Patent Document

FIELD OF THE INVENTION  
         [0001]    The present invention relates to a self-containing full-complement roller bearing cage.  
         BACKGROUND OF THE INVENTION  
         [0002]    A self-containing cage for a rotative roller bearing is known, which has two side plates fastened to each other by means of bolts and which contains cylindrical rollers, the ends of which penetrate at either side into a deepening of an adjacent side plate (US PS 502025). At this known cage the bolts are placed between the rollers, so that neighbored rollers have a relatively large distance between each other around the circumference, thus only a relatively small number of rollers can be built into the bearing which often causes a too small load carrying capacity of the bearing per unit length of raceway.  
           [0003]    Another self-containing cage for a rotative roller bearing is known, which has hollow cylindrical rollers, each roller having a through-going central hole, whereby a bolt penetrates axially through each hole and both ends of each bolt are rigidly fastened onto a side plate at the corresponding side of the cage (US PS 236517). This other known cage can be made as a full-complement unit, so that it contains an optimal large number of rollers on its circumference. However, an important disadvantage is to be seen in the fact, that every roller must be slidingly held and centered on its bolt during bearing operation. The contacting sliding surfaces between roller and bolt are difficult to maintain continuously lubricated with the indispensable lubricant, grease or oil, because in case the flowing lubricating medium is placed between the hole and the bolt it will be flung out of the bore of the rotating roller by the effect of centrifugal force, the medium flings radially outwardly, thereby being taken away from the sliding surfaces of the bore of the roller, where it is intended to lubricate and to protect against sliding wear. Therefore, in this other known cage there can develop easily a detrimental sliding wear in the bore between roller and bolt, which makes the sliding gap between the rollers and the bolt growing larger. The rollers of the cage then begin to inadmissibly oscillate during operation and to run obliquely. This again adds to the wear in the roller bores, thus this wear becomes greater and increases faster. Especially during running with high bearing load, there is produced an additional parasitical contact wear on the raceways of the roller bearing, because the obliquely running rollers do not roll properly on their raceways. In some cases where the oblique position of the rollers in the known cage has become great enough, these rollers may even produce a catastrophical blockade of the bearing during operation.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0004]    One object of the present invention is therefore to establish a self-containing full-complement bearing of the defined kind, in which the sliding wear in the flow medium lubricated cage is considerably reduced, in as much as a detrimental greater oblique position of the rollers in the cage is avoided even during long operation time and heavy bearing load.  
           [0005]    A further object of the present invention is to provide a cage which can be manufactured extremely economically by using simple manufacturing means.  
           [0006]    With the cage of this invention both ends of the cylindrical long-rollers of the cage are in part embraced on their outer surface by part-cylindrical guiding surfaces of recesses in the side plates of the cage, whereby the long rollers are properly, i.e. without obliquity, held by the narrowly guiding surfaces in the recesses. In addition the cage is carried by said guiding surfaces on the outer surface of the long rollers in the roller bearing. During operation of the bearing equipped with said cage, part of the ambient lubricant in the axial bore of the short-rollers becomes centrifugally pushed towards the side ends of the short-rollers and from there it is flung radially outwardly towards the outer surface of the adjacent long rollers. In this way there is effected a continuous distribution of flowing lubricating medium environment, for instance of an oil bath, both to the outer surface of the long rollers and to the guiding surfaces of the recesses of the side plates, which closely slide on this outer surface.  
           [0007]    The cylindrical outer surface of each short-roller can slidingly contact the cylindrical outer surface of the neighboring long-roller, when during operation of the roller bearing a small, constructively defined running play between these two rollers is overcome. After the running through of this play, these two rollers slightly impact each other on their mutual cylindrical outer surfaces, this impact producing an alignment of the short rollers on the long-rollers. The mass inertia forces of the mutual impact are rather small, because the short-rollers have a relatively small mass, which is smaller than the mass of the long-roller.  
           [0008]    Even during long-time operation with high bearing load the magnitude of the running play between the outer surfaces of adjacent long-roller and short-roller does not change, this because of the relatively small mass forces and because of continuous distribution of the lubricating medium into the contacting outer surfaces, which makes the mutual impact and corresponding sliding wear on these surfaces to be of negligible importance.  
           [0009]    The long-rollers of the cage are closely held and slidingly guided in the recesses of the two side-plates, which are positioned against each other by bolts, so that the long-rollers can not fall out of the cage. The central bore of each short roller is passed through axially by one bolt. By this way, each short-roller is held in the non-mounted cage by its bolt and restrained from falling out of the loose cage. The cage of this invention, therefore, forms a self-containing machine element, which can easily be mounted and dismounted, for instance, when the raceways of the roller bearing have to be inspected after a certain running period of the roller bearing.  
           [0010]    Moreover, the cage of this invention has a full complement of rollers, so that an exceptionally high number of rollers per unit raceway length participate to carry the bearing load. This brings about the fact, that a roller bearing, which is equipped with the cage of this invention has a relatively high bearing capacity.  
           [0011]    A second embodiment of this invention has the effect, that there is an extremely and unusually small play between the cylindrical outer surfaces of long-roller and adjacent short-roller in the cage, so that an optimally high number of rollers per unit raceway length is present. The mass forces during the mutual impacts between long-roller and short-roller are concomitantly kept advantageously small because of this very small play.  
           [0012]    In a third embodiment, the long-rollers of the cage has an optimally narrow sliding gap in the pertinent recesses of the side plates at their both ends. This produces the advantage, that each long-roller is freely rotative and, thereby, guided in those recesses without obliquity.  
           [0013]    In a fourth embodiment, both ends of the long-rollers are slidingly contacted and guided by sufficiently wide surface sections of the guiding surfaces of the side plates&#39; recesses. Thereby, an unacceptably high contact pressure force and a corresponding detrimental contact wear on these surface sections is avoided during bearing operation.  
           [0014]    In a fifth embodiment, the solid longrollers take a larger portion of the bearing&#39;s loading than the hollow shortrollers, this because of the higher stiffness and the higher resistance of the long-rollers against radial compression in comparison to the softer hollow shortrollers, the wall of which deflect somewhat during radial compression in the loaded roller bearing.  
           [0015]    In case the load on the roller bearing is increased and the two raceways of the bearing, between which the elastic rollers run, approach each other somewhat, then the loading on the relatively stiff long-rollers become increased more rapidly than the loading on the adjacent, elastically more easily compressible short-rollers. Therefore, during increase of the roller bearing&#39;s load the long-rollers carry a concomitantly growing part of the roller bearing&#39;s load. This feature brings the effect, that the relatively soft short-rollers of the cage having less strength are not becoming overloaded even in case where the roller bearing carries very high bearing loads.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    The self-containing full-complement roller bearing cage according to the invention will now be described in detail by way of example using the following drawings, wherein:  
         [0017]    [0017]FIG. 1 shows a side view of a part of a self-containing fullcomplement bearing for a simple linear roller bearing,  
         [0018]    [0018]FIG. 2 shows a fractionally cut view along the line A-A in FIG. 1,  
         [0019]    [0019]FIG. 3 shows a cross section through part of a modified self-containing full-complement cage for a linear roller bearing having a linear raceway with joining recirculating raceways,  
         [0020]    [0020]FIG. 4 shows a fractionally cut view along the line B-B in FIG. 3,  
         [0021]    [0021]FIG. 5 shows a fractionally cut view along the line C-C in FIG. 4, and  
         [0022]    [0022]FIG. 6 shows a side view of a part of the cage of FIGS. 3, 4 and  5 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    In FIG. 1, 1 designates a full-complement cage, which has in rolling direction  2  alternatively arranged long-rollers  3  having a cylindrical outer surface  4  and short-rollers  5  having a cylindrical outer surface  6 . The outer surface  4  of each long-roller  3  has a diameter D and the outer surface  6  of each short-roller  5  has a diameter D 1 .  
         [0024]    Each short-roller  5  has a central axial bore  7  with a bore diameter D 4 . As commonly known for the function of a simple linear roller bearing the cage  1  moves in rolling direction  2  between a back and forth movable loaded bearing plate  8  having a plane raceway for the rollers  3 ,  5  of the cage  1  and a fixed base plate  9  having a plane counter raceway.  
         [0025]    At the present example the magnitude of the outer diameter D of the long-rollers  3  is exactly the same as the magnitude of the diameter D, of the outer diameter  6  of the short-rollers  5 . Both, the long-rollers  3  and the short-rollers  5  are made out of one and the same elastic material, for example, bearing steel. The long-rollers  3  of the cage  1  are made solid having no central bore. In case of an increase of load on the roller bearing the relatively stiff solid long-rollers  3  take one part of the bearing load which is successively greater than the other part of the bearing load taken by the not so stiff hollow short-rollers  5 . The bore  7  of the hollow short-rollers  5  will become slightly oval due to elastic deformation during high bearing loading.  
         [0026]    The cage  1  has two identically formed plane side plates  10 ,  111 , one on either side of the rollers  3 ,  5 . These two side plates  10 ,  11  are rigidly fixed against each other by rotationally symmetric shafts  14 , these shafts  14  having a cylindrical middle portion  13 , which at the height of the roller center line  12  pass through the bore  7  of the corresponding short-roller  3 . The side plates  10 ,  11  may be manufactured out of a metallic material, for instance brass, or out of a fluorine containing plastic material, which is filled with a solid lubricant, for instance graphite or molybdenumdisulfide.  
         [0027]    Between each shaft  14  and its short-roller  3  there is provided a radial play, the magnitude of which is defined by the difference of the diameter D 4  of the bore  7  of the short roller  3  and the diameter D 3  of the middle portion  13  of the shaft  14 . Each shaft  14  has a center line  15 . The center lines  15  of two in rolling direction  2  neighboring shafts  14  have a mutual distance X which has the same magnitude as the diameter D of the outer surface  4  of the long-rollers  3  plus the diameter D, of the outer surface  6  of the short-rollers  5  plus a certain small mutual running play Y between the outer surface  4  of each long-roller  3  and the outer surface  6  of the adjacent short-roller  5 . In the present example the magnitude of the mutual running play Y is about 4% of the diameter D of the outer surface  4  of the long-roller  3 .  
         [0028]    Each long-roller  3  has two opposite ends  16  and  17  penetrating into a roller guiding holding recess  18  and  19  respectively. The recesses  18  and  19  are formed in adjacent inner surfaces  20  and  21  respectively of corresponding side plates  10  and  11  respectively. Each holding recess  18  and  19  has a pair of opposed, concentric, part-cylindrical guiding surfaces  22  having a common center line  23  normal to the rolling direction  2 . The pair of part-cylindrical guiding surfaces  22  of each holding recess  18  and  19  have a common diameter D 2 , which is slightly greater than the diameter D of the outer surface  4  of the long-roller  3 .  
         [0029]    The outer surface  4  of each roller end  16  and  17  respectively is narrowly held along its circumference by the two guiding surfaces  22  of the corresponding holding recesses  18  and  19  respectively, so that the long-rollers  3  do not fall out of the loose cage  1 . A small guiding play Z is maintained between the outer surface  4  of the long-roller  3  and the guiding surfaces  22  of each holding recess  18  and  19  as a result of the difference between the greater diameter D 2  of the guiding surfaces  22  and the smaller diameter D of the outer diameter  4  of the long-roller  3  (FIG. 2). In the present example the magnitude of the guiding play Z is about 3% of the diameter D of the outer surface  4  of the longroller  3 .  
         [0030]    The two guiding surfaces  22  of each holding recess  18  and  19  comprise a surface section which bears on the outer surface  4  of a corresponding long-roller  3 , this section having a width “t” extending in the direction of the center line  23  of the guiding surfaces  22 . The magnitude of the width “t” is about 20% of outer diameter D of the outer surface  4  of the long-roller  3 .  
         [0031]    The mutual distance X, in the rolling direction  2 , of two center lines  15  of two neighboring shafts  14  has the same magnitude as the mutual distance X 1 , of the center-lines  23  of two neighboring holding recesses  18  and  19  respectively of the two side plates  10  and  11  (FIG. 2). The radial play between the middle portion  13  of each shaft  14  and the bore  7  of a short-roller  5  is greater than the guiding play Z of the ends  16  and  17  of the long-rollers  3  in the corresponding holding recess  18  and  19  respectively plus the mutual running play Y between long-roller  3  and short-roller  5 . As a result, the short-rollers  5  of the cage  1  are put into a non-oblique position merely by their running against a neighboring long-roller  3  during operation in the roller bearing and, thus, they are always guided to roll in the rolling direction properly.  
         [0032]    Every shaft  14  has a reduced portion  24  at either of its ends, which joins the middle portion  13 . Each reduced portion  24  penetrates into a hole  25  in the corresponding side plate  10 ,  11 . The inner surface  20  and  21  respectively of the side plate  10  and  11  respectively rests against a shoulder  26  of each shaft  14 , this shoulder  26  being located at the joint between the middle portion  13  and the corresponding reduced portion  24  of the shaft  14 . As seen in FIG. 2, both reduced portions  24  of each shaft  14  penetrate through a hole  25  formed in the corresponding side plate  10  and  11  respectively from the inside to the outside of the plates  10 ,  11 . The shafts  14  are made from a non-alloyed steel. They have an end portion  29  which protrudes beyond an outer side face  27  and  28  respectively of the corresponding side plate  10  and  11  respectively. This end portion  29  is enlarged by riveting so as to become placed against the corresponding outer side face  27  and  28  respectively of the corresponding side plate  10  and  11  respectively.  
         [0033]    In FIGS. 3, 4 and  5  there is shown a modified self-containing full-complement cage  30 , which has been built symmetrically to a middle plane  31 . This cage  30  is mounted onto a bearing shoe  32  of a linear roller bearing, as can be seen in FIG. 6. The shoe  32  becomes moved linearly back and forth during operation, thereby carrying a bearing load via the cylindrical long-rollers  3  and the cylindrical short-rollers  5  of the cage  30  along a loaded linear plane raceway  33  of the shoe  32  onto a plane counter raceway  34  of a fixed base plate  35 . The long-rollers  3  and the short rollers  5  roll along the linear raceway  33  into one of two half-cylindrical reversing raceways  36 , which are arranged on either end of the bearing shoe  32 . From there they roll into a non-loaded plane linear return raceway  37  of the bearing shoe  32  (FIG. 6).  
         [0034]    Similar to the previous embodiment, the long-rollers  3  and the short-rollers  5  are arranged alternatively one after another in the cage  30  in rolling direction  2 . The long-rollers  3  are also again built solid and the short-rollers  5  have a central cylindrical bore  7 . The cage  30  possesses two side plates, one arranged on either side of the rollers  3 ,  5 . The side plates are also fixed against each other by shafts  14 . Each shaft  14  has a middle portion  13 , which penetrates with radial play through the bore  7  of the corresponding short-roller  5  at the height of the center line  12  of the short-roller  5 . Each long-roller  3  has an end portion  16  and  17  respectively on either side, which enters into a holding recess of an adjacent inner surface  20  and  21  respectively of the corresponding side plate. Each holding recess  18 ,  19  has a pair of opposed part-cylindrical guiding surfaces  22  with a common center line  23 , the center-line  23  normally crossing the rolling direction  2 .  
         [0035]    As seen in FIGS. 3, 4 and  5 , the modified cage  30  has side plates, which are divided into plate links  38  which are arranged in rolling direction  2  in line one after another. Each plate link  38  has an end portion  39  and  40  respectively. The end portions  39 ,  40  of two neighboring plate links  38  overlap each other. At the place of overlapping there is arranged a cylindrical pivot pin  41 . The pivot pin  41  has a center line  42 , which coincides with the center line  23  of the guiding surfaces  22  (FIG. 4).  
         [0036]    Both ends of each pivot pin  41  slidingly penetrate into a cylindrical pivot hole  43  and  44  respectively. The holes  43 ,  44  are arranged in line with each other, whereby the pivot hole  43  is formed in the end portion  40  and the pivot hole  44  is formed in the end portion  39  of the respective link  38 . Thus, two neighboring links  38  are held to freely swivel around the center-line  42  of the common pin  41 . The pins  41  can be manufactured from a wear resistant plastic material, which is filled with a wear reducing solid lubricant. In this case the cage  30  with its links  38  forms an endless chain, which is mounted around the bearing shoe  32 .  
         [0037]    Each shaft  14  passes through the bore  7  of the corresponding short-roller  5 . At both ends of the middle portion  13  of the shaft  14  there is formed a reduced portion  24 , which is rigidly connected to a middle portion  45  of one plate link  38  of the corresponding side plate by riveting.  
         [0038]    The reversing raceway  36  of the bearing shoe  32  has a groove  46 , which extends along the raceway  36  in a recirculating rolling direction. The groove  46 , having a width greater than the length of the short rollers  5 , receives and guides the recirculating short-rollers  5  therein.  
         [0039]    As in the first embodiment described above, there are center-lines  15  of neighboring shafts  14  in the cage  30 , which have a mutual distance X in the rolling direction  2  having the same magnitude as the mutual distance X 1 , in rolling direction  2  of the two center-lines  23  of neighboring recesses  18 ,  19  of the links  38  of the cage  30  (FIG. 4 and  5 ).  
         [0040]    The radial play between the middle portion  13  of each shaft  14  and the bore  7  of the corresponding short-roller  5  is greater than the guiding play Z of the ends  16 ,  17  of the long-rollers in their holding recess  18  and  19  in the links  38  of the corresponding side plate plus a small running play y between the outer surface  4  of each long-roller  3  and the adjacent outer surface  6  of the corresponding short roller  5  (FIG. 3 and  4 ). In this manner the orientation of the short-rollers  5  of the cage  30  is maintained non-obliquely during operation by merely running against a neighboring long-roller  3 .  
         [0041]    Further considerable modifications of the above demonstrated examples are possible within the scope of this invention. For example, both side plates of the cage may be made of one piece and formed circularly, so that the corresponding ring-type cage can be installed into a common rotative cylindrical roller bearing.  
         [0042]    If a certain distribution of load between the long-rollers and the short-rollers, both manufactured from an elastic material, for instance bearing steel, is intended to be obtained, then the diameter D of the long-rollers of the cage can be made somewhat smaller or somewhat greater than the diameter D 1 , of the short-rollers, based on the desired different elastic compressive yielding of the long-rollers during operation.

Technology Category: f