Abstract:
A removable scraper blade tip and reusable pocket for a conveyor belt cleaner comprises a scraper blade with leg portions adapted to be releasably received by receiving compartments in a pocket member that is permanently affixed to a support frame. The scraper blade tip is press fit into the pocket and secured with the use of a self-locking mounting pin. Removal of the scraper blade tip requires removal of the mounting pin and applying a force to the scraper blade tip to break the press fit. A new scraper blade tip may be inserted with the pocket and secured with the mounting pin.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. provisional application No. 60/730,464 filed on Oct. 26, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to conveyor belt cleaners for use in connection with conveyor belts used for handling bulk solid materials or unit handling, and more specifically to conveyor belt scraper blades incorporating a permanent pocket associated with the conveyor belt cleaner cross-shaft and using removable and replaceable scraper blade tips that securely insert within the pocket.  
         [0004]     2. Description of Related Art  
         [0005]     Conveyor belt cleaners are used to remove materials that cling to the return run of conveyor belts after the belt has discharged its cargo. The cargo can be units such as letters or cartons or bulk solid materials including sand or gravel. The bulk solid materials that do not discharge from the belt at the desired discharge location through the action of gravity or centrifugal force accumulates on components of the belt cleaner or the conveyor belt surface causing productivity, cleanliness or safety problems. Conveyor belt cleaners are designed to be used with conveyor belts of various widths and speeds including use on very side, fast moving belts such as the MARTIN® SHD™ Belt Cleaner. A typical wide, high speed conveyor belt is 2.8 m (110 in.) in width and travels at approximately 7.5 m/s (1500 ft/min).  
         [0006]     Referring to  FIG. 1 , prior art belt cleaners for side, fast moving belts  8  embody a unitary urethane scraper blade  10  with a metal insert or inserts cast into the base of the blade to facilitate attachment of the blade to the support frame  12 . The inserts  14 , shown in detail in  FIGS. 2-5 , are fabricated metal inserts comprising a horse-shoe shaped upper section  16  and a base portion  18 . The upper section  16  allow the urethane material to flow through as the blade  10  is being cast, creating a mechanical lock between the insert  14  and the blade  10 . The base portion  18  includes threaded apertures  20  located to align with apertures (not shown) in the support frame  12  ( FIG. 1 ) and configured to receive correspondingly threaded bolts  22  ( FIG. 1 ) for securing the scraper blade  10  to the support frame  12 . The number of inserts used correlates to the blade width. Several blades are mounted in line on the support frame to crate a single unitary blade. The blades must be precisely positioned to prevent gaps or misalignment in the blades which could trap foreign material or allow the material adhering to the belt to create a hydroplaning action between the scraper blades and the conveyor belt. For these reasons, the holes in the support frame and location of the inserts in the blades must be within a close tolerance of a few millimeters.  
         [0007]     There have been several attempts to design a blade with a replaceable tip and reusable base made from urethane or reinforced urethane. With smaller belt cleaner blades it is possible to design such a system; the Roxon™ is one system designed for smaller belt cleaners. However, the extreme conditions and high forces involved is super heavy duty installations have lead to failed attempts to use a urethane base and replaceable tip.  
         [0008]     The arrangement shown in  FIGS. 1-5  exhibits many drawbacks. First, the inserts in this design are not easily removed from the blade for purposes of recycling or reuse with a different scraper blade. Moreover, the inserts must be precisely placed into the mold while the blade is cast to maintain proper alignment with the bolt holes in the support frame. Additionally, the support frame is biased to adjust the position of the scraper blade to maintain engagement between the scraper blade and conveyor belt surface as the blade wears down. Accordingly, the distance the support frame is located from the conveyor belt is determined by the size and position of the insert location within the blade to prevent the metal of the insert from coming into contact with the belt surface in the event the blade wears down beyond its useful life.  
         [0009]     The present inventive scraper blade addresses these and other concerns associated with the prior art.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     A preferred embodiment of the conveyor belt cleaner system for cleaning a surface of conveyor belt comprises: a support frame comprising a top surface; a pocket extending from the top surface of the support frame, the pocket comprising a front and back wall and sidewalls defining a pocket space, the front and back walls each comprising a concentrically aligned mounting bore; a removable scraper blade tip comprising a scraping portion and a first mounting leg extending from the scraper blade tip and adapted to be received by the pocket and comprising a receptor extending between a front and back surface of the mounting leg, the scraper blade tip movable between a first position and second position where the receptor is substantially concentrically aligned with the front and back wall mounting bores to form a through hole configured to receive and capture a fastener adapted to be removeably inserted within the through hole when the scraper blade tip is in the second position.  
         [0011]     The conveyor belt cleaner system of further comprises a front flange extending from the support frame towards the front wall. The front flange comprises an access bore substantially concentrically aligned with the mounting bore in the front wall. In the conveyor belt cleaner system, the pocket extends from the top surface of the support frame at an angle with respect to the top surface and the pocket is comprised of metal.  
         [0012]     In another embodiment, a support frame for a conveyor belt cleaner for cleaning a surface of conveyor belt comprises: a top surface; and a pocket extending from the top surface. The pocket comprises a front and back wall and sidewalls of metal. The front and back walls each comprise a concentrically aligned mounting bore; a pocket space defined by the front and back wall and sidewalls with the pocket space configured to receive the base portion of a scraper blade tip, and wherein the scraper blade tip comprises a receptor that concentrically aligns with the mounting bore to form a through hole for receiving the fastener configured to releasably secure the scraper blade tip within the pocket space.  
         [0013]     Another embodiment of the invention comprises a method of assembling a conveyor belt cleaner for cleaning a surface of a conveyor belt comprising: (a) providing a support frame comprising: a top surface; (b) providing a pocket extending from the top surface of the support frame, the pocket comprising a front and back wall and sidewalls defining a pocket space; (c) boring concentrically aligned mounting bores in the front and back walls; (d) providing a removable scraper blade tip comprising a scraping portion and a first mounting leg extending from the scraper blade tip and adapted to be received by the pocket; (e) boring a receptor into the first mounting leg, the receptor extending from a front surface of the mounting leg to a back surface of the mounting leg; (f) inserting the mounting leg within the pocket space until the receptor is substantially concentrically aligned with the front and back wall mounting bores forming a through hole; and (g) providing a mounting pin adapted to be removably inserted within the through hole formed by the front and back wall bores to secure the scraper blade tip within the pocket. While a particular order of steps are stated in the foregoing examples of methods, other variations in steps or the order in which they are performed should be deemed as being within the scope of the invention.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0014]      FIG. 1  shows a side perspective view of a prior art conveyor belt scraper blade;  
         [0015]      FIG. 2  shows a bottom perspective view of a plurality of prior art conveyor belt scraper blades;  
         [0016]      FIG. 3  shows a side elevation view of a prior art conveyor belt scraper blade;  
         [0017]      FIG. 4  shows a front elevation view of a component of a prior art conveyor belt scraper blade;  
         [0018]      FIG. 5  shows a side elevation view of a component of a prior art conveyor belt scraper blade;  
         [0019]      FIG. 6  shows front and top perspective view of the pocket member of the inventive replaceable scraper blade tip and pocket;  
         [0020]      FIG. 7  shows side and front perspective view of the inventive replaceable scraper blade tip and pocket;  
         [0021]      FIG. 8  shows and elevation view of the scraper blade top of the present inventive replaceable scraper blade tip and pocket;  
         [0022]      FIG. 9  shows a bottom and side perspective view of the scraper blade tip of the present inventive replaceable scraper blade tip and pocket;  
         [0023]      FIG. 10  is a cross-sectional view of a portion the base member of the pin mounting arrangement;  
         [0024]      FIG. 11  is a perspective view of the self-locking pin of the pin mounting arrangement;  
         [0025]      FIG. 12  is a side elevational view of the self-locking pin; and  
         [0026]      FIG. 13  is side elevational view, which is partially broken away, of the pin mounting arrangement of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]      FIGS. 6-13  show an inventive replaceable scraper blade tip and pocket for a conveyor belt cleaner comprising a pocket  24  associated with a support frame  12  comprising a cross-shaft, and a urethane scraper blade tip  10  with a body portion  26  and mounting legs  28 ,  30  extending therefrom to secure the scraper blade  10  within the pocket  24 . The scraper blade tip  10  further comprises an upper, scraping portion  32  configured to engage the outer surface of the conveyor belt  8  ( FIG. 1 ). The support frame  12 , and in turn the scraper blade tip  10 , is biased towards the conveyor belt  8  ( FIG. 1 ) to maintain engagement of the scraping portion  32  against the conveyor belt  8  ( FIG. 1 ).  
         [0028]     Turning to  FIG. 6 , the pocket  24  and support frame  12  assembly is shown. The pocket  24  comprises two opposing sets of sidewalls  34 ,  36  that can be mounted to or integrally fabricated with the support frame  12  to form a pocket space  38 . The first set of sidewalls  34  comprises a front wall  40  and back wall  42  of the pocket  24 . The sidewalls join together and mount to the support frame with a draft angle of preferably 5 degrees. It is, however, contemplated that a draft angle between 1 deg. and 5 deg. is suitable for purposes of the present invention.  
         [0029]     Additionally, as is seen in  FIG. 7 , the pocket  24  is mounted on an angle, with respect to the top surface of the support frame  12 , towards the conveyor belt  8  ( FIG. 1 ). The angled mounting of the pocket  24  aids in properly biasing the scraper blade tip  10  into scraping engagement with the conveyor belt  8  ( FIG. 1 ). In  FIG. 7 , the mount angle is 60 deg. from horizontal. However, the mount angle is a function of the mounting geometry at the installation site and ranges from any position from horizontal, depending on the particular geometry and installation location.  
         [0030]     The pocket  24  can be made from a variety of materials such as hot rolled, steel, stainless steel, cast iron, aluminum, or a high strength reinforced plastic. When the pocket  24  is fabricated from metal, the rotation of the support frame  12  is limited to prevent the top edge of the front wall  40  from the contacting the conveyor belt surface as the scraper blade tip  10  wears down to prevent abrasion of or damage to the conveyor belt surface. This is accomplished by disposing a stop member (not shown) on the support frame  12 .  
         [0031]     In the present embodiment of the invention, the pocket space  38  is divided into a first and second receiving compartment  44 ,  46  by a transversely disposed divider  48 . The first and second receiving compartments  44 ,  46  are adapted to receive the first and second mounting legs  28 ,  30  of the scraper blade tip  10  ( FIG. 8 ). The pocket  24  and scraper blade tip  10  are designed with draft angles so the tip fits tightly into the pocket with a friction or press fit.  
         [0032]     The front and back walls  40 ,  42  also include mounting bores  47  ( FIG. 13 ),  48 A, B associated with each receiving compartment  44 ,  46 . As is seen in  FIG. 6 , a front flange  52  extends from the support frame  12  and abuts the front wall  40  of the pocket  24  towards the top edge of the front wall  40 . The front flange  52  includes access bores  54 A, B that are substantially concentric with the mounting bores  47  ( FIG. 13 ) in the front wall  40  for accessing the fasteners  110  ( FIG. 13 ), as will be discussed in detail.  
         [0033]     Turning to  FIGS. 8-10 , the scraper blade tip  10  comprises an upper portion  32  including the scraping edge, a body portion  26 , and the first and second mounting legs  28 ,  30  extending from the bottom of the body portion  26 . Each mounting leg  28 ,  30  comprises a front  56  and back  58  surface and a receptor  60 A, B extending there between with a central axis  51 . When the mounting legs  28 ,  30  are removably secured within the receiving compartments  44 ,  46  ( FIG. 6 ), the receptors  60 A, B align with and are concentric with the mounting bores  47  ( FIG. 13 )  48 A, B on the front  40  and back  42  walls of the pocket  24 , thereby forming coaxially aligned through holes  62 A, B ( FIG. 7 ), each for removably receiving a fastener  110  ( FIGS. 11 and 12 ) to releasably secure the scraper blade tip  10  within the pocket  24 .  
         [0034]     In a preferred embodiment of the present inventing, the fasteners  110  comprise self-locking, mounting pins  110  ( FIGS. 11 and 12 ). Each receptor  60 A, B includes a first generally cylindrical chamber  63  formed by a generally cylindrical sidewall  64 . The first cylindrical sidewall  64  extends inwardly into the mounting leg  28 ,  30  from a first side surface  65  and is located generally concentrically about the axis  51 . The receptor  60 A, B includes a second generally cylindrical chamber  66  formed by a second generally cylindrical sidewall  67  that extends generally concentrically about the axis  51 . The second cylindrical chamber  66  and the second cylindrical sidewall  67  are generally located midway between the first side surface  66  and the second side surface  68  of the scraper blade  10 . Each receptor  60 A, B includes a third generally cylindrical chamber  69  that is formed by a third generally cylindrical sidewall  70  which extends generally concentrically about the axis  51 . The third cylindrical chamber  69  and third cylindrical sidewall  70  extend inwardly into the mounting legs  28 ,  30  from the second side surface  68 . The first, second and third cylindrical chambers  63 ,  65  and  69  and the first, second and third cylindrical sidewalls  64 ,  67  and  70  each preferably have the same diameter.  
         [0035]     Each receptor  60 A, B includes a fourth generally cylindrical chamber  76  formed by a fourth generally cylindrical sidewall  78  that extends generally concentrically about the axis  51 . The fourth cylindrical chamber  76  and the fourth cylindrical sidewall  78  are located along the axis  51  generally midway between the first cylindrical chamber  63  and the second cylindrical chamber  65 . A generally conical transitional wall  80  extends from the first cylindrical sidewall  64  inwardly to the fourth cylindrical sidewall  78 . A generally conical transitional sidewall  82  extends outwardly from the fourth cylindrical sidewall  78  to the second cylindrical sidewall  67 . The transitional sidewalls  80  and  82  extend generally concentrically about the axis  51  and are preferably inclined at an angle of the approximately thirty degrees to the axis  51 .  
         [0036]     Each receptor  60 A, B also includes a fifth generally cylindrical chamber  90  formed by a fifth generally cylindrical sidewall  92  that extends concentrically about the axis  51 . The fifth cylindrical chamber  90  and the fifth cylindrical sidewall  92  are located approximately midway between the second cylindrical sidewall  67  and the third cylindrical sidewall  70 . A generally conical transitional sidewall  94  extends inwardly from the second cylindrical sidewall  67  to the fifth cylindrical sidewall  92 . A generally conical transitional sidewall  96  extends outwardly from the fifth cylindrical sidewall  92  to the third cylindrical sidewall  70 . The transitional sidewalls  94  and  96  extend generally concentrically about the axis  51  and are preferably inclined at an angle of approximately thirty degrees to the axis  51 . The diameter of the fifth cylindrical sidewall  92  is equal to the diameter of the fourth cylindrical sidewall  78 . The diameter of the fourth cylindrical sidewall  78  and the fifth cylindrical sidewall  92  is shorter than the diameter of the cylindrical sidewalls  64 ,  67  and  70  by a distance such as approximately 1.5 mm or one-sixteenth of an inch. Each receptor  60 A, B includes a first inwardly projecting annular rib  100  formed by the cylindrical sidewall  78  and the transitional walls  80  and  82 , and includes a second inwardly projecting annular rib  102  formed by the cylindrical sidewall  92  and the transitional walls  94  and  96 .  
         [0037]     The self-locking pins  110  ( FIGS. 11 and 12 ) are typically made from stainless steel and are similar to those disclosed and claimed in U.S. Pat. No. 6,457,575 to Swinderman and assigned to the assignee of this application. The disclosure of the U.S. Pat. No. 6,457,575 is incorporated by reference herein. Insertion of the pins prevents the scraper blade tip  10  from  15  being accidentally dislodged from the pocket  24  during use of conveyor belt cleaner.  
         [0038]     Each self-locking mounting pin  110  includes a shank  112  having a generally linear central axis  114  and a head  116 . The shank  112  extends along the axis  114  between a first end  118  and a second end  120 . The head  116  is attached to the first end  118  of the shank  112 . The shank  112  includes a first generally cylindrical portion  130  having a first generally cylindrical surface  132  at the first end  118  which extend generally concentrically about the axis  114 . The head  116  is attached to the first cylindrical portion  130 . The shank  112  also includes a second generally cylindrical portion  134  having a second generally cylindrical surface  136  that is located concentrically about the axis  114 . The shank  112  also includes a third generally cylindrical portion  138  having a third generally cylindrical surface  140  which is located generally concentrically about the axis  114 . The second cylindrical portion  134  is located approximately midway between, and is spaced apart from, the first cylindrical portion  130  and the third cylindrical portion  138 . The cylindrical portions  130 ,  134  and  138  and the cylindrical surfaces  132 ,  136  and  140  each have a uniform diameter approximately equal to or slightly smaller than the diameter of the cylindrical sidewalls  64 ,  67  and  70  of the receptor  60 A, B of the mounting legs  28 ,  30 .  
         [0039]     The shank  112  also includes a fourth generally cylindrical portion  146  having a fourth generally cylindrical surface  148  located generally concentrically about the axis  114  and located  10  approximately midway between and spaced apart from the first cylindrical portion  130  and the second cylindrical portion  134 . A generally conical transitional surface  150  extends inwardly from the first cylindrical surface  132  to the fourth cylindrical surface  148 . A generally conical transition surface  152  extends outwardly from the fourth cylindrical surface  148  to the second cylindrical surface  136 .  
         [0040]     The shank  112  also includes a fifth generally cylindrical portion  160  having a fifth generally cylindrical surface  162  which is located generally concentrically about the axis  114  and which is located approximately midway between and spaced apart from the second cylindrical portion  134  and the third cylindrical portion  138 . A generally conical transitional surface  164  extends inwardly from the second cylindrical surface  136  to the fifth cylindrical surface  162 . A generally conical transitional surface  166  extends outwardly from the fifth cylindrical surface  162  to the third cylindrical surface  140 . The transitional surfaces  150 ,  152 ,  164  and  166  are preferably inclined at an angle of approximately thirty degrees to the axis  114 . The first cylindrical surface  148  and the fifth cylindrical surface  162  have the same diameter which is smaller than the diameter of the surfaces  132 ,  136  and  140  by a distance such as approximately one-sixteenth of an inch.  
         [0041]     The shank  112  includes a truncated conical tip  170  having a conical surface  172 . A generally cylindrical bore  174  is illustrated which extends through the tip  170  generally perpendicular to the axis  114 . The shank  112  includes a first annular groove  180  that extends concentrically about the axis  114  and that is formed between the first cylindrical portion  130  and the second cylindrical portion  134  by the fourth cylindrical surface  148  and the transitional surfaces  150  and  152 . The shank  112  also includes a second annular groove  182  which extends generally concentrically about eh axis  114  and that is formed between the second cylindrical portion  134  and the third cylindrical portion  138  by the fifth cylindrical surface  162  and the transitional surfaces  164  and  166 . The first annular groove  180  is adapted to receive and interlock with the first annular rib  100  of the receptor  60 A, B in the mounting legs  28 ,  30 . The second annular groove  182  is adapted to receive and interlock with the second annular rib  102  of the receptor  60 A, B in base member  40 . The mounting bores  47 ,  48  in the front and back walls  40 ,  42  are preferably slightly larger in diameter than the diameter of the cylindrical surfaces  12 ,  136  and  140  of the pin  110 . If desired the cylindrical portions and the conical portions of the pin  110  and the receptors  60 A, B may be formed in a generally rectangular or other polygonal cross-sectional shape.  
         [0042]     The scraper blade tip  10  is formed from a resilient elastomeric material, such as a rubber or urethane, and is preferably polyurethane. The receptors  60 A, B are formed by molding a cavity within the blade that corresponds to the geometry of the fasteners  110 . One method of forming the receptors  60 A, B is by inserting a pin in the mold and allowing the urethane to flow around it and cure. The pin can be easily removed when the blade tip  10  is still hot from the molding process. Removal of the pin when the blade tip  10  is at room temperature is more difficult.  
         [0043]     Referring to  FIGS. 6, 7  and  13 , during operation, the scraper blade tip  10  is press fit into the pocket space  38 . The mounting legs  28 ,  30  are inserted within the receiving compartments  44 ,  46  until the receptors  60 A, B align with the mounting bores  47 ,  48 A, B on the front  40  and back  42  walls of the pocket  24  to form the through holes  62 . To firmly secure the scraper blade tip  10  within the pocket space  38 , self-locking mounting pins  110  are removably inserted within the through holes  62  as is shown in  FIG. 13 .  
         [0044]     Removal and replacement of the scraper blade tip  10  involves reversing these steps. First, the self-locking mounting pins  110  are driven out of the remaining tip  10  with a punch inserted through the access bores  54 A, B in the font flange  52  of the pocket  24 . The tip  10  is then pried from the pocket  24  by inserting a chisel or screw driver in the blade at the intersection of the two legs of the tip and the top edge of the pocket  24 . B driving the wedge into this space the scraper blade tip  10  is quickly released from its tapered locking fit within the pocket  24 . The scraper blade tip  10  is then easily removed, the receiving compartments  44 ,  46  are cleaned and a new scraper blade tip  10  is inserted into the pocket  24  and secured with the original pins.  
         [0045]     Of the many advantaged of the present inventive design, the present design reduces the amount of urethane used by 30% and eliminates the cast-in-place inserts of the prior art blade design which in turn reduces the replacement cost for the user. The present inventive design also reduces maintenance labor because the blade tips can be changed without unbolting the blades from the frame. Additionally, the replaceable scraper blade tips are 35% lighter than the prior art design.  
         [0046]     The present inventive design also address problems present in prior art designs that utilize pockets cast from urethane or urethane with metal reinforcements embedded within. The use of all metal pockets reduces the cost and increases the life of the pocket. One significant issue addressed over the urethane pickets in the prior art is the failure and deformation under load over time of the urethane pockets. The required amount of metal to adequately reinforce the urethane is not cost effective. Additionally, the use of metal pockets enables the pockets to be fabricated as an integral part of the support frame, eliminating the need to bolt the pockets onto the support frame.  
         [0047]     Other variations that would be contemplated by those skilled in the art are considered as being within the scope of the invention.