GB384673A - Thermostats - Google Patents

Abstract

384,673. Making thermostats. GENERAL PLATE CO., 34, Forest Street, Attleboro, Massachusetts, U.S.A. June 10, 1931, No. 16942. Convention date, June 26, 1930. [Classes 83 (ii) and 83 (iv).] Compound forms; corrugating; stamping.- A thermostatic unit comprises a sheet or annulus of composite thermostatic material, such as iron and brass or invar and monel metals, having corrugations running inwards from the periphery radially or otherwise, and having two positions of stable equilibrium with an intermediate position of unstable equilibrium and being adapted on reaching the critical temperature to snap from one position to the other. The preferred form is shown in Fig. 3, being an open-ended truncated cone with the corrugations around the central aperture deeper than around the outer edge, so that there is substantially the same amount of material at the inner edge as at the outer peripheral edge. Such a unit may be made by impressing the corrugations upon a cylindrical strip 14, Fig. 5, of the composite material by means of bevelled toothed rolls 15, 16 and then pressing out the corrugated strip in a die, Fig. 8, having one jaw with a conical recess and the other with a cylindrical recess, and repeating the operation with presses having jaws of differing slopes, and finally using a solid pressing member as shown in Fig. 10. The Specification as open to inspection under Sect. 91 states that the unit may be in the form of a substantially flat strip with transverse corrugations. It further states that a cylindrical strip may be corrugated by rolls without bevelling. This subject-matter does not appear in the Specification as accepted.