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Publication numberUS3581366 A
Publication typeGrant
Publication dateJun 1, 1971
Filing dateDec 9, 1968
Priority dateDec 9, 1968
Publication numberUS 3581366 A, US 3581366A, US-A-3581366, US3581366 A, US3581366A
InventorsArnold Gottlieb, George A Majesko
Original AssigneeDriver Co Wilbur B
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Thermostatic bimetal
US 3581366 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

June l, 1971 A, GOTTUEB ETAL 3,581,366

THERMOSTATIG BIMETAL Filed Dec. 9, 1968 .fda

ATTORNEY United States Patent O 3,581,366 THERMOSTATIC BIMETAL Arnold Gottlieb, Colonia, and George A. Maiesko, Glen Ridge, NJ., assgnors to Wilbur B. Driver Company Filed Dec. 9, 1968, Ser. No. 782,070 Int. ICl. B32b 15/00 U.S. Cl. 29-195.S 2 Claims ABSTRACT F THE DISCLOSURE A thermostatic bimetal having enhanced temperature dependent characteristics such as the amount and linearity of deflection and developed force as Well as an extended temperature range of maximum sensitivity. The bimetal employs a low expanding component containing, as major constituents, 30.75 %31.75 by weight of nickel, 6.5%- 8.5% of cobalt, balance iron. This component can also contain, as minor constituents, manganese, carbon and silicon.

SUMMARY OF THE INVENTION All thermostatic bimetals possess certain important characteristics which are functions of temperature; i.e., the amount and linearity of deflection, the amount and linearity of developed force, and the range of maximum sensitivity. (This range is the temperature range of maximum rate of change of deflection and force.) All of these characteristics are related to Aa, which is the diierence between the coeflicients of thermal expansion of the high and the low expanding components of the bimetal. The standard low expanding component is Invar, which uses two major constituents, nickel (36% by weight) and iron.

In contradistinction, We employ as a low expanding component an iron-nickel-cobalt alloy having the following composition, by weight:

Percent Nickel 30.75-31.75 Cobalt 6.5-8.5 Iron Balance In addition, this alloy can contain 0.05%0.50% of manganese and .015%0.12% of carbon. Further, this alloy can also contain .015%-0.15% of silicon. The Aa attained from thermostatic bimetals using this alloy is larger than any other bimetals using Invar and moreover, the linearity of Aa is maintained within desired limits over a greater temperature range. As a result, our bimetal, for a given temperature range, is characterized by enhanced magnitude and linearity of both force and deflection as well as an extended range of maximum sensitivity.


FIG. 1 is a perspective View of a bimetal in accordance with our invention; and

FIG. 2 is a graph comparing 4the change of Aa with ternperature of certain of our bimetals as compared to a bimetal using Invar.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 shows a typical bimetal in accordance with our invention having two bonded layers and 12. Layer 10 is a conventional high expanding component such as chromium-nickel-iron. Layer 12 is a low expanding component in accordance with our invention.

The overall composition ranges of the major constitu- 3,581,366 Patented June l, 1971 ents of this low expanding component as expressed in percent by weight are:

The ranges of the minor constituents of this component are:

Percent Manganese 0.05-0.50 Carbon 0.015-0.12 Silicon 0.0150.15

No special processing is required in using this alloy together with other bimetal alloys as compared to using standard Invar. Conventional hot and cold bonding techniques may be used together with standard annealing and cold rolling procedures.

The important thermostatic bimetal characteristics of curvature (reciprocal of radius of curvature), deection and force are functions of Aa (the difference in expansion coeicients of the high and low expanding elements), as Well as the thicknesses of these components and the ratio of the elastic moduli of the low expanding and high expanding components. Since the modulus of our low expanding alloy is approximately the same as that of standand Invar and the thickness is a design consideration only, Aa is the most important parameter.

A known bimetal using Invar as the low expanding component and a known nickel-chromium-iron high eX- panding component (typical composition 22% by weight of chromium, 3% nickel, balance iron) was prepared, and its Aa was measured and plotted as a function of temperature as shown at curve 20 in FIG. 2.

Two rbimetals using the same high expanding component and two different compositions of our low expanding alloy were prepared and the two different Aas were measured and plotted as a function of temperature as Shown at curves 22 and 24 respectively in FIG. 2.

The low expanding alloy used in obtaining curve 22 had the following composition:

Nickel 31.29

Cobalt 7.05 Manganese 0.10 Carbon 0.03 7

Silicon 0.10

The low expanding alloy used in obtaining curve 24 had the following composition:

Nickel 31.54 Cobalt 8.16 Manganese 0.07 Carbon 0.016 Silicon 0.10

It can be seen that the Aa for each of curves 22 and 24 is not only larger `than that for curve 20, Ibut is also more nearly constant with increasing temperature. Note that curves 22 and 24 have a spread in Aix of .50X 10H6/ F. and .20 l06/ F. respectively as compared to a spread of .90X106/ F. for curve 20 over the temperature range of 10W-500 F.

The flexivity coecient is a fundamental parameter for evaluating bimetal characteristics. It is the temperature coefficient of curvature dened as:

e-at F: R. R1


F=Flexivity R1=Radius of curvature at temperature T1 R2=Radius of curvature at temperature T2 t=Thickness of bimetal The following table compares the flexivity coeicients that can be obtained with Ithe compositions such as used for curves 22 and '24 as compared with the known composition of curve 20. The temperature range for flexivity measurement is 100 F.300 F. and the two components have equal thicknesses.

FLEXIVITIES [Parts per million per degree E] Over the temperature range of 100 F.-300 F.

Curve 20 14.6 Curve 22 15.7, Curve 24 15.3

Greater increases in flexivity can be obtained when high expanding elements having lower expansion coefficients than that used herein are coupled without low expanding alloy.

As a result, our bimetals, as compared to known bi- -metals, are characterized by:

Within the normal operating temperature range of bimetals, the composition ranges given herein result in the optimization of Aa and the temperature range of maximum sensitivity.

While we have described our invention with particular reference to preferred embodiments, our protection is to be limited only yby the scope of the claims which follow.

What is claimed is: 1. A thermostatic bimetal comprising: rst and second metallic layers bonded together tol deine a strip, the rst layer being a high expanding alloy, the second layer being a low expanding alloy, said strip being characterized by a parameter, Aa, which is the difference between the thermal c0- efcients of expansion of the two layers, said parameter having a substantially constant value over a temperature range of F. to 300 F. and being in excess of 1.01 l0'I per F. throughout this range;

said first layer consisting essentially of nickel, chromium and iron;

said second layer consisting essentially of the following as expressed in percent by weight:

Percent Nickel 30.75-31.75 Cobalt 6.5-8.5 Manganese 0.05-0.5 Carbon 0.015-0.l2 Silicon 0.015-0.15


Iron Balance 2. A bimetal as set forth in claim 1 wherein the first layer consists essentially of 22% chromium, 3% nickel, balance iron.

References Cited UNITED STATES PATENTS 1,604,064 10/1926 Miller 29-l95.5 1,689,814 10/1928 Brace 29-l95.'5 2,941,882 6/1960 Franklin 75-123 HYLAND BIZOT, Primary Examiner gg@ UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 :581,366 Dated June l, 1971 Inventor) Arnold Gottlieb and George A. Ma'jesko It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column l, line 34 of the specification (.36Z, by weight) should read(36Z, by weght).

Signed and sealed this 21 st day of' December 1 971 (SEAL) Attest:

EDWARD M.FLETGHER,JR3JR. ROBERT GOITSCHALK` Attestng Officer Acting Commissioner of' Patents

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3765846 *Apr 17, 1972Oct 16, 1973Chace Co W MThermostatic bimetals
US4366460 *Mar 13, 1980Dec 28, 1982Kernforschungszentrum Karlsruhe GmbhSpring elements for supporting a superconductive coil
US5573860 *May 5, 1994Nov 12, 1996Sumitomo Special Metals Co., Ltd.Bimetal
CN103207204A *Jan 12, 2012Jul 17, 2013宝山钢铁股份有限公司Standard sample used for detecting specific thermal deflection property and its preparation method
EP0659548B1 *May 5, 1994Jul 18, 2001Sumitomo Special Metals Company LimitedBimetal
U.S. Classification428/616, 374/E05.39, 428/682
International ClassificationC22C38/10, G01K5/66, B32B15/01
Cooperative ClassificationG01K5/66, H01H2037/526, B32B15/011, C22C38/105
European ClassificationB32B15/01B, G01K5/66, C22C38/10B
Legal Events
Jul 26, 1984AS02Assignment of assignor's interest
Effective date: 19840427
Jul 26, 1984ASAssignment
Effective date: 19840427