Patent Publication Number: US-9840374-B2

Title: Self-biasing scraper for a conveyor belt

Description:
RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Patent Application No. 62/185,845, filed Jun. 29, 2015 and entitled “Self-Biasing Scraper for a Conveyor Belt”, the contents of which are herein incorporated by reference. 
    
    
     BACKGROUND 
     The invention relates generally a belt scraper for cleaning a conveyor belt. 
     Conveyor belt systems typically include a cleaning system for removing debris and other materials from the outer surface of the conveyor belt. For example, scraper blades in contact with the belt surface may be used to remove material deposits from the belt surface. A typical scraper has a metallic or flexible plastic, e.g., polyurethane, body that is mounted on a support shaft that spans a conveyor belt and that usually includes a spring-based tensioner that biases the scraper into engagement with the conveyor belt to allow them to scrape leavings off of the belt and yet resiliently shift away from the belt when surface irregularities on the belt are encountered. For a positively-driven, low-tension conveyor belt such as the ThermoDrive® belt available from Intralox, L.L.C., a separate position limiter system is usually required in the vicinity of the cleaning system for proper belt function, increasing the number of components required in the limited space surrounding the conveyor. 
     SUMMARY 
     The present invention provides a self-biasing conveyor belt scraper for removing debris and other materials from the outer surface of the conveyor belt, which also functions as a position limiter at the same time when used with a positively driven, low tension conveyor belt. The self-biasing scraper includes a base that contacts the conveyor belt at a first location and a tapering scraper tip extending from the base for contacting the conveyor belt in a second location. When the conveyor belt runs, the conveyor belt pushes against the base to bias the tapering scraper tip into contact with the conveyor belt. 
     According to one aspect, a scraper for a conveyor belt comprises a base and a tapering scraper tip. The base includes an opening for receiving a shaft and having an upper surface for contacting the conveyor belt in a first location. The tapering scraper tip extends from the base and contacts the conveyor belt in a second location. 
     According to another aspect, a conveyor comprises a conveyor belt trained around at least a first reversing element and a second reversing element, a shaft mounted below the second reversing element, and a self-biasing scraper mounted on the shaft. The self-biasing scraper comprises a base having an outer surface and a tapering scraper tip extending from the base. The outer surface contacts the outer side of the conveyor belt at a first location and the tapering scraper tip contacts the outer side of the conveyor belt at a second location. 
     According to another aspect, a method of scraping debris from a conveyor belt trained around a reversing element comprises the steps of mounting self-biasing scraper to a shaft disposed below the reversing element such that a base of the self-biasing scraper contacts the conveyor belt in a first location and driving the conveyor belt such that the conveyor belt pushes against the base of the self-biasing scraper in the first location to push a tip of the self-biasing scraper into contact with the conveyor belt at a second location. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These features and aspects of the invention, as well as its advantages, are described in more detail in the following description, appended claims, and accompanying drawings, in which: 
         FIG. 1A  is a side view of an end of a conveyor including a self-biasing scraper according to an embodiment of the invention; 
         FIG. 1B  is an isometric view of the conveyor end of  FIG. 1A ; 
         FIG. 2A  is a side view of the self-biasing scraper of  FIG. 1A ; 
         FIG. 2B  is an isometric view of the self-biasing scraper of  FIG. 1A ; 
         FIG. 2C  is a top view of the self-biasing scraper of  FIG. 1A ; 
         FIG. 3A  is a side view of an end of a conveyor including a self-biasing scraper including a counter weight according to another embodiment of the invention; 
         FIG. 3B  is an isometric view of the conveyor end of  FIG. 3A ; 
         FIG. 3C  is another view of the conveyor end of  FIG. 3A ; 
         FIG. 4A  is a side view of the self-biasing scraper of  FIG. 3A ; 
         FIG. 4B  is a top isometric view of the self-biasing scraper of  FIG. 3A   
         FIG. 5  shows another embodiment of a self-biasing scraper including a channel for receiving a counter weight; 
         FIG. 6A  is a side view of another embodiment of a self-biasing scraper including an integral counter weight; 
         FIG. 6B  is an isometric view of the self-biasing scraper of  FIG. 6A ; 
         FIG. 7A  is an isometric view of a self-biasing scraper including openings for receiving position limiters according to another embodiment of the invention; 
         FIG. 7B  is a side view of the self-biasing scraper of  FIG. 7A ; 
         FIG. 8A  shows the self-biasing scraper of  FIGS. 7A and 7B  with assembled position limiters; 
         FIG. 8B  is a bottom view of the self-biasing scraper of  FIG. 8A ; 
         FIG. 8C  is a side view of the self-biasing scraper of  FIG. 8A ; 
         FIG. 8D  is a side view of the self-biasing scraper of  FIG. 8A  with the scraper rotated on the shaft without interference with the position limiters; 
         FIG. 9A  is a side view of another embodiment of a self-biasing scraper; and 
         FIG. 9B  is an isometric view of the self-biasing scraper of  FIG. 9A . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention provides a self-biasing conveyor belt scraper for removing product and-or debris from a conveyor belt. The invention will be described relative to certain illustrative embodiments, though the invention is not limited to the embodiments described herein. 
       FIGS. 1A and 1B  show a discharge end of a conveyor belt  12  trained around a reversing element, shown as a sprocket  14 . The reversing element can be any suitable belt-guiding member, including a roller. The illustrative conveyor belt  12  comprises a positively-driven, low tension conveyor belt, such as the ThermoDrive® belt available from Intralox, L.L.C., the Cleandrive positive drive belt available from Habasit AG, the Gates Mectrol PosiClean® positive drive belt available from Gates Mectrol, the Volta SuperDrive™ and other positive drive belts available from Volta Belting and other positively-driven, low tension conveyor belts known in the art. The invention is not limited to these belts, and may be implemented with any suitable positive-drive, low tension conveyor belt as well as any tensioned flat belt. The illustrative conveyor belt has a smooth outer surface substantially free of discontinuities and an inner surface with a plurality of drive elements, shown as teeth  13 , at a given belt pitch. The conveyor belt  12  conveys products along a carryway and returns along a returnway below the carryway. The illustrative sprocket  14  comprises a plurality of drive elements, shown as teeth  15 , for engaging drive elements  13  on the conveyor belt  12 . The sprocket  14  is mounted on a rotatable shaft  16 . The sprocket  14  may be a drive sprocket or an idle sprocket. Other suitable means for driving the belt may be used. As product approaches the end of the carryway, the conveyor belt  12  reverses direction, guided by the sprocket  14 . 
     A self-biasing scraper  20  is biased into contact with the conveyor belt  12 . The scraper  20  removes material from the outer surface of the conveyor belt as the belt moves over the sprocket or other belt guiding member. The self-biasing scraper  20  is mounted on a shaft  18  below the sprocket  14 . Referring to  FIGS. 2A-2C , the self-biasing scraper  20  comprises a base  22  having a central opening  24  for receiving the shaft  18 . The illustrative base  22  is cylindrical or tubular, though the invention is not so limited. Alternatively, the base can be open and clamp onto the shaft  18  as in  FIGS. 9A-9B . The base  22  forms a top surface  26  that contacts the conveyor belt outer surface at bottom location  50 , which is shown as 180° from the top (0°) of the sprocket, though the invention is not limited to be positioned at this location. In one embodiment, the top surface  26  is formed by a protrusion, bulge or other feature on the base  22  and can be concave, convex, or other complex geometries deemed appropriate. 
     A tapering scraper tip  30  extends from the base  22 . The tapering scraper tip forms a scraping edge  32  that contacts the outer surface of the conveyor belt  12  at a second location  52  to scrap away product and debris. The illustrative second location  52  is about 135° from the top of the sprocket, though the invention is not so limited and the second point of contact can be any suitable location on the belt. The tip  30  includes a bar portion  34  extending at an angle from the base  22  towards the front of the sprocket  14 . The illustrative bar portion has a substantially consistent cross-section, though the invention is not so limited. The illustrative bar portion  34  extends perpendicular to the base  22 , but the invention is not so limited, and the angle of the bar portion relative to the base can be any suitable angle. The end  36  of the bar portion  34  bends slightly upwards and tapers to form the scraping edge  32 . The illustrative scraping edge is linear, though alternatively, the scraping edge can be nonlinear. 
     Referring back to  FIG. 1A , the self-biasing scraper  20  is mounted on the shaft  18  so that the top surface  26  contacts the outer surface of the conveyor belt  12  at location  50 . As the conveyor belt  12  moves in direction  19 , the contact between the outer surface of the conveyor belt  12  and the top surface  26  causes the base  22  to rotate on the shaft  18  in direction  38 , which pushes the scraping edge  32  into contact with the outer surface of the conveyor belt at the second location  52 . As the scraper tip wears out, the scraper  20  self-adjusts to maintain contact with the conveyor belt outer surface at location  52 . The drag by the belt sliding over the base  22  provides uniform tension, ensuring that the scraper tip  32  conforms to the belt surface for better scraping performance. 
     The illustrative scraper tip  30  is integral with the base  22 , but the invention is not so limited, and the scraper tip or a portion thereof may be removable and—or replaceable. The scraper tip  30  may also or alternatively be formed of a different material than the base, or coated in a different material to optimize scraping. 
     The base portion  22  may function as a position limiter to ensure engagement of a driven tooth with a sprocket. Position limiters, such as described in U.S. Pat. No. 7,850,562, the contents of which are incorporated herein by reference, may be used in low tension, positive drive belting systems to ensure proper engagement of the belt and drive sprocket by controlling the position of the belt during the drive tooth hand-off process. Preferably, the sprocket effectively drives only one tooth of the sprocket at a time, except for the duration in which a leading driven tooth disengages from the sprocket and hands off to the immediately trailing tooth as the trailing tooth becomes the leading driven tooth. The use of a position limiter helps control this handoff by ensuring proper engagement between the belt and corresponding sprocket. The base portion  22  is placed a select distance away from the sprocket  14  to force the driven tooth into the sprocket pocket and into engagement with the driver elements of the sprocket. 
     In one embodiment, the position of the shaft  18  may be variable to ensure proper engagement and positioning of the self-biasing scraper  20 . 
     The self-biasing scraper  20  is not limited to a round base as shown. The base portion  22  may have any suitable size, shape, position or configuration to ensure engagement of the drive belt with the sprocket and proper contact between the scraper tip and belt when the belt is moving. 
     Referring to  FIGS. 3A-3C , in one embodiment, a self-biasing scraper  120  may include a counter weight  170  for increased tensioning of the scraper tip. The illustrative counter weight  170  comprises a central bar  171  and end discs  172 . The scraper  120  includes arms  173  extending from the base  122  substantially opposite the tapering scraper blade tip  130  for receiving the central bar  171 . As shown in  FIGS. 4A and 4B , the arms  173  include rounded tips  174  forming channels  175  for seating the counter weight central bar  171 . Arms  173  and the scraper blade tip  130  form a lever system pivoting about the shaft  118 , where the weight of the counter weight  170  is transmitted through the arms  173  and the tip  130  to the edge  132  to increase the pressure between the scraper edge  132  and the belt for improved scraping performance. The illustrative arms  173  take the shape of bars, but the invention is not so limited and arms  173  can be any shape and dimensions to take the advantage of a lever system. 
     The self-biasing scraper in  FIGS. 4A and 4B  also includes cut outs  135  in the scraper tip  130  to facilitate cleaning and—or to make the scraper tip  130  lighter. 
     In the illustrative embodiment, the scraper tip  130  and arms  173  are slightly less than 180° apart, but the invention is not limited to the illustrated orientation. 
     In another embodiment, shown in  FIG. 5 , a self-biasing scraper  220  with a tapering scraper tip  230  may include a single, solid arm  273  forming a continuous channel  275  for receiving a counter weight. 
     In another embodiment, shown in  FIGS. 6A and 6B , a self-biasing scraper  320  with a tapering scraper tip  330  may include an integral counter weight  370 . The counter weight  370  can be a solid plastic bar connected to the scraper base  322  by arms  373 . Alternatively, the counter weight  370  may have inserted rods made from materials such as stainless steel that are not visible from the outside. The illustrative counter weight  370  has the shape of a bar, though the invention is not so limited and the counter weight  370  can be any shapes and may be made from the same or different materials as the base  322 . In the illustrative embodiment, the scraper tip  330  and the counter weight  370  are slightly less than 180° apart, but the invention is not so limited. 
     Referring to  FIGS. 7A-8D , in another embodiment of the invention, a self-biasing scraper  420  may be designed to receive snap-on position limiters. The self-biasing scraper  420  is mounted on a longitudinal mounting bar  480  within the base portion  422 . The longitudinal mounting bar  480  has a longitudinal channel  481  on an outer surface and notches  482 . A tapering scraper tip  430  extends from the base portion  422 . The scraper  420  further includes arms  473  for holding a counter weight  470 , which may alternatively be integrally formed with the rest of the scraper. The scraper tip  430  includes openings  438  exposing the bar  480 . A plurality of snap-on position limiters  500  may be mounted to the scraper  420 . Examples of snap-on position limiters are described in U.S. Pat. No. 9,296,565, entitled “Snap-On Position Limiter for a Conveyor Belt”, the contents of which are herein incorporated by reference. The invention is not limited to those described position limiters and the self-biasing scraper may be designed to accommodate any suitable auxiliary component in a conveyor. The illustrative position limiters  500  comprise a limiting surface  520  facing the conveyor belt for ensuring proper engagement of the sprocket and conveyor belt. The base of the position limiter forms a snap clamp for engaging the bar  480 . Each position limiter  500  fits into an opening  438  to snap onto the mounting bar  480 . The illustrative mounting bar  480  includes a longitudinal channel  481  and notches  482  for engaging corresponding features on the position limiter snap clamp.  FIG. 8B  is a bottom view of the self-biasing scraper  420 , with the position limiters  500  snapped into place.  FIG. 8C  is a side view of the self-biasing scraper  420 , with position limiters  500  snapped into place. 
     The scraper  420  can rotate freely about the shaft  480  without interfering with the limiter  500 , as shown in  FIG. 8D . 
       FIGS. 9A and 9B  show another embodiment of a self-biasing scraper  620  including a tapering scraper tip  630  and an integral counter weight  670  extending from a base  622 . As shown in  FIGS. 9A and 9B , the base  622  can be an open segment of a tube that can receive a mounting bar via an opening  624  in the base  622 . The top of the base  622  contacts a moving conveyor belt at a first location to bias the tip  630  into contact with an outer surface of the conveyor belt at a second location. 
     Although the invention has been described in detail with reference to a few exemplary versions, other versions are possible. So, as these few examples suggest, the scope of the claims is not meant to be limited to the versions described in detail.