Abstract:
A system for cleaning elongated objects uses a single inclined conveyor with a lower end adjacent a back stop disposed inside a tank containing cleaning solution. The elongated objects pile up between the back stop and the conveyor and a jet manifold sprays a lower side of the pile where pusher flights on the conveyor pick off the objects one at a time. A flip back plate strips the objects from the conveyor to continuously circulate the objects in the cleaning solution from the bottom to the top of the pile. The plate is retracted to allow the conveyor to deliver the objects to a rinse water basin where the clean objects are rinsed and then removed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not applicable.  
       STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable.  
       BACKGROUND OF THE INVENTION  
       [0003]     1. Field of the Invention  
         [0004]     The present invention relates to a system for washing elongated objects. More particularly, it relates to a system for washing sticks or rods which have been used for cooking and/or chilling food products.  
         [0005]     2. Background of the Art  
         [0006]     In the processed meats industry, products such as hotdogs and sausages are typically suspended in link form from stainless steel sticks or rods for cooking and chilling. The sticks are usually three to four feet long and are either tubular or have a V-shaped cross-section. Following removal of the product from the sticks, the sticks must be cleaned before being reused.  
         [0007]     Typically, such sticks are cleaned using large drum-type washing machines. Such washers usually consist of a round or octagonal shaped drum with a side access door. The drum can be supported in a vessel by a drive shaft. The sticks are manually placed in the drum and the drum is rotated in a cleaning solution. This produces some tumbling action between the sticks but tends to confine and block cleaning solution from effectively penetrating the core of the stick load in the drum. Further, the sticks with the V-shaped cross-section are prone to bunching and nesting which limits any mixing or migration of the sticks through the drum. Also, cleaning solution must be dumped after the wash cycle to allow refilling the unit with rinse water.  
         [0008]     Another prior art apparatus for treating rods and pipes is disclosed in J. Moltrup, U.S. Pat. No. 1,393,633. The system disclosed in this patent includes a machine divided into separate pickling and washing compartments. The rods are organized into bundles or bunches and each bundle is inserted into a carrier. The carriers are placed on a runway which conveys the carrier into each compartment. As each carrier reaches the lower end of the runway, it is caught by a conveyor with flights and conveyed out of the first compartment. The carrier is passed through subsequent compartments, each with its own conveyor. One drawback of this system is the need for multiple conveyor assemblies. Another problem is that the rods must be placed in individual carriers and must be moved therefrom after exiting the apparatus. Also, there is no provision in the individual carriers for insuring that the rods and sticks are well mixed.  
         [0009]     Another washing apparatus is disclosed in W. Morgan, U.S. Pat. No. 1,751,838. This apparatus is used for preparing cane stalks. The cleaning tank is provided with a hopper having inclined ends which direct the cane stalks onto a looped-shaped conveyor located adjacent to the bottom of the hopper. Another conveyor which shares a shaft with the loop-shaped conveyor conveys the cane stalks out of the hopper. Each of the conveyors is provided with a series of fingers which positively moves the cane stalks from the infeed of the hopper to the outfeed of the hopper. Like the previously described prior art washer, this system requires multiple conveyors. Another drawback of this system is that the cane stalks can short circuit the desired tumbling action in the circular conveyor by being removed too soon by the outfeed conveyor.  
         [0010]     Another washing apparatus is disclosed in Ransley et al., U.S. Pat. No. 5,778,907, which is assigned to the assignee of the present invention and hereby incorporated by reference as though fully set forth herein. This patent discloses a conveyor washer specifically designed to improve the efficiency of washing the sticks or rods used by the food processing industry. Here, two conveyors are used, each with two spaced apart continuous loop chains. An infeed conveyor slopes down from one end of the tank toward the bottom of the tank where an outfeed conveyor slopes upwardly toward the other end of the tank. The conveyors run simultaneously and are positioned at a prescribed included angle so that the infeed conveyor drives the pile of sticks toward the outfeed conveyor which has pusher flights that carrying the sticks upward individually. A flip back plate strips the sticks from the outfeed conveyor so that the objects circulate in the wash tank. When the wash cycle is complete, the flip back plate can be retracted so the sticks can be conveyed by the outfeed conveyor to a rinse tank. This system provides for efficient loading and unloading of the sticks as well as promotes effectively cleaning by separating and recirculating the sticks during the wash cycle. However, the disclosed system requires two separate conveyors, like the other prior art washers described above, and must be placed relative to each other at the proper angle. If the angle is too large, the infeed conveyor will not effectively deliver the sticks to the outfeed conveyor and if the angle is to small the sticks may become lodged and jam one or both of the conveyors, particularly since the infeed and outfeed conveyors act on the stick pile in opposite directions. This two conveyor system thus adds to the complexity, cost and maintenance of the washer.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention provides a washing system that effectively cleans elongated objects without the stagnant zones common in the prior art. It provides efficient loading and unloading of the elongated objects and allows the cleaning solution to be reused for subsequent loads. The present invention provides such a system with reduced cost and complexity compared to multi-conveyor systems.  
         [0012]     In particular, one aspect of the present invention provides an apparatus for cleaning elongated objects having a cleaning tank, of the size necessary to hold the elongated objects in a cleaning solution, defining a feed end and an exit end formed by a top, a bottom and side walls and containing a back stop and an inclined conveyor. The back stop is mounted inside the tank at the feed end and extends in the direction between the top and bottom of the tank. The conveyor is mounted inside the tank with its lower end adjacent the back stop and so it slopes upwardly in the direction from the tank bottom to the exit end so as to convey the elongated objects from the feed end to the exit end.  
         [0013]     During a cleaning cycle several elongated objects are loaded into the tank. The elongated objects pile up between the back stop and the conveyor. The conveyor strips off the lower, adjacent layer of elongated objects in the pile one at a time and circulates them through the cleaning solution. The elongated objects are thus pulled from the bottom side of the pile and returned to the top side. While piled and as they are beginning up the conveyor, a jet manifold provides a pressure spray that agitates and cleans the elongated objects. The weight of the pile holds the sprayed elongated objects down somewhat so that a forceful spray can be directed at the elongated objects without them being pushed away from the conveyor. While the true dynamics of the pile of elongated objects is somewhat unclear, the inventors have realized that it is important for the elongated objects to pile up as well as be circulated from bottom to top of the pile in order to achieve proper cleaning. The angle of incline of the conveyor and the included angle between the conveyor and the back stop are critical to avoid pockets of stagnation and achieve proper circulation of all the elongated objects.  
         [0014]     Preferably, the back stop is essentially perpendicular and the conveyor is essentially at a 45° angle to the tank bottom. The back stop and conveyor thus extend along intersecting planes defining an angular section therebetween. Preferably, the included angle is between about 35° to about 60°, or more preferably of about 40° to about 50°, and even more preferably of about 45°, with the small angle between the conveyor and the tank bottom being preferably no less than 35°.  
         [0015]     In other preferred forms, the tank includes separate wash and rinse basins and utilizes a single overflow sump, disposed between the basins, to limit disparate maximum water levels in each. A load ramp is mounted inside the tank at the feed end and slopes downwardly so that objects can readily slide down between the back stop and the conveyor. The conveyor itself preferably has two spaced apart chains. The chains include sets of aligned pusher flights extending from the conveyor at an angle. A flip back plate is mounted between the chains of the conveyor and is movable between a retracted position and an extended position. In the extended position, the plate is above the conveyor, and preferably, above a maximum fill level of the cleaning solution, which is regulated by an overflow.  
         [0016]     In another aspect the invention provides a method of cleaning elongated objects comprising: feeding the elongated objects to the above described apparatus; operating the conveyor with the plate in the extended position for a predetermined time; and delivering the elongated objects to a rinse tank at the exit end of the tank by placing the plate in the retracted position; and removing the elongated objects from the rinse tank.  
         [0017]     The objects and advantages of the present invention will be apparent from the description which follows. The following description is merely of a preferred embodiment. Thus, the claims should be looked to in order to understand the full scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a side elevational view of the single conveyor washer apparatus according to the present invention;  
         [0019]      FIG. 2  is a top plan view thereof;  
         [0020]      FIG. 3  is another side elevational view thereof opposite the side shown in  FIG. 1 ;  
         [0021]      FIG. 4  is an exit end view thereof;  
         [0022]      FIG. 5  is a typical longitudinal cross-sectional view thereof;  
         [0023]      FIG. 6  is a partial cross-sectional view thereof taken along the line  6 - 6  of  FIG. 5 ;  
         [0024]      FIG. 7  is a fragmentary enlarged detail of the flip back plate assembly; and  
         [0025]      FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 6 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]     The present invention provides an apparatus and method of washing elongated objects, such as tubular and V-shaped food processing sticks, that is an improvement over the drum and multi-conveyor type machines of the prior art. The washer of the present invention can clean and rinse the objects as well as or better than prior art machines with less complex sub-assemblies, thereby saving cost and reducing maintenance.  
         [0027]     Referring to  FIGS. 1-5 , in this washer  10 , a tank vessel  12  defining a top, a bottom and side walls, in general constructed of 304 stainless steel, contains a single conveyor  14  that circulates the elongated objects (“sticks”)  16  loaded into the vessel  12  from an open feed end  18  within a wash basin  20  for a period of time before carrying the objects to a shallower rinse basin  22  at an open exit end  24 . The opening at the exit end  24  is preferably shielded by a strip curtain  25  depending from the top of the vessel  12  to retain heat and steam during the wash and rinse cycles. If desired, a second curtain (not shown) could be similarly mounted at the feed end  18 . The vessel  12  is designed to accommodate sticks  16  having a typical length of 36-48 inches long. However, the apparatus can be modified in obvious ways to accommodate sticks of any size. The top of the washer  10  is equipped with a cover  26  which may be removed for easy access to the internals of the vessel  12 . The level of the cleaning solution in the wash basin  20  and the level of rinse water in the rinse basin  22  is maintained by respective wash  28  and rinse  30  fill nozzles and an overflow sump  32  formed between the basins  20  and  22  and drained through a drain  34  leading to an exterior drain (not shown). If desired, the wash basin  20  may be drained via drain  36  (see  FIG. 2 ). Sticks  16  are discharged into the rinse basin  22  by falling off the conveyor  14  and onto a rinse rack  40 , which sits on the bottom of the rinse basin  22 . The rinse basin has a drain  42  at its bottom. A removable perforated stainless steel filter  44  is disposed inside of a box  46  at the exterior feed end of the vessel  12 . The interior of the box  46  is in communication with the interior of the wash basin  20  by a triangular cut out in the side of the vessel  12 . The filtered water is then pumped back into the wash basin  20  via line  48 . The filter  44  can be accessed for cleaning via removable lid  50 , and the box  46  can be drained by opening drain valve  52 . The filter  44  and the bottoms of the box  46  and the wash basin  20  are sloped to facilitate filtering and draining, respectively. Also, the bottoms of the rinse basin  22  and the overflow sump  32  are also sloped toward their respective drains.  
         [0028]     Referring to  FIGS. 5 and 8 , proper agitation and circulation of the objects  16  using only a single conveyor  14  is facilitated by a planar back stop  54  extending within the wash basin  20 . The back stop  54  is preferably formed of a single stainless steel panel that bends to also define a load ramp  56 , sloping downwardly at about a 45° angle from the open feed end of the vessel  12  to facilitate loading of the sticks  16 . Below the bend, the back stop  54  extends straight down to be essentially vertical and perpendicular to the bottom of the vessel  12 . The back stop  54  has a cut-out bottom side through which the lower end of the conveyor  14  protrudes.  
         [0029]     Referring to  FIGS. 1, 5  and  6 , the conveyor  14  includes a set of two closed loop conveyor chains  58  spaced apart and installed around sprockets  60  preferably mounted via adjustable bearings to a drive  62  and follower  64  conveyor shafts. The conveyor chains  58  are preferably polymeric but may be any acceptable material which is compatible with the cleaning solution. Each chain  58  has pusher flights  66  which act to engage the sticks  16  and both circulate them within the cleaning solution in the wash basin  20  and move them one at a time from the wash basin  20  to the rinse basin  22 . Each chain  58  is supported by a channel  68  which is in turn supported by an angle member  70  and a jet manifold  72 , which is part of the liquid circulation system described below. The channels  68  preferably include one or more slots or openings  69  for the cleaning solution to pass through. If necessary, an adjustable tensioner (not shown) can be included for each chain. Such tensioners can be in the form of spring loaded arms with a roller in contact with its respective chain, or the tensioners can have adjustable arms secured with a nut and bolt, as is known in the art. The conveyor  14  is propelled by applying power to the drive shaft  62  via motor  74  (see  FIG. 2 ) mounted at the exterior of the vessel  12 , which preferably has a variable speed so that the conveyor speed may be adjusted to suit the particular washing application. Operation of the motor  74  is controlled by a logic controller (not shown) contained in an electronics cabinet  76  mounted to the exterior of the vessel  12  (see  FIGS. 2 and 4 ). The control cabinet  76  houses other the electrical components associated with the conveyor shaft motor, a pump motor and other electrical subsystems.  
         [0030]     The conveyor shafts are preferably arranged so that the plane of the conveyor  14  and the back stop  54  form an angular section having an included angle of about 35° to about 60°. More preferred is an angle at or about has an angle of about 45°. And, preferably the conveyor  14  is about 35° to 50° degrees from the horizon, or the bottom of the vessel  12 , the most preferred being about 45°. When the included angle between the back stop  54  and the conveyor  14  is significantly less than about 45°, the space for the stick pile is reduced thereby, not only making the pile smaller, but also making it narrower and taller and therefore less suitable for circulating the sticks properly. When the included angle is significantly more than about 45°, then the pile flattens too much and can cause the sticks to at the back of the pile (near the back stop  54 ) to stagnate rather than be circulated by the conveyor. Also, the reduction in depth of the stick pile diminishes the ability of the pile to hold the sticks on the conveyor against the force of the water from the jet manifold. Furthermore, the flattened stick pile may begin to move up the conveyor  14  collectively, rather than as individual sticks, thereby causing erratic mixing of the sticks and potential jamming at the flip back plate  78 . When the angle of inclination of the conveyor  14  is significantly less than about 45°, such as below 35°, the sticks ejected from the conveyor  14  by the flip back plate  78  may fall short and land on the conveyor  14  rather than at the back of the pile as preferred, thus also causing erratic circulation and cleaning of the sticks.  
         [0031]     Previously, it was thought that a separate infeed feed conveyor was necessary to pull the sticks  16  ejected from the conveyor  14  by the flip back plate  78  down toward the bottom the pile to ensure the sticks did not stagnate at the top of the pile. However, the inventors of the present invention have determined through empirical study that proper circulation of the sticks  16  could be achieved using only a single conveyor in combination with the back stop  54  of the disclosed configuration and location such that all of the sticks  16  could be adequately de-nested and cycled through the cleaning solution prior to rinsing.  
         [0032]     Referring now to  FIGS. 5-7 , a movable flip back plate  78  is used to eject the sticks from the conveyor  14  during the washing cycle. The flip back plate  78  has a bent upper lip  80  to prevent the sticks  16  from riding up over the flip back plate  78 . The flip back plate  78  is mounted via linkage to a flip back plate shaft  82 , which is bounded by the chains  58  of the conveyor  14 . Specifically, a handle  84  is fixedly connected to a crank arm  86  which is in turn pivotally connected to a connecting link  88  fixedly attached the flip back plate  78 . Rotating the handle  84  (clockwise in  FIG. 7 ) until the arm  86  hits angle  70  moves the flip back plate  78  to the extended position in which it protrudes above an upper plane formed by the chains  58  of the conveyor  14 . In this position, the pivot point of the arm  86  and the arm  88  is located above a centerline  91  connecting the axis of the flip back plate shaft  82  and the pivot axis of the handle  84  such that the arm  86  and link  88  resist incidental retraction of the flip back plate  78  from contact with the sticks  16 . In the retracted position, in which further rotation is prevented by contact of an upper part of the flip back plate  78  against angle  70 , the flip back plate  78  is just below the upper plane of the conveyor chains  58 . A lower bent down edge  89  is welded to another shaft  93  rotatably mounted to the conveyor support frame. The angle between the pusher flights  66  and the extended flip back plate  78  can be of any size as long as the sticks can be efficiently peeled off the conveyor  14  without the sticks hopping over the flip back plate  78 . Preferably, the flip back plate  78  is essentially vertical when deployed and the face of the pusher flight  66  is beveled at about 30° so that the included angle is about 75°. These parameters have been determined to provide suitable operation without jamming of the sticks.  
         [0033]     Referring again to  FIGS. 1 and 2 , the circulation system of the washer  10  includes a pump  90  located in the dry part of the vessel  12  beneath the bottom wall of the rinse basin  22 . The pump  90  is connected by the suction line  48  to the exit of the strainer box  46  and by a discharge line  92  to the elongated jet manifold  72 . The jet manifold  72  is bounded by the conveyor chains  58  and has a plurality of openings directed at the angular section between the conveyor  14  and the back stop  54 . The jet manifold  72  directly impinges the cleaning solution near the lower adjacent side of the stick pile. Directing the jetstream near the bottom sticks provides for more effective cleaning because the weight of the pile of sticks holds the sticks against the force of the spray thereby allowing them to be sprayed forcefully without being pushed away from the conveyor.  
         [0034]     Referring to  FIGS. 2-4 , a thermometer (not shown) is provided on the side of the vessel  12  which directly measures the temperature of the cleaning solution in the wash basin  20 . Temperature control of the cleaning solution is accomplished by thermowell  102  which is operably connected to steam regulator  104 . When the temperature of the cleaning solution falls below the desired set point, the steam regulator  104  will open allowing steam to be introduced into a steam mixer  106  mounted inside the vessel  12  and thereby heat the cleaning solution.  
         [0035]     In use, the sticks  16  are loaded into vessel  12  through the open feed end  18 . If not already done, the wash  20  and rinse  22  basins are filled with water and liquid cleanser is injected into the wash basin  20  through an injection port in a side wall of the vessel  12 . Based on the temperature of the water, steam may also be injected into the wash basin  20 . During operation of a wash cycle, the conveyor motor  74  is energized to turn the chains  58 . The pusher flights  66  on the chains  58  pull sticks  16  off the bottom of the pile and conveys them upwards until they reach the flip back plate  78 , which is placed in the extended position by manually rotating the handle  84 . The extended flip back plate  78  peels the sticks  16  off the conveyor  14  and directs them back through the cleansing solution toward the back stop  54  and to the top of the pile of sticks  16  between the back stop  54  and the conveyer  14 . The shearing action at the bottom of the pile tends to separate and de-nest the sticks. At the end of the timed wash cycle, the flip back plate  78  is retracted, by rotating the handle  84  in the opposite direction, and the sticks are conveyed out of the wash basin  20  by the conveyor  14  into the rinse basin  22 . When all of the sticks have been transferred from the wash basin  20 , the conveyor  14  is stopped. The washed and rinsed sticks are then removed from the vessel  12  by lifting the rinse rack  40  through the open exit end  24 . Preferably, the cleaning solution is saved for the next batch of sticks. Overflowing wash or rinse water exits the vessel through the overflow sump  32  and out through its drain. Preferably, the wash basin  20  is topped up with water and possibly additional cleanser and the rinse basin  22  is drained and refilled prior to the next wash cycle.  
         [0036]     An illustrative embodiment of the present invention has been described above in detail. However, the invention should not be limited to the described embodiment since many modifications and variations to the preferred embodiment, apparent to those skilled in the art, will be within the spirit and scope of the invention. For example, the washer could be supplied with an inlet hopper and inlet hopper door assembly (not shown) to better facilitate loading of the sticks. Also, the washer preferably includes a close out assembly having plates mounted to the vessel so as to close off the space between the chains of the conveyor to reduce the likelihood for sticks passing between the chains and beneath the conveyor. Therefore, to ascertain the full scope of the invention, the following claims should be referenced.