Abstract:
A method for forming a propshaft assembly includes: providing a tube having an annular wall member and an axial end face; providing a yoke having body and a pair of arms that extend from the body, the body defining an annular groove having sidewalls and an end face, the sidewalls being spaced apart to receive the annular wall member; spinning at least one of the tube and the yoke while engaging the axial end face to the end face of the annular groove to plasticize a portion of the yoke and a portion of the tube; and driving the yoke and the tube together to fuse the plasticized portion of the yoke and the plasticized portion of the tube together and thereby form a friction weld; wherein the tube is fused to the yoke over portions of the yoke that correspond to the sidewalls and the end face.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No.  62 / 165 ,387 filed May 22, 2015, the disclosure of which is incorporated by reference as if fully set forth in detail herein. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a propshaft assembly having a yoke that is friction welded to a propshaft tube. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    Propshaft assemblies for cars and trucks typically are employed to transmit rotary power from an input device, such as a transmission or a transfer case, to an output device, such as an axle assembly. Commercial propshaft assemblies typically comprise a propshaft tube that is welded on one or more ends to a weld yoke. A common welding process for coupling the weld yoke(s) to the propshaft tube is friction welding. We have noted that it can be challenging to achieve sufficient weld strength when using relatively thin-walled tubing for the propshaft tube. 
       SUMMARY 
       [0005]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0006]    In one form, the present disclosure provides a method for forming a propshaft assembly. The method includes: providing a propshaft tube having an annular wall member and an axial end face; providing a weld yoke having yoke body and a pair of yoke arms that extend from the yoke body, the yoke body defining an annular groove having side walls and an end face, the side walls being spaced apart to receive the annular wall member; spinning at least one of the propshaft tube and the weld yoke while engaging the axial end face to the end face of the annular groove to plasticize a portion of the weld yoke and a portion of the propshaft tube; and driving the weld yoke and the propshaft tube together to fuse the plasticized portion of the weld yoke and the plasticized portion of the propshaft tube together and thereby form a friction weld; wherein the propshaft tube is fused to the weld yoke over portions of the weld yoke that correspond to the side walls and the end face. 
         [0007]    In one form, prior to driving the weld yoke and the propshaft tube together, a weld length control member is positioned around a portion of the propshaft tube and a portion of the yoke body in a location where the friction weld is to be formed and wherein the weld length control member is configured to limit migration of plasticized material from the plasticized portion of the propshaft tube in a radially outward direction. Optionally, the weld length control member can be part of the weld yoke or can be a tool that is independent of the propshaft assembly. 
         [0008]    In another form, the present disclosure provides a propshaft assembly that includes a propshaft tube and a weld yoke. The propshaft tube has a wall member. The weld yoke has a yoke body with an annular outer surface and an annular inner surface. The propshaft tube is welded to the yoke body such that a portion of the propshaft tube is disposed radially between the annular outer and inner surfaces and embedded into an axial end of the yoke body. 
         [0009]    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 
         [0010]    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. 
           [0011]      FIG. 1  is a schematic illustration of a propshaft assembly constructed in accordance with the teachings of the present disclosure, the propshaft assembly being illustrated in a drivetrain of an exemplary vehicle; 
           [0012]      FIG. 2  is a partly sectioned side elevation view of the propshaft assembly of  FIG. 1 ; 
           [0013]      FIG. 3  is an exploded perspective view of a portion of the propshaft assembly of  FIG. 1 ; 
           [0014]      FIG. 4  is a partly sectioned side elevation view of a portion of the propshaft assembly of  FIG. 1  illustrating a first yoke in more detail; 
           [0015]      FIG. 5  is a view similar to that of  FIG. 4  but illustrating an alternately constructed first yoke; 
           [0016]      FIG. 6  is a partly sectioned side elevation view depicting the locating of the first yoke relative to a propshaft tube and a tool prior to the formation of a friction weld that secures the first yoke to the propshaft tube as part of the process for manufacturing the propshaft assembly of  FIG. 1 ; 
           [0017]      FIG. 7  is a view similar to that of  FIG. 4  but illustrating yet another alternatively constructed first yoke; and 
           [0018]      FIG. 8  is a section view of a portion of the propshaft assembly of  FIG. 1  illustrating a weld zone that joins the first yoke to the propshaft tube. 
       
    
    
       [0019]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0020]    With reference to  FIG. 1 , a vehicle having a propshaft constructed in accordance with the teachings of the present disclosure is schematically illustrated. The vehicle  10  includes a power train  12  and a drivetrain  14 . The power train  12  can include a power source, such as an internal combustion engine  15 , and a transmission  16  that can cooperate to provide rotary power to the drivetrain  14 . The drivetrain  14  can include a propshaft assembly  20  and an axle assembly  22  that cooperate to transmit rotary power to a pair of drive wheels  24   a,    24   b.  The powertrain  12  and the axle assembly  22  can be conventional in their construction and operation and as such, a detailed discussion of these components need not be provided herein. The propshaft assembly  20  is configured to transmit rotary power between an output shaft  16   a  of the transmission  16  and an input pinion shaft  22   a  of the axle assembly  22 . 
         [0021]    With reference to  FIG. 2 , the propshaft assembly  20  can include a first universal joint  30 , a second universal joint  32  and a propshaft tube  34 . The propshaft tube  34  can be formed of a desired material, such as 6XXX or 5XXX aluminum alloys (e.g., 5454, 6061-T6) or steel. The propshaft tube  34  can be a seamless tubular structure (e.g., extrusion) or could be a welded tubular structure and can define an annular wall member  36 . 
         [0022]    With reference to  FIGS. 2 and 3 , the first and second universal joints  30  and  32  are generally similar and as such a discussion of the first universal joint  30  will suffice for both. The first universal joint  30  can have a first yoke  40 , a second yoke  42 , a cross-shaft  44  and a plurality of bearing assemblies  46 . The first yoke  40  can have a first yoke body  50  and a pair of first yoke arms  52  that extend from the first yoke body  50 . The first yoke body  50  is configured to be fixedly coupled to the first tubular member  34  with via friction welding as will be discussed in greater detail below. The first yoke arms  52  are spaced  180  degrees apart from one another around a rotational axis  54  of the first yoke  40 . Each of the first yoke arms  52  defines a bore  56  that is configured to receive an associated one of the bearings assemblies  46  therein. 
         [0023]    The second yoke  42  can have a second yoke body  60  and a pair of second yoke arms  62  that extend from the second yoke body  60 . The second yoke body  60  is configured to be axially and non-rotatably coupled to the input pinion shaft  22   a  ( FIG. 1 ) in a desired manner, such as with a plurality of bolts (not shown). Alternatively, the second yoke body  60  could be configured as a slip yoke that could be configured to be non-rotatably but axially slidably coupled to a power transmitting element, for example in the manner shown for the second universal joint  32 . The second yoke arms  62  are spaced 180 degrees apart from one another around a rotational axis  64  of the second yoke  42 . Each of the second yoke arms  62  defines a bore  66  that is configured to receive an associated one of the bearing assemblies  46  therein. 
         [0024]    The cross-shaft  44  defines a pair of first trunnions  70 , which are received into the bores  56  in the first yoke arms  52 , and a pair of second trunnions  72  that are received into the bores  66  of the second yoke arms  62 . Each of the bearing assemblies  46  comprises a bearing cup  80 , which is engaged to a corresponding one of the first and second yoke arms  52  and  62 , and a plurality of rollers  82  that are disposed between the bearing cup  80  and a corresponding one of the first and second trunnions  70  and  72 . Accordingly, it will be appreciated that each of the first trunnions  70  is pivotally mounted to a corresponding one of the first yoke arms  52  and that each of the second trunnions  72  is pivotally mounted to a corresponding one of the second yoke arms  62 . 
         [0025]    With reference to  FIG. 4 , the first yoke  40  can be unitarily formed from a suitable material that is friction weld-compatible with the material from which the propshaft tube  34  ( FIG. 2 ) is formed, such as 6061-T6 aluminum. The first yoke body  50  can have an annular wall  90  that can define an outer circumferential surface  92 , an inner circumferential surface  94  and an annular groove  96  that is disposed between the outer and inner circumferential surfaces  92  and  94 . The annular groove  96  can have a pair of sidewalls  100  and an end face  102 . Alternatively, the first yoke  40  could be an assembly that can include a first yoke portion  110  and a second yoke portion  102 . The first yoke portion  110  can define a bore  116  into which the second yoke portion  112  is fitted. The second yoke portion  112  can be fixedly coupled to the first yoke portion  110  by any desired means, such as welding. The second yoke portion  112  can at least partly define the annular groove  96 . In the particular example provided, the second yoke portion  112  defines a first one of the sidewalls  100   a  and the end face  102 , while the inside surface of the bore  116  in the first yoke portion  110  can define the remaining sidewall  100   b.    
         [0026]    With reference to  FIG. 6 , the annular groove  96  can be sized to receive or partly receive the annular wall member  36  of the propshaft tube  34 . In the particular example provided the annular groove  96  has a width (between the sidewalls  100 ) of about 0.050 inch (1.27 mm) and the annular wall member  36  has a thickness of about 0.075 inch (1.90 mm) to 0.120 inch (3.05 mm) so that there is an interference of about 0.025 inch (0.64 mm) to 0.070 inch (1.78 mm) between the propshaft tube  34  and the first yoke body  50 . It will be appreciated, however, that the sidewalls  100  could be spaced apart by a distance that is sufficient to wholly admit the wall thickness of the propshaft tube  34 . The annular groove  96  can have a desired depth, such as a depth of about 0.160 inch (4.0 mm). In practice, we have found that the wall thickness of the portion of the first yoke body  50  that is disposed between the outer circumferential surface of the first yoke body  50  and the outer one of the sidewalls  100  can be thicker than the wall thickness of the annular wall member  36  by a desired amount, such as by about twenty percent (20%). At least one of the propshaft tube  34  and the first yoke  40  can be spun while an axial face  130  of the annular wall member  36  is abutted to the end face  102  of the annular groove  96 . Frictional contact between the axial end face  130  and the end face  102  of the annular groove  96  can generate heat that can plasticize a portion of the first yoke body  50  and a portion of the propshaft tube  34 . The first yoke  40  and the propshaft tube  34  can be driven together to fuse the first yoke  40  and the propshaft tube  34  together. 
         [0027]    If desired, a tool  136  can be employed during the friction welding process to limit the maximum diameter of the resulting weld (i.e., the tool  136  can function as a weld length control member). In the example provided, the tool  136  is configured to limit migration of the plasticized material of the first yoke body  50  in a radially outward direction by urging the plasticized material of the first yoke body  50  in an axial direction along the rotational axis  54  of the first yoke  40  to thereby extend a length of the resulting friction weld along the outer circumferential surface  140  of the propshaft tube  34 . It should be appreciated, however, that the weld length control member  136   a  could be incorporated into the first yoke body  50   a  as shown in  FIG. 7 . In this example, the weld length control member  136   a  comprises an extension of the portion of the first yoke body  50   a  that defines the portion of the first yoke body  50   a  that defines the radially outer sidewall  100  of the annular groove  96 . 
         [0028]    In  FIG. 8 , a portion of the friction weld that fixedly couples the propshaft tube  34  to the first yoke  40  is illustrated. As shown, the propshaft tube  34  is welded to the first yoke body  50  such that a portion  150  of the propshaft tube  34  is disposed radially between the outer and inner circumferential surfaces  92  and  94  of the first yoke body  50  and the portion  150  of the propshaft tube  34  is embedded into an axial end of the first yoke body  50 . In this regard, the friction weld defines a weld zone  156  having a radial component, in which the axial end face  130  of the propshaft tube  34  had abutted the end face  102  of the annular groove  96  in the first yoke body  50 , as well as components that extend axially along the outer circumferential surface  140  and inner circumferential surface  160  of the propshaft tube  34 . Configuration in this manner permits the weld zone  156  to be formed over a longer span as compared to the weld zone of a conventional friction weld, which would substantially conform to a cylindrical shape. Consequently, the weld zone  156  that is created with the present process can be significantly stronger than a conventional friction weld and can permit the wall thickness of the propshaft tube  34  to be decreased. 
         [0029]    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.