Patent Abstract:
A system and method for unloading a viscous product from a bag constrained by a bin where movable scrapers are utilized to increase the amount of product evacuated from the bag, to prevent damage to the bag containing the product, and to ease removal of the pump after pumping is complete by breaking the vacuum created during pumping.

Full Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a system for evacuating a viscous product from within a plastic bag that is constrained by a bin. More specifically, the present invention relates to such a system that includes adjustable scrapers. The adjustable scrapers reduce the risk of harm to the plastic bag and once pumping is complete, ease removal from the plastic bag of the plate carrying the scrapers and the pumps. 
   Bin unloading systems are customarily used in the food processing and pharmaceutical industries. Viscous products such as tomato paste, icing and medical preparations are provided to manufacturers in bulk in large plastic bags which are placed within bins and subsequently unloaded by floating a platform generally referred to as a follower plate on the surface of the product and pumping the product up through the follower plate. 
   It is important that the evacuation of the product from the bag be complete to avoid waste. Viscous products often adhere to the bag which may collapse as the product is evacuated to overlie pockets of the product. Since gravity forces the bag to conform to the size of the bin, it is known to attach scrapers to the follower plate which extend laterally into close proximity to the bin supported bag wall to remove product clinging thereto as the product is evacuated. 
   However, removal of the follower plate from the unloaded bag is often problematical. The bag may collapse over the follower plate and the laterally extending scrapers may damage the bag as the follower plate is withdrawn from the collapsed bag. In addition, the upward scraping of the bag may cause product to be deposited on the top of the follower plate and/or the floor in the area around the bin, requiring cleaning to avoid health hazards and safety issues. Moreover, the product may create a seal between the scrapers and the bin supported bag, and withdrawal of the follower plate may create a vacuum which resists the withdrawal of the follower plate from the bag and/or pulls the bag from the bin as the follower plate is withdrawn. 
   One known system for bin unloading injects air between the plate and the bag during withdrawal of the plate to keep the bag within the bin. While the injection of air facilitates to some extent the removal of the plate from the bag; it does not address the upward scraping and/or bag damage issues. Moreover, injecting air between the plate often may not be acceptable to the food processors for other reasons. 
   Another known system utilizes inflatable scrapers to assist in unloading the product from the bag. Accordingly, when the plate is lowered the scrapers are inflated so that they contact the interior walls of the bag. Before the plate is withdrawn the scrapers are deflated so that they are no longer in contact with the bag, preventing the bag from being re-scraped when the plate is removed and eliminating the vacuum created during pumping. Inflated scrapers are generally not rigid enough to adequately scrape the bag and the scrapers themselves may be punctured during the scraping operation resulting in delay and down time for replacement. 
   Accordingly, it is an object of the present invention to obviate many of the above problems in known systems and to provide a novel system and method for unloading a viscous product contained within a bag constrained by a bin. 
   One embodiment of the present invention avoids the problems of the known systems by mounting movable scrapers at the edges of the plate selectively extended to remove product adhering to the interior surfaces of the bag when the plate is lowered and retracted out of contact with the interior of the bag upon withdrawal of the plate. 
   It is another object of the present invention to provide a novel bin unloading apparatus and method that reduces risk of injury to the bag containing a viscous product. 
   It is yet another object of the present invention to provide a novel bin unloading apparatus and method that eliminates the vacuum created during pumping and eases removal of a follower plate from the bag containing a viscous product. 
   It is still another object of the present invention to provide a novel bin unloading apparatus and method with scrapers that can be extended or retracted to vary the lateral distance between the scrapers and the bin. 
   It is a further object of the present invention to provide a novel bin unloading apparatus and method with scrapers that can be extended or retracted to laterally center a follower plate within the bag containing a viscous product that is constrained by a bin. 
   It is an additional object of the present invention to provide a novel method for maintaining a clean work area when unloading a viscous product from a bag constrained by a bin. 
   These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an elevation in cross-section illustrating a bin unloading system in accordance with one embodiment of the present invention. 
       FIG. 2  is an illustration of a spring biased scraper which may be used with the embodiment of FIG.  1 . 
       FIG. 3  is an illustration of a scraper that has been retracted so as not to extend beyond the lateral edge of the plate. 
       FIG. 4  is an overhead view of one embodiment of the present invention with the scrapers extended laterally. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Like numerals represent like components throughout the several drawings. 
   Referring to  FIG. 1 , a bin unloading system  10  includes a bin  12  for constraining a bag  14  that contains a viscous product. The bin may be constructed of any material, i.e., plastic, metal or wood, that is rigid enough to withstand the pressure created when the product is pumped out of the bag  14  and to withstand the forces exerted by the weight of the product and the lateral force of the scrapers when wiping the interior of the bag  14 . 
   Continuing with  FIG. 1 , the bin unloading system  10  includes a follower plate  16  of any suitable conventional material. As depicted, the plate  16  is in a rest position above the bin  12  either before or after pumping has occurred. During pumping, the follower plate  16  is lowered into the bag  14  and the pumps  18  carried by the plate  16  withdraw a viscous product out of the bag  14  through the follower plate  16 . Ensuring that the maximum amount of product is evacuated from the bag scrapers  20 A,  20 B are provided to wipe the interior sides of the bag removing any product clinging thereto as the plate  16  is lowered within the bag  14 . 
   Each scraper  20 A,  20 B may include a flexible blade  22  that contacts the interior of the bag  14  to remove any product adhering thereto. The flexible blade  22  may be made from rubber or any other conventional wiper blade material. Any means for attaching the blade  22  to the follower plate  16  may include a hinge  24  or any other suitable conventional component that permits the position of blade  22  in relation to the bag and the follower plate to be adjusted. Any actual change in the position of the scraper  22  is accomplished with an adjustment means  26  such as an air piston or the like for adjusting and maintaining the position of the scraper. 
   Still referring to  FIG. 1 , the blade  22  may adjusted to be in various other positions that are not shown. The flexible blade  22  of scraper  20 A is positioned so that the blade  22  extends past the lateral edge  17  of the follower plate  16  during pumping and so that the blade  22  does not extend past the lateral edge  17  of the plate  16  upon withdrawal or initial insertion into the bag. When extended into contact with the interior sides of the bag  14 , the blade  22  will scrape the bag removing any product adhering thereto when the follower plate  16  is lowered within the bag  14 . By scraping the bag  14 , the amount of viscous product which may be unloaded from the bag is increased. Note that the selective extension of the blades serves to keep the follower plate centered. 
   In  FIG. 2 , the scraper  20  includes a tension spring  30  extending between the plate  16  and the flexible blade  22 . When the plate  16  is lowered into the bag  14 , the viscous fluid exerts an upward force against the blade  22  that may prevent continuous contact between the blade  22  and the interior sides of the bag  14 . Additionally, as the blade  22  scrapes the interior surface of the bag  14  friction exerts an upward force on the blade  22  that may also prevent continuous contact between the blade  22  and the interior sides of the bag  14 . Without the requisite contact between the blade  22  and the bag  14 , adequate evacuation of the product cannot be achieved. In order to counter the upward forces a spring  30  or other suitable resilient member may be included to provide a downward force on the blade  22  to ensure continuous contact between the blade  22  and the interior of the bag  14  throughout evacuation of the viscous product. The spring  30  may also assist in properly locating the plate  16  on the surface of the viscous product within the bag  14 . 
   As shown in  FIG. 3 , the scraper that has been retracted so as not to extend beyond the lateral edge of the plate prevents contact of the blade  22  with the interior of the bag  14 . Once pumping is complete, contact between the interior sides of the bag  14  and the blade  22  may thus be eliminated to eliminate any vacuum created during pumping. This allows the plate  16  to be removed from within the bag  14  without the re-scraping and possibly damaging the bag  14 . It also permits the follower plate  16  to be removed from the bag  14  without withdrawing the bag from the bin. 
   While preferred embodiments of the present invention have been described, it is to be understood that the embodiments described are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalence, many variations and modification naturally occurring to those of skill in the art from a perusal hereof.

Technology Classification (CPC): 1