Abstract:
Previously known mechanical deep rolling tools share the feature that their rollers not only roll over the work piece but also over a counter roller on the tool side. This allows the deep rolling roller to swing to the side; but the roller material becomes fatigued relatively quickly. To achieve longer life, a rolling tool is suggested in which a working periphery is located in a work piece contact area spatially separated from a bearing contact area of the roller. A rolling tool with a hydraulically supported forming roller and a roller suitable therefor are also suggested.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of prior filed copending PCT International application no. PCT/DE2004/001860, filed Aug. 20, 2004, which designated the United States and on which priority is claimed under 35 U.S.C. §120, the disclosure of which is hereby incorporated by reference, and which claims the priority of German Patent Application, Serial No. 103 40 267.5, filed Aug. 29, 2003, pursuant to 35 U.S.C. 119(a)-(d), the disclosure of which is incorporated herein by reference.  
         [0002]     This application also claims the benefit of prior filed U.S. provisional Application No. 60/506,749, filed Sep. 29, 2003, pursuant to 35 U.S.C. 119(e), the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0003]     The present invention relates to a rolling tool and a roller for rolling, particularly for deep rolling, a work piece.  
         [0004]     Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.  
         [0005]     The task of designing components that can withstand especially heavy loads is encountered regularly in countless mechanical engineering applications. Indications of premature wear and the associated unexpected failures occur particularly often with dynamically stressed components. The reason for this is often to be found in cracks that begin on the surface of the work piece, particularly on the micronotches or geometric fissures that exist there.  
         [0006]     When used for dynamically stressed components, deep rolling significantly increases fatigue strength. Rolling the work piece causes the edge layer to be deformed. The rolling force used in this process is selected such that the edge layer is rendered plastic during rolling. This is essentially associated with three advantages:  
         [0007]     Firstly, residual internal stresses are created in the edge layer of the component skin, which are also suitable for counteracting tensile stresses that occur otherwise in the edge layer. Secondly, greater resistances are achieved locally with cold forming. Finally, the surface is smoothed microscopically, so that the micronotches, which may lead to cracks are largely eliminated.  
         [0008]     In view of these process-related advantages, of the many mechanical surface treatment processes possible, deep rolling assumes a particular importance. Deep rolling is normally used in the cut-in or the though feed rolling processes. In cut-in processing, profile rollers are used that are specially adjusted to the radius of a fillet to be compacted. They are set up at an angle so that the resulting rolling force is directed at the zone in which the highest material fatigue is to be expected. The deep rolling rollers are suspended in pendulum manner such that the inclination of the rollers may be adjusted automatically to the actual local angle of the surface when they are set against the fillet. In this way, working tolerances are compensated, while assuring the desired distribution of compression stresses in the fillet. This is exceptionally important for assuring the effectiveness of the process.  
         [0009]     The process usually extends over several revolutions of the work piece. The rolling force is gradually increased over a given number of revolutions, then kept constant, and finally reduced again over a further predetermined number of revolutions. The soft engagement/disengagement of the roller avoids sharp stress increases and the additional notching effects that necessarily accompany such.  
         [0010]     While the infeed process is suitable only for narrowly defined areas, preferably for fillets with radii smaller than 4 mm, the throughfeed process is provided for processing larger surfaces.  
         [0011]     In conventional use, no special machinery is required for rolling; instead, the rolling tool may simply be integrated in the existing machine, for example a lathe.  
         [0012]     When deep rolling, the tools are loaded with very high rolling forces. During the rolling process, the roller is pressed against the work piece to be compacted with a defined force and is moved relative thereto. In order to transfer the rolling force to the roller and, at the same time ensure a certain pendulum capability of the roller, the working periphery of the roller runs along the work piece on the work piece side and along a counter roller on the tool side. The pendulum motion is essential for an even distribution of stress in the radius.  
         [0013]     In operation, the roller is thus necessarily rolled twice per revolution. This causes the material to fatigue relatively quickly, particularly given the very high deep rolling forces applied. A low-wearing arrangement is known from European Patent EP 0 353 376 A1. Here, a rolling tool is suggested in which the support is assured hydrostatically. However, the rolling body in this case is spherical and this neat solution does not lend itself to use with form rollers because the sealing edge along a roller contour is much more complex than the sealing edge along a spherical body. With hydrostatically supported rollers, the seal gap would vary so much, even with small—inevitable—pendulum motions, that the essential hydrostatic pressure could not be assured. Moreover, even minor surface damage in the work area of the roller would cause defects in the gap seal.  
         [0014]     Similar or species-related rolling tools are also known from German Patents DE 43 09 176 C2 and DE 33 90 141 C2, and from U.S. Pat. No. 4,821,388 and U.S. Pat. No. 3,945,098.  
         [0015]     It would therefore be desirable and advantageous to provide an improved rolling tool to obviate prior art shortcomings and to cause little wear for a roller.  
       SUMMARY OF THE INVENTION  
       [0016]     According to one aspect of the present invention, a rolling tool includes a roller for rolling, particularly deep rolling, a work piece, the working periphery of the roller running rotatingly along the work piece when the working periphery is located in a work piece contact area of the roller that is separated from the bearing contact area.  
         [0017]     The working periphery is understood to mean the narrow or wider strip along the outer periphery of the roller that transfers the rolling forces to the area of the work piece for compaction during rolling. In microscopic terms, in cases of doubt this is will be two or more strips; macroscopically, this is usually a rotationally symmetrical strip from less than 1 mm to about 8 mm wide that encircles the roller. Although only a small part of the roller&#39;s working periphery is in contact with the work piece at any given time, the roller is moved so that it rolls over the area to be compacted. This is effected by applying a constant pressure to either the work piece or the tool so that the two are pressed against one another. Normally in such cases, the working periphery is exactly rotationally symmetrical, so that a constant radial force is transferred from the roller to the work piece during rotation.  
         [0018]     The term “areas”, refers primarily to the surface of the roller, that is to say particularly the bearing contact area and the work piece contact area. As soon as the rolling force is applied to the roller via the surface of the roller in the bearing contact area and then transferred as deep rolling force from the roller via that part of its surface which is in contact with the work piece, and as long as these loaded surface sections on the roller do not overlap, the reduced load on the rolling material according to the invention is present. For design reasons, this is achieved most simply if the bearing contact area and the work piece contact area are offset with respect to one another, that is to say that the two contact areas do not overlap when the bearing contact area and the and the work piece contact are projected onto the axis of rotation of the roller.  
         [0019]     This creates a configuration in which the roller is supported in a bearing area that is does not include the working periphery. As a result the degree of wear caused directly to the roller is minor.  
         [0020]     The solution for reducing wear according to the invention is suitable for mechanically supported and hydrostatically supported rollers.  
         [0021]     In a preferred embodiment of the rolling tool according to the invention, the bearing contact area is arranged on both sides of the work piece contact area. With a bearing arrangement of such kind, relatively small bearing forces are needed. Whereas with a single-sided bearing cantilever moments would have to be removed via a clamped support, in this way essentially simple compressive forces may be transferred between the bearing and the roller. It is particularly advantageous to ensure that the bearing is symmetrical.  
         [0022]     The bearing may advantageously have a circular arc shaped contour in the bearing contact area. This is understood to mean that in a cross-section through the bearing surface the delimitation of the roller is arced in shape and with this shape preferably lies flush on the bearing. The cross-section through the bearing surface is preferably selected such that the plane of the cross-section is perpendicular to a plane of the working periphery and/or the plane of the bearing contact surface and parallel to the primary direction of pressure of the tool (see the intersecting plane chosen in  FIG. 1  of the drawing). Upon rotation about the roller&#39;s axis of rotation, the arc segment forms a rotational solid, wherein the distance between the roller&#39;s axis of rotation and the arc segment does not have to be the radius of the circle arc. Simply providing it with a circle arc-shaped contour results in a particularly low-wearing, planar bearing. It may also be sufficient if the roller is furnished with such a circular point contour on only one side of the work piece contact area.  
         [0023]     However, it is particularly suggested that the bearing contact area be provided with a bearing contour of a continuous arc in a circular arc shape on both sides of the work piece contact area, the centre point of the continuous arc being in the plane of the work piece contact area. In such a configuration, the roller lies on top of two bearing surfaces on the support; in a cross-section through the bearing however, the bearing surfaces are shown to be shaped such that an arc may be drawn through both bearing surfaces. The bearing surfaces are symmetrical about the centre of the roller, the centre point of the arc passing through the two bearing surfaces thus lies on an imaginary plane of the work piece contact area or the working periphery. The plane is normal with the axis of rotation of the roller.  
         [0024]     In this configuration the roller may be pivoted at least to some degree, thus it may skew the angle of the working plane while the working periphery is rotating without the need to change the roller&#39;s bearing surface on the bearing.  
         [0025]     If in such a configuration not only tangents with the roller, but also a tangent in the work piece contact area perpendicular to a line from there to the centre point of the circle described are in the work piece contact area, a rolling force that is applied to the roller via the working periphery does not produce an undesired distortion of the roller.  
         [0026]     As a special form of bearing with circle arc-shaped contour, it is suggested that the roller have a barrel shape in the bearing contact area. A barrel is characterized in that its curved surface is the rotational solid of a circle arc segment, but that the centre point of the circle arc does not lie on the axis of rotation of the curved surface, which in the case of a roller is the roller&#39;s axis of rotation. It is even advantageous if the centre point of the circle defining the contour of the barrel-shaped bearing contact surface is located in the plane of the working periphery but outside of the roller. This is also associated with the situation in which the radius of the circle defining the barrel shape is a certain amount larger than the radius of the working periphery. In this arrangement, the roller is supported securely under static conditions. A bearing of this type is even suitable for infeed deep rolling operations with cylindrical work pieces or with large-radius contours.  
         [0027]     A barrel-shaped roller in the bearing contact area may be accessed particularly by a mechanical bearing on the tool side, preferably via support rollers such as roller bearings, particularly ball bearings, needle bearings and cylinder roller bearings.  
         [0028]     In a particularly preferred arrangement, the roller may have a spherical shape in the bearing contact area. In this case, the centre point of a circle defining the circle arc-shaped bearing surfaces is coincident with the roller&#39;s axis of rotation. When rotated about the roller&#39;s axis of rotation, the bearing surface yields a strip between each of two lines of longitude on the sphere shape. Suitable spherical shapes are for instance spherical caps or spherical segments that are adjoined laterally to the work piece contact area.  
         [0029]     A roller with a spherical bearing of such shape is advantageous in that it may be pivoted absolutely neutrally and economically in terms of space.  
         [0030]     The spherical shape even renders this roller accessible to a hydraulic, particularly hydrostatic bearing on the tool side to accommodate the roller. This enables the rolling force to be kept extremely constant, thereby assuring high quality and reproducibility of the rolling operation. Support is finally assured with the geometrically relatively simple form of a sphere and is thus independent of the conformation in the work piece contact area.  
         [0031]     The roller may thus pivot particularly easily on a locally present angle of a fillet. In order to ensure that the forces, particularly the hydrostatic forces, are kept constant during such a pivoting operation, it is suggested to provide a pivot bearing area on the roller to preserve the bearing surface when the roller is pivoted. This may particularly be a circle arc contour on the roller that extends beyond the limits of the bearing surface on the tool side. When the roller is pivoted outwards, the roller&#39;s bearing support shifts automatically relative to the bearing on the tool side. As a result, the bearing on the tool side then forces at least a part of the original contact surface downwards. If the geometry of the original bearing area is continued in the manner suggested beside the original bearing surface, the bearing surfaces and the force and stress ratios remain constant in the bearing of the roller.  
         [0032]     It should be noted that a hydraulic, particularly hydrostatic bearing on the tool side to accommodate the forming roller—particularly in conjunction with a pivot bearing area on the roller—is also advantageous and inventive independently of the features of the present invention that are described in the preceding.  
         [0033]     As part of the underlying inventive step, the object presented also suggests a solution for a rolling tool having a hydraulically supported roller for rolling, particularly deep rolling a work piece if the roller is supported on a spherical, but even aspherical, and particularly partially spherical bearing. This directly provides the advantages described, in that a hydraulic bearing with the associated simple controllability of the compressive force may be achieved via the geometrically adjustable spherical bearing, and at the same time the working periphery may be varied from this shape, and in particular modified to match the fillet to be processed.  
         [0034]     Accordingly, a particular aspect of the invention consists in that the prior art is enhanced by a rolling tool having a hydraulically supported forming roller for rolling a work piece.  
         [0035]     For all hydraulic bearings on two sections of a bearing contact area separated by a work piece contact area, it is further suggested that two hydraulic supply lines be provided on the tool side. This particularly has the advantage that the hydraulic bearing pressure on each side of the work piece contact area is assured independently of the other side.  
         [0036]     It should be noted that a roller for rolling, particularly deep rolling a work piece, wherein the roller includes an essentially disc-shaped work piece contact element arranged symmetrically about a roller axis is also advantageous and inventive per se if it is distinguished by bearing elements that are arranged longitudinally relative to the roller axis and rotationally symmetrically about the same axis. In this form it is directly germane to the application according to the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0037]     Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:  
         [0038]      FIG. 1  is a cross-section of a tool head having a roller cradle and a roller cradled on a hydrostatic bearing;  
         [0039]      FIG. 2  is a diagram of a roller having a barrel-shaped bearing element in a central position;  
         [0040]      FIG. 3  is the roller of  FIG. 2  in an outwardly pivoted position;  
         [0041]      FIG. 4  is a diagram of a roller having a spherical bearing element in a central position;  
         [0042]      FIG. 5  is the roller of  FIG. 4  in an outwardly pivoted position;  
         [0043]      FIG. 6  shows a cross-section of a part of a deep rolling tool having a roller cradle and two deep rolling rollers supported therein by hydrostatic means;  
         [0044]      FIG. 7  shows the roller cradle of  FIG. 6 , in which a deep rolling roller has been removed and the sealing geometry for roller in empty chamber thereof is shown diagrammatically;  
         [0045]      FIG. 8  shows a view below empty roller chamber, taken along line VIII-VIII in  FIG. 7 ,  
         [0046]      FIG. 9  shows a cross-section of a variant for a tool according to the invention with two hollow cantilevered rollers and  
         [0047]      FIGS. 10, 11 ,  12  show a tool or the rollers thereof according to the prior art for deep rolling crankshaft splines. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0048]     Throughout all the Figures, same or corresponding elements are generally indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.  
         [0049]     Rolling tool  1  in  FIG. 1  essentially includes a roller cradle  2  and a roller  3 . Roller  3  is supported by hydraulic bearings in roller cradle  2 . For this, two hydraulic bearing pockets  4 ,  5  are used, which are supplied with a liquid during operation via a hydraulic feed system  6  in roller cradle  2 . The liquid is forced on the tool side via a feed chamber  7  into roller cradle  2 ; pressure is also controlled here, since hydraulic feed system  6  is made up of interconnected pipes.  
         [0050]     Roller  3  includes a rolling member  8  and two spherical bearing elements  9 ,  10 , which have the form of spherical caps and are arranged on either side of disc-shaped rolling member  8 . Roller  3  may be produced as a single unit or may incorporate the rolling member and the spherical caps as three separate parts.  
         [0051]     When in operation, bearing area  11  (shown shaded on one side only of roller  3 , but also present symmetrically on the other side) of roller  3  rests on a fluid pressure cushion in pockets  4  and  5 . Rolling forces that are exerted on a work piece  13  along a pressure direction  12  are transferred from bearing contact surface  11  and roller cradle  2  to a connection  7  on the tool side by the pressure cushion in pockets  4 ,  5 . Thus the rolling pressure between tool  1  and work piece  13  may be kept extremely constant.  
         [0052]     A pivot assembly  14  is provided in roller cradle  2  on both sides of disc-shaped rolling member  8 , so that rolling member  8  with a working periphery  15  may be pivoted outwards into a fillet  17  located outside of a central position  16 . In this context, bearing members  9 ,  10  rotate in pockets  4 ,  5  until the roller reaches its outwardly pivoted position in fillet  17 . The angular momentum applied by roller  3  to counteract this torsion of its axis of rotation is normally negligible compared with the high pivoting forces generated by the high rolling force.  
         [0053]     Working periphery  15  is formed by the strip-shaped area that is connected with fillet  17  of work piece  13  when roller  3  rolls along the length thereof. In the embodiment shown, the work piece contact area is rather narrower—relative to an axis of rotation  18  of roller  3 —than disc-shaped rolling member  8 . Bearing contact area  11  is arranged symmetrically on both sides of the work piece contact area and at a certain distance from the rolling member. Extended pivot bearing areas  19 ,  20  and the spherical shape thereof attached to bearing contact area  11  serve to alter a bearing surface  21  (shown on one side only of roller  3 ) and thus not the size of the bearing contact area. To this extent, the ratio of forces is also unaffected.  
         [0054]     Advantageously and in keeping with the basic inventive concept, the geometry of the working periphery or the work piece contact area on the roller is determined by the geometry of the work piece; at the same time, however, the roller bearing on the tool side and thus also the force application is provided via a bearing contact area that is separate therefrom. The bearing contact area is made up of spherical caps or spherical zones on both sides of the work piece contact area.  
         [0055]     The centre point of the sphere is situated on central axis  16  and on axis of rotation  18 . In this way, the roller may be supported either hydrostatically or mechanically by means of a counter roller. In any case, it is assured that the roller may be pivoted outwards about the centre point of the sphere to lie flush with an eccentrically positioned radius for rolling without causing blockages or changes to the seal gap. Moreover, the functions of support and force application are no longer impaired by damage to the roller.  
         [0056]     A tool variant that may also be used in the infeed process includes an axial bearing on the tool side on both end faces of the roller. This bearing may be provided either mechanically or via ball, needle or cylindrical roller bearings. However, for the conditions cited, it is advantageous if the axial bearing is also of hydrostatic type. This applies particularly if the bearing for the rollers is hydrostatic.  
         [0057]     Roller  30  in  FIG. 2  also includes a roughly disc-shaped rolling member  31 , which defines the maximum width of the work piece contact area, and barrel-shaped bearing members  32 ,  33  arranged on either side on rolling member  31 . In the cross-section shown, a bearing contact surface  34  (indicated on only one side of roller  31 ) is formed by a segment  35  of a circle arc about a first centre point  36 . Like the entire roller  30 , the bearing members are arranged rotationally symmetrically about an axis of rotation  37 , thereby creating a second centre point  38  in the cross-section shown, about which the surface of bearing contact area  40  not currently resting flush on a bearing  39  is drawn in an arc. Centre points  36 ,  38  lie on a central axis  41 , which is also situated in the plane of the working periphery.  
         [0058]     The bearing with the circle arc-shaped cross-section enables roller  30  to pivot outwards about centre point  36  that is offset from the bearing. Roller  30  in  FIG. 3  has completed such a pivoting motion. It has shifted with its barrel-shaped bearing members  32 ,  33  tangentially along bearing surfaces  42 ,  43  on the tool side, but still rests on new bearing contact area  44  exactly as wide as bearing contact area  40  of  FIG. 2 , unless it is shifted beyond a swivel bearing range  45 .  
         [0059]     Since the common centre point of the barrel-shaped bearing areas is located outside roller  31 , the roller is supported securely for static purposes. The bearing shown is thus suitable even for infeed deep rolling operations with work pieces that are cylindrical or have large radii. Mechanical force transfer bearings are suitable for use as bearings on the tool side.  
         [0060]     Roller  50  in  FIG. 4  essentially includes a disc-shaped roller  51  and two spherical caps  52 ,  53  for supporting roller  50 . Since a centre point  54  of spherical caps  52 ,  53  is located on an axis of rotation  55  of roller  50 , this may be moved easily about centre point  54  through a pivot angle  56  (shown in  FIG. 5 ) without changing the bearing ratios. A bearing of such kind is suitable for both mechanical and hydraulic force application. Even in the fully pivoted position, as indicated in the roller  50  shown, a bearing contact area  57 ,  58  remains entirely separate from a work piece contact area  59 .  
         [0061]     The versatility of the invention is also shown by a deep rolling roller, a deep rolling tool and a method for deep rolling a surface fillet of a work piece.  
         [0062]     A description of an exemplary application follows with reference to  FIGS. 6, 7 ,  8  and  9 .  FIG. 6  shows a cross-section of a part of a deep rolling tool having a roller cradle  106  and two deep rolling rollers  101 ,  124  supported therein by hydrostatic means.  FIG. 7  shows roller cradle  106  of  FIG. 6 , in which deep rolling roller  124  has been removed and the sealing geometry for roller  124  in empty chamber  126  thereof is shown diagrammatically.  FIG. 8  shows a view below empty roller chamber  126  along line VIII-VIII in  FIG. 7 .  FIG. 9  shows a cross-section of a variant for a tool according to the invention with two hollow cantilevered rollers.  FIGS. 10, 11  and  12  show a tool or the rollers thereof according to the prior art for deep rolling crankshaft splines.  
         [0063]     The objective in this exemplary application is to fixed roll fillets on parts  130  subject to high dynamic loads. These may be rotationally symmetrical parts  130  with a diameter  132  and a shoulder  131 . These be rotationally symmetrical components may be delimited by a similar shoulder  133  on the opposite side. This arrangement is found chiefly in crankshafts, wherein the diameter  132  may be a crank pin or a bearing pin.  
         [0064]     The production tolerances applied for crankshafts mean that shoulders  131 ,  133  may be located in axially offset positions  131 ′,  131 ″;  133 ′,  133 ″. However, deep rolling can only be performed optimally if roller radius  102  is in full surface contact with fillet  102 ′ of the work piece. Since dimensional deviations occasionally occur in work pieces, the deep rolling rollers must be capable of adjusting to the actual position of the shoulders every time they are used.  
         [0065]     Previous mechanical systems as shown in  FIG. 10  operate with deep rolling rollers  140 , which are pressed against work piece radii  144  by thrust rings  141 . To achieve this, forces  142  are applied to the rollers opposite the processing points. This application of force generates strong Hertz compression in both the thrust rings and the rollers. Together with the Hertz compression at the processing points  144 , which is also high, this loading shortens the service life of the deep rolling rollers. The mechanical arrangement also provides for a pivoting motion  143  to compensate for production tolerances. However, this pivoting motion takes place about the centre points of the radius  144 .  
         [0066]     Previous hydrostatic systems such as those shown in  FIGS. 11 and 12  avoided stressing the rollers with the mechanical application of force. However, the pivoting motion about centre of rotation  150  necessary for this variant too cause the deep rolling rollers to shift position in the roller cradle. This misalignment caused profile distortions of almost 0.2 mm. This altered the gap insulation to an unacceptable degree. This led to excessive leakage and caused the system to function unreliably.  
         [0067]     The use of a hydrostatic bearing for a deep rolling roller and an automatic replenishment system in conjunction with such a tool is known from European Patent EP 0 353 376 B1. An important property of hydrostatic bearings is the gap insulation between the roller and the roller cradle. According to this, during operation a certain quantity of pressure fluid escapes constantly along sealing line  113 ,  114 ,  115 . This allows the deep rolling roller  101  to rotate without contact and thus also without friction. The fluid that escapes through the seal gap must be substantially less than the maximum quantity that can be supplied by the force pump through connector hole  127 . If this is not the case, the fluid pressure in pressure chamber  126  falls and rolling force F is reduced. This is not acceptable. The following system  106 ′ responds to an upward movement  125  that enlarges the seal gap slightly when the position of the roller cradle changes relative to the roller. If the pressure in chamber  126  is too low, the roller cradle is lowered slightly in direction  125 ′ by the following system, so that the circumferential seal gap is narrowed and the fluid pressure increases again.  
         [0068]     Even with an automatic following system and a hydraulic bearing for a deep rolling roller, it has not been possible until now to achieve optimum results for rolling grooves with varying dimensions in a work piece using known methods. The present invention is also represents a solution to the task underlying the use that will now be described in detail, that of providing a tool which is able to assure optimum surface treatment by economical means.  
         [0069]     The object according to this aspect of the invention is solved with a deep rolling roller, a deep rolling tool and a method for deep rolling as illustrated by the two embodiments in FIGS.  6  to  9  and the following description:  
         [0070]     The deep rolling rollers according to the present invention are capable of adapting to match the actual positions of the shoulders at each use. For this purpose, the deep rolling rollers according to  FIG. 6  and  FIG. 9  are mounted on the roller cradles in such manner that they are able to be pivoted about centreline  104 ′. Moreover, the deep rolling rollers are also rotatable about their own centrelines  101 ′. Both movements may be performed simultaneously. As the rolling process continues, a plastic deformation takes place in the area of radius  102 . Rolling force F must remains constant throughout the entire process. This is assured by the fact that the deep rolling rollers may be pivoted further even during the process with rotation in an arced direction  125  about centreline  104 ′. In the case of crankshafts, it is helpful to install a second, symmetrically arranged deep rolling roller  124  to process both fillets at the same time. This arrangement has the further advantage that horizontally acting forces F act in opposing directions and thus cancel each other out. Neither the work piece nor the tool is exposed to horizontal forces. A setup of this kind is illustrated in  FIG. 6 .  
         [0071]     The following features of a hydrostatic deep rolling roller  101  with radii  102  or another profile corresponding to the work piece contour are highlighted particularly in FIGS.  6  to  8 : 
        At least one spherical delimiting surface  103  (rounded end with radius  9 )     Centreline  104  of the rounded end is located on centreline  104 ′, centreline  104 ′ forming the cylindrical axis of the convexity on sealing surface  107 . Sealing surface  107  seals chamber  126  along the planar lateral surface  105  of roller  101  except for a hydraulic escape gap.     Plan surface  105      Roller cradle  106  with seal gap  107 , conformed cylindrically aligned on centreline  104 ′, provided with radius  108 .     Cylindrical shape of sealing surface  110  with radius  109 , also aligned on centreline  104 .     Recesses in the roller cradle furnished with radius zones  102 ′, connecting sealing surfaces  110  and  107 . Radius zones  102 ′ extend in an arc corresponding to centreline  111  at a distance from radius  112  of centreline  104 ′.     Roller cradle and roller form a hydrostatic seal gap in the area of contact lines  113 ,  114 ,  115 .     Roller cradle connected with hydrostatic following system  106 ′ as described in European Patent EP 0 353 376 and corresponding national and international patents of this patent family.     When the tool is in the rest position, spring elements  126  pivot the deep rolling rollers back to a point so that the rollers cannot collide with the work piece as the processing point approaches or recedes.        
 
         [0081]     Features of an alternative configuration ( FIG. 9 ) are largely similar to those of a hydrostatic roller as described above, but with the following features: 
        Concave spherical surface  120 , conformed with radius  121  relative to centre point  104 .     Roller cradle  123  conformed with convex spherical or approximately spherical surface  122 , also with radius  121  relative to centre point  104 .        
 
         [0084]     Particularly with reference to the concrete, second task described, the following solutions are therefore also claimed as falling within the scope of the present invention: 
        a) A deep rolling roller having a rolling area and two lateral areas, wherein when the roller is in use the rolling area is intended to run rotatingly along a work piece, wherein the deep rolling roller is characterized in that it has an at least approximately spherical shape in one lateral area and the opposing lateral area is at least approximately flat.     b) A deep rolling roller having a rolling area and two lateral areas, wherein when the roller is in use the rolling area is intended to run rotatingly along a work piece, and which is characterized in that the deep rolling roller is rotationally symmetrical about a rolling axis, but at the same time has mirrored symmetry with respect to all planes that are perpendicular to the rolling axis.     c) A deep rolling roller having a rolling area and two lateral areas, wherein when the roller is in use the rolling area is intended to run rotatingly along a work piece, and which is characterized by a similarly designed, at least approximately spherical curvature of both lateral areas of the deep rolling roller.     d) A hydrostatic deep rolling roller tool having a roller particularly according to one of solutions (a), (b) or (c), wherein the tool is equipped with a roller cradle with a chamber to accommodate and guide the deep rolling roller, and which is characterized in that the chamber has a roller aperture and/or an cross-section aligned at least approximately parallel therewith, and which extends lengthwise essentially between two radius zones, a first delimitation having a convex curvature and the opposite delimitation having a concave curvature or at least being approximately straight.     e) A hydrostatic deep rolling roller tool having a roller particularly according to one of solutions (a) to (c), wherein the tool is equipped with a roller cradle having a chamber to accommodate and guide the roller and which is characterized by a convexity having an at least approximately cylindrical curved surface shape on an outer wall of the chamber, wherein one opposing sealing wall of the chamber is preferably conformed spherically, wherein a centre point of the spherical shape is on an axis of the cylinder. Alternatively, the outer sealing wall may also be spherical in shape, in which case the centre points of both spheres are superimposed on one another.     f) A method for deep rolling particularly a surface channel of a work piece, preferably with a deep rolling roller according to one of the solutions (a) to (c) and/or a tool according to one of solutions (d) or (e), and which is characterized in that a deep rolling roller is subjected to hydrostatic pressure between two sealing walls in a roller cradle, which pressure exerts a deep rolling force on the work piece with an escape through a seal gap extending circumferentially around the roller, wherein the roller shifts out of a chamber in a roller cradle due to the hydrostatic load until equilibrium of the roller is established between fluid loading and work piece, wherein the roller performs a pivoting movement when moving out of the chamber on its path to the work piece surface.        
 
         [0091]     While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.