Abstract:
Disclosed herein are embodiments of a vibrating screen ( 10 ) for separation of materials by size. The vibrating screen ( 10 ) may include a chassis ( 100 ) with side walls ( 102 ) and a plurality of support members ( 104 A,  104 B); a vibrator ( 126 ) that generates vibrations; at least one screen panel ( 120 A,  120 B) mounted to the chassis ( 100 ); where a screen mounting system is used that includes an upper surface that is angled relative to the adjacent screen panel ( 120 A,  120 B).

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a vibrating screen. In particular, although not exclusively, the invention relates to a vibrating screen for separation of materials such as ores in mining and mineral processing with a high clearance below the screening panels. 
       BACKGROUND TO THE INVENTION 
       [0002]    Vibrating screens are typically used in the mining and mineral processing industries to separate materials, such as coal, by size. A vibrating screen typically has a chassis with screen panels. The chassis is typically rigid with various support members to ensure structural integrity. The chassis is mounted on springs, or the like, and has vibrators which cause the chassis, and therefore the screen panels, to vibrate. The screen panels have apertures which allow smaller sized material to pass through. In use, the chassis vibrates and material is passed over the screen panels and smaller material is separated from larger material as it passes through the apertures in the screen panels. 
         [0003]    Typically the screen panels are releasably mounted to stringers which extend longitudinally along the vibrating screens. The stringers are mounted in crossbeam portions of the chassis which pass underneath the panels between two side walls. Some material that passes through the apertures impacts with the crossbeam portions. The collision can cause wear to the crossbeam reducing its structural integrity. 
         [0004]    Furthermore, material can get jammed between the crossbeams and the screen panels and smaller material may settle on the crossbeams which, over time, may accumulate. Both of these outcomes reduce the clearance between the screens and the crossbeams. The reduced clearance can limit the size of particles that can pass through the screens and studies have shown that they can cause significant blocking of the screens. This effectively renders a portion of the screen unusable and therefore reduces the efficiency of the screen. This leads to greater energy usage and/or the material not being separated effectively. Additionally, the screen panels may also need to be replaced prematurely due to the blockages. This in turn increases costs and down time, further reducing efficiency. 
         [0005]    It will be clearly understood that any reference herein to background material or information, or to a prior publication, does not constitute an admission that any material, information or publication forms part of the common general knowledge in the art, or is otherwise admissible prior art, whether in Australia or in any other country. 
       OBJECT OF THE INVENTION 
       [0006]    It is an object of the invention to overcome or at least alleviate one or more of the above problems and/or provide the consumer with a useful or commercial choice. 
         [0007]    Other objects of the present invention will become apparent from the following description. 
       DISCLOSURE OF THE INVENTION 
       [0008]    In one form, although it need not be the only or indeed the broadest form, the invention resides in a vibrating screen comprising: 
         [0009]    a chassis including two side walls with a plurality of support members therebetween and a screen mounting system; 
         [0010]    at least one vibrator that generates vibrations in the chassis; and 
         [0011]    at least one screen panel mounted to the screen mounting system of the chassis; 
         [0012]    wherein the screen mounting system includes at least one stringer mounted to an extension member that extends upwardly from the support members. 
         [0013]    The support member may have an upper surface that is angled relative to adjacent screens. The upper surface of the support member may be declined with respect to a material flow direction across the adjacent screens. The support member may comprise an upper portion and a lower portion separated by a web portion. The upper and lower portions may be in substantially parallel planes. The web portion is in a substantially perpendicular plane to the upper and lower portions. In a one embodiment, the support member is an ‘I’-beam with an off centre web portion between upper and lower portions. The I-beam may have one or more reinforcing ribs, extending in a plane that is perpendicular to planes of the upper, lower, and web portions. 
         [0014]    The upper surface may be an outer surface of the upper portion. The support member may be mounted such that the upper, lower, and web portions are all angled relative to a stringer mounted to an extension member that extends upwardly from the support member. The extension member may displace the stringer away from the support member to provide a high clearance between the screens and the support member. The extension member may have a base portion and an extension portion. The extension portion may be in a substantially perpendicular plane to the base portion. 
         [0015]    The base portion may engage with the upper portion of the support member and, in one embodiment, the extension portion may engage with at least one stringer. The base portion and/or the extension portion may include apertures. The apertures may be utilized to fasten the base portion to the support portion of the support member and the extension portion to the at least one stringer. In one embodiment, the extension portion has a plurality of apertures aligned along an axis that is angled relative to a plane of the base portion. Alternatively it will be appreciated that the extension member may be integral with the stringer and/or support member. 
         [0016]    At least a portion of the support member may have a wear resistant coating. The wear resistant coating may be applied to at least a portion of the upper surface and/or at least a portion of a surface of the web portion. The web portion may be angled relative to the screen panels such that a surface of the web portion is angled generally towards the screens and another parallel surface of the web portion is angled generally away from the screens. At least a portion of the surface of the web portion that is angled generally toward the screens may have the wear resistant coating. The wear resistant coating may be substantially rubber or ceramic. 
         [0017]    The vibrating screen may further comprise one or more struts located between adjacent extension members. The struts may include mounting portions separated by a strut portion. The mounting portions may be mounting plates which are mounted to the strut portion. The mounting plates may include apertures. At least one aperture of the mounting plate may correspond to at least one aperture of the extension member, which may be of the extension portion of the extension member. 
         [0018]    In another form, the invention resides in a vibrating screen comprising: 
         [0019]    a chassis including two side walls with a plurality of support members therebetween and a screen mounting system; 
         [0020]    at least one vibrator that generates vibrations in the chassis; and 
         [0021]    at least one screen panel mounted to the screen mounting system of the chassis; 
         [0022]    wherein an upper surface of at least a portion of the support members is angled relative to adjacent screen panels. 
         [0023]    The upper surface of at least a portion of the support members and the adjacent screen panels may define a tapered opening therebetween. Further features of the present invention will become apparent from the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein: 
           [0025]      FIG. 1  is a perspective view of a vibrating screen according to an embodiment of the invention; 
           [0026]      FIG. 2  is a cross sectional view of the vibrating screen illustrated in  FIG. 1 ; 
           [0027]      FIG. 3  is a close up view of a portion of  FIG. 2 ; 
           [0028]      FIG. 4  is a perspective cross sectional view of the vibrating screen illustrated in  FIG. 1 ; 
           [0029]      FIG. 5  is a perspective view of a support member according to an embodiment of the invention; 
           [0030]      FIG. 6  is a perspective view of an extension member according to an embodiment of the invention; and 
           [0031]      FIG. 7  is a perspective view of a strut according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]      FIGS. 1 to 4  illustrate a vibrating screen  10  having a chassis  100  with two opposed side walls  102 , support members in the form of upper crossbeams  104 A and lower crossbeams  104 B, with an upper and lower screen mounting system including a plurality of upper stringers  106 A and a plurality of lower stringers  106 B. The vibrating screen  10  has an upper deck comprising a plurality of upper screen panels  120 A mounted to the upper stringers  106 A, and a lower deck comprising a plurality of lower screen panels  120 B mounted to the lower stringers  106 B. 
         [0033]    The vibrating screen  10  has two lifting beams  110  which can be used to lift and manoeuvre the vibrating screen  10 , typically with a crane (not shown). A vibrator reinforcing beam  112  is mounted between the side walls  102  with vibrators in the form of exciters  126  mechanically linked to a drive assembly  130 . Affixed to an outer surface of each side wall  102  is a front spring mount  116  and a rear spring mount  118  with front springs  116 ′ and rear springs  118 ′, respectively. In use the springs  116 ′ and  118 ′ are mounted on stands (not shown). 
         [0034]    As illustrated in  FIG. 2 , the upper stringers  106 A and lower stringers  106 B are mounted to the cross beams  104 A and  104 B via extension members  122 . The extension members  122  are mounted to an upper surface of an upper portion  1040  of the cross beams  104 A and  104 B and are mounted to stringers  106 A and  106 B. The extension member  122  mounting to the stringer  106 A and  106 B is vertically offset from the mounting to the cross beams  104 A and  104 B. Furthermore, the extension members  122  are configured such that upper surface of the upper portion  1040  of the cross beams  104 A and  104 B are angled relative to the respective stringers  106 A and  106 B that the extension member  122  is mounted to. As the screen panels  120 A and  120 B are mounted directly to the stringers  106 A and  106 B, such that they are in parallel planes, this results in the upper surface of the upper portion  1040  of the cross beams  104 A and  104 B to also be angled relative to adjacent screen panels  120 A and  120 B. 
         [0035]      FIG. 3  illustrates a cross beam  104 A and an extension member  122  in greater detail. The cross beam  104 A has an upper portion  1040  and a lower portion  1042  separated by a web portion  1044 . The cross beam  104 A generally represents resembles an ‘I-beam’ with an off centre web portion  1044 . Selected surfaces of the cross beam  104 A have a wear resistant coating  1046  which is typically rubber or a rubber based compound. Notably, the exterior surfaces that generally face the screen panels  120 A, being surfaces which are more likely to be impacted from material passing through adjacent screen panels  120 A, have the wear resistance coating  1046  applied thereto. A wear plate  1048  is located between particularly high wear portions of the wear resistant coating  1046  and the cross beam  104 A to provide additional protection to the cross beam  104 A should the wear resistant coating  1046  be compromised. 
         [0036]      FIG. 4  illustrates an underside cross-sectional view of the vibrating screen  10 . The upper and lower cross beams  104 A and  104 B each have sets of extension members  122  extending upwardly therefrom to the stringers  106 A and  106 B. Located between adjacent extension portions  1222  of the extension members  122  are struts  150  that are mounted with the extension members  122  to the stringers  106 A and  106 B. 
         [0037]      FIG. 5  illustrates a crossbeam  104 , which could be an upper crossbeam  104 A or lower crossbeam  104 B, in isolation. The cross beam  104  has an upper portion  1040  and a lower portion  1042  separated by a web portion  1044 . The upper portion  1040 , lower portion  1042 , web portion  1044  extend the length of the crossbeam  104  between two end plates  1048  that are used to affix the cross beams to the side walls  102  of the vibrating screen  10  (as shown in  FIG. 4 ). Between the upper portion  1040  and lower portion  1042  in parallel planes that are substantially perpendicular to the planes of the upper portion  1040  and lower portion  1042  as well as the plane of the web portion  1044 , are reinforcing ribs  1050  that strengthen the crossbeam  104 . As shown in  FIG. 5 , the wear resistant coating  1046  is only applied to portions of the upper surface of the upper portion  1040 , with un-coated portions being sized to receive extension members  122 . 
         [0038]      FIG. 6  illustrates an extension member  122  having a base portion  1220  with extension portions  1222  extending substantially perpendicularly therefrom. Notably, the extension member  122  has three extension portions  1222 A,  1222 B, and  1222 C extending therefrom. Each extension portion  1222 A,  1222 B, and  1222 C are generally planar wedge shapes which are of constant thickness. 
         [0039]    The base portion  1220  has a plurality of apertures  1224  which are arranged to correspond with apertures in the upper portion  1040  of the crossbeams  104  for mounting thereto. The extension portions  1222  also have a plurality of apertures  1226  which are arranged to correspond with apertures in the stringers  106 A and  106 B. The extension portion apertures  1226  are aligned along an axis which is angled relative to the base portion  1220  (seen most clearly in  FIG. 3 ). 
         [0040]      FIG. 7  illustrates a strut  150  having two end mounts  1500  separated by a bar  1502 . Each end portion  1500  has a pair of apertures  1504  which correspond to a portion of the extension portion apertures  1226 . As illustrated in  FIG. 3 , the strut  150  is mounted to the extension portion  1222  of the extension member  122 . As illustrated in  FIG. 4 , each strut  150  is mounted between adjacent pairs of extension members  122  and corresponding stringers  106 A and  106 B. 
         [0041]    In use, the vibrating screen  10  of the present invention receives material to be separated, typically an ore, and the drive assembly  130  powers the exciters  126  to generate vibratory forces which are transferred to the chassis  100 . This in turn transfers the vibratory forces to the side walls  102 , the upper and lower crossbeams  104 A and  104 B, the stringers  106 A and  106 B and the screen panels mounted thereon  120 A and  120 B. The vibrating screen  10  is able to vibrate independently of the ground due to the springs  116 ′ and  118 ′ which are typically mounted on stands (not shown). As the screen panels  120 A and  120 B vibrate the material to be separated vibrates and traverses the screen panels  120 A and  120 B. The material is subsequently separated as smaller particles pass through apertures in the screen panels  120 A and  120 B and larger particles stay above the screen panels  120 A and  120 B. 
         [0042]    Advantageously the vibrating screen  10  provides a higher clearance between the screen panels  120 A and  120 B and the crossbeams  104 A and  104 B than previous screens. The increased clearance makes it more difficult for material to settle on the crossbeams  104 A and  104 B and block the screen panels  120 A and  120 B. The angle of the surfaces of the crossbeams  104 A and  104 B sends any material that lands on the crossbeams  104 A and  104 B downwards due to gravity. Furthermore, the angle of the crossbeams  104 A and  104 B relative to adjacent panels  120 A and  120 B provides a tapered opening that reduces the likelihood of material being trapped as under vibration the material is urged out of the tapered opening. 
         [0043]    These features all improve the reliability and efficiency of the vibrating screen  10  as the screen panels  120 A and  120 B are less prone to blockages and, therefore, screen material more efficiently with less downtime. Furthermore, screen panel replacement can be less frequent resulting in reduced operating costs. 
         [0044]    In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc. 
         [0045]    The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention. 
         [0046]    In the present specification and claims (if any), the word “comprising” and its derivatives including “comprises” and “comprise” include each of the stated integers but does not exclude the inclusion of one or more further integers unless the context of use indicates otherwise.