Metelli Alessandro, Soardi Giuseppe, Abeni Andrea, Attanasio Aldo
Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy.
Micromachines (Basel). 2025 Jul 29;16(8):875. doi: 10.3390/mi16080875.
The ratchet click mechanism in mechanical watch movements is a micro-component essential to prevent the unwinding of the caliber mainspring, providing secure energy storage during recharging. Despite its geometrical simplicity, the ratchet click undergoes to a complex distribution of stress, elevated strains, and cyclical mechanical deformations, affecting its long-term reliability. Despite being a crucial element in all mechanical watch movements, the non-return system appears to have been overlooked in scientific literature, with no studies available on its design, modeling, and micromachining. In this work, we introduce a novel Finite Element Method (FEM) -based design strategy for the ratchet click, systematically refining its geometry and dimensional parameters to minimize peak stress and improve durability. A mechanical simulation model was created to simulate the boundary conditions, contact interactions, and stress distributions on the part. If compared with the standard component, the optimized design exhibits a decrease in peak stress values. The mechanism was micro-machined, and it was experimentally tested to validate the numerical model outputs. The integrated digital-physical approach not only underscores the scientific contribution of coupling advanced simulation with experimental validation of complex micromechanisms but also provides a generalizable method for enhancing performance of micro-mechanical components while preserving their historical design heritage.
机械手表机芯中的棘轮棘爪机构是防止机芯主发条 unwind（此处可能是“放松”之意）的关键微部件，在重新上弦时提供可靠的能量存储。尽管其几何结构简单，但棘轮棘爪承受着复杂的应力分布、高应变和周期性机械变形，影响其长期可靠性。尽管是非返回系统是所有机械手表机芯中的关键元件，但在科学文献中似乎被忽视了，尚无关于其设计、建模和微加工的研究。在这项工作中，我们为棘轮棘爪引入了一种基于有限元方法（FEM）的新颖设计策略，系统地优化其几何形状和尺寸参数，以最小化峰值应力并提高耐用性。创建了一个机械仿真模型来模拟该部件上的边界条件、接触相互作用和应力分布。与标准部件相比，优化设计的峰值应力值有所降低。对该机构进行了微加工，并通过实验测试来验证数值模型的输出。这种集成的数字 - 物理方法不仅强调了将先进模拟与复杂微机构的实验验证相结合的科学贡献，还提供了一种通用方法，可在保留其历史设计传统的同时提高微机械部件的性能。
