GB723370A - Improvements in strain gauges - Google Patents

Abstract

723,370. Resistance strain gauges. JONES, H., and BRITISH CELANESE, Ltd. June 30, 1953 [July 2, 1952], No. 16655/52. Class 40 (1) A woven-ribbon type strain gauge for use at elevated temperatures consists wholly of wire and other heat-refractory material. The ribbon, Fig. 1, comprises a warp of glass fibre yarns 4 woven in a plain weave with a weft 5 consisting of a resistance wire 7 braided with four glass-fibre yarns 8. After weaving, the ribbon is annealed, by raising it to a temperature of 400‹C. approxmately and then slowly cooling, to prevent the weft from springing out of position when the ribbon is cut into lengths to form strain gauges which are secured to the articles to be tested by a heat-resisting cement, e.g. Quigley's Blue 1925 Cement. Alternatively, the weft may be bare wire, the warps and the cement being relied on for insulating purposes. To facilitate weaving in such a case, the wire may be initially. covered with a lapping of cellulose acetate yarn which is dissolved from the woven ribbon by acetone. The resistance wire used is less than 0.0032 inch diameter and may be of nickel-chrome alloy. Fibreglass glass yarns, or, for higher temperatures, the continuous glass yarn known as " Refrasil " may be used. As described in Specification 647,377, [Group IX], the ribbon may be woven in sections Fig. 2, at each end of which a projecting loop 9 of the wire containing weft is formed at the ribbon edge to serve the attachment of terminals when the ribbon is cut at 11. Specification 623,641, [Group IX], also is referred to.