EP0099356A1

EP0099356A1 - Conveyor belt cleaner

Info

Publication number: EP0099356A1
Application number: EP19820900724
Authority: EP
Inventors: Ralph E. Pope; Don J. Cottrell
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-01-18
Filing date: 1982-01-18
Publication date: 1984-02-01
Also published as: WO1983002439A1; AU8200782A

Abstract

Appareil permettant de nettoyer une bande transporteuse et d'en enlever le matériau résiduel restant suite à la décharge du matériau transporté en vrac par la bande transporteuse, lequel appareil comprend un assemblage à rouleau de nettoyage (11) adapté pour engager la bande transporteuse (CB), un dispositif de support (12) monté en rotation aux extrémités opposées de l'assemblage à rouleau de nettoyage (11) pour le mouvement de l'assemblage à rouleau de nettoyage le long d'un chemin rectiligne prédéterminé, un dispositif de commande élastique (40) connecté effectivement à l'assemblage à rouleau de nettoyage pour solliciter sélectivement l'assemblage à rouleau de nettoyage (11) le long du chemin rectiligne prédéterminé en engagement effectif avec la bande transporteuse, et un dispositif d'entraînement (78) faisant tourner l'assemblage à rouleau de nettoyage contre la bande transporteuse pour que l'assemblage à rouleau de nettoyage enlève le matériau résiduel de la bande transporteuse.Apparatus for cleaning a conveyor belt and removing residual material therefrom after discharge of the material transported in bulk by the conveyor belt, which apparatus comprises a cleaning roller assembly (11) adapted to engage the conveyor belt (CB ), a support device (12) rotatably mounted at opposite ends of the cleaning roller assembly (11) for movement of the cleaning roller assembly along a predetermined straight path, a control device elastic (40) effectively connected to the cleaning roller assembly to selectively bias the cleaning roller assembly (11) along the predetermined straight path in effective engagement with the conveyor belt, and a drive device (78) rotating the cleaning roller assembly against the conveyor belt so that the cleaning roller assembly removes residual material from the conveyor belt.

Description

CONVEYOR BELT CLEANER

BACKGROUND OF THE INVENTION This invention relates generally to the cleaning of conveyor belts and more specifically to conveyor belt cleaning apparatus including a grooved resilient cleaning roll, drive means for rotating the roll and support means for resiliently urging the cleaning roll against the con¬ veyor belt.

Conveyor belts for particulate materials, such as coal, chemicals, crushed stone, sand, and the like, typi- cally retain a clinging residue thereon following dis¬ charge of the conveyed material from the belt. Thus, to prevent buildup of this residue on the belt, pulleys, and other mechanisms associated with the conveyor, ^"vari¬ ous belt cleaning devices have been utilized. While the use of scrapers and rotating brushes have been proposed such as those disclosed in U.S. Patent Nos. 766,013 and 1,543,411, these prior art belt clean¬ ing devices have not been adequate to clean the con¬ veyor belts without undue wear and/or damage to the con- veyor belts.

The prior art conveyor belt cleaners that have been the most successful include a counterrotating resilient grooved cleaning roll rotatably mounted between a pair of arms that can be selectively pivotally positioned. U.S. Patent No. 3,161,285 shows such a construction in which the cleaning roll can be inflated to keep it in con¬ tact with the conveyor belt. U.S. Patent No. 3,583,555 shows such a construction in which the pivot arms are urged toward a neutral position by a pair of spring assemblies in which each pivot arm is captured between a pair of springs to allow the pivot arms to pivot with respect to the conveyor belt so that the cleaning roll moves along an arcuate path toward and away from the belt. There are several problems associated with these prior art pivoted belt cleaners. One of these problems

OMPI ' is that the support structure for these cleaners was necessarily large to obtain the necessary lateral sta¬ bility of the cleaning roll, thereby making it difficult to mount the cleaner in the conveyor discharge hopper. Another problem is that the pivot points of the .pivot arms and the stabilizing guides therefor were sensitive to wear and therefore caused the cleaning effectiveness of such cleaners to rapidly deteriorate.^* Yet another problem is that adjustment of the spring pressure on each of the pivot arms was complicated and required multiple manual adjustments, thereby significantly in¬ creasing the maintenance time associated therewith. Still another problem associated with such prior art belt cleaners is that replacement of the resilient cleaning element on the cleaning roll required due to wear was difficult and time consuming.

SUMMARY OF THE INVENTION These and other problems associated with the prior art are overcome by the invention disclosed herein by providing a conveyor belt cleaner which is sufficiently compact to be mounted in the conveyor discharge hopper, which is relatively insensitive to wear even when used in an abrasive environment and in which maintenance adjustments and replacement of the cleaning element are greatly simplified. The rotating cleaning roll is resiliently urged toward the conveyor belt along a recti¬ linear rather than an arcuate path so that the cleaning roll does not shift along the belt as it moves to accom¬ modate belt irregularities. Adjustment of the spring pressure on opposite ends of the cleaning roll is ef- fected through a single manual adjustment. Further, the cleaning element is made in standard length segments so - that the projections thereon automatically align as the desired number of segments are assembled on the cleaning roll to facilitate manufacture of cleaning rolls for different width conveyor belts and the replacement thereof due to wear.

Accordingly, the invention provides conveyor clean¬ ing apparatus for wiping clinging material from a moving conveyor belt following discharge of conveyed particu- late material into a discharge hopper as the belt is redirected over a head pulley to return for additional material comprising a cleaning roll assembly rotatably -mounted in a pair of support assemblies to urge the cleaning roll assembly against the conveyor belt. A drive assembly is mounted on one of the support assem¬ blies for rotating the cleaning roll assembly against the belt surface. Each of the support assemblies in¬ cludes a base plate which movably mounts a bearing plate between guide channels for reciprocal movement along a rectilinear path. A control assembly resiliently posi¬ tions each bearing plate. The support assemblies are

OMPI positioned cm opposite sides of the conveyor and the cleaning roll assembly is rotatably journalled therebe¬ tween in bearings carried on the movable bearing plates. The control assembly serves to both urge the cleaning roll assembly against the belt surface to clean it and to absorb the shock when the cleaning roll assembly re¬ turns to its nominal position after deflection.

The construction of the support assemblies is such that the movable plates can be loosely fitted in the guide channels without affecting the operation thereof. Because the support assemblies are direct acting rather than pivoted, the amplitude of the reciprocatory motion of the movable bearing plates is reduced to a minimum during operation. As a result, frictional wear in the support assemblies is minimized even when the invention is used in abrasive environments such as those typicall found with conveyor systems with which the invention is to be used.

These and other features and advantages of the in- vention disclosed herein will become more apparent upon consideration of the following description and accom¬ panying drawing wherein like characters of reference designate corresponding parts throughout the several views and in which: BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a view illustrating the invention in¬ stalled on a conveyor system;

Fig. 2 is an enlarged elevational view of the non- drive support assembly; Fig. 3 is a cross-sectional view taken generally along line 3-3 in Fig. 2;

Fig. 4 is an enlarged cross-sectional view taken generally along line 4-4 in Fig. 3;

Fig. 5 is an enlarged cross-sectional view taken generally along line 5-5 in Fig. 3;

OMPI ^y/ m Fig. 6 -±s an enlarged elevational view of one of the support assemblies of the invention shown partly in cross-section-; and

Fig. 7 is a cross-sectional view taken generally along line ^"7-7 in Fig. 6.

These figures and the following detailed description disclose specific embodiments of the invention; however, it is to be understood that the inventive concepts may be embodied in other forms. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The cleaning assembly 10 of the invention is shown installed in a typical operating configuration in Fig. 1 adjacent the upper discharge end DE of a conventional material transporting conveyor system CS. The conveyor system CS is only partly shown in Fig. 1 and includes a flexible conveyor belt CB trained over appropriate pulleys to create an upwardly inclined carry flight CF and a downwardly inclined return flight RF. The dis¬ charge end DE of the conveyor system is typically located in a discharge hopper DH partly seen in Fig. 1. The uppermost belt pulley is typically called the head pulley and is designated HP in Fig. 1. The head pulley is usually located in the discharge hopper DH as seen in Fig. 1 and is journalled about pulley axis A in bearings B usually mounted on the hopper side walls SW„. The con¬ veyed particulate material is gravitationally discharged over the discharge end of the conveyor as shown by arrow D in Fig. 1 and falls into the hopper DH.

The cleaning assembly 10 serves to remove any resi- dual clinging material carried around the head pulley past the discharge point from the conveyor belt. While the cleaning assembly 10 is illustrated located adjacent the head pulley so that the residual material removed by the cleaning assembly will fall into the hopper DH, it may likewise be located at any convenient position along the return flight of the conveyor belt without departing from the scope of the invention.

The cleaning assembly 10 includes a cleaning roll assembly 11 rotatably journalled in a pair of support as- semblies 12. For the particular installation illustrated in the drawings, the support assemblies 12 are mounted on the hopper side walls SW_H so that the roll assembly 11 is rotatably mounted about roll axis A_R, usually parallel to the head uplley axis A . The cleaning roll assembly 11 contacts the material carrying surface of the conveyor belt CB and is rotated thereagainst with a wiping action to wipe the clinging material from that surface. Typi¬ cally, the cleaning roll assembly is^" rotated so that it moves countercurrent to the belt surface movement at the point of contact. It is to likewise be understood that the roll assembly may be rotated in the same direction as the belt movement in certain applications without de¬ parting from the scope of the invention. The support assemblies resiliently mount the cleaning roll assembly 11 for movement toward and away from the conveyor belt so that the cleaning roll assembly can be deflected to permit joints, splices and other belt irregularities to pass the cleaning roll assembly.

The cleaning roll assembly 11 best seen in Figs. 3 and 4 includes a cylindrical mounting arbor 14 equipped with mounting shafts 15 on opposite ends thereof co- axially extending with respect to arbor 14. The arbor 14 is equipped with longitudinally extending drive keys 16 projecting outwardly from the outer surface of the arbor. Resilient annular roll segments 18 of outside diameter D_R are fitted onto the outer' surface of arbor 14 to complete the roll assembly 11. The roll segments 18 are provided with internally opening keyways 19 adapted to fit over and drivingly engage the drive key so that the roll segments 18 are rotated ith arbor 14.

OMPI The outer peripheral surface of the roll segments 18 are provided with spaced apart helically extending resilient ribs 20 that contact the belt surface to clean it. The recesses 21 between ribs 20 are constructed and arranged to permit the removed particulate material to fall off of the cleaning roll assembly so that it is self-cleaning. The helix angle of the ribs 20 is selected so^' that the ribs 20 at the opposite ends of each segment have the same orientation with respect to the keyways 19 so that the ends of the ribs 20 on each segment 18 automatically^' align with the ends of the ribs 20 on an adjacent segment 18 as seen in Fig. 3. This permits the segments 18 to be assembled on arbor 14 so that the ribs 20 form compo¬ site continuous ribs along the length of roll assembly 11 or to form a herringbone pattern as desired. The number of roll segments 18 may be varied as desired so that the overall working length of the roll assembly 11 . corresponds to the width of the conveyor belt CB to be cleaned. A standard segment length of about six inches has been found convenient since most conveyor belt widths are in six-inch increments. Because the segments 18 are relatively short, the original mounting or replacement thereof on arbor 14 is facilitated since the fcrce required to mount or remove the segment is much less than that re- quired for an element equal to the length of the arbor 14. Further, different length elements do not have to be inventoried to accommodate cleaning roll assemblies for different width conveyor belts.

The angle of opposite sides of each of the ribs 20 is the same so that the cleaning e fectiveness of the segments 18 is the same regardless of direction of rota¬ tion. This facilitates assembly of the segments 18 on arbor 14 since the workman does not have to pay particu¬ lar attention to the orientation of the segments 18 with respect to roll rotation. Further, the material from which the segments 18 are made and the hardness thereof significantly affects the performance and wearability thereof. It has been found that a urethane/nylon mate¬ rial mixture which has a durometer value of 88-105 pro- duces the best results with a durometer value of about 98 preferred. This construction increases wearability of the cleaning element at least 3-4 times that of the prior art.

The support assemblies 12 are mounted on the outside of the hopper side walls SW„ over appropriately sized cutouts C with the mounting shafts 15 on roll assembly 11 extending through these cutouts. Each of the support assemblies 12 as best seen in Figs. 2-4 includes a base plate 25 fixedly yet removably mounted on the outside of side wall S _H about the cutout C by conventional means such as by bolts 26 shown in the drawings. The base plate 25 is likewise provided with an opening 28 there¬ through as best seen in Figs. 3 and 4 so that opening 28 is in registration with the cutout C in the side wall S^u_* The cutouts C are large enough for the roll as¬ sembly 11 to pass therethrough as will become more appa¬ rent. The opening 28 in base plate 25 has a width W greater than the diameter of the mounting shaft 15 and a height H sufficient for the mounting shaft IS and roll assembly 11 to move through the full range of adjustment without striking base plate 25 as will become more appa¬ rent.

Opposed parallel guides 29 seen in Figs. 2 and 4 are provided on opposite sides of the opening 28 which serve to movably mount a bearing plate 30 therebetween over opening 28 so that the bearing plate is movable along a path P_M seen in Figs. 1 and 2 oriented generally normal to the surface of the conveyor belt CB at the point of contact with roll assembly 11 as will become more appa- rent. An inwardly opening plate receiving space 31 is

CMPI ™° defined between each guide 29 and the outside surface of the base plate 25 with a thickness t perpendicular to plate 25 greater than the thickness of the bearing plate 30 and a depth d . The guides 29 are positioned equidistant on opposite sides of the centerline of the base plate 25 so that the distance d, between the bottoms of spaces 31 in guides 29 is greater than the overall width of the bearing plate 30 so that the bearing plate

30 is loosely received in spaces 31. A graphite rub strip 27 is mounted in the bottom of each of the spaces

31 to provide a bearing surface for opposite edges of the bearing plate 30 to slide against. The bearing plate 30 is provided with a centrally located shaft opening around which a bearing 32 is mounted on the outside of plate 30 with conventional means such as bolts 34 as seen in Figs. 2-4.

The shafts 15 on roll assembly 11 are slidably re¬ ceived through the inner races of bearings 32 on the opposed support assemblies 12 so that the roll assembly 11 is rotatably journalled by bearings 32 about axis A_R. Appropriate set screws 33 are provided to lock shafts 15 to bearings 32. This serves to facilitate mounting the cleaning assembly and replacement of the roll segments 18 as will become more apparent. Reciprocal motion of the bearing plates 30 and thus roll assembly 11 along the path P„ is controlled by a control assembly 40 on each support assembly 12 in combi¬ nation with the conveyor belt CB. The control assembly 40 serves to apply an adjustable loading force urging the cleaning roll assembly 11 up against the conveyor belt CB to cause the roll assembly 11 to remove any residual clinging material therefrom while at the same time per¬ mitting the cleaning roll assembly to be resiliently dis¬ placed downwardly to accommodate any irregularities in the belt CB such as splices and the like. The control assembly 40 best seen in Figs. 6 and 7 is illustrated as a compression spring assembly. An up¬ per base tab 41 is affixed to the base plate 25 and pro¬ jects outwardly therefrom over the bearing plate 30. The base tab 41 lies in registration with the path P_M through the roll axis A_R and defines a hole 42 there¬ through normal to the roll axis A_R. A positioner 44 is adjustably mounted in the hole 42 in tab 41. The posi¬ tioner 44 includes a mounting bolt 45 whose threaded portion is slidably received through hole 42. A lower adjustment nut 46 is threadedly received on bolt 45 below tab 41 and an upper adjustment nut 48 is threadedly received on bolt 45 above tab 41 so that, as the nuts 46 and 48 are tightened against the opposite sides of tab 41, the bolt 45 can be selectively axially fixed with respect to tab 41. The bolt 45 is provided with a head 49 at its lower end below the tab 41 to which is affixed an elongate base member 50. The base member 50 is ori¬ ented perpendicular to the axis of bolt 45 and the path P_M but parallel to the plates 25 and 30 and spaced out¬ board thereof. Thus, the distance d₂ between the tab 41 and the base member 50 can be selectively adjusted by manipulating the nuts 46 and 48.

A bracket 51 is affixed to the upper edge of the bearing plate 50 so that the bracket 51 projects above the plate 30. Bracket 51 is centered across plate 30 and also centered on path P,,. The upper portion of bracket 51 is provided with a pair of spring tabs 52 which project out over opposite ends of the base member 50. The spring tabs 52 are located equidistant on oppo¬ site sides of the p ^rath PM,_τ and the axis of bolt 45 and oriented parallel to the base member 50. A guide pin 54 is affixed to each^' of the spring tabs 52 and extends therebelow. The guide pins 54 are likewise located equidistant on opposite sides of the path P,, and bolt 45 II

and are oriented so that their axes A₂ are parallel to the axis A, of bolt 45. The guide pins 54 slidably extend through holes 55 in opposite ends of the base member 50. A retaining washer 56 is affixed to the lower end of each of the guide pins 54 below the base member 50 to keep the base member 50 slidably mounted on pins 54.

A compression type coil spring 58 is received around each of the guide pins 54 between the spring tab 52 and the base member 50 to urge them away from each other. The length of the springs 58 and the position of the washers -56 on the guide pins 54 is selected to give the desired range of movement between tabs 52 and base member 50 as well as the desired spring preloading force to be maintained when the base member 50 is supported on the washers 56 as will become more apparent.

It will now be^' appreciated that the bearing plate 30 is resiliently supported on the base member 50 through the springs 58. The bearing plate 30 can be deflected downwardly with respect to the base plate 25 by com¬ pressing springs 58 to force spring tabs 52 toward base member 50. The entire control assembly 40 and bearing plate 30 can be shifted with respect to base plate 25 by manipulating the nuts 46 and 48 without affecting the range of operation of control assembly 40.

With the roll assembly 11 mounted between the sup¬ port assemblies 12 as seen in Fig. 3, the nuts 46 and 48 in the control assemblies 40 are adjusted to move the ribs 20 into contact with belt CB. Further movement of the base members 50 toward belt CB compresses springs 58 to apply the necessary loading force to the belt CB to affect cleaning of the clinging material therefrom. This moves the base member 50 off of the washers 56 as seen in Figs. 6 and 7 so that the bearing plates 30 and roll as- sembly 11 are free to float up and down with conveyor belt CB. Thus, control assemblies 40 serve both to apply the primary loading force between the belt CB and roll assembly 11 as well as a vibration damper as the belt is being cleaned. While compression springs are illustrated as being used to provide the adjustable loading forces for the cleaning roll assembly 11, it is appreciated that other mechanisms may be used without departing from the scope of the invention. For instance, pneumatic spring assem- blies may be used in lieu of the mechanical springs shown or selectively pressurized pneumatic cylinders may likewise be used.

A drive assembly 75 is mounted on the outside of one of the movable bearing plates 30 for rotatably driving the cleaning roll assembly 11 and is best seen in Figs. 1 and 3. The drive assembly 75 includes a generally U- shaped bridge 76 with the projecting ends of its legs attached to the movable plate 30 on opposite sides of the bearing 32. This forms an appropriate access opening over the end of the itiLl shaft 15 projecting through bearing 32 as will become more apparent. A drive motor 78 is mounted on the central web portion of bridge 76 in axial alignment with the roll shaft 15 and the drive shaft 79 from motor 78 projects through an appropriate opening in the bridge 76 into the access space between bridge 76 and plate 30. A shaft coupling 80 drivingly connects the aligned ends of the motor drive shaft 79 and the roll support shaft 15 so that rotation of motor 78 drivingly rotates the cleaning roll assembly 11 against conveyor belt CB to clean it. The coupling 80 also serves to axially fix the roll shaft 15 with respect to the motor shaft 79. Since the motor 78 and its shaft 79 are fixed with respect to the bearing plate 30, the mounting arbor 14 is axially fixed with respect to the bearing plate 30 even though the roll shafts 15 are slidably mounted in bearings 32. This facilitates replacement of the worn roll segments 18 as will become more apparent.

For effective cleaning action, the drive motor 78 usually rotates the cleaning roll assembly 11 at a speed such that the linear speed of that portion of the ribs 20 on the roll segments 18 is considerably greater than the linear speed of conveyor belt CB. One typical rotational speed is about 1750 rpm. The effective linear speed differences between ribs^* 20 on segments 18 and belt CB is enhanced when the roll assembly 11 is rotated countercurrent to. the movement of belt CB.

INSTALLATION AND OPERATION While the invention may be installed at any conve¬ nient location on the return flight of the conveyor belt, it is illustrated as being installed adjacent the head pulley HP within the discharge hopper DH. The location at which the cleaning assembly 10 is to be located is first selected as will become more apparent. Once this location is selected, the cutouts Co are formed in the hopper side walls SWr_Ul adjacent the conveyor belt CB as best seen in Figs. 1 and 3. The cutouts C are suffi¬ ciently large for the cleaning roll assembly 11 with the roll segments 18 thereon to be passed through the cutouts C into the inside of the discharge hopper DH. After the cleaning roll assembly 11 is positioned within the hopper DH, the support assemblies 12 are fitted onto the ends of the mounting shafts 15 projecting from opposite ends of the cleaning roll assembly 11. It will be noted that the mounting shafts 15 are simply slipped through the bearings 32. At this time, the control assemblies 40 are adjusted to their lowermost position and the entire cleaning as¬ sembly 10 is lifted with an appropriate lift device so that the ribs 20 on the roll segments 18 are substantially parallel with the surface of the conveyor belt CB and closely adjacent thereto. With the cleaning assembly 10 held in this position, the base plates 25 are attached to the side walls SW„ of the hopper DH to fixedly mount the support assemblies 12 onto the hopper side walls. After this is done, the cleaning roll assembly 11 is appro¬ priately shifted axially until it is centered under the conveyor belt CB and the coupling 80 attached to the mounting shaft 15 projecting into the access space under the bridge 76. This serves to axially fix the cleaning roll assembly 11 with respect to the support assembly 12 mounting the drive assembly 75. After this is done, the control assembly 40 is adjusted to urge the cleaning roll

OMPI assembly 11 against the return flight of the conveyor belt CB. Thus, as the motor 78 rotates the cleaning roll assembly 11, it will be seen that the ribs 20 wipe the clinging material from the return flight of the conveyor belt CB.

Typically, the control assemblies 40 are adjusted so that appropriate loading is provided between the cleaning roll assembly 11 and the conveyor belt CB while at the same time allowing the control assemblies 40 to partially absorb the shock as the cleaning roll assembly 11 is returned against the conveyor belt CB after the cleaning roll assembly 11 has been deflected by a splice or joint in the conveyor belt CB passing the cleaning roll assembly 11. It will be appreciated that, because the movable bearing plates 30 are loosely mounted in the guide chan¬ nels 29, abrasive particulate material falling in be¬ tween the moving parts on the support assemblies 12 can pass therethrough so that the support assemblies 11 are self-cleaning. This is very important when the cleaning assembly 10 is used in abrasive environments such as those typically associated with the conveyor systems of the types discussed. • Further, it will be appreciated that, since the control assemblies 40 are located above roll assembly 11, they are effectively shielded from the abrasive environments.

When the cleaning assembly 10 is in operation, it will be appreciated that the major portion of the load is carried by the springs 58 of the control assemblies 40. The control assemblies 40 further serve as one of the pri¬ mary orientation mechanisms for the movable bearable plates 30 so that the frictional contact between the bearing plates 30 and the guides 29 is minimized to thus minimize the wear associated therewith. As the ribs 20 on roll segments 18 wear, the control^' assemblies 40 are adjusted to maintain cleaning effi¬ ciency. This adjustment is normally required only after several months of operation and is greatly simplified since only a single adjustment need be made in each sup- port assembly 12. When the ribs 20 eventually wear out, the segments 18 may be replaced simply by disconnecting the bolts 26 of the non-drive support assembly 12 and that support assembly 12 slipped off the end of the mounting shaft 15 on the cleaning roll assembly 11. The cleaning roll assembly 11 is held in place by the drive support assembly 12. Because the cleaning roll assembly 11 is smaller in diameter than the cutout C in the hopper side walls SW„, the segments 18 may be slipped off the ar¬ bor 14 and new segments 18 slipped onto the arbor 14. After the non-drive support assembly 12 has been replaced, the operation of the cleaning assembly 10 can be resumed. ^"It will be appreciated that the path of movement P,. of the cleaning roll assembly 11 may be oriented as de¬ sired while the supporting assemblies 12 are being at- tached to the side walls S _R. Typically, the path of movement P„ is oriented normal to the return flight RF of conveyor belt CB and is shifted downcourse of the depar¬ ture point of the return flight of the conveyor belt CB from the head pulley HP. This downcourse distance is conveniently defined by a lag angle A_τ defined between a reference plane RP_D extending from the axis A of the head pulley HP to the point of departure of the return flight RF of the conveyor belt CB from the head pulley HP and the reference plane RP_R extending between the axes Ap and A_R of the head pulley HP and the cleaning roll assembly 11 respectively. The lag angle A_γ is selected so that the return flight RF of the conveyor belt CB can be deflected a limited amount without causing deflection of the cleaning roll assembly 11. The permissible amount of deflection of the return flight RF of belt CB together with the loading exerted on the cleaning roll assembly 11 by the control assemblies 40 causes minor irregularities in the conveyor belt CB to deflect the return flight RF of the conveyor belt rather than de- fleeting the cleaning roll assembly 11 while at the same time, larger irregularities in the conveyor belt CB such as joints and splices will cause the cleaning roll as¬ sembly 11 to be deflected against the action of the con¬ trol assemblies 40 so that these larger irregularities can pass by the cleaning roll assembly 11 without damage to the cleaning roll assembly or the conveyor belt. Thus, there is a threshold disturbance level below which the cleaning roll assembly 11 remains substantially in¬ active whereas disturbances greater than this threshold level cause deflection in ^"both the conveyor belt CB for a limited amount and the deflection of the cleaning roll assembly 11 downwardly. Typically, this threshold dis¬ turbance level is set by locating the cleaning roll as¬ sembly 11 sufficiently close to the head pulley HP so that the conveyor belt CB will engage the head pulley HP after the permissible amount of deflection has occurred. This configuration is especially suited for the usual situation where the- head pulley diameter is substantially greater than the cleaning roll diameter. It has been found that a lag angle A. of about 2-5 degrees performs satisfactorily. It is also to be understood that a simi¬ lar operation can be achieved at other locations along the return flight RF of the conveyor belt CB by adjusting the control assemblies 40 to permit deflection of the cleaning roll assembly 11 upon the tautness of the return flight RF of the conveyor belt CB reaching a selected value corresponding to a threshold disturbance level as discussed above.

Claims

WHAT IS CLAIMED AS INVENTION IS:

1. Apparatus for cleaning residual material from the return flight of a conveyor belt following discharge of the bulk of the conveyed material from the conveyor belt comprising: a cleaning roll assembly adapted to engage the conveyor belt to clean the residual material therefrom; support means rotatably mounting opposite ends of said cleaning roll assembly and operatively associa- ting said cleaning roll assembly with the return flight of the conveyor belt; and drive means operatively associated with said cleaning roll assembly and said support means for se¬ lectively rotating said cleaning roll assembly with respect to the conveyor belt to cause said cleaning roll assembly to remove the residual material from the conveyor belt; said support means including guide means ope¬ ratively connected to said cleaning roll assembly for movement of said cleaning roll assembly along a prescribed rectilinear path and resilient control means operatively connected to said cleaning roll assembly for selectively urging said cleaning roll assembly along said prescribed rectilinear path into operative engagement with the con- veyor belt so that said cleaning roll assembly removes the residual material from the conveyor Belt yet said cleaning roll assembly can be deflected along said pre- scribed rectilinear path against the action of said control means.

2. The apparatus of Claim 1 wherein said support means includes a pair of support assemblies and wherein each of said support assemblies includes a base plate defining an opening therethrough fixedly located at a prescribed location adjacent the return flight of the conveyor belt, a pair of guides fixedly mounted on said base plate, on opposite sides of said opening and forming said guide means, a bearing plate movably mounted between said guides and said base plate over said opening for movement of said bearing plate along said prescribed rectilinear path wherein the fit between said bearing plate and said base plate and said guides is sufficiently loose to permit material removed from the conveyor belt to pass therebetween to reduce the wear thereon; and bearing means mounted on said bearing plate to rotatably support one end of said cleaning roll assembly.

3. The apparatus of Claim 2 wherein said resilient control means includes a pair of control assemblies,^' one being associated with each of said support assemblies, each of said control assemblies including a base member, spring means resiliently connecting said base member and said bearing plate; and adjustment means adjustably con¬ necting said base member to said base plate so that said base member can be moved with respect to said base plate without affecting the resiliency range of said spring means and to selectively vary the force exerted on the conveyor belt by said cleaning roll assembly through said ^' spring means.

4. The apparatus of Claim 3 wherein each of said control assemblies further includes a pair of spaced apart guide pins slidably interconnecting said base mem¬ ber and said bearing plate to limit the relative movement between said base member and said bearing plate.

_ O PI

5. The apparatus of Claim 4 wherein said spring means in each of said control assemblies further includes a pair of coil springs, one of said coil springs being positioned around each of said guide pins and located equidistant from said adjustment means.

6. The apparatus of Claim 1 wherein said cleaning roll assembly includes a support arbor; drive key means on said support arbor; and a plurality of cleaning roll segments, each defining a central passage therethrough slidably receiving said support arbor and a keyway therein slidably receiving said drive key means to drivingly interconnect said support arbor and said cleaning roll segment, each of said cleaning roll segments defining a plurality of helically extending ribs thereon oriented so that said ribs have the same position relative to said keyway at the opposite ends of said roll segment so that said ribs on each of said roll segments align with said ribs on adjacent roll segments when said plurality of roll segments are mounted on said support arbor.

7. The apparatus of Claim 1 wherein said cleaning roll assembly includes an elastomeric cleaning element defining a plurality of helically extending ribs thereon to engage the conveyor belt and having a durometer value of 88-105.

O PI

8. The apparatus of Claim 2 wherein said resilient control means includes a pair of control assemblies, one being associated with each of said support assemblies, each of said control assemblies including spring means resiliently connecting said base plate and said bearing plate for resiliently urging said bearing plate along said rectilinear path with respect to said base plate in a first direction, guide means for limiting the movement of said bearing plate with respect to said base plate in said first direction along said rectilinear path, and adjustment means for selectively shifting said spring means and said guide means with respect to said base plate along said rectilinear path.

9. The apparatus of Claim 8 wherein said cleaning roll assembly includes a support arbor; drive key means on said support arbor; and a plurality of cleaning roll segments, each defining a central passage therethrough slidably receiving said, support arbor and a keyway therein slidably receiving said drive key means to drivingly interconnect said support arbor and said cleaning roll segment, each of said cleaning roll segments defining a plurality of helically extending ribs thereon oriented so that said ribs have the same position relative to said keyway at the opposite ends of said roll segment so that said ribs on each of said roll segments align with said ribs on adjacent roll segments when said plurality of roll segments are mounted on said support arboτ.

O PI

10. The apparatus of Claim 5 wherein said cleaning roll assembly includes a support arbor; drive key means on said support arbor; and a plurality of cleaning roll segments, each defining a central passage therethrough slidably receiving said support arbor and a keyway therein slidably receiving said drive key means to drivingly interconnect said support arbor and said cleaning roll segment, each of said cleaning roll segments defining a plurality of helically extending ribs thereon oriented so that said ribs have the same position relative to said keyway at the opposite ends of said roll segment so that said ribs on each of said roll segments align with said ribs on adjacent roll segments when said plurality of roll segments are mounted on said support arbor.

" τj E T-