Patent Publication Number: US-2012042711-A1

Title: Panel screw clinching anvil

Description:
BACKGROUND 
     Panel screws are typically used to attach metallic sheets or panels to larger assemblies. These screws are typically inserted through holes in the panels and threaded into some sort of threaded female fastener. Sometimes it is desirable to affix the screw to the panel to improve efficiency during assembly or to prevent loss during disassembly. 
     One such product is the SCB Spinning Clinch Bolt, made and sold by Penn Engineering. This is a one-piece fastener that has a circular shoulder under the screw head that, when pressed into a hole in the metallic sheet, deforms the material around the hole thereby causing the hole diameter to decrease in size to smaller than the screw thread outside diameter, thus preventing the screw from being removed. 
     However, the SCB fastener has a specialized head configuration and is made from heat-treated steel specific for this application. Thus, the SCB fastener is not suitable for the wide variety of panel screws commonly available in the trade utilizing different head configurations and materials. Further, after installation, the SCB fastener creates an unsightly dent on the visible side of the sheet. 
     It would be desirable to have a system for clinching a panel screw to a panel that will work with any style screw head or material similar in hardness to the panel sheet material. Further, it would be desirable to hide any material deformation caused by such a fastener. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a clinching anvil. 
         FIGS. 2A-2C  illustrate a sequence for using the anvil of  FIG. 1  in a press. 
         FIGS. 3A-3J  illustrate alternative embodiments of clinching anvils. 
         FIG. 4  illustrates a c-press. 
     
    
    
     DETAILED DESCRIPTION 
     Several embodiments of a clinching anvil are described. The clinching anvil is used to provide a rigid base against which a punch may be pressed. In this case, the punch is used to apply pressure to a fastener inserted into an opening in a panel against the rigid anvil. The anvil includes an opening and a recess into which the fastener moves, but also includes one or more raised ridges near the opening. When the punch is pressed down thereby forcing the fastener into the anvil recess, the ridges on the anvil deform the underside of the panel, thereby captivating the screw with the panel. 
     Referring now to  FIG. 1 , a perspective view of a clinching anvil  10  for use with panel screws is illustrated. The clinching anvil  10  is preferably formed from solid, heat-treated, lathe-turned carbon steel to be a solid body  12 . Although the body is shown as a cylindrical structure in this embodiment, other shapes may be adopted. A recessed area  14  is formed coaxially inside the body  12  with a circular opening  15  in one end of the body communicating with the recessed area for receiving a fastener, such as screw  20  (see  FIGS. 2A-2C ) into the recessed area. A lip portion  16  is formed as an annular ring with a raised profile immediately adjacent to the opening  15  on one end of the body  12 . The lip portion may comprise one or more rings or ridges having raised profiles on the end of the body  12 . The raised profile of the lip portion  16  deforms the underside of a panel when pressed together with a fastener as described herein. 
     Referring now to  FIGS. 2A-2C , a sequence for installing a screw  20  into panel  30  is illustrated. 
     In  FIG. 2A , the screw  20  is first inserted by hand through hole  32  in panel  30  in preparation for pressing the screw into anvil  10 . The hole  32  in panel  30  should be slightly larger than the outside diameter of the screw threads  21 . Likewise, the opening  15  and recessed area  14  of the anvil  10  are similar in size, i.e., slightly larger than the outside diameter of screw threads  21 . It should be noted that anvil  10 , and in particular opening  15  and recessed area  14 , can be made in a wide variety of sizes corresponding to standard or custom panel screws. 
     In one embodiment, a c-shaped press  50  (see  FIG. 4 ) may be used for pressing, where the anvil  10  is held in the bottom chuck  51  of the press, and a punch  54  is held in the top chuck  52  of the press. The panel  30  is moved into position on the press  50  such that panel hole  32  aligns with the opening  15  of anvil  10 , and the screw  20  is fit through opening  15  into recess  14  of anvil  10 . Note in  FIG. 2A  that the lip  16  at the opening  15  of anvil  10  is raised in profile and therefore in position to be urged against the underside of panel  30  when the press  50  is operated. Further, the screw  20  includes a non-threaded shank portion  22  that permits axial float of the screw after installation. 
     The press  50  is operated by moving the top chuck  52  downward in the direction shown by arrow  53 , thereby exerting pressure from the punch  54  against the head  23  of screw  20  and forcing the screw and panel  30  against the anvil  10  held in the stationary bottom chuck  51 , as shown in  FIG. 2B . This pressure causes the lip  16  at the opening  15  of recess  14  to deform the underside of the hole  32  in panel  30  thereby effectively reducing the size of opening  32  such that the screw threads  21  can no longer pass through the opening  32 , as illustrated in  FIG. 2C . 
       FIGS. 3A-3L  illustrate alternative embodiments of the anvil. 
       FIGS. 3A-3B  illustrate the same embodiment as shown in  FIGS. 1-2 , wherein the anvil  10  includes circular opening  15  and lip  16  disposed adjacent the opening  15 . The lip  16  is actually an annular ridge formed to have a raised profile which comes to a sharp point at its apex approximately 0.020 inches above the surface  19  of the anvil  10 . Transition portions  111 ,  112  are formed with the ridge  16  on either side thereof. The total width of the ridge and transition portions is approximately 0.040 inches. The raised profile of the ridge  16  deforms the underside of panel  30  when pressed. 
     In  FIGS. 3C-3D , the anvil  210  includes opening  15 , but instead of adjacent lip  16 , this embodiment includes a series of discrete, straight ridges  216  disposed radially, for example, at 90 degree intervals around the opening  15 . The ridges  216  are formed to have a raised profile, for example, approximately 0.020 inches high above anvil surface  19  and 0.040 inches wide, which deforms the underside of panel  30  when pressed. 
     In  FIGS. 3E-3F , the anvil  310  includes opening  15 , and an annular ridge  316  that is disposed immediately adjacent opening  15 . A transition portion  317  provides a smooth transition from the top of the ridge  316  down to the surface  19  of the anvil  310 . The annular ridge  316  is formed to have a raised profile which deforms the underside of panel  30  when pressed. This configuration is similar to that shown in  FIGS. 3A-3B , but in this configuration, there is no transition portion between the ridge and the opening, and the raised profile of the ridge  316  is wider than that of ridge  216 . For example, the ridge  316  may be 0.04 inches wide across the top of the ridge, as opposed to lip  16  in  FIGS. 3A-3B , which comes to a point on top of the ridge. 
     In  FIGS. 3G-3H , the anvil  410  includes opening  15 , and an annular ridge  416  that is not disposed immediately adjacent opening  15 , but is separated from the opening by a transition portions  418  and  419 . Transition portion  418  provides a smooth angled transition from the top of ridge  416  down to transition portion  419 . Transition portion  419  provides a smooth flat transition to the opening  15 . Transition portion  417  provides a smooth angled transition from the other side of the ridge  416  down to the surface  19  of anvil  410 . The raised annular profile of ridge  416  deforms the underside of panel  30  when pressed. 
     Finally, in  FIGS. 3I-3J , the anvil  510  includes opening  15 , and an annular ridge  516  disposed near the opening  15 , with a transition portion  517  that provides a smooth transition from the top of ridge  516  to the opening  15 . The raised profile of ridge  516  is rounded off, but still deforms the underside of panel  30  when pressed. 
     In general, those skilled in the art to which this disclosure relates will recognize that changes in construction and materials will suggest themselves without departing from the spirit and essential characteristics of this disclosure. Accordingly, the disclosures and descriptions herein are intended to be illustrative, and not limiting, of the scope of the invention, which is set forth in the claims.