US1931251A - Torsion-spring for clocks, watches, etc. - Google Patents

Description

Patented Oct. 1"], 1933 UNITED STATES TORSION -SPR1NG FOR CLOCKS, WATCHES,

ETC.

Thomas H. Chamberlain, New Haven, Conn., as-

' signor to The New Haven Clock Company,

New Haven, Conn., a corporation No Drawing. Application March 17, 1930 Serial No. 436,650

2 Claims. (Cl. 75-1) This invention relates to an improvement in torsion-springs for various measuring or indicating instruments-of precision, such as clocks, watches, ammeters, .voltmeters, and other in- 5 struments in which a variation in the modulus of elasticity of the torsion-springs, due to, thermal changes, is a factor affecting accuracy.

The main object of my invention is to produce a torsion-spring which will have a substantially-uniform modulus of elasticity throughout the normal range of atmospheric temperatures, whereby thermal changes will not appreciably affect the precision of the readings of an instrument in which my improved torsionspring is installed.

A further object of my invention is to produce a torsion-spring having a substantially-uniform modulus of elasticity throughout the normal range of atmospheric temperatures, and which 0 is sufliciently ductile to be readily drawn, rolled,

or otherwise formed and shaped.

A further object of my invention is to produce a torsion-spring characterized as above which will be highly resistant to corrosion.

With the above and other objects in view, as will appear from the following, my invention consists in a torsion-spring having a substantially-uniform modulus of elasticity throughout the normal range of atmospheric temperatures and consisting of an alloy hereinafter described.

My improved torsion-spring is preferably made from a ferrous alloy of the following composi- 'tion:

Per cent Carbon 0. 15 to 0. 17 Manganese 0. 70 to 0. 90 Silicon 0. 65 to 0. 80 Nickel 35. 50 to 36. 50 Chromium 12. 00 to 13. 00

Iron to form the balance after a suitable allowance for impurities, such as sulphur, phosphorous, etc. 7

The carbonand manganeseand siliconcontent set forth above act as hardeners, and

while they, in the aggregate, are appreciably high, it will be noted that no single one of them is sufliciently high to occasion brittleness, which might result, were a single hardener to be employed. For instance, by employing both 0 manganese and silicon, in addition to carbon, to secure the desired hardness, the carbon may be kept at such a small percentage as not to occasion any appreciable formation of chromecarbides.

A torsion-spring composed of my improved alloy is not only comparatively easy to form, but its tension is so nearly uniform, despite normal thermal changes, that when employed as a balanceor hair-spring in a watch or clock it insures substantially-uniform impulses to the balance-wheel oi the time-piece with which it is employed, so that all other variable factors hav- 'ing been provided for, approximately perfect Per cent Nickel 34. to 37. 50 Chromium 11. 00 to 13. 00 Manganese ,0. to 1.00 Silicon I 0. 25 to 0.90 Carbon 0. 0'7 to 0. 35

Iron forming substantially all of the balance 2. A torsion-spring combining high elastic limit, ductility and a substantially-uniform modulus of elasticity comprising the following elements within the ranges given: t

- Per cen Nickel 35. 50 to 36. 50 Chromium 11. 50 to 12; 50 Manganese 0. '70 to 0. 90 Silic 0. to 0. 80 Carbon 0. 07 to 0. 17

Iron forming substantially all of the balance THOMAS H. CHAIMBERLAIN.