Abstract:
An improved air supported impact section for air supported belt conveyors that includes a cushioned pad incorporated into the plenum plate to cushion the impact form and minimize damage to the air supported belt conveyors.

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 60/594,925, filed May 19, 2005. 

   FIELD OF THE INVENTION 
   The invention relates to an air supported impact section for air supported belt conveyors. Specifically, it relates to an improved impact section that minimizes damage to the conveyor belt. 
   BACKGROUND OF THE INVENTION 
   Conventional belt conveyors use idlers to support the length of the belt. The trough formed by the idlers and belt typically has a V-shape cross section for holding the material being carried along the belt conveyor. The V-shape cross section disadvantageously creates a pinch point at the bottom of the V-shape. Conventional belt conveyors also disadvantageously have belt sag between idlers and idler bumping causing material to be thrown up every time it goes over an idler, resulting in dust generations, product separation and degradation. 
   At the loading zones where material are loaded onto a belt conveyor, impact resulting from lump size, material density and height of material free fall could seriously damage the belt. In a conventional belt conveyor system, at the impact section, impact idlers are used. Impact idlers are generally cushioned to sustain the impacting force of dropped objects. 
   The vertical velocity of the material dropped from various heights above the belt surface and the horizontal belt speed will be different than the speed of the material when it contacts the belt, resulting in greater impact and shearing forces on the belt. Lumpy materials can cause appreciable impact on the belt. The heavier the lump, the greater height of fall or the greater its angular velocity when it contacts the belt, the greater will be the energy tending to rupture the belt. When the material strikes the belt directly over a conventional belt conveyor with idlers, damages to the carcass can result from the crushing action of the lump against the idlers. 
   Air supported belt conveyors (ASBC) overcome many of the disadvantages of conventional belt conveyors. As shown in  FIG. 1 , an ASBC  1  includes a large air chamber  2  with a curve plenum plate  3  forming the upper section of the air chamber  2 . Along the length of the plenum plate  3  are a plurality of holes  4 . A plenum bed  5  (i.e. belt) rests on top of the plenum plate  3  for holding the material  6  being carried along the ASBC. An ASBC may optionally include a roof cover (not shown). When air is blown into the air chamber  2 , air travels through the holes  4  forming a film of air between the plenum plate  3  and plenum bed  5 . The entire length of the plenum bed  5  and load of the ASBC is fully supported by a thin cushion of air and advantageously prevent belt sag and idler bumping of conventional belt conveyors. The curvature of the plenum plate  3  and plenum bed  5  also advantageously avoid pinching as in conventional belt conveyors. Further, the lack of idlers produces less friction than conventional belt conveyors. Because impact idlers are not used, there is a need for an improved impact section at the loading zone of an ASBC to minimize damage to the ASBC. 
   SUMMARY OF THE INVENTION 
   The present invention is an improved impact section that minimizes damage to the conveyor belt. In particular, an air supported impact section for ASBC. 
   The impact section of the present invention includes a cushioned pad incorporated into the plenum plate to cushion the impact force and minimize damage to the plenum plate, plenum bed, roof cover and carcass. The pad may be cast directly into the plenum plate during the manufacturing process. The pad may be made of urethane and absorbs most of the energy from the falling material. The pad has the same catenary curve profile as the plenum plate. A plurality of holes similar in size and spacing as those along the plenum plate are provided along the pad to provide continuous air film to support the plenum bed and load. Materials falling into the improved impact section of the present invention is immediately lifted and exited from the loading zone because the plenum bed is supported by a cushion of air and eliminates damages to both the plenum bed and plenum plate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention have been chosen for purposes of illustration and description and are shown in the accompanying drawings forming a part of the specification wherein: 
       FIG. 1  shows a cross sectional view of an air supported belt conveyor (ASBC). 
       FIG. 2  shows a perspective view of the air supported impact section of the present invention. 
       FIG. 3  shows a cross sectional view of the air supported impact section of the present invention. 
       FIG. 4  shows a top view of the air supported impact section of the present invention. 
       FIG. 5  shows a side view of the air supported impact section of the present invention. 
       FIG. 6  shows a perspective view of a removable air supported impact section of the present invention. 
       FIG. 7  shows a top view of the removable air supported impact section of the present invention. 
       FIG. 8  shows a side view of the removable air supported impact section of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to the drawing wherein the same reference number illustrates the same element throughout,  FIGS. 2-5  show an air supported impact section  10  of the present invention for an air supported belt conveyor (ASBC) such as that shown in  FIG. 1 . The air supported impact section  10  includes an air chamber  12  with a plenum plate  14  forming the upper section of the air chamber  12 . The plenum plate  14  has a curved profile, e.g. 20, 35, or 45 degrees. The plenum plate  14  has a plurality of equally-spaced holes  16  along the centerline where air is forced from the air chamber  12 . A plenum bed, i.e. belt (not shown), rests on top of the plenum plate  3  for holding the material being carried along the ASBC. 
   A section of the plenum plate  14  incorporates a rectangular shaped pad  18  that cushions the impact force from material dropped at the loading zone. The pad  18  may be made from a urethane, neoprene, or polymer material, etc. The pad  18  has the same catenary curve profile as the plenum plate  14 . Similar to the plenum plate  14 , the pad  18  has a plurality of equally-spaced holes  16  along the centerline to allow air to travel through to lift the plenum bed that rests on top of the pad  18 . The pad  18  may be molded directly into an opening of the plenum plate  14  during the manufacturing process. During the molding process of the pad  18 , a cover plate with pins that have the same diameter and spacing as the holes  16  on the plenum plate  14  is used. 
   Materials entering the ASBC are first directed to the air supported impact section  10 . The materials are channeled and directed to the pad  18  of the impact section  10 . Immediately after the materials fall onto the plenum bed, the cushion of air between the pad  18  and plenum bed lifts the material to allow the material to exit from the loading zone onto the ASBC, which eliminates damages to both the plenum bed and plenum plate  14 . 
   As shown in  FIGS. 6-8 , the air supported impact section  10 ′ has a pad  18 ′ that may be removably attached to the plenum plate  14  to facilitate replacement of a damaged or worn pad  18 ′. The pad  18 ′ has a circumferential edge  20  where a plurality of fastening means  22  are provided for removable attachment to an opening  24  of the plenum plate  14 . Fastening means  22  can be rivets, nuts and bolts, clamps, etc. 
   The size, shape and location of the pad  18  or  18 ′ on the plenum plate  14  may vary based on the particular application of the ASBC. The air supported impact section  10  or  10 ′ can be used for belt widths from 12″ to 120″. 
   Although certain features of the invention have been illustrated and described herein, other better modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modification and changes that fall within the spirit of the invention.