Drag conveyor system for particulate material

Abstract

A drag conveyor consists of a uniquely-configured trough and correspondingly-shaped outer edges of chain-driven paddles which enable the trough construction to provide physical support for a return of the chain. The cross-sectional shape of the trough further restricts the paddles from tending toward lifting above the trough bottom and climbing or twisting as they carry material toward the outlet end of the conveyor. The paddle shape results in a self-cleaning conveyor, even enabling handling of materials heretofore not feasible with conventional U-shaped trough conveyors. Elimination of obstructing idler sprockets and cross shafts of the prior art enables a productivity increase of as much as 15% for the same designated size of conveyor.

Having described my invention, I claim:  
     
       1. In a drag conveyor system for moving particulate material from an inlet an one location to an outlet at a remote location; said conveyor comprising an elongated continuous link chain movable in a vertical plane about a drive sprocket at one end adjacent one of said locations and a tail sprocket adjacent the other of said locations, motor means for driving said drive sprocket, a trough having a bottom, opposed sides, an open top and a cover for said open top, said trough encompassing said chain throughout its length, a plurality of material-carrying paddles spaced longitudinally about said chain and extending radially outward therefrom; said paddles having their outermost edges corresponding in shaped and size to the bottom of said trough to drag material introduced into said trough at said inlet toward and to said outlet, the improvement comprising: 
       said trough having:  
       a). a cross-sectional configuration including a lower material-carrying section preferably encompassing a lower run of said chain and portions of inner edges of said paddles along said lower run, said inner edges and lower section restraining said paddles and chain against rotational twisting movement relative to said trough;  
       b). an upper return run section immediately above said lower section and encompassing the upper run of said continuous chain, said upper section having portions thereof directed inwardly of the sides of said trough for edgewise supporting of the inner edges of the paddles in their passage through said return run section from said outlet to said inlet; and  
       said paddles being relatively flat in a direction normal to said chain and having peripheral edges corresponding to the configuration of said lower section, whereby outer edges of material-carrying paddles moving along said lower run section side frictionally against the bottom and adjacent side edges of said trough when carrying material toward side outlet and wherein inner edges of said paddles moving along said return run section ride frictionally and are solely supported by the inwardly-directed sides of said upper section to support the chain in said return run section.  
     
     
       2. The invention according to claim  1  wherein said inwardly-directed sides also restrain said paddles and chain against twisting when situated within said lower section. 
     
     
       3. The invention according to claim  2  wherein said inwardly-directed sides form sidewise-lying V's with their apexes facing each other, said apexes lying on an imaginary parting line between mirror-images upper and lower sections. 
     
     
       4. The invention according to claim  3  wherein that portion of the inwardly-directed sides above the parting line provides support for the inner edges of the paddles in said return run section and that portion of the sides below the parting line are closely spaced relative to the inner edges of the paddles when in said lower section, whereby to restrain the chain against any tendency to twist. 
     
     
       5. The invention according to claim  1  wherein said paddles and each of said lower and upper sections is essentially the cross-sectional shape of a vertically-compressed hexagon. 
     
     
       6. The invention according to claim  5  wherein the bottom of said trough if flat and has outwardly and upwardly diverging sides terminating at a point and then converging upwardly and inwardly to form five sides of said hexagon shape, and wherein said upper section comprises outwardly and upwardly diverging sides forming the portion of said trough which supports the outer edges of said paddles in said return run section, the diverging sides of said upper section being angled to enable particulate material to descend by gravity to the bottom of the trough upon completion of a run of said material. 
     
     
       7. The invention according to claim  6  wherein the trough terminates at the upper edges of the sides of said upper section, and wherein the remaining three sides of the hexagon shape of said upper section are formed by a removable cover having a relatively flat top and outwardly and downwardly-diverging sides corresponding generally in shape and size to the bottom three sides of said trough. 
     
     
       8. The invention according to claim  1  wherein said trough bottom is V-shaped. 
     
     
       9. The invention according to claim  1  wherein said trough bottom is circular. 
     
     
       10. The invention according to claim  1  wherein said trough bottom is oval. 
     
     
       11. The invention according to claim  1  wherein the sides of said trough intermediate said upper and lower sections are symmetrical. 
     
     
       12. The invention according to claim  1  wherein the sides of said trough intermediate said upper and lower sections are asymmetrical. 
     
     
       13. In a drag conveyor system for moving particulate material from an inlet at one location to an outlet at a remote location: said conveyor system comprising an elongated endless link chain having upper and lower runs movable in a vertical plane about a drive sprocket at one end of said locations and a tail sprocket adjacent the other of said locations, motor means for driving said drive sprocket, an elongated trough having a bottom, opposed sides, an open top and a cover for said open top, said trough encompassing said chain throughout its length, a plurality of material-carrying paddles spaced longitudinally about said chain and extending laterally and radially outward therefrom; said paddles having their radially outer edges corresponding in shape and size to the bottom of said trough to drag material introduced into said trough at said inlet toward and to said outlet, said trough having: 
       
         a lower material-carrying section encompassing the lower run of said chain and paddles moving along said lower run; an upper return run section immediately above said lower section and encompassing the upper run of said chain and paddles, said upper section having elongated bearing surface portions thereof directed downwardly and inwardly from opposite sides of said trough for edgewise frictional supporting of inner laterally outward edges of the paddles in their passage through said return run section from said outlet to said inlet; and  
       
       
         said paddles being relatively flat and having a thickness in a direction normal to said chain and further having outer edges which ride frictionally against the trough bottom when carrying material toward said outlet in said lower material-carrying section, and said paddles further having opposed laterally outward inner edges inclined at the same angle as said bearing surface portions for riding frictionally on and providing the sole support for the chain and paddles on the inwardly-directed bearing surface portions of said upper section while travelling through said upper return run section, said angled inner edges of the paddles providing a substantial bearing surface of said paddles against the bearing surface portions. 
       
     
     
       14. The invention according to claim  13  wherein the inner surfaces of the opposed sides adjacent the trough bottom slope downwardly at an angle toward the trough bottom and tend to feed all material toward the bottom by gravity, and wherein said paddle outer edges correspond to said bottom and the adjacent inner sloping sides of said opposed surfaces, thereby enabling self-cleaning of the trough bottom at the end of a run. 
     
     
       15. The invention according to claim  13  wherein the trough bottom is flat and lies in a horizontal plane, wherein a gated outlet is provided intermediate said inlet and said outlet to enable material being conveyed to be discharged from the trough in advance of said outlet, and wherein a gate comprising a flat plate having an upper surface coplanar with the flat bottom of the conveyor system is movable at a right angle to said conveyor system to enable opening and closing of said gated outlet. 
     
     
       16. The invention according to claim  15  wherein said opposed side inner surfaces are flat and lie in intersecting planes each of which is inclined downwardly toward a juncture at said flat bottom. 
     
     
       17. The invention according to claim  13  wherein each said paddle is in the range of approximately {fraction ( 5 / 8 )}ths of an inch in thickness, and wherein the inner edge of each paddle intermediate the laterally outward portions thereof extends horizontally and is beveled relative to the vertical plane at an angle to the horizontal in order to inhibit particulate material from collecting atop said intermediate inner edge while the paddles are passing through said lower material-carrying section. 
     
     
       18. The invention according to claim  13  wherein each of said paddles and each of said upper and lower sections are essentially the cross-sectional shape of a vertically-compressed hexagon having a flat top, a flat bottom and diagonal sides interconnecting the flat top and flat bottom, with the flat bottom and laterally outer edges of said paddles frictionally engaging the trough bottom and adjacent portions of said opposed side walls of said trough in said lower section and the diagonal laterally outward inner edges of said paddles frictionally engaging said bearing surface portions in said upper return run section. 
     
     
       19. The invention according to claim  18  wherein said lower material-carrying section closely corresponds in size and shape to said vertically-compressed hexagonal paddles, whereby to restrain said paddles and chain against rotational twisting movement relative to said trough while conveying material through said lower section. 
     
     
       20. The invention according to claim  1  wherein the trough bottom is flat and lies in a horizontal plane, wherein a gated outlet is provided intermediate said inlet and said outlet to enable material being conveyed to be discharged from the trough in advance of said outlet, and wherein a gate comprising a flat plate having an upper surface coplanar with the flat bottom of the conveyor system is movable at a right angle to said conveyor system to enable opening and closing of said gated outlet. 
     
     
       21. The invention according to claim  20  wherein each said paddle is approximately {fraction ( 5 / 8 )}ths of an inch in thickness, and wherein the inner edge of each paddle intermediate the laterally outward portions thereof extends horizontally and is beveled relative to the vertical plane at an angle to the horizontal in order to inhibit particulate material from collecting atop said intermediate inner edge while the paddles are passing through said lower material-carrying section.