Apparatus for apertured attachment of metal sheets

The present invention relates to apparatus for attaching together stacked upper and lower metal sheets, and more particularly an attachment of metal sheets that simultaneously provides an aperture through the sheets.

It is well known in automotive and other manufacturing industries that two sheets of metal can be attached together by laying one sheet atop the other and then installing a fastener therebetween.

It is also known in the manufacturing industries to provide an aperture through a metal sheet, or through a stack of metal sheets, for various purposes such as providing an aperture for the drainage of water, or providing an aperture for receiving a locating pin to precisely locate the metal during the conduct of manufacturing processes such as stamping, or for precisely locating the sheet for measuring and gauging operations. It would be desirable to provide a new and improved apparatus by which metal sheets could be attached together, but at the same time a reinforced aperture could be provided through the sheets.

Apparatus is provided for attaching together stacked upper and lower metal sheets, while at the same time providing a reinforced aperture through the attached together sheets. A lower die is provided having a die groove that underlies the lower sheet and an opening in the center of the die groove. An upper die has an annular end face that overlies and registers with the die groove of the lower die. A spring-loaded punch button is reciprocable within the upper die and registers with the opening in the lower die. A ring-shaped grommet has an annular upper end flange for engagement by the annular end face of the upper die and an axially extending tubular wall of greater length than the stacked thickness of the upper and lower metal sheets. The axial extending wall of the grommet has a metal piercing point at the terminal end thereof so that upon lowering of the upper die, the annular end face of the upper die 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 progressively bend the axially extending wall radially outward and upward into engagement with the lower sheet. Thus the sheets are attached together by being captured between the annular upper end flange and the outward bent axially extending tubular wall. The hollow ring shape of the grommet provides an aperture through the attached together sheets and reinforces the aperture made through the metal sheets.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.