Abstract:
A method comprises a step of accessing a conveyor belt system that has a belt, a return roller, and a return roller support assembly. The return roller is supported by the return roller support assembly. The return roller is engaged with the belt from beneath the return run. The method also comprises operating the return roller support assembly in a manner causing the return roller to lower relative to the belt to a position where the return roller is no longer engaged with the belt, without requiring any person to reach beneath the belt. The method still further comprises removing the return roller from the return roller support assembly by sliding the return roller out from under the belt after the return roller has been lowered, without requiring any person to reach beneath the belt.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to bulk material belt conveyor systems. More specifically, this invention pertains to a return roller support assembly that is configured and adapted to allow return rollers to be serviced and removed while a conveyor belt is in operation. 
     2. General Background Technology 
     A bulk material belt conveyor comprises a belt that extends in a continuous loop. The upper portion of the continuous loop can be referred to as a transfer run and the lower portion of the continuous loop can be referred to as the return run. On the return run, the belt of a conveyor system is often supported from beneath by return rollers, which are typically idler rollers that roll with the belt. Like all moving components, return rollers occasionally need servicing or replacement. For example, servicing or replacement may be performed when the return rollers no longer rotate with ease, when their bearings get too loose, or when bulk material becomes caked on the rollers. In general, service and replacement of return rollers requires the conveyor belt to be shutdown to allow service personnel reach under the conveyor belt, which the Occupational Safety and Health Administration (OSHA) forbids while a conveyor belt is in operation. Logically, shutting down a conveyor belt system for any purpose decreases the efficiency of the system. 
     Another drawback associated with servicing return rollers is that the rollers are often fairly heavy and require more than one person to be removed. On conventional structures the return rollers are often mounted below the cat walk and there is almost never access to the far side. This makes service difficult and requires workers to climb in the conveyor structure and use safety harnesses to protect against fatal falls. Alternatively, boom trucks can be used to provide service personnel with access to the service rollers. Nonetheless, return rollers are heavy and bulky and therefore typically require two people to handle. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disadvantages associated with prior art return roller assemblies by providing apparatus and methods that allow return rollers to be easily serviced or replaced, without requiring the stoppage of conveyor belt systems. 
     In one aspect of the invention, a method comprises a step of accessing a conveyor belt system. The conveyor belt system comprises a belt, a return roller, and a return roller support assembly. The belt forms a continuous loop having an upper transfer run and a lower return run. The return roller has a weight that is supported by the return roller support assembly. The return roller is engaged with the belt from beneath the return run. The method also comprises a step of operating the return roller support assembly in a manner causing the return roller to lower relative to the belt to a position where the return roller is no longer engaged with the belt. This operation occurs without requiring any person to reach beneath the belt. The method still further comprises a step of removing the return roller from the return roller support assembly by sliding the return roller out from under the belt after the return roller has been lowered as recited. The removal also occurs without requiring any person to reach beneath the belt. 
     In another aspect of the invention, a conveyor belt system comprises a belt and a return roller assembly. The belt forms a continuous loop having an upper transfer run and a lower return run. The return roller assembly comprises a return roller and a support assembly. The return roller is rotationally mounted about a roller axis relative to the support assembly. The support assembly comprises a fixed portion and pivot portion. The fixed portion is fixed in position relative to the upper transfer run and the lower return run. The pivot portion is pivotally mounted to the fixed portion about a pivot axis. The return roller is removably attached to the fixed portion via the pivot portion in a manner such that the return roller is pivotal with the pivot portion relative to the fixed portion between engaged and disengaged positions. The return roller is engaged with the belt from beneath the return run when the return roller is in the engaged position and is spaced below the belt when the return roller is in the disengaged position. The return roller is also slidably attached to the pivot portion in a manner such that the return roller can be slid out from under the belt and from the support assembly. 
     Further features and advantages of the present invention, as well as the operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of a bulk material conveyor system. 
         FIG. 2  is a perspective view of a portion of a bulk material conveyor belt system having a return roller assembly in accordance an embodiment of the invention, and is shown with the return roller in its engaged position. 
         FIG. 3  is a side elevation view of the portion of the bulk material conveyor belt system shown in  FIG. 2 . 
         FIG. 4  is an elevation view of the portion of the bulk material conveyor belt system shown in  FIGS. 2 and 3 , as would be seen looking in a direction parallel to the direction of belt travel. 
         FIG. 5  is a detailed perspective view of the portion of the bulk material conveyor belt system shown in  FIGS. 2-4 , and is depicted without the belt. 
         FIG. 6  is a detailed perspective view similar to  FIG. 5 , but is shown with the return roller in its disengaged position. 
         FIG. 7  is a perspective view depicting the removal of the return roller from the portion of the bulk material conveyor belt system shown in  FIGS. 2-6 , and is depicted without the belt. 
         FIG. 8  is a detailed perspective view of an alternative embodiment of a return roller support assembly in accordance with the invention, and is shown with the return roller in its engaged position. 
         FIG. 9  is a view similar to  FIG. 8 , but is shown with the return roller in its disengaged position. 
     
    
    
     Reference numerals in the written specification and in the drawing figures indicate corresponding items. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A bulk material conveyor belt system is shown schematically in  FIG. 1 . The bulk material conveyor belt system  20  comprises a belt  22  that is driven about rollers  24  and forms a continuous loop. The upper portion of the continuous loop is referred to herein as the transfer run  26  and the lower portion of the continuous loop is referred to herein as the return run  28 . It should be appreciated that the direction arrows on  FIG. 1  are exemplary of a unidirectional conveyor but that the invention is applicable to reversing conveyors as well. The preferred orientation of the turnbuckle relative to belt travel is the direction which the belt runs most often as shown in  FIG. 1  or the direction that the belt runs when the return roller is serviced. The belt  22  generally travels along the return run  28  from the head  30  to the tail  32  of the conveyor (as is depicted with arrows). The bulk material conveyor belt system  20  further comprises one or more return roller assemblies  34  (represented schematically in  FIG. 1 ). The return roller assemblies  34  are configured to support the belt  22  from beneath return run  28 . 
     A portion of the bulk material conveyor belt system  20  having a return roller assembly  34  in accordance a first embodiment of the invention is shown in  FIGS. 2-7 . The portion of the belt  22  depicted in  FIGS. 2-4  lies along the return run  28 . The return roller assembly  34  comprises a return roller  36  and a support assembly  38 . The support assembly  38  comprises a fixed portion  40  and a pivot portion  42 . The fixed portion  40  is stationary relative to the main structural frame  44  of the conveyor belt system  20  is preferably suspended therefrom. The fixed portion  40  preferably comprises a pivot stop member  46  and a cross member  48  on each side of the opposite sides of the conveyor belt system  20 , which are located beyond the width of the belt  22  such that they are not positioned directly beneath the belt. Each of the pivot stop members  46  preferably has a pair of slotted bolt openings  50  and is preferably bolted to the respective cross member  48 . Each pivot stop member  46  and its respective cross member  48  are configured to created an elongate opening  52 . The slotted bolt openings  50  of the pivot stop members  48  allows the positions of the elongate openings  52  to be adjusted slightly along the direction of belt travel by loosening and the tightening the bolts  54 . The fixed portion  40  of the support assembly  38  also preferably comprises a pinch guard  56 , which is preferably a metal strip, that extends beneath the belt  22  and that is configured to prevent objects from becoming pinched between the belt  22  and the return roller  36 . In accordance with safety standards, the pinch guard is preferably adjustable in the vertical plane to maintain a gap of approximately 5 mm between the belt and guard. 
     The pivot portion  42  of the support assembly  38  comprises a torsion tube  58 , a track  60 , and a pair of swing arms  62 . The torsion tube  58  is pivotally mounted to each of the cross members  48  and is generally oriented horizontally and parallel to the widthwise direction of the belt  22 . The swing arms  62  are fixed to and extend radially up from torsion tube  58 . The swing arms  62  pass through the elongate openings  52  that are formed by the cross members  48  and the pivot stop members  46 . The track  60  is fixed to each of the swings arms  62  and extends generally parallel to the torsion tube  58 . For purposes explained below, the swing arms  62  are slightly skewed from being parallel when the torsion tube  58  is not deflected. The track  60  is preferably formed of steel angle iron. A pair of button heads  64  are fixed to the track adjacent one of the longitudinal ends of the track. A pair of removable detent pins  66  are releasably attached to the track  60  adjacent the other longitudinal end of the track. 
     The return roller  36  comprises a roller body  68 , an axle  70 , a pair of roller arms  72 , and a sleeve member  74 . The roller body  68  can be cylindrical (as shown), helical, convex, or any other shape or combination of rollers desired. The roller arms  72  are mounted to opposite ends of the axle  70  in a manner such that the roller body  68  is pivotally connected to the roller arms. The sleeve member  74  preferably extends parallel to the axle  70  and is fixed to each of the roller arms  72 . The sleeve member  74  is configured to mate with the track  60  of the pivot portion  42  of the support assembly  38 , in a manner securing the return roller  36  to the pivot portion. 
     The return roller assembly  34  also comprises a pivot mechanism  76  that is connected to both the pivot portion  42  and the fixed portion  40  of the support assembly  38 , preferably on the side having the detent pins  66  connected to the track  60 . The pivot mechanism  76  comprises a turnbuckle  78  that is pivotally connected to the pivot portion  42  and to the fixed portion  40  of the support assembly  38 . The turnbuckle  78  is adjustable in length, which when adjusted allows the pivot portion  42  to pivot relative to the fixed portion  40 . However, the pivot stop members  46  of the fixed portion  40  limit the extent to which the pivot portion  42  can pivot in either direction by engaging against the swing arms  62 . One limit is shown in  FIG. 6  and is referred to herein as the disengagement position. The other limit is shown in  FIG. 5  and is referred to herein as the engagement position. 
     The return roller  36  is assembled to the support assembly  38  when the pivot portion  42  is in the disengagement position. The configuration of the support assembly  38  is often dictated by the conveyor design but can be adjustable to facilitate proper location of the assembly below the belt. This is done with the detent pins  66  removed from the track  60 . With the detent pins  66  removed, the sleeve member  74  of the return roller  36  is slid onto the track  60 , as shown in  FIG. 7 . The button heads  64  at the opposite end of the track  60  ultimately prevent the sleeve member  74  from sliding along the track beyond a limit. Once this limit is reached, the detent pins  66  are inserted back into the track  60 , where they prevent the sleeve member  74  from sliding back off of the track. The turnbuckle  78  of the pivot mechanism  76  is then operated to pivot the pivot portion  42  together with the return roller  36  toward the engagement position. As the pivot portion  42  approaches the engagement position, the swing arm  62  on the side of the conveyor belt system  20  opposite the pivot mechanism  76  contacts its respective pivot stop member  46  before the swing arm on the same side as locking mechanism does. This is due to the swing arms  62  being slightly skewed from each other as mentioned above. The pivot mechanism  76  then torques the torsion tube  58  as the swing arm  62  nearest the pivot mechanism approaches engagement with its respective pivot stop member  46 . This resiliently deflects the torsion tube  58  torsionally. Once the swing arm  62  nearest the pivot mechanism  76  engages its respective pivot stop member  46 , the pivot portion of the support assembly  38  and the return roller  36  are in the engaged position. It should be appreciated that the torsional deflection of the torsion tube  58  firmly biases the swing arm  62  opposite the pivot mechanism  76  against its respective pivot stop member  46  with sufficient force to resist the tangential forces created by the belt and roller interaction. This eliminates any movement in the system, and thereby ensures that the roller is properly aligned with the belt under normal operating conditions. In prior art systems it, belt flap (vibration at the natural frequency of the belt) can cause the sleeve  74  to chatter on track  60 . The clamp bar system of the present invention eliminates slop and prevents such chatter. 
     In the engaged position, the roller body  68  of the return roller  36  engages the belt  22 . When the return roller  36  needs servicing, the above-described process is reversed. To do this, the pivot mechanism  76  is actuated so as to pivot the return roller  36  to the disengaged position. This lowers the return roller  36  and separates the roller body  68  from the belt  22  by a sufficient amount that allows for the removal of the return roller. The sleeve  74  preferably extends the length of the return roller  36  so that the return roller can not accidentally contact the belt when the return roller is being removed during operation of the conveyor belt system. In the disengaged position, the swing arms  62  again engage the pivot stop members  46 , which provides confirmation that return roller  36  has been sufficiently lowered. In the event that there is slack in the belt  22 , the pinch guard  56  will engage the belt and ensure that that the belt remains sufficiently spaced from the return roller  36 . In the disengaged position, the detent pins  66  can then be removed, thereby allowing the return roller  36  to be slid off the track  60 . The return roller  36  can then be repaired or replaced. It should be appreciated that the assembly can be guarded with a barrier guard such as a wire mesh screen. In such situations, an opening can be provided in the guard such that the return roller  36  can only be withdrawn when in the disengaged position. Preferably, such an access opening would require a tool for opening so that non-authorized personnel cannot easily attempt to service the return roller. 
     An alternative embodiment of a return roller support assembly in accordance with the invention is shown in  FIGS. 8 and 9 . This alternative support assembly  80  differs primarily in that its pivot mechanism  82  comprises gears rather than a turnbuckle. More specifically, the support assembly  80  comprises a first toothed gear  84  and a second toothed gear  86 . The first toothed gear  84  is formed as part of one of the swing arms  88  and is attached to the end of the torsion tube  90  in a manner such that it is aligned with the pivot axis thereof. The second toothed gear  86  is pivotally mounted to the cross member  92  of the fixed portion  94  of the support assembly  80  and is engaged with the first toothed gear  84 . A lever arm  96  is attached to the second toothed gear  86  for rotation therewith. When the pivot portion  98  of the support assembly  80  is in the engaged position (shown in  FIG. 8 ), the lever arm  96  extends vertically upwards, where it can act in place of the above-described detent pins to prevent the return roller (not shown) from backing off of the track  100  of the pivot portion  98  and prevent service while the roller is in the engaged position. The pivot portion  98  can be moved to the disengaged position by pivoting the lever arm  96  to the position shown in  FIG. 9 . To maintain the pivot portion  98  of the support assembly  80  in either the engaged or disengaged positions, the lever arm  96  comprises a slot  102  that is adapted to receive a detent pin (not shown). In the engaged position, the slot  102  is aligned with a detent hole  104  that is formed in the swing arm  88 . In the disengaged position, the slot  102  is aligned with a detent hole  106  that is formed in the cross member  92 . In either case, a detent pin can be placed through the slot  102  and corresponding detent hole  104 ,  106  to prevent the lever arm  96  from pivoting. 
     In view of the foregoing, it should be appreciated that the invention achieves the several advantages over prior art methods and devices. It should also be appreciated that the invention allows return rollers to be serviced or replaced while a conveyor belt system is in operation. Still further, it should be appreciated that the invention allows return rollers to be replaced or serviced easily from just one side of a conveyor belt system and the system can be made to work on the right or left hand of the conveyor by the addition of a second pivot mechanism attachment opposite the one shown in the drawings. 
     As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents. 
     It should also be understood that when introducing elements of the present invention in the claims or in the above description of the preferred embodiment of the invention, the terms “comprising,” “including,” and “having” are intended to be open-ended and mean that there may be additional elements other than the listed elements. Additionally, the term “portion” should be construed as meaning some or all of the item or element that it qualifies. Moreover, use of identifiers such as first, second, and third should not be construed in a manner imposing any relative position or time sequence between limitations. Still further, the order in which the steps of any method claim that follows are presented should not be construed in a manner limiting the order in which such steps must be performed.