Apparatus for Apertured Attachment of Metal Sheets

Abstract

Apparatus attaches together stacked upper and lower metal sheets and provides a reinforced aperture. A lower die has a die groove and an opening in the center of the die groove. An upper die has an annular end face that registers with the die groove and a spring-loaded reciprocable punch button that registers with the opening. A hollow ring-shaped grommet has an annular upper end flange engaged by the annular end face of the upper die and an axially extending tubular wall longer than the stacked thickness of the sheets. A metal piercing point at the terminal end of the axially extending wall pierces through the stacked upper and lower sheets and into engagement with the die groove of the lower die to progressively bend the axially extending wall radially outward and upward into engagement with the lower sheet, thereby attaching the sheet together and providing a reinforced aperture.

1 . Apparatus for attaching stacked upper and lower metal sheets comprising:
 a lower die having a die groove that underlies the lower sheet and an opening in the center of the die groove;   an upper die having an annular end face that overlies the upper sheet and registers with the die groove of the lower die;   a spring-loaded punch button that is reciprocable within the upper die and registers with the opening in the lower die; and   a ring-shaped grommet having an annular upper end flange for engagement by the annular end face of the upper die and an axial extending wall of greater length than the stacked thickness of the upper and lower metal sheets, said axial extending wall having a metal piercing point at the terminal end thereof so that upon lowering of the upper die the annular end face forces the metal piercing point to pierce through the stacked upper and lower sheets and into engagement with the die groove of the lower die to bend the axial extending wall radially outward and upward to engage with the lower sheet whereby the sheets are attached together by capture between the annular upper end flange and the outward bent axial extending wall and the hollow ring shape of the grommet provides an aperture through the attached together sheets.   
     
     
         2 . The apparatus of  claim 1  further comprising said spring-loaded punch having a dome shaped end face that engages the top sheet and bends the severed portions of the upper and lower sheets for disposal through the opening in the center of the lower die surface. 
     
     
         3 . The apparatus of  claim 1  further comprising said lower die having a circumferential knife edge that registers with the metal piecing point of the grommet to aid in severing the discs. 
     
     
         4 . The apparatus of  claim 3  further comprising said circumferential knife edge having a bevel that deflects the axial extending wall of the grommet radially outward upon the severing of the metal discs. 
     
     
         5 . The apparatus of  claim 1  further comprising said opening of the lower die being a stepped bore having an upper portion that is of a diameter to receive the punch and a lower chute portion that is of a diameter greater than the diameter of the punch face to facilitate the disposal of the severed discs. 
     
     
         6 . The apparatus of  claim 5  further comprising said spring-loaded punch having a dome shaped end face that engages the top sheet and bends the severed portions of the upper and lower sheets for disposal through the opening in the center of the lower die surface. 
     
     
         7 . Apparatus for attaching stacked upper and lower metal sheets comprising:
 a lower die having a die groove that underlies the lower sheet and an opening in the center of the die groove, said opening being a stepped bore including an upper bore portion and a lower chute portion of greater diameter than the upper bore portion;   an upper die having an annular end face that overlies the upper sheet and registers with the die groove of the lower die and a central bore that overlies the opening of the lower die;   a punch reciprocable within the central bore of the upper die;   a coil compression spring urging the punch to an extended position extending beyond the annular end face of the upper die;   a grommet seated on the punch and having an annular upper end flange driving the annular end face of the upper die and an axial extending wall of greater length than the stacked thickness of the upper and lower metal sheets, said axial extending wall having a metal piercing point at the terminal end thereof so that upon lowering of the upper die the annular end face forces the metal piercing point to pierce through the stacked upper and lower sheets and into engagement with the die groove of the lower die to bend the axial extending wall radially outward and upward to engage with the lower sheet whereby the sheets are attached together by capture between the annular upper end flange and the outward bent axial extending wall.   
     
     
         8 . The apparatus of  claim 7  further comprising said opening of the lower die being a stepped bore having an upper portion that is of a diameter to receive the punch and a lower chute portion that is of a diameter greater than the diameter of the punch face to facilitate the disposal of the severed discs. 
     
     
         9 . The apparatus of  claim 8  further comprising said spring-loaded punch having a dome shaped end face that engages the top sheet and bends the severed portions of the upper and lower sheets for disposal through the opening in the center of the lower die surface. 
     
     
         10 . The apparatus of  claim 7  further comprising said lower die having a circumferential knife edge that registers with the metal piecing point of the grommet to aid in severing the discs. 
     
     
         11 . The apparatus of  claim 10  further comprising said circumferential knife edge having a bevel that deflects the axial extending wall of the grommet radially outward upon the severing of the metal discs. 
     
     
         12 . The apparatus of  claim 7  further comprising said grommet being a hollow ring shape so that upon installation of the grommet to attach together the stacked sheets, a reinforced aperture is simultaneously provided through the sheets. 
     
     
         13 . The apparatus of  claim 7  further comprising said spring-loaded punch having a dome shaped end face that engages the top sheet and bends the severed portions of the upper and lower sheets for disposal through the opening in the center of the lower die surface. 
     
     
         14 . Apparatus for attaching stacked upper and lower metal sheets comprising:
 a lower die having a circumferential extending knife edge extending upwardly, a circumferential die groove located radially outward from and surrounding the knife edge, and an opening located radially inward from the knife edge;   an upper die having an annular end face that overlies the upper sheet and registers with the die groove of the lower die;   a punch button that is reciprocable within the upper die and registers with the opening in the lower die;   a coil compression spring acting to urge the punch button to an extended position from the upper die in which the punch button extends into the opening in the lower die; and   a ring-shaped grommet having a hollow interior receiving the punch button, an annular upper end flange for engagement by the annular end face of the upper die, and an axial extending wall of greater length than the stacked thickness of the upper and lower metal sheets, said axial extending wall having a metal piercing point at the terminal end thereof that registers with the knife edge of the lower die so that upon lowering of the upper die the annular end face forces the metal piercing point to pierce through the stacked upper and lower sheets and be deflected by the die groove of the lower die to bend the axial extending wall radially outward and upward to engage with the lower sheet whereby the sheets are attached together by capture between the annular upper end flange and the outward bent axial extending wall and the hollow ring shape of the grommet provides a reinforced aperture through the attached together sheets.   
     
     
         15 . The apparatus of  claim 7  further comprising said spring-loaded punch having a dome shaped end face that engages the top sheet and bends the severed portions of the upper and lower sheets for disposal through the opening in the center of the lower die surface. 
     
     
         16 . The apparatus of  claim 14  further comprising said opening of the lower die being a stepped bore having an upper portion that is of a diameter to receive the punch and a lower chute portion that is of a diameter greater than the diameter of the punch face to facilitate the disposal of the severed discs. 
     
     
         17 . The apparatus of  claim 16  further comprising said spring-loaded punch having a dome shaped end face that engages the top sheet and bends the severed portions of the upper and lower sheets for disposal through the opening in the center of the lower die surface.