Abstract:
An improved roller assembly for use in machinery such as round balers is disclosed. The roller assembly of the present invention reduces sensitivity to varying dimensional tolerances on the roller assembly and the structure to which the roller assembly is mounted. At least one elastic member is used to permit the axial position of at least one of the bearings on the roller assembly shaft to vary. Spring washers provide a predetermined, axial force to at least one of the bearings.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0001]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a mounting arrangement for a roller, with an effective length that varies with a standard manufacturing tolerance, where the roller mounts between a pair of supporting panels spaced apart a distance that varies with a standard manufacturing tolerance. Machines used for forming agricultural crops into cylindrical bales, known as round balers, have historically been constructed including such rollers. The size of the panels and the spacing between the panels are such that normal manufacturing tolerances affect the roller mounting such that the bearings can be subject to axial loading generated by assembly of the components.  FIG. 1  illustrates a prior art roller mount arrangement where a roller  100  is supported by two bearings  102 ,  106  mounted to two panels  10 ; a drive-side bearing  102  on the drive side where a drive sprocket  104  is mounted to the roller  100  and an idler-side bearing  106  on the side opposite the drive sprocket  104 . In this mounting arrangement, although not apparent from this figure, the bearings and mating shafts of the roller are round in cross-section, in which the inner race of each bearing will be secured to the roller in some manner to prevent relative rotation between the bearing and the shaft, in both axial and radial directions.  
         [0003]     In addition, axial movement of the drive-side bearing  102  relative to the shaft is limited when a drive end bolt  108  is installed into a threaded hole in the shaft of the roller  100  and tightened, sandwiching the bearing  102  and sprocket  104  between an end-cap  110  and a shoulder  112  of the roller. Axial movement of the idler-side bearing  106  is limited when an idler end bolt  116  is installed into a threaded hole in the shaft of the roller  100  and tightened, sandwiching the idler-side bearing  106  between an end-cap  118  and a shoulder  114 . The distance between the two shoulders  112 ,  114  and the distance between the panels  10  will vary with a manufacturing tolerance. If the roller is too long, the distance between the shoulders  112 ,  114  too large, and if the bearing flanges  103 ,  107  were simply bolted to the panels  10 , the bearings  102 ,  106  would be subject to axial loads generated as the bolts supporting the bearing flanges were tightened. To avoid this situation, this prior art design utilizes an assembly wherein the bearing flange  107  is bolted to a bracket  120  which can be moved relative to the panel  10  due to slotted apertures in angles  122 , in order to match the dimension required by the distance between shoulders  112 ,  114 . The assembly process is completed in the following order: first, the drive side bearing  102  and sprocket are secured to the roller  100  with the drive end bolt  108  and the end-cap  110 , and the bearing flange  103  is secured to the panel  10 ; second, the idler side bearing  106  is secured to the roller with the idler end bolt  116  and the end-cap  118  and the bearing flange  107  is secured to the bracket  120 ; lastly, the bracket  120  is secured to the angles  122 , that were previously secured to the panel  10 , with a bolt  124 . This assembly of the bracket  120 , angles  122  and bolt  124  allows the bearings  102 ,  106  to be positioned to match the spacing between shoulders  112 ,  114 . This assembly utilizes several components to achieve this adjustment. An improved assembly would reduce the number of components.  
         [0004]     A second prior art design is illustrated in  FIG. 2  wherein the bearings  202 ,  206  support a roller  200 , and are mounted to brackets  222  that are secured to the panels  10 . Each bearing is secured to the roller  200  with a drive end bolt  208  and an end-cap  210 , tightening the inner races of the drive-side bearing  202  against a drive-side shoulder  212  and the idle-side bearing  206  against an idle-side shoulder  214 . A drive side spacer  216  is utilized to position the roller such that the sprocket  204  is secured with the bolt  208  and end-cap  210  on the drive side. After the drive side spacer  216 , bearing  202 , and sprocket  204  are assembled on the roller and secured to the bracket  222 , the idler side is assembled by selecting an idler side spacer  218  that is the correct length such that the bearing flange  207  will contact the bracket  222  at approximately the same location as the inner race of the idler side bearing  206  will contact the idler side spacer  218 . The idler side bearing flange  207  is secured to the bracket  222  and then the bolt  208  and end cap  210  are installed in the idler side. If the idler side spacer  218  is too short, tightening the bolt  208  will result in axial loading of the bearings equal to the force generated by the bolt  208 . If the idler side spacer  218  is too long, it will restrict the travel of the bearing flange  207  to the bracket  222 , and an axial load will have been generated when the flange mounting bolts were tightened. Thus, in this arrangement, the proper selection of the spacer  218  is critical. An improved assembly would reduce the critical selection of spacers.  
         [0005]      FIG. 3  illustrates a prior art design of a roller mount arrangement that has been used for conveyors, wherein a roller  300  is supported by bearings  302  and a shaft  304 . The shaft  304  is constructed from raw material with a hexagonal cross-section, so that the ends will fit into slots in the supporting panels  310  to be held in position while also held from rotating, as a result of the faces of the hexagonal cross-section mating with the slot. In order to simplify installation of the roller assembly, the shaft  304  is allowed to slide axially in a hexagonal inner bore of the bearings  302  and is spring-loaded prior to installing the roller assembly into the panels. The roller assembly includes springs  306 , snap rings  308  and washers  312  that cooperate to apply a spring force onto the inner race  303  of the bearing  302 . In order to assemble the roller assembly between the supporting panels  310 , the shaft  304  on a first side is installed in a receiving aperture in the first side support panel  310  while the shaft  304  is pushed inwards on the opposite side, further compressing the spring  306  on the first side, until the end of the shaft  304  will fit between the supporting panels. As the roller assembly is moved into its proper installed position the shaft  304  will then extend, once properly aligned, with the aperture in the second supporting panel  310 . In the final installed position both springs  306  are preloaded to apply a force on the inner race of the bearings to stabilize the shaft and bearings.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     According to the present invention there is provided a method and apparatus for reducing the sensitivity to machine tolerance in a roller assembly used in a round baler. To effect this method and apparatus, elastic components are included, allowing variation in the length of the assembly while still providing the appropriate axial load on the fasteners at the ends of the roller shaft.  
         [0007]     In one embodiment, the bearing on the end of the shaft on which the sprocket is mounted is rigidly fastened by its flange to a bracket providing an interface between the bearing flange and the panels between which the roller is mounted. The bearing receives an axially-directed force from a spring washer loaded by a bolt to maintain its axial position.  
         [0008]     At the opposite end of the roller shaft, the bearing flange is, again, rigidly mated to a bracket. However, the axial position of the bearing is permitted to vary due to the elasticity of a spring or springs on the inner side of the inner bearing race.  
         [0009]     In a separate embodiment, a spring washer applies a force to the outer side of the inner bearing race of the bearing opposite the sprocket, thereby providing a flexible restriction to axial movement of the bearing.  
         [0010]     In still another embodiment, the spring or springs are replaced by shims, but the spring washers are still used at each end of the roller shaft. At the drive end, the perimeter of the spring washer bears on the sprocket and is forced into the end of the shaft with a bolt. On the opposite end of the shaft, the perimeter of the spring washer bears on the outer side of the inner bearing race while it is forced into the end of the shaft by a bolt. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a cross sectional view of a first prior art mount arrangement;  
         [0012]      FIG. 2  is a cross sectional view of a second prior art mount arrangement;  
         [0013]      FIG. 3  is a cross sectional view of a third prior art mount arrangement;  
         [0014]      FIG. 4  is a first cross sectional view of a mount arrangement showing a complete roller assembly of the present invention;  
         [0015]      FIG. 5  is a second cross sectional view of a mount arrangement showing a complete roller assembly of the present invention;  
         [0016]      FIG. 6  is a third cross sectional view of a mount arrangement showing a complete roller assembly of the present invention;  
         [0017]      FIG. 7  is a cross sectional view of one side of a mount arrangement prior to installation of the spring washer of the present invention;  
         [0018]      FIG. 8  is a cross sectional view of one side of a mount arrangement including a spring washer of the present invention;  
         [0019]      FIG. 9  is a cross-sectional view of the mount arrangement taken along line  9 - 9  of  FIG. 4 ;  
         [0020]      FIG. 10  is a cross-sectional view of the mount arrangement taken along line  10 - 10  of  FIG. 5 ; and  
         [0021]      FIG. 11  is a cross-sectional view of the mount arrangement taken along line  11 - 11  of  FIG. 6 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     Referring now to the drawings wherein like reference numerals designate identical or corresponding parts throughout the several views. The included drawings reflect the current preferred and alternate embodiments. There are many additional embodiments that may utilize the present invention. The drawings are not meant to include all such possible embodiments.  
         [0023]      FIG. 4  illustrates a roller  400  supported by two bearings  402 ,  406 , mounted to brackets  222  secured to panels  10  wherein the roller shaft  480  is hexagonal in cross-section, the bearings have mating hexagonal inner bores as shown in  FIGS. 9, 10 , and  11 . The hexagonal cross-section shaft  480  and mating bore secure the bearing onto the roller shaft  480  rotationally, eliminating relative rotation between the shaft  480  and bearings  402 ,  406 . A stop or shoulder  412  is provided against which to bear components on the shaft  480 . The stop or shoulder  412  may be formed by machining, or a disc or ring may be fastened to the shaft  480 . On the drive side, the right side in  FIG. 4 , the sum of the axial length of the spacer  416 , width of the drive side bearing  402 , and thickness of the sprocket  404  is slightly longer than the length of the shaft  480  between shoulder  412  and the end  413  of the shaft  480  so that there is at least a slight clearance  415 , as illustrated in  FIG. 7 . The bearing flange is secured to the bracket  222 , locating the roller  400  relative to the panels  10 . The components that are mounted onto the shaft  480  are secured axially with a retention system of the present invention comprising a bolt  408 , a spring washer  450 , washers  452  and an end-cap  410 . The components mounted to the shaft  480  between the end-cap  410  and the shoulder  412  of the shaft  480  are clamped together with a force defined by the properties of the spring washer  450  which is deflected from a normally flat shape into the deformed shape as illustrated in  FIG. 8  where washers  452  act to force it to the left, as the bolt  408  is tightened, while the outside surface  405  of the sprocket  404  restricts the outer periphery of the spring washer  450  from moving further to the left. The spring force generated is a function of the modulus of elasticity of the material from which the spring washer  450  is constructed, the difference between the outer diameter of the washers  452  and the inner diameter of the bore in the sprocket  404 , and the clearance  415  that is illustrated in  FIG. 7 . These variables can be selected to provide the desired spring force.  
         [0024]     After the drive side is so secured to the bracket  222 , the idler side is assembled by installing a spacer  418  and springs  440  onto the shaft  480  of the roller  400  as illustrated in  FIG. 4 . The springs  440  shown in this embodiment are Bellville springs; other types of springs  440  could be used including coil compression springs. A single spring or a plurality of springs may be employed. The overall assembly of the spacer  418  and the spring  440  are of sufficient length that the inside surface of the inner race  485  of the bearing  406  will contact the spring before the flange  407  contacts the plate  222 . As the bearing flange  407  is secured to the bracket  222 , the bearing  406  will be drawn up such that it is in contact with the bracket  222  after the inner race  485  has contacted the spring  440 . This will result in compression of the spring  440 , which will generate an axial load on the inner surfaces of the inner races  485  of both bearings  402 ,  406 . This axial loading will be consistent and controlled, while not requiring special attention during the assembly process. The spring force generated from the compressing spring  440  will provide adequate stability of the bearing/roller interface. An advantage of this arrangement is that the spring  440  eliminates the potential of excessive axial loading generated when the idler side bearing  406  is installed. The possibility of generating an axial load is inherent with a design where the spacing between the support panels is fixed with a tolerance, and the length of the roller  400  is fixed with a tolerance. This embodiment will generate a known, predictable loading that can be used to stabilize the inner races  485  of both bearings  402 ,  406 .  
         [0025]      FIG. 5  illustrates an embodiment of the present invention wherein a spring washer  451  has been added, acting on the outside surface of the inner race  485  of the bearing  406 , in addition to the spring washer  450 , as described for  FIG. 8 , acting on the drive side, stabilizing the bearing/shaft interface.  
         [0026]      FIG. 6  illustrates an embodiment wherein the components of the present invention are alternately combined, where the spring between the spacer  418  and the inner race  485  of the bearing  406  has been removed, and replaced with shims  441 . In this embodiment the position of the side panel  10  relative to the idler side bearing  406  is constrained when the assembler, while installing the bearing  406 , will take measurements and select the correct number of shims  441  to assure that the bearing  406  can be mounted to the bracket  222  before its inner race  485  contacts the shims  441 , while minimizing the clearance. Spring washers  450 ,  451  are installed, along with washers  452 , on both sides to generate a spring force which acts on the inner race  485  of both bearings  404 ,  406  to stabilize the bearing/shaft interface, while limiting the axial force applied to the bearings  404 ,  406 .  
         [0027]     Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.