Watch Hand Barrel Elastic Deformation for Low Driving Force
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Solution Overview
Problem
Conventional watchmaking hands require high driving force due to the need for small slots in the barrel, which weakens the material and increases production complexity and cost.
Innovation Solution
A watch hand with a barrel featuring internal flats that elastically deform to securely attach to a cylindrical axis, reducing the required driving force while maintaining holding force, using metal alloys like copper, gold, or steel alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If slots are made in the barrel to enable elastic deformation for fixing, then the holding force is improved, but the barrel strength is weakened and manufacturing complexity increases
Solution Approach 1:
The invention applies local quality by creating a flat zone specifically at the inner diameter of the barrel where elastic deformation is needed, while keeping the rest of the barrel structure intact and strong. This localized modification allows the barrel to deform elastically for secure fixing without compromising the overall structural integrity of the barrel.
Solution Approach 2:
The invention segments the barrel's inner diameter by introducing a flat zone that separates the deformation region from the rest of the cylindrical structure. This segmentation allows the flat portion to handle the elastic deformation required for fixing while the remaining cylindrical portions maintain their full strength.
2Reliability
If narrow slots are created in the barrel for elastic deformation, then the holding force is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
Instead of creating narrow slots by removing material (subtraction), the invention inverts the approach by adding a flat zone through plastic deformation or machining that displaces material radially outward. This inversion transforms a complex slot-cutting operation into a simpler forming process that achieves the same elastic deformation effect.
Solution Approach 2:
The invention changes the geometric parameter of the barrel's inner diameter by introducing a flat zone with altered cross-sectional shape. This parameter change enables elastic deformation without requiring precise narrow slot dimensions, thereby simplifying manufacturing tolerances and reducing production complexity.
3Force
If the barrel diameter is reduced to match the axis diameter, then the driving force is reduced, but the holding force during impacts is insufficient
Solution Approach 1:
The invention applies dynamics by making the barrel's inner diameter adaptable rather than fixed. The flat zone allows the barrel to dynamically deform elastically during the pressing operation to reduce the required driving force, then maintains a secure interference fit to provide sufficient holding force during impacts. This dynamic behavior resolves the contradiction between easy installation and secure retention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in a more robust and easier-to-drive watch hand with reduced production complexity and cost, requiring lower driving force (10N-25N) while maintaining adequate holding force, even under impact.
Implementation Method 1
at least one flat on its inner diameter intended to cooperate with said cylindrical axis so as to elastically deform the barrel on either side of said at least one flat
Data Source
Figure 1
Figure 2~4
AI summary
The invention relates to an indicator hand for a timepiece comprising a body and a barrel intended to be driven onto a cylindrical pin, the barrel having an internal diameter greater than the diameter of the cylindrical pin. According to the invention, the barrel has a flat surface on the inner diameter of same intended to engage with the cylindrical pin in such a way as to elastically deform the barrel to either side of the flat surface in order to fix the hand on the cylindrical pin.