Patent Publication Number: US-8123043-B2

Title: Screening module retaining assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This claims priority to Australian Application No. 2006243879, filed Nov. 28, 2006 which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     This invention relates to ore screening systems. More particularly, the invention relates to a screening module retaining assembly and to a screening system including such retaining assembly. 
     BACKGROUND TO THE INVENTION 
     Screening systems are used for classifying ores. These screening systems use foraminous screening modules which pass material of a predetermined size and block material of larger size. 
     The screening modules are removably attached to a screen deck as they wear rapidly and need to be replaced. Various forms of attachment are used for attaching screening modules to the screen deck. These forms of attachment include rails, pins, or other attachment elements which releasably retain the screening modules on the screen deck. 
     One problem with these different arrangements is that, if the screen deck is configured to have screening modules with an attaching system of a first type attached to the screen deck, the screen deck cannot be used with screening modules of a type having a different attaching system. 
     In certain situations, the means by which the screening modules are attached to the screen deck stand proud of an upper surface of the screening modules. A problem with this arrangement is that it reduces the screening area of the screening modules and impedes flow of material over the upper surfaces of the screening modules. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, there is provided a screening module retaining assembly which includes: 
     a body member defining a passage, the body member further including a locating formation, associated with a first end of the body member, for engaging a screening module to assist in retaining the screening module relative to a screen deck; and 
     a retaining element displaceably arranged in the passage, the retaining element being displaceable between a first, non-retaining position in which the retaining element is accessible from the first end of the body member and a second, retaining position in which the retaining element is received within the passage and acts on at least a part of the body member for retaining the body member in position relative to a component of the screen deck, a head portion of the retaining element defining a receiving formation for receiving a complementary formation of the screening module, when the retaining element is in its second position, to assist in laterally retaining the screening module relative to the screen deck. 
     The body member may be a moulding of a resiliently flexible material. For example, the body member may be a moulding of a polymeric material such as a polyurethane material. 
     The body member may comprise a boss which defines the first end of the body member. A screen deck engaging assembly may extend from, and be formed integrally with, the boss. A free end of the engaging assembly may define a second end of the body member. The passage may be an open passage extending from the first end of the body member to the second end of the body member. The retaining element may be at least the same length as the body member and, possibly, longer so that, when the retaining element is driven into its second, retaining position relative to the body member, a distal portion of the retaining element projects beyond the second end of the body member. 
     The engaging assembly may comprise a plurality of engaging elements, each being in the form of a wing. The wings may be separated from each other by slots extending from the second end of the body member towards the first end of the body member, terminating short of the boss of the body member. 
     In one embodiment, the locating formation of the body member may be in the form of a radially outwardly extending lip defined at, or adjacent, the first end of the body member, the lip engaging a complementary recess of the screening module. 
     The receiving formation of the retaining element may be in the form of a socket defined in the head of the retaining element. 
     The complementary formation of the screening module may be in the form of a lug received in the socket. It will be appreciated that, in use, two screening modules are arranged side by side over the retaining assembly. Thus, each lug may be semicircular in cross section to form, together, a spigot which is a snug fit in the socket in the head of the retaining element. 
     According to a second aspect of the invention, there is provided a screening system which includes: — 
     at least one retaining assembly, as described above, mountable to an underlying rail of screen deck; and 
     at least one screening module releasably attachable to the at least one retaining assembly, the screening module including a frame portion mountable on the body member of the at least one retaining assembly, the frame portion having a recess to receive a part of the body member and an engaging formation which engages the head of the retaining element of the retaining assembly, the screening module further including a screening panel portion carried by the frame portion. 
     The frame portion may include a recess proximate each corner of the frame portion so that the frame portion can be mounted in any desired direction on the screen deck. In use, each of two opposed sides of the frame portion may be secured to an underlying rail of the screen deck by a pair of spaced retaining assemblies. Each retaining assembly may be received in a recess in the frame portion. 
     The frame portion may include a recess proximate each corner of the frame portion so that the frame portion can be mounted in any desired direction on the screen deck. 
     Preferably, the frame portion comprises an intermediate frame to which the screening panel portion is releasably attached. An upper surface of the intermediate frame may carry a clip formation on which the screening panel portion is releasably clipped, for use. Thus, it will be appreciated that the screening panel can be a tear-off type panel to render it readily replaceable without disturbing the underlying intermediate frame or the retaining assemblies securing the intermediate frame to the screen deck. 
     The screening module may be square in plan view. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       An embodiment of the invention is now described by way of example with reference to the accompanying drawings in which: 
         FIG. 1  shows a three dimensional view of an embodiment of a screening module retaining assembly; 
         FIG. 2  shows a side view of a part of the assembly of  FIG. 1 ; 
         FIG. 3  shows a plan view of the part of  FIG. 2 ; 
         FIG. 4  shows a sectional side view of the part taken along line IV-IV in  FIG. 3 ; 
         FIG. 5  shows a plan view of part of an embodiment of a screening system; 
         FIG. 6  shows an end view of the part of the screening system of  FIG. 5 ; 
         FIG. 7  shows a three dimensional view of a part of the screening system during assembly; and 
         FIG. 8  shows a sectional side view of a part of the screening system. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT 
     Referring initially to  FIGS. 1 to 4  of the drawings, an embodiment of a screening module retaining assembly is illustrated and is designated generally by the reference numeral  10 . The module  10  includes a body member  12  defining a passage  14 . The body member  12  further includes a radially outwardly extending locating formation in the form of a lip  16  at a first end  18  of the body member  12 . As will be described in greater detail below, the lip  16  engages a screening module of a screening system to assist in retaining the screening module relative to a screen deck. A retaining element in the form of a socket head cap screw  20  is displaceably received in the passage  14  of the body member  12 . The cap screw  20  is displaceable between a first, non-retaining position in which the cap screw  20  is accessible from the first end  18  of the body member  12  and a second, retaining position, as shown in  FIG. 8  of the drawings, in which the cap screw  20  is received within the passage  14  of the body member  12 . 
     To accommodate a head  22  of the cap screw  20 , an operatively upper end of the passage  14  is counterbored as shown at  24  in  FIGS. 2 and 4  of the drawings. 
     The body member  12  of the assembly  10  comprises a boss  26  defining the first end  18  of the body member  12 . The body member  12  further includes a screen deck engaging assembly  28  extending from the boss  26 . The screen deck engaging assembly  28  is in the form of a pair of opposed engaging elements, each in the form of a wing  30 . The wings  30  are arranged diametrically opposed to each other and are separated from each other by a pair of opposed longitudinally extending slots  32 . The slots  32  extend from a second end  34  of the body member towards the first end  18  of the body member  12  terminating short of a lower edge  36  of the boss  26 . It is also to be noted that the passage  14  tapers inwardly towards the second end  34  of the body member  12  as shown at  38  in  FIGS. 2 and 4  of the drawings. This assists in causing flaring of the wings  30  of the engaging assembly when the cap screw  20  is displaced from its first position to its second position. 
     The body member  12  is a one-piece moulding of a suitable resiliently flexible material. More particularly, the body member  12  is a moulding of a polymeric material such as a polyurethane material having the required Shore hardness. 
     The cap screw  20  defines an Allen key recess or socket  40  in its head  22 . The socket  40  serves as a receiving formation for receiving a complementary formation of a screening module of the screening system as will be described below with reference to  FIGS. 5 to 8  of the drawings. 
     Referring now to  FIGS. 5 to 8  of the drawings, an embodiment of a screening system is shown and is illustrated generally by the reference numeral  50 . The screening system  50  comprises a screen deck  51  on which a plurality of screen deck rails  52  are arranged in parallel, spaced relationship. Apertures are defined at longitudinally spaced intervals along each rail  52 . Each aperture is dimensioned to receive the engaging assembly  28  of a retaining assembly  10  through it. 
     The screening system  50  further includes a plurality of screening modules  54  which are arranged in side-by-side relationship on the rails  52  as shown in  FIG. 5  of the drawings. It is to be noted that, in respect of each of modules  54 . 1 , a screening panel  56  of the screening module  54  is omitted to show the mounting of a frame portion in the form of an intermediate frame  58  on the rails  52 . 
     In this embodiment, each screening module  54  comprises the intermediate frame  58  on which the screening panel  56  is removably received. For this purpose, a periphery of each intermediate frame  58  of each module  54  carries a clip formation  60 . The clip formation  60  is received in a complementary recess  62  in a periphery of the screening panel  56  for enabling the screening panel to be removably mounted on its associated frame  58 . In other words, the screening panel  56  is a tear-off element and can be replaced without replacing the underlying frame  58  of the screening module  54 . It will be appreciated that the screening module  54  could be of a unitary construction, i.e. that the screening panel portion  56  is formed integrally with the frame portion as a one piece moulding or as two separate mouldings that are subsequently bonded fast with each other. 
     Each screening module  54  is substantially square in plan view and has dimensions of roughly 300 mm by 300 mm. Each side  64  of each intermediate frame has a pair of spaced recesses  66  so that the intermediate frame  58  can be mounted in any desired orientation on the underlying rails  52 . Thus, the screening modules  54  can be arranged in a with-flow arrangement on the screen deck  51  or in a cross-flow arrangement. Instead, dedicated with-flow, cross-flow or heavy duty modules  54  can be provided with recesses  66  in the appropriate sides  64  of the intermediate frame  58 . 
     Each recess  66  is shaped to accommodate approximately half of the boss  26  of the body member  12  of an underlying retaining assembly  10  in it. As shown in greater detail in  FIGS. 7 and 8  of the drawings, a downwardly extending lug  68  projects into the recess  66  of the frame  58 . This lug  68  is received in the socket  40  in the head  22  of the cap screw  20 . 
     Thus, in use, a retaining assembly  10  is inserted into one of the apertures in the rail  52  with the cap screw  20  in the position shown at  20 . 1  in  FIG. 7  of the drawings. The cap screw  20  is then driven home to the position shown at  20 . 2  in  FIG. 7  of the drawings where a distal part of a shank  70  of the cap screw  20  projects beyond the second end  34  of the body member  12  of the assembly  10 . As the screw  20  is driven from the position shown at  20 . 1  to the position shown at  20 . 2  in  FIG. 7  of the drawings, it causes the wings  30  of the engaging assembly to flare outwardly due to engagement of the tapered part  38  of the passage  14  by the shank  70  of the cap screw  20 . This serves to anchor the body member  12  in position on the rail  52 . 
     An intermediate frame  58  is mounted on a pair of the assemblies  10  on each of a pair of adjacent rails  52  of the screen deck  51 . The lip  16  of each body member  12  engages a shoulder formation  72  in the associated recess  66  of the intermediate frame  58 . This serves to locate the frame  58  relative to the assemblies  10  and, therefore, relative to the intermediate rails  52  of the screen deck  51 . 
     In addition, the lug  68  is received in the socket  40  of the head  22  of the cap screw  20 . The lug  68  is semicircular in cross-section and, when two intermediate frames  58  are arranged side by side as shown in  FIG. 7  of the drawings, two lugs  68  together, make up a spigot which is a snug fit in the socket  40  of each screw  20  of the pair of assemblies  10 . The lugs  68  serve to locate the intermediate frames  58  of the screening modules  54  laterally with respect to each other and to improve the integrity of the mounted screening modules on the rails  52  of the screen deck  51 . 
     It is an advantage of the invention that a screening system  50  is provided which is more versatile in that, by use of the retaining assemblies  10 , a screen deck can be modified to accept screening modules  54  which are either of the pin attaching type or of the rail/clip attaching type. Hence, with the provision of the retaining assemblies  10 , screening modules  54  can be used with either a pin-type screen deck or a rail-type screen deck. In addition, the use of a cap screw as the retaining element improves the strength of the retaining assembly  10  and, as a result, improves the lateral retention of the screening modules  54  on the rails  52  of the screen deck. 
     Still further, the assembly  10  can be provided with the cap screw  20  partially driven into the passage  14  so that threads of the screw bite into the wall of the passage  14  to retain the cap screw  20  in its first position relative to the body member  12  of the assembly  10 . In this way, the likelihood of losing the screw, prior to use, in the hostile environment in which the screens decks are often used is reduced. 
     It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.