Patent ID: 9146535
Filing Date: 2015-09-29
Classification: G04B

Abstract:
1. A timepiece barrel assembly, comprising: at least one barrel mainspring mounted between, at a first end a barrel drum, and at a second end, a receiving surface comprised in a barrel core coaxial to said drum about a pivot axis, wherein said spring is made of a multiphase, cobalt-nickel-chromium based alloy, comprising 44 to 46% cobalt, 20 to 22% nickel, 17 to 19% chromium, 4 to 6% iron, 3 to 5% tungsten, 3 to 5% molybdenum, 0 to 2% titanium, 0 to 1% beryllium, and having a Young's modulus of between 200 and 240 GPa and a shear modulus of between 80 and 100 GPa, and having a width to thickness ratio of between 9 and 21, and wherein said core is made of steel or stainless steel, and wherein the maximum radius of said core relative to said pivot axis is less than ten times the maximum thickness of said spring, and further wherein said core includes in series, from a first end towards a second end: and wherein the external diameter of said core decreases in steps from said collar towards said second end, and decreases in steps from said collar towards said first end.