US3765846A

US3765846A - Thermostatic bimetals

Info

Publication number: US3765846A
Application number: US00244531A
Authority: US
Inventors: A Gottlieb; G Majesko
Original assignee: W M CHACE CO
Current assignee: Pulse Electronics Corp; W M CHACE CO
Priority date: 1972-04-17
Filing date: 1972-04-17
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16
Also published as: CA983216A

Abstract

A thermostatic biemetal having a relatively high deflection is disclosed. The bimetal comprises as a high expanding side a manganese-nickel-copper alloy having specific ranges for nickel and the combined total of copper and one-half the nickel content is also within specific limits. The low expanding side is a nickel-iron-cobalt alloy with controlled amounts of manganese carbon and silicon.

Description

United States Patent Gottlieb et al.

[ Oct. 16,1973

2,349,577 5/1944 Dean 29/1955 3,581,366 6/1971 Gottlieb ..29/195.5

Primary Examinerl-lyland Bizot Attorney-Norman J. OMalley et a1.

[57] ABSTRACT A thermostatic biemetal having a relatively high deflection is disclosed. The bimetal comprises as a high expanding side a manganese-nickel-copper alloy having specific ranges for nickel and the combined total of copper and one-half the nickel content is also within specific limits. The low expanding side is-a nickel-iron-cobalt alloy with controlled amounts of manganese carbon and silicon.

2 Claims, 1 Drawing Figure I6 /\BIMETAL OF THIS INVENTION PRIOR ART BIMETAL TEMPERATURE "F 1 THERMOSTATIC BIMETALS CROSS-REFERENCE TO RELATED APPLICATIONS Co-pending patent application Ser. No. 244,530, 5 filed Apr. 17, 1972, discloses'the high expanding alloys used in this invention and filed concurrently herewith. Those alloys, however, can be used in other uses.

BACKGROUND OF THE INVENTION This invention relates to thermostatic bimetals. More particularly it relates to a thermostatic bimetal having an extremely higher deflection.

Thermostatic bimetals have long used a 36 Ni balance iron alloy as a low expanding alloy and the most common high expanding alloys were the Mn-Ni-Cu alloy containing from about 16 to 18 percent copper and about percent nickel because it was believed these alloys had the maximum degree of thermal expansion of any of the alloys of the Mn-Ni-Cu system. These bimetals have a specific deflection of about 0.20 X 10 /C to 0.21 X lO/C when tested in the temperature range of from about 20C to about 130C.

The Mn-Ni-Cu alloys disclosed and claimed in the before-mentioned co-pending application result in a larger deflection when used with the traditional 36 percent nickel balance iron alloys known as INVAR than the prior art combination of INVAR and Mn 10 Ni l618 Cu. It is believed, however, that a bimetal that has an even higher deflection would be an advancement in the art.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of this invention to provide a bimetal having a high deflection.

It is another object of this invention to provide a bimetal which will yield the same amount of deflection with appreciably less length.

It is still another object of this invention to provide a bimetal which has a specific deflection of greater than 0.23 X 10/C when measured in the temperature range of from 20 to 130C.

These and other objects are achieved in one aspect of this invention which comprises a bimetal having as its high expanding side an alloy consisting essentially of from about 15.5 percent to about 22.5 percent by weight of nickel, the sum of the percent of weight of copper and one-half of the percent by weight of nickel being from about 13.75 percent to about 16.75 percent and the balance manganese. The foregoing high expanding alloy is used in conjunction with a low expanding alloy having the following constituents in percent 55 by weight:

BRIEF DESCRIPTION OF THE DRAWING The drawing is a graph which shows the differences in coefficient of expansion between the high and low expanding elements of a prior art bimetal and the bimetal of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above description of some of the aspects of the invention.

A typical thermostatic bimetal is sold by W. M. Chace and designated as Chace 6650. This bimetal consists of a high expanding alloy of 72% Mn, 10% Ni and 18% Cu and a low expanding alloy of 36% nickel, balance iron. The specific deflection is about 0.202 X l0/C. The specific deflection is obtained on a standard dimension of a bimetal such as 1 mm thick X mm long and heated over the temperature range of from 20C to C. The deflection is determined by clamping one end and measuring the deflection of the other end. The deflection is dependent primarily upon the difference in the coefficients of expansion of the materials.

It has been found that the bimetals of this invention yield a high specific deflection of at least 0.23 X 10/C over the foregoing temperature range. This enables less length of metal to be used to get the same deflection. The high expanding alloy consists essentially of from about 15.5 to about 22.5 percent by weight of nickel, the sum of the copper content in percent by weight and one-half the nickel content in percent by weight within the range of 13.75 to 16.75 and the balance manganese. Preferred alloys within the foregoing ranges are those that contain from about 15.5 percent to about 18.5 percent by weight of nickel. The coefficient of expansion of these alloys is greater than about 30.0 ppm/*C.

The low expanding alloys are iron, nickel and cobalt alloys containing specific amounts of manganese, carbon and silicon. These alloys are further characterized by having narrow ranges of each component that is from 30.75 to 31.75 percent by weight nickel, 6.5 to 8.5 percent cobalt and balance iron. Manganese varies between 0.05 to 0.5 percent, carbon from 0.015 to 0.12 percent and silicon from 0.015 to 0.15 percent.

The difference in the coefficients of expansion in the alloys used in the bimetals of this invention as compared with the prior art bimetal is shown in the drawing over the range of 100 to 290F. As can be seen, for all temperature values shown the differences which relate directly to deflection are appreciably greater for the bimetal of this invention. For example, the differences of the expansion metal used in the bimetals of this invention are about 3.5 to 3.8 ppm/C greater than those of the metals used in prior art bimetals in the 200 to 400F range.

While there has been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. A bimetal comprising a high expanding side of an alloy consisting essentially of from about 15.5 to about 22.5 percent by weight of nickel, the sum of the copper content in percent by weight and one-half the nickel content in percent by weight being from about 13.75 to about 16.75 percent and the balance manganese, and f metallurgically bonded to a common interface of said 23 13::

high expanding side, a low expanding side of an alloy consisting essentially of in percent by weight: 2. A bimetal according to Claim 1 having a specific 5 deflection of at least about 023 X lO/C within the nickel 30-75 to 31-75 temperature range of from about to about 130C. cobalt 6.5 to 8.5

manganese 0.05 to 0.5

Claims

2. A bimetal according to Claim 1 having a specific deflection of at least about 0.23 X 10 4/*C within the temperature range of from about 20* to about 130*C.