Abstract:
A method for assembling a propshaft assembly. The method can include: providing a tubular member, the tubular member having an annular wall with an inside circumferential surface; pushing a first ram through the tubular member; loading a damper between the first ram and a second ram; twisting the damper between the first and second rams; moving the first and second rams to translate the twisted damper into the tubular member; untwisting the damper in the tubular member; and withdrawing the first and second rams from the tubular member. A machine for assembling a propshaft assembly is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/904,129 filed Nov. 14, 2013, the disclosure of which is incorporated by reference as if fully set forth in detail herein. 
    
    
     FIELD 
     The present disclosure relates to a method and a machine for assembling a propshaft assembly. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     The consumers of modern automotive vehicles are increasingly influenced in their purchasing decisions and in their opinions of the quality of a vehicle by their satisfaction with the vehicle&#39;s sound quality. In this regard, consumers increasingly expect the interior of the vehicle to be quiet and free of noise from the power train and drive line. Consequently, vehicle manufacturers and their suppliers are under constant pressure to reduce noise to meet the increasingly stringent expectations of consumers. 
     Drive line components and their integration into a vehicle typically play a significant role in sound quality of a vehicle as they can provide the forcing function that excites specific driveline, suspension and body resonances to produce noise. Since this noise can be tonal in nature, it is usually readily detected by the occupants of a vehicle regardless of other noise levels. Common driveline excitation sources can include driveline imbalance and/or run-out, fluctuations in engine torque, engine idle shake, and motion variation in the meshing gear teeth of the hypoid gear set (i.e., the pinion gear and the ring gear of a differential assembly). 
     Propshafts are typically employed to transmit rotary power in a drive line. Modern automotive propshafts are commonly formed of relatively thin-walled steel or aluminum tubing and as such, can be receptive to various driveline excitation sources. The various excitation sources can typically cause the propshaft to vibrate in a bending (lateral) mode, a torsion mode and a shell mode. Bending mode vibration is a phenomenon wherein energy is transmitted longitudinally along the shaft and causes the shaft to bend at one or more locations. Torsion mode vibration is a phenomenon wherein energy is transmitted tangentially through the shaft and causes the shaft to twist. Shell mode vibration is a phenomenon wherein a standing wave is transmitted circumferentially about the shaft and causes the cross-section of the shaft to deflect or bend along one or more axes. 
     Several techniques have been employed to attenuate vibrations in propshafts including the use of foam inserts. U.S. Pat. No. 6,752,722 to Armitage, et al. for example discloses the use of a pair of foam insert members that are inserted into a propshaft tube and located at the second bending mode anti-nodes. It is known in the art to employ a vacuum to install form inserts into a propshaft tube. The installation of the foam insert(s) into a propshaft tube can be time consuming and may not be capable of locating the foam insert(s) in as precise a manner as desired. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In one form, the present teachings provide a method for assembling a propshaft assembly. The method can include: providing a tubular member, the tubular member having an annular wall with an inside circumferential surface; pushing a first ram through the tubular member; loading a damper between the first ram and a second ram; twisting the damper between the first and second rams; moving the first and second rams to translate the twisted damper into the tubular member; untwisting the damper in the tubular member; and withdrawing the first and second rams from the tubular member. 
     In another form, the present teachings provide a propshaft assembly machine that includes a tube holder, a headstock, a tailstock and a controller. The tube holder is configured to hold the tubular member such that a longitudinal axis of the tubular member is coincident with a central axis. The headstock has a first ram that is movable along the central axis. The tailstock has a second ram that is movable along the central axis. The controller is configured to coordinate movement of the first and second rams. At least one of the first and second rams is rotatable about the central axis to cause the damper to be twisted between the first and second rams. The controller can coordinate translation of the first and second rams to cause the damper to be installed into the tubular member. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a schematic illustration of an exemplary vehicle having a propshaft assembly constructed in accordance with the teachings of the present disclosure; 
         FIG. 2  is a top partially cut-away view of a portion of the vehicle of  FIG. 1  illustrating a rear axle and the propshaft assembly in greater detail; 
         FIG. 3  is a sectional view of a portion of the rear axle and the propshaft assembly; 
         FIG. 4  is a top, partially cut away view of the propshaft assembly; 
         FIG. 5  is a schematic view of an assembly machine that is configured to compress a damper and install the damper to a tubular member of the propshaft assembly in accordance with the teachings of the present disclosure; and 
         FIG. 6  is schematic view in flow-chart form of an exemplary method for assembling a propshaft assembly in accordance with the teachings of the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     With reference to  FIG. 1  of the drawings, an exemplary vehicle constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral  10 . The vehicle  10  can include an engine  14  and a drive line  16 . The drive line  16  can include a transmission  18 , a propshaft assembly  20 , a rear axle  22  and a plurality of wheels  24 . The engine  14  can produce rotary power that can be transmitted to the transmission  18  in a conventional and well known manner. The transmission  18  can be conventionally configured and can include a transmission output shaft  18   a  and a gear reduction unit (not specifically shown). As is well known in the art, the gear reduction unit can change the speed and torque of the rotary power provided by the engine such that a rotary output of the transmission  18  (which can be transmitted through the transmission output shaft  18   a ) can have a relatively lower speed and higher torque than that which was input to the transmission  18 . The propshaft assembly  20  can be coupled for rotation with the transmission output member  18   a  to permit drive torque to be transmitted from the transmission  18  to the rear axle  22  where can be selectively apportioned in a predetermined manner to the left and right rear wheels  24   a  and  24   b , respectively. 
     It will be appreciated that while the vehicle in the particular example provided employs a drive line with a rear-wheel drive arrangement, the teachings of the present disclosure have broader applicability. In this regard, a shaft assembly constructed in accordance with the teachings of the present disclosure may interconnect a first drive line component with a second drive line component to transmit torque therebetween. In the context of an automotive vehicle, the drive line components could be a transmission, a transfer case, a viscous coupling, an axle assembly, or a differential, for example. 
     With reference to  FIG. 2 , the rear axle  22  can include a differential assembly  30 , a left axle shaft assembly  32  and a right axle shaft assembly  34 . The differential assembly  30  can include a housing  40 , a differential unit  42  and an input shaft assembly  44 . The housing  40  can support the differential unit  42  for rotation about a first axis  46  and can further support the input shaft assembly  44  for rotation about a second axis  48  that is perpendicular to the first axis  46 . 
     With additional reference to  FIG. 3 , the housing  40  can be formed in a suitable casting process and thereafter machined as required. The housing  40  can include a wall member  50  that can define a central cavity  52  that can have a left axle aperture  54 , a right axle aperture  56 , and an input shaft aperture  58 . The differential unit  42  can be disposed within the central cavity  52  of the housing  40  and can include a case  70 , a ring gear  72 , which can be fixed for rotation with the case  70 , and a gearset  74  that can be disposed within the case  70 . The gearset  74  can include first and second side gears  82  and  86  and a plurality of differential pinions  88 , which can be rotatably supported on pinion shafts  90  that can be mounted to the case  70 . The case  70  can include a pair of trunnions  92  and  96  and a gear cavity  98 . A pair of bearing assemblies  102  and  106  can support the trunnions  92  and  96 , respectively, for rotation about the first axis  46 . The left and right axle assemblies  32  and  34  can extend through the left and right axle apertures  54  and  56 , respectively, where they can be coupled for rotation about the first axis  46  with the first and second side gears  82  and  86 , respectively. The case  70  can be operable for supporting the plurality of differential pinions  88  for rotation within the gear cavity  98  about one or more axes that can be perpendicular to the first axis  46 . The first and second side gears  82  and  86  each include a plurality of teeth  108  which meshingly engage teeth  110  that are formed on the differential pinions  88 . 
     The input shaft assembly  44  can extend through the input shaft aperture  58  where it can be supported in the housing  40  for rotation about the second axis  48 . The input shaft assembly  44  can include an input shaft  120 , a pinion gear  122  having a plurality of pinion teeth  124  that meshingly engage the teeth  126  that are formed on the ring gear  72 , and a pair of bearing assemblies  128  and  130  that can cooperate with the housing  40  to rotatably support the input shaft  120 . The input shaft assembly  44  can be coupled for rotation with the propshaft assembly  20  and can be operable for transmitting drive torque to the differential unit  42 . More specifically, drive torque received the input shaft  120  can be transmitted by the pinion teeth  124  to the teeth  126  of the ring gear  72  such that drive torque is distributed through the differential pinions  88  to the first and second side gears  82  and  86 . 
     The left and right axle shaft assemblies  32  and  34  can include an axle tube  150  that can be fixed to the associated axle aperture  54  and  56 , respectively, and an axle half-shaft  152  that can be supported for rotation in the axle tube  150  about the first axis  46 . Each of the axle half-shafts  152  can include an externally splined portion  154  that can meshingly engage a mating internally splined portion (not specifically shown) that can be formed into the first and second side gears  82  and  86 , respectively. 
     With reference to  FIG. 4 , the propshaft assembly  20  can include a tubular member  200 , a first end connection  202   a , a second end connection  202   b , and a damper  204 . The tubular member and the first and second end connections  202   a  and  202   b  can be conventional in their construction and need not be described in significant detail herein. Briefly, the tubular member  200  can be formed of an appropriate structural material, such as steel or aluminum, and can include an annular wall member  224 . The annular wall member  224  can have an interior circumferential surface  228  and can define a hollow cavity  230 . Depending on the particular requirements of the vehicle  10  ( FIG. 1 ), the wall member  224  may be sized in a uniform manner over its entire length, as is shown in  FIG. 4 , or may be necked down or stepped in diameter in one or more areas along its length. The first and second end connections  202   a  and  202   b  can be configured to couple the propshaft assembly  20  to other rotary components of the vehicle  10  ( FIG. 1 ) in a desired manner to transmit rotary power therebetween. For example, the first end connection  202   a  and/or the second end connection  202   b  could comprise a universal joint (e.g., Cardan or constant velocity joint) or components thereof that can be fixedly coupled to the tubular member  200 . For example, the first and second end connections  202   a  and  202   b  could comprise weld yokes that are welded to the opposite ends of the tubular member  200 . Optionally, one or both of the first and second end connections  202   a  and  202   b  can be vented to permit air to flow into or out of the hollow cavity  230 . In the particular example provided, a vent  232  is installed to each of the first and second end connections  202   a  and  202   b . In the particular example provided, the vents  232  comprise holes formed in the first and second end connections  202   a  and  202   b , but it will be appreciated that the vent(s)  232  can be constructed in any desired manner. 
     The damper  204  can be effective in attenuating shell mode vibration transmitted through the tubular member  200 , but may also be effective in attenuating other vibration modes, such as torsion mode vibration and/or bending mode vibration through the tubular member  200 . Shell mode vibration, also known as breathing mode vibration, is a phenomenon wherein a standing wave is transmitted circumferentially about the tubular member  200  and causes the cross-section of the shaft to deflect (e.g., expand or contract) and/or bend along one or more axes. Torsion mode vibration is a phenomenon wherein energy is transmitted tangentially through the shaft and causes the shaft to twist. Bending mode vibration is a phenomenon wherein energy is transmitted longitudinally along the shaft and causes the shaft to bend at one or more locations. 
     The damper  204  can be formed of a suitable damping material, such as a length of foam or other compressible but resilient material. In the particular example provided, the damper  204  is a length of a cylindrically-shaped closed-cell foam that can be formed of a suitable material. Examples of suitable materials include polyethylene; polyurethane; sponge rubber; PVC and vinyl nitrile blends; PP and nylon foam blends; and melamine, polyimide and silicone. It will be appreciated that various other materials, such as an open-cell foam, or that one or more apertures could be formed longitudinally through the damper  204 . 
     The damper  204  can have an appropriate density, such as between 1.0 pounds per cubic foot to 2.5 pounds per cubic foot, preferably between 1.2 pounds per cubic foot to about 1.8 pounds per cubic foot, and more preferably between 1.20 pounds per cubic foot to 1.60 pounds per cubic foot. In the particular example provided, the damper  204  has a density of 1.45 pounds per cubic foot. The damper  204  can be sized in a manner so that it is compressed against the inside circumferential surface  228  of the tubular member  200  to a desired degree. For example, the damper  204  can have an outer circumferential diameter that is about 5% to about 20% larger than the diameter of the inside circumferential surface  228  of the tubular member  200 , and more preferably about 10% larger than the diameter of the inside circumferential surface  228  of the tubular member  200 . 
     The damper  204  can be tuned for a particular vehicle configuration in part by altering one or more characteristics of the damper  204 , such as its position relative to the tubular member  200 , its length, etc. In the particular example provided, damper is disposed in the middle of the tubular member  200 . 
     The damper  204  can be installed to the tubular member  200  by pre-compressing the damper  204  and then sliding the (compressed) damper  204  into the tubular member  200  such that it is positioned relative to the tubular member in a desired manner. Any means may be employed to compress the damper  204  prior to its insertion into the tubular member  200 . In the particular example provided, the damper  204  compressed is twisted to achieve the desired level of compression. 
     With reference to  FIG. 5 , an exemplary assembly tool  500  for inserting the damper  204  into the tubular member  200  is illustrated. The assembly tool  500  may be procured from the Cardinal Machine Company of Clio, Mich. The assembly tool  500  can include a base  502 , a headstock  504 , a tailstock  506 , a damper holder  508 , a tube holder  510  and a control system  512 . The base  502  can be a suitably configured structure to which the headstock  504 , the tailstock  506 , the damper holder  508  and the tube holder  510  are mounted or coupled. The headstock  504  can include a first ram  520  and a first ram movement mechanism  522  that permits the first ram  520  to be moved in an axial direction along a central axis  524  that is defined by the base  502 . The first ram movement mechanism  522  can also permit the first ram  520  to be rotated about the central axis  524 . The first ram  520  can include a first end effector  526  that is configured to engage the damper  204  as will be discussed in further detail below. 
     The tailstock  506  can include a second ram  530  and a second ram movement mechanism  532  that can permit the second ram  530  to be moved in an axial direction along the central axis  524  and rotated about the central axis  524 . It will be appreciated that one or both of the first and second rams  520  and  530  may be configured to be driven (by the first and second ram movement mechanisms  522  and  532 , respectively) about the central axis  524 . The second ram  530  can include a second end effector  536  that is configured to engage the damper  204  as will be discussed in further detail below. 
     The damper holder  508  can be configured to hold the damper  204  prior to its insertion into the tubular member  200 , as well as locate or position the damper  204  relative to the tubular member  200  prior to its insertion into the tubular member  200 . The damper holder  508  could comprise any suitable structure, such as a pair of rollers that are mounted to the base  502 . In the particular example provided, the damper holder  508  comprises at least a portion of a tubular shell that is configured to cradle the damper  204 , as well as to orient the damper  204  such that its longitudinal axis is coincident with the central axis  524 . The damper holder  508  can be positioned axially between the headstock  504  and the tailstock  506 . 
     The tube holder  510  can be configured to hold the tubular member  200  prior to and during the assembly process so that a longitudinal axis of the tubular member  200  is coincident with the central axis  524  and the tubular member  200  is position along the central axis  524  in an accurate and repeatable manner. For example, the tube holder  510  can comprise a set of rollers or a portion of a tubular shell  540 , which can be coupled to the base  502 , a clamping member  542 , which can clamp the tubular member  200  against the rollers or tubular shell to inhibit movement of the tubular member  200  relative to the tube holder  510 , and a stop member  546  that is fixedly coupled to the base  502 . The tubular member  200  can be slid on the tube holder  510  and abutted against the stop member  546  to position the tubular member  200  in a known manner relative to the base  502 . 
     The control system  512  can include a controller  550  that can coordinate the operation of the first and second ram movement mechanisms  522  and  532 . 
     With additional reference to  FIG. 6 , which schematically depicts an exemplary assembly method, the control can proceed to block  600  where the tubular member  200  to the loaded to the tube holder  510 . It will be appreciated that the loading of the tubular member  200  to the tube holder  510  can additionally comprise abutting the tubular member  200  to the stop member  546  and clamping or otherwise securing the tubular member  200  to the tube holder  510  to resist axial movement of the tubular member  200  along the central axis  524 . Control can proceed to block  604 . 
     In block  604 , the damper  204  can be loaded to the damper holder  508  to align the damper to the central axis  524  and optionally to locate or position the damper  204  relative to another structure, such as the base  502  or the tubular member  200 . Control can proceed to block  608 . 
     In block  608 , control can operate the first and second ram movement mechanisms  522  and  532  such that the first and second end effectors  526  and  536  engage the opposite ends of the damper  204 . It will be appreciated that the first ram  520  must extend through the tubular member  200  to engage the damper  204 . The first and second end effectors  526  and  536  could be configured with tines or forks to engage the ends of the damper  204 , or could be configured to clamp (and compress) the opposite ends of the damper  204 . It may be desirable to support one or both of the first and second rams  520  and  530  and/or one or both of the first and second end effectors  526  and  536  prior to engagement of the first and second end effectors  526  and  536  with the damper  204 . In the particular example provided, a support  610  is provided between the tubular member  200  and the damper  204  to support the first ram  520  when the first end effector  526  is initially positioned proximate the damper  204 . The support  610  can comprise any type of structure, such as a plate or rollers, but in the particular example provided, comprises a V-block that is mounted on a pneumatic cylinder (not specifically shown) that is mounted to the base  502 . The V-block can be normally positioned in a lowered position, which permits the end effector  526  to pass between the tube holder  510  and the damper holder  508 , but can be raised to support the distal end of the first ram  520  to ensure alignment of the longitudinal axis of the first ram  520  to the central axis  524 . In practice, it may be beneficial to have the V-block engage a positive stop that is mounted in an adjustable manner to the base  502  when the V-block is raised to ensure that the desired alignment between the longitudinal axis of the first ram  520  and the central axis  524  is achieved. Those of skill in the art will appreciate that a similar support (not shown) could be provided to directly support the second ram  530  and/or the second end effector  536 . Control can proceed to block  612 . 
     In block  612 , control can operate one or both of the first and second ram movement mechanisms  522  and  532  to twist the damper  204  to a point where the outside diameter of the damper  204  is smaller than the inside diameter of the annular wall member  224  ( FIG. 4 ) that forms the tubular member  200 . In the particular example provided, the damper  204  is twisted to reduce its outside diameter from about 6.38 inches (162 mm) to about 4.0 inches (102 mm). Control can proceed to block  616 . 
     In block  616 , control can operate the first and second ram movement mechanisms  522  and  532  to translate the (twisted) damper  204  along the central axis  524  and position the damper  204  along the length of the tubular member  200  in a desired manner. Control can proceed to block  620 . 
     In block  620 , control can operate one or both of the first and second ram movement mechanisms  522  and  532  to untwist the damper  204  and to thereafter release the damper  204  and withdraw the rams  520  and  530  from the tubular member  200 . Once untwisted, the damper  204  will expand and engage the inner circumferential surface  228  ( FIG. 4 ) of the annular wall member  224  ( FIG. 4 ). Control can proceed to block  624  where the tubular member  200  can be unclamped or released from the tube holder  510  and the intermediate assembly, which consists of the damper  204  installed to the tubular member  200 , can be removed from the assembly tool  500 . Control can proceed to block  628 , where the first and second end connections  202   a  and  202   b  ( FIG. 4 ) can be coupled to respective ends of the tubular member  200  to form the propshaft assembly  20  ( FIG. 4 ). Control can proceed to bubble  632 , where control can terminate. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.