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US 4,050,976 AGranted
Strain gage application
AssigneeBofors America, Inc.
InventorLudvigs O. Reiters
Life of this patent
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AssigneeBofors America, Inc.
InventorLudvigs O. Reiters
Estimating the term…
Electrical-resistance strain gages, particularly those of foil construction, are advantageously pre-packaged as conveniently-manipulatable and protected sub-assemblies in which the metal gage grid and its tabs are sandwiched between a flexible tape coated with a tacky adhesive and a partly-cured thin layer of fiber-reinforced resin, the resin layer and exposed portions of the adhesive-coated tape in turn being protected by a removable polytetrafluorethylene cover sheet; bonding of the gage to a measurement specimen is achieved without conventional cementing by removing the cover sheet, abutting the resin layer with a selected surface of the specimen, heating the layer while pressing against the tape to force the gage partly into the layer and to force the layer against the specimen surface, and stripping the tape after the resin has cured, thereby leaving the gage in a firmly-bonded close proximity with the specimen surface, separated therefrom only by a thinned layer of fiber-reinforced resin which also locks with the gage filaments partly embedded within that layer.
In the preparation of a strain-gage, a method for application of fine electrically-conductive metallic foil grids in uncemented attachment to a specimen surface, comprising the steps of supporting a metallic foil grid upon a flexible backing, adhering the thus-supported grid to a tacky surface of a pressure-sensitive flexible tape, removing the backing, replacing the backing with a flexible layer less than about 0.001 inch thick and consisting essentially of a partly-cured fiber-reinforced thermosetting resin, placing and pressing the outer surfaces of the resin layer against a desired surface to which the grid is to be bonded while the tape and grid adhere, effecting a final curing of the resin layer which hardens the same while bonding it both to the desired surface on one side and to the grid on the other, and stripping the tape to expose the grid after the resin layer is sufficiently hardened by curing to bond securely with the grid.
Dependencies are inferred from the claim text.