Dynamic balancing of a flexure-based Watt’s linkage horological oscillator

IF 3.5 2区 工程技术 Q2 ENGINEERING, MANUFACTURING
H. Schneegans, F. Cosandier, S. Henein
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引用次数: 0

Abstract

Mechanical watches are generally regulated by a balance and a spring constituting a harmonic oscillator. This mechanism is intrinsically force-balanced, which makes it essentially insensitive to gravity as well as to the linear accelerations of the watch. Nevertheless, this mechanism is not dynamically balanced, i.e., its motion is affected by the angular accelerations of the watch around axes parallel to the pivoting axis of the balance. This phenomenon degrades the chronometric precision of the watch when worn on the wrist. This article presents a novel dynamically-balanced oscillator mechanism dedicated to mechanical watches, which solves this issue: a 1-DOF mechanism relying on a flexure-based Watt’s linkage equipped with two balances rotating in opposite directions. The use of flexures brings additional advantages: absence of friction, no need for lubrication, increased quality factor, and monolithic design. The mechanism is presented with its Pseudo-Rigid-Body-Model and the numerical model used to predict force and dynamic-balancing residual defects: this includes sag and frequency variations under in-plane gravitational loads and pose sensitivity to in-plane angular accelerations. Experimental results from a 2:1 scale titanium prototype, compared to a watch-scale prototype, validated both the analytical and numerical models for large force and dynamic-balancing defects. An iterative tuning method achieved a sag variation below 5μm, a daily rate variation of less than 18 seconds per day for all in-plane gravity orientations, and sensitivity to angular accelerations 250 times lower than its single-balance version.
基于挠性瓦特连杆钟表振荡器的动平衡
机械表一般由摆轮和构成谐振子的弹簧来调节。这种机制本质上是力平衡的,这使得它基本上对重力和手表的线性加速度不敏感。然而,这个机构不是动态平衡的,也就是说,它的运动受到手表围绕平行于天平旋转轴的轴的角加速度的影响。这种现象会降低手表戴在手腕上时的计时精度。本文介绍了一种新型的机械表动平衡振荡机构,解决了这一问题:一自由度机构依靠基于挠度的瓦特连杆,配有两个相反方向旋转的天平。使用挠曲带来了额外的优点:没有摩擦,不需要润滑,提高质量因素,和整体设计。提出了该机构的拟刚体模型和用于预测力和动平衡残余缺陷的数值模型,其中包括平面内重力载荷下的凹陷和频率变化以及平面内角加速度下的位姿敏感性。2:1比例的钛制原型的实验结果,与手表比例的原型进行了比较,验证了大力和动平衡缺陷的分析和数值模型。迭代调谐方法实现了低于5μm的凹陷变化,对于所有平面内重力定向,每天的速率变化小于18秒,对角加速度的灵敏度比单平衡版本低250倍。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
7.40
自引率
5.60%
发文量
177
审稿时长
46 days
期刊介绍: Precision Engineering - Journal of the International Societies for Precision Engineering and Nanotechnology is devoted to the multidisciplinary study and practice of high accuracy engineering, metrology, and manufacturing. The journal takes an integrated approach to all subjects related to research, design, manufacture, performance validation, and application of high precision machines, instruments, and components, including fundamental and applied research and development in manufacturing processes, fabrication technology, and advanced measurement science. The scope includes precision-engineered systems and supporting metrology over the full range of length scales, from atom-based nanotechnology and advanced lithographic technology to large-scale systems, including optical and radio telescopes and macrometrology.
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