Bernoulli Curve Mainspring Molded Helix for Fatigue Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mechanical timepiece mainsprings experience durability degradation and fatigue failure due to plastic deformation during winding and unwinding, particularly in the helical portion, leading to reduced lifespan and increased risk of breakage.
Innovation Solution
A timepiece mainspring with a molded helical portion in a Bernoulli curve shape, fixed to the barrel arbor and engaging with the barrel's inner wall, is designed to minimize plastic deformation by setting the number of rolls between 2.5 and 3.0, using materials like nickel cobalt alloy or stainless steel to enhance durability and torque while reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the helical portion is formed by plastic deformation, then the mainspring can be manufactured, but durability is degraded and fatigue failure occurs
Solution Approach 1:
The helical shape is formed in advance during the molding process before the mainspring is assembled into the barrel. This preliminary formation of the helical portion eliminates the need for subsequent plastic deformation operations, thereby maintaining durability while achieving the required helical configuration
Solution Approach 2:
The mechanical plastic deformation process is replaced with a molding process that directly forms the helical shape. This substitution eliminates the harmful effects of plastic deformation on the material structure while still achieving the desired helical geometry for the mainspring
2Reliability
If the number of rolls of the helical portion is increased, then durability is improved, but the mainspring length increases
Solution Approach 1:
The number of rolls of the helical portion is optimized to a specific range (2.5 to 3.0 rolls) based on balancing durability requirements with spatial constraints. This parameter optimization ensures sufficient durability while preventing excessive mainspring length that would compromise the overall device compactness
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A timepiece mainspring is accommodated inside a barrel, an inner end thereof is fixed to a barrel arbor included in the barrel, and an outer end thereof engages with an inner wall of the barrel. The timepiece mainspring includes a helical portion wound in a Bernoulli curve shape from the inner end in a free state having no applied load.