Variable Diameter Roller Press for Timepiece Mainspring Formation
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Solution Overview
Problem
The complex process of press-rolling timepiece mainsprings requires perfect reproducibility and handling of springs that are awkward to manage post-rolling, often involving expensive voluminous tools and unnecessary ring shaping, leading to coil tangling and handling issues.
Innovation Solution
A gradual or variable press-rolling technique using a roller press with three-point bending to exceed the elastic limit of the strip, allowing for a constant or variable coil space and facilitating flat handling, eliminating the need for ring shaping and reducing coil tangling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional press-rolling with constant diameter is used, then the spring forms a stack of coils, but the coils cannot resume their flat shape and become awkward to handle
Solution Approach 1:
The press-rolling device employs variable diameter rollers that can be adjusted during the rolling process. The rollers transition from a smaller diameter at the start to a larger diameter toward the end, creating a progressive bending effect that allows the spring to maintain a flat configuration while being processed, thereby improving handling ease without compromising the required coil shape
Solution Approach 2:
The invention changes the geometric parameter of the rolling surface by using rollers with varying diameters along their length. This parameter change enables the spring strip to be bent into the desired spiral shape while maintaining control over the final configuration, allowing the spring to remain flat and manageable during handling operations
2Shape
If voluminous tools and ring shaping operations are used, then the spring can be formed, but the process becomes complex and expensive
Solution Approach 1:
The invention extracts and eliminates the unnecessary intermediate ring shaping operation from the conventional process. By using variable diameter press-rolling, the spring is formed directly in its final spiral configuration without requiring subsequent ring shaping and removal operations, thereby simplifying the overall process and reducing equipment complexity while maintaining the required spring shape
Solution Approach 2:
The variable diameter press-rolling performs the final spring configuration shaping as a preliminary action during the initial forming process. The progressive bending action of the variable diameter rollers pre-forms the spring in its final spiral shape, eliminating the need for subsequent ring shaping operations and reducing overall process complexity
3Ease of manufacture
If constant diameter press-rolling is used, then the process is simple, but the coils form a stack that tangles and interlaces
Solution Approach 1:
The variable diameter rollers introduce a dynamic element to the press-rolling process, where the rolling surface diameter changes progressively during formation. This dynamic approach creates a controlled spiral configuration that prevents coils from stacking and tangling, while the process remains relatively simple and integrated into the basic press-rolling operation
Solution Approach 2:
The invention applies varying curvature through rollers with different diameters along their length. The progressive change in curvature radius creates a controlled spiral path for the spring strip, preventing the sharp bends and stack formation that lead to tangling and interlacing, while maintaining process simplicity through the continuous rolling action
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
This method enables efficient handling and storage of springs in a flat configuration, reducing tangling, scratches, and interlacing, while ensuring reproducibility and ease of subsequent manufacturing operations.
Implementation Method 1
The press-rolling process consists in forcing the strip spring between two rollers and a motorized shaft to create a three-point bending of the strip, making plastic deformation thereof possible
Implementation Method 2
The principle of the invention also consists in forcing the strip between three points to exceed the elastic limit locally in the strip and thus to form the press-rolled portion
Data Source
AI summary
Method for press-rolling a mainspring, from a wire comprising a pre-formed eye, utilizing a roller press comprising a first support and guide means exerting a force on the wire in a first contact area located between a second and a third contact area comprised in a second and a third support and guide means, in order to wind, beyond the eye, an accumulation area with an opposite curvature to that of the eye, and wherein, as the wire advances, the position of the first contact area is gradually moved away from the second and third contact areas, to vary the press-rolling radius from a first minimum value to a second maximum value at a neck junction between the accumulation area and the eye.