CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present regular United States Patent Application claims the benefits of U.S. Provisional Application Ser. No. 60/729,369 filed on Oct. 21, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to fasteners and, more particularly, the invention pertains to weld nuts or weld studs that are secured in assemblies for engaging complementary fastener components in blind fastening situations.  
       BACKGROUND OF THE INVENTION  
       [0003]     It is known to use so-called “weld nuts” or “weld studs” as part of fastener systems in various assemblies. It is known to secure the weld nut, weld stud or other component in a fixed position for later engagement with the complementary component of the fastener system, when it is difficult to access the nut or other fastener component in the completed assembly. For example, it is known to use weld nuts in blind locations on automobile frames where components later secured to the frame are positioned in a laid on assembly where the nut is not visible but must anchor a component overlying the nut. 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. Again, by way of example, automobile frames are of such construction wherein frame members may be tubular to provide sufficient frame strength but each side of the tube is relatively thin and insufficient for threading to anchor a bolt to be secured thereto.  
         [0004]     In such installations, weld nuts have worked satisfactory, but are not without deficiencies. After the second component of the fastener system has been secured in the nut and the two parts of the assembly drawn together, the security of the weld holding the nut in place is often inconsequential as the two components are secured together. However, if it is desired to disassemble the assembly, since the nut often is not accessible, the security of the nut in its mounted location is important to allow the bolt to be loosened therefrom without the nut spinning together with the bolt. Further, when completing the assembly, it is necessary to tighten the bolt sufficiently and the nut must stay in fixed position to allow proper tightening without the nut spinning with the bolt.  
         [0005]     It is known to provide the surface of the weld nut or weld stud which is to bear against the sheet metal or supporting material with a plurality of raised integral projections or nibs. The weld nut or stud can be secured to the supporting material by resistance welding, which causes the projections to flow and alloy with the supporting material. If the weld is not secure, or if the fastening system is subjected to excessive torque or other forces, the weld zones can break loose, thus allowing the weld nut or stud to spin when the complementary fastener portion is connected thereto or disconnected therefrom.  
         [0006]     It can happen that the thread of the complementary fastener component or the thread on the weld nut or weld stud itself can be malformed or damaged during handling or installation. This then has the effect of increasing the torque required during installation or disassembly. Application of increased torque on the welded attachment can cause the weld to fail, freeing the weld nut or weld stud from the installed position. Since the weld nut or weld stud is used specifically because it will be inaccessible in the completed assembly, if the weld fails and the weld nut or weld stud is freed, significant difficulties can result.  
         [0007]     Accordingly, what is needed in the art is a fastener system utilizing a weld nut or weld stud which is more resistant to the application of high torque on the welded joint.  
       SUMMERY OF THE INVENTION  
       [0008]     The present invention provides a fastener system in which portions of a weld nut or weld stud are welded to the supporting structure and also are configured to physically interfere or engage with the mounting structure when torque is applied to the fastener system.  
         [0009]     In one aspect thereof, the present invention provides a weldable threaded fastener with a body having a first face and a second face, and a projection from the first face. The projection has a thread. A weld ring on the first side substantially encircles the projection.  
         [0010]     In another aspect thereof, the present invention provides a fastening system with a mounting structure having a keyhole therein including a hole and a slot extending from and communicating with the hole. The slot has a width defined between opposed slot sides. A threaded fastener includes a body having a first face and a second face, the body being sufficiently small to slide through the hole and being wider than the width of the slot. A projection from the first face has a thread. A weld ring on the first face substantially encircles the projection. The first face of the body is disposed adjacent a surface of the mounting structure along the slot. The projection extends into the slot. The weld ring is welded to the mounting structure where in contact with the surface of the mounting structure, and a portion of the weld ring projects into the slot.  
         [0011]     In still another aspect thereof, the present invention provides a method for attaching a threaded fastener to a mounting structure comprising steps of creating a keyhole in the mounting structure, including a hole and a slot extending from and communicating with the hole; and providing a threaded fastener including a body having a first face and a second face, a projection from the first side having a thread and a weld ring on the first face substantially encircling the projection. The method further includes inserting the body through the hole from a first surface of the mounting structure to a second surface of the mounting structure; positioning the projection in the slot and the first face of the fastener against the second surface of the mounting structure; welding the fastener to the second surface of the mounting structure while pulling the body toward the second surface; and locating a portion of the weld ring in the slot.  
         [0012]     An advantage of the present invention is providing a weld nut or weld stud that can be secured to relatively thin anchoring material, such as plate metals and the like, yet which is resistant to the application of high torque forces.  
         [0013]     Another advantage of the present invention is providing a fastener system in which a nut or stud is secured to mounting material by welding, and is provided with structure for physically interfering with the mounting material when torque forces are applied.  
         [0014]     Still another advantage of the present invention is providing a method for fastening a weld nut or weld stud which is efficient and uses standard welding apparatus and provides a more secure fastener system.  
         [0015]     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  
       [0016]      FIG. 1  is a cross-sectional view of a weld nut in accordance with the present invention;  
         [0017]      FIG. 2  is a cross-sectional view of a weld stud in accordance with the present invention;  
         [0018]      FIG. 3  is a perspective view of a weld nut of the present invention installed in a tubular mounting structure;  
         [0019]      FIG. 4  is a top view of another embodiment of the present invention;  
         [0020]      FIG. 5  is a top view of still another embodiment of the present invention;  
         [0021]      FIG. 6  is a top view of yet another embodiment of the present invention;  
         [0022]      FIG. 7  is a perspective view during an the installation process for a fastener of the present invention being installed in a tubular mounting structure;  
         [0023]      FIG. 8  is a perspective view similar to that of  FIG. 7  but illustrating a later time during the installation process; and  
         [0024]      FIG. 9  is a perspective view similar to  FIGS. 7 and 8 , but illustrating a still later time during the installation process. 
     
    
       [0025]     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  
       [0026]     Referring now more specifically to the drawings and to  FIG. 1  in particular, a weld nut  10  in accordance with the present invention is shown. Weld nut  10  is a body  12  having a threaded opening  14  therethrough. Threaded opening  14  is configured to engage a male threaded fastener, such as a bolt (not shown).  
         [0027]     Body  14  has first and second faces  16  and  18  on opposite sides of thereof. One of the faces  16 ,  18  is configured to confront a surface of a mounting structure  20 , such as a tubular mounting structure  20  as shown in  FIG. 3 . In the exemplary embodiment shown, surface  16  is configured to confront structure  20 .  
         [0028]     Surface  16  is provided with a substantially continuous weld ring  22  that surrounds threaded opening  14 . As known to those skilled in the art, weld ring  22  is material suitable for welding body  12  to mounting structure  20  when subjected to a welding process. In the exemplary embodiment shown, weld ring  22  has a substantially triangular cross-sectional shape, with a narrow distal peak or ridge  24  and a broader base at surface  16 .  
         [0029]     In the exemplary embodiment shown in  FIG. 1 , a boss  26  is provided as a projection from surface  16  within and substantially encircled by weld ring  22 . Threaded opening  14  extends also through boss  26 .  
         [0030]     Referring now to  FIG. 2 , a weld stud  30  in accordance with the present invention is shown. Weld stud  30  includes a body in the way of a head  32  and a shaft  34  with an external male thread  36  formed on the outer surface of shaft  34 . Head  32  defines first and second faces  38 ,  40  on opposite sides thereof, with first face  38  having shaft  34  extending as a projection therefrom. A substantially continuous weld ring  42  is provided on face  38 , substantially encircling shaft  34 . Weld ring  42  is of material suitable for welding head  32  to mounting structure  20  during a welding process. Weld ring  42  is similar in shape to weld ring  22 , having a broader base at surface  38  and narrower distal peak or ridge  44 , thus providing a substantially triangular cross-sectional shape for weld ring  42 .  
         [0031]     While exemplary embodiments of a weld nut  10  and of a weld stud  30  have been shown and described with respect to  FIGS. 1 and 2 , it should be understood that the embodiments shown herein are merely exemplary, and the present invention can be used for weld nuts and/or weld studs of different sizes and shapes. For example and not by way of limitation, in the exemplary embodiment of weld stud  30 , thread  36  is illustrated extending substantially the full length of shaft  34 . It should be understood that the present invention is not limited by the size, shape or manner of threading on shaft  34 , and the invention is expected to work well with shafts having threads thereon less than the full length thereof, shafts having pointed or tapered distal tips and the like. Further, the concepts of the present invention can be used also to secure structures that are more complex than just a simple nut or stud.  
         [0032]     Mounting structure  20 , which by example and not limitation is a side of a tubular mounting structure, is provided with a keyhole  50  extending therethrough, from a first or outside surface  52  to a second or inside surface  54 . Keyhole  50  has a major hole  56  and a narrower slot  58  communicating with hole  56  and extending away therefrom. Hole  56  is of sufficient size to allow body  12  of weld nut  10  or head  32  of weld stud  30  to pass therethrough from the outside thereof to the inside thereof. The width of slot  58 , defined between opposed slot sides  60 ,  62 , is sufficient to allow boss  26  or shaft  34  to slide there along, but is of insufficient width for body  12  or head  32  to be pulled therethrough from inside surface  54  to outside surface  52 . An end  64  of slot  58  is positioned to locate weld nut  10  or weld stud  30  in the proper axial position along the length of mounting structure  20  by the positioning of boss  26  or shaft  34  there against.  
         [0033]     Mounting structure  20  is illustrated having an open end visible in  FIG. 3 ; however, it should be understood that the present invention can be used in positions and on mounting structures having no access to a side there of, other than through keyhole  50 . With reference to the tubular mounting structure shown, weld nut  10  or weld stud  30  is inserted through hole  56  from the outside surface  52  to inside surface  54  such that boss  26  or shaft  34  can slide along slot  58 , with body  12  or head  32  otherwise substantially within tubular mounting structure  20 .  
         [0034]     Those skilled in the art will understand readily that for inserting and positioning weld nut  10  it may be advantageous to use a mandrel  70  having a male thread  72  engaged with threaded opening  14 . Those skilled in the art also will understand readily that it may be advantageous and convenient when inserting and positioning stud  30  to use a mandrel  74  ( FIGS. 7-9 ) having a female thread (not shown) engaged with thread  36 . Mandrels  70 ,  74  can be part of a welding machine used to secure weld nut  10  or weld stud  30  in mounting structure  20 . Again, those skilled in the art will readily understand that common well-known welding techniques can be used, such as resistance welding.  
         [0035]     Ridges  24  and  44  of weld rings  22  and  42 , respectively, enhance the efficiency and accuracy of welding in that the narrow distal ridges encourage arcing at the desired locations. Accordingly, during the welding process, weld rings  22 ,  42  are held against inside surface  54  of mounting structure  20 . Specifically, weld ring ridge or tip  24  or  44  is held against or near surface  54 . As welding continues, force is applied to draw weld nut body  12  or weld stud head  32  against inside surface  54 . A portion  78  of substantially continuous weld ring  22  or  42  is exposed in slot  58 . Without a confronting material to the exposed portion  78 , as body  12  or head  32  is drawn closer to inside surface  54  during welding, the exposed portion  78  of the weld ring is drawn into slot  58 . Even if the exposed portion  78  flows minimally during welding, a portion thereof remains disposed in slot  58 , between and adjacent slot sides  60 ,  62 . Accordingly, the exposed portion  78  interferes with slot sides  60 ,  62  and provides a physical obstruction or barrier to rotation of weld nut  10  or weld stud  30  relative to mounting structure  20 .  
         [0036]     It should be understood that boss  26  or an unthreaded portion of shaft  34 , for example, can be provided with geometric outer shapes to further resist rotation of weld nut  10  or weld stud  30  relative to mounting structure  20 . For example,  FIG. 4  illustrates a boss  80  having flat surfaces  82 ,  84  on opposite sides thereof, defining a width to fit relatively snuggly within slot  58 . It should be understood that while the previous embodiments shown can be positioned in any rotational position relative to slot  58 , the embodiment illustrated in  FIG. 4  requires proper alignment such that flat surfaces  82 ,  84  will slide along sides  60 ,  62  of slot  58 . To aid in alignment, more than two flat surfaces can be used. For example,  FIG. 5  illustrates a boss  90  having flat surfaces  92 ,  94 ,  96 ,  98   100  and  102  so that only minimal rotation is required to properly align opposed sides for sliding into slot  58 .  FIG. 6  illustrates yet another embodiment having a boss  110  with four flat surfaces  112 ,  114 ,  116  and  118 .  
         [0037]      FIGS. 7, 8  and  9  illustrate various situations during an installation process for weld stud  30 . Keyhole  50  is created in mounting structure  20 , extending between inside and outside surfaces  54 ,  52 . With mandrel  74  connected thereto, weld stud  30  is inserted in hole  56  of keyhole  50 . When head  32  has cleared inside surface  54 , shaft  34  is aligned with slot  58 , and mandrel  74  translates shaft  34  along slot  58  between slot sides  60 ,  62  to position shaft  34  where desired.  FIG. 8  illustrates shaft  34  at an intermediate position between hole  50  and slot end  64 . This can be an intermediate position ( FIG. 8 ), before shaft  34  is moved completely to slot end  64  ( FIG. 9 ). Alternatively, a fastener of the present invention, such as weld stud  30 , can be secured at an intermediate position along slot  58 . If secured in a position as shown in  FIG. 8 , two exposed portions  78  are established, providing still further resistance to relative rotation between weld stud  30  and mounting structure  20 .  FIG. 9  illustrates installation as welding occurs, with force applied on mandrel  74 , as illustrated by arrow  120 , to urge first face  38  toward inside surface  54  and locate exposed portion  78  in slot  58  as the remaining portions of weld ring  42  weld head  32  to mounting structure  20  on surface  54  adjacent slot  58 .  
         [0038]     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.  
         [0039]     Various features of the invention are set forth in the following claims.
A threaded fastener such as a weld nut or a weld stud has a projection from a surface thereof, with the projection bearing a thread. A weld ring substantially surrounds the threaded projection. In a fastener system using the fastener, a mounting structure has a keyhole including a larger diameter hole and a narrower diameter slot. In the assembly, a portion of the weld ring projects into the slot to resist rotation of the fastener relative to the mounting structure.