Ceramic Shaft for Timepiece Wheel Set Injection Molding

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Solution Overview

Problem

Manufacturing small timepiece components, such as wheel sets, is challenging due to high machining costs and difficulties in producing components with large cross-sectional differences, requiring precise geometry and shock resistance to maintain constant oscillation frequency.

Innovation Solution

A timepiece component with a shaft-like portion made of ceramic material, featuring a pivot axis and recesses for injection points, allowing for precise injection moulding and minimizing machining needs, ensuring perfect geometry and shock resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional steel arbors are used for timepiece wheel sets, then the components can be manufactured with conventional machining methods, but the machining costs are high and producing components with large cross-sectional differences is difficult

Engineering Contradiction:

Improveease of manufactureVSAvoidmanufacturing precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter from traditional steel to ceramic material, which fundamentally alters the manufacturing approach. This material substitution enables the use of injection molding instead of conventional machining, thereby reducing machining costs while achieving the required manufacturing precision for complex geometries with large cross-sectional differences

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical machining system with an injection molding process. By injecting ceramic material into a mold, the complex geometries of timepiece wheel sets are formed directly, eliminating the need for expensive and time-consuming conventional machining operations while maintaining high manufacturing precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If conventional machining methods are used for small pivot diameters, then the components can be produced, but the machining costs increase and geometric precision becomes difficult to maintain

Engineering Contradiction:

Improvegeometric precisionVSAvoidmachining cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by forming the precise geometry of the shaft-like portion and its features (including small pivot diameters) directly during the injection molding process. The mold itself is designed with the precise geometry required, so the component is formed with the correct shape before any finishing operations, eliminating the need for expensive precision machining of small features

Inventive Principle:

Principle #10Preliminary action

3Reliability

If traditional materials are used for balance staffs, then the components can be manufactured with existing processes, but the resistance to shocks is insufficient and unbalance may occur

Engineering Contradiction:

Improveshock resistanceVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs ceramic material (such as zirconium oxide or aluminum oxide) which provides superior shock resistance compared to traditional steel materials. The ceramic material's inherent properties give it higher hardness and better resistance to deformation under shock loads, thereby improving reliability while the injection molding process keeps manufacturing relatively simple

Inventive Principle:

Principle #40Composite materials

4Shape

If large cross-sectional differences are present in timepiece components, then the geometry can be achieved, but the machining difficulty and cost increase significantly

Engineering Contradiction:

Improvegeometry complexityVSAvoidmachining difficulty

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical machining with injection molding to manufacture components with large cross-sectional differences. The mold cavity is designed to accommodate the complex geometry, allowing the ceramic material to be injected and form the complete shape in one process, thereby eliminating the difficulty and high cost associated with machining such complex geometries

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11500333B2Timepiece component with a non-magnetic shaft-like portion made of ceramic

Publication Date: 2022.11.15 BLANCPAIN SA

AI summary

A timepiece component including a shaft-like portion including at least one pivot about a pivot axis, wherein at least the constituent material of this shaft-like portion is a ceramic or similar non-magnetic type material, the shaft-like portion includes a plurality of recesses evenly arranged or regularly distributed about the pivot axis, and has its centre of inertia on the pivot axis, and the shaft-like portion includes a collar forming its largest diameter with respect to the pivot axis, which collar includes a parting line of the shaft-like portion, which parting line is substantially perpendicular to the pivot axis, the recesses pass right through the collar, and at least one recess contains an injection point for the material.