Abstract:
A method for fastening two substantially coplanar edges without a weld. The method includes: configuring a dovetail feature on a first edge; configuring a complementary dovetail feature receptacle on a second edge to receive the dovetail feature therein; disposing the dovetail feature within the complementary dovetail receptacle; and swaging an interface defined between the dovetail feature in said first edge and said complementary dovetail feature in the second edge to swage mating edges defining the dovetail feature and the dovetail receptacle at at least six swage contact points.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a continuation application of U.S. application Ser. No. 10/853,425 filed Oct. 18, 2004, now U.S. Pat. No. 7,404,252 to which U.S. application Ser. No. 11/834,918, filed Apr. 15, 2008, now U.S. Pat. No. 7,357,682 claims the benefit of priority, the disclosure of which is incorporated by reference herein in its entirety. 

   FIELD OF THE INVENTION 
   The present invention relates generally to a method and apparatus for fastening two coplanar edges without a weld and more specifically to a method and apparatus for fastening a docking cassette for printed circuit boards that eliminates use of a spot or fillet weld and a resulting burn mark thus eliminating touch-up to coat the welded area. 
   BACKGROUND OF THE INVENTION 
   As integrated circuit (IC) and printed circuit board (PCB) design and fabrication techniques become more sophisticated, computer system design techniques must also become more sophisticated. This is because as IC&#39;s and PCB&#39;s become more densely populated, their performance capabilities and speeds increase and computer systems which employ these IC&#39;s and PCB&#39;s must be able to support the increase in performance. In addition, as businesses that employ these computer systems and components become more sophisticated, they demand greater performance from their computer systems resulting in increasingly densely populated PCB&#39;s and computer systems having tightly packed packages. As a result of these tightly packed packages, these PCB&#39;s and computer systems are susceptible to a variety of problems which must be considered. 
   In order to increase decorative appearance of packaging while providing denser packages, it has become necessary to eliminate a weld pad area such as spot and fillet welds. Elimination of a weld pad area allows the use of pre-plated materials in areas where customers have a clear view without burn marks typically associated with a weld pad area. Furthermore, by eliminating burn marks, an additional costly touch-up process to coat the welded area is eliminated 
   For example, it is known to join complimentary configured dovetailed edges using a “cross” patterned swage across an interface thereof to join mating dovetail edges without a spot or fillet weld. The “cross” patterned swage forms three edge swaging contact points. However, this process appears to work only for light loads and small applications. 
   Accordingly, a method and apparatus for fastening two coplanar edges without using welding and touch-up processes that creates a stronger bond for use with heavier loads and/or larger applications is desired. 
   SUMMARY OF THE INVENTION 
   A method and apparatus for fastening two substantially coplanar edges without a weld is disclosed. The method and apparatus include configuring a dovetail feature on a first edge and configuring a complementary dovetail feature receptacle on a second edge to receive the dovetail feature therein. The dovetail feature is disposed within the complementary dovetail receptacle and an interface defined between the dovetail feature in said first edge and said complementary dovetail feature in the second edge is swaged to swage mating edges defining the dovetail feature and the dovetail receptacle at least six swage contact points. In one embodiment the swaging is with a hollow circle punch. 
   In another embodiment, a docking apparatus includes a cassette housing defining a housing cavity for one of a printed circuit board and allowing air flow therethrough; a dovetail feature configured on a first edge defining the cassette housing; a complementary dovetail feature receptacle configured on a second edge defining the cassette housing to receive the dovetail feature therein, the dovetail feature being disposed within the complementary dovetail receptacle; and a swaged interface defined between the dovetail feature in the first edge and the complementary dovetail receptacle in the second edge, the swaged interface mating edges defining the dovetail feature and the dovetail receptacle at least six swage contact points. In an exemplary embodiment the swaging is with a hollow circle punch. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the figures, which are exemplary embodiments, and wherein the like elements are numbered alike: 
       FIG. 1  is an exploded overall view of a docking cassette and a computer system in accordance with an embodiment of the invention. 
       FIG. 2  is a perspective view of a docking cassette in accordance with an embodiment of the invention; 
       FIG. 3  is an exploded view of a docking cassette in accordance with an embodiment of the invention; 
       FIG. 4  is a perspective view of a housing bezel disposed on the docking cassette of  FIG. 3  illustrating mating dovetails with a circle swage providing six contact points therebetween in accordance with an exemplary embodiment; 
       FIG. 5  is a perspective view of an alternative exemplary embodiment of an air flow filler book in place of the docking cassette of  FIG. 2  illustrating mating dovetails with a circle swage providing six contact points therebetween in accordance with an exemplary embodiment; 
       FIG. 6  is an enlarged side view of  FIG. 5  illustrating the mating dovetails having the circle swage providing the six contact points therebetween in accordance with an exemplary embodiment; 
       FIG. 7  is a partial view of the mating dovetails of  FIG. 5  swaged with a conventional cross pattern punch profile illustrating three swage contact points across an interface of the mating dovetails; 
       FIG. 8  is a partial view of the mating dovetails of  FIG. 5  swaged with a circle punch profile illustrating six swage contact points across the interface of the mating dovetails; 
       FIG. 9  is a partial view of an alternative embodiment of mating dovetails of  FIG. 8  being ovalized and swaged with a circle punch profile illustrating six swage contact points across the interface of the mating dovetails; 
       FIG. 10  is a partial view of another alternative embodiment of mating dovetails of  FIGS. 8 and 9  having four sides and swaged with a circle punch profile illustrating six swage contact points across the interface of the mating dovetails. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring generally to the  FIG. 1 , a docking apparatus or cassette  10  for mounting a printed circuit card (PCC) into a computer system  12  is shown, in accordance with an embodiment of the invention. Docking apparatus  10  preferably provides structural support to the PCC so as to allow for the easy insertion and removal of the PCC from computer system  12 , as well as thermal and electrical isolation from other PCC&#39;s and components within the computer system. 
   Docking cassette  10  is disposed onto a computer system main board  14  or main printed circuit board (PCB) having a PCB connector receptacle  16 , a first receptacle  18  and a second receptacle  20 . Docking cassette  10  is preferably disposed onto computer system main board  14  such that a PCB connector is adjacent to PCB connector receptacle  16 . In addition, main board  14  is slidably engaged with a cable tray  22  for releasably supporting and securing computer system  12  in a system rack (not shown) 
   Referring to  FIGS. 2 and 3 , docking apparatus  10  for mounting to a printed circuit board (PCB) in computer system  12  is shown, in accordance with an embodiment of the invention. Docking apparatus  10  preferably includes a cassette housing  24 , a linkage mechanism  26  and a housing bezel  30 . Cassette housing  24  preferably includes a housing base  32 , a housing cover  34  and a housing wall  36 , wherein housing base  32  and housing wall  36  are non-movably associated with each other and disposed relative to each other so as to define a housing cavity  38  for movably containing a PCC  40 . 
   In accordance with an exemplary embodiment, housing base  32  preferably includes a linkage cavity  42  and four mounting devices  44  for movably holding PCC  40 . PCC  40  preferably includes a PCC mounting mechanism  46  and mounting device  44  preferably includes a device opening  48  for slidingly containing PCC mounting mechanism  46 , wherein PCC mounting mechanism  46  may be a screw, a pin or any mounting mechanism suitable to the desired end purpose. In addition, housing base  32  preferably includes a linkage mounting receptacle  50  for associating linkage mechanism  26  with housing base  32 . In accordance with an exemplary embodiment, although linkage mounting receptacle  50  is preferably a receptacle opening for receiving a linkage mounting screw  52 , linkage mounting receptacle  50  may be any receptacle device suitable to the desired end purpose, such as a clip receptacle. In accordance with an exemplary embodiment, it is considered within the scope of the disclosure that PCC  40  may be movably associated with housing base  32  using any device or method suitable to the desired end purpose, such as a screw or pin. 
   Housing wall  36  preferably includes a cable opening  54 , a PCB connector opening  56  and a plurality of vent openings  58 . In addition, housing wall  36  preferably includes a first protrusion  60  and a second protrusion  62 , wherein first protrusion  60  and second protrusion  62  are disposed so as to lockingly engage with main board  14  of computer system  12 . In accordance with an embodiment of the invention, first protrusion  60  and second protrusion  62  are shown as being disposed on housing wall  36 . However, it is considered within the scope of the invention that first protrusion  60  and second protrusion  62  may be disposed anywhere on cassette housing  24  in a manner suitable to the desired end purpose. Moreover, housing wall  36  preferably includes at least one mounting structure  64  which defines a threaded cavity  66  for receiving a mounting apparatus  68 , such as a screw. In addition, PCB connector opening  56  and cable opening  54  are preferably disposed so as to allow communication with the PCB connector  70  and the PCC cable connections  72  when PCC  40  is disposed within housing cavity  38 . 
   Housing cover  34  preferably includes at least one cover opening  74  disposed so as to allow communication with mounting structure  64  when housing cover  34  is associated with housing wall  36 . Cover opening  74  is preferably disposed so as to allow mounting apparatus  68  to communicate with threaded cavity  66  for removably securing housing cover  34  with housing wall  36 . Although an exemplary embodiment describes housing cover  34  being removably secured with housing wall  36 , it is considered within the scope of the disclosure that housing cover  34  may also be removably secured with housing base  32  and/or housing wall  36  using any mounting device or method suitable to the desired end purpose. 
   Referring now to  FIG. 3 , housing bezel  30  preferably includes an inner tail-stock bezel  76 , an EMC gasket  80  and an outer tail-stock bezel  82 . Inner bezel  76  preferably includes a forward bezel wall  84  having at least one forward opening  86 . EMC gasket  80  preferably includes a plurality of apertures  88  disposed along a length defining gasket  80  and plurality of retaining clips  90  extending from an edge of gasket  80  for attachment to a flange extending from inner bezel  76  described more fully below having apertures aligned with apertures  88  of gasket  80  for venting air therethrough. Outer tail-stock bezel  82  preferably includes a tail-stock front  92  having a tail-stock front opening  94  and a tail-stock wall  96  having a tail-stock top  98 , a tail-stock bottom  100  and a tail-stock side  102 . In accordance with an embodiment of the invention, tail-stock front  92  and tail-stock wall  96  are preferably non-movably associated with each other so as to form a tail-stock cavity  104 , discussed more fully herein below in accordance with an exemplary embodiment. In addition, tail-stock bottom  100  preferably includes at least one flanged opening  106 . Tail-stock top  98  also preferably includes at least one tail-stock mounting hole  108  for mounting housing bezel  30  to cassette housing  24 . 
   Still referring now to  FIG. 3 , inner tail-stock bezel  76  includes a flange  110  extending from forward bezel wall  84 . Flange  110  includes apertures  112  disposed in a length thereof for allowing air to pass therethrough. Retaining clips  88  extending from an edge defining a surface of EMC gasket  80  are configured to clip onto flange  110  such that apertures  90  of gasket  80  are aligned with apertures  112  disposed along flange  110 . Inner bezel  76  further includes a mounting lip  114  extending from an opposite edge of wall  84  in the same direction and substantially parallel to flange  110 . Mounting lip  114  is configured to mount PCC  40  in an offset position within docking apparatus  10  so that a bottom surface of PCC  40  is not positioned against housing base  32 . 
   Referring now to  FIGS. 3 and 4 , inner bezel  76  having EMC gasket  80  coupled thereto is disposed within tail-stock cavity  104  such that apertures  90  of gasket  80  and apertures  112  of inner bezel are aligned with vents  120  configured in tail-stock wall  96  of outer tail sock bezel  82 . In a preferred embodiment, apertures  90  and  112  align with two rows of vents  120  for allowing air to flow therethrough. The two rows of vents  120  is best seen in  FIG. 4 . 
   Referring now to  FIG. 4  and in accordance with an exemplary embodiment of the disclosure, tail-stock walls  96  and  102  are non-movably associated with each other so as to form a tail-stock cavity  104  by engaging corresponding dovetail features  130  to form a swage interface therebetween. More specifically, after joining respective dovetail features defining edges of mating tail-stock walls  96 ,  102 , a hollow circle punch (not shown) is used to swage the interface therebetween imprinting a circle  132  thereover and provide six swage contact points  136  therebetween as best seen with reference to  FIG. 6 . 
   Referring now to  FIG. 5 , an alternative exemplary embodiment of forming a weldless connection between dovetail features is illustrated with respect to an air flow filler book assembly  200 . Air flow filler book assembly  200  is used in place of docking cassette  10  to fill a card slot space in computer system  12  while allowing air flow through vents  220  configured in a tail stock front  192  and opposing tail stock walls  196  of assembly  200 . 
   Referring now to  FIG. 6 , an enlarged side view of assembly  200  of  FIG. 5  is illustrated showing six swaging contact points  136  across dovetail features  130  as a result of punching circle  132  thereover. Complementary configured dovetail features  130  include a pair of dovetails  232  each configured in an outboard end of a flange  230  extending from opposite walls  196  and each bent substantially normal thereto towards each other and coplanar with a side wall  202 . Side wall  202  includes a pair of opposing complementary dovetail receptacles  234  configured to receive a corresponding dovetail  232  therein. A hollow circle punch (not shown) is aligned over the mating dovetail features  130  provided by interfacing dovetails  232  and respective receptacles  234  and is provided a force to swage an interface therebetween. Six swage contact points  136  result from the swage corresponding to a profile of the hollow circle punch intersecting an interface between dovetails  232  and corresponding receptacles  234 . 
   Referring now to  FIGS. 7 and 8 , a comparison between a “cross pattern” punch profile vs. a circle punch profile is illustrated.  FIG. 7  illustrates a “cross patterned” punch profile generally at  300  across interlocking coplanar dovetail features  130  including a three sided dovetail  332  and a complementary configured three sided receptacle  334 . The cross pattern punch profile  300  provides three swage contact points  340 .  FIG. 8  illustrates a “circle” punch profile  350  generally across interlocking coplanar dovetail features  130  including three sided dovetail  332  and complementary configured three sided receptacle  334 . The circle punch profile  350  provides twice as many swage contact points  340  (i.e., six) corresponding with the hollow circle punch intersecting interface  130  at these six points. Although a three sided dovetail has been described and illustrated, it will be recognized by one skilled in the pertinent art that an ovalized dovetail (See  FIG. 9 ) or polygonal dovetail having more than three sides (e.g., four or more, see  FIG. 10 ) is also contemplated. In each case, a generously radiused dovetail is contemplated with a hollow circle punch to be used for swaging. It will also be recognized that the alternative embodiments illustrated in  FIGS. 9 and 10  both provide six swaging contact points. 
   In this manner, retention in an x and y directions is seen as at least doubled compared with the cross pattern punch profile illustrated in  FIG. 7  because the circle punch profile provides twice the edge swaging contact points (i.e., 6 vs. 3). Accordingly, a stronger bond results without welding, thus eliminating touch-up to cover burn marks associated with welding. The circular punch profile enhances the bond by distributing the load more uniformly around the generously radiused dovetail features. 
   While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.