A Shear and Form Scheme for Grounding Adjacent Sheet Metal Layers
Publication Date: 2009-May-01
The IP.com Prior Art Database
A novel sheared and formed sheet metal feature residing on a middle layer provides a "bite" into the outside layers as a star washer would. This features consists of "teeth", the size and number of which are determined by the appropriate sheet metal thickness and the application. Since the feature is present in the sheet metal, none of the difficulties usually encountered when using a star washer are involved.
In chassis and enclosure designs for electronic devices and instrumentation it is sometimes necessary to provide reliable and consistent grounding to help provide shielding from electromagnetic interference. To provide a reliable and consistent ground it is necessary for adjacent electrically-conductive components to mate over a region that is free of non-conducting oxides and is sealed from an atmosphere where an oxide layer can form. For example, the head of a screw bears down upon an aluminum sheet metal part in an area adjacent to the hole the screw passes through. When the head contacts the metal, an oxide layer is wiped away from the sheet metal, the force of the screw head provides the seal from the atmosphere. A similar wiping action takes place between the screw threads and the threads of a sheet metal insert. A reliable and consistent ground path is formed from the top layer, through the screw head, through the mating threads of the insert, to the bottom sheet metal part.
For a stack of 3 or more sheet metal layers the head or threads will not interface the middle layer(s). One method of providing that interface would be the introduction of a “star” washer commonly found in the marketplace. However, the handling required during assembly can be problematic in terms of the time to install, the difficulty in positioning the washer during assembly, the expense of the washer, and the risk that the washer could be forgotten. This invention utilizes a...