US1642485A - Bimetallic element - Google Patents

Description

Patented Sept. '13,-192 1 UNITED STATES wmuua '11.

CHACE, OI DETROIT, MICHIGAN, ASSIGNOR TO W. I. CHACE COMPANY, A CORPORATION OF MICHIGAN.

VALVE IBIHETALLIC ELEMIENT {Rom-swing. I

. lic element of high heat-resistant quality coupled with a comparatively high coeflicient of expansion welded into a nickel-steel element of low coefficient of expansion.

I am aware of various compositions of metal used in bimetallic elements for instance brass and nickel-steel alloy and, while this element is practicable up to tempera tures of about 4.50 degrees F., it becomes impracticable for use with higher temperatures. It is also necessary in apractical device for use under higher temperatures'to provide a metal having a coefiicient of expansion approximately equal to that of brass to secure an element readily -.responsive to temperature change. The element made of the two metals hereinafter described has this quality of ready responsiveness to temperature change-except that it is slow to ex- ,pand under temperatures below 200 degrees F., and is more readily responsive to higher degrees of temperatures. object of the invention to secure an element that is practically non-responsive or at least slow in responsiveness to temperatures below 200 degrees F. The bimetallic element herein described is useful wherever the element is subject to high temperatures as in making or'breaking the electric circuit in an electric hand iron or in the controlling of the valve in oil refining systems for internal combustion engines and various other places and mayhave any desired form either as a disk as is used in the electric hand iron or as an elongated strip asis used in an ordinary thermostat. depending upon the character of the apparatus with which it is used and the function it is to perform. With the electric hand iron the brass and iron bimetallic element is-practically useless due to the fact thatthe brass loses its elasticity at about 450 degrees E, which I have termed its critical temperature. This term as hereinafter used refers to the point beyond which the bimetallic element would become unreliable. With a structure in which brass forms one of the elements therefore it is impossible to utilize the same under temperature in excess of 450 degrees F., and in the electric hand iron the temperature thereof in use is approximately 600'degrees F.

For this purpos e sometimes metal'known as Monel metal has been used as one of the This also is an Application filed July 6, 1925. Serial in. 41,887.

elements in conjunction with the nickel-steel I alloy. The critical temperature of Monel metal, however,- is about 600 degrees F., and therefore it is not of. long life when used with an electric hand iron or other device wherein it is subject to such a temperature and furthermore requires too great a temperature change to cause movement of the element to the necessary extent.

One of the features of my improved bimetallic element is that its critical temperature is about 1200 degrees F., and is therefore useful. in a great many places where previous elements of another type of metal is impracticable or not of long life.

My improved bimetallic element consists of :a nickel-steel alloy in which the nickel content is from 36 to 42 per cent andwhich has a low coeflicient of expansion and the other element which I have utilized has a coeificient of expansion approximately equal to that of brassnamely, about .070 inches per foot.

Preferably my composition consists of Per cent. Carbon .50 Manganese .70 Silicon 1.75- Chromium -n 8.00 Nickel 22.00 Copper 2.00 Cobalt 1.00 Iron 64.05

In making my bimetallic element I Weld a bar of nickel-steel alloy and a bar of the 'above compositiontogether and roll the same to the desired thinness. From this sheet is cut the. element in the desired form either a disk or other shape as may be desired and 95 depending upon the purpose for which it is to be used. This is the usual practice in the making of a bimetallic element. With my bimetallic element one member of which has a high coeificientofexpansion formed of approximately the composition above stated and the other member of nickel-steel alloy I secure a bimetallic element as eflicient at high temperatures as is the usual brass such temperature, and further one that is .very slow to expand at temperatues below 200 degrees F. My new element at temperatures above 200 degrees F., is readily responsive to heat and is perfectly adapted for use in such places as in controllin circuits in an electric hand iron due to rapi responsiveness to temperatures around 600 de rees F., and which is affected readily by sight changes in temperature. In the usualMonel metal and steel alloy heretofore used with an electric hand iron a change of approximately 10 de rees in temperature is required to effect ma ring and breaking of circuit. With my composition the metal is responsive and will make and break the circuit within a range oi about 5 degrees F., it having a critical temperature of about 1200 degrees makes it very efiicient for use with the electric hand iron and in other places where the element is subjected to temperature up to 1200 degrees F., and without lo s of its elasticity.

A bimetallic element of the composition herein described will act approximately with equal rapidity to the previous brass and nickel-steel elements or nickel-steel and Monel metal above mentioned and when used with an electric circuit in the form of a disk the flexing of the disk is so rapid under variations in temperature than in breaking of the circuit no arcing occurs at the contacts.

I am aware of various compositions of metal used in bimetallic elements, and my invention consists not so much in the composition used as it does in the production of a bimetallic element characterized by its heat resistant quality and rapid expansion under temperatures above 200 degrees F., and its slowness to expand under temperatures below 200 degrees F., combined with a metal of much lower coefiicient of expansion having a high percentage of nickel. The two elements welded together form a bimetallic element having the stated qualitiesnamely, high heat resistant quality withstanding temperatures of practically 1200 degrees F., without impairing the clasticity of the element of high coefficient of expansion, is slow to respond to temperatures below 200 degrees F., and above such temperatures expands and contracts as readily as the usual brass and steel elements.

Having thus described my invention what I claim and desire to secure by Letters Paient of the United States is-- 1. A bimetallic element comprising two nemesis metal elements fused together, each of said elements retaining its elasticit at tem era tures as high as 1200 degrees one 0 said elements containing approximately forty per cent nickel and characterized'by havin a low coeiiicient of expansion, and the ot er of said elements being of a composition in which iron predominates and characterized by its havin a coeflicient of expansion of approximate y .070.at temperatures above two hundred degrees F.

2. A bimetallic element having as one of the said elements a nickel-steel alloy in which the nickel content is not greater than fortytwo per cent to which is welded a steel containing approximately the following compo sition- Carbon 3. A bimetallic element having as one of its members a metal approximately of the following composition- Carbon .50 Manganese .70 Silicon 1.75

' Chromium 8.00 Nickel 22.00 Copper 2.00 Cobalt 1. 00 Iron 64.05

and as the other member a metal oi a lower coefficient of expansion.

4. A bimetallic element consisting of two elements fused together. one of the elements being nickel steel alloy characterized by having a low coellicient of expansion and the other being of a composition of metals in which iron predominates and characterized by having a materially higher coeilicient of expansion and capable of retaining, its e1asticity at a temperature as high as twelve hundred degrees F., and being most rapidly expandible through a working range of from five hundred to seven hundred degrees F.

In testimony whereof, l sign this specitication.

WILLIAM M. canon.