Abstract:
An impact bed for use with belt conveyors comprises a base frame having parallel, spaced-apart side members extending lengthwise where the side members have an arcuate, concave upper edge. Attached to the upper edge of the side members is an arcuate, concave plate having plural rows, each of a plurality of apertures or alternatively a plurality of tubes or channels having apertures may be used. Completing the assembly are a plurality of polymeric bars, with a smooth upper surface and a plurality of lugs dimensioned and spaced to fit into the plurality of apertures of one of the plural rows. The apertures and lugs are designed to interlock with one another such that no special tools are needed to remove the bars form the top plate when the bars become worn out. Channels having flex points may be used to support the bars. Idlers may be used on the supports.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application claims priority to U.S. Provisional Application Ser. No. 60/818,749, filed Jul. 6, 2006, the contents of which are incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to conveyor systems principally used in the mining and material handling industry, and more particularly to the design of conveyor loading zones, conveyor impact beds often referred to as an “impact saddle” often used to support a conveyor belt at a point where soil, rocks, gravel and other material drop onto a conveyor belt. 
   2. Discussion of the Prior Art 
   In the mining industries, conveyor systems are often used to move bulk material comprising dirt, ore, coal, tailings, etc. from one point to another. The bulk material may be dropped on to the moving conveyor belt from the bucket of a large power shovel or from the box of a dump truck from a considerable height above the level of the conveyor belt. Where the material to be conveyed includes heavy rocks and even boulders or the like, the impact of such objects striking the conveyor can rapidly damage a conveyor belt unless it is adequately supported from below. 
   To address this problem, conveyor system manufacturers produce and sell impact saddles to be used in heavy impact areas in which idler rollers are mounted in a frame so as to be rotatable by the friction drag imparted by the underside of the conveyor belt which the impact saddle supports. 
   When transporting loose materials, such as sand, gravel, dirt and rocks, the conveyor belt preferably has a concave curvature and, hence, the rollers comprising the impact saddle include a roller mounted on a horizontal axis and two side rollers that are inclined to the axis of the bottom roller. This configuration necessarily causes pinch points between the inclined rollers and the horizontal one. Such pinch points often result in premature belt failure. 
   Other known prior art impact cradles consist of a plurality of impact bars bolted to a framework which support a conveyor belt in generally the same shape as the conveyor idlers on the conveyor. The impact bars usually consist of extruded aluminum or formed steel “T” channels molded into a rubber or polymer impact absorbing material having a UHMWPE or Teflon upper sliding surface on which the conveyor slides. “T” bolts or other types of threaded fasteners are inserted into the “T” channel to fasten the bar to the underlying conveyor structure. A typical impact cradle of this type is shown in Andersson, U.S. Pat. No. 4,793,470 issued Dec. 27, 1988. 
   Other impact/slider bars may have no internal metal “T” slot and may be manufactured of a 100% polymer material, but still utilize a “T” slot molded into the bar in which a fastener is inserted to attach to the bar to the underlying conveyor structure. Some other systems are attached by drilling a hole through the impact bar and fastening the bar to the underlying conveyor structure with a countersunk bolt or fastener and then plugging the surface of the hole with a UHMW cap or another polymer material. 
   The problem with attaching impact bars with fasteners, nuts, bolts, etc., is that they are labor intensive to install and maintain, they can vibrate loose, rust or corrode and removing them often takes a cutting torch which can result in fires and added expense. Also, when there is internal metal in an impact/slider bar, if a conveyor wears through the polymeric sliding surface, metal may be exposed which may cause wear or grooving of the underside of the conveyor belt. Prior art impact and slider bars with internal metal are also more expensive to manufacture as more steps are needed to bond the metal to the polymer and metal add to the cost. Impact bars without metal are easier to recycle and less costly to dispose of. With many governmental agencies requiring separating of different types of materials that have to be disposed of for recycling or proper disposal, the present invention can provide substantial cost savings over many of the prior art systems. 
   Another type of impact cradle is shown in the Stoll/Richwood Industries U.S. Pat. No. 5,038,924, issued Aug. 13, 1991. Richwood uses a fastenerless system in which support frames, mounted in a transverse relation to the conveyor belt, are designed to support polymeric segments that are threaded onto the frames to support the conveyor and act as a wear and impact surface. This system has advantages over some of the prior art as it eliminates the use of many of the troublesome fasteners, but it still has shortcomings in that it is not easy to inspect worn segments, is not easily adjustable for wear or is not easily adaptable to many of the low profile or specially designed conveyor systems (e.g. underground coal mining tailpiece loading stations) in the conveyor and material handling industry. The segments are also sometimes difficult to slide on as the friction between the often heavy belt, the segments and the mounting frame has to be overcome when threading the segments onto the frame. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved impact and slider bar design and mounting method that can be adapted to a wide variety of conveyor loading zones, impact zones and slider beds. The impact bars can be easily and quickly installed, removed or maintained without tools or fasteners in a fraction of the time when compared to most of the prior art systems now used. The design of the present invention allows the impact slider bars to be securely attached to the corresponding surface without any internally molded metal channels as in prior art systems. The composite or polymer impacting bars are sufficiently flexible so that they can conform to a variety of concave or convex or irregular surfaces. This is a great advantage over prior art systems, especially in designing transition areas for conveyor loading zones. Transition areas typically occur at elevation changes (e.g., between a tail-pulley of a first conveyor and the first troughing idlers of a second conveyor, or between horizontal runs and inclined runs of a conveyor system). 
   The improved invention consists of an impact slider bar with an upper exposed portion consisting of a low friction polymer sliding surface, an intermediate cushioning layer for impact resistance and a lower attachment layer with a plurality of lugs projecting outwardly from the bar&#39;s lower surface. The lower attachment layer preferably consists of a fiber-reinforced rubber material in the 80 to 90 durometer range. Other comparable hardness polymers such as a polyurethane compound may be used. 
   The lugs of the impact slider bar correspond with and fit into a row of apertures in an arcuate mounting plate, surface or channel. The apertures in the mounting plate, surface or channel are preferably “T” shaped slots that are formed through the thickness of the channel. The lugs on the lower attaching surface of the impact bar are generally rectangular in cross section but are undercut along opposed sides thereof. This allows the lugs to be inserted into the corresponding T-shaped apertures at the top of the “T” and then displaced longitudinally so that the bars become captured in the stem of the “T”, locking the slider bars to the arcuate steel mounting plate in parallel rows. A locking mechanism on the underside of the mounting plate, such as a strap inserted into a recess on one side with a hitch pin on the other, can be used to prevent the bar or bars from sliding back out if desired. The locking mechanism would hold one or more of the “T” lugs of the impact bars into the narrow stem portion of the “T” apertures in the mounting plate. 
   The invention can be adapted to be used with U-channel retrofit systems, curved profile systems, drop-down wing type systems, simple flat plates for flat conveyors, or a curved profile mounting plate consisting of a press-broken or rolled plate formed to achieve the desired curve to match the trough of the conveyor with which the impact saddle is to be used. 
   The flexibility of the impact/slider bars of the present invention is of great advantage when a change of elevation or angle is needed at a transition zone, e.g. between the tail pulley and the impact zone at a conveyor loading zone. Here, the mounting plates or surfaces can be “hinged” allowing the curvature to be adjusted to varying angles to conform to the belt as the angle between the tail pulley and load zone changes. The improved impact bar, with no internal metal, can easily be made to conform to different conveyor curvatures as the mounting surfaces are pivoted at the “hinged” locations. 

   
     DESCRIPTION OF THE DRAWINGS 
     The foregoing features and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. 
       FIG. 1  is a perspective view of a preferred embodiment of the impact saddle of the present invention; 
       FIG. 2  is a perspective view of the impact saddle of the  FIG. 1 , but with several bars removed; 
       FIG. 3  is a cross-section taken through one of the bars; and 
       FIG. 4  is a bottom view of a mounting plate with a slider bar attached. 
       FIG. 5  is a cross sectional end view of a conveyor system. 
       FIG. 6  is a perspective view of a tube and elastomeric bar. 
       FIG. 7  is a front view of an adjustment device. 
       FIG. 8  is a perspective view of the side member attachment method. 
       FIG. 9  is a side cut-a-way view of the side member showing the locking bar in the impact bed; 
       FIG. 10  is a section of the impact saddle of the  FIG. 1 , with a plurality of tubes replacing the plate. 
       FIG. 11  is a section of the impact saddle of the  FIG. 1 , with a plurality of channels with flex points replacing the plate. 
       FIG. 12  is a section of the impact saddle having bars with idlers. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring first to  FIG. 1 , there is indicated generally by numeral  10  an impact bed constructed in accordance with the present invention. It is seen to comprise a base made up of first and second pairs of steel channel members or base rails, the first pair including channel members  12  and  14  and the second pair including channel members  16  and  18 . These channel members extend horizontally the width dimension of the impact bed. Sandwiched and clamped between the channels  12  and  14  are upwardly projecting legs  20  and  22 . Likewise, clamped between the channel members  16  and  18  are an upright leg  24  and another leg that is hidden from view in  FIG. 1 , but which extends directly across from the leg  22 . 
   Channel members  12 ,  14 ,  16 ,  18 , are used to support arcuate side plates  30  and  34 . As best seen in  FIG. 7 , in order to adjust the height of arcuate plates  30  and  34  adjustment devices  25  are attached to the channel members  12 ,  14 ,  16  and  18 . The channels have oblong apertures  31  cut in them. The height adjustment devices  25  having teeth  21  are attached to the channels. Plate  27  having teeth  23  are inserted into adjustment device  25  at the desired height and their teeth  21 ,  23  engage to prevent vertical movement of plate  27  in plate  25 . In this manner it is easy to adjust the height of bolt holes  29  and thus the height of the ends of side members  30  and  34  which are secured by bolts  26 ,  28 , and  38  as seen in  FIGS. 1 and 2 . 
   Side members  30  and  34  have a horse shoe bolt engaging member  39  for engaging bolts  26  and  28 , as best seen in  FIG. 8 . When it is desired to attach or remove the saddle segments  32 ,  36 , or elastomeric bars  44 , the saddle segments can be slid into or out of the impact bed  10  with side members  30  or  34  sliding between channel members  12 ,  14 , and  16 ,  18  while the side members  30 ,  34  laying down until the open end of the house shoe bolt attachment  39  engages one of bolts  26  or  28 . Then the side member  30  or  34  is lifted at the other end and bolted with bolt  38  to one of legs  20  or  22 . When lifted the horse shoe opening is angled downward and the legs  20 ,  22  are attached preventing the horse shoe opening from lifting off of the bolts  26 ,  28 . It is preferred to have a rubber cushion  37  in the house shoe bolt attachment  39  for engaging bolts  26  or  28 . As seen above the height of the legs  20 ,  22  and the height of bolts  26  and  28  are adjustable on the channel members  12 ,  14 ,  16  and  18  by the attachment plates  25  and plates  27 . In this manner the saddle segments  32 ,  36  are quickly and easily installed and adjusted to the desired height. Similarly the saddle segments can easily be removed access to the elastomeric bars  44  for maintenance and replacement. 
   Although not seen in the view of  FIG. 1 , side members along the rear edges of the saddle segments  32  and  36  are captured between the channel members  16  and  18  and held by bolts in the same way that the arcuate side members  30  and  34  are secured to the channels  12  and  14 . 
   The outer end of the side member  30  is fastened to the upper end of the leg  20  by a bolt  38  and, similarly, the outer end of the side plate  34  is bolted to the upper end of the leg  22 . In an identical manner, the outer ends of the rear side plates are secured to the upwardly extending legs, as at  24 . 
   Referring now to  FIG. 2 , each of the saddle segments  32  and  36  includes a concave steel plate  40 , that is rolled or otherwise formed so as to conform to the contour of the upper edges of the arcuate side plates  34 , and the end portion  42  thereof is bent downward so as to abut the end edges of the side plates. The plate  40  is preferably welded along the opposed edges thereof to the end plates  34 . It is preferred that each segment of plate  40  containing a row of apertures  43  be flat to hold the bars  44  flat. The segments have a bend therebetween thus approximating a curved concave surface. 
   Laser-cut or otherwise formed through the thickness dimension of the arcuate plate  40  are a plurality of apertures of a predetermined shape with T-shaped apertures  43  being preferred. The apertures are here shown as arranged in parallel rows of three apertures each. In the embodiment shown the first aperture  43  in each row extends inward from the end of the support which can be the curved plate  40  or the tube  60 . The apertures in each row are spaced apart by the same predetermined distance and are used to secure elastomeric bars  44  to the exposed upper surface of the panels  40  in a manner to be described below. In addition to tubes  60 , channels  64 , essentially half tubes, can be used instead of tubes to support apertures  43  as shown in  FIGS. 4 ,  10 ,  11 , and  12 . 
   The bars themselves may be constructed as illustrated in the cross-sectional view of  FIG. 3 . Each of the bars  44  is preferably, but not necessarily, of a laminated construction wherein a first layer  46  may comprise an ultrahigh molecular weight (UHMW) polymer, such as polyurethane or polyethylene. The layer  46  is adhered to a cushioning layer  48  which may typically have a durometer rating in the range of from 40-60 Shore A. The UHMW layer  46  may be either cold-bonded to the cushioning layer  48  with a suitable adhesive or, alternatively, the two layers may be vulcanized-bonded in a hot press. The cushioning layer  46  is also appropriately bonded to a base layer  50  which is preferably a harder polymer that is impregnated with fibers to give it an increased strength and tear resistance. Rather than having the described laminated construction, the bars may also be a solid polymer, such as polyurethane or polyethylene. 
   Formed on the undersurface of the bars  44  are a plurality of projections, as at  52 , equal in number to the number of apertures in a given row of the apertured plate  40 . The lugs  52  project downward from the undersurface  54  of the bar  44  and are undercut as at  56  along side edges thereof to define shoulders  58 . 
   The lugs  52  have a length and a width dimension allowing them to readily pass through the head portion of the T-shaped slots. Now, when the bar is displaced along its longitudinal axis, the lug  52  will be captured in the stem of the “T” in that the edges defining the stem of the “T” project into the undercut area  56  of the lugs. The bars become locked to the apertured plate  40 . While projections of rectangular cross-section for fitting into “T” slots is preferred, other shapes can be used as well, so long as the apertures include an opening of a predetermined size contiguous with a slot whose width is less than the size of the opening and the projection has a neck zone for fitting into the slot. 
   The lugs  52  can be locked in place by bar  82  inserted into brackets  84  as shown in  FIG. 9  such that bars  44  will not slide out of slots  43 . 
   In use, the impact bed  10  is placed beneath a conveyor belt with the belt running parallel to the length dimension of the bars  44 . The impact bed is positioned such that the stems of the T-notches are oriented in a downstream direction, such that friction between the moving conveyor belt and the bars tends to urge the bars deeper into the stem of the “T”. 
   When the bars become worn, removal and replacement thereof can be accomplished without need for any special tools. A maintenance person need only strike the bars with the heel of his hand in an upstream direction relative to the conveyor belt until the lugs  52  are again aligned with the head portion of the T-shaped aperture. This then allows the bar to be lifted free from the arcuate panels  40  of the impact bed frame and replaced with another. 
   In order to have easy access to the bars  44  the legs  20 ,  22  can be detached by removing bolts  38  and the side members  30 ,  34  can be lowered providing more space between the bars  44  and the conveyor belt for easier removal of the worn bars  44  and easier replacement with newer bars. Increased access to the bars  44  particularly near the horse shoe bolt attachment  39  end of saddle segments  32 ,  36  can be had by removing bolts  26  or  28 , disconnecting the legs  20 ,  22  and sliding the saddle segments out from under the conveyor belt  80 . 
   In another embodiment as shown in  FIG. 5  a conveyor system having standard rollers  70  supported on brackets  72  supports the conveyor belt  80 . However rather than having rollers on the sides of the belt  80  a sliding surface  46  on top of elastomeric bars  44  is used to support belt  80 . The cross section of the elastomeric bar  44  is shown in  FIG. 3 . In this embodiment the elastomeric bar  44  engages a tube  60  having slots  43  as shown in  FIG. 6 . The tubes  60  can be rectangular tubes which engage the T shaped projections  52  under elastomeric bars  44  as shown in  FIG. 6 . The projections  52  lock the elastomeric bar  44  in place when inserted into the T shaped head and moved to the stem of the T shaped slot. A pin  55  can be inserted into the tube  60  to lock the elastomeric bars in place. A wire  53  may be used with the pin  55  to secure the pin in the tube  60 . Alternatively a plug  86  can be inserted in an aperture behind bar  44  to lock it in place. 
   The tube  60  can be placed on a bracket  67  at the end of leg  20  to hold the tube  60  in the desired location for supporting belt  80 . The brackets  67  may be adjustable to hold the tubes  60  in the desired place. The brackets  67  may be wider than shown and hold two or more tubes  60 . The tubes  60  can be attached to the brackets  67  by bolts  65  accessible through slots  43 . 
   The elastomeric bars  44  may be easily and quickly installed or removed from slots  43  in tubes  60  and replaced when they become worn. 
   The tubes  60  can also be placed on the sides of a conveyor belt  80  where the impact saddle has a base with side members  30 ,  34  but requires further support on the sides as provided by tubes  60  in  FIG. 5  where the rollers  70  are replaced by side members  30 ,  34 . 
   In an alternative embodiment shown in  FIG. 10  side members  30 ,  34  have indented slots  62  for inserting tubes  60  to form a strong support structure for holding bars  44  in place. 
   In another alternative embodiment as shown in  FIG. 11  tubes  60  are replaced by C-shaped channels  64 . The channels  62  may have one or more flex points where the channels are joined together as shown at  FIG. 4 . In  FIG. 4  the plates  69  joint C-shaped channels  64  together at selected adjustable angles. Alternatively the channels  64  may be permanently attached such as by welding at predetermined angles. As shown in  FIG. 11  the angle the channels come together at form an apex at the flex point  68 . This can be used where for example a conveyor belt has a change of direction from going uphill at one rate of inclination to another rate of inclination or for a flex point of a conveyor belt going from uphill to downhill. Obviously the flex point can be angled the other way so that instead of an apex a trough is formed. There may be more than one flex point  68  along the bars  44  for a smother transition in changes of direction. The bars  44  are flexible and can be installed or removed without changing the angles on the channels  64  or the channels  64  can be made flat for easier installation or removal of the bars  44 . 
   In another embodiment idlers  92  can replace the top surface of bars  44 . As shown in  FIG. 12  the bar  94  can have a plurality of idlers on it or alternatively one idler in the section over one lug for installing one idler at a time with the remainder of the row of slots having a bar with a smooth top surface. Or one idler  92  can be at a flex point on the bars  44 . 
   The idlers  92  are supported on arms  97  attached to a base  94  having lugs  52  as in a standard bar. 
   The idlers  92  on the outside edges of the conveyor belt  80  can support the conveyor at a different angle for additional material handling ability of the conveyor belt system. 
   In other embodiments idlers  92  can be used bars  44  on the outside most bars  95  as shown in  FIG. 1  under conveyor belt  80 . The outer most bar  95  may be angled at a steeper angle such that the belt is flexed more and idlers  92  are required. 
   The impact bed may have various combinations of bars with smooth surfaces, bars with idlers, bars held by tubes with apertures, channels with apertures or sheets with apertures. The impact beds may have central portions with rollers or idlers thereunder or the elastomeric bars with a smooth surface. Many different combinations are possible depending on the needs of the conveyor system. 
   It can be seen, then, that the present invention provides an impact bed for a conveyor system that does not require bolts or any other metal fastening mechanisms built into the bars. This feature permits more environmental-friendly disposal in that the elastomeric material employed can be recycled. Moreover, because the absence of such metal parts as metal T-channels and T-bolts, there is less of a chance of sparks being generated upon impact by a boulder, sparks could be a problem in the coal mining application where methane gas buildup is frequently a problem. 
   This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.