Patent Publication Number: US-2016228917-A1

Title: Screen panel locking system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Australian Patent Application No. 2015900407 filed on Feb. 10, 2015, which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates generally to apparatus for screening, separating or grading materials, and is principally for use in the mining industry. The present invention is particularly directed to arrangements for fixing screen panels to the support frame of a vibratory screening machine and to the screen panels themselves. The system and panels are applicable for screening, separating and grading ores and other materials, and it will be convenient to hereinafter describe the invention in relation to that use. It is to be appreciated, however, that the invention is not limited to such apparatus and use. 
     BACKGROUND OF INVENTION 
     A reference herein to prior art is not to be taken as an admission that the prior art was known or that it was part of the common general knowledge as at the priority date of any of the claims. 
     Screening apparatus of the type with which the invention is concerned is generally used for screening, grading, or separating materials such as ores and comprises an array of screen panels which are removably fixed to a frame to provide a continuous screen deck. The material to be screened is fed onto the deck at one end and the apparatus is vibrated so that the material moves over and through its screening surface. The vibration forces are significant. 
     The screen panels in a screen deck are usually subject to wear, due to the abrasiveness of the mining materials typically being screened, and thus the screens require periodical replacement. This presents a difficulty with the attachment of the panels to the deck frame, as the attachment must be secure and robust and easily made, but it should also be releasable in a manner that is quick and easy. Applicant has developed several different forms of screen panel attachments, examples of which can be found in Australian patent no. 2012201297 and Australian patent no. 2012208984. 
     In addition to the need for screen panels to be easily attachable and releasable to and from a screen deck frame, screen panels should also be firmly secured in place on the deck and the screen array should not present gaps for passage of screening product or media other than through the openings formed in the screens themselves. If gaps do exist, then incorrect grade screening product can pass through the deck, or the screening product can become embedded between components of the screening deck and can cause wear to the screen panels or the screen deck frame. This can result in the need to clean parts of the vibratory machine or replace parts, either of which results in downtime of the vibratory machine. 
     Screen decks are therefore formed with either the side edges of adjacent screen panels abutting, or with cover strips employed between adjacent screen panels to overlie any gaps between the adjacent side edges. A screen deck can thus usually be formed without any gaps being present. However, if there is any movement of the screen panels during operation of the vibratory machine, then gaps can result. One form of movement that can create gaps is movement of screen panels in the direction of travel of the screening product over the screening deck. This type of movement is more likely to occur in so-called multi-slope or “banana” screening decks, in which the lead or initial section of deck is inclined or curved to increase the speed of the screening product across the initial section of the screening deck. Such screening decks can also provide other benefits or effects such as to promote water shedding from the screening product. For at least these reasons, the use of multi-slope screening decks is preferred in many installations. However, in the inclined or curved section of the screening deck, the screening product moves at high speed and the forces associated with that movement tends to push the screen panels over which the screening product travels. If the screen panels move under that load, gaps between panels can arise. 
     The present invention seeks to provide an arrangement in which the screen panels at the edge of the screen deck are located or secured in position against movement of the kind described above. The present invention does not concern itself with movement of screen panels that are inboard of the edge of the screen deck although it will be appreciated that the elimination of movement of screen panels at the edge of the screen deck will assist to prevent movement of the screen panels inboard of the edge, because there will be no forces from the edge panels acting on the inboard panels tending to cause them to move. The elimination of movement is intended once the screen panels at the edge of the screen deck have been finally positioned or installed, such that in some forms of the invention, movement of the screen panels at the edge is allowed for installation purposes, but movement is prevented once the panels have been fully installed ready for operation of the vibratory machine. 
     SUMMARY OF INVENTION 
     According to the present invention there is provided a screening apparatus, including:
         a plurality of spaced apart, substantially parallel elongate beams,   a plurality of screen panels mounted to the beams to form a broad, generally planar screening surface,   a pair of elongate side walls on opposite sides of the screening apparatus, side edges of screen panels that form an edge of the screening surface (hereinafter “edge panels”) extending in close facing relationship to the side walls,   elongate side clamps mounted to the side walls and having a bottom edge for bearing against an upper surface of the side edges of the edge panels of the screening surface,   the side edges of the edge panels including locating gaps and the side clamps including projections, whereby the projections are received within the locating gaps to locate the edge panels relative to the side clamps against movement of the edge panels lengthwise of the side clamps.       

     A screening apparatus as above described advantageously prevents lifting movement of the side edges of the edge panels by the bearing engagement of the side clamp on the side edges, while the screening apparatus also secures the side edges of the edge panels against movement lengthwise of the side clamps by the engagement of the projections of the side clamps within the locating gaps of the edge panels. Thus the side edges of the edge panels are secured against movement that could otherwise result in the formation of gaps between adjacent screen panels. 
     A screening apparatus as above described can be employed with any suitable screening apparatus in which side edge location of the edge panels is required. One particular form of screening apparatus to which the present invention is applicable has been developed by the applicant and includes a plurality of spaced apart, substantially parallel elongate beams and a plurality of screen panels mounted to the beams to form a broad screening surface. Each of the panels has a generally square or rectangular shape defining a first pair of substantially parallel edges and a second pair of substantially parallel edges. The panels are mounted adjacent to each other so that facing side edges of adjacent panels are in close facing relationship, while each panel is mounted to a pair of beams to bridge between two adjacent beams. 
     The panels are mounted to the beams by elongate fixing members that extend in the longitudinal direction of the beams and that engage the first pair of side edges of the panels. The fixing members have a pair of upstanding, generally longitudinal rails that are generally parallel and that are spaced apart to define a longitudinal gap between them. The panels are mounted to the beams by cooperation between the first pair of side edges of each panel with a rail of a fixing member. The first pair of side edges of each panel includes a longitudinal overhang that overlies an upper end of a rail and the overhang enters the gap between the rails. Each of the rails of each fixing member and the overhang of each panel are interrupted to form gaps that are aligned and within which a locking member is disposed to locate the panel relative to the fixing rail against movement of the panel along the fixing rail. 
     In the above form of screening apparatus, the edges of adjacent panels that are spaced from or remote from the side walls of the screening apparatus are secured against movement by the use of the locking members. However, the edge panels adjacent the side walls of the screening apparatus are not connected to fixing rails and therefore, the use of locking members at those edges is not available. Thus, the present invention can be used to secure the side edges of the edge panels and with those side edges secured according to the invention, all of the screen panels of the screening apparatus can be fully secured against movement. This is highly advantageous. 
     A further advantage of the present invention is that the edge panels are not secured in place until the projections enter the locating gaps and the side clamp is also secured in place. In this respect, the side clamps can be left loose during the assembly of the screen panels to the screening apparatus until the screen panels have all been located, such as by the locking members of the screening apparatus discussed above. The side clamps can then be positioned for receipt of the projections within the locating gaps and once received, the side clamps can be clamped in place. This means that the edge panels can be shifted as required prior to securing them in place so that the edge panels can be properly positioned in the screening apparatus to eliminate gaps in the screen deck. This shifting movement is usually quite small. 
     Still further, removal of an edge panel is not obstructed by the receipt of the projections within the locating gaps, because once the other edges of the edge panels are freed from any locating devices, the edge panels can simply be pulled out from underneath the side clamps, releasing the projections from the locating gaps. This means that the edge panels are very easy to remove for replacement. 
     Screen panels for use in a screening apparatus according to the invention can have an identical shape. This has advantages in production and storage of panels (reducing the number of different panels needing to be stored), while installation is facilitated given that the single form of panel can be used across a complete screening deck. Where a screening apparatus employs locking members as discussed above, the gaps provided in the edges of the screen panels for receipt of the locking members can also form the locating gaps for receipt of the projections of the side clamps. The projections need simply to be positioned appropriately for alignment with the gaps and sized for receipt within the gaps. 
     The side clamp of a screening apparatus according to the present invention will extend longitudinally of the screening apparatus for substantially the extent or length of the screen panels and the side clamp will cooperate with a clamping arrangement which can for example engage an upper edge of the side clamp to push or press the side clamp downwards. 
     The projections preferably have a width between opposite side surfaces measured lengthwise of the side clamps that is substantially equal to the spacing between facing side surfaces of the locating gaps, so that the side surfaces of the projections engage the side surfaces of the locating gaps. In this way, engagement between the opposite side surfaces of the projections and the facing side surfaces of the locating gaps prevents relative movement between the side edges of the edge panels and the side clamps. 
     Also, the projections preferably have a depth or length laterally to the lengthwise direction of the side clamps that the projections extend into contact with the inboard end of the locating gaps. In this way, lateral movement of the edge panels toward the side clamps is restrained. Thus, the edge panels are restrained at their side edges against movement lengthwise of the side clamps as well as laterally to the side clamps. 
     In preferred forms of the invention, the projections do not extend into engagement with the inboard end of the locating gaps, but rather, extend toward the inboard end but terminate prior to engaging the inboard end. In these forms of the invention, the projections can include plugs to bridge between the projections and the inboard end, so that the ends of the plugs extend into contact or engagement with the inboard end of the locating gaps. This form of the invention is advantageous, in that the length of the plug can be selected on the basis of the gap to be filled between the projection and the inboard end of the locating gaps. Where that gap varies, the form and size of the projection can also vary. This means that the size of the projections does not need to be varied and thus a single form of side clamp with one size of projection can be employed in different forms and sizes of screening apparatus, rather than forming a variety of different side clamps with projections of different depth or length. 
     The use of plugs attached to projections is also advantageous to deal with inaccuracy in screening apparatus. For example, the side walls of the screening apparatus might not be completely straight from one end of the apparatus to the other, so that where a projection might engage the inboard end of a locating gap at one point of the screen deck, at a different point, the projection might be slightly spaced from the inboard end. In that case, movement of an edge panel might not be sufficiently restrained laterally to the lengthwise dimension of the side clamps, so that gaps between adjacent panels could arise. Accordingly, by the use of plugs, which can be varied in length or depth, variations in the distance or space between a projection and the inboard end of a locating gap can be accommodated by selecting different sized plugs. This means that in a screening deck according to the invention, different sized plugs can be employed along the length of the side walls. 
     The plugs are preferably releasably connectable to the projections, so that in the event that an inappropriately sized plug is initially connected to a projection, the plug can be removed and replaced with a plug of correct length or depth. The alternative is for the plugs to be permanently connected to the projections after the initial connection is made. 
     The plugs can be connected to the projections in any suitable manner, such as by a threaded connection, a bayonet connection, or a snap-fit connection. However, in one form of the invention developed by the applicant, each projection includes an opening and each plug includes a head, a neck and a base, wherein the neck is of a smaller diameter than both the head and the base. In this arrangement, the plugs are connected to the projections by the plug extending through the opening in the projections so that the head is positioned between the projection and the inboard end of the locating gap, the neck is positioned within the opening of the projection, and the base is positioned on the opposite side of the projection to the head. The head and the base can be arranged to be in engagement with opposite sides of the projection to firmly secure the plug to the projection. The neck can be a loose fit within the opening or a close fit, such as a friction fit. 
     In the above arrangement, the base of the plugs could be removed, so that the plugs can consist of a head and neck only and in this arrangement, the neck can be a friction fit within the opening of the projection to secure the plug to the projection. The neck alternatively could be a loose fit and the plug could be retained connected to the projection by connection or engagement of the head of the plug with the inboard end of the locating gap. 
     In the above arrangements incorporating a head, a neck and a base, the base must be able to be pushed through the opening of the projection and to expand on the opposite side of the projection once it is through the opening. Accordingly, at least the base, but preferably the entire plug, must be formed from a flexible, or resilient or distortable material so that the base can be collapsed and recover once it is through the opening. In some forms of the invention, the plugs are formed from polyurethane, although other materials could be employed. 
     Where plugs are employed, the plugs include a portion that bridges between the projection and the inboard end of the locating gaps to engage the inboard end. That bridging portion can also have a width between opposite side surfaces, measured lengthwise of the side clamps, that is substantially equal to the spacing between facing side surfaces of the locating gaps, so that like the projections, side surfaces of the plugs engage the side surfaces of the locating gaps. This is considered to potentially assist location of the side edges of the edge panels against movement lengthwise of the side clamps, particularly where the projections do not have a depth which is sufficient to enter a substantial portion of the locating gaps. 
     The bridging portion of the plugs can be generally square or rectangular, or alternatively, it can be generally circular. The portion can, of course, be any suitable shape, but the above identified forms are preferred. 
     The projections can extend from any appropriate part of the side clamps, but preferably they extend from the bottom edge of the side clamps. The side clamps can also have a rear surface in facing engagement with the side walls of the screening apparatus and an opposite, front surface. The bottom edge of the side clamps can extend between the front and rear surfaces and the projections that extend from the bottom edge can extend inboard of the rear surface so that where the plugs include a base, the base can be positioned between the rear side of the projections and the rear surface of the side clamps, so that the base of the plugs is in engagement with the side wall. That engagement between the base and the side wall supports the plug and thus the projection so that a pushing or bearing load imposed by the edge panels on the plugs is resisted by engagement between the base of the plugs and the side walls. 
     The edge panels, like the panels inboard of the edge panels, have a height between the upper surface of the side edges and the opposite lower surface. In the present invention, the projections, and if provided, the plugs, can have a height that is equal to the height between the upper and lower surfaces, or the height can be less than that height. In arrangements considered by the applicant to date, the projections and plugs can be less than half the height of the side edges, and for example can be approximately one third or one quarter of that height. In some arrangements according to the invention, the plugs extend from proximate the upper surface of the side edges of the edge panels and terminate prior to the opposite lower surface. In arrangements in which the projections extend from the bottom edge of the side clamps, the projections will extend from proximate the upper surface of the side edges of the edge panels and depending on the height of the projections, can extend to the opposite lower surface or to a position prior to that surface as described above. 
     Where the projections extend from the bottom edge of the side clamp, it is not necessary that the projections extend for the full thickness of the side clamps between the front and rear surfaces. In some forms of the invention, the projection is positioned inboard of the rear surface of the side clamp (as discussed above) as well as being inboard of the front surface. In this arrangement, the surface of the bottom edge that is forward of the projections (in the direction of the screen panels) can bear against the upper surface of the side edges of the edge panels when the side clamp is clamped into position. This means that despite the provision of the projections extending from the bottom edge of the side clamp, the side clamp can nevertheless continuously clamp against the upper surface of the side edges of the edge panels for the full length of the side clamp. 
     The width of the projections relative to the width of the side clamp between front and rear surfaces can be any suitable ratio, and is dependent on the dimensions of the locating gaps provided in the side edges of the edge panels. What is required is that the projections are positioned and dimensioned sufficient to extend into the locating gaps to provide the longitudinal location required. As indicated above, the connection of plugs to the projections can extend the width or depth of the projections, for greater penetration into the locating gaps, but the preference is that the projections always extend into the locating gaps to at least some extent. 
     While any number of locating gaps can be provided on the side edges of the edge panels, two locating gaps appear to be appropriate, and the preference is that these are spaced apart towards opposite sides of the edge panels. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In order that the invention may be more fully understood, some embodiments will now be described with reference to the figures in which: 
         FIG. 1  is an isometric view of a portion of a screening deck according to one embodiment of the invention. 
         FIG. 2  is a cross sectional view through II-II of  FIG. 1  showing the connection between adjacent screening panels in the deck illustrated in  FIG. 1 . 
         FIG. 3  is an exploded view of a single screening panel and its connection to the deck of  FIG. 1 . 
         FIG. 4  is an assembled view of the arrangement of  FIG. 3 . 
         FIG. 5  is an exploded view of a single screening panel and its connection to the deck of  FIG. 1  but showing an elongate fixing member. 
         FIG. 6  is an isometric view of a locking member for use in a screening apparatus. 
         FIG. 7  is a cross sectional view through VII-VII of  FIG. 1  showing the locking member of  FIG. 6  in place. 
         FIGS. 8 and 9  show alternative forms of locking members. 
         FIG. 10  is an isometric view of a side clamp according to one embodiment of the invention. 
         FIG. 11  is an end view taken in the direction A of  FIG. 1 . 
         FIG. 12  is a cross sectional view through XII-XII of  FIG. 1 . 
         FIG. 13  is a cross sectional view of a plug according to an embodiment of the invention. 
         FIG. 14  is an isometric view of a side clamp according to one embodiment of the invention. 
         FIG. 15  is a cross sectional view of a plug according to a further embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1 , a portion of a screening deck  10  is illustrated, comprising a plurality of elongate, longitudinal beams  11  each of which is formed from an angle of steel having a long portion  12  and short portion  13 . The portions  12  and  13  are set at right angles to each other. While the beams  11  extend in the longitudinal direction of the screening deck  10 , the beams  11  can equally extend perpendicular to the direction shown. 
     The deck  10  illustrated in  FIG. 1  is a portion of a deck only and illustrates a depth across the deck  10  of four screening panels  15 . The longitudinal length of the deck  10 , in the direction of the beams  11  can be much greater. 
     The beams  11  extend parallel to one another and support the panels  15  on the upper face of the short portion  13  of each beam  11 . The panels  15  illustrated in  FIG. 1  can be of any suitable size, but a common size is 305 mm by 610 mm. The screening deck  10  is one part of an overall screening apparatus. The screen deck  10  is supported on a sub frame which includes the beams  11  and which is part of a vibratory screen machine. The vibration that is generated is significant and requires the panels  15  to be securely fixed to the beams  11 . The panels  15  are also subject to wear over time and even though the fixing of the panels  15  to the beam  11  are required to be secured, the preference is that the panels are also easily releasable to facilitate replacement. 
     The panels  15  include a plurality of openings through the top surface thereof for screening product such as mining ore. The openings in the panel can vary from large to very small depending on the screened media required from the screening process. 
     Typically, ore is fed onto one end of the deck  10  and the deck is vibrated so that the ore tends to shift from one end to the other with some of the ore passing through the openings of the panels  15  as it travels over the deck. Depending on the operation, the valuable ore could be the ore which passes through the openings, or the ore which remains on the deck. The panels  15  are attached to the screen deck  10  via elongate fixing members  20  which are mostly obscured in  FIG. 1 , but which are shown in other figures. The fixing members  20  are fixed to the upper surface of the short portion  13  of the beams  11  by any suitable arrangement, such as bolts. The fixing members can extend for a single length of a single panel  15 , or, more preferably, for a greater number of panels, such as five panels. 
     Most of the panels  15  will be in face to face engagement along side edges of each panel. For example, the panel marked P 1  is engaged with facing edges of other panels  15  on all four edges. It is preferred that the panels have this face to face engagement, in order to prevent or minimise screening product from entering into the junction between adjacent panels  15  and through that junction to the beams  11  below or into the screened product that is collected below the screen deck. Any entry of such screening product between adjacent panels  15  can cause wear to the fixing members  20 , or to the beams  11 , thus compromising operation of the screening deck  10 . With sufficient wear, worn components must be replaced and that results in down time of the screening apparatus. Wear of certain components, such as the beams  11 , can require significant down time in order to replace the components. It is therefore important that the panels  15  be fixed to the deck  10  securely and with firm side edge engagement between adjacent panels. 
     It is to be noted that the deck  10  includes side clamps  21  at each side of the deck  10 , and in facing engagement with side walls  22 . Side clamps  21  clamp via a bracket  23  and wedge  24  onto the upper edge surface of the panels  15  for the purpose of preventing lifting of the facing edge of the panels  15 , preventing ingress of screening product between the side edges of the panels  15  and the walls  22 , and also to protect the walls  22  (which are usually steel walls), from the impact of screening product which traverses the screen deck  10 . The side clamps  21 , like the panels  15 , are usually made from a polyurethane material. The side clamps  21  can be used with a screening apparatus of the invention or with prior art screening apparatus. 
     The manner in which the screen panels  15  interact with the fixing members  20  will be described hereinafter. For that discussion, it is important to note from  FIG. 1 , the existence of locking members  25  that assist to locate the panels  15  relative to the fixing rails  20  against movement of the panels  15  along the fixing rails. In this respect, while the deck  10  is shown as a flat, screening decks generally operate on an incline to promote travel of ore from one end of the deck (the feed end) to the other (the discharge end), and some decks incorporate inclined sections (these can be referred to as “multi-slope decks”), in order to increase the speed of ore from the feed end to the discharge end. The inclined sections can have a greater inclination at the start of the deck and reduce towards only a slight inclination so that screening product decelerates from a high speed at the entry or initial section of the screening deck, to a lower speed when the screening deck flattens out to a slight incline. These types of decks process the screening product more quickly than decks that have only a slight and constant incline over the length of the deck because the screening product travels over the deck more quickly due to the more greatly inclined sections. 
     Particularly in the multi-slope types of decks, there is tendency for the screening panels to shift in the direction of screening product movement due to the loads placed on the panels by the moving screening product and that shift can cause gaps to open between adjacent panels and for screening product to fall through those gaps causing the problems mentioned above in relation to wear of deck components or contamination of screened product. For this reason, the screening apparatus disclosed herein is intended to lock the panels  15  firmly in position on the fixing members  20  in order to prevent such panel shifting movement. That locking however is intended to be selective in that the screening apparatus can allow movement of the panels  15  relative to the fixing members  20  to allow proper and accurate location of the panels  15  on the fixing members  20 , but once the panels  15  are correctly located, the panels can be locked against further movement relative to the fixing members  20 . This differs from some prior art arrangements where the screening panels are locked as soon as they are fixed to the fixing members, so that initial pre-fixing movement along or relative to the fixing members is not provided or allowed. 
     With reference to  FIG. 2 , a cross-sectional view of one full panel  15  (the central panel), and side edges of two adjacent panels  15  (to the left and right of the central panel) is illustrated.  FIGS. 3 and 4  are exploded and assembled views of a single panel  15  relative to a single fixing member  20 .  FIGS. 2 to 4  show the configuration of the fixing members  20  and show that the fixing members  20  include a pair of rails  26  which extend from a base  27  and which are formed by webs  28  and heads  29 . Recesses  30  are defined between the base  27  and the heads  29  and it can be seen that the side edges of the panels  15  each include a projection  31  that extends into the recesses  30  in order for the side edges of the panels  15  to cooperate with the rails  26  of the fixing members  20  to fix the panels  15  to the fixing members  20  and thus to the beams  11 . 
     The side edges of the panels  15  also include a longitudinal overhang  34  ( FIG. 2 ) that overlies the upper end of the rails  26 , or in other words overlies the heads  29  and includes a downwardly extending portion  35  that extends into the gap G ( FIG. 2 ) between adjacent rails  26 . It is intended that facing surfaces of facing portions  35  engage tightly to prevent ingress of screening product between the portions  35  and into the fixing members  20 . 
     The panels  15  are securely located on the beams  11  by cooperation between the projection  31  of the side edges of the panels  15  within the recess  30  of the fixing members  20 . The panels  15  can be connected to the fixing members  20  by the projections  31  riding down the inclined surface  36  of the heads  29  and by the rails  26  bending inwardly towards each other as the projection  31  moves over the inclined surface  36  for insertion into the recess  30 . With the projection  31  seated within the recess  30 , the portion  35  is positioned within the gap G, and when a pair of panels have been assembled to the fixing member  20  as shown in  FIG. 2 , the respective portions  35  engage and prevent inward flexing or tipping of the rails  26  towards each other. By this arrangement, side edges of the panels  15  are securely held in place on the fixing members  20  by the secure engagement of the projections  31  within the recesses  30 . 
     However, as indicated above, it is a feature of the screening apparatus that the panels  15  are not only secured in the array formation shown in  FIG. 1 , but also against movement along the fixing members  20 . In the illustrated form of the screening apparatus, prevention of that latter form of movement is by the use of locking members  40  that fit into locating gaps which are formed in the overhang  34  and in the rails  26 . With reference to  FIG. 3 , gaps  41  are formed in the overhang  34 , while gaps  42  are formed in the rails  26  of the fixing member  20 . The gaps  41  and  42  form a locating gap into which the locking member can be inserted. 
     With reference to  FIG. 4 , with the gaps  41  and  42  aligned or overlaid, the locking members  40  can be inserted and it will be appreciated that once inserted, the locking members  40  lock the position of the panel  15  on the fixing member  20  through engagement with the edges of the gaps  41  and  42 . While the locking members  40  remain in place, movement lengthwise of the panel  15  along the fixing member  20  is not possible. 
     The figures mentioned above also show the manner by which the fixing members are fixed to the beam  11  and while this is a relatively standard arrangement, it will be briefly described as follows. 
     Extending from the base  27  of the fixing member  20  are a pair of projections  45  ( FIG. 3 ) that extend through openings  46  in the portion  13  of the beams  11  and while the projections  45  are not shown as being threaded, they include a thread over which the washers  47  pass and on which the nuts  48  thread. The nuts  48  tighten the fixing members  20  onto the beam  11 , while a urethane cap  49  is also threaded onto the end of the  45  to protect the fixing arrangement (the projections  45 , washers  47  and the nuts  48 ) against the corrosive effect of fines (very fine screening product). 
     The fixing members  20  can be of any length suitable to secure one or more panels  15 .  FIG. 5  illustrates a fixing member  50  that is of a length suitable to fix four panels  15  thereto. It is envisaged that for commercial use, the fixing members  20  will have at least the length shown in  FIG. 5  but potentially a greater length, although a smaller length is possible. 
     The locking members  40  must firmly lock into the gaps  41  and  42  and must be constructed to maintain that locking engagement under operation of the deck  10  during a screening operation in which the deck is vibrated. Accordingly, the locking members  40  include a construction that is illustrated in  FIGS. 6 and 7  and with reference to those figures, it can be seen that the locking member  40  has a generally rectangular shape and includes four projections or undercuts  52 . Each undercut  52  projects from a side wall or edge of the locking member  40  and includes an upper surface  53 . As shown in  FIG. 7 , two of the undercuts  52  on opposite sides of the locking members  40  engage a downwardly facing surface  54  of the inner edges or walls of the gaps  41  in adjacent panels  15  in order to lock the locking members  40  in place. The other two the undercuts  52  engage a downwardly facing surface of the other walls (the side walls) of the gaps  41  as will be below. The locking members  40  are intended to be a tight fit within the locating gaps formed by the overlying gaps  41  and  42 . 
     There is sufficient flexibility in the undercuts  52  in order to simply push the locking members  40  into the gaps  41  of an adjacent pair of panels  15  with the undercuts  52  compressing or deflecting to allow the locking members  40  to enter the gaps  41  and for the undercuts  52  to thereafter splay or flex outwardly once the upper surface  53  has penetrated to a position just below the downwardly facing surfaces  54 . As shown in  FIG. 7 , the bottom face  55  of each locking member  40  rests on upwardly facing surfaces  56  (see  FIGS. 3 and 4 ), of the rails  26  in the region of the gaps  42 . By this arrangement, each of the panels  15  and the locking member  40  are firmly secured in place and because the locking member  40  is a tight fit within the gap  42 , so that it bears against facing surfaces  57  (see  FIG. 3 ) of the heads  29  of the rails  26 , longitudinal movement of the locking members  40  is precluded and thus longitudinal movement of the panels  15  is also precluded. 
     While the undercuts  52  engage the surfaces  54  of the inner walls of the panels  15  as shown in  FIG. 7 , the undercuts  52  also engage further downwardly facing surfaces  58  of the side walls that extend from the inner walls as shown in  FIG. 3 , so that the locking member  40  is secured against release out of the gaps  41  and  42  on each of its four sides. This forms a highly secure fitting. 
     Locking members  25  and  40  are illustrated in  FIG. 1 , and from this, it can be seen that the locking members  25  have different shapes on the surface of the deck  10  to the locking members  40 . The form of the locking members can vary and two other forms are illustrated in more detail in  FIGS. 8 and 9 . Each of the locking members  40 ,  60  and  65  have the same bottom or base end defining a rectangular shape with four undercuts  52 . It is only the upper part of the locking members that differ and in  FIG. 8 , the locking member  60  is shown to have a diamond shaped upper end  61 , while in  FIG. 9 , the locking member  65  has a pyramid shaped upper end  66 . The upper ends  61  and  66  are shaped as deflectors, so that screening product travelling along the deck  10 , that travels along the adjoining sections of adjacent panels  15  in which no screening openings exist, is deflected back onto portions of the screening panels that do have screening openings. 
     Returning to  FIG. 1 , it will be evident that the arrangement which exists between adjacent side edges of adjacent panels  15  cannot be employed along the walls  22  of the deck  10  because there is no adjacent panel for the side edge panels to engage or abut. Nevertheless, is it important to secure the panels at the edges (referred to earlier as “edge panels”) against longitudinal movement of the deck  10  at the side walls  22 , so that the edge panels  15  that extend to the side walls  22  are also fully located against longitudinal movement. Also, it is important to secure the edge panels  15  against lateral movement toward and away from the side walls and against lifting movement away from the beams  11  of the screen deck. 
     For this, the side clamps  21  have been configured so that they can support plugs or spacers (hereinafter “plugs”) for interaction with the side edges of the edge panels  15 . With reference to  FIGS. 10 to 13 , the side clamp  21  includes a rear face  70 , a front face  71 , an upper stepped edge  72  which is engaged by the wedge  24  for securing the side clamp  21  in place, and a lower or bottom edge  73 . Extending from the lower edge  73  are projections  74  that each include an opening  75  for receipt of a plug  76 , which is shown in side cross sectional view in  FIG. 13 . 
     From  FIG. 13 , it can be seen that the plug  76  has a head  77 , a neck  78  and a base  79 . The dimensions of the openings  75  are such to snuggly or closely accept the neck  78 , and the arrangement is that the base  79  is sufficiently flexible to allow it to be pushed through the smaller diameter opening  75  and to splay or recover once through the opening  75  to engage against the rear surface  80  of the projections  74 , with the surface  80  being slightly inboard of the rear face  70  of the side clamp  21  so that the rear of the base  79  is coextensive with the rear face  70 . This means that the base  79  will engage against the side wall  22  and be supported by the side wall  22 . The distance D 1  between the bottom surface of the head  77  and the facing surface of the base  79  is also configured to be approximately the same as the distance D 2  between front and rear surfaces of the projections  74 . 
     With reference to  FIGS. 3 and 4 , and assuming for the purposes of the description in relation to the plugs  76 , that the side edge  82  of the panel  15  of  FIGS. 3 and 4  is the side edge  82  shown in  FIGS. 11 and 12 , then it will be apparent that the side edge  82  includes openings or gaps  41  (see  FIGS. 3 and 4 ) that are proximate the facing surface of the wall  22 . The projections  74  of the side clamp  21  shown in  FIG. 10  are therefore spaced apart for alignment with the gaps  41  in the side edge  82 . The projections  74  of the side clamp  21  also have a width dimension W 1  (see  FIG. 10 ) that is the same, or just slightly smaller than the width dimension W 2  of the gaps  41  (see  FIG. 4 ). When the projections  74  are located within the gaps  41 , side edges of the projections  74  bear against facing surfaces of the gaps  41  to locate the side edge  82  against longitudinal movement in the direction A (see  FIG. 1 ) between the feed and discharge ends of the screen deck  10 . By this arrangement, the side edge  82  is secured against that longitudinal movement to the same extent that that movement is secured at the opposite ends of the panels  15  by the earlier described locking members  25 ,  40 ,  60  or  65 . 
     The engagement should be enough to prevent longitudinal movement of the panels  15  in the direction A of  FIG. 1 . The fit of the projections  74  preferably should therefore be an interference type fit within the gaps  41 . The bearing engagement can be firm engagement and the dimensions of the projections  74  and the gaps  41  can be made so that the panels must be forced into position on the projections  74 , However, such a tight engagement is not considered to be absolutely necessary, so that a friction fit could be acceptable or even a slightly loose fit. 
     For the panels  15  to be secured against lateral movement toward and away from the side walls  22  (movement in the direction B as shown in  FIGS. 3 and 4 ), contact must be made with the inside, inboard or base surfaces  43  of the gaps  41 , It is not intended that the projections  74  will engage the base surfaces  43 , although in some arrangements this could occur, but rather, it is the intention that the plugs  76  engage the base surfaces  43 , The plugs  76  can be made in different lengths or sizes as explained below, to accommodate variations in the spacing between the base surfaces  43  and the facing surface of the projections  74  of different screening decks or machines, 
     The plugs  76  are proposed to be separate from the projections  74 , so that different sized plugs can be used to accommodate different spacing between the base surfaces  43  and the facing surface of the projections  74  as necessary. Thus, in relation to  FIG. 14 , the side clamp  21  is again shown, having the same features and thus the same reference numerals as the side clamp  21  as shown in  FIG. 10 . However, in  FIGS. 14 and 15 , plugs  84  are illustrated and those plugs have a different and reduced depth D 4  compared to the depth D 3  of the plug  76  of  FIG. 13 . The plug  84  has a head  85 , a neck  86  and a base  87 . The dimensions of both the neck  86  and the base  87  can be the same as the neck  78  and the base  79  of the plug  76 . Where the dimension differs in the respective plugs  76  and  84  is in the dimension or depth of respective heads  77  and  85 . As can be seen in  FIGS. 13 and 15 , the head  77  is of greater dimension or depth compared to the head  85 . 
     The dimensions of the plug  84  is for snug or close receipt of the neck  86  within the openings  75 , with the base  87  being sufficiently flexible to allow it to be pushed through the smaller diameter opening  75  and to splay or recover once through the opening  75  to engage against the rear surface  80  of the projections  74  in the same manner as the plugs  76  of  FIGS. 10 and 13 . 
     The different sizes or depth of the plugs  76  and  84  illustrated in  FIGS. 10 and 14  allows compensation for slight variations in the total width of the screening deck  10  between the opposite side walls  22  (see  FIG. 1 ) of different machines, or for inaccuracy of the side walls along the length of the screen deck from feed end to discharge end. This is important, because while the distance between the side walls  22  is specified for each screening deck, there can be slight variation along the length of the deck between the side walls (such as by slight bowing of the sides walls along their length), so that the size of the plug needed to engage the base surface  43  of the screen panels  15  can also vary. Moreover, different screen deck manufacturers manufacture their screen decks to different widths and where the variation between the width of the screen decks of different manufacturers varies by a few millimetres (say up to 30 mm), the same side clamp can be used for each deck with the plugs being selected based on the distance that the plugs need to bridge in order to ensure edge engagement between adjacent screen panels. 
     It is necessary for the plugs  76  and  84  to engage the inboard or base surface  43  of the gaps or openings  41 . The engagement should be enough to prevent lateral movement of the panels  15  in the direction B of  FIGS. 3 and 4 . The fit of the plugs  76  and  84  should preferably be an interference type fit so that the faces  89  of the plugs  76  and  84  bear against the base surfaces  43  of the gaps  41 . The bearing engagement can be firm engagement. The heads  77  and  85  can be made so that the panels must be forced into position against the plugs  76  and  84 , although such a tight engagement is not considered to be absolutely necessary. What is necessary is that the heads  77  and  85  of the plugs  76  and  84  take up the gap between the projections  74  and the facing base surfaces  43  and bear against the base surfaces  43 . 
     The plugs  76  and  84  can have the same width dimension W 1  (see  FIG. 10 ) as the projections  74 , so that the plugs  76  and  84  can also engage facing surfaces of the gaps  41  in the same way as the projections  74  engage facing surfaces of the gaps  41  to prevent longitudinal movement of the panels  15  in the direction A of  FIG. 1 . However, this is not a requirement. Also, where the plugs  76  and  84  have the same width dimension W 1  as the projections  74 , the plugs  76  and  84  might not contribute much to the resistance of longitudinal movement of the panels  15 , particularly where the dimension of the head  77  or  85  of the plugs  76  and  84  is small. Where the head dimension is larger, then the plugs  76  and  84  can contribute to the resistance of longitudinal movement. 
     The screen deck  10  can be assembled by first installing a full row of panels  15  at each of the feed and discharge ends of each fixing rail. These can be easily installed from above the screen deck  10  which is important for the safety of the installation personnel. The fixing members  20  can be fixed to the beams  11  loosely at first so that they can be shifted on the beams  11  to properly align the first rows of panels  15  as required. The side clamps can also be loosely fixed for later tightening. 
     With only the rows of panels at the feed and discharge ends of each fixing rail in place, there is space between the feed and discharge ends so that the installer has access to beneath the beams  11  to the nuts  48  to tighten the nuts and fix the fixing members  20  in place. Further rows of panels can be installed to the fixing rails between the initial rows at the feed and discharge ends and while there are still some panels absent from the deck, access to beneath the deck remains available. Thus, successive rows can be installed, all from above the deck. Prior to installing the final panels, the fixing members must be fully fixed in place while access to nuts  48  from above the screen deck remains available. This process can take place for all of the sets of fixing rails between the feed and discharge ends of the overall screen deck. 
     The edge panels can be slid in beneath the side clamps  21  so that the projections of the side clamps are received within the locating gaps of the panels. Once received, the opposite end of the panels can be fixed to a fixing member by the locking members  40 . The side clamps can be tightened when appropriate. 
     The above method of assembly allows the installation personnel to remain above the screen deck at all times and also allows the panels to be shifted slightly as they are positioned in the screen deck to ensure proper edge engagement with the side clamps and with adjacent panels. 
     The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the present disclosure.