Abstract:
This invention relates to an endless fold-over type of conveyor belt for use in conveying relatively-loose bulk material in an enclosed manner to prevent spillage, dusting and contamination of the material and allows the belt to operate at steep angles. The belt comprises essentially a rectangular uniform cross-sectional shape having a substantially greater width than thickness. Two similar arrays of longitudinal grooves are located on the side of the belt opposite to that carrying the load, the grooves being spaced on both sides of the belt medial portion to provide a pair of hinged areas for folding and unfolding the belt. The longitudinal grooves preferably are V-shaped or U-shaped and between one and five grooves may be provided in each array at about one-quarter the belt width from its edges to provide a pair of overlapping edge flaps to cover the medial area when in folded relation.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. Provisional Application Serial No. 60/408,790 filed on Sep. 16, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Technical Field  
           [0003]    This invention generally relates to a flexible endless conveyor belt having a fold-over capability for conveying relatively-loose bulk material from one point to another especially along steep inclines and declines, the belt cover-flaps completely enclosing the load while it is conveyed.  
           [0004]    2. Background Information  
           [0005]    The subject invention which relates to an endless folding belt adapted for use in belt conveyor systems provides a significant improvement in such systems wherein the belt has a substantially longer service life at its hinged areas.  
           [0006]    The belt is adapted for use in conveyor systems to move the folding belt by drive rolls while supported in intermediate areas on idler rolls, the belt having a pair of continuous flexible longitudinal cover or hinge flaps which permit the flaps to be folded and unfolded to facilitate loading and unloading of the belt at several load handling stations or positions. The folding belt is normally folded to enclose bulk materials during their transport from one position to another to eliminate spillage of the load or its contamination during transport and to permit the load to move along steep inclines and declines. The folding belt is capable of carrying significantly greater loads without producing dust-emitting conditions in the vicinity of the belt, the belt having an improved construction in its hinged areas for much longer-service life.  
           [0007]    Prior forms of such folding belts have heretofore utilized single and multiple grooves at their hinged areas on the load-carrying side of the belt. This places a much larger bending moment on the belt in obtaining a hinged effect wherein the belt is essentially folded on itself at the pair of similarly grooved areas. Where the belt is formed from flexible elastomeric material, the interior grooves are compressed in a severe deleterious manner which shortens belt life where the belts are employed to carry significantly greater volumes of bulk material between loading and unloading positions. Belts having such single grooves at the hinged areas on the load-carrying side of the belts are disclosed in U.S. Pat. No. 4,709,806, along with known types of conveyor systems for transport of loose materials in an enclosed manner. While the interiorly grooved hinged areas have been used previously, the amount of undue stress placed on the belt at the hinged areas causes excessive wear and material carried on the belt is often caught in the grooves, prematurely wearing the belt and reducing belt life.  
           [0008]    Prior to the advent of fold-over belts, open belts have been used previously in the art to convey bulk materials in a manner open to the atmosphere. In view of inherent dusting problems, the industry has utilized metal shrouding or other forms of enclosure of the belt to eliminate contamination dusting and to maintain the conveyed material in an essentially clean and uncontaminated condition. The use of shrouding occasionally results in accumulation of dust and in some cases a creation of explosive mixtures which occurrences are particularly dangerous and to be avoided. Prior to the use of folding-belt conveyor systems, such systems were objectionable in allowing spillage of the conveyed material frequently due to belt construction and its mounting for continuous movement. There has been a need in the art for an improved fold-over belt structure having much longer service life which requires lesser maintenance and downtime due to belt failure or weaknesses requiring costly belt replacement.  
           [0009]    U.S. Pat. No. 5,107,983, issued to William H. Tschantz, the inventor of the present invention, which patent is incorporated herein by reference, describes an endless fold-over type of conveyor belt that has a group of closely-spaced longitudinal grooves located on the load-carrying side of the belt. The longitudinal grooved areas are located proximate the edges of the belt and form a hinged area for folding and unfolding the belt. While this belt works fairly well, some problems have been experienced in the conveying of loosely-packed materials such as loose sugar. This type of material tends to become lodged in the grooves and, because of the stickiness of the product, some of the material tends to remain in the grooves after the conveyor has been unloaded. Some of the endless conveyor belts may be of considerable length. Over time the material in the grooves on these long belts may build up to the point that the additional weight on the belt places an unacceptable strain on the motors driving the belt. The material trapped in the grooves may also abrade the belt causing premature wear. Additionally, these belts have been manufactured with the load-carrying side of the belt being made of a softer surface material so that they can be more easily folded at the grooves. When harder load materials, such as coal, are carried on such belts, the hard load material may damage the belt and cause it to delaminate more easily.  
           [0010]    Furthermore, since fold-over belts can go up steep angles due to the pressure of the top flaps trapping material against the bottom carrying side of the belt, it is desirable that the belt have a controlled cross section so that the material will not slide back along the belt in steep angles. Therefore, it is desirable to close the top flaps as much as possible to match the cross sectional area of the belt to the material being carried thereby. When the grooves are formed in the load carrying surface the top flaps are held in compression by overhead rollers. This compression may also cause the belt to delaminate prematurely. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The preferred embodiments of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims.  
         [0012]    [0012]FIG. 1 is a cross-sectional transverse view of the belt showing the multiple grooves at the two similarly hinged areas of the belt;  
         [0013]    [0013]FIG. 2 is a slightly enlarged cross-sectional view of one portion of the belt shown in FIG. 1 showing one hinged area in greater detail;  
         [0014]    [0014]FIG. 2A is an enlarged fragmentary sectional view of the improved fold-over belt;  
         [0015]    [0015]FIG. 3 is a vertical cross-sectional transverse view of the belt in open relation and also showing in a dotted outline, the closed relation of the belt;  
         [0016]    [0016]FIG. 4 is a vertical cross-sectional transverse view of another embodiment of the belt in closed relation in combination with side rolls;  
         [0017]    [0017]FIG. 5 is an enlarged vertical cross-sectional transverse view of one hinged portion of the belt of FIG. 4 showing the multiple grooves in folded relation closing the belt in one form of load carrying relation and engaged with a side roll;  
         [0018]    [0018]FIG. 6 is a top plan view of the belt showing its open and closed positions between loading and unloading positions in a typical conveyor system;  
         [0019]    [0019]FIG. 7 is a cross-sectional view taken along the line  7 - 7  of FIG. 6 showing the central portion of the belt having a deeper medial region for greater load carrying capability with the end flaps in closed relation;  
         [0020]    [0020]FIG. 8 is a second embodiment of the belt in which the grooved areas each have a single groove in the bottom non-load-carrying surface of the belt;  
         [0021]    [0021]FIG. 9 is a third embodiment of the belt in which the grooves are box-shaped;  
         [0022]    [0022]FIG. 10 is a fourth embodiment of the belt in which grooves are formed in both the bottom non-load-carrying surface and the upper load-carrying surface of the belt. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    A typical folding belt conveyor is shown and described in U.S. Pat. No. 4,709,806 entitled “Folding Belt System and Said Belt” issued Dec. 1, 1987, assigned to the Goodyear Tire and Rubber Company. In such a system the continuous endless belt passes over a head-roll or pulley and a tail-roll or pulley, normally called terminals, which are usually located at different elevations. The intermediate area of the belt is supported by a plurality of idler rolls which support the belt in both its open and closed positions. Such system is normally constructed so that three in-line rolls are mounted to cause the belt to form a conventional trough shape in its load carrying arrangement. The rolls may be straight or contoured in such systems which also include tensioning mechanisms to maintain the belt in proper tension to provide for proper driving of the belt in continuous movement for carrying loads such as relatively loose bulk materials without spillage or contamination. Various types of conveyor systems may utilize the fold-over belt of the present invention as set forth hereinbelow.  
         [0024]    Referring to the drawings and specifically FIGS. 1, 2 and  2 A, a belt, generally indicated by the numeral  10 , is preferably formed of three separate layers of a flexible elastomeric material such as rubber. Belt  10  has a top layer  5 , an intermediate layer or carcass  6 , and a bottom layer  7 . In the preferred embodiment, layer  5  will be approximately ⅛ inch thick, intermediate layer  6  will be between {fraction (3/16)} and ⅝ inch thick and bottom layer  7  will be approximately ⅛ inch thick. Furthermore, belt  10  will have a substantially greater width than thickness as shown in FIG. 1 and will have a generally rectangular cross-sectional configuration. Intermediate layer  6  has longitudinal strengthening cords  11  extending lengthwise throughout. Cords  11  are disposed internally of belt  10  in longitudinal spaced-apart parallel relation. Cords  11  provide increased strength to belt  10  for its tensioning without undue elongation or stretching and to assist in retaining it&#39;s rectangular relatively smooth shape. Only a portion of the total number of cords  11  are shown in cross section in FIG. 2.  
         [0025]    As shown in FIGS. 1 and 2, belt  10  may have two similarly shaped arrays  12  and  13  of single or multiple grooves  17  in its lower layer  7 . Areas or arrays  12 ,  13  are preferably spaced equidistant from the edges  29  of the belt  10  and generally one-quarter of the width of belt  10 , to provide fold-over or flap portions  14 ,  15  which extend from the central medial portion  16  of belt  10 . Grooved areas or arrays  12 ,  13  preferably have the same number of similarly-shaped grooves  17  to obtain comparable fold-over effects when end flaps  14 ,  15  are rotated through an angle of about 180° or less. End flaps  14 ,  15  are capable of swingable folding movement over medial portion  16  after a load is disposed on the central belt portion  33 . As shown in FIG. 2, grooved array  12  is shown having four similarly shaped grooves  17  that provide a unitary fold line to distribute inherent stresses over a longer lineal region of the belt width when belt  10  is folded. If multiple grooves  17  are provided, they are preferably spaced an equal distance apart or have a slightly greater spacing in the center portion  18  of belt  10 . When belt  10  is folded and unfolded into and out of load carrying relation, grooves  17  more widely distribute the bending moment stresses. Grooves  17  are preferably similarly shaped having either a V-shape or U-shape and they extend into bottom layer  7  to a position closely adjacent intermediate layer  6 . Grooves  17  do not extend through layer  7  as this could damage the reinforcement provided by layer  6  as should be evident, any number of grooves may be provided without departing from the spirit of the present invention, although 1-5 grooves  17  in each area are preferred.  
         [0026]    The placement of grooves  17  in bottom layer  7  prevents the load material (not shown) from entering and accumulating in the grooves as was the case in the prior art. This in turn prevents a rise in the weight of belt  10  over time from load material accumulating in the grooves. Secondly, having grooves  17  in bottom layer  7  allows flaps  14 ,  15  to be held in tension by rolls  24 , 25 , 26 , 27 . This may reduce the tendency of belt  10  to delaminate. Additionally, bottom layer  7  may be manufactured from a softer material to aid in the folding of the flaps  14 ,  15 . Top layer  5  may be made from a harder, tougher harder material and this may aid in prevent early deterioration of belt  10 . The load materials, such as pieces of coal, do not come into contact with the softer bottom layer  7 , and consequently the potential for damage to the belt is reduced. All these factors assist in increasing the life expectancy of the belt.  
         [0027]    As shown in FIG. 3, belt  10  having longitudinal grooves  17  in paired locations is shown as may be manufactured and employed in use on some types of conveyor systems. End flaps  14 ,  15  are shown in dotted outline as they are moved vertically upwardly over medial portion  16  of belt  10  into the closed load-carrying relation. Numerals  14   a  and  15   a  show the pair of end flaps in closed relation with their edge portions overlapped to completely enclose the load (not shown).  
         [0028]    [0028]FIG. 4 shows in yet another embodiment of belt  10  how end flaps  14   b ,  15   b  may be rotated through an angle of about 180° or less over medial portion  16 . The plurality of V-shaped grooves  17  at the hinged areas  12 ,  13  is shown in greater detail in FIG. 5 wherein swingable rotation of end flaps  14   b ,  15   b  of belt  10  opens grooves  17  distributing the inherent stresses and stretching of belt  10  over a much wider lineal region over a wider hinge line.  
         [0029]    Another important feature of the improved fold-over belt is that the exterior side or edge  30  of belt  10  is large and flat, allowing for easy engagement by side rolls  31 . This feature allows for increased belt control by side rolls  31  and aids in preventing damage to belt  10  especially in horizontal curves. In the prior art, fold-over belts that had rounded sides or edges were prone to damage when engaged by side rolls  31  especially in horizontal curves.  
         [0030]    Referring to FIGS. 6 &amp; 7 of the drawings, on a typical conveyor apparatus (shown partially in the Figure), endless belt  10  is shown in both open and closed relation. Such opening and closing is effected by contoured rolls  21 ,  22 ,  23  located beneath belt  10  and idler rolls  24 , 25 ,  26 ,  27  located over belt  10 . Such view is a schematic view shown in simplified form; the various idler rolls  24 , 25 , 26 ,  27  having various contoured configurations to achieve desirable opening and closing of belt  10 . As shown in FIG. 6, idler rolls  24 ,  25  serve to close belt  10  over the load while idler rolls  26 ,  27  serve to open belt  10  for discharge of the conveyed load. FIG. 7 shows a group of three idler rolls  21 ,  22  and  23  supporting medial region  16  of belt  10  with idler rolls  24 ,  25  closing edge flaps  14 ,  15  over the load retained on belt median portion  16 . Edge flaps  14 ,  15  are preferably overlapped on closing to completely contain the load, although flaps  14 ,  15  may be either totally closed or slightly spaced-apart depending upon the nature of the bulk materials being conveyed. The longitudinal edges  29  of belt  10  may abut each other or may overlap each other when flaps  14 ,  15  are folded inwardly. Grooves  17  lie substantially parallel to each other and to longitudinal edges  29  to facilitate this folding. Additional top roller rolls (not shown) may be employed at other areas of belt  10  during its movement to retain belt  10  in the closed position until it is opened for load discharge at the belt-opening position.  
         [0031]    [0031]FIG. 8 shows a second embodiment of the invention wherein belt  110  is again manufactured with three layers, namely, top load-carrying layer  5 , intermediate reinforcing layer  6  and bottom, non-load-carrying bottom layer  7 . Two similarly shaped areas  112  and  113  are provided, each area having a single groove  117  in bottom layer  7 . Areas  112 ,  113  are preferably spaced equidistant from the edges  29  of belt  110  and generally one-quarter of the width of belt  110 , to provide fold-over or flap portions  14 ,  15  which extend from the central medial portion  16  of belt  110 .  
         [0032]    [0032]FIG. 9 shows a third embodiment of the invention. In this instance, two similarly shaped areas  212  and  213  are provided. Each area  212 ,  213  has box-shaped grooves  217  formed therein. As with the previous embodiment, each groove  217  has a depth less than the thickness of the lower second layer (not shown). Any other suitably shaped groove may be used without departing from the spirit of the present invention.  
         [0033]    [0033]FIG. 10 shows a fourth embodiment of the invention. In this instance two similarly shaped areas  312  and  313  are provided. Each area  312 ,  313  has grooves  317   a  formed in the upper load-carrying layer  5  and grooves  317   b  formed in the bottom non-load-carrying layer  6 . Grooves  317   a ,  317   b  may be of any suitable shape and size without departing from the spirit of the invention.  
         [0034]    An endless fold-over belt  10  which is particularly useful in this invention is a belt formed of usual rubber compositions such as a sulfur carbon black butadiene styrene or butadiene acrylonitrile rubber. This material is preferably cook-cured at an elevated temperature ranging from about 40° C. to 190° C., preferably about 30 to 40 percent of its cure in the flat unfolded open position with the plural longitudinal grooves  17  being molded into belt  10 . In the areas where grooves  17  are formed, end flaps  14 ,  15  are then laid over to bring the edges  29  into the laid-over position. In this position, end flaps  14 ,  15  are usually overlapped so that when in use on the conveyor belt  10  is completely closed. The belt is then finally cured in its folded arrangement with end flaps  14 ,  15  overlying central portion  16 . Grooves  17  may be supported with shims (not shown) during such final curing. Further details of manufacture of the belt and testing thereof are set forth in the aforesaid U.S. Pat. No. 4,709,806 wherein the hinged grooves may be molded into the belt during curing. Grooves may also be cut with knives into belt  10  or grooved into belt  10  with abrading wheels.  
         [0035]    Accordingly, the improved endless conveyor belt of this invention is simplified and provides an effective, safe, inexpensive and efficient device that eliminates many of the difficulties encountered with prior art devices such as belt breakage.  
         [0036]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.  
         [0037]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.