Abstract:
A circuit-like system which includes a lower conveyor line, an upper conveyor line and a pair of lift or transfer mechanisms at the end of each line constructed for moving a work piece. A travel and hoist mechanism and a beam assembly are provided for discontinuously moving work pieces along the lower line and raising and lowering them for treatment. A hook assembly is provided for restraining the downward movement of a work piece at a selected location when the hook assembly is in an operative position.  
     The lift or transfer mechanism is provided which includes telescoping arms for grasping a work piece, which arms are carried by a vertically moveable carrier that is mounted in a stationary frame.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a circuit-like conveying system whereby work pieces are moved to various treatment stations and more particularly to a system for moving the work pieces along a generally horizontal path in a discontinuous manner and vertically as required and to a related transfer or lift mechanism.  
           [0002]    Conveyors for moving work pieces from place to place or to treatment stations are well known, One conveyor type moves work pieces from place to place in a continuous manner. Another type of conveyor moves the work pieces in a start/stop or discontinuous manner so that the work pieces can be treated (usually dipped) at various stations. Such treatment may include painting, plating, cleansing and the like. Conveyors of this type move the work piece along a horizontal path, then the work piece may be stopped, moved vertically downwardly at a given station so as to dip the work piece in a treatment tank, upwardly out of the tank and then back along the horizontal path. A transfer or lift mechanism, positioned at the end of the conveyor, is provided for moving the work piece from one path or conveyor line to another. Conveyors of this type may receive untreated pieces from a remote conveyor and deliver treated pieces to the remote conveyor.  
           [0003]    In a circuit-like conveying system there is provided a first or lower horizontal conveyor line or path along which the pieces are moved, stopped, lowered, treated, raised and moved to the end of the line. At the end of the line the pieces exit the first horizontal conveyor, are retrieved and moved vertically upwardly or delivered to the entrance to a second or upper horizontal line which may be a drying oven or drying station. The pieces are moved horizontally along a second or drying line (usually in an opposite direction to the first conveyor) to the exit of the second line and may be returned to the remote conveyor and an untreated piece can be retrieved and delivered to the entrance for the first conveyor. This type of movement is seen in connection with plating machines and the like and generally defines a circuit. Machines of this type are known in the prior art but are believed to be complex and unreliable.  
           [0004]    It is an object of this invention to provide an improved circuit-like conveying system of the type described above which is less complex and more reliable than machines of the prior art.  
           [0005]    Systems of the type described herein include a transfer or lift station at the exit end of the first line for retrieving treated pieces and moving the pieces upwardly for delivery to the entrance to a second conveyor line for drying or the like. A transfer station at the exit end of the second line is provided for removing dried pieces and delivering them to a remote conveyor. The transfer station or lift can also retrieve untreated pieces from the remote conveyor and move or deliver them into the entrance end of the first treatment line. Transfer or lift mechanisms in the prior art tend to be complex, unreliable and not identical at the respective ends of the lines.  
           [0006]    It is an object of this invention to provide improved transfer stations or lift mechanisms which are less complex, reliable and substantially identical so that one can be placed at the end of the treatment line or the drying line for the movement of work pieces.  
           [0007]    With respect to the first conveyor, the work pieces are substantially equally spaced from one another and are moved downwardly as a group into treatment tanks, treated, moved upwardly as a group and then moved on to the next station for additional treatment.  
           [0008]    It is an object of this invention to provide an improved system for moving the work pieces as a group a fixed distance, dipping them into a plurality of tanks for treatment, raising them and moving them on to the next station.  
           [0009]    These and other objects of this invention will become apparent from the following description and appended claims.  
         SUMMARY OF THE INVENTION  
         [0010]    There is provided by this invention an improved circuit-like conveying apparatus for the movement of work pieces between various treatment stations and a transfer station or a lift mechanism for retrieving work pieces from one conveyor and delivery to a second conveyor. The apparatus includes a frame and a plurality of treatment stations positioned relative to the frame. A travel mechanism carried on the frame is moveable relative to the frame between adjacent treatment stations. A hoist mechanism, which is carried on the travel mechanism, cooperates in moving the work pieces between lower treatment and upper movement positions. A beam, which cooperates with the hoist mechanism, extends along the frame and is connected to the hoist mechanism, preferably by an electrically driven retractable and extendable mechanism, carries or supports the work pieces and is constructed to release work pieces when they are in treatment tanks. By this construction a work piece can be releasably secured to the beam, lowered for treatment, raised and moved horizontally from the entrance to the exit of the lower or treatment line. The work pieces are releasably secured to the beam and are constructed to be released when positioned in a treatment station tank so that the beam can be moved rearwardly one station and then raised so as to grasp a subsequent or trailing work piece and move it forwardly to the next station. In this way the work pieces are moved from tank to tank.  
           [0011]    A transfer station or lift apparatus for retrieving a work piece is provided at the exit end of the conveyor or treatment line and is arranged to retrieve a work piece at the exit end and transport the work piece to the entrance end of another conveyor which is horizontally disposed above the first conveyor. The similar transfer apparatus or lift station is provided at the exit end of the upper conveyor for movement of a treated piece to a remote conveyor. The lift apparatus may also retrieve an untreated work piece from the remote conveyor and transport it to the entrance end of the lower treatment conveyor.  
           [0012]    In this way an untreated piece can be removed from the remote conveyor, moved to the first or treatment conveyor, then moved to the second or drying conveyor and then retrieved from the drying conveyor and moved to the remote conveyor. As is seen the apparatus provides a circuit-like system for movement of the work pieces as well as subassemblies such as the travel mechanism, hoist mechanism and lift apparatus  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a side elevational view showing a circuit-like conveying apparatus which includes a first or lower treatment line, a second or upper drying line, lift mechanisms at the end of the lines and mechanisms for raising, lowering and moving work pieces in the lower treatment line.  
         [0014]    [0014]FIG. 2 is an end elevational view taken along line  2 - 2  of FIG. 1 showing the conveying apparatus frame, the upper and lower lines and a treatment tank positioned below the lower line.  
         [0015]    [0015]FIG. 3 is a diagrammatic and perspective view showing work pieces associated with a beam mechanism and positioned for lowering into a plurality of treatment tanks.  
         [0016]    [0016]FIG. 4 is an end elevational view of a portion of the apparatus as seen in FIG. 2 showing a work piece positioned for lowering into a treatment tank.  
         [0017]    [0017]FIG. 5 is a view similar to FIG. 3 showing the support beam lowered and work pieces lowered into a plurality of treatment tanks.  
         [0018]    [0018]FIG. 6 is a view similar to FIG. 4 showing a work piece lowered into a treatment tank.  
         [0019]    [0019]FIG. 7 is a view similar to FIG. 5 showing the work pieces in the tanks and the rearward movement of the support beam.  
         [0020]    [0020]FIG. 8 is a view similar to FIG. 6 showing a work piece supported at the top of the tank and the support beam free to move rearwardly.  
         [0021]    [0021]FIG. 9 is a perspective view of a fragment of the beam, hanger and tank showing the support beam moved downwardly and out of engagement with the hanger mechanism.  
         [0022]    [0022]FIG. 10 is a perspective similar to FIG. 7 showing the support beam raised and the work pieces raised from the tank and the beam positioned to receive a new work piece.  
         [0023]    [0023]FIG. 11 is a perspective view similar to FIG. 10 showing the support beam and work piece being moved forwardly so as to index the system forwardly one unit.  
         [0024]    [0024]FIG. 12 is a perspective and diagrammatic view of a circuit-like conveying apparatus as in FIG. 1 and showing the travel and hoist mechanism for moving the support beam and lift mechanisms at the end of the conveyor lines.  
         [0025]    [0025]FIG. 13 is a side elevational view of a portion of the lower conveyor showing a hook mechanism for preventing the lowering of a work piece.  
         [0026]    [0026]FIG. 14 is a side elevational view showing a piston-and-cylinder apparatus for operating the hook mechanism.  
         [0027]    [0027]FIG. 15 is a perspective view showing the hook mechanism.  
         [0028]    [0028]FIG. 16 is side elevational view showing the hook mechanism grasping a work piece.  
         [0029]    [0029]FIG. 17 is a side elevational view showing the hook mechanism in an operative position to restrain a first work piece and a second work piece in a lowered position.  
         [0030]    [0030]FIG. 18 is an exploded perspective view showing the support beam and the travel and hoist mechanisms for causing the beam to index one station and for raising and lowering the beam relative to the frame.  
         [0031]    [0031]FIG. 19 is a diagrammatic and perspective view showing a pulley and cable system for operating the hoist mechanism and a chain system for raising and lowering the beam.  
         [0032]    [0032]FIG. 20 is similar to FIG. 19 but with the hoist mechanism and beam in an extended position.  
         [0033]    [0033]FIG. 21 is a plan view showing the travel and hoist mechanisms.  
         [0034]    [0034]FIG. 22 is an elevational view showing the travel and hoist mechanisms connected to the beam and taken along line  22 - 22  of FIG. 21.  
         [0035]    [0035]FIG. 23 is a side elevational view of a traveler mechanism and taken generally along lines  23 - 23  of FIG. 21.  
         [0036]    [0036]FIG. 24 is a perspective view of a lift mechanism whereby work pieces can be retrieved from one conveyor and moved to a second conveyor.  
         [0037]    [0037]FIG. 25 shows an arm and a saddle mechanism carried by the lift mechanism for engaging, supporting and moving a work piece and is taken along line  25 - 25  of FIG. 24.  
         [0038]    [0038]FIG. 26 is an end elevational view taken along line  26 - 26  of FIG. 24 showing an arm or rail associated with the lift mechanism.  
         [0039]    [0039]FIG. 27 is a side elevational view of the lift mechanism showing an arm with a work piece in various positions.  
         [0040]    [0040]FIG. 28 is a plan-style view taken along line  28 - 28  of FIG. 27.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     I. The System Generally  
       [0041]    Referring now to FIG. 1, there is shown a circuit-like conveying system  10  generally which includes a lower or treatment conveying line  12  generally, a lift or transfer mechanism  14  positioned at the end of the lower treatment line to retrieve work pieces therefrom. An upper or drying conveying line  16  is provided to receive treated work pieces from the lift or transfer mechanism  14 . A second lift mechanism  18  is positioned at the end of the drying line  16  to retrieve dried work pieces therefrom and transfer those work pieces to a remote conveyor  20  (see FIG. 12). Untreated work pieces can be moved from the remote conveyor  20  to the entrance for the lower conveyor line  12 . The work pieces are supported on a walking beam assembly  22  which is suspended from a hoist mechanism  24  which cooperates with a travel mechanism  26  that can be indexed forwardly one treatment station or backwardly one treatment station.  
         [0042]    The walking beam assembly  22 , the hoist mechanism  24  and the travel mechanism  26  are interconnected, interrelated and work together to transport, raise and lower work pieces. However, in the description herein the assembly  22  and mechanisms  24  and  26  may be described or referred individually.  
         [0043]    The conveying system  10  includes a stationary support frame  28  which supports the lower conveying line  12 , the upper conveying line  16 , the hoist mechanism  24  and the travel mechanism  26 . As seen in FIG. 2, a work piece such as  30  is positioned above the treatment tank  32  for lowering into the tank  32  and subsequent treatment. It will also be appreciated that the circuit-like conveying system  10  has depth or is three dimensional and accommodates wide work pieces such as  30 . It is also seen that the frame  28  spans a treatment tank such as  32 .  
         [0044]    The operation of the walking beam assembly  22  with respect to the work pieces and the hoist and travel operation is best seen in FIGS.  3 - 11  inclusive. Referring to FIGS. 3, 5,  7 ,  10  and  11 , the beam assembly  22  includes a pair of spaced rails  22 A and  22 B. Associated with each rail are L-shaped hanger engaging members such as  34 . The beam assembly  22  is raised and lowered by a plurality of chains such as  36 . A work piece hanger such as  38  is arranged to support a depending work piece  40  and to engage the hanger engaging member such as  34 . As seen in FIG. 3 work pieces such as  40 ,  42  and  44  can be suspended from the beam assembly  22  over tanks such as  46 ,  48  and  50 . Referring to FIG. 5, the beam assembly  22  is lowered and the work pieces  40 ,  42  and  44  are immersed in tanks  46 ,  48  and  50 . The hangers such as  38  engage and rest on the side of the tanks and the hanger engaging members such as  34  are disengaged from the work pieces and can be moved to a position just below the hanger itself.  
         [0045]    Then the beam  22  is no longer engaged with the hangers and can be moved rearwardly one station as suggested in FIG. 7. Then referring to FIG. 10, the beam  22  is raised and as it is raised it engages the hangers for work pieces  40 ,  42  and  44 . But it will be noted that the rearward hanger engaging member is open (see FIG. 7) and can pick up a new work piece such as  52  in FIG. 10. Then the beam assembly  22  can be moved forwardly as in FIG. 11 thereby indexing the work pieces one station forwardly. It will be noted that each station is spaced the same distance from an adjacent station.  
         [0046]    Referring now to FIG. 4, the hanger  38  supporting the work piece  40  and hanger engaging member bracket  34  are seen. In FIG. 6 the hanger  38  is lowered to rest on the edge of the tank such as  46  and the hanger engaging member  34  is shown in engagement with the hanger and the work piece  40  is shown there below. As seen in FIG. 8, the hanger engaging member  34  is positioned below and disengaged from the hanger  38  and is in position to be moved rearwardly with respect to the tank.  
         [0047]    Referring to FIG. 9, the hanger  38  is shown as a square tube and the hanger engaging member  34  includes an angle iron  34 A which is positioned to engage the hanger  38  and support the same. It is seen that based upon the movement of the beam  22  downwardly, rearwardly, upwardly and forwardly the work pieces are moved in a rectangular pattern so as to move the work piece from one tank to another.  
         [0048]    [0048]FIG. 12 shows the entire circuit-like conveying apparatus  10  in a diagrammatic fashion. There the remote conveyor  20  and the lift mechanism  18  are shown whereby an untreated work piece can be removed from the conveyor  20 , delivered to the lower conveyor line  12  onto the beam assembly  22  so as to be moved to the treatment tanks, then moved to the end of the conveyor  12  where the transfer mechanism  14  can retrieve the work piece and move it upwardly to the drying or upper conveyor  16 . The upper conveyor  16  is a chain-like conveyor line that is positioned within an oven so as to form a drying line. Due to the heat to which the chain is exposed, the chain may lengthen and a take-up or tightening mechanism is provided within the oven so as to adjust the chain.  
         [0049]    Sometimes, it is desirable to prevent a work piece from being immersed or dipped in a particular tank. A hook assembly  50  is provided that is secured to a stationary structure  51  secured to the frame  28  (See FIGS. 1 and 13- 17 ). The hook assembly includes an inverted U-shaped frame  52  that is secured to the stationary structure  51 , two hingedly connected depending hooks  54  and  56  and an actuator bar  58  with an outwardly extending arm  59  that connects the hooks  54  and  56  for joint movement. A pneumatic cylinder  60  is connected at one end to the frame section  52  and at the other end to the actuator bar  58  via the arm  59 . By retracting the piston the bar is rotated and the hooks  54  and  56  raised to a nonengaging position. By extending the piston rod the hooks are rotated to a position so that when the other work pieces are lowered the hooks engage a hangar such as  62  and prevent or restrain the associated work pieces from being lowered. When the beam is raised for movement, the hooks can be rotated to an inoperative position and the previously restrained work piece engages the appropriate support on the beam, the work piece is moved to the next position and can be lowered and raised the other work pieces as seen in FIG. 17.  
       II. The Travel and Hoist Mechanisms and Beam Assembly  
       [0050]    The interrelations and interconnections of the travel and hoist mechanisms  24  and  26  and the beam assembly  22  are seen in FIGS.  18 - 23  inclusive. For purposes of description these mechanisms and assemblies have been described separately.  
         [0051]    Referring first to FIG. 18 the stationary frame  28  includes an end section such as  70  and a pair of rails  72 A and  72 B. The travel mechanism  26  and hoist mechanism  24  are associated with the frame  28 . The beam assembly  22  which supports the various hangers from the hoist mechanism by a plurality of spaced chains such as  74  and  76  and the previously identified chain  36 . The chains are spaced along the length of the beam so as to evenly raise and lower the beam The chains are vertically orientated but trained about a plurality of vertically orientated sprockets such as  78  and  80  which are secured to the travel frame  82  and rotate about a horizontal axis. The chains such as  74  and  76  are trained about the sprockets and are secured at their end to the pull rods  84  and  86 . The pull rods  84  and  86  are operated by a winch or spool  88  about which cables such as  90  and  92  are trained. A cable such as  90  passes through a set of pullies which permit it to retract the pull rods such as  86 . Those pullies include the horizontally arranged pulley  94 , the pulley  96  and the pulley  98 . It will be noted that the end of the cable  90  is grounded or secured to the frame  82  at a point  100  similarly the pullies  94  and  96  are secured to brackets that are also grounded. As seen in FIGS. 19 and 20 by winding the cables  90  and  92  about the drum  88  the pull rods  84  and  86  are retracted and thus draw the frame assembly  22  upwardly through the action of the chains  74  and  76  and other chains which are connected to the pull rod and the assembly such as  102  and  104 . The frame  22  is shown in a lower position in FIG. 20 in which the drum  88  is reversed and the weight of the frame  22  tends to pull the frame downwardly and coacts with the pull rods  84  and  86  and chains  74 ,  76 ,  102  and  104 . The spool  88 , cables  90 ,  92 , rollers  94 ,  96 ,  98  and grounding position  100  can also be seen in FIG. 21.  
         [0052]    Referring to FIG. 22 the hoist mechanism  24 , the travel mechanism  26  and the beam assembly  22  is seen in elevational view and the beam assembly  22  is in the upper position. As indicated above the entire beam assembly  22  and take up apparatus can be indexed one station forwardly or one station rearwardly so as to remove the work pieces from a first tank, raise them and move them to a second tank and then lower them. Referring to FIG. 18, horizontal movement of the beam assembly  22  is controlled by the travel motor  110  drive shafts such as  112  stops  114  and  116  and the traveler or drive mechanism  118  generally (which is also seen in FIG.  23 ). Fundamentally the traveler  118  moves back and forth between the stops  114  and  116  along the chain  120 . It is seen that with the respect to the traveler movement the chain  120  is trained about an idler sprocket  122 , a driven sprocket  124  and another idler sprocket  126 . Thus the motor  110  rotates the drive shaft  112  which causes the sprocket  124  to rotate. The chain  120  is drawn beneath the idler sprocket  122  over the drive sprocket  124  and beneath the idler sprocket  126  to cause the traveler mechanism  118  to move toward one of the stops  114  or  116 . It will be appreciated that when the traveler mechanism moves the hoist mechanisms  24  similarly moves and so does the walking beam assembly  22 . The mechanism is then reversed and the walking beam is moved to the other end at stop  114 . At that point the beam  22  may be raised so as to lift the appropriate hangers and thus the work pieces have been indexed or moved one station forwardly.  
       III. The Transfer or Lift Mechanism  
       [0053]    The transfer or lift mechanism can be seen in FIGS.  24 - 28  inclusive. However, reference is made to FIG. 12 where the lift mechanisms  14  and  18  are shown at either end of the conveyor whereby work pieces can be lifted by a lift mechanism  14  from the end of the lower line  12  to the line  16 . Other lift mechanism can move dried work pieces from the upper line  16  to the remote conveyor  20  and from the remote conveyor  20  untreated pieces can be removed and delivered to the lower conveyor  12 .  
         [0054]    Referring now to FIG. 24, a lift mechanism  150  generally is shown. The lift includes a pair of side posts  152  and  154  which together with cross members  156  and  158  define a frame. Within the frame there is provided a carrier  160  generally which can be moved vertically upwardly or downwardly in the larger frame. A pair of arm assemblies  162  and  164  are secured to the carrier and can move inwardly or outwardly and from one side to the other side of the carrier  160 . The carrier  160  includes an upper cross member  166  and a lower cross member  168 . A pair of vertical members  170  and  172  connect the cross members  166  and  168  and cooperate the posts  152  and  154  which have rails therein.  
         [0055]    The carrier  160  is raised or lowered by a driven chain and counter weight mechanism. The drive motor  174  is connected via a shaft such as  176  to chain drive sprockets  178  and  180  on the opposite sides of the lift. At the top of the lift mechanism idler sprockets  182  and  184  are provided. Drive chains  186  and  188  are trained about the drive sprockets such as  178  and  180 . The chain such as  186  is connected to the carrier  160  by a bar such as  189 . The chain  186  is also connected to the counter weight  190  but on the opposite side of the chain. Thus the motor  174  can drive the chain so that the counter weight  190  moves upwardly and the carrier  160  via bar  189  descends. If the motor  174  is reversed the counter weight  190  is moved downwardly and the carrier  160  is moved upwardly. Each of the arms  162  and  164  are secured to one of the rail-like members  170  and  172  at a position spaced from the top cross member  166  by brackets  171  and  173 . Each of the arms includes a stationary section such as  192  and a telescoping section such as  194 . The telescoping section rides on a I-beam like rail  196  as seen in FIG. 26. On each telescoping section such as  194  a hanger supporting saddle such as  198  or  199  is mounted. The carrier motor  200  and carrier drive shafts  202  and  204  cause the carrier chains  210  and  212  to rotate to cause the telescoping sections of the arms to move inwardly or outwardly as seen in FIG. 24. It will be noted that the carrier cross member  166  is spaced above the connection of the arm to the carrier so as to permit the saddle  198  to move thereunder. Moreover, the entire carrier is sized so as to permit clearance of a work piece suspended from saddles such as  198  and  199 . The carrier chain  212  is connected to the telescoping section  194  by a pinion  213  and rack  214  which cooperate to cause the arm to move laterally inwardly and outwardly.  
         [0056]    The saddle  198  is connected to one end of the telescoping section cable  216 . The cable  216  is trained about the idler  218  and secured to the telescoping section at an end  220 . The saddle  198  is also connected to a second telescoping section cable  222  which is trained about a idler  224  and connected to the telescoping section at end  226 . Thus as the arm moves from one side of the carrier to the other side of the carrier it will be seen that the saddle will move relative to the telescoping section  194  and from one side of the carrier to the other side of the carrier  160 . This is seen in FIG. 27 where the stationary arm  192  and the telescoping arm  194  are shown. In this situation a saddle such as  198  is shown supporting a hanger such as  226  and work piece such as  228 . It will be appreciated that the telescoping section  194  of the arm as well as the hanger  226  and work piece  228  is moved from one side of the post  152  and carrier  160  to the other side (i.e. left to right or vise versa). It is seen that in FIG. 27 the arm can be moved to a lower position or raised to an upper position and the saddle  198 , hanger  226  and work piece  228  can move accordingly.  
       IV. Operation  
       [0057]    In operation an untreated work piece is delivered on a remote conveyor  20  so that a lift mechanism such as  18  can position a telescoping section such as  194  and hanger receiving saddles such as  198  and  199  under the hanger for the work piece and thus remove the work piece from the remote conveyor. The hanger rests on the saddles and the section is retracted under the action of the drive motor  200 . The telescoping sections of the arms are moved to the other side of the lift and in position to be delivered to the treatment conveyor line such as  12 . There the hanger and work piece are deposited on the hanger engaging bracket such as  34  associated with the beam  22  and the untreated pieces are added to the conveyor and moved as shown in FIGS. 3, 5,  7 ,  10  and  11 . The hoist and travel mechanisms  24  and  26  cause the untreated piece to move into and out of the various treatment tanks and to the exit end of the lower line. At the exit end of the lower line  26  a lift mechanism  14  is provided and arms on the lift mechanism are extended and engage the hanger on the appropriate saddles. The arm is then retracted and lifted to the second line such as  16 . There the arms extend and the hanger is deposited on the line  16 . The treated piece is moved along the second or drying line to its exit end. There the lift mechanism  18  extends the arms and engages the hanger using the saddles. The arms are retracted, moved to a lower position, and caused to move to the other side of the lift mechanism and the hanger and work piece are deposited on the remote conveyor  20 . The cycle is then repeated. It will be appreciated the appropriate controls are provided for the operation of the system.  
         [0058]    Numerous changes can be made to the embodiment disclosed herein without departing from the spirit and scope of this invention.