Abstract:
A panel structure includes panel members that may be connected together using friction stir welding, Each of the panel members includes a first plate, a second plate substantially in parallel to said first plate, and at least one webbing member connecting the first plate and the second plate. The first plate of the first panel member includes a flange positioned in abutment with a flange located on the first plate of the second panel member. The flange of the first panel member includes a projection and the flange of the second panel member includes a groove. The panel members are connected so that the projection is engaged with the groove to thereby resist relative lateral movement that would separate the panel members.

Description:
[0001]    The present application relates generally to structures and methods for structural members including, for example, panels such as panel members that are joined through various methods including, for example, fusion welding, friction stir welding, and mechanical fastening applications. 
         [0002]    A panel type structural member may be formed by connecting structural members. The connected members form a panel that includes two generally parallel plates. The plates may be spaced vertically apart by internal vertical, slanted, trapezoidal, or triangular members similar in nature to the way webbing spaces two horizontal surfaces in I-beams. The internal webbing or ribbing serves to distribute loads imparted on the horizontal surfaces of the panels. Additionally, the webbing rigidly resists deflection and torsion resulting from the loads imparted on the horizontal panels. 
         [0003]    Creating structural panels from lightweight metals, such as aluminum, is advantageous for several reasons. Decreasing the weight of the panel in a structure may allow for increased loading on the panel and assembled structure. Aluminum panels can be prefabricated in modular units and joined together on site when placed in service. Aluminum panels are more easily transported than heavier metals or preformed concrete. Aluminum panels may be employed in new structures, or the panels may be used to refurbish an aging structure. 
         [0004]    Modular panels may be joined at their vertical seam abutments by various welding, filling, or fastening methods. Welding the panel faying surfaces (abutments) typically provides for more rigidity and increased load distribution, whereas non-welded fasteners allow enhanced and semi or fully-independent movement as between modular panels under changing load conditions. In applications where welded joints are desired, the use of friction stir welding (“FSW”) techniques has developed as one possible method for joining the panel members. 
         [0005]    Friction stir welding generally includes the application of a pin or probe to the surface of a joint or seam. The pin applies pressure and friction, typically by spinning, on the seam sufficient to cause the metal of the faying surface to plasticize. The pin may be separately heated, but typically is designed to cause the metal to plasticize purely as a result of pressure without the need for additional heat or electricity. The pin moves along the length of the faying surface, and the plasticized metals from adjoining members are effectively “stirred” and intermix in the void created by the pin movement, thereby creating a weld seam. 
         [0006]    Additionally, traditional FSW processes impart not only axial forces normal to the plane of the abutment flanges, but FSW effectively imparts lateral forces as well. The surfaces of the structural members to be welded are generally positioned adjacent to each other using simple square butt weld joints or simple overlap joints. When an FSW pin imparts pressure on the structural members being welded, these members may be forced away from each other. The type of joints currently employed in these structural members provide no resistance to lateral separation during the welding process. As a result, conventional processes require the use of significant clamping forces to ensure that the structural members do not separate laterally during the welding process. 
         [0007]    Accordingly, a need exists for a structure and method for joining panel members for assembly using FSW techniques. 
       SUMMARY 
       [0008]    As described below, a panel structure that is adapted to be friction stir welded is disclosed herein. The structure includes a first panel member arranged against a second panel member. Each of the first and second panel members includes a first plate, a second plate substantially in parallel to said first plate, and at least one webbing member connecting the first plate and the second plate. The first plate of the first panel member includes a flange positioned in abutment with a flange located on the first plate of the second panel member. The flange of the first panel member includes a projection and wherein the flange of the second panel member includes a groove. The panel members are connected so that the projection is engaged with the groove to thereby resist relative lateral movement that would separate the panel members. 
         [0009]    A panel structure including structural members connected together by a friction stir welding process is disclosed herein. The structure includes first and second panel members that include top and bottom plates connected together by a plurality of ribs. The top plates of the first and second panel members are connected together using friction stir welding. The top plate of the first panel member includes a projection that fits in a recess located in the top plate of the second panel member to thereby resist lateral separation of the panel members in response to forces applied to the panel members during the friction stir welding process. 
         [0010]    A method of making a panel the structure is also disclosed. The method includes the step of providing first and second panel members, wherein each of the panel members includes a first plate, a second plate substantially in parallel to said first plate, and at least one webbing member connecting the first plate and the second plate. According to the method, the panel members are positioned so that a flange located on the first plate of the first panel abuts a flange located on the first plate of the second panel member. The positioning step includes positioning a projection located on the flange of the first panel member into engagement with a groove located on the flange of the second panel member to thereby resist relative lateral movement that would separate the panel members. The first and second panel members using a friction stir welding process. 
         [0011]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a vertical elevation view of a portion of a panel structure showing several panel members connected together at abutment joints. 
           [0013]      FIG. 2  is an exemplary vertical elevation view of abutment joints between adjacent panel members. 
           [0014]      FIG. 3  is an exemplary vertical elevation view of an FSW pin being applied to the surface of an upper plate of an abutment joint in a panel with an anvil beneath the upper surface. 
           [0015]      FIG. 4  is an exemplary vertical elevation view of exemplary abutment joints between adjacent panel members. 
           [0016]      FIG. 5  is a close up elevated view of the abutment joint shown in region A of  FIG. 4 . 
           [0017]      FIG. 6  is an exemplary vertical elevation view of exemplary abutment joints between adjacent members. 
           [0018]      FIG. 7  is a close up elevated view of the abutment joint shown in region B of  FIG. 6 . 
           [0019]      FIG. 8  is an exemplary vertical elevation view of exemplary abutment joints between adjacent panel members. 
           [0020]      FIG. 9  is an exemplary vertical elevation view of exemplary abutment joints between adjacent panel members. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The structure and methods described herein for automatically aligning panel members for FSW applications can now be better understood turning to the following detailed description. It is to be understood that the illustrated embodiments are set forth as examples and not intended to limit the scope of the claims. 
         [0022]      FIG. 1  discloses an end view of a portion of a panel structure including several connected structural members. Each of the structural members is aligned together using abutment joints and may preferably be welded together using, for example, a FSW process. As shown in  FIG. 1 , a first panel member  12  and a second panel member  14  are positioned adjacent to each other. Each member  12 ,  14  includes an upper plate  11  and a lower plate  15 . The plates are connected together by internal walls, webbing or ribs  13  that separate the upper plate  11  to the lower plate  15 . The internal webbing  13  may extend vertically or at an angle as between upper and lower plates  11 ,  15 . 
         [0023]    The lateral edges of the upper and lower plates  11 ,  15  that abut another panel member include flanges. The flanges may be configured as either male or female projections. As shown in  FIG. 1 , one structural member  12  includes female flanges  81 ,  82  at both lateral edges including the top and bottom panels. The adjacent structural member  14  includes male flanges  83 ,  84  at one lateral edge and female flanges  81 ,  82  at the opposite lateral edge. The configuration of the structural members  12 ,  14  may be varied depending on the configuration. For example, a structural member may be configured to include a female/female flange configuration as depicted by the structural member  12  shown in  FIG. 1 . However, male/male and male/female configurations are also suitable depending on the project being assembled. Also, the flange used on the upper and lower plate can be varied between the male/female configuration so that the flange present on the upper plate  11  does not necessarily have to match the flange configuration present on the lower plate  15 . 
         [0024]    The flange configurations depicted in  FIG. 1  may be varied. For example, either or both of the upper and lower flanges may be configured as simply a blunt vertical surface. Each blunt vertical surface of each respective upper and lower flange would be positioned to be in contact prior to the using a FSW process to secure the structural members together. As shown in  FIGS. 2 and 3 , either the mated flanges or blunt flanges may be used in the connection between the structural members shown in  FIG. 1 . 
         [0025]      FIG. 3  is an exemplary vertical elevation view of the application of an FSW pin  32  to upper panels of two panel members. As used herein, the blunt vertical surfaces  24  of each upper and lower flange  16 ,  20  may also be referred to as faying surfaces  24 , or collectively, abutment joint  24 . The panel members may be connected using an FSW tool  30  that is applied to weld together the adjacent surfaces  24  of the upper and lower flanges  16 ,  20 . Once welding is complete, and the panel members are permanently connected, the joined region may be referred to as a weld line  24 . As shown in  FIG. 3 , an FSW tool  30  comprises a pin  32  which imparts vertical and rotational frictional pressure on the faying surface  24  of the upper flange  16  of each panel member  12 ,  14 . In order to counteract the vertical pressure of the FSW tool  30 , an anvil  34  may be temporarily placed beneath the upper flanges  16  of each panel member  12 ,  14 . The anvil  34  further distributes the vertical pressure from the FSW tool  30  to the lower panels  15  of each panel member  12 ,  14  and thereon to any surface by which the members  12 , 14  are supported (not depicted). In application, the members  12 ,  14  and the FSW tool  30  must move in opposite directions relative to one another. Effectively, the FSW tool traverses across the members  12 ,  14 . In the embodiment of  FIG. 2 , for example, the FSW tool  30  moves along the path of the faying surface  24  in the direction of the extrusion profile. 
         [0026]    In the FSW process shown in  FIG. 3 , a second FSW tool  30  may be used to join the faying surfaces  24  of the lower flanges  20 . It may also be possible to articulate the FSW tool  30  to a location beneath the members  12 ,  14 . Alternatively, the panel members  12 ,  14  may be repositioned so that the lower plate and abutment joint is located at the top of the panel and the FSW tool  30  can be reapplied. 
         [0027]    During the FSW process described above, there is a tendency for the adjacent panel members  12 ,  14  to be forced laterally apart. In order to hold the panel members  12 ,  14  together until the welding process is complete, laterally clamping forces may be applied. Thus, the FSW welding apparatus must be provided with a lateral clamping mechanism for holding the panel members  12 ,  14  in position by applying a lateral force from one or more directions to force and hold the panel members  12 ,  14  in position to be welded. In certain FSW processes, it may also be desirable to include a vertical clamping mechanism to prevent bowing of the panel members  12 ,  14 . The need to provide clamping mechanisms (e.g., a hydraulic clamp) adds to the complexity and cost of the FSW process. Therefore, there is a need to improve the FSW process for connecting panel members to eliminate or reduce the forces required to hold the panel members in position during welding. In addition, various problems occur as a result of the manufacturing extrusion process, which can make it difficult to employ typical FSW methods to panel members. Thus, a self-aligning structure, such as disclosed herein, is needed for the enhanced consistency of FSW welding applications to join structural panel.  FIGS. 4-9  disclose alternative embodiments that provide for improved panel structure. 
         [0028]      FIGS. 4 and 5  disclose views of a pair of panel members  140 ,  120  connected together prior to the commencement of the FSW process. As shown in the exemplary arrangement of  FIG. 4 , the second panel member  140  includes a supporting web  130  and two connection flanges configured in a male configuration. The structural elements disclosed herein are referred to as panel members, and the term panel is intended to encompass a planar surface whether vertical, horizontal or other orientation. The first panel member  120  includes female configured flanges at the top and bottom plates. As shown in  FIG. 4 , the top plate of the first panel member  120  may include a female configured flange  124  that mates with a male configured flange  144  of the second panel member  140 . As shown in  FIG. 5 , the abutting connection between the top plates of the first and second panel members  120 ,  140  includes a tongue and groove arrangement. For example, the second panel member  140  may include a male configured flange that includes a downwardly projecting protrusion  142  that fits in a complementary groove or recess  122  located in the first panel member  124 . As shown in  FIG. 5 , the protrusion  142  is angular and tooth shaped. The ramped surface of the protrusion  142  facing the first panel member  120  facilitates the process for connecting the first and second panel members  120 ,  140 . 
         [0029]      FIGS. 6 and 7  disclose another alternative embodiment of configuration for connecting panel members. The first panel member  120  includes female configured flanges at the top and bottom plates. As shown in  FIG. 6 , the bottom plate of the first panel member  120  may include a female configured flange  124  that mates with a male configured flange  144  of the second panel member  140 . As shown in  FIG. 6 , the abutting connection between the top plates of the first and second panel members  120 ,  140  includes a tongue and groove arrangement. For example, the second panel member  140  may include a male configured flange that includes a downwardly projecting protrusion  143  that fits in a complementary groove or recess  123  located in the first panel member  124 . As shown in  FIG. 7 , the protrusion  143  is curved, preferably rounded. The curved surface of the protrusion  143  facing the first panel member  120  facilitates the process for connecting the first and second panel members  120 ,  140 . 
         [0030]      FIG. 8  discloses another alternative embodiment of configuration for connecting panel members. The first panel member  120  includes female configured flanges at the top and bottom plates. As shown in  FIG. 6 , the bottom plate of the first panel member  120  may include a female configured flange  124  that mates with a male configured flange  144  of the second panel member  140 . As shown in  FIG. 6 , the abutting connection between the top plates of the first and second panel members  120 ,  140  includes a tongue and groove arrangement. For example, the second panel member  140  may include a male configured flange that includes an upwardly projecting protrusion  147  that fits in a complementary groove or recess  127  located in the first panel member  120 . As shown in  FIG. 8 , the protrusion  143  is curved, preferably rounded. Other shaped projections may be used that facilitates the process for connecting the first and second panel members  120 ,  140 . 
         [0031]    The connected panel members disclosed in  FIGS. 4-8  are configured to resist lateral separation due to the provision of the tongue and groove type connection. Thus, the disclosed members reduce or eliminate the need for providing lateral clamping structures that were previously required to maintain the panel members in position during the FSW process. In  FIGS. 4-9 , the projection or male feature is shown to project downwardly or away from the top plate of one of the panel members. In an alternative embodiment, the projection or male feature may be configured to project upwardly into an open groove or recess facing downwardly from the top or bottom plate (see  FIG. 8 ) of the adjacent panel member. Thus, the overlapping flanges of the top plate may be configured as ether “male” or “female.” Also, as shown in  FIG. 8 , the projection is located away from the weld zone of the abutting structural members. Thus, the projection and groove would not be consumed by a welding process. Alternatively, the projection could be located at the end of one of the flanges that extends from each of the top and bottom plates. 
         [0032]    The panel members  120 ,  140  are preferably formed by extruding aluminum. Certain extruded aluminum sections may provide for a limited amount of flexibility to facilitate the connection of adjoining sections. However, for significant weight bearing applications (e.g., roads, bridges, rail cars, etc.) the required sectional modulus for the panel members is significant and, thus, the extruded panel members are generally not flexible. Thus, significant force may be required in order to connect the adjoining sections of panel members prior to welding. The shape of the projections disclosed in  FIGS. 4-8  functions to facilitate the connection. For example, the inclined ramp of the projection  142  shown in  FIG. 5  may slide over the female portion of the first panel member and into the groove  122 . Similarly, the curved portion of the projection  143  shown in  FIG. 7  will not catch or hang up on the corner of the female portion of the first panel member  120  thereby allowing the panel members  120 ,  140  to slide relative to one another and the projection member  143  to lodge into position in the groove  123 . 
         [0033]    In certain configurations, it may not be feasible to simply force or slide the adjacent panel members into a connected position prior to welding. As shown in  FIG. 8 , it may be necessary to configure the end of one of the panel members (the second panel member  140 , for example) to be in a position spaced apart from the adjacent panel member. The panel member  140 , for example, may hinge a location  145  on the top late so that when a force F is applied vertically downward on the top plate of the panel member, the top plate bends downward and the projection  143  is forced into the groove  123 . Alternatively, the overlying flange of one of the panel members may include a recess or groove that is forced downwardly to engage an upwardly extending projection in the adjacent panel member. 
         [0034]    The construction and arrangement of the structural members as shown in the preferred and other exemplary embodiments is illustrative only. Although only a few embodiments of the present structural assembly have been described in detail in this application, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g. variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in this application. Accordingly, all such modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present application.