Abstract:
A fastener includes a t-nut having a barrel and a flange. The flange includes an opening which leads to a threaded barrel. The threaded barrel extends from the opening in the flange to a distal end portion thereof. An end cap has an annular recess on a first side thereof and has a raised annular ridge on a second side thereof. The raised annular ridge of the end cap is affixed to the flange of the t-nut by welding the end cap to the flange. Dirt, water and moisture cannot enter the barrel because the end cap is sealed to the flange. Additionally, the barrel may be relatively short as it is fully threaded prior to the affixation of the end cap to the flange.

Description:
This application claims priority to U.S. provisional patent application Ser. No. 61/089,859 filed Aug. 18, 2008. 
    
    
     FIELD OF THE INVENTION 
     The invention is the field of closed-end fasteners. 
     BACKGROUND OF THE INVENTION 
     Presently in the field there are several different ways that closed end fasteners are used and are manufactured. 
     Typical applications are molding applications where the closed end is used to prevent plastic from flowing into the back side of a fastener which would fill and render the threads on the fastener un-usable. Closed end fasteners are also used in tank (fluid container) type applications to prevent fluid from escaping the tank yet provide an external attachment point for the tank. Finally, closed end fasteners are commonly used in snow board applications where the closed end is used to prevent epoxy resins from flowing into the part and filling the threads with plastics. 
     Presently the market place use different types of closed end fasteners. Screw machine inserts are turned to shape and may be made out of brass and sometimes steel and aluminum. The most common shape of the insert is the hex shape shown in  FIGS. 1 and 1A . A drawback with brass inserts is high cost due to manufacturing time and material costs. 
       FIG. 1  is a view  100  of the prior art screw machine brass insert.  FIG. 1A  is another view  100 A of the prior art screw machine brass insert resting on one of the hexagonal sides. Hexagonal head  101  of the prior art screw machine brass insert includes a tapered recess  102  leading to the threads  103  of the prior art screw machine insert. Inner threads  103  of the prior art screw machine brass insert are illustrated in  FIGS. 1 and 1A . Threads  103  do not extend through the insert as illustrated in  FIG. 1A . Since the threads cannot extend through the insert a longer insert must be used to obtain the required thread depth. Larger hexagonal head  104  of the prior art screw machine brass insert is illustrated in  FIGS. 1 and 1A . Reference numeral  105  is the shank of the prior art screw machine brass insert. 
       FIG. 2  is a view  200  of the zinc die cast insert resting on flange  203 F.  FIG. 2A  is another view  200 A of the prior art zinc die cast insert shown resting on shank or barrel  201 . Zinc die cast inserts are molded to shape from a zinc alloy. Zinc die cast inserts are cost prohibitive due to the cost of the molds. Further, there is considerable difficulty in plating zinc and zinc alloys to provide good corrosion resistance and lack of strength of the zinc alloys. 
     Still referring to  FIGS. 2 and 2A , barbs or prongs  202  are illustrated protruding from shank  201 . Shank  201  terminates in end portion  205 . Flange  203 F tapers  203 T to edge  203 . Reference numeral  203 U denotes the underside of the flange. Inner threads  204  are illustrated in  FIG. 2 . 
     Cold headed steel parts are formed to shape then tapped. Issues with cold headed steel parts include the cost to manufacture and limitations on shapes that this manufacturing process can generate to fit different applications. 
     All three of these manufacturing methods have one other serious drawback. The amount of thread that can be tapped in a blind hole is limited. The hole cannot pierce through the back side of the part because it is closed and the tap must be stopped prior to bottoming out in the hole and breaking the tap in manufacturing. Due to these limitations, the length of the part must be increased to obtain the depth (amount) of thread desired. 
     SUMMARY OF THE INVENTION 
     A fastener includes a t-nut having a barrel and a flange. The flange includes an opening which leads to a threaded barrel. The threaded barrel extends from the opening in the flange to a distal end portion thereof. An end cap has an annular recess on a first side thereof and has a raised annular ridge on a second side thereof. The t-nut and the end cap may be made of steel or stainless steel. The raised annular ridge of the end cap is affixed to the flange of the t-nut by resistance welding the end cap to the flange. Dirt, water and moisture cannot enter the barrel because the end cap is sealed to the flange. Additionally, the barrel may be relatively short as it is fully threaded prior to the affixation of the end cap to the flange. 
     One example of the invention is a closed end t-nut with a sealing cap. The t-nut addresses the issues raised by current prior art manufacturing options. The method of manufacturing is to form a t-nut and then to tap its thread all the way through the part. Then in a separate operation, weld cap (end cap) is formed which has a circular (annular) raised weld ring. The end cap is then centered on the back of the flange of the t-nut and the raised weld ring is resistance welded to the flange of the t-nut. A seal is formed 360 degrees around the cap where it is welded to the flange of the t-nut thus preventing fluids from entering the part from the flange side of the t-nut. The resistance welding includes forcefully, under pressure, applying electrodes to the t-nut and the end cap bringing them into inter-engagement with each other and then passing electric current through the t-nut and end cap. The current is concentrated in the raised lip of the end cap heating and melting the raised ridge of the end cap and the flange together. 
     The advantages of this manufacturing method include a part fully threaded all the way to the cap. In other words, the thread is fully formed from near the flange end of the T-Nut to the end of the barrel. In this way, a short fastener is formed which functions as if it were a longer fastener. The manufacturing method for the short fastener of this invention is highly automated and per part cycle times are low. The fastener can be made from steel with a wide range of platings or even stainless steel for corrosion resistance. The fastener will be competitive from a manufactured cost standpoint. The fastener can be made in a wide variety of thread sizes, barrel lengths and flange diameters. The flange provides excellent pull out resistance in molding applications. 
     The round base part can be easily configured into a wide range of shapes. Final configurations for the sealed end T-nut include an upset hex form for plastic molding applications, a 4-prong configuration for snow boards, a propel nut for plastic applications, and a hopper feed configuration for automation into seating components where adhesive is sprayed onto the seat which holds the foam in place. 
     A process for making the fastener comprises the steps of: forming a t-nut having a barrel and a flange, said flange includes an opening, said barrel extending from said opening in said flange to a distal end portion; forming interior threads in said barrel; forming an end cap having an annular recess on a first side thereof and having a raised annular ridge on a second side thereof; and, resistance welding said raised annular ridge of said end cap to said flange of said t-nut. The t-nut may optionally be an upset hex t-nut, a four-prong t-nut, a propel nut, or a hopper feed t-nut. 
     A fastener, comprising, a t-nut having a barrel and a flange, said flange includes an opening, said barrel extending from said opening in said flange to a distal end portion; interior threads in said barrel; an end cap having an annular recess in a first side thereof and having a raised annular ridge on a second side thereof; and, said raised annular ridge of said end cap affixed to said flange of said t-nut is disclosed and claimed. The t-nut may be an upset hex t-nut, a four-prong t-nut, a propel nut, or a hopper feed t-nut. 
     It is an object of the present invention to provide a sealed end t-nut which includes threads which extend from the flange to the open end of the barrel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a screw machine brass insert. 
         FIG. 1A  is another view of the screw machine brass insert. 
         FIG. 2  is a zinc die cast insert. 
         FIG. 2A  is another view of the zinc die cast insert. 
         FIG. 3  is a top perspective view of a t-nut threaded completely through the part. 
         FIG. 3A  is a another perspective view of the t-nut threaded completely through the part. 
         FIG. 3B  is a top view of the t-nut with through threads. 
         FIG. 3C  is a side view of the t-nut with through threads. 
         FIG. 3D  is a cross-sectional view taken along the lines  3 D- 3 D of  FIG. 3C . 
         FIG. 4  is a perspective view of the outer portion of the end cap of the invention. 
         FIG. 4A  is a perspective view of the engaging portion of the end cap of the invention with a raised upper lip. 
         FIG. 4B  is a top view of the end cap. 
         FIG. 4C  is a side view of the end cap. 
         FIG. 4D  is a cross-sectional view taken along the lines  4 D- 4 D of  FIG. 4B . 
         FIG. 5  is an exploded perspective view taken of the end cap and t-nut with through threads. 
         FIG. 5A  is a perspective view of the end cap and the t-nut joined together. 
         FIG. 5B  is an end view of the end cap secured to the t-nut. 
         FIG. 5C  is a front view of the end cap secured to the t-nut. 
         FIG. 5D  is a cross-sectional view taken along the lines  5 D- 5 D of  FIG. 5C . 
         FIG. 6  is a perspective view of an upset hex t-nut and an end cap affixed thereto. 
         FIG. 6A  is a front view of an upset hex and end cap joined thereto. 
         FIG. 6B  is a cross-sectional view of the upset hex and end cap illustrated in  FIG. 6A  taken along the lines  6 B- 6 B. 
         FIG. 7  is a perspective view of a 4-prong t-nut and an end cap affixed thereto. 
         FIG. 7A  is a front view of a 4-prong t-nut and end cap joined thereto. 
         FIG. 7B  is a cross-sectional view of a 4-prong t-nut and an end cap illustrated in  FIG. 7A  taken along the lines  7 B- 7 B. 
         FIG. 8  is a perspective view of a propel nut and an end cap affixed thereto. 
         FIG. 8A  is a front view of a propel nut and end cap joined thereto. 
         FIG. 8B  is a cross-sectional view of a propel nut and an end cap illustrated in  FIG. 8A  taken along the lines  8 B- 8 B. 
         FIG. 9  is a perspective view of a hopper feed nut and an end cap affixed thereto. 
         FIG. 9A  is a front view of a hopper feed nut and end cap joined thereto. 
         FIG. 9B  is a cross-sectional view of a hopper feed nut and an end cap illustrated in  FIG. 9A  taken along the lines  9 B- 9 B. 
         FIG. 10  is a schematic of the steps of the process of making the sealed end t-nut. 
     
    
    
     DESCRIPTION OF THE INVENTION 
       FIG. 3  is a top perspective view  300  of a t-nut threaded completely through the part.  FIG. 3A  is another perspective view  300 A of the t-nut threaded  302  completely through the part.  FIG. 3B  is a top view  300 B of the t-nut with through threads. Flange  301  of the t-nut is viewed in both  FIGS. 3 and 3A  and is generally cylindrically shaped and terminates in a circumferential edge portion  306 . T-nuts are manufactured from sheets or slugs of steel (or stainless steel) which is deformed to include a barrel or shank such as that denoted by reference numeral  303 . Barrel or shank  303  terminates in an open end portion  308 . Shank  303  is cylindrically shaped and includes interior threads  302 . Interior threads  302  extend all the way from the opening  302 A in the flange to the end portion  308  of the shank  303 . Shank  303  transitions in a curved surface  304  into the underside  305  of the flange.  FIG. 3C  is a side view  300 C of the t-nut with through threads.  FIG. 3D  is a cross-sectional view  300 D taken along the lines  3 D- 3 D of  FIG. 3C . 
       FIG. 4  is a perspective view  400  of the outer portion of the end cap of the invention. The end cap may be made of steel or stainless steel. The end cap is generally disc shaped (cylindrically shaped) and terminates in a circumferential edge  420 . Outer lip  401  of the end cap is illustrated along with annular recess  402  and outer/center portion  403 .  FIG. 4A  is perspective view  400 A of the engaging portion (inner portion) of the end cap of the invention with a raised upper lip  411 . Recess  402  is formed in the outer portion of the end cap and creates a corresponding raised lip  411  in the inner portion of the end cap. The ridge can be created by stamping the end cap.  FIG. 4B  is a top view  400 B of the end cap (outer portion of the end cap) with the lip  401 , recess  402  and inner/center portion  412  illustrated.  FIG. 4C  is a side view  400 C of the end cap.  FIG. 4D  is a cross-sectional view  400 D taken along the lines  4 D- 4 D of  FIG. 4B . Sometimes herein the outer portion of the end cap denoted by the reference numerals  401 ,  402  and  403  is referred to herein as the first side of the end cap. Additionally, sometimes herein the inner portion of the end cap denoted by the reference numerals  410 ,  411  and  412  is referred to herein as the second side of the end cap. 
       FIG. 5  is an exploded perspective view  500  taken of the end cap and t-nut with interior threads therethrough. It will be noticed that the end cap (denoted generally by reference numerals  401 ,  402 ,  403 ) is aligned concentrically with flange  301  as indicated by the dashed line.  FIG. 5A  is a perspective view  500 A of the end cap (denoted generally by reference numerals  401 ,  402 ,  403 ) and the t-nut (denoted generally by reference numerals  301 ,  302 ,  303  and  308 ) joined together.  FIG. 5B  is an end view  500 B of the end cap secured to the t-nut.  FIG. 5C  is a front view of the end cap secured to the t-nut.  FIG. 5D  is a cross-sectional view  500 D taken along the lines  5 D- 5 D of  FIG. 5C  with a circumferential weld  501  joining end cap  401  to the t-nut. The weld is generated by resistance welding wherein a voltage is applied across the end cap and the t-nut. Raised lip  412  on the inner second portion of the end cap is illustrated in  FIG. 5  as being essentially flattened or melted to secure and seal the end cap to the t-nut. 
     Resistance projection welding produces coalescence of metals with the heat obtained from resistance to electrical current through the work parts which are held together under pressure by electrodes. The weld in projection welding is localized at predetermined points by projections. Localized heating is obtained by a projection on one or both of the parts being welded. The projection may be continuous in the form of an annular ring, namely, as the raised portion  411  as illustrated in  FIG. 4A . End cap annular projection  411  engages the t-nut under pressure caused by electrodes pushing the end cap and the t-nut together. Electric current is passed through and is focused where the projection engages the t-nut until the projection  411  melts and is fused to the t-nut in a concentric manner. See  FIG. 5D . 
       FIG. 10  indicates the steps  1000  for making the closed end fastener. The steps include forming a t-nut having a barrel and a flange  1001 ; tapping the barrel and threading the barrel  1002 ; forming an end cap having a recess in the outer side thereof and a raised ridge on the inner side thereof  1003 , forcefully interengaging the t-nut and the end cap with electrodes  1004 ; and, passing current through the t-nut and the end cap heating and melting the raised ridge of the end cap and the flange together  1005 . 
       FIG. 6  is a perspective view  600  of an upset hex t-nut and an end cap (denoted generally by reference numerals  401 ,  402  and  403 ) affixed thereto.  FIG. 6A  is a front view  600 A of an upset hex and end cap joined thereto.  FIG. 6B  is a cross-sectional view  600 B of the upset hex and end cap illustrated in  FIG. 6A  taken along the lines  6 B- 6 B. The weld  601  formed by resistance welding of the end cap to the upset hex nut flange  601 F is best illustrated in  FIG. 6  B and is also implicitly shown in  FIGS. 6 and 6A . By implicitly shown, it is meant that the flange and end cap are shown in engagement with no gap therebetween implying a connection therebetween. Flange  601 F terminates in edge portions  620 . Internally threaded barrel  602  is illustrated in  FIG. 6B  and shows that threads  602  extend completely therethrough. Slot  602  is illustrated separating the upset edge portions of the upset hex nut flange. Shank  603  of the upset hex nut is viewed in  FIGS. 6 ,  6 A and  6 B and terminates in end portion  603  of the upset hex nut. Upset edge portions  620  of the upset hex nut are deformed into leaf-like barbs or prongs. 
       FIG. 7  is a perspective view  700  of a 4-prong t-nut and an end cap (denoted generally by reference numerals  401 ,  402  and  403 ) affixed thereto. Each of the prongs is denoted by reference numeral  704 .  FIG. 7A  is a front view of a 4-prong t-nut and end cap joined thereto.  FIG. 7B  is a cross-section of a 4-prong t-nut and an end cap illustrated in  FIG. 7A  taken along the lines  7 B- 7 B. The weld  701  formed by resistance welding of the end cap to the upset hex nut flange  701 F is illustrated in  FIGS. 7 ,  7 A and  7 B. Internally threaded barrel  702  is illustrated in  FIG. 7B . Deformed prongs  704  are illustrated extending downwardly from flange  70  IF. Shank  703  of the 4-prong t-nut is viewed in  FIGS. 7 ,  7 A and  7 B and terminates in end portion  703  of the 4-prong t-nut. 
       FIG. 8  is a perspective view  800  of a propel nut and an end cap affixed thereto. The propel nut includes a shank or barrel  803  having barbs  802  interconnected with flange  801 F.  FIG. 8A  is a front view  800 A of a propel nut and end cap joined thereto.  FIG. 8B  is a cross-sectional view  800 B of a propel nut and an end cap illustrated in  FIG. 8A  taken along the lines  8 B- 8 B. The weld  801  formed by resistance welding of the end cap to the propel nut flange  801 F is illustrated in  FIG. 8B  and is also shown implicitly in  FIGS. 8 and 8A  wherein there is no gap between the end cap and the flange. By implicitly shown, it is meant that the flange and end cap are shown in engagement with no gap therebetween implying a connection therebetween.  FIGS. 8 ,  8 A and  8 B illustrate that the flange  801 F terminates in edge portions  806 . Internally threaded barrel  802  is illustrated in  FIG. 8B  and shows threads completely through the barrel. Internally threaded barrel  802  is illustrated in  FIG. 8B . Deformed prongs  804  are illustrated extending upwardly from the end portion  808 . Shank  803  of the propel nut is viewed in  FIGS. 8 ,  8 A and  8 B and terminates in end portion  808  of the propel nut. 
       FIG. 9  is a perspective view  900  of a hopper feed nut and an end cap affixed thereto.  FIG. 9A  is a front view  900 A of a hopper feed nut and end cap joined thereto.  FIG. 9B  is a cross-sectional view  900 B of a hopper feed nut and an end cap illustrated in  FIG. 9A  taken along the lines  9 B- 9 B. The weld  901  formed by resistance welding of the end cap to the hopper feed nut flange  901 F is illustrated in  FIG. 9B  and is also shown implicitly in  FIGS. 9 and 9A  wherein there is no gap between the end cap and the flange. By implicitly shown, it is meant that the flange and end cap are shown in engagement with no gap therebetween implying a connection therebetween.  FIGS. 9 ,  9 A and  9 B illustrate that the flange  901 F terminates in edge portions  906 . Internally threaded barrel  902  is illustrated in  FIG. 9B  and shows threads completely through the barrel. Internally threaded barrel  902  is illustrated in  FIG. 9B . Deformed prongs  907  are illustrated extending downwardly from flange  90  IF. Shank  903  of the hopper feed nut is viewed in  FIGS. 9 ,  9 A and  9 B and terminates in end portion  908  of the hopper feed nut. 
     REFERENCE NUMERALS 
     
         
           100 —prior art screw machine brass insert. 
           100 A—another view of the prior art screw machine brass insert 
           101 —hexagonal head of the prior art screw machine brass insert 
           102 —tapered recess leading to the threads of the prior art screw machine brass insert 
           103 —inner threads of the prior art screw machine brass insert 
           104 —larger hexagonal head of the prior art screw machine brass insert 
           105 —shank of the prior art screw machine brass insert 
           200 —prior art zinc die cast insert 
           200 A—another view of the prior art zinc die cast insert 
           201 —shank of the prior art zinc die cast insert 
           202 —barb or prong of the prior art zinc die cast insert 
           203 —end or edge of the head of the prior art zinc die cast insert 
           203 F—flange or face of the head of the prior art zinc die cast insert 
           203 T—tapered portion of the head of the prior art zinc die cast insert 
           203 U—underside of the flange 
           204 —inner threads of the prior art zinc die cast insert 
           205 —end of the shank of the prior art zinc die cast insert 
           300 —top perspective view of a t-nut thread all the way through the part 
           300 A—another perspective view of the t-nut with thread all the way through the part 
           300 B—top view of the t-nut with through threads. 
           300 C—side view of the t-nut with through threads. 
           300 D—cross-sectional view taken along the lines  3 D- 3 D of  FIG. 3C . 
           301 —flange of the head of the t-nut 
           302 —threads of the t-nut 
           303 —shank of the t-nut 
           304 —radius interconnecting the shank and flange 
           305 —flange 
           306 —circumferential edge of the flange 
           308 —end portion of the shank 
           400 —perspective view of the outer portion of the end cap of the invention 
           400 A—perspective view of the inner portion of the end cap of the invention with a raised upper lip 
           400 B—top view of the end cap 
           400 C—side view of the end cap 
           400 D—cross-sectional view taken along the lines  4 D- 4 D of  FIG. 4B   
           401 —lip of the end cap 
           402 —annular recess in outer portion of the cap 
           403 —outer/center portion of the cap 
           410 —inner lip of the end cap 
           411 —raised annular portion of the inside portion of the cap 
           412 —inner/center portion of the cap 
           420 —edge of the cap 
           500 —exploded perspective view taken of the end cap and t-nut with through threads 
           500 A—a perspective view of the end cap and the t-nut joined together 
           500 B—end view of the end cap secured to the t-nut 
           500 C—front view of the end cap 
           500 D—cross-sectional view taken along the lines  5 D- 5 D of  FIG. 5C   
           501 —resistance weld of the end cap and the t-nut 
           600 —perspective view of an upset hex t-nut and an end cap affixed thereto 
           600 A—front view of an upset hex nut and end cap joined thereto 
           600 B—cross-section of the upset hex nut and end cap illustrated in  FIG. 6A  taken along the lines  6 B- 6 B 
           601 —resistance weld of the end cap and the upset hex nut 
           601   f —flange 
           602 —threaded portion of the barrel 
           602 A—slot between the upset edge portions of the upset hex nut 
           603 —shank of the upset hex nut 
           608 —end portion of the upset hex nut 
           620 —upset edge portion of the upset hex nut 
           700 —perspective view of a 4-prong t-nut and an end cap affixed thereto 
           700 A—front view of a 4-prong t-nut and end cap joined thereto 
           700 B—cross-sectional view of a 4-prong t-nut and an end cap illustrated in  FIG. 7A  taken along the lines  7 B- 7 B 
           701 —resistance weld of the end cap and the 4-prong t-nut 
           701 F—flange portion of the 4-prong t-nut 
           702 —threaded barrel 
           702 A—cut portion of the 4-prong t-nut 
           703 —shank of the 4-prong t-nut 
           704 —deformed flap of the 4-prong t-nut 
           708 —end of shank portion 
           800 —perspective view of a propel nut and an end cap affixed thereto 
           800 A—front view of a propel nut and end cap joined thereto 
           800 B—cross-sectional view of a propel nut and an end cap illustrated in  FIG. 8A  taken along the lines  8 B- 8 B 
           801 —resistance weld of the end cap and the propel nut 
           801 F—flange portion of the propel nut 
           802 —threaded barrel 
           802 A—barb on shank of the propel nut 
           803 —shank of the propel nut 
           806 —edge of the flange of the propel nut 
           900 —perspective view of a hopper feed nut and an end cap affixed thereto 
           900 A—front view of a hopper feed nut and end cap joined thereto 
           900 B—cross-section of a hopper feed nut and an end cap illustrated in  FIG. 9A  taken along the lines  9 B- 9 B 
           901 —resistance weld of the end cap and the hopper feed nut 
           901 F—flange portion of the hopper feed nut 
           906 —edge of the flange of the hopper feed nut 
           907 —prongs of the hopper feed nut 
           908 —end of barrel 
           1000 —schematic diagram for making the closed end fastener 
           1001 —forming a t-nut having a barrel and a flange 
           1002 —tapping the barrel and threading the barrel 
           1003 —forming an end cap having a recess in the outer side thereof and a raised ridge on the inner side thereof 
           1004 —forcefully interengaging the t-nut and the end cap with electrodes 
           1005 —passing current through the t-nut and the end cap heating and melting the raised ridge of the end cap and the flange together 
       
    
     The invention has been set forth by way of example only. Those skilled in the art will readily recognize that changes may be made to the invention without departing from the spirit and scope of the appended claims.