Abstract:
A reversible belt scraper blade provides two opposed scraping surfaces on an integrally constructed body. Each scraping surface has an elastomeric wear region transitioning to an elastomeric central region. Two integral frame members are integrally joined into the central region. Each integral frame member runs the length of the belt scraper blade and is at least partially exposed at their ends. End mounts attach to the exposed integral frame members and the reversible belt scraper blade is reversible about the end mounts. The wear regions may have sub-regions of different hardness to provide good scraping qualities combined with improved structural rigidity. The central region may also have sub-regions of different hardness to improve structural rigidity.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Application 61/180,783, filed on May 22, 2009, and the teachings in the specification and accompanying submissions for U.S. Provisional Application 61/180,783, are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to a belt scraper blade for a moving conveyor, more specifically this invention relates to a double edged belt scraper blade for endless conveyor belts carrying mining materials or earth, or other such materials. Belt scrapers are used in these applications to remove material adhering to the belt on the return run of the belt after the belt has dumped the bulk of material that it is carrying. 
     BACKGROUND OF THE INVENTION 
     Modern mining techniques make extensive use of endless belts to carry mined material from one location to another. For example, continuous belts may be used to carry mined material out of a mine and deposit it external to the mine. Endless belts may also be employed for carrying materials between processes. These belts can be extremely long and can move the material at high linear speeds. At the end of the belt, or rather where the belt begins its return journey, the belt passes around a wheel or pulley and begins the return journey. At that location, the materials on the belt are deposited. However, it is common for some residual material to adhere to the belt. 
     To reduce dust problems, particularly in coal mining, the load on the belt is sprayed with water. While this suppresses the dust, it increases the amount of material that adheres to the belt when the load is clumped. This material can transfer to pulleys, rollers, idlers, and bearings and build up. This build up of material causes excessive wear at a minimum and can cause seizing in bearings and may lead to fires, a catastrophic result. Belt scrapers are employed to remove this material from the belts to prevent the transfer to other elements of the conveying system, thereby preventing damage to those elements. 
     Scrapers are positioned to contact the belt on the terminating wheel or on the return run of the belt to remove this residual material. The dynamic nature of the environment and the abrasive nature of the materials being carried by the endless belt require belt scrapers that are durable and that can be maintained in contact with the belt with consistent pressure. The belt scrapers are expendable elements of the system and any economy that can be achieved with the belt scrapers is an improvement in the economic efficiency of the system. It is therefore highly desirable to have belt scrapers that are durable, that can be used over an extended period of time, and that can be economically manufactured. 
     RELEVANT ART 
     U.S. Pat. No. 5,628,392 by Stoll et al. claims a reversible belt scraper blade for cleaning high speed conveyor belts. A reversible belt scraper is provided with opposite belt scraping surfaces and is adapted to be reversed by inverting. The belt scraper is formed with a pair of metal side frames, and a transversely elongated body is formed as a block of rubber defining the belt scraping surfaces on opposite sides. A pair of fiberboard backing plates is positioned to support the rubber block against forces tending to bend or deflect the rubber. The fiberboard backing plates wear at a rate faster than the wear rate of the rubber block and assure full contact between the belt and the rubber scraping body. In a further embodiment, ceramic bricks are embedded within the rubber block with wear surfaces at the rubber scraping surface. The rubber, brick, and hacking plates are formed in modular segments which are stacked end-to-end between the frames and retained by metal slugs which extend through the segments. 
     Referring to  FIG. 1 , a prior art reversible belt scraper blade  10  may be seen. The prior art reversible belt scraper blade  10  of  FIG. 1  comprises a rubber body or block  12  with two face surfaces  14 , two phenolic resin impregnated fiber backing plates  16 , two transversely extending steel side frames  18 , two support ends  20 , and several steel rectangular segments or slugs  24 . The face surfaces  14  of rubber body or block  12  provide a cleaning region where belt scraper  10  contacts the belt and removes material from the belt, while phenolic resin impregnated fiber backing plates  16  provide strength and rigidity to rubber body or block  12  near the belt. Phenolic resin impregnated fiber backing plates  16  provide strength to rubber body or block  12  to maintain contact with the belt without risking damage to the belt which may result if metal reinforcements are used and come into contact with the belt. Although phenolic resin impregnated fiber backing plates  16  may be integrally molded onto rubber body or block  12 , transversely extending steel side frames  18  along with support ends  20  provide a framework to keep phenolic resin impregnated fiber backing plates  16  in contact with rubber body or block  12  while reversible scraping blade  10  is in use in the high demand environment. 
     Transversely extending steel side frames  18  are joined with end flanges  22  of support ends  20 . Support ends  20  have a cruciform cross section extending from reversible scraper blade  10  which is used to mount reversible scraper blade  10  in proximity to a belt. Several steel rectangular segments or slugs pass all the way through the body of reversible scraper blade  10  to pin transversely extending steel side frames  18  and phenolic resin impregnated fiber backing plates  16  to rubber body or block  12 . Phenolic resin impregnated fiber backing plates  16  may have slots cut in them to accommodate steel rectangular segments or slugs  24 , while rubber body or block  12  may simply have the steel rectangular segments or slugs punched through them. Transversely extending steel side frames  18 , support ends  20 , and steel rectangular segments or slugs  24  provide a framework to hold phenolic resin impregnated fiber backing plates  16  to rubber body or block  12  and gives reversible scraping blade  10  sufficient rigidity to maintain contact with a belt. 
       FIG. 2  is an end view of reversible scraping blade  10 . In  FIG. 2 , an embodiment is shown where face surfaces  14  are extended somewhat beyond phenolic resin impregnated fiber backing plates  16 . This is an initial state of reversible scraping blade  10 , and as reversible scraping blade  10  is used, face surfaces  14  will wear down to approximately flush with phenolic resin impregnated fiber backing plates  16  and both face surfaces  14  and phenolic resin impregnated fiber backing plates  16  will wear together. 
       FIG. 3  is a cross-sectional view of the prior art reversible belt scraping blade  10  of  FIG. 1  as indicated by arrows  3  in  FIG. 1 . In  FIG. 3 , steel rectangular segments or slugs  24  can be seen passing through transversely extending steel side frames  18 , phenolic resin impregnated fiber backing plates  16 , and rubber body or block  12 . Steel rectangular segments or slugs  24  supplement the rigidity of the framework provided by transversely extending steel side frames  18  and support ends  20 . 
     Further information and discussion of prior art reversible belt scraping blade  10  can be found in U.S. Pat. No. 5,628,392 by Stoll et al. However, the terminology and numbering may be different than that used herein. While the prior art reversible belt scraping blade  10  of U.S. Pat. No. 5,628,392 has excellent wear and rigidity along with the economy provided by the reversible nature of reversible belt scraping blade  10 , the manufacture of reversible belt scraping blade  10  is somewhat labor and process intensive and the composite nature of reversible belt scraping blade  10  can limit the forces that may be applied to reversible belt scraping blade  10 . 
     U.S. Pat. No. 4,696,388 by Stoll is for a conveyor belt scraper blade with contoured surface comprising a conveyor belt scraper blade assembly having an elongate blade body made of a resilient material and having a longitudinally-extending belt scraping surface, a frame attached to the body which imparts a convex shape to the belt scraping surface, and a pair of brackets mounted on the ends of the body for attaching the blade assembly to supporting structure. In a preferred embodiment, the blade body includes a central longitudinal slit and the frame includes an insert having a double convex shape which is fitted within the slit. The frame further includes a pair of opposing side walls which are attached to the insert and include a plurality of inwardly-directed prongs which engage the blade body and hold the body in position relative to the insert. 
     U.S. Pat. No. 6,619,469 by Malmberg is for a scraper blade made of more than one material. The scraper blade has at one end a scraper tip and at the other end a mounting base. The scraper tip is outwardly tapered. The scraper blade has at least two layers of different materials. The layer of material which is facing forward, i.e. that first meets the surface to be scraped, and which is adapted to form the actual scraper tip is made of a material which is both softer and more abrasion resistant than said other layer. 
     U.S. Pat. No. 7,007,794 by Waters et al., is for a one-piece integral multi-durometer scraper blade for a conveyor belt cleaner. The scraper blade includes a body extending longitudinally between a first end and a second end and extending transversely between a base and a tip. The body includes a first body portion comprising a first elastomeric material having a first durometer of hardness, and a second body portion comprising a second elastomeric material having a second durometer of hardness. The body also includes a transition portion located between the first body portion and the second body portion. 
     U.S. Pat. No. 7,461,736 by Waters et al, is a method patent generally claiming the methods of producing the apparatus claimed in U.S. Pat. No. 7,007,794. The methods claimed in U.S. Pat. No. 7,461,736 are directed to producing belt scraper blades that have various arrangements of materials of different durometers molded into a single unitary blade. 
     U.S. Pat. No. 4,202,437 by Gordon is for a scraper assembly for a conveyor belt. A conveyor belt scraper assembly having a scraper core attached to a shaft which holds the scraper core in adjustable spatial relationship with the conveyor belt, the scraper core having slide-in mounting channels which hold resilient scraper blades in contact with the conveyor belt to remove foreign matter therefrom and to allow expeditious replacement of worn-out blades, the scraper core also being rotationally and linearly adjustable to permit compensation for a substantial range of wear on the blade edge surface. 
     SUMMARY OF THE INVENTION 
     It is highly desirable to have a belt scraper blade that combines many features. It is desirable that a belt scraper blade be economical by providing multiple cleaning edges or surfaces allowing the belt scraper blade to be used multiple times. It is desirable that the cleaning edge or surface in contact with the belt be easily changed. It is desirable that the cleaning surfaces of the belt scraper blade be abrasion resistant. It is desirable that the belt scraper blade provide low risk of damage to the conveyor belt while minimizing the deformation and deterioration of the effectiveness of the cleaning surface. It is desirable that the overall structure of the belt scraper blade be sufficiently rigid to maintain contact with the belt. It is desirable that the belt scraper blade be easily produced. It is desirable that the easily produced belt scraper blade be of integral construction to enhance durability. The embodiments of the reversible belt scraper blade of the current invention meet these needs. 
     At least one embodiment of the double edged belt scraper blade has a body with two opposing contact surfaces having two wear regions extending from the contact surfaces to a central region. The central region of the body partially encases two integral frame members which run from end to end to the body. End mounts attach to the integral frame members at each end of the body. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art reversible belt scraper blade. 
         FIG. 2  is an end view of a prior art reversible belt scraper blade. 
         FIG. 3  is a sectional view through a prior art reversible belt scraper blade of  FIG. 1  taken along line  3 - 3  of  FIG. 1 . 
         FIG. 4  is a perspective view of an embodiment of the reversible belt scraper blade. 
         FIG. 5  is an end view of an embodiment of the reversible belt scraper blade without end mounts. 
         FIG. 6  is a perspective view of an embodiment of the reversible belt scraper blade without end mounts. 
         FIG. 7  is an end view of an embodiment of the reversible belt scraper blade with end mounts. 
         FIG. 8  is a side view of an embodiment of the reversible belt scraper blade with end mounts. 
         FIG. 9  is a side view of an embodiment of the reversible belt scraper blade without end mounts. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring now to  FIG. 4 , an embodiment of the reversible belt scraper blade  30  of the present invention is shown. Reversible belt scraper blade  30  is generally made of a body  40 , end mounts  50 , and integral frame members  60 . End mounts  50  and integral frame members  60  provide structure and a mounting framework to mount reversible belt scraper blade  30 , while contact surfaces  42  on body  40  actually contact the belt and scrape material from the belt. Body  40  may be made of one or more materials such as rubber, urethane, or other elastomer, and when body  40  is made of more than one elastomer, they may have different durometer values or hardness. Body  40  is integrally formed around integral frame members  60  with at least a portion of integral frame members  60  exposed at the surface, which provides a structure to which end mounts  50  attach. 
     Referring now to  FIG. 5 ,  FIG. 5  is an end view of reversible belt scraper blade  30  without end mounts  50 . It can be seen in  FIG. 5  that while body  40  extends continuously from contact surface  42  at one scraping surface to another contact surface  42  at a second scraping surface, body  40  also has regions subdividing it. Referring now to only the top portion of body  40  in  FIG. 5 , it can be seen that a large, substantially rectangular region defines most of the top portion of body  40  and this large, substantially rectangular region  44  is topped by contact surface  42 . Contact surface  42  has a leading edge  72  and a trailing edge  74 . To one side of large, substantially rectangular region  44  is a thinner contoured second region  46 . Together, first region  44  and second region  46  combine to form a wear region that will wear and be consumed as contact surface  42  scrapes on a belt to remove material. In the embodiment shown in  FIG. 5 , as belt scraper  30  wears, trailing edge  74  will move back to second region  46 . 
     Large, substantially rectangular first region  44  and thinner contoured second region  46  may be made of materials having different durometer readings. In embodiments made of more than one elastomer, knit line  48  in  FIG. 5  demarcates the differences in material of first region  44  and second region  46 . In most such embodiments of reversible belt scraper blade  30 , first region  44  will have a lower durometer reading and therefore be softer while second region  46  will have a higher durometer reading and therefore be harder, or stiffer. This configuration provides a large but soft contact surface  42  predominantly of region  44  which can remove material from a belt while remaining more abrasion resistant than second region  46 . Second region  46 , with its harder durometer reading, provides stiffness and structural support to first region  44  so that first region  44  can withstand greater contact pressures against the belt without excessive deformation away from the belt. Although knit line  48  is shown as a distinct line, it may, in many embodiments, actually represent a transition zone from a first durometer reading region to a second durometer reading region. Second region  46 , with its higher durometer reading, provides structural stiffness and support to first region  44  without the need for an additional metal stiffener or similar item to provide strength near to the belt. The direction of movement of the belt will usually be from the free corner of contact surface  42 , leading edge  72 , toward the corner of contact surface  42 , trailing edge  74 , supported by second region  46 . The wearing of second region  46  is designed to keep pace with the wearing of first region  44 . 
     Referring still to  FIG. 5 , the ends of integral frame members  60  can be seen. Integral frame members  60  run from end to end of reversible belt scraper blade  30 , as may be seen in  FIG. 4 , and integral frame members  60  are comprised of two legs, a surface leg  62  and a transverse leg  64 . Surface leg  62  forms part of the surface of reversible belt scraper blade  30  and provides strength to belt scraper blade  30  in the direction normal to edge surfaces  42 . Transverse legs  64  of integral frame members  60  extend into the interior of body  40  and provide strength to the reversible belt scraper blade  30  in the direction parallel to contact surfaces  42 , or in the direction of travel of the belt. Transverse leg  64  of integral frame member  60  also provides an anchoring contour for integral frame members  60  to thoroughly join or integrate with body  40  of reversible belt scraper blade  30 . 
     Body  40  has a central region  47  which is located between integral frame members  60 . In some embodiments of reversible belt scraper blade  30 , central region  47  may have the same durometer material as first rectangular region  44 . Other embodiments of reversible belt scraper blade  30  may have additional elements in central region  47 . Referring to the embodiment shown in  FIG. 5 , lines  68 , while representing the edges of the surface feature notch  49 , also indicate the boundary of an additional structural feature, web region  69 . Web region  69  spans the space between integral frame members  60  providing additional structural strength to that provided by integral frame members  60  by approximating the structure of an I-beam. In particular, web region  69  provides additional strength in the direction perpendicular to the belt width dimension of reversible belt scraper blade  30 . 
     In use, reversible belt scraper blade  30  is mounted by end mounts  50 , see  FIGS. 4 ,  7 , and  8 , and held in contact with a belt passing at relatively high rate to scrape residual material from the belt. Surface legs  62  of integral frame members  60  provide structural rigidity to maintain reversible belt scraper blade  30  in contact with the belt along the width of the belt. Transverse legs  64  of integral frame members  60  provide structural rigidity in the direction of travel of the belt. However, being mounted by its ends, reversible belt scraper blade  30  may experience forces at considerable distance from any point where it is supported. For example the middle of reversible belt scraper blade  30 , concurring essentially with the middle of the belt, may be a considerable distance from end mounts  50  where reversible belt scraper blade  30  is mounted and supported. Additionally, if reversible belt scraper blade  30  is used on the bottom side of a belt which is carrying a load, as opposed to being used on the load carrying surface on the return run, the load is likely to be heaviest in the middle of the belt and therefore the forces the greatest at the middle. Since the belt is traveling and not static, this results in substantial transverse loads on reversible belt scraper blade  30 . Web region  69  provides additional structural rigidity to reversible belt scraper blade  30 , particularly in the direction parallel to belt travel and transverse to belt width. 
     In some embodiments of reversible belt scraper blade  30  having web region  69 , web region  69  may be made of an elastomer of higher durometer than is present in the rest of central region  47 . The higher durometer elastomer has greater stiffness and therefore better provides strength. Although lines  68  in  FIG. 5  indicate a web region  69  with clearly defined boundaries and discontinuous transition from one durometer to another, web region  69  may vary in shape along the belt width dimension of reversible belt scraper blade  30  and the durometer for web region  69 , and the durometer for the rest of central region  47  may have a gradual change from one to the other through a transition zone. The shape of web region  69  and the transition from one durometer to another will be determined by the particular application in which a given embodiment of reversible belt scraper blade  30  is to be used and the manner in which it is produced. 
     In some embodiments of belt scraper  30  having web region  69 , web region  69  may be made of an additional prefabricated insert such as integral frame members  60 . In these embodiments, web region  69  will have more clearly defined boundaries within central region  47 . In some embodiments of reversible belt scraper blade  30 , a prefabricated web region  69  may be attached to integral frame members  60 . This attachment may occur in any applicable manner such as welding, riveting, adhesive bonding, etc. 
     If the particular use for a given embodiment of reversible belt scraper blade  30  requires it, web region  69  may have a shape that varies along the belt width dimension of reversible belt scraper blade  30 . For example, web region  69  may be largest at the middle of reversible belt scraper blade  30  to provide greatest rigidity at a point furthest from support for reversible belt scraper blade  30 . This may be accomplished in embodiments of reversible belt scraper blade  30  having a higher durometer web region  69  or a prefabricated web region  69 . 
       FIG. 6  is a perspective view of reversible belt scraper blade  30  without end mounts  50 . In  FIG. 6 , notches  66  are more visible in integral frame members  60 . Notches  66  in integral frame members  60  are alignment features for placing integral frame members  60  in the mold for producing the body of reversible belt scraper blade  30  and are also location features for the assembly of end mounts  50  onto the rest of reversible belt scraper blade  30 . Notches  49  in the ends of body  40  are a function of the manufacture of reversible belt scraper blade  30  and not inherently necessary for the function of reversible belt scraper blade  30 . Although notches  66  in integral frame members  60  are useful to the production of reversible belt scraper blade  30 , they should not be regarded as a required feature of embodiments of the present invention and other methods could be used to facilitate the molding and assembly of reversible belt scraper blade  30 . 
       FIG. 7  is an end view of reversible belt scraper blade  30  with end mounts  50 . End mounts  50  may also be seen in  FIG. 4 . Prominent features of end mounts  50  are cruciform stud  52  and flanges  54 . Flanges  54  of end mounts  50  are welded to integral frame members  60  to complete the assembly of reversible belt scraping blade  30 . Cruciform studs  52  of end mounts  50  provide a positive mount for reversible belt scraper blade  30 . Cruciform studs  52  provide a quick and easy orientation of reversible belt scraping blade  30  so that reversible belt scraping blade  30  is positively located in its holder. Reversible belt scraping blade  30  may be reoriented by 180 degrees by rotating reversible belt scraper blade  30  about the axis represented by cruciform studs  52  to present a new contact surface  42  to the belt. This is a much less cumbersome process than flipping the reversible belt scraping blade  30  about its long dimension. 
       FIG. 8  is a side view of an embodiment of the reversible belt scraping blade  30  with end mounts  50  in place. End mounts  50  attach to integral frame members  60  at least at flange  54 . Cruciform mounting studs  52  provide means for mounting reversible belt scraping blade  30  in position to contact a conveyor belt. Contoured second region  46  is visible at the top of  FIG. 8 , while rectangular first region  44  is visible at the bottom of  FIG. 8 . 
       FIG. 9  is a side view of an embodiment of the reversible belt scraper blade  30  without end mounts  50 . Notches  66  in integral frame members  60  are visible at each end of reversible belt scraping blade  30 . Rectangular first region  44  is visible at the top of  FIG. 9 , while contoured second region  46  is visible at the bottom of  FIG. 9 . 
     While specific embodiments of reversible belt scraping blade  30  have been discussed, these embodiments should not be taken as exhaustive of possible embodiments which would still be within the scopes and claims of this invention. For example, while integral frame members  60  in the embodiments discussed have an overall “J” shaped cross section, integral frame members  60  could take many forms. Likewise, end mounts  50  are shown with a specific configuration, but would not necessarily have to have a cruciform stud in every case. For example, a square stud, or even a flat elongated stud, may suffice depending on the holder. In some embodiments, end mounts  50  may consist only of flanges  54  wrapped around integral frame members  60  with no protruding studs at all. Similarly, the specific configuration of first durometer region  44  running the width of reversible belt scraping blade  30  may comprise more or less of the bulk of body  40 , and second durometer region  46  may also comprise more or less of body  40 . Factors which may influence the ratio of these areas are the relative costs of materials and the specific applications in which the reversible belt scraping blade  30  is to be used. The abstract is intended only as a brief overview of the specification and is not intended to define the invention claimed. The drawings are not exhaustive depictions of the numerous embodiments encompassed by the present invention.