dip tank. 
         [0003]    To facilitate drainage of dip tank fluid from a part, parts are often provided with drain holes formed in the part. These drain holes are typically provided solely to facilitate drainage of fluids from the part, and are often otherwise undesirable. Without drain holes, complex and costly machines must be utilized to ensure good coverage of and drainage of fluid from complex parts. Without such measures, a significant amount of liquid may be lost from the dip tank during the process, which increases processing time and cost due to stoppages, re-filling, and treatment or disposal, and may also negatively affect downstream portions of the finishing process. 
       SUMMARY 
       [0004]    The present invention provides a method and apparatus of processing a work piece having an enclosure through a workstation having an immersion tank with liquid. The method comprises inserting (e.g., attaching) a siphon at least partially into the enclosure of the work piece, submerging at least a portion of the work piece (e.g., the entire work piece) in the immersion tank to thereby cause the liquid in the immersion tank to at least partially fill the siphon and the enclosure in the work piece, removing (e.g., lifting) the work piece from the immersion tank, and draining liquid from the enclosure through the siphon. In one embodiment, the siphon includes a short leg and a long leg, and inserting includes positioning at least a portion of the short leg in the enclosure of the work piece. Preferably, draining includes directing liquid from the siphon back into the immersion tank. 
         [0005]    If desired, after draining, the method can include moving the work piece to a second workstation. The second workstation can include any additional manufacturing process, such as dipping the work piece into a second immersion tank with a second liquid. After draining, the siphon can be withdrawn from the enclosure. 
         [0006]    The method can be performed using a finishing system comprising a primary carrier, a work piece suspended from the primary carrier and defining an enclosure, and a siphon having an inlet end positioned in the enclosure. When used to perform the above-referenced method, the finishing system further includes a workstation having an immersion tank, and the work piece is suspended above the immersion tank. Preferably, the siphon is positioned to direct fluid from the enclosure toward the immersion tank. An attachment means can be provided to secure the siphon to the work piece. 
         [0007]    The finishing system can also include a second workstation and a conveyor positioned to move the work piece to the second workstation. As noted above in connection with the method, the second workstation can include a second workstation having a second immersion tank. In the event that the work piece defines two enclosures, two siphons can be provided, one for each enclosure. 
         [0008]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a side view of a carrier assembly for moving a work piece between two workstations and embodying the present invention. 
           [0010]      FIG. 2  is a side view of the carrier assembly of  FIG. 1  at a single workstation. 
           [0011]      FIG. 3  is a side view of the carrier assembly of  FIG. 2  with a work piece lowered into an immersion tank. 
           [0012]      FIG. 4  is a side view of the carrier assembly of  FIG. 2  with the work piece removed from and held above the immersion tank, so that liquid flows from the work piece through a drainage siphon back into the immersion tank. 
           [0013]      FIG. 5  is a side view of a different work piece after removal from an immersion tank. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
         [0015]    A finishing system is illustrated in  FIGS. 1-4 . The finishing system includes a conveyor  22 , a carrier assembly  10 , and a plurality of workstations  18 . The carrier assembly includes a primary carrier or load bar  14  configured to be transported between the workstations  18  ( FIG. 1 ) by the conveyor  22  as part of a conveyor system. Each workstation  18  is designed to perform a different manufacturing process, such as dipping, painting, drying, drilling, or attaching another component. In the carrier assembly of  FIG. 1 , both of the workstations involve dipping. 
         [0016]    The load bar  14  can be a rigid structure that is coupled to the conveyor  22  for traveling along the conveyor  22  between work stations  18 . A work piece  26  is supported below the conveyor  22  by the load bar  14 . The work piece  26  is coupled to lower ends of one or more hangers or brackets  30 , and the load bar  14  is coupled to upper ends of the hangers  30  such that the work piece  26  is configured to hang from the load bar  14 . The hangers  30  can be pivotally coupled to the load bar  14  and the work piece  26 , and can also be rigid members, such as beams, rods, poles, shafts or bars, in some constructions. However, in other constructions, the hangers  30  can be flexible members such as chains, cables and ropes, etc. But the work piece  26  may be supported by the conveyor  22  in any manner with or without any additional structure via any convenient connection points on the load bar  14 , and the work piece  26 . In alternate constructions, additional structure, such as a skid may be coupled to the hangers  30  and connected to the load bar  14  by any connection points to carry the work piece  26 , and the work piece  26  can be directly or indirectly fastened to the skid. Regardless of whether the carrier assembly  10  includes a skid or additional structure, the work piece  26  is configured to move along with the load bar  14  via the conveyor  22 . 
         [0017]    Though the conveyor system shown in  FIG. 1-3  illustrates only a single carrier assembly  10 , the conveyor system may include any number of carrier assemblies  10 . The conveyor  22  can be part of any overhead conveyor system between the plurality of work stations  18 . Further, the conveyor system can be adapted accordingly so it moves in any suitable direction. In particular, the conveyor  22  transports the plurality of carrier assemblies  10  between the plurality of work stations  18 . The work stations  18  may include finishing stations, such as an electroplating immersion tank  32  for submerging the work piece  26  into an electro-coating liquid, as illustrated in  FIGS. 1-3 . In order to coat the work piece  26  at the finishing station, the work piece  26  is at least partially submerged in the immersion tank  32  and then removed. Depending upon the type of coating, the liquid in the tanks and the work piece  26  to be coated may be oppositely electrically charged to promote adhesion. However, the work stations  18  are not limited to such an example, and can include one or more of electro-coating, autodeposition coating, powder coating, liquid spray painting, cleaning, chemical etching, pre-treatment, and heat treating operations. Additionally, the work stations  18  can also include other types of equipment, such as an oven or drying station, a paint spray station, a cleaning station and the like. 
         [0018]    The work piece  26  is illustrated as a box or case forming an enclosure, but may be of almost any shape, and particularly a shape that forms an enclosure  34  that retains liquid when the work piece  26  is removed from the immersion tank  32 . Although some conveyor systems are equipped with complex manipulation capability, the conveyor  22  illustrated is only equipped to lower and raise the work piece  26  without tilting and rotation capability. Thus, the illustrated work piece  26  orientation required for good coverage leads to unavoidable liquid retention upon removal from the immersion tank  32 . In other constructions, the conveyor  22  and/or the carrier assembly  10  may enable tilting of the work piece  26  to enhance liquid coverage in the immersion tank  32 , but the tilting capability is often not sufficient to empty the liquid from the enclosure  34  in the work piece  26 . Thus, a drainage siphon  38  is further provided for removing the liquid that is retained by the enclosure of the work piece  26  after the work piece  26  is removed from the immersion tank  32 . 
         [0019]    The drainage siphon  38  is illustrated as a tube that includes a long leg  42  and a short leg  46  that are in fluid communication. The short leg  46  is positioned inside the enclosure  34  adjacent a bottom of the enclosure  34  and generally near a location where the liquid tends to be retained. The long leg  42  is positioned exterior to the enclosure  34  and the work piece  26 , substantially below a bottom side  50  of the work piece  26 , so that an outlet  54  defined by a distal end of the long leg  42  is lower than an inlet  58  defined by a distal end of the short leg  46 . Due to the gravitational potential energy difference between the liquid in the enclosure  34  and the outlet  54 , the liquid will be siphoned from the enclosure  34  of the work piece  26  by the inlet  58  of the drainage siphon  38 . The liquid is then discharged by the outlet  54  of the drainage siphon  38 , thereby removing most of the liquid retained by the enclosure  34  of the work piece  26 . The long leg  46  is arranged to direct the liquid through the outlet  54  of the drainage siphon  38  back into the immersion tank  32 . However, in other constructions the liquid may be discharged to another container or location. 
         [0020]    When the work piece  26  and drainage siphon  38  are initially submerged in the liquid in the immersion tank  32 , liquid enters the outlet  54  of the drainage siphon  38  and the inlet  58  of the drainage siphon  38  as liquid enters the enclosure  34 . This entry of fluid into both ends of the siphon can result in the formation of an air bubble near a pipe bend  62  between the long leg  42  and the short leg  46 . 
         [0021]    Upon lifting the work piece from the tank, the siphon will cause liquid in the work piece to flow into the inlet  58  and flow out of the outlet  54 . Specifically, the weight of the liquid in the long leg  42  is greater than the weight of the liquid in the short leg  46 , and thus liquid will flow through the long leg  42  towards the outlet  54 . The liquid from the enclosure  34  initially pulls any air bubble out through outlet  54 , after which the liquid continues to flow from the enclosure  34  to the immersion tank  32  through the drainage siphon  38 . Due to the pressure decrease from the inlet  58  to the top of the drainage siphon  38 , which is below atmospheric pressure, the liquid is lifted through the short leg  46 , from the enclosure  34  up to the pipe bend  62  where the liquid can then fall, due to gravity, through the long leg  42 , and be discharged out the outlet  54 . The liquid continues to be removed from the enclosure  34  by the drainage siphon  38  until most liquid is removed from the enclosure  34 , or the liquid level in the immersion tank  32  is at the same height as the liquid level in the enclosure  34 . 
         [0022]    The drainage siphon  38  is illustrated as a rigid tube having a rigid 180-degree pipe bend  62  fluidly connecting the short leg  46  and the long leg  42  to orient the long leg  42  downward so that the outlet  54  is below the inlet  46  of the drainage siphon  38 . In other constructions the drainage siphon  38  may be a flexible conduit configured to have the outlet  54  beneath the inlet  58 . In the illustrated construction a length L 1  of the long leg  42  is approximately twice as long as a length L 2  of the short leg  46 . In other constructions the length L 1  of the long leg  42  may instead be three times longer than the length L 2  of the short leg  46 , or any other amount longer. The length L 1  of the long leg  42  is preferably long enough that the outlet  54  is positioned below a bottom of the enclosure  34  so that all water stored in the enclosure is removed. The length L 2  of the short leg  46  is long enough that it extends to the bottom of the enclosure  34 . Alternatively, in other constructions, the long leg  42  of the drainage siphon  38  may be telescopic or collapsible so that the length L 1  of the long leg  42  can be variably increased or decreased as necessary. The short leg  46  may also be independently telescopic, or expandable and collapsible. Further, the long leg  42  and the short leg  46  may also both be independently telescopic. If the drainage siphon  38  is a flexible conduit it may also be expandable and configurable to properly direct liquid flow. 
         [0023]    In the illustrated construction, the drainage siphon  38  is coupled to an inside and/or outside surface of the work piece  26  by an attachment means in the form of a bracket  66  or fastener. Additionally, brazing, welding, permanent or removable fasteners, and the like may be used in combination with or without the bracket  66  and/or fastener to couple the drainage siphon  38  to the work piece  26 . Examples of fasteners that can be used (with or without a bracket) to attach the drainage siphon  38  to the work piece  26  include without limitation a clip, clamp, elastic element, permanent magnet, electromagnet, cable tie, clasp, hook, cord, adhesive, hook-and-loop strips or any other suitable component, or combination of components. The drainage siphon  38  can be permanently or releasably attached to the work piece  26  by a bracket  66  and/or a fastener as disclosed herein. Alternatively, the drainage siphon  38  can hang from the work piece without any additional attachment means. The drainage siphon  38  may also be frictionally fit to an integral component of the work piece  26 , or alternatively, the drainage siphon  38  may be integrally formed as part of the work piece  26 . However, in further constructions, the drainage siphon  38  may not be coupled to the work piece  26  at all, and may instead hand from the work piece or be coupled to the carrier assembly  10 , or integrated therewith, such that the drainage siphon  38  is not supported by the work piece  26 . In such constructions, the drainage siphon  38  may be maintained out of contact with the surfaces of the work piece  26 , thus preventing any interference with the surface treatment that coupling the drainage siphon  38  directly to the work piece  26  may produce during submersion in the immersion tank  32 . In some constructions where the drainage siphon  38  is coupled to the work piece  26 , the point of contact may be a preselected portion of the work piece  26  not designated or required to receive the coating or other finishing. The drainage siphon  38  may be attached to the work piece  26  or the carrier assembly  10  prior to the work piece  26  being loaded onto the conveyor system. Alternatively, the drainage siphon  38  may be attached to the work piece  26  or carrier assembly  10  at any point during the process. 
         [0024]    A process of conveying one or more work pieces  26  through a finishing process can include the following steps. First, the work piece  26  is connected to the conveyor  22  by the hangers  30 . If not pre-attached, the drainage siphon  38  is provided in communication with the enclosure  34  of the work piece  26 . The conveyor  22  is operated to transport the work piece  26  to a work station  18 . The conveyor  22  may transport the work piece  26  directly into the work station  18  along the primary direction of travel A, or may first transport the work piece  26  to a position above the work station  18  (e.g., in the case of an immersion tank holding an electrocoating liquid). A vertical drive may lower the carrier assembly  10  from the conveyor  22  so that the work piece  26  is lowered into the work station  18 . The vertical drive can include any suitable system for producing the required vertical travel (e.g., motor, or hydraulic cylinders). Alternately, the conveyor  22  may follow a path that descends to allow the work piece  26  to descend into the work station  18 . The work piece  26  can be lowered while traveling along the conveyor  22  or after stopping at a position along the conveyor  22  corresponding to the desired work station  18 . In the case where the work station  18  includes an immersion tank  32  containing an electro-coating liquid, the work piece  26  and the drainage siphon  38  are lowered into the immersion tank  32  so that at least a portion of the work piece  26  is submerged within the immersion tank  32  ( FIG. 2 ). While the work piece  26  is submerged, the liquid coats the work piece  26  and also flows into the enclosure  34  of the work piece  26 . Once the work piece  26  is coated thoroughly by the liquid, which may include one or more minor oscillations, the work piece  26  and the drainage siphon  38  are removed from the immersion tank  32  ( FIG. 3 ). The liquid then flows from the enclosure  34  of the work piece  26  back into the immersion tank  32  via the drainage siphon  38 . Once most of the liquid is removed from the enclosure  34  of the work piece  26 , the work piece  26  is transported via the conveyor  22  to another work station  18  or to an unloading area of the conveyor system. Once the work piece  26  is unloaded, the drainage siphon  38  may be removed and reused with another work piece  26  on the same or different carrier assembly  10  in the conveyor system. 
         [0025]    The system and method described herein are applicable for any number of work stations  18 . In some constructions, the carrier assembly  10  may include and support more than one work piece  26  each having a drainage siphon  38  for removing liquid from an enclosure. Additionally, referring to  FIG. 5 , more than one drainage siphon  70  may be used in conjunction with the same work piece  72  to accommodate a plurality of fluidly separate enclosures  74 , or to increase the speed at which liquid is removed from the work piece  72 .