Abstract:
A method for producing a composite rolling bearing ( 1 ) having a bearing flange ( 3 ) and at least one rolling bearing ( 4, 5 ) held on the bearing flange ( 3 ) by an inner ring ( 6, 7 ). In order to be able to fix the inner ring ( 7 ) on the bearing flange ( 3 ) with axial preloading without expansion, the inner ring ( 7 ) is acted upon by a holding-down device ( 23 ) that radially holds down the inner ring ( 7 ) and is preloaded against the inner ring ( 7 ) by a regulated axial force (F), and, by way of an advancing cone ( 21 ) introduced radially on the inside axially into the bearing flange ( 3 ), material ( 11 ) present on the bearing flange ( 3 ) is displaced radially towards the outside into a recessed formation ( 15, 16 ) in the inner ring ( 7 ).

Description:
A method for producing a composite rolling bearing having a bearing flange and at least one rolling bearing held on the bearing flange by means of an inner ring. 
     BACKGROUND 
     Composite rolling bearings of the type in question are used as wheel bearings in motor vehicles, for example, wherein the bearing flange accommodates at least one, preferably two, rolling bearings arranged axially adjacent to one another and having inner rings. In this arrangement, the inner rings are mounted on the bearing flange under an axial preload. DE 10 2008 064 155 A1 discloses a rotary forming method for producing a riveting collar on the bearing flange, in which a riveting collar is obtained from a flange part extending axially along the axis of rotation of the rolling bearings by forming the end face radially. In this process, rollers of a feed cone, which are set at an angle relative to the axis of rotation, form the riveting collar. Compared with conventional riveting involving a rolling action, there is a risk, admittedly reduced but still present, that the adjacent inner ring will be expanded. In the case of inner rings of sufficiently stable design, the overall height disadvantageously requires an increased installation space. The radial forming entails poor control over the axial preloading of the inner ring on the bearing flange. Moreover, the large angles of incidence of the rollers, in particular, lead to relatively high tool wear in the case of high forming forces. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a method for producing a composite rolling bearing in which expansion of the inner ring is avoided and the setting of the axial preload of the inner rings or of the inner ring can be set precisely. 
     The present invention provides a method for producing a composite rolling bearing having a bearing flange and at least one rolling bearing held on the bearing flange by means of an inner ring, wherein the inner ring is acted upon by means of a holding-down means that radially holds down the inner ring and is preloaded against the inner ring by a controlled axial force, and, by way of a feed cone introduced radially on the inside axially into the bearing flange, reserve material on the bearing flange is displaced radially outward into a recessed formation in the inner ring. 
     According to the method proposed, in contrast to the riveting method, material of the bearing flange is not reshaped radially outward but is displaced radially outward in order to produce an axial preload and axial fixing of the single or outer inner ring closer to the end of the bearing flange, wherein the holding-down means stabilizes the inner ring radially toward the outside and can form an axial stop for the displaced material. Here, an axial stop is formed for the inner ring, with the inner ring being axially preloaded by the holding-down means during the material displacement process by the latter being acted upon by a controlled axial force. In this way, displacement or deformation of the inner ring is not possible. At the same time, the axial fixing of the inner ring is accomplished with a constant, adjustable preload. Stabilizing the inner ring by means of the holding-down means during the process enables the inner ring to be given smaller dimensions and, overall, enables the composite rolling bearing to be designed with a smaller installation space and a lower weight since these definitive variables need no longer be designed according to the method but according to requirements during operation. 
     According to an advantageous method, the reserve material is displaced at least partially by the feed cone or by rollers mounted on the feed cone. During this process, the feed cone is rotated and displaced axially with a predetermined feed, wherein the material overhanging radially inward relative to the inner circumference of the bearing flange is displaced radially outward, and a corresponding quantity of material is formed on the outer circumference of the bearing flange and is displaced into radially opposite recessed formations on the inner ring. During this process, the holding-down means, like the bearing flange, is supported in such a way that it does not rotate. 
     In an advantageous embodiment, for example, a material overhang formed radially on the inside on one end of the bearing flange as reserve material can be displaced into a chamfer formed radially on the inside as a recessed formation on one end of the inner ring. During this process, the holding-down means, which is extended radially inward in a corresponding manner, can act as an end-located limiting wall for the displaced material, and the inner ring and the displaced material can be flush at the end. As an alternative, an annular collar of the bearing flange can be formed by setting back the wall provided on the holding-down means axially in a corresponding manner, said annular collar being extended axially relative to the end of the inner ring. 
     The wall can furthermore be provided as a die, e.g. in the form of end toothing, with the result that, given appropriate displacement of material in the end region of the bearing flange, end toothing is formed in the end of the bearing flange, resulting, in the case where the composite rolling bearing is designed as a wheel bearing with a corresponding profiling of a drive shaft, in joining of the bearing flange to the drive shaft for conjoint rotation, requiring only axial clamping of the composite assembly. As an alternative, end toothing of this kind can be introduced into the bearing flange in advance, in which case displacement of material is not envisaged in the region of the end of the bearing flange. As an alternative, the end toothing can be introduced in advance and displacement of material on the end of the bearing flange can be envisaged if the end toothing is protected by a complementarily shaped wall of the holding-down means. 
     As an alternative or in addition, a material overhang formed radially toward the inside can be provided as reserve material on the inner circumference of the bearing flange at an axial distance from the end of the latter, said material being displaced into a recessed formation at an axial distance from one end of the inner ring. The recessed formation can be an annular groove or the like, for example. 
     In order to achieve advantageous centering of the holding-down means on the inner ring and good removal thereof after the method has been carried out, the holding-down means can be centered on a chamfer provided radially on the outside of the at least one inner ring, wherein the holding-down means is of an appropriately conical design in this region. 
     According to an advantageous embodiment, the holding-down means can fit over the inner ring radially on the inside and radially on the outside. 
     The formation of the material overhangs of reserve material makes it possible to keep the forming forces low. In this context, the forming forces can be modified through the forming angle of the rollers on the feed cone. For example, the feed and slope of the rollers can be set in accordance with a radial variation in an axial width of the reserve material. In this case, the axes of rotation of the rollers can be 10° to 20° to the axis of rotation of the inner ring, wherein the rollers can form on the inner circumference a recessed formation region which slopes relative to the substantially cylindrical inner surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in greater detail by means of the illustrative embodiments shown in  FIGS. 1 to 11 , where: 
         FIG. 1  shows an unprocessed form of a composite rolling bearing in partial section, 
         FIG. 2  shows the unprocessed form of  FIG. 1  with the forming tool applied, in partial section, 
         FIG. 3  shows the composite rolling bearing in the finished state in partial section, 
         FIG. 4  shows a composite rolling bearing modified as compared with the composite rolling bearing in  FIGS. 1 to 3 , in the unprocessed form, having end toothing to be formed, in partial section, 
         FIG. 5  shows a partial section of the composite rolling bearing in  FIG. 4  in the finished state, 
         FIG. 6  shows an unprocessed form of a composite rolling bearing with end toothing introduced even before the process of material displacement, in partial section, 
         FIG. 7  shows an unprocessed form of a composite rolling bearing with the holding-down means fitted over the inner ring radially on the inside and outside, in partial section, 
         FIG. 8  shows an unprocessed form of a composite rolling bearing with a material overhang stepped radially toward the outside from the end of the bearing flange, in partial section, 
         FIG. 9  shows an unprocessed form of a composite rolling bearing with material overhangs formed relative to the axis of rotation of the inner ring by steeply angled rollers of the feed cone, in partial section, 
         FIG. 10  shows an unprocessed form of a composite rolling bearing with a wall of the holding-down means which is set back axially relative to an end of the inner ring, in partial section, and 
         FIG. 11  shows a partial section of an unprocessed form of a composite rolling bearing having holding-down means centered conically on the inner ring. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a partial section through the composite rolling bearing  1  in unprocessed form arranged around the axis  2  of rotation. The bearing flange  3  accommodates two rolling bearings  4 ,  5 , which are arranged axially adjacent to one another and the inner rings  6 ,  7  of which are mounted without play, by means of an interference fit, against the axial stop  9 , on the flange part  8  arranged along and around the axis  2  of rotation. 
     The reserve material  11  in the form of the material overhangs  12 ,  13  is extended out of the cylindrical surface  10  radially inward and in a ring over the circumference of the inner circumference of the bearing flange  3 . At the end  14  of the bearing flange  3 , material overhang  12  has a substantially wedge shaped cross section which widens radially in the direction of the end  14 . Material overhang  13  is at an axial distance from the end  14  in the direction of the axial stop  9 . 
     Recessed formations  15 ,  16  complementary to the material overhangs  12 ,  13  are provided in the inner ring  7 , which are off-tool features or are machined into the inner ring  7  subsequently. The ends  14 ,  17  of the bearing flange  3  and of the inner ring  7  are formed axially flush, with the result that recessed formation  15  is formed as an outward-opening chamfer  18 . Recessed formation  16  is designed as an annular groove  19 . 
       FIG. 2  shows the unprocessed form of the composite rolling bearing  1  with the roll-forming tool  20  (shown schematically) applied at the beginning of the roll-forming process, said tool being formed by the feed cone  21  with the rollers  22 , such as forming rollers, mounted rotatably thereon, the holding-down means  23  and the corresponding bearing arrangements (not shown) for the composite rolling bearing  1 , the feed cone  21  and the holding-down means  23  as well as driving and control devices thereof 
     At the beginning of the roll-forming process, the holding-down means  23  is applied to the ends  14 ,  17  of the bearing flange  3  and of the inner ring  7 , with a selected axial force F, which is controlled during the roll-forming process, being input, thus enabling a predetermined preload on the inner rings  6 ,  7  relative to the axial stop  9  of the bearing flange  3  to be set. 
     The holding-down means  23  fits around the outer circumference  24  of the inner ring  7  by means of the shoulder  25 , which is extended axially relative to the end  17  and which can be in the form of a ring or of a ring segment, and thus fixes the inner ring  7  radially on the outer circumference  26  of the flange part  8 , preventing the latter from undergoing any radial expansion in the subsequent roll-forming process. 
     During the roll-forming process, the feed cone  21  with the rollers  22  mounted thereon in an axially fixed manner which allows rotation about the axis  27  of rotation is moved axially, as a result of which the reserve material in the form of the material overhangs  12 ,  13  is rolled radially inward as the rollers  22  rotate, beginning with material overhang  12 . 
     As can be seen from  FIG. 3 , the rolled-in material in the final state of the roll-forming process has displaced material  28 ,  28   a  displaced material from the flange part  8  into the recessed formations  15 ,  16  in the finished composite rolling bearing  1 . In this case, material from the flange part  8  is displaced into the recessed formations  15 ,  16 , with the result that, with a preload being applied to the holding-down means  23 , the inner rings  6 ,  7  are fixed axially on the bearing flange  3  with a constant preload against the axial stop  9 . 
     After the roll-forming process, the surface  10  of the inner circumference of the bearing flange is substantially cylindrical, and the feed cone  21  and the holding-down means  23  are moved back. 
       FIG. 4  shows a variant of a composite rolling bearing  1   a  in unprocessed form with a roll-forming tool  20   a  adapted thereto. Here, the inner ring  7   a  is extended axially relative to the flange part  8   a  of the bearing flange  3   a . The material overhang  12   a  is arranged at the end  14   a  of the flange part  8   a , being extended radially inward. The inner ring  7   a  has a corresponding recessed formation  15   a . The holding-down means  23   a  is designed as a die  30  in the form of axial toothing on its wall  29  facing the end  14   a.    
     At the beginning of the roll-forming process, the holding-down means  23   a  is subjected to the axial force F, and the feed cone  21   a  is moved axially, rotating the rollers  22   a . As a result, the material overhang  12   a  is displaced radially outward, as a result of which displaced material flows out of the flange part  8   a  into the recessed formation  15   a  on the inner ring  7   a . During this process, end toothing is formed on the end  14   a  by the die  30 . 
       FIG. 5  shows the finished composite rolling bearing  1   a  of  FIG. 4  with end toothing  31 , which has been formed in the flange part  8   a  in relation to the ends  14   a  and  17   a  of the flange part  8   a  and of the inner ring  7   a  respectively and can form a connection for conjoint rotation with another component, e.g. a drive shaft in the case of a wheel bearing. 
       FIG. 6  shows another variant of a composite rolling bearing  1   b  having end toothing  31   a  already provided before the roll-forming process. Consequently, only the material overhang  13   b  at an axial distance from the end  14   b  on the flange part  8   b  of the bearing flange  3   b  and a correspondingly oppositely situated recessed formation  16   b  on the inner ring  7   b  are provided. 
       FIG. 7  shows a variant in the form of the composite rolling bearing  1   c , over the inner ring  7   c  of which the holding-down means  23   c  fits from both sides, i.e. radially on the inside and radially on the outside. Here, the wall  29   c  of the holding-down means  23   c  is provided axially with the recess  32  opposite the end  17   c  of the inner ring  7   c , with the result that, after the displacement of the material overhang  12   c , the recessed formation  15   c  is filled with displaced material in such a way that the inner ring  7   c  forms the overhang  33  axially relative to the flange part  8   c  of the bearing flange  3   c.    
       FIG. 8  shows a variant in the form of the composite rolling bearing  1   d  in which the material overhangs  12   d ,  13   d  of the flange part  8   d  of the bearing flange  3   d  merge into one another in a stepped manner. The recessed formations  15   d ,  16   d  are provided radially opposite in a complementary manner on the inner ring  7   d.    
     Whereas the rollers  22  in the preceding figures displace the material overhangs radially outward substantially perpendicularly to the axis  2  of rotation ( FIG. 1 ), a variant of a roll-forming tool  20   d  for displacing the material overhangs  12   d ,  13   d  of the flange part  8   d  of the composite rolling bearing  1   d  of  FIG. 8  is shown in  FIG. 9 . The axes  27   d  of rotation ring  1   d  of  FIG. 8  is shown. The axes  27   d  of rotation of the of the rollers  22   d  accommodated in the feed cone  21   d  have a large angle α of inclination, e.g. between 15° and 25°, relative to the axis  2  of rotation of the composite rolling bearing  1   d , leading to the rollers  22   d  displacing the material overhangs  12   d ,  13   d  obliquely, as a result of which the expenditure of force for displacement of material is lower. In the final state of the roll-forming process, a displacement surface inclined relative to the surface  10   d  of the flange part  8   d  is provided, forming an undercut which can be used for other purposes and on which other components can be snapped or hooked. 
       FIG. 10  shows a variant in the form of a composite rolling bearing  1   e  having ends  14   e ,  17   e  of the flange part  8   e  of the bearing flange  3   e  and of the inner ring  7   e , respectively, which are axially spaced apart, wherein the flange part  8   e  is extended axially relative to the inner ring  7   e . Accordingly, the holding-down means  23   e  is provided with an axially stepped wall  29   e  to form the recessed formation  15   e  and to subject the inner ring  7   e  to the axial force F. 
       FIG. 11  shows a variant in the form of the composite rolling bearing  1   f  in which the inner ring has the centering chamfer  34  on the outer circumference  24   f  thereof for centering the holding-down means  23   f . Accordingly, the holding-down means has the centering cone  35 . 
     LIST OF REFERENCE SIGNS 
     
         
           1  composite rolling bearing 
           1   a  composite rolling bearing 
           1   b  composite rolling bearing 
           1   c  composite rolling bearing 
           1   d  composite rolling bearing 
           1   e  composite rolling bearing 
           1   f  composite rolling bearing 
           2  axis of rotation 
           3  bearing flange 
           3   a  bearing flange 
           3   b  bearing flange 
           3   c  bearing flange 
           3   d  bearing flange 
           3   e  bearing flange 
           4  rolling bearing 
           5  rolling bearing 
           6  inner ring 
           7  inner ring 
           7   a  inner ring 
           7   b  inner ring 
           7   c  inner ring 
           7   d  inner ring 
           7   e  inner ring 
           7   f  inner ring 
           8  flange part 
           8   a  flange part 
           8   b  flange part 
           8   c  flange part 
           8   d  flange part 
           8   e  flange part 
           9  axial stop 
           10  surface 
           10   d  surface 
           11  reserve material 
           12  material overhang 
           12   a  material overhang 
           12   c  material overhang 
           12   d  material overhang 
           13  material overhang 
           13   b  material overhang 
           13   d  material overhang 
           14  end 
           14   a  end 
           14   b  end 
           14   e  end 
           15  recessed formation 
           15   a  recessed formation 
           15   c  recessed formation 
           15   d  recessed formation 
           15   e  recessed formation 
           16  recessed formation 
           16   b  recessed formation 
           16   d  recessed formation 
           17  end 
           17   a  end 
           17   c  end 
           17   e  end 
           18  chamfer 
           19  annular groove 
           20  roll-forming tool 
           20   a  roll-forming tool 
           20   d  roll-forming tool 
           21  feed cone 
           21   a  feed cone 
           21   d  feed cone 
           22  roller 
           22   a  roller 
           22   d  roller 
           23  holding-down means 
           23   a  holding-down means 
           23   c  holding-down means 
           23   e  holding-down means 
           23   f  holding-down means 
           24  outer circumference 
           24   f  outer circumference 
           25  shoulder 
           26  outer circumference 
           27  axis of rotation 
           27   d  axis of rotation 
           28  displaced material 
           28   a  displaced material 
           29  wall 
           29   c  wall 
           29   e  wall 
           30  die 
           31  end toothing 
           31   a  end toothing 
           32  recess 
           33  overhang 
           34  centering chamfer 
           35  centering cone 
         F axial force 
         α angle of inclination