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US3581366A - Thermostatic bimetal - Google Patents

Thermostatic bimetal Download PDF

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US3581366A
US3581366A US782070A US3581366DA US3581366A US 3581366 A US3581366 A US 3581366A US 782070 A US782070 A US 782070A US 3581366D A US3581366D A US 3581366DA US 3581366 A US3581366 A US 3581366A
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Prior art keywords
bimetal
nickel
temperature range
alloy
component
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US782070A
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Arnold Gottlieb
George A Majesko
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Carpenter Technology Corp
Wilbur B Driver Co
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Wilbur B Driver Co
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01KMEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K5/00Measuring temperature based on the expansion or contraction of a material
    • G01K5/48Measuring temperature based on the expansion or contraction of a material the material being a solid
    • G01K5/56Measuring temperature based on the expansion or contraction of a material the material being a solid constrained so that expansion or contraction causes a deformation of the solid
    • G01K5/62Measuring temperature based on the expansion or contraction of a material the material being a solid constrained so that expansion or contraction causes a deformation of the solid the solid body being formed of compounded strips or plates, e.g. bimetallic strip
    • G01K5/64Details of the compounds system
    • G01K5/66Selection of composition of the components of the system
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00Layered products comprising a layer of metal
    • B32B15/01Layered products comprising a layer of metal all layers being exclusively metallic
    • B32B15/011Layered products comprising a layer of metal all layers being exclusively metallic all layers being formed of iron alloys or steels
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/10Ferrous alloys, e.g. steel alloys containing cobalt
    • C22C38/105Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00Thermally-actuated switches
    • H01H37/02Details
    • H01H37/32Thermally-sensitive members
    • H01H37/52Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H2037/526Materials for bimetals
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/125Deflectable by temperature change [e.g., thermostat element]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771Transition metal-base component
    • Y10T428/12861Group VIII or IB metal-base component
    • Y10T428/12951Fe-base component
    • Y10T428/12958Next to Fe-base component

Definitions

  • 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.
  • 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.
  • FIG. 2 is a graph comparing 4the change of Aa with ternperature of certain of our bimetals as compared to a bimetal using Invar.
  • 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.
  • 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 important thermostatic bimetal characteristics of curvature 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.
  • the low expanding alloy used in obtaining curve 22 had the following composition:
  • the low expanding alloy used in obtaining curve 24 had the following composition:
  • curves 22 and 24 are 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:
  • FLEXIVITIES [Parts per million per degree E] Over the temperature range of 100 F.-300 F.
  • bimetals as compared to known bi- -metals, are characterized by:
  • composition ranges given herein result in the optimization of Aa and the temperature range of maximum sensitivity.
  • a thermostatic bimetal comprising: rst and second metallic layers bonded together tol define 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:
  • Iron Balance 2 A bimetal as set forth in claim 1 wherein the first layer consists essentially of 22% chromium, 3% nickel, balance iron.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Details Of Measuring And Other Instruments (AREA)

Abstract

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 CONSTITUENT, 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.

Description

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.
BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:
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
where:
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
and
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
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3765846A (en) * 1972-04-17 1973-10-16 Chace Co W M Thermostatic bimetals
JPS5138075A (en) * 1974-09-27 1976-03-30 Nhk Spring Co Ltd HISENKEINETSUTOKUSEIOJUSURUTAINETSUBAIMETARU
US4366460A (en) * 1979-03-16 1982-12-28 Kernforschungszentrum Karlsruhe Gmbh Spring elements for supporting a superconductive coil
US5573860A (en) * 1993-12-27 1996-11-12 Sumitomo Special Metals Co., Ltd. Bimetal
CN103207204A (en) * 2012-01-12 2013-07-17 宝山钢铁股份有限公司 Standard sample used for detecting specific thermal deflection property and its preparation method

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3765846A (en) * 1972-04-17 1973-10-16 Chace Co W M Thermostatic bimetals
JPS5138075A (en) * 1974-09-27 1976-03-30 Nhk Spring Co Ltd HISENKEINETSUTOKUSEIOJUSURUTAINETSUBAIMETARU
US4366460A (en) * 1979-03-16 1982-12-28 Kernforschungszentrum Karlsruhe Gmbh Spring elements for supporting a superconductive coil
US5573860A (en) * 1993-12-27 1996-11-12 Sumitomo Special Metals Co., Ltd. Bimetal
EP0659548B1 (en) * 1993-12-27 2001-07-18 Sumitomo Special Metals Company Limited Bimetal
CN103207204A (en) * 2012-01-12 2013-07-17 宝山钢铁股份有限公司 Standard sample used for detecting specific thermal deflection property and its preparation method
CN103207204B (en) * 2012-01-12 2015-03-11 宝钢特钢有限公司 Standard sample used for detecting specific thermal deflection property and its preparation method

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Effective date: 19840427