Abstract:
A weld nut includes a separate nut and a separate weld plate engaged one with the other to constrain relative axial movement of one with respect to the other. Confronting surfaces along an interface of the nut and weld plate are configured to interfere one with the other and constrain relative rotational movement between the nut and weld plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present regular United States Patent Application claims the benefits of U.S. Provisional Application Ser. No. 60/781,056 filed on Mar. 10, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to fasteners and, more particularly, the invention pertains to fasteners such as weld nuts that are secured in assemblies for subsequent engagement by a complementary fastener component such as a bolt or stud. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is known to use so-called weld nuts as part of fastener systems in a variety of installations and assemblies. It is known to secure the weld nut in a fixed position for later engagement with the complementary component of the fastener system, particularly when it is difficult to access the location at which the nut is to be installed for completing the assembly. For example, it is known to use weld nuts in various locations on automobiles where components later secured thereto are positioned in a laid on assembly that covers the nut before the fastener is secured. Weld nuts are used also in installations in which the anchoring component is of insufficient thickness to be threaded for anchoring a fastener, such as a bolt, directly. Weld nuts are used also to improve speed and efficiency in later assembly, even when the nut is accessible in the subsequent assembly. For example, it is known to provide a two-piece weld nut in which a weld plate is provided with a round hole and a nut includes a collar or hub secured in the hole. The nut and weld plate are rotatable relative to one another. 
         [0004]    Weld nuts have worked satisfactorily for these and other installations, but are not without deficiencies. For example, in blind installations wherein the nut is not accessible as the assembly is being completed, it is necessary for the nut to be secured and not rotatable relative to the weld plate. The aforedescribed two piece weld nut assembly in which the nut and plate are rotatable relative to each other is not suitable for such installations. For these installations, other types of weld nuts have been used. For example, a weld nut can be made from a single, monolithic piece of material including the threaded fastener component and a plate-like component by which the weld nut is anchored in the assembly. However, techniques used for shaping a nut and a weld plate from a single piece of material have been expensive and wasteful of material. Other structures also have been used, including two piece weld nut assemblies in which one or more nut is welded to a weld plate which is subsequently welded in the assembly. Again, manufacturing techniques for weld nuts of this type can be time consuming and expensive. 
         [0005]    It is known also to provide a plurality of projections or weld nibs on the surface of the weld nut which is to confront the anchoring or supporting material. The weld nut is then secured to the supporting material by resistance welding, which causes the projections to flow and alloy with the supporting material. It can be difficult to see if acceptable alloying has occurred in that the weld nibs are beneath the plate. Also, flash from the welding process can contact threaded portions of the weld nut, causing thread damage and difficult subsequent engagement with a bolt or other threaded component attached thereto. If the welds are not secure, or if the fastening system is subjected to excessive torque or other forces, the weld zones can break loose, allowing the weld nut to spin when the complementary fastener portion is connected thereto or disconnected therefrom. Excessive force conditions as described can occur particularly if weld flash during the attachment of the weld nut has come in contact with the threads of the weld nut, thereby increasing torque requirements to thread the bolt into the weld nut. Excessive force conditions also can occur if the thread on the weld nut is malformed or damaged during handling and installation. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a two piece weld nut in which simple stamping processes are used to engage the nut and weld plate to restrain relative axial movement therebetween, and wherein an interface between the nut and weld plate is configured to prevent relative rotation between the weld nut and weld plate. 
         [0007]    In one aspect thereof, the present invention provides a fastener assembly with a plate defining a hole and a fastener having a hub disposed in the hole. The hub is secured in the hole, and the plate and the fastener are substantially immovable axially one relative to the other. The plate and the fastener have confronting surfaces establishing an interface between the plate and the fastener, the confronting surfaces including complementary configurations interfering one with the other in either direction of relative rotation between the plate and the fastener with the hub in the hole. 
         [0008]    In another aspect thereof, the present invention provides a weld nut with a nut having a body with a threaded bore and a hub extending axially from the body. The hub is narrower than the body and the body has an end surface radially outward of the hub. A first set of contours is provided on the end surface of the body. A plate has a hole and a nut facing surface. A second set of contours is provided on the nut facing surface of the plate. The hub is secured in the opening, and the nut and the plate are substantially immovable axially one relative to the other. The first and second contours internest one with the other, the contours abutting one against the other to limit relative rotational movement between the nut and the plate. 
         [0009]    In a still further aspect thereof, the present invention provides a fastener assembly with a threaded body having an end surface and a hub extending axially from the end surface of the body. The end surface outwardly of the hub defines alternating ridges and valleys. A plate has a hole, and the hub is disposed in the hole and secured to the plate in a manner to constrain relative axial movement between the body and the plate. A surface of the plate defines a second set of alternating valleys and ridges internested with the ridges and the valleys of the end surface. 
         [0010]    An advantage of the present invention in one form thereof is providing a weld nut that can be manufactured in a cost efficient manner. 
         [0011]    Another advantage of a form of the present invention is providing a weld nut having weld nibs remotely located relative to the threads of the weld nut, to reduce potential for thread damage resulting from weld flash contacting the threads when the weld nut is installed in an assembly. 
         [0012]    A further advantage of a form of the invention is providing a weld nut as a two piece assembly so that the nut and weld plate portions thereof can be provided of different materials. 
         [0013]    A still further advantage of a form of the present invention is providing a weld nut in which the nut and weld plate thereof are rotationally secured, one with respect to the other so that relative rotation between the nut and weld plate portions are inhibited. 
         [0014]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of a two piece weld nut in accordance with the present invention; 
           [0016]      FIG. 2  is a perspective view of another form of a weld nut of the present invention, illustrating a bottom of the weld nut; 
           [0017]      FIG. 3  is a perspective view of the nut portion for the weld nuts shown in the preceding drawings; 
           [0018]      FIG. 4  is a cross-sectional view of the weld nut shown in  FIG. 2 ; 
           [0019]      FIG. 5  is a perspective view similar to that of  FIG. 1 , but illustrating another modified form of the present invention; 
           [0020]      FIG. 6  is an exploded view of another embodiment of the present invention; 
           [0021]      FIG. 7  is an exploded view of yet another embodiment for a two piece weld nut of the present invention; 
           [0022]      FIG. 8  is an exploded view of a further embodiment for a two piece weld nut of the present invention; and 
           [0023]      FIG. 9  is an exploded view of still another embodiment for a two piece weld nut of the present invention. 
       
    
    
       [0024]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use herein of “including”, “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof, as well as additional items and equivalents thereof. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    Referring now more specifically to the drawings, and to  FIG. 1  in particular a fastener assembly in the form of a weld nut  10  in accordance with the present invention is shown. Weld nut  10  is a two piece assembly including a fastener such as a nut  12  and a weld plate  14 . Weld nut  10  can be made of a variety of materials including metals and the like. An advantage of certain forms of the present invention is that nut  12  and weld plate  14  can be provided from different materials. Accordingly, nut  12  can be made of material advantageous for the fastening function, such as brass or other costly material, and weld plate  14  can be made of a lesser expensive material, such as steel, more suited for welding attachment within the assembly. 
         [0026]    Nut  12  includes a main body  16  having an axial opening therethrough defining a thread  18  for engagement with a complementary threaded stud, bolt or the like (not shown). A hub  20 , best seen in  FIG. 3 , extends axially away from one end surface  22  of body  16 . Hub  20  is narrower than body  16  such that end surface  22  extends radially outwardly relative to hub  20 . In the illustrated embodiment shown in  FIGS. 1-5 , hub  20  has a round periphery and has a tapered inner surface  24  whereby a distal end edge  26  of hub  20  is thinner than portions of hub  20  closer to body  16 . 
         [0027]    End surface  22  is provided with a first set of contours including alternating ridges  28  and valleys  30 . In the illustrated embodiment, ridges  28  and valleys  30  extend substantially radially outwardly along end surface  22 . Ridges  28  and valleys  30  are substantially square cut, such that the bottoms of valleys  30  are flat and the tops of ridges  28  are flat, with substantially flat sides  32  that are substantially perpendicular to the flat upper surface of an adjacent ridge  28  and the flat bottom surface of an adjacent valley  30 . 
         [0028]    Weld plate  14  in the exemplary embodiment is a substantially flat, washer-like body, although other shapes and configurations can be used also.  FIG. 1  illustrates a round weld plate  14  having a nut facing surface  40 . Weld plate  14  defines a hole  42  configured for receiving hub  20  therein. As illustrated in  FIG. 4 , hole  42  can include a tapered surface  44  expanding outwardly away from surface  40 . Hole  42  also can define an undercut  46  and a diametrically larger opening at a surface opposite nut facing surface  40 . 
         [0029]    Nut facing surface  40  defines a second set of contours including valleys  48  and ridges  50  shaped and arranged to complement ridges  28  and valleys  30  whereby each are received one within the other in a nested arrangement. Accordingly, ridges  28  are received in valleys  48  and ridges  50  are received in valleys  30 . Accordingly, valleys  48  and ridges  50  extend radially outwardly from hole  42  over nut facing surface  40 . Depending on the overall size of weld plate  14 , valleys  48  and ridges  50  need not extend completely to the outer edge of weld plate  14  so long as each are of sufficient length for complete nesting with ridges  28  and valleys  30  of nut  12 . Valleys  48  and ridges  50  are square cut similarly to that described previously for ridges  28  and valleys  30 . Accordingly, nut facing surface  40  is provided with substantially flat bottoms for valleys  48  and substantially flat tops for ridges  50 , with substantially flat sides  52  perpendicular to the adjacent valleys  48  and ridges  50 . 
         [0030]    In an assembled weld nut  10 , hub  20  is inserted into hole  42  and ridges  28  and valleys  30  of end surface  42  are nested into valleys  48  and ridges  50  of nut facing surface  40 . Hub  20  is expanded, crushed, deformed or otherwise manipulated to secure hub  20  in hole  42 , whereby relative axial movement between nut  12  and weld plate  14  is constrained. Manipulation of hub  20  to secure it in hole  42  can be performed by pressing, as those skilled in the art will readily understand. The thinner wall along surface  24  toward distal end edge  26  can facilitate outward expansion of hub  20 . Portions of end edge  26  can be expanded into undercut  46 , to secure relative axial positioning of nut  12  and weld plate  14 . 
         [0031]    Nut  12  and weld plate  14  are held tightly one against the other such that the interface of end surface  22  and nut facing surface  40  includes the nesting of ridges  28  in valleys  48  and ridges  50  in valleys  30 . Relative rotation between nut  12  and weld plate  14  is thereby restricted in both directions. The substantially square cut configurations of ridges  28 , valleys  30 , ridges  48  and valleys  50  establish torque resistance to relative rotation between nut  12  and weld plate  14 . 
         [0032]    Whereas weld plate  14  in the embodiments illustrated in FIGS. I and  5  is substantially round, it should be understood that other configurations also can be used. For example, the embodiment of  FIG. 2  includes a weld plate  60  having a hex shaped perimeter. 
         [0033]    Weld nibs  62  are provided for securing weld nuts of the present invention on the supporting body (not shown).  FIG. 1  illustrates an embodiment having three weld nibs  62 .  FIG. 2  and  FIG. 5  illustrate embodiments having more weld nibs  62 . The number, location and spacing for weld nibs  62  can be selected for advantageous installation and attachment on the supporting structure. Weld nibs  62  are provided at the outer edge of the weld plate. Accordingly, flash that may occur during the installation process is more distantly located from thread  18 , thereby reducing the risk for damage to thread  18  from contact with the weld flash. Further, with the bonding or alloying performed at more distant locations from the center axis of the weld nut assembly, greater torque resistance is provided to reduce the risk of the weld nut being dislodged from its installed position. Further, in some situations, weld nibs  62  at the perimeter of the weld plate can allow for visual inspection of the weld integrity during installation. 
         [0034]    In the embodiments thus far described, the interface between nut  12  and weld plate  14  or  60  is established along a substantially radial plane relative to the axis of the weld nut. Accordingly, hub  20  of nut  12  and hole  42  of the weld plate can be round, and. Thus, precise rotational orientation of the nut with respect to the weld plate during assembly is not required. With relatively narrow ridges and valleys, as pressing is performed to secure nut  12  in weld plate  14  or  60 , the ridges and valleys are drawn into the required nesting relationship. 
         [0035]    It should be understood that other configurations for an interfering relationship between the interface of a nut and weld plate also can be used. For example, an outer surface of the hub and the hole in the weld plate can be complementarily shaped to restrict relative rotation between the nut and weld plate.  FIG. 6  illustrates a weld nut  70  including a nut  72  and a weld plate  74 . Nut  72  includes a hex-shaped hub  76 , and weld plate  74  defines a complementary hex-shaped hole  78 . 
         [0036]    In  FIG. 7 , a weld nut  80  includes a nut  82  and a weld plate  84 . A hub  86  of nut  82  includes a spline-like configuration of alternating ridges and valleys, and weld plate  84  defines a complementarily notched opening  88  for engaging the spline configuration of hub  86 . 
         [0037]      FIG. 8  illustrates a weld nut  90  including a nut  92  and a weld plate  94 . A hub  96  is shaped similarly to a gear, and a hole  98  of weld plate  94  is complimentarily shaped for receiving hub  96 . 
         [0038]      FIG. 9  illustrates a still further embodiment of the present invention in which a nut plate  100  includes a nut  102  and a weld plate  104 . A hub  106  of nut  102  is oval in shape, and weld plate  104  defines an oval hole  108  for receiving hub  106 . 
         [0039]    The attachment of nuts  72 ,  82 ,  92  and  102  in weld plates  74 ,  84 ,  94  and  104 , respectively, can be performed by manipulation of the hubs as described previously. However, it should also be understood that any of the various hubs described herein, as well as other variations thereof, also can be secured in an appropriate weld plate opening by a press-fit or interference fit of the hub in the opening, without substantial alteration of the hub. 
         [0040]    Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art. 
         [0041]    Various features of the invention are set forth in the following claims.