Abstract:
A compensating roller system is adapted to adjust to size variation of product moving through a conveyor system. In one example, the compensating roller system is used to control a force resulting in deflection of a conveyor belt. In a specific implementation of such an example, a first rail is configured to support a first conveyor belt. A plurality of rollers is attached to the first rail and supports a conveyor belt moving over the rollers. The attachment allows each roller to pivot independently of movement of other rollers. Each of the rollers&#39; movement is against a bias, and allows for deflection of the conveyor belt. A second rail may be configured as the first rail, and oriented define a channel for product movement between conveyor belts carried by the first and second rails.

Description:
RELATED APPLICATIONS 
   This patent application claims priority to U.S. patent application Ser. No. 60/743,254, titled “Case Sealer with Compensating Roller System”, filed on Feb. 8, 2006, commonly assigned herewith, and hereby incorporated by reference. 

   BACKGROUND 
   Conveyor systems using one or more belts are frequently used to move product between locations. In some applications, boxes are moved by a conveyor system having two conveyor belts configured so that one conveyor belt is in contact with each of two opposite sides of a box. Additionally, a passive third conveyor or rollers support a bottom surface of the box. For example, the left and right sides of a box may be in contact with driven conveyor belts, while the bottom of the box moves passively on a lower conveyor belt or rollers. By separating the left and right driven conveyor belts by a distance related to the width of the box moving within the conveyor system, friction between the left and right conveyor belt will move the box through the conveyor system. 
   Unfortunately, it is common for the dimensions of product, such as the boxes moving within the conveyor system of the above example, to vary. This can result in application of excessive friction and pressure to larger boxes, and inadequate friction and pressure to smaller boxes. 
   Accordingly, a need exists for improved conveyor systems and components within such systems. 
   SUMMARY 
   A compensating roller system is configured for use in applications, such as use in a conveyor system, wherein one or more rollers are configured to move against a bias. In an application utilizing a conveyor belt, rollers within the compensating roller system support an inside surface of the conveyor belt. A bias controlling deflection of individual rollers is used to oppose a force resulting in deflection of the conveyor belt. In such an application, movement of the rollers supporting the conveyor belt against their bias compensates for size variation of product moved by the system. 
   This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended for use as an aid in determining the scope of the claimed subject matter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. 
       FIG. 1  shows an isometric view of an example of a conveyor system having two opposed conveyor belts, shown moving a box. 
       FIG. 2  shows an orthographic view of the conveyor system of  FIG. 1 . 
       FIG. 3  shows an enlarged view of an example of a tail roller assembly shown in  FIG. 2 . 
       FIG. 4  shows an enlarged view of an example of a roller assembly shown in  FIG. 2 . 
       FIG. 5  shows an enlarged view of an example of a belt-supporting roller assembly shown in  FIG. 2 . 
       FIG. 6  shows an enlarged view of an example of a drive roller shown in  FIG. 2 . 
       FIG. 7  shows an example method by which a compensating roller system may be operated. 
   

   DETAILED DESCRIPTION 
   Overview 
   The following discussion is directed to a compensating roller system. In one example, the roller system is configured as part of a conveyor system. In such an application, rollers within the compensating roller system support a conveyor belt. A bias controlling deflection of individual rollers is used to control a force resulting in deflection of the conveyor belt. Thus, movement of the rollers supporting the conveyor belt compensates for size variation of product moved by the system. 
   Example Construction 
     FIG. 1  shows an example of a conveyor system  100  configured with a compensating roller system. In the conveyor system shown, a box  102  (not part of the conveyor system) is moving from the upper left to the lower right. The box is propelled by movement of the two opposed conveyor assemblies  104 ,  106 . The two opposed conveyor assemblies  104 ,  106  are separated by a distance, thereby forming a channel for product travel, which is incrementally less than the width of the box  102 . Accordingly, a conveyor belt  108  moving within each conveyor assembly  104 ,  106  makes frictional contact with the box  102 , thereby driving the box through the conveyor system  100 . 
     FIG. 2  shows an orthographic view of the conveyor system  100  of  FIG. 1 . A box  102  is shown moving from left to right.  FIG. 2  shows an example of the orientation of several component parts of the conveyor system  100 , including tail roller assemblies  110 , roller assemblies  112 , belt-supporting roller  114  and drive roller  116 . Accordingly, product, such as the box  102 , enters the conveyor system  100  at the tail roller assembly  110 . The product passes a number of roller assemblies  112 , with which the conveyor belt  108  is in contact. Belt-supporting roller assemblies  114  apply a tension to the belt  108 , keeping the belt in contact with rollers within the roller assemblies. In the example of  FIG. 2 , the drive roller  116  is supported in a fixed location relative to a rail  118 , which forms a frame for each conveyor assembly  104 ,  106  ( FIG. 1 ). 
     FIG. 3  shows an enlarged view of an example of the tail roller assembly  110  shown in  FIG. 2 . Each tail roller assembly  110  is configured to include a tail roller  302  that pivots slightly from a resting, or default, position to increase a distance between the two tail roller assemblies of the two conveyor assemblies  104 ,  106 , respectively (as seen in  FIG. 2 ). The example tail roller assembly  110  of  FIG. 3  includes a tail roller  302  mounted to revolve about a tail roller axle  304 . The tail roller axle  304  is supported for movement by a tail roller pivot arm  306 , which pivots about a tail roller pivot arm axle  308 . The location of the tail roller pivot arm axle  308  is finely controlled by an adjustment element, which allows the tail roller pivot arm axle to be moved in a direction parallel to the rail  118 . One effect of such movement is to tension the conveyor belt  108 . In the example of  FIG. 3 , the tail roller pivot arm axle adjustment element is an adjustment bolt  310 , which may be mounted in a threaded passage through a pivot arm bolt support  312 , which may be secured to the rail  118 . 
   Movement of the tail roller  302  and pivot arm  306  is resisted by a spring  314  or other biasing element. In the example of  FIG. 3 , the spring  314  is attached to the rail  118  at a mount  316 . Thus, contact with a box  102  or other product moving through the conveyor system  100  can result in deflection of the tail roller  302  and pivot arm  306  about pivot  308  and against the bias of spring  314 . 
   In the example of  FIG. 3 , the pivot  308  is located slightly off-center. That is, pivot  308  is closer to one side (the upper side, in  FIG. 3 ) of the belt  108  than to the other side of the belt. The off-center location of the pivot  308  reduces movement of the pivot arm  306  against the bias of the spring  314 . 
   Continuing to refer to  FIG. 3 , a secondary tail roller  318  may be provided. In the example of  FIG. 3 , the secondary roller  318  is supported by an axle  320  attached to a secondary tail roller pivot arm  322 . The pivot arm  322  pivots slightly about an axle  324 , which is fixed relative to the rail  118 . Movement of the pivot arm  322  is damped by a spring  326  or similar biasing element. 
     FIG. 4  shows an enlarged view of an example of the roller assembly  112  shown in  FIG. 2 . A roller  402  is in contact with an inner surface of the belt  108 . The roller is attached to a pivot arm  404  at the axle  406 . The pivot arm  404  pivots at pivot  408 , which is fixed with respect to the rail  118 . Movement of the pivot arm  404  is biased by spring  410  or similar biasing element. Thus, when a box or other product moving through the conveyor system is wider than a distance separating the conveyor assemblies, the conveyor belt  108  deflects slightly, deviating from a nominal course of travel. Accordingly, the biasing element  410  resists pivotal movement of the roller  402  and deflection of the conveyor belt  108 . Such deflection is made possible by the movement against bias of one or more rollers  402 , which in most applications are configured to move independently. Note that in the example of  FIG. 4 , adjacent rollers  402  are allowed movement independent of each other; that is, the pivot arms  404  are typically not linked. Because of the orientation of the pivot arms  404 , the direction of the pivot includes a component direction that is parallel to a direction of product flow through the conveyor system. Another component direction is perpendicular to the flow, allowing the space (channel) within which product travels to be increased. Looked at another way, each roller  402  moves both back (i.e. in the direction of product travel) and away (i.e. away from the product/box in the channel between conveyor assemblies) as the spring  410  is compressed. In a typical application, the movement away from the product/box in the channel exceeds an expected variation in a size of product moving through the conveyor system. 
   In an alternative construction, two or more adjacent rollers  402  may be linked together, in a manner that results in a mutual movement. The structure linking adjacent rollers together may depend on the application; however, links similar to the linkages  510 ,  512  seen in  FIG. 5  could be used to link together one or more adjacent rollers  402 . In this construction, the linked rollers  402  would operate “in concert” or as a “gang” and tend to deflect in unison in response the deviation from the nominal course of travel of the conveyor belt  108 . Such deviation in the conveyor belt  108  could be caused by travel of an oversized object through the channel defined between opposed conveyor assemblies  104 ,  106 . 
   Continuing to refer to  FIG. 4 , the rail  118  may be constructed of a variety of materials, such as steel or synthetic products. In one application, at least a portion of the rail may be made of a synthetic product such as Nylatron®. In such an application, each pivot arm  404  may be supported by an axle  408  that fits loosely within a hole  412  defined in each pivot arm. As the pivot arm moves during operation, an outer surface of each pivot arm  404  is then seated against a bearing surface  414 . Where an appropriate material is selected for the portion of the rail defining the bearing surface, the pivot arm  404  may move with a satisfactory amount of support and friction. In one example of such a configuration, the axle  408  and pivot arm  404  could both be made of steel, while the bearing surface  414  is made of a softer material. 
   A review of  FIGS. 3 and 4  indicates that the tail roller  302  is configured to pivot against bias in a direction opposite to pivotal movement against bias of the rollers  402 . In the example of  FIGS. 3 and 4 , the tail roller  302  pivots about  308  in a clockwise direction against the bias of spring  314 . In contrast, the rollers  402  pivot counterclockwise against the bias of spring  410 . 
     FIG. 5  shows an enlarged view of an example of a belt-supporting roller assembly  114  shown in  FIG. 2 . The belt-supporting roller assembly  114  is particularly useful in longer conveyor assemblies  104 ,  106 , wherein the belt  108  may be more likely to separate from the one or more rollers  402 . A roller  502  adjusts a path followed by the belt  108  to create a deflected belt segment or local deformation  504 , i.e. a section of the belt  108  wherein the belt is deflected slightly in a manner that promotes contact between the belt and one or more rollers  402  in both directions adjacent to the roller  502 . The roller  502  is supported by a pivot arm  506 , which moves about pivot  508 . In some applications, movement of the pivot arm  506  may be restricted by at least one of a forward linkage  510  and a rearward linkage  512 . The linkages may be a single rigid connector, or may be formed from two links with a pivot between the links. In the example of  FIG. 5 , the linkages  510 ,  512  are connected to the pivot arm  506  of the belt-supporting roller  502  and the pivot arm  404  of a roller assembly  112  forward and rearward of the belt-supporting assembly  114 . The linkages  510 ,  512  tend to cause the roller  502  to move in unison with the rollers  402  immediately forward and rearward of the roller  502 . 
     FIG. 6  shows an enlarged view of the example of the drive roller assembly  116  shown in  FIG. 2 . The assembly  116  may include a drive roller  602 , typically attached by an axle  604  to the rail  118 . In the example of  FIG. 6 , the axle  604  is located to result in a slight deflection of the belt  108 , shown as theta at  606 . Such a deflection, or course or direction change, of the belt  108  results in a gradual lessening of the friction between the belt and box or other product  102  moving through the conveyor system  100  ( FIGS. 1 and 2 ). 
   In some implementations, the drive roller  602  is constructed at least in part of a resiliently deformable material. The resiliently deformable, or highly frictional, material increases the frictional contact with the belt  108 , thereby more effectively driving the belt. In one example, a rubber coating on the drive roller could provide a more highly frictional contact between the drive roller  602  and the belt  108 , thereby reducing slippage of the belt. 
     FIGS. 1 and 2  illustrate an implementation having two opposed conveyor assemblies  104 ,  106 . In such applications, the opposed assemblies  104 ,  106  may engage opposed sides of product (such as a box), while passive rollers (not shown) support the products as it is moved by the assemblies. However, in other applications, only a single conveyor assembly is used. In such applications, it is possible for the product to be supported by the single assembly, which then both moves and supports the product. 
   Example Operation 
   Referring to  FIG. 7 , example aspects  700  of the operation of the example conveyor system  100  can be seen. At block  702 , a box or other product enters a conveyor system. For example, in the conveyor system of  FIG. 1 , a box  102  is shown moving from left to right, entering the conveyor system  100  at the tail roller assembly  110  and leaving at the drive roller assembly  116 . At block  704 , one or more tail rollers deflect in response to contact with the box or other product. An example of such deflection can be understood with reference to  FIG. 3 , wherein contact with a box can result in the tail roller  302  deflecting slightly in a direction that compresses the spring  314 . Thus, the distance between two opposed tail rollers  302  of two conveyor assemblies  104 ,  106  is increased. Note that location of the pivot arm axle  308  off-center (i.e. closer to the portion of the belt adjacent spring  314  than to the portion of the belt on the opposite side) prevents the tail rollers of opposed conveyor assemblies  104 ,  106  from seeking a resting position close to each other. That is, the resting position of each tail roller  302  is to contact, but not compress, an associated spring  314 . 
   At block  706 , the box  102  is moved through the conveyor system  100  by frictional contact with the belts  108 . The belts move along the rollers  402 , which are configured for resilient deflection in response to contact with the box or other product. For example, the rollers will deflect slightly in response to the size of the box applying a force to the conveyor belt. Referring to  FIG. 4 , it can be seen that if the box  102  is slightly larger than the space between the conveyor assemblies  104 ,  106 , then some deflection of the rollers  402  will result. Deflection of each roller  402  will result in some compression of the associated spring  410 . Accordingly, deflection results in friction between the belt  108  and box  102 , ensuring movement of the box  102  within the conveyor system  100 . 
   At block  708 , the conveyor belt is kept tight against the rollers by one or more belt-supporting assemblies. Referring to  FIG. 5 , as the belt  108  moves in a circuitous path, it moves through the belt-supporting roller assembly  114 . The belt-supporting roller  502  tends to support the belt  108  against the compensating rollers  402 . Thus, a distribution of one or more belt-supporting roller assemblies  114  along the conveyor belt  108  tends to keep the belt in contact with most or all rollers  402 . At block  710 , the supporting roller  502  deflects in concert with adjacent rollers  402 , in response to force conveyed by the linkage(s)  510 ,  512 . Such a force could result from movement of an oversized box through the conveyor system. 
   At block  712 , as the box  102  leaves the conveyor system  100  it passes the drive roller  602 .  FIG. 6  shows an example drive roller. Due to the angle theta seen at  606 , the distance between belts  108  of the two conveyor assemblies  104 ,  106  widens slightly, and the box is released. 
   CONCLUSION 
   Although aspects of this disclosure include language specifically describing structural and/or methodological features of preferred embodiments, it is to be understood that the appended claims are not limited to the specific features or acts described. Rather, the specific features and acts are disclosed only as exemplary implementations, and are representative of more general concepts.