Abstract:
An apparatus for processing a drive shaft ( 11 ) for a vehicle, the drive shaft ( 11 ) having a longitudinal axis and first and second ends. There is provided a drive arrangement for coupling to the first end of the drive shaft and applying a rotatory force to the drive shaft ( 11 ). A second end support arrangement rotationally supports the drive shaft ( 11 ) at its second end. Also, a transaxial drive ( 35 ) for applying a transverse force in a direction transverse to the longitudinal axis of the drive shaft ( 11 ). The transaxial drive includes a transaxially displaceable roller arrangement for communicating with an outer surface of the drive shaft ( 11 ) in a region thereof intermediate of the drive arrangement and the support arrangement, via which the transverse force is applied. The transverse force has a magnitude sufficient to cause bending of the drive shaft ( 11 ) in the direction transverse to the longitudinal axis thereof as the drive shaft is rotated. In some embodiments, the transverse force has a magnitude sufficient to cause plastic deformation of the drive shaft ( 11 ) in the direction transverse to the longitudinal axis thereof as the drive shaft is rotated.

Description:
RELATIONSHIP TO OTHER APPLICATIONS 
   This application is a 35 USC 371 of PCT/US02/26567, filed Aug. 20, 2002. 
   This application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. 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 
   1. Field of the Invention 
   This invention relates generally to methods and apparatus for straightening shafts, and more particularly, to a system for truing large shafts, such as vehicle drive shafts. 
   2. Description of the Related Art 
   Vehicle drive shafts are large and tubular, and difficult to manufacture in a manner that they are rendered consistently true. Such shafts, among other shaft products, are very sensitive to bends in their main shaft portions. These imperfections cause noise, vibration, and harshness (“NVH”) issues, and also make final correction balance of the product difficult. One approach to achieving a correction to a vehicle drive shaft is to rotate the vehicle drive shaft while a human operator observes displacements resulting from irregularities. The human operator will apply a force upon the vehicle drive shaft in a direction that tends to compensate for the observed displacements. This not only is a slow process that is difficult to implement in a modern manufacturing environment, it requires significant skill on the part of the human operator. Clearly, the results will vary with the level of skill of the human operator. 
   The need for increased accuracy in the truing of vehicle drive shafts results in part from the significantly reduced noise emissions from other modern vehicle components, particularly including the drive train. Modern vehicles are sufficiently quiet that drive shaft noise is becoming an increasing portion of overall vehicle operating noise. 
   To date many tubular products have been manufactured with an excessive amount of run out or bending imperfections. Manufacturers usually attempt to straighten the tubular product using primitive methods such as a static press force applied between two “V” blocks directly on the shaft. The operator approximates how much force or tube deflection is required for straightening the assembly. This is done by rotating the tube between two “V” blocks and monitoring the run out of the assembly on a dial indicator gauge. After establishing the maximum run out the operator will position the tube on its high point, and force the tube into plastic deformation using a ram. The operator will then measure again the amount of bend in the product and repeat the process as many times as needed to reduce the shaft bending into an acceptable tolerance. Bending in this case is defined as the deflection measured between the three points identified by the “V” blocks, and the dial indicator. It should be noted that these points are not the same areas to which the vehicle would react to in actual operation. Many experts in the field of drive shaft manufacturing feel the current straightening operations actually do more harm than good. 
   It is, therefore, an object of this invention to provide a system whereby a vehicle drive shaft can quickly and simply be trued. 
   It is another object of this invention to provide a system whereby a vehicle drive shaft can accurately be trued without relying on the skill of a human operator. 
   The present invention significantly reduces the imperfections in a tubular or cylindrical assembly related to bending. It is therefor well suited to drive shaft manufacturing. Most importantly the invention is also designed to straighten the tubular assembly relative to a rotating datum. The rotating datum is referred to as the True Vehicle Running Center (TVRC) of the product. This process of truing is accomplished at high rates of speed, which suits the operation well to mass production. 
   SUMMARY OF THE INVENTION 
   The foregoing and other objects are achieved by this invention which provides an apparatus for processing a drive shaft for a vehicle, the drive shaft having a longitudinal axis and first and second ends. In accordance with the invention, there is provided a drive arrangement for coupling to the first end of the drive shaft and applying a rotatory force to the drive shaft. A second end support arrangement rotationally supports the drive shaft at its second end. Also, a transaxial drive for applying a transverse force in a direction transverse to the longitudinal axis of the drive shaft. 
   In one embodiment, the transaxial drive includes a transaxially displaceable roller arrangement for communicating with an outer surface of the drive shaft in a region thereof intermediate of the drive arrangement and the support arrangement, via which the transverse force is applied. The transverse force has a magnitude sufficient to cause bending of the drive shaft in the direction transverse to the longitudinal axis thereof as the drive shaft is rotated. In some embodiments, the transverse force has a magnitude sufficient to cause plastic deformation of the drive shaft in the direction transverse to the longitudinal axis thereof as the drive shaft is rotated. 
   In a further embodiment, the second end support arrangement includes first and second rollers arranged to support rotatively the drive shaft in a direction counter to that of the transverse force. Also, the first and second rollers of the second end support arrangement are each provided with radially extended central portions. 
   There is further provided a first end support arrangement for rotationally supporting the drive shaft at its first end. The first end support arrangement includes first and second rollers arranged to support rotatively the drive shaft in a direction counter to that of the transverse force. The first and second rollers of the first end support arrangement are each provided with radially extended central portions. Additionally, the first end support arrangement includes third and fourth rollers arranged to support rotatively the drive shaft in a direction opposite to that of the first and second rollers of the first end support arrangement. Third and fourth rollers of the first end support arrangement are each provided with radially extended central portions. 
   In a further embodiment, the transaxial drive includes an hydraulic ram for applying an axial ram force and a linkage arrangement for delivering the axial ram force to the transaxially displaceable roller arrangement. The drive arrangement causes the drive shaft to be rotated at a rate of rotation of approximately between 300 and 6000 rpm. 
   In some embodiments, the drive shaft has angularly displaceably coupled thereto a second drive shaft portion, and there is further provided a second drive shaft portion support arrangement for supporting the second drive shaft portion rotatably in fixed axial relation to the drive shaft as the drive shaft is rotated. The fixed axial relation may, in some embodiments, be a substantially coaxial relationship. There is further provided a universal coupler for coupling the second drive shaft portion to the drive shaft, which may be a Thomson shaft. 
   The second drive shaft portion support arrangement is configured to permit axial displacement of the second drive shaft portion in response to non-trueness of the drive shaft and the application of the transverse force in the direction transverse to the longitudinal axis of the drive shaft. 
   In accordance with a method aspect of the invention, there is provided a method of improving the trueness of a drive shaft of a vehicle, the drive shaft having a longitudinal axis and first and second ends, the method having the steps of: 
   installing the drive shaft onto a support arrangement that supports the drive shaft rotatively at its first and second ends; 
   rotating the drive shaft about its longitudinal axis; 
   applying a transaxial force to the drive shaft in a region intermediate of the first and second ends; and 
   releasing the transaxial force. 
   In one embodiment, there is provided the further step of applying includes the step of applying the transaxial force having a magnitude sufficient to bend the drive shaft as it is rotated. The step of rotating the drive shaft about its longitudinal axis includes the step of rotating the drive shaft at a rate of rotation of approximately between 300 and 6000 rpm. There is also provided the further step of supporting in a second support arrangement a second drive shaft portion that is angularly displaceably coupled to the drive shaft. 
   In other embodiments, there are provided the steps of: 
   permitting the second drive shaft portion to be displaced longitudinally in the second support arrangement in response to non-trueness of the drive shaft; and 
   permitting the second drive shaft portion to be displaced longitudinally in the second support arrangement in response to the step of applying a transaxial force to the drive shaft. 
   In other embodiments, the step of applying a transaxial force to the drive shaft includes the steps of: 
   actuating an hydraulic cylinder to produce an axial displacement of a displacement element; 
   coupling the displacement element to a roller arrangement; and 
   engaging the roller arrangement to an outer surface of the drive shaft in a region of the drive shaft intermediate of the first and second ends thereof. 
   In accordance with a product aspect of the invention, there is provided a vehicle drive shaft product formed by the process of: 
   a. installing a hollow drive shaft tube onto a support arrangement that supports the hollow drive shaft tube rotatively at its first and second ends; 
   b. rotating the hollow drive shaft tube about its longitudinal axis; 
   c. applying a transaxial force to the hollow drive shaft tube in a region intermediate of the first and second ends, the transaxial force having a magnitude sufficient to bend the hollow drive shaft tube; 
   d. releasing the transaxial force; and 
   e. removing the hollow drive shaft tube from the support arrangement; 
   wherein the thus processed hollow drive shaft tube is the vehicle drive shaft product having a trueness characteristic within a range of approximately between ±0.004 inches. 
   The thus processed hollow drive shaft tube is the vehicle drive shaft product has a trueness characteristic within a range of approximately between ±0.002 inches. 
   There is further provided the step of repeating steps a. through e. with a second hollow drive shaft tube to produce a second vehicle drive shaft product also having a trueness characteristic within a range of approximately between ±0.004 inches. 
   Preferably, The thus processed second hollow drive shaft tube is a second vehicle drive shaft product having a trueness characteristic within a range of approximately between ±0.002 inches. 
   There is provided the further step of supporting in a second support arrangement a second drive shaft portion that is angularly displaceably coupled to the hollow drive shaft tube. The vehicle drive shaft product is the thus processed hollow drive shaft tube with the second drive shaft portion that is angularly displaceably coupled thereto. 
   In a further embodiment, there is provided the further step of permitting the second drive shaft portion to be displaced longitudinally in the second support arrangement in response to non-trueness of the drive shaft. Additionally, there is provided the further step of permitting the second drive shaft portion to be displaced longitudinally in the second support arrangement in response to the step of applying a transaxial force to the hollow drive shaft tube. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which: 
       FIG. 1  is a simplified schematic representation of a front plan view of an arrangement for truing a shaft constructed in accordance with the principles of the invention; 
       FIG. 2  is a simplified, partially cross sectional schematic representation of a top plan view of a roller support arrangement shown at the left-hand portion of the arrangement of  FIG. 1 ; 
       FIG. 3  is an end view from the left-hand side of the arrangement of  FIG. 1 ; 
       FIG. 4  is an end view from the right-hand side of the arrangement of  FIG. 1 ; 
       FIG. 5  is a top plan view of the arrangement of  FIG. 1 ; 
       FIG. 6  is a simplified schematic representation of a side plan view of the ram portion of the arrangement of  FIG. 1 ; 
       FIG. 7  is a simplified schematic representation of a front plan view of a further arrangement for truing a shaft constructed in accordance with the invention having a displaceable workpiece support arrangement for facilitating installation, holding, and removal of a workpiece; 
       FIG. 8  is a simplified partially cross-sectional schematic representation of a side plan view of a portion of the arrangement of  FIG. 7  for truing a shaft; 
       FIG. 9  is a simplified partially cross-sectional schematic representation of a side plan view of a further portion of the arrangement of  FIG. 7  for truing a shaft; and 
       FIG. 10  is a simplified schematic representation of a front plan view of a further arrangement for truing a shaft constructed in accordance with the invention. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is a simplified schematic representation of a front plan view of a truing arrangement  10  for truing a drive shaft  11  of the type that is used in the propulsion system of a motor vehicle, constructed in accordance with the principles of the invention. In this embodiment, drive shaft  11  is supported at respective ends thereof by respective roller pairs (not completely shown in this figure) that are installed rotatably in respective ones of support beds  15  and  16  that are supported on respective ones of bases  12  and  13 . Support bed  15 , in this specific illustrative embodiment of the invention, has associated therewith a further pair of support rollers (not completely shown in this figure) that are installed rotatably in a securing support bed  18 . In this specific illustrative embodiment of the invention, support bed  15  and securing support bed  18  are coupled to one another by a plurality of threaded posts  20 . 
     FIG. 2  is a simplified, partially cross sectional schematic representation of a top plan view of securing support bed  18  that is shown in the left-hand portion of  FIG. 1 .  FIG. 2  shows securing support bed  18  to have therein two rollers  22  and  23 , roller  23  being shown cross-sectionally. In one embodiment, all of the rollers in support beds  15  and  16  are identical to rollers  22  and  23 . Roller  22  is representative in this specific illustrative embodiment of the invention of all others of the stated rollers and is shown to have a radially extended central portion  24 , which is the portion that communicates with drive shaft  11 . 
   Referring once again to  FIG. 1 , there is shown extending upward from support bed  15  a portion of a roller  25  extending upwardly therefrom. Roller  25  is shown to have a radially extended central portion  26  that is shown to communicate with drive shaft  11  on a datum line  28  (shown in dashed format). 
     FIG. 3  is an end view from the left-hand side of the arrangement of  FIG. 1 . Elements of structure that previously have been discussed are similarly designated. As shown in this figure, drive shaft  11  is supported and restrained by communication with the four rollers, as previously described. Each such roller is also shown to have a radially extended central portion, not all of which are specifically designated. 
     FIG. 4  is an end view from the right-hand side of the arrangement of  FIG. 1 . Elements of structure that previously have been discussed are similarly designated. As shown in this figure, drive shaft  11  is supported by rollers  30  and  31 . Each such roller is also shown in this figure to have an associated one of radially extended central portions  32  and  33 , as previously described. 
   Referring once again to  FIG. 1 , there is additionally shown a ram arrangement  35  installed on a base  36 . Ram arrangement  35  is, in this specific illustrative embodiment of the invention, hydraulically actuated (hydraulic system not entirely shown) and is operated in response to actuation of an hydraulic cylinder  37  that is linked by links  38  and  39  to a press bar  40  via a restrained coupler  41 . Press bar  40  (also shown in  FIG. 6 ) has coupled thereto a pair of roller supports  43  and  44 , each of which carries a pair of rollers (not entirely shown in this figure) that will be discussed in greater detail in connection with  FIG. 6 , below. Only rollers  46  and  47  are shown in this figure. Unlike the previously described support and restraining rollers, rollers  46  and  47 , as well as the other rollers of these roller pairs, see, for example, roller  52  in  FIG. 6 , do not have a radially extended central portion. The surfaces of these rollers that communicate with drive shaft  11 , in this specific illustrative embodiment of the invention, are slightly curved, as shown. 
   In operation, drive shaft  11  is rotated, as will be discussed below in connection with the embodiment of  FIG. 10 . During such rotation, hydraulic cylinder  37  is actuated such that press bar  40 , and consequently the aforementioned roller pairs, of which rollers  46  and  52  ( FIG. 6 ) constitute one such pair, are urged downwardly in the direction of arrow  50 . In response to the applied lateral force, drive shaft  11  is deflected during the rotation. In this embodiment of the invention, the drive shaft is deflected beyond the limit of restoration that would be effective but for the rotation. Therefore, upon release of the lateral force applied by ram arrangement  35 , drive shaft  11  is restored to a straighter condition than before it being subjected to such a truing operation. 
     FIG. 5  is a top plan view of truing arrangement  10 , shown in  FIG. 1 . Elements of structure that previously have been discussed are similarly designated. Drive shaft  11  is shown to be supported, on its right hand side, by rollers  30  and  31 . 
     FIG. 6  is a simplified schematic representation of a side plan view of the ram portion of the arrangement of  FIG. 1 . It is to be understood, however, that any known suitable drive arrangement may be used in the practice of the invention. Elements of structure that previously have been discussed are similarly designated. This figure shows that roller support  44  supports a pair of rollers  47  (previously mentioned) and  52 . In this specific illustrative embodiment of the invention, both such rollers are configured with a slightly curved surface that communicates with drive shaft  11 . It is additionally seen that restrained coupler  41  is engaged with a track  54  via a further coupler  55  that is shown to be engaged on one side thereof to restrained coupler  41  and on its other side to track  54 . Such coupling ensures that rollers  47  and  52 , as well as roller  46  and its paired roller (neither of which is shown in this figure) travel exclusively in the directions of arrow  57 . 
     FIG. 7  is a simplified schematic representation of a front plan view of a truing arrangement  100  for truing a shaft constructed in accordance with the invention. In this simplified arrangement, a base  110  has installed thereon a shaft support  112  that, in this specific illustrative embodiment of the invention is provided with a pair of pillow blocks  114  and  115 . A shaft  120 , which may in certain embodiments be a Thompson shaft, is rotatably engaged with each of the pillow blocks, and is coupled, by means of a coupler that is designated generally in this figure as  122 , to a vehicle drive shaft  125 . The vehicle drive shaft is provided at its distal end with a further coupler that is designated generally in this figure as  127 . The further coupler is coupled at its distal end to further rotatable structure (not shown in this figure), which in some embodiments of the present invention may be similar to shaft support  112 , pillow blocks  114  and  15 , and shaft  120 . 
   Couplers  122  and  127  are configured to maintain a rotatory coupling irrespective of transaxial displacement of vehicle drive shaft  125  resulting from it being either in a non-true condition or deflected in response to the application of a lateral force in the central region thereof, as will be described below. In this specific illustrative embodiment of the invention, coupler  122  has a part clamp  121  coupled to bar clamp  123  via a tool steel ball  124 . Coupler  127  also is formed of two portions, a part clamp  128  and a lathe adapter  129 , which locate and clamp on the shaft&#39;s datum centerline (not specifically identified in this figure). 
   Once supported in a horizontal orientation, vehicle drive shaft  125  is rotated at approximately between 300 and 1500 rpm in this specific illustrative embodiment of the invention by the application of a rotatory force by operation of structure that is not shown in this figure. Persons of skill in the art readily can configure structure for imparting rotation to vehicle drive shaft  125 , and effect rates of rotation without being limited to range of rate of rotation set forth herein. 
   There is additionally installed on base  110  a frame  130 , which is in several respects similar, in this embodiment, to ram  35  described hereinabove in connection with  FIGS. 1 and 6 . In the specific illustrative embodiment of  FIG. 7 , an hydraulic press  132 , that will be described in greater detail in connection with  FIG. 8 , is attached at its upper end to frame  130 , and has installed on its lower end a pair of roller mounts  134  and  135 . Each such roller mount has installed thereon a respectively associated one of roller pairs  137  and  138 . In this figure, only one roller of each roller pair is shown. In a practical embodiment of the invention, the rollers can be adjusted for width and offset to accommodate shafts that have complex shapes, possibly due to crush zones. 
     FIG. 8  is a simplified partially cross-sectional schematic representation of a side plan view of a portion of truing arrangement  100  showing roller pair  138  in communication with vehicle drive shaft  125 . Elements of structure that previously have been mentioned are similarly designated. In this specific illustrative embodiment of the invention, the roller pairs apply a downward force on vehicle drive shaft  125  (in the direction of arrow  140 ), by operation of an actuator  142  that is hydraulically operated in this embodiment. Actuator  142  is coupled to one end of pivoted arm  144 , which is coupled at its distal portion to a link  146 . Thus, as actuator  142  is urged upwardly, link  146  and roller mount  135  coupled thereto are urged downwardly, thereby exerting a lateral force on rotating vehicle drive shaft  125 . 
   In operation, the downward force applied to vehicle drive shaft  125  is of a magnitude that, but for the rotation of the vehicle drive shaft, would cause a permanent deflection therein. That is, the force is sufficient to bend the vehicle drive shaft into plastic deformation, beyond its static elastic limit. During such deflection, the ends of vehicle drive shaft  125  are maintained in axial alignment by operation of couplers  122  and  127  that retain a fixed axial alignment. Upon effecting a slow release of the lateral load while the shaft is rotating, the vehicle drive shaft is corrected to a true center rotation. This process produces a near perfectly straight shaft relative to the true vehicle rotating center (“TVRC”). 
     FIG. 9  is a simplified partially cross-sectional schematic representation of a side plan view of a further portion of truing arrangement  100 , showing pillow block  115  with shaft  120  installed therein. The pillow blocks are constructed to withstand the lateral load applied to vehicle drive shaft  125  while same is rotated. 
     FIG. 10  is a simplified schematic front plan representation of a further arrangement  200  for truing a shaft constructed in accordance with the invention. In operation, a human operator (not shown) inserts a drive shaft section  250  after the weld yokes  251  and  252  are attached. Drive shaft  250  may, in certain embodiments, be a section of a drive shaft if the assembly is a multi piece design. Chuck jaws  260  in a first clamp head  261  are designed to clamp at the True Vehicle Rotating Center (TVRC), which is defined as the imaginary line connecting the center of the two rotating datum. The operator then indexes a second clamp head  265  to a position that allows it to clamp up to the TVRC of the distal end of drive shaft section  250  while air bags  270  and  271  are pressurized. The inflated air bags support the respective first and second clamp heads to the TVRC. It is understood, however, that forms of support other than air bags can be used in the practice of the invention. 
   During installation of drive shaft section  250  by the human operator, the drive shaft section is supported by a load support arrangement  280  that is provided in this specific illustrative embodiment of the invention with a pair of v-blocks  281  and  282  installed on a load support  284 . Load support  284  can be translated in the vertical direction by operation of a cylinder  288  that may be actuated by any known mode of actuation, such as electrical, pneumatic, or hydraulic. Thus, for example, after the human operator or robotic conveyor deposits drive shaft section  250  onto v-blocks  281  and  282 , load support  284  is raised to a position shown in phantom in the drawing and designated as load support  284 A, whereby coupling of the drive shaft section to chucks  260  and  265  is facilitated. At this point, in embodiments of the invention where clamp support arrangements  290  and  291  are not in the form of rigidly mounted spindles, as will be discussed in further detail below, load support  284  is lowered and chucks  260  and  265  are released to droop by deflating respectively associated air bags  270  and  271 . 
   In this specific illustrative embodiment of the invention, it is seen from  FIG. 10  that first and second clamp heads  261  and  265  are coupled to respective ones of clamp support arrangements  290  and  291 . Clamp support arrangements  290  and  291  are each pivotally coupled to respective base portions  294  and  295  at respective pivot couplings  298  and  299 . Such pivoting freedom of motion permits the arrangement to accommodate bends in drive shaft section  250 , but it is to be understood that such is not needed in embodiments of the invention where clamp support arrangements  290  and  291  are rigidly mounted. 
   It is to be noted that in this specific illustrative embodiment of the invention clamp support arrangements  290  and  291  are permitted an addition degree of freedom in the form of axial translation. This is represented in phantom in this figure as clamp support arrangements  290 A and  291 A. Rollers  302  and  303  are axially displaceable, as shown in phantom in the figure at roller positions  302 A and  303 A. Also, in some embodiments the rollers can be adjusted for offset, in addition to width, with respect to each other. It is to be understood, however, that in certain embodiments of the invention, clamp support arrangements  290  and  291  may be in the form of respective spindles that are rigidly mounted in a horizontal plane. In such an embodiment of the invention, chuck jaws  251  and  252  will permit articulation of the drive shaft as the lateral load is applied. 
   Upon completing the installation described hereinabove, drive shaft section  250  is rotated, as previously mentioned, and a ram  300  is then lowered, illustratively hydraulically by actuation of cylinder  301 , whereby rollers  302  and  303  are urged into axially transverse communication with drive shaft section  250  to effect the plastic deformation thereof, as previously described. During the truing operation, one of base portions  294  and  295  is permitted to travel axially, illustratively as a result of it being installed on axially-directed rails (not specifically identified), in order to accommodate variations in the effective length of drive shaft section  250  as it is deformed axially in response to the application of the transaxial force by rollers  302  and  303 . 
   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 invention claimed herein. 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.