Abstract:
A system for assembling a vehicle drive shaft is provided with the steps of installing yokes on respective ends of a drive shaft tube, each yoke having first and second bores therethrough for receiving respective distal ends of respective spider arrangements, and rolling the outer edges of the bores using carbide rollers to urge a portion of the material of the yoke to overlie radially the respectively associated distal end of the spider arrangement. Datums are defined on the yokes and the shaft tube for determining a spatial relationship between the yokes and shaft tube. The rolling of the bore of the yoke is performed while the spider, the bearing caps, and the retention elements are maintained in preload to achieve zero tolerance. Prior to roller forming the outer edge of the bore, the spider arrangement is supported on the true rotating center of the drive shaft tube.

Description:
RELATIONSHIP TO OTHER APPLICATION(S)  
       [0001]    This application claims the benefit of the filing date of U.S. Provisional Patent Application Serial Nos. 60/313,741; 60/313,734; and 60/313,739; all of which were filed on Aug. 20, 2001 in the names of the same inventors as herein. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to systems for assembling shafts, such as drive shafts for motor vehicles, and more particularly, to a system that facilitates assembly of shaft components at flexible couplings, such as via Cardan joints, while maintaining a true running center axis for the flexible components at both ends of the shaft.  
           [0004]    2. Description of the Related Art  
           [0005]    Cardan joints, also known as Hooke&#39;s joints, are well-known simple universal joints that consist of two yokes that are attached to respective shafts and connected by means of a spider. The spider is a cross-axis element that accommodates the yokes of the two respective shafts at its respective distal ends. It is evident that this simple structure can be difficult to align during assembly. This problem is compounded by the fact that the spider often is installed in a yoke with a roller bearing arrangement interposed therebetween. In addition to the tolerances that are accumulated during manufacture of the yokes and the spider, it readily can be seen that the spider is axially displaceable within the each of the yokes.  
           [0006]    It is additionally well known that the conventional Cardan joint is not a constant velocity drive element, and therefore, vibration and noise are increased if the articulation torque required to flex the joint about one axis of the spider differs greatly from the torque required to flex the joint about the other axis.  
           [0007]    Conventional assembly processes include, for example, the fitting by hand of retained clips into grooves that are precut into the inner surface of the aperture of the yoke that accommodates the spider. As a result of typical assembly tolerances between the location of the groove, the thickness of the retaining clips, and the dimensions of the bearing cap, the known process of assembly permits the spider to move axially in each yoke during its life. The resulting instability causes imbalance and noise, vibration, and harshness (“NVH”). The prior art has endeavored to address these problems by using, for example, thermal-set glues and fillers on the drive shaft bearing retainers. This known approach is possessed of all of the problems associated with the retaining clips, and renders servicing of the joint difficult.  
           [0008]    It is, therefore, an object of this invention to provide a system for assembling the drive shafts of motor vehicles wherein the flexible components are maintained during assembly on the true vehicle running center axis.  
           [0009]    It is another object of this invention to provide a system for assembling drive shafts of motor vehicles wherein a consistent and uniform pre-load force is applied to the bearing ends to produce consistent articulation torque.  
           [0010]    It is also an object of this invention to provide a system for assembling drive shafts for motor vehicles wherein the joints can easily serviced using conventional tools and conventional retaining clips.  
           [0011]    It is a further object of this invention to provide a system for assembling the drive shafts of motor vehicles wherein manufacturing tolerances in the axial length of the spider, the thickness of the bearing end cap, the thickness of the retaining clip, and the axial dimension of the yoke are accommodated during assembly.  
         SUMMARY OF THE INVENTION  
         [0012]    The foregoing and other objects are achieved by this invention which provides, in accordance with a first aspect thereof, a system for assembling a vehicle drive shaft.  
           [0013]    The system is provided with the steps of:  
           [0014]    first installing a yoke on a first end of a drive shaft tube, the yoke having first and second bores therethrough for receiving respective distal ends of a spider arrangement; and  
           [0015]    rolling an outer edge of the first bore to urge a portion of the material of the yoke to overlie radially the respectively associated distal end of the spider arrangement.  
           [0016]    In a highly advantageous embodiment of the invention, the rolling of the outer edge of the first bore is achieved using a carbide roller arrangement.  
           [0017]    Further in accordance with the invention, prior to performing the step of first installing a yoke, there is provided the further step of defining a datum on the yoke. The datum corresponds, in a specific illustrative embodiment of the invention, to a machined surface of the yoke, which may be a substantially cylindrical surface parallel to the axis of rotation of the yoke. There is provided the further step of defining a datum on the drive shaft tube. In a specific illustrative embodiment of the invention, the datum on the drive shaft tube corresponds to a cylindrical outer surface of the drive shaft tube. The yoke is installed on the drive shaft tube in conformance with a spatial relationship with respect to one another that is responsive to their respective datums. Such installation includes the step of supporting the yoke and the drive shaft tube, which includes the further step of clamping the drive shaft tube. Such clamping urges the drive shaft tube to a condition of increased cross-sectional roundness. In a highly advantageous embodiment of the invention, the spatial relationship is coaxial within 0.006 inches, and preferably within 0.004 inches.  
           [0018]    In one embodiment of this system aspect of the invention, prior to performing the step of turning the outer edge of the first bore there is provided the further step of second installing a fastening ring in the first bore radially overlying of the respectively associated distal end of the spider arrangement, and the step of roller forming the outer edge of the first bore to urge the portion of the material of the yoke to overlie the fastening ring. In addition, prior to performing the step of roller forming the outer edge of the first bore there is provided the further step of third installing a bearing cap in the first bore for supporting rotatively within the first bore the respectively associated distal end of the spider arrangement.  
           [0019]    In a further embodiment of the invention, there are provided the further steps of:  
           [0020]    second installing a further yoke on a second end of a drive shaft tube, the further yoke having first and second bores therethrough for receiving respective second distal ends of the spider arrangement, the second distal ends being arranged orthogonal to the respective distal ends; and  
           [0021]    roller forming an outer edge of the first bore of the further yoke to urge a portion of the material of the further yoke to overlie radially the respectively associated second distal end of the spider arrangement.  
           [0022]    Prior to performing the step of second installing a further yoke on the second end of the drive shaft tube there are provided the further steps of defining a datum on the further yoke and a further datum on the second end of the drive shaft tube.  
           [0023]    Prior to performing the step of roller forming the outer edge of the first bore there is provided the further step of supporting the spider arrangement in a position corresponding to the true rotating center of the drive shaft tube. The step of supporting the spider arrangement includes the further steps of:  
           [0024]    first applying a first supporting force radially inward and coaxially parallel with the respectively associated distal end of the spider arrangement; and  
           [0025]    second applying a second supporting force radially inward and coaxially parallel with the axially opposing end of the spider arrangement, the steps of first and second applying being performed simultaneously, whereby the spider arrangement is supported to maintain its axial position.  
           [0026]    In a still further embodiment, there is provided the step of first clamping the drive shaft tube at the first end thereof so as to be immovable with respect to the supported axial position of the spider arrangement. Simultaneously with the step of first clamping the drive shaft tube there is performed the further step of controlling the first clamping of the drive shaft tube to clamp the drive shaft tube at a predetermined transaxial location. Additionally, the drive shaft tube is further clamped at the second end thereof. Simultaneously with the further clamping of the drive shaft tube there is performed the further step of controlling the second clamping of the drive shaft tube to clamp the drive shaft tube at the predetermined transaxial location.  
           [0027]    In accordance with an apparatus aspect of the invention there is provided a novel shaft for transmitting rotatory motion at a plurality of transmission angles. The shaft is provided with a spider arrangement having a plurality of projections, and a yoke having a transaxial bore therethrough. The transaxial bore has a circumferential outer perimeter that is roller formed radially inward to limit the extent to which a projection of the spider arrangement will penetrate radially outward through the transaxial bore.  
           [0028]    In one embodiment of this apparatus aspect of the invention, the spider arrangement has two distal projections coaxially arranged with respect to each other, and the yoke has a further transaxial bore, the transaxial bore and the further transaxial bore being coaxial with respect to each other and accommodating therein respectively associated ones of the coaxially arranged distal projections of the spider arrangement, the further transaxial bore having a radially outer perimeter thereof roller formed radially inward to limit the extent to which the associated projection of the spider arrangement will penetrate radially outward through the further transaxial bore. The radially inwardly roller formed outer perimeters of the transaxial bore and the further transaxial bore eliminate transaxial translation of the spider arrangement, that is, the radially inwardly turned outer perimeters of the transaxial bore and the further transaxial bore are configured to achieve a zero tolerance condition to eliminate transaxial translation of the spider. In addition, the spider arrangement is transaxially disposed at the true running center of the yoke. Such a zero tolerance condition accommodates variations in the overall trunion width, the centerline to trunion end dimension of the spider, the thickness of the end of the bearing cup, the snap ring thickness, the groove thicknesses in the yoke bores, the groove to centerline dimension, the outside groove-to-groove dimension, etc. In addition, there may be provided a thrust bearing that is compressed to achieve a desired preload that maintains an acceptable articulation torque.  
           [0029]    In a further embodiment, there is further provided a bearing cap installed on a projection of the spider arrangement. The bearing cap is accommodated within the transaxial bore of the yoke. A snap ring is, in certain embodiments, installed on within the transaxial bore of the yoke. The roller formed radially outer perimeter is arranged to overlie a circumferential portion of the snap ring. In a highly advantageous embodiment, the roller formed radially outer perimeter being is to exclude a region corresponding to the diameter of a projection of the spider arrangement.  
           [0030]    In a specific illustrative embodiment of the invention, the step of installing the yoke on the first end of the shaft tube includes the further steps of:  
           [0031]    defining a shaft datum on the shaft tube;  
           [0032]    defining a yoke datum on the yoke; and  
           [0033]    installing the yoke on the first end of the shaft tube in a spatial relation responsive to the shaft datum and the yoke datum.  
           [0034]    The step of first rolling includes, in certain embodiments, the further step of initial first rolling wherein a rolling tool arrangement is permitted to float to center itself on the first bore. There are further provided the steps of:  
           [0035]    locking the rolling tool arrangement to prevent the rolling tool arrangement from floating; and  
           [0036]    final first rolling wherein the rolling tool arrangement urges the portion of the material of the yoke to overlie axially the respectively associated distal end of the spider arrangement.  
           [0037]    A step of terminating the step of final first rolling is performed in response to a measured distance of axial travel of the rolling tool arrangement. In other embodiments, rolling is terminated in response to a rate of change of a measured distance of axial travel of the rolling tool arrangement. The rate of change of a measured distance of axial travel of the rolling tool arrangement may, in certain embodiments, be determined with respect to an applied axial force. In other embodiments, it may be measured with respect to time. In a still further embodiment, the termination of the step of final first rolling is responsive to the passage of a predetermined period of time, which may be obtained from a stored table. The specific determined time may be responsive to the characteristics of the material being rolled.  
           [0038]    In a highly advantageous embodiment, the rolling tool arrangement is formed at least in part of carbide rollers that engage the material to be rolled.  
           [0039]    In a specific illustrative embodiment of the invention, the turned radially outer perimeter is arranged to exclude a region corresponding to the diameter of a projection of the spider arrangement. The shaft has a shaft datum surface defined by its exterior surface, and the yoke has a yoke datum surface defined by a machined annular surface, the shaft datum and the yoke datum being arranged in determined spatial relation with respect to each other, preferably coaxially.  
           [0040]    In accordance with a still further aspect of the invention wherein a novel rotatable shaft product is formed by a novel process, there are provided in the process the steps of:  
           [0041]    (a) first installing a yoke on a first end of a shaft tube, the yoke having first and second bores therethrough for receiving respective distal ends of a spider arrangement;  
           [0042]    (b) fixing the spider arrangement in a determined fixed spatial relationship with respect to the yoke; and  
           [0043]    (c) first roller forming an outer edge of the first bore to urge a portion of the material of the yoke to overlie radially the respectively associated distal end of the spider arrangement.  
           [0044]    In one embodiment of this product by process aspect of the invention, the step of (b) fixing the spider arrangement includes the further step of engaging axially counteracting supports into communication with the bearing cups on the spider arrangement. The step of engaging axially counteracting supports includes, in certain embodiments, the further step of synchronizing the axially counteracting supports whereby the spider arrangement is fixed in a determined spatial relationship with respect to the yoke. The step of engaging axially counteracting supports is performed, in a highly advantageous embodiment of the invention, during the step of first rolling to ensure a zero axial tolerance condition between the spider arrangement and the first and second bores of the yoke  
           [0045]    In accordance with a further embodiment of the invention, prior to performing the step of first roller forming an outer edge, there is provided the further step of second installing a fastening ring in the first bore radially overlying of the respectively associated distal end of the spider arrangement, and the step of roller forming the outer edge of the first bore to urge the portion of the material of the yoke to overlie the fastening ring.  
           [0046]    Prior to performing the step of roller forming an outer edge of the first bore, there is provided the further step of third installing a bearing cap in the first bore for supporting rotatively within the first bore the respectively associated distal end of the spider arrangement. In addition, in a yet further embodiment, there are provided in the inventive process the further steps of:  
           [0047]    repeating step for the second bore; and  
           [0048]    second roller forming an outer edge of the second bore to urge a portion of the material of the yoke to overlie radially the respectively associated distal end of the spider arrangement.  
           [0049]    Prior to performing the step of second roller forming an outer edge of the second bore, there is provided the further step of third installing a further bearing cap in the second bore for supporting rotatively within the second bore the respectively associated distal end of the spider arrangement. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0050]    Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which:  
         [0051]    [0051]FIG. 1 is a simplified schematic front plan representation of an arrangement constructed in accordance with the principles of the invention for producing a novel vehicle drive shaft;  
         [0052]    [0052]FIG. 2 is a simplified schematic side plan representation of the arrangement of FIG. 1;  
         [0053]    [0053]FIG. 3 is a simplified schematic side plan representation of the arrangement of FIG. 1 illustrating a synchronization and centering arrangement for ensuring that the vehicle drive shaft is clamped at a determined axial location;  
         [0054]    [0054]FIG. 4 is the simplified schematic side plan representation of FIG. 3 illustrating additional components and details, and further illustrating transaxial displacement of the vehicle drive shaft clamping assembly to illustrate clamping and release of the vehicle drive shaft;  
         [0055]    [0055]FIG. 5 is a simplified schematic front plan representation of the synchronization and centering arrangement;  
         [0056]    [0056]FIG. 6 is the simplified schematic front plan representation of the synchronization and centering arrangement of FIG. 5, illustrating additional components and details;  
         [0057]    [0057]FIG. 7 is the simplified schematic side plan representation as in FIG. 3, but further showing the rotary tooling that roll forms the perimeter of outer edge of the bores of a yoke, and further illustrating a more detailed view of the radiative tooling in engagement with the yoke of a Cardan joint;  
         [0058]    [0058]FIG. 8 is an enlarged simplified schematic representation of the radiative tooling in engagement with the yoke of a Cardan joint;  
         [0059]    [0059]FIG. 9 is an enlarged simplified schematic representation the vehicle drive shaft being secured in place by clamps;  
         [0060]    [0060]FIG. 10 is a simplified schematic representation of a motor and speed reduction gearbox for delivering rotatory energy to the radiative tooling (not shown in this figure);  
         [0061]    [0061]FIG. 11 is a partially fragmented simplified sketch of a novel vehicle drive shaft having a yoke of a Cardan joint embodiment of the invention that has been subjected to the inventive process;  
         [0062]    [0062]FIG. 12 is a partially fragmented simplified representation of a Cardan joint embodiment of the invention that has been subjected to the inventive process;  
         [0063]    [0063]FIG. 13 is a simplified schematic front plan representation of a synchronization and centering arrangement illustrating the rods that retain the spider arrangement in fixed relation to the vehicle drive shaft clamping arrangement (not shown in this figure);  
         [0064]    [0064]FIG. 14 is a simplified schematic side plan representation of the arrangement of FIG. 13; and  
         [0065]    [0065]FIG. 15 is a simplified schematic side plan representation illustrating the spatial relationship between the radiative roll forming tooling, the rods that retain the spider arrangement in fixed relation, and the vehicle drive shaft clamping arrangement. 
     
    
     DETAILED DESCRIPTION  
       [0066]    [0066]FIG. 1 is a simplified schematic front plan representation of a spider installation arrangement  100  constructed in accordance with the principles of the invention for producing a novel vehicle drive shaft  110  having a first Cardan joint  112  coupled to a first end of vehicle drive shaft  110 , and a second Cardan joint  114  coupled to a second end of vehicle drive shaft  110 . Spider installation arrangement  100  is formed generally of a first tooling assembly  120 , a second tooling assembly  122 , and a base  124 , base  124  having an upper rail arrangement  130  and a lower rail arrangement  132 . The upper and lower rail arrangements are adapted to permit the second tooling assemblies to be translatable laterally in the directions of dual-headed arrows  135  and  136 , respectively, and thereby accommodate vehicle drive shafts of difference lengths.  
         [0067]    First tooling assembly  120  and second tooling assembly  122  are each provided with a respective associated one of first upper rotating die  140  and second upper rotating die  141 . In addition, the first and second tooling assemblies are each provided with a respective associated one of a first lower rotating die  144  and a second lower rotating die  145 . As will be described in greater detail hereinbelow, the first upper and lower rotating dies, which are installed on first tooling assembly  120 , serve to install the first Cardan joint spider (not specifically identified in this figure) in first Cardan joint  112 , and similarly, the second upper and lower rotating dies, which are installed on second tooling assembly  122 , serve to install the second Cardan joint spider (not specifically identified in this figure) in second Cardan joint  114 . During installation of the first and second spiders in this specific illustrative embodiment of the invention, the Cardan joints and vehicle drive shaft  110  are maintained in a predetermined coaxial relationship that corresponds to the true vehicle running center (“TVRC”). In the present embodiment, the TVRC is coaxial with the longitudinal axis (not shown) of vehicle drive shaft  110 . Such centering of the vehicle drive shaft and the first and second Cardan joints reduces imbalance and NVH, as previously noted, during operation of the vehicle (not shown) in which the vehicle drive shaft of the present invention is installed.  
         [0068]    Each of first upper and first lower rotating dies  140  and  144 , and second upper and second lower rotating dies  141  and  145  have a respective associated source of rotatory energy in the form of electric motors  150 - 153 . Each such electric motor has coupled thereto an associated one of reduction gear assemblies  155 - 158 .  
         [0069]    In FIG. 1, the drive shaft is fully assembled with the flange yoke on the left side, the spline yoke on the right side and all spiders, bearings and snap rings. The bearings and snap rings are not installed to their full depth in any of the yokes, because they will be centered and preloaded as part of the operation of this machine prior to roll forming, as will be discussed in detail below. In operation, the drive shaft is manually loaded to the “load assist” supports, then the operator positions the flange yoke to the left hand clamp fixture and manually actuates the clamp lever ( 415  in FIG. 15). The operator then positions the rest of the drive shaft in line with the tube clamp jaws, which then hydraulically advance, clamping and centralizing the tube to the flange yoke. At the same time, the spline clamp jaws hydraulically advance clamping and centralizing the spline yoke to the tube. Assembly is accomplished in only one plane (one set of spider bearings per joint) at a time, then the bearings are compressed to the spider centralizing the yoke to the tube and setting a bearing preload. After roll forming the bearing retainer edge, the shaft is automatically unclamped, rotated 90 degrees (by actuator  420  in FIG. 15) and the procedure is then repeated on the second set of bearings of that joint. Two or more joints can be centralized, preloaded, and rolled at a time.  
         [0070]    [0070]FIG. 2 is a simplified schematic side plan representation of spider installation arrangement  100  of FIG. 1. Elements of structure that previously have been discussed are similarly designated. In FIG. 2, first tooling assembly  120  is shown without first upper rotating die  140  or first lower rotating die  144 . First Cardan joint  112  is presented in an end view in this figure, thereby showing a four-holed mounting flange  170  of first Cardan joint  112 . More specifically, four-holed mounting flange  170  is coupled to vehicle drive shaft  110  via the Cardan joint spider (not shown in this figure). In use in a vehicle (not shown), four-holed mounting flange  170  will be coupled to the pinion gear (not shown) of the differential gear assembly (not shown) of the vehicle. The other end of vehicle drive shaft  110  (not shown in this figure) will engage the output spline shaft (not shown) of the vehicle&#39;s transmission (not shown).  
         [0071]    [0071]FIG. 3 is a simplified schematic side plan representation of spider installation arrangement  100  of FIG. 1 illustrating a synchronization and centering arrangement  200  of first tooling assembly  120  for ensuring that vehicle drive shaft  110  is clamped at a determined axial location that corresponds to the TVRC. A similar synchronization and centering arrangement is provided in this specific illustrative embodiment of the invention for second tooling assembly  122  (not shown in this figure). Elements of structure that previously have been discussed are similarly designated. As shown in FIG. 3, clamping of vehicle drive shaft  110  is effected by translating vertically an upper clamp jaw  210  in the direction of arrow  211 , and simultaneously translating vertically lower clamp jaw  212  in the direction of arrow  213 . Upper clamp jaw  210  and lower clamp jaw  212  are each provided with a clamping gripper (not shown in this figure) that communicates with vehicle drive shaft  110  and exerts the clamping force thereto. See, for example, upper and lower clamping grippers  230  and  232  in FIG. 4.  
         [0072]    Referring again to FIG. 3, it is important that vehicle drive shaft  110  be clamped and retained in a predetermined axial location, and precision in such axial positioning cannot be achieved unless the upper and lower clamp jaws are controlled in their respective vertical translation. Control is achieved, as previously noted, by operation of synchronization and centering arrangement  200  which is in the form of a rotatory synchronization element  220  that is coupled by a link  222  to upper clamp jaw  210  and by a further link  224  to lower clamp jaw  212 .  
         [0073]    The translation of upper clamp jaw  210  in the direction of arrow  211  (and opposite thereto during unclamping) is achieved in this specific illustrative embodiment of the invention by operation of an hydraulic actuator  227 . Similarly, the translation of lower clamp jaw  212  in the direction of arrow  213  (and opposite thereto during unclamping) is achieved in this specific illustrative embodiment of the invention by operation of an hydraulic actuator  228 . Both clamp jaws will travel in this specific illustrative embodiment of the invention for identical distances (in opposite directions) at equal rates of speed by operation of synchronization and centering arrangement  200 . It is to be understood, however, that persons of skill in the art can configure different forms of synchronization and centering arrangements to achieve other or unequal rates, or asymmetrical amounts, of displacement of the clamp jaws for other specific applications or embodiments.  
         [0074]    [0074]FIG. 4 is the simplified schematic side plan representation of spider installation arrangement  100  of FIG. 3 illustrating synchronization and centering arrangement  200  of first tooling assembly  120  in plural positions for ensuring that vehicle drive shaft  110  is clamped at a determined axial location that corresponds to the TVRC. Elements of structure that previously have been discussed are similarly designated, and there is also shown in this figure additional elements of structure (not specifically designated). This figure illustrates rotatory synchronization element  220  rotated counter-clockwise whereby link  222  is displaced upward to the position of link  222 ′ and link  224  is displaced downward to the position of link  224 ′. In this figure, vehicle drive shaft  110  is in communication with upper clamping gripper  230  and lower clamping gripper  232 .  
         [0075]    [0075]FIG. 5 is a simplified schematic front plan representation of first tooling assembly  120  showing in greater detail the first end of vehicle drive shaft  110  and first Cardan joint  112  installed thereon. A spider  240  of first Cardan joint  112  is shown cross-sectionally and coupled to four-holed mounting flange  170  (also shown in cross-section). In this specific illustrative embodiment of the invention, a shaft datum for vehicle drive shaft  110  is defined on the outer surface thereof. Similarly, a yoke datum is defined on a machined surface  111  of the yoke. As shown, the vehicle drive shaft and the yoke are arranged in relation to one another in accordance with the respective datums.  
         [0076]    Although some elements of structure have been removed from the depiction of first tooling assembly  120  in FIG. 5 for the sake of improving clarity and comprehension of the invention, other structural elements that were not viewable in FIG. 4 are shown in FIG. 5. For example, it is seen in FIG. 5 that the extent of vertical translation of upper clamp jaw  210  is detected by a sensor assembly  250  having sensors  252  and  253  that detect the proximity of detectable elements  255  and  256 . Similarly, the extent of vertical translation of lower clamp jaw  212  is detected by a sensor assembly  260  having sensors  262  and  263  that detect the proximity of detectable elements  265  and  266 .  
         [0077]    [0077]FIG. 6 is the simplified schematic front plan representation of the synchronization and centering arrangement of FIG. 5, illustrating additional components and details. Elements of structure that previously have been discussed are similarly designated. As shown in FIG. 6, clamping gripper  230  and lower clamping gripper  232  are shown to be in gripping communication with vehicle drive shaft  110 . There is additionally shown in this figure that clamping gripper  230  is affixed to upper clamp jaw  210  by a plurality of threaded fasteners  268 , and lower clamp jaw  212  is similarly affixed to lower clamp jaw  212  by a second plurality of threaded fasteners  269 .  
         [0078]    [0078]FIG. 7 is the simplified schematic side plan representation as in FIG. 3, and further shows details of first upper rotating die  140  and first lower rotating die  144 , the coverings thereof having been removed, and further illustrate a more detailed view of the rotating die in engagement with the yoke of first Cardan joint  112 . As will be described herein, the rotating dies roll form the perimeter of outer edge of the radially distal bores of a yoke of first Cardan joint  112  to secure therewith in spider  240 . In the specific illustrative embodiment of the invention, the rotating dies are operated at approximately 30 rpm. Elements of structure that previously have been discussed are similarly designated.  
         [0079]    Referring to first upper rotating die  140  in FIG. 7, there is first provided an upper centering rod  270  that is accommodated within a through bore  272  so as to apply a downward force on a bearing cap  274  that is installed on upwardly extending end  276  of spider  240 . The downward urge applied by upper centering rod  270  is counteracted by an upward urge applied by lower centering rod  280 . Upper centering rod  270  and lower centering rod  280  are controlled to maintain spider  240  positioned, in this specific illustrative embodiment of the invention, so as to be centered with the longitudinal axis of vehicle drive shaft  110  (not shown in this figure). In a manner similar to that of upper centering rod  270 , lower centering rod  280  that is accommodated within a through bore  282  so as to apply an upward force on a lower bearing cap  284  that is installed on downwardly extending end.  286  of spider  240 .  
         [0080]    While spider  240  is retained in coaxial position by operation of upper centering rod  270  and lower centering rod  280 , as described immediately hereinabove, first upper rotating die  140  and first lower rotating die  144  are urged toward respective ones of upwardly extending end  276  and downwardly extending end  286  of spider  240 . With reference to first upper rotating die  140 , this figure shows that there is provided a first spindle  300  and a second spindle  302  that is shown partially cross-sectionally. Each of first spindle  300  and second spindle  302  is provided with a respective one of a first rolling tool  304  and second rolling tool  306 . The first and second rolling tools are urged toward the upper edge of through bore  272  which, as will be described below, is rolled over a snap ring (not shown in this figure) and bearing cap  274  to prevent same from being displaced upward within through bore  272 . A similar rolling of the lowermost extending edge of lower through bore  282  is achieved by first lower rotating die  144  which is urged upward as first upper rotating die  140  is urged downward. First upper rotating die  140  is rotated upon actuation of electric motor  150 . First lower rotating die  144  is rotated upon actuation of electric motor  152 .  
         [0081]    [0081]FIG. 8 is an enlarged simplified schematic partially cross-sectional front plan representation of first upper rotating die  140  and first lower rotating die  144  in engagement with the yoke of first Cardan joint  112 . Elements of structure that previously have been discussed are similarly designated. As previously stated, first upper rotating die  140  is first provided an upper centering rod  270  that is accommodated within through bore  272  so as to apply a downward force on a bearing cap  274  that is installed on upwardly extending end  276  of spider  240 . The downward urge applied by upper centering rod  270 , as noted, is counteracted by the upward urge applied by lower centering rod  280 . Upper centering rod  270  and lower centering rod  280  maintain spider  240  centered with the longitudinal axis of vehicle drive shaft  110 . In a manner similar to that of upper centering rod  270 , lower centering rod  280  that is accommodated within a through bore  282  so as to apply an upward force on a lower bearing cap  284  that is installed on downwardly extending end  286  of spider  240 . First rolling tool  304  and second rolling tool  306  are shown to be in communication with upper edge  310  of through bore  272 . In this specific illustrative embodiment of the invention, the rolling tools are formed of carbide.  
         [0082]    As described hereinabove in relation to FIG. 7, while spider  240  is retained in coaxial position relative to vehicle drive shaft  110  by operation of upper centering rod  270  and lower centering rod  280 , first upper rotating die  140  and first lower rotating die  144  are urged toward respective ones of upwardly extending end  276  and downwardly extending end  286  of spider  240 . During this operation the opposite Cardan yoke (90° out of position from the yoke portions being roll formed) is held in proper position by a corresponding clamping device (not shown), notwithstanding the application of a reload transmitted by upper centering rod  270  and lower centering rod  280  via the respective bearing caps and snap rings. The first and second rolling tools are urged toward upper edge  310  of through bore  272  which is rolled over snap ring  311  and bearing cap  274 , thereby blocking same from passing upward within through bore  272 . In a highly advantageous embodiment of the invention, the edge roll (not shown in this figure) that is effected by the rolling tools extends radially inward so as to overlie snap ring  311 , without extending radially inward over bearing cap  274 . This will permit disassembly of first Cardan joint  112  in a conventional manner by removal of snap ring  311 . Of course, a snap ring need not be provided in the practice of the invention, and first rolling tool  304  and second rolling tool  306  can be configured by persons of ordinary skill in the art to extend the rolled upper edge  310  of through bore  272  radially inward to overlie bearing cap  274 . In addition, the present specific illustrative embodiment of the invention is shown in this figure with snap ring  311  installed in a correspondingly dimensioned snap ring groove  313  in through bore  272 . In certain embodiments of the invention, the cost associated with the formation of the snap ring groove can be eliminated by use of an enlarged outer radius for through bore  272  that would accommodated snap ring  311 , the snap ring being retained by the radially inwardly rolled upper edge  310  of through bore  272 , formed as described herein.  
         [0083]    A similar rolling of the lowermost extending edge of lower through bore  282  is achieved by operation of first lower rotating die  144  which is urged upward contemporaneously with first upper rotating die  140  being urged downward. As previously noted, spider  240  is maintained in the coaxial TVRC position by operation of upper centering rods  270  and  280  which are urged to apply balanced counteracting forces with respect to each another. The balanced counteracting forces retain the combination of spider  240 , bearing cap  274 , and lower bearing cap  284 , as well as snap rings  311  and  312  in certain embodiments, on the TVRC, which in this specific illustrative embodiment of the invention, is coaxial with longitudinal axis  314  of vehicle drive shaft  110 .  
         [0084]    First upper rotating die  140  is rotated upon actuation of electric motor  150  (not shown in this figure). Similarly, first lower rotating die  144  is rotated upon actuation of electric motor  152  (not shown in this figure). Such rotation of the rotating dies causes the rolling of upper edge  310  of through bore  272  and lower edge  315  of through bore  282 .  
         [0085]    [0085]FIG. 8 additionally shows clamping gripper  230  and lower clamping gripper  232  in engagement with vehicle drive shaft  110 . FIG. 9 is an enlarged simplified schematic representation showing vehicle drive shaft  110  (in end view) being secured in place by clamping gripper  230  and lower clamping gripper  232 . As noted in connection with FIG. 6, clamping gripper  230  is coupled to upper clamp jaw  210  (not shown in this figure) by the four threaded fasteners  268  shown in FIG. 9. Similarly, lower clamping gripper  232  is coupled to lower clamp jaw  212  (not shown in this figure) by the four threaded fasteners  269  also shown in FIG. 9. As further shown in FIG. 8, clamping gripper  230  and lower clamping gripper  232  grip vehicle drive shaft  110  on its circumferential datum line  317 , which is a circumferential reference line in relation to which manufacturing dimensions are established during manufacture of vehicle drive shaft  110 .  
         [0086]    In operation, the centering rods apply a bearing press force to the outside ends of the bearing cups that are vertically positioned in the machine. This force pushes the bearing cups into contact with the vertical trunnions of the spider. The horizontal trunnions of the spider are held in location by the horizontal bearings installed in the accompanying yoke bores. The horizontal yoke bores are located by the equalizing links and jaws and held central to the flange yoke mounted on the opposing clamp fixture. During the roller forming process, the force applied to the edge of the snap ring retention bore causes the yoke arms to flex. As the arm flexes toward the center of the spider it moves down on the bearing, because the bearing is solid against the spider. When the roller is rotated 90°, the yoke arm flexes upward, lifting the bearing, and therefore backing it away from the spider. This backing away of the bearings causes loss of the compression preload of the thrust bearings (located in the bearing cups) against the end of the spider trunnions. The compression force (which is selectable for different applications) will overcome the spring-back force against the bearing cups and maintain bearing thrust washer preload.  
         [0087]    In this embodiment, each centering rod is independently actuated and force-controlled. The force is measured by a pressure transducer mounted in the hydraulic supply line to the corresponding cylinder actuator. The roller actuator slides are linked with a common hydraulic cylinder acting as an equalizing force mechanism. The force is monitored and controlled with feedback from a pressure transducer mounted in the hydraulic supply line to this cylinder.  
         [0088]    [0088]FIG. 10 is a simplified schematic representation of electric motor  150  and its associated reduction gear assembly  155  for delivering rotatory energy to first upper rotating die  140  (not shown in this figure). As described in connection with FIG. 8, the rotation of the upper and lower rotating dies results in the rolling of the outer edges of the through bores thereby retaining spider  240  in coaxial alignment with the TVRC. The rotatory energy of electric motor  150  is delivered at a reduced rate of rotation at output shaft  320 . The output shaft is coupled to first upper rotating die  140 .  
         [0089]    [0089]FIG. 11 is a partially fragmented simplified sketch of a novel vehicle drive shaft  350  embodiment of the invention that has been subjected to the inventive process, having a yoke  355  of a Cardan joint (not specifically designated) attached to end  352  of vehicle drive shaft  350 . Elements of structure that previously have been discussed are similarly designated. As shown in this figure, yoke  355  has an ear  357  that has a through-hole  360  having a rolled outermost edge  362  that is show to have been rolled to overlie a snap ring  364 . Snap ring  364  is shown to overlie the uppermost surface of a bearing cap  366 . Thus, rolled outermost edge  362  prevents snap ring  364  from being released outward of through-hole  360 , and snap ring  364  prevents bearing cap  366  from exiting through-hole  360 . As previously noted, snap ring  364  may be eliminated in certain embodiments of the invention. It should be noted that variations in the thicknesses of production snap rings will not affect the coaxial alignment with the TVRC in certain embodiments of the invention where centering rods  270  and  280  (not shown in this figure) are configured to communicate directly with the bearing caps.  
         [0090]    [0090]FIG. 12 is a partially fragmented and partially phantom simplified representation of the embodiment of FIG. 11 that has been subjected to the inventive process described herein. Elements of structure that previously have been discussed are similarly designated. As shown in this figure, vehicle drive shaft  350  is coupled to yoke  355  of Cardan joint  370  that has been coupled thereto by a weld  372 . A spider  375  is shown to have installed thereon a bearing cap  377  and a further bearing cap  378 , each of which is associated with a respective one of ears  380  and  381  of a four-holed mounting flange  383 .  
         [0091]    With reference to the structure of ear  380  shown in phantom representation, the details of the rolled edge structure are shown in greater detail in the magnified view. As shown therein, ear  380  has an aperture  385  therethrough, the outermost edge  387  thereof is shown to have been rolled to the form of an inverted truncated pyramid. A snap ring  389  is shown in this embodiment to have been deposited in an outer region  390  of enlarged diameter of aperture  385 . The diametrical enlargement of outer region  390  is shown exaggerated and not to scale for the sake of improving comprehension of the invention. In this specific illustrative embodiment of the invention, therefore, it is noteworthy that there is not provided an internal groove for accommodating the snap ring, as is the case with the embodiment of FIG. 8, which shows, for example, snap ring  311  installed in snap ring groove  313 . Thus, in the embodiment of FIG. 12, a cost saving is achieved.  
         [0092]    Further in regard of FIG. 12, it is noted that the radially inner extent of rolled outermost edge  387  does not extend to a diameter less than that of bearing cap  377 .  
         [0093]    Accordingly, conventional disassembly of the Cardan joint is not precluded by the present inventions, since upon removal of snap ring  389  using conventional tools, bearing cap  377  will pass through the opening within rolled outermost edge  387 , whereupon the Cardan joint can be entirely disassembled, or the bearing caps thereof be replaced.  
         [0094]    [0094]FIGS. 13 and 14 are simplified schematic front and side plan representations, respectively, of a synchronization and centering arrangement for spider  240  illustrating additional elements of structure associated with upper centering rod  270  and lower centering rod  280  that retain spider  240  in fixed relation to the vehicle drive shaft clamping arrangement (not shown in this figure) and the TVRC. Elements of structure that previously have been discussed are similarly designated. In this specific illustrative embodiment of the invention, upper centering rod  270  is urged in the direction of arrow  400  by operation of an actuator  402 . Similarly, lower centering rod  280  is urged in the direction of arrow  404  by operation of an actuator  406 . In this embodiment of the invention, actuators  402  and  406  are hydraulic devices. Actuator  402  is coupled to upper centering rod  270  via a floating coupling  417  and actuator  406  is coupled to lower centering rod  280  via a floating coupling  418 . The upper and lower centering rods apply a controlled force to bearing caps  377  and  378  (not shown in this figure, see, FIG. 12) during the roll forming process. This reload must be maintained between each set of bearings located 90° from each other to prevent drive line oscillations during rotation of the vehicle drive shaft in the vehicle.  
         [0095]    In the representations of FIGS. 13 and 14, there is shown second Cardan joint  114  coupled to the second end of vehicle drive shaft  110 . The Cardan joint couples a spline  410  that will engage the output spline shaft (not shown) of the vehicle&#39;s transmission (not shown). These figures additionally show bearings  414  that are used to support the roller heads (not shown in this figure) and associated drivers (not shown in this figure). See, for example, FIGS. 2 and 7.  
         [0096]    [0096]FIG. 15 is a simplified schematic side plan representation illustrating the spatial relationship between the rotary tooling, the rods that retain the spider in fixed relation, and the vehicle drive shaft clamping arrangement. Elements of structure that previously have been discussed are similarly designated. As shown in this figure, there is provided an actuator  420  that is coupled via a linkage arrangement  422  to rotate the vehicle drive shaft (not shown in this figure) by 90°. Thus, after a first set of aperture edges are roll formed as herein described, actuator  420  causes the vehicle drive shaft to be rotated, whereupon the second pair of aperture edges are oriented to be roll formed. There is additionally shown in FIG. 15 a handle  425  that actuates the flange clamp arrangement. The position of handle  425  is monitored by a sensor  427 .  
         [0097]    Although the invention has been described in terms of specific embodiments and applications, persons skilled in the art can, in light of this teaching, generate additional embodiments without exceeding the scope or departing from the spirit of the claimed invention. Accordingly, it is to be understood that the drawing and description in this disclosure are proffered to facilitate comprehension of the invention and should not be construed to limit the scope thereof.