Abstract:
A skirt board and mounting plate for sealing the side edges of a conveyor belt to prevent spillage of material being transported. The skirt board comprises an elastomeric sheet having regularly spaced parallel ribs integrally formed on one major surface thereof and adapted for insertion within regularly spaced parallel slots formed in a metal mounting plate that is adapted for attachment to a frame disposed above or along side the conveyor belt.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to materials handling equipment, and more particularly to the design of side curtains for use with conveyor belts used for transporting bulk materials for inhibiting spillage of the granular material. 
     II. Discussion of the Prior Art 
     Rubberized fabric conveyor belts are commonly used for transporting bulk materials, such as sand, gravel, iron ore, taconite and similar materials. Likewise, conveyor belts are commonly used in the grain milling industry for transporting granular materials. 
     A problem often arises at a location along the conveyor belt where the bulk material of the type described is dispensed from a hopper or chute onto the conveyor belt because of a tendency for the bulk material to overflow the side edges of the conveyor belt. This is especially true if the flow rate from the hopper is not properly matched to the speed of the conveyor belt. To avoid the attendant mess and need for frequent cleanup, an economical means must be provided for inhibiting spillage of the bulk material off from the side edges of the conveyor belt onto which the bulk material is being deposited. 
     The prior art teaches a variety of conveyor belt side curtains, also commonly referred to as skirt boards, and in this regard, reference is made to the Stahura U.S. Pat. No. 4,236,628, which became Reissue U.S. Pat. Re. No. 31,249. It comprises a plurality of relatively narrow (6″ wide) interlocking skirt board sections having dove-tail grooves formed therein so as to mate with corresponding dove-tail shaped, outwardly projecting ribs on a mounting plate. The interlocking skirt board members have a lower edge that is adapted to cooperate with a moving conveyor belt when the mounting plate is appropriately suspended from a frame system. The narrow rubber blocks comprising the skirt members fail to properly seal in that the blocks tend to fall off their mounts and leakage occurs at the numerous joints. Other patents directed to conveyor belt side curtains include deRooy U.S. Pat. No. 5,303,813, Mott U.S. Pat. No. 5,154,280, Swinderman U.S. Pat. Nos. 5,048,669 and 4,874,082, Gordon U.S. Pat. No. 4,231,471, and Klegg U.S. Pat. No. 3,499,523. 
     Each of these patents describes side curtains or skirt boards having a stationary mounting plate and a displaceable skirt whose lower edge is brought into contact with a moving conveyor belt to inhibit spillage of granular material off the sides of the conveyor. The need still exists, however, for a less expensive skirt board design that provides ease of mounting relative to a conveyor system and ease of adjustment of the skirt board member at periodic intervals to accommodate wear of the skirt board and an ability to conform to curves in conveyor belts such as commonly occurs at transition areas where the belt leaves a tail pulley and crosses an adjacent troughing roller. The present invention provides such an improvement. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a conveyor belt skirt board apparatus that includes a generally rectangular mounting plate of a predetermined thickness and having an upper edge, a lower edge and opposed side edges. The mounting plate is adapted to be suspended from a frame structure that is aligned parallel to side edges of an endless conveyor belt. The mounting plate includes a plurality of regularly spaced, parallel slots of a predetermined width that are formed inward from the lower edge thereof and through its predetermined thickness so as to extend toward, but short of its upper edge. The mounting plate is bent and an angle of about 90° along a line extending between the opposed side edges thereof, the line intersecting at least a portion of each of the parallel slots such that the bent upper portion of the mounting plate includes a plurality of apertures, each contiguous with one of the plurality of parallel slots. 
     The apparatus further comprises a generally rectangular elastomeric skirt member having first and second major surfaces, a lower edge, an upper edge and opposed side edges. The width of the skirt member spans a plurality of the slots on the mounting plate. The first major surface is generally planar and the second major surface has a plurality of integrally formed, outwardly projecting, compressible, parallel ribs of predetermined thickness and width and the same regular spacing as the regular spacing between the parallel slots formed in the mounting plate. The predetermined thickness of the ribs is less than a corresponding dimension of the aperture in the mounting plate and the width of the ribs is slightly greater than the width of the slots in the mounting plates such that when the ribs are inserted through the apertures and squeezed into the slots in the mounting plate, the skirt member is suspended on the mounting plate with a predetermined friction force. 
     By serrating the edges of the parallel slots in the mounting plate, upward displacement of the skirt member relative to the mounting plate is inhibited. 
    
    
     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 partial perspective view showing conveyor side curtains of the present invention affixed to the mouth of a chute through which granular material is deposited on a moving conveyor belt; 
     FIG. 2 is a front plan view of a skirt board assembly; 
     FIG. 3 is a top plan view of FIG. 2; 
     FIG. 4 is a left end view of the skirt board assembly; 
     FIG. 5 is a cross-sectional view taken along the line  5 — 5  in FIG. 1; 
     FIG. 6 is a cross-sectional view taken along the line  6 — 6  in FIG. 5; and 
     FIG. 7 is a partial side elevation of a skirt board mounting plate adapted to be used proximate a transition zone on a conveyor belt. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the device and associated parts thereof Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import. 
     Referring first to FIG. 1, there is indicated generally by numeral  10  a conveyor system for transporting granular material and incorporating the skirt boards constructed in accordance with the present invention. The conveyor assembly includes an endless belt  12  having an upper flight  14  and a lower flight  16 . The belt is deployed about and end roller  18  and another end roller (not shown) with additional spaced rollers  20  supporting the upper flight  14  and rollers  22  supporting the lower flight  16 . 
     Positioned above the upper flight  14  of the conveyor belt  12  is a hopper  24  terminating in a chute  26 . Granular material flowing down the hopper  24  and out the chute  26  is intended to land on the upper flight  14  of the conveyor belt. Skirt boards  28  are mounted relative to three sides of the chute  26  to prevent spillage of the granular material off the rear and side edges of the conveyor belt&#39;s upper flight  12 . 
     Referring next to FIGS. 2 and 3, the skirt board assembly  28  is seen to comprise a mounting plate  30  and a molded elastomeric skirt member  32 . The mounting plate may be generally rectangular and may have an upper edge  34 , a lower edge  36  and opposed side edges  38  and  40 . The mounting plate for use in a straight section of the conveyor includes a plurality of regularly spaced, parallel, slots  42  of a predetermined width that are formed inward from the lower edge  36 , through the thickness dimension of the plate and that extend toward, but short of, the upper edge  34 . 
     As best seen in FIG. 4, the mounting plate  30  is bent at an angle of about 90°, as at  44 , along a line extending between the opposed side edges  38  and  40 . As best seen in FIGS. 2 and 3, the bend or fold line intersects at least a portion of each of the parallel slots such that the upper bent portion  46  of the mounting plate  30  includes a plurality of apertures, as at  48  in FIG.  3 . Each of the apertures is contiguous with one of the plurality of parallel slots  42 . 
     The mounting plate  30  is preferably made from sheet metal in a stamping operation. Stainless steel about ⅛ inch thick is preferred. Following the stamping operation, the sheet is bent in a metal break. As such, the mounting plate can be very economically fabricated. The die used in stamping is constructed so as to provide a serrated edge to the metal defining the parallel slots  42  along the entire length of those slots. 
     With continued reference to FIGS. 2 and 3, the elastomeric skirt member  32  has an outer major surface  50  and an inner major surface  52  and with a lower edge  54  and an upper edge  56 . The first major surface  50  is generally planar while the second major surface has a plurality of integrally formed, outwardly projecting, compressible, parallel ribs  58  of a predetermined thickness and width and with the same regular spacing therebetween as the regular spacing between the parallel slots  42  formed in the mounting plate  30 . The thickness dimension of the ribs, i.e., the extent of projection thereof beyond the second major surface  52 , is designed to be slightly less than the corresponding dimension of the apertures  48  formed in the mounting plate while the width of the ribs is slightly greater than the width of the slots  42 . Hence, when the ribs are inserted through the apertures  48  and guided into the slots, the ribs are squeezed so as to hold or support the skirt member  32  on the mounting plate with a predetermined friction force. The serrations on the edges of the slots  42  are formed so as to inhibit upward movement of the skirt member  32  relative to the mounting plate  40 . It is apparent, however, that if a force is applied to the upper edge  56  of the skirt member  32  that is greater than the frictional forces between the ribs  58  and the side edges of the slots  42 , the skirt member can be moved downwardly. 
     The skirt member  32  may be fabricated from polyurethane or other suitable plastic, but a fiber or cord reinforced rubber is perhaps preferred. Its width is such that it will include a plurality of parallel ribs  58  and will span a corresponding plurality of the slots on the mounting plate. 
     Referring next to FIG. 5, the mounting plate  30  is preferably attached to the outer side wall of the chute  26  by welding the two together along the upper edge  34  of the mounting plate and following this attachment, the skirt members  32  may be applied to the mounting plate by guiding the ribs  58  through the apertures  48  and into the parallel, serrated slots  42  of the mounting plate. The skirt member  32  is then forced downward by hammering on the upper edge  56  thereof until the lower edge  54  is made to engage the upper flight  14  of the conveyor  12 . 
     The view of FIG. 6 is intended to show the manner in which the resilient, elastomeric ribs  58  become compressed or squeezed between the edges defining the slots  42 . The barbs on the serrations are directed such that the sheet  50  can be forced in a downward direction, but effectively precluded from being pushed upward due to possible irregularities in the conveyor belt. Periodically during use, with wearing of the lower edge  54  of the skirt board, it becomes necessary for an operator to hammer down the skirt board to restore a desired degree of contact between the skirt board and the upper flight of the conveyor belt. Ultimately, the worn skirt boards can be removed and replaced with a minimum of down-time. The attachment plate  30  secures the rectangular ribs in a way that prevents the skirt board member  32  from coming loose in the case of belt wander, debris buildup, etc., but can be easily removed for replacement or maintenance by prying loose over end and pulling firmly in a downward and outward direction. 
     In FIG. 7, there is shown a modification of a skirt board mounting plate especially designed to be placed adjacent a transition zone on a conveyor belt flight  12  between a tail pulley  60  to a first of a series of troughing rollers. As is shown at  64 ,  66  and  68 , these slots are not parallel to one another, but instead are spaced further apart at the upper fold line  44  than at the lower edge  36  so that these slots  64 ,  66 ,  68  in the transition zone angle slightly toward one another. In this fashion, the lower edge  36  of the mounting plate effectively bends to conform to the belt  36  at the aforementioned transition zone. A single elongated elastomeric skirt member of the type previously described, and having parallel ribs, can be affixed to the mounting plate  30 &#39;in FIG. 7 even though slots  64 ,  66 ,  68  are slightly angled due to the flexibility of the skirt material which allows it to stretch and compress to fit into the non-parallel slots. 
     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.