Timepiece Stator Non-Magnetic Region Without Dross Removal

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Solution Overview

Problem

In analog electronic timepieces, the formation of a non-magnetic region by chromium diffusion around the rotor accommodating hole of the stator leads to protrusions (dross) that cause contact issues with the train wheel, requiring time and cost to remove.

Innovation Solution

A stator with a magnetic plate material having a non-magnetic region formed by applying chromium and laser irradiation on the main plate surface, allowing for assembly without removing the dross, and incorporating shearing processing with fixed and movable dies to form the rotor accommodating hole.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If chromium is applied on the main plate surface and laser irradiation is performed to form a non-magnetic region, then magnetic flux saturation is improved and drive frequency is increased, but dross protrusions are generated that cause contact with the train wheel

Engineering Contradiction:

Improvedrive frequencyVSAvoidcontact between stator and train wheel

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent changes the orientation of laser irradiation from the conventional train wheel surface side to the main plate surface side. This dimensional change in the irradiation direction allows the non-magnetic region to be formed while directing the dross formation away from the train wheel interaction zone, thereby preventing contact issues while maintaining the magnetic flux saturation improvement

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Instead of treating dross removal as a necessary harmful process, the patent converts the dross formation into a beneficial outcome by orienting it toward the main plate surface. The dross remains on the stator but does not interfere with train wheel operation, thus eliminating the need for time-consuming removal processes while preserving the functional benefits of chromium diffusion

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If dross is removed to prevent contact between stator and train wheel, then contact issues are resolved, but manufacturing time and cost increase

Engineering Contradiction:

Improvecontact between stator and train wheelVSAvoidmanufacturing time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent performs preliminary action by orienting the laser irradiation from the main plate surface side before assembly, which pre-determines the dross formation location away from the train wheel contact zone. This preliminary orientation eliminates the need for subsequent dross removal operations, saving manufacturing time and cost while preventing contact issues

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If chromium diffusion is performed around the rotor accommodating hole, then non-magnetic region is formed and magnetic flux saturation is improved, but dross protrusions are generated on the laser irradiation surface

Engineering Contradiction:

Improvemagnetic flux saturationVSAvoidsurface protrusion

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The patent applies local quality by creating a non-magnetic region with specific chromium concentration around the rotor accommodating hole through controlled laser irradiation from the main plate surface side. This localized treatment achieves the required magnetic flux saturation while confining dross formation to a specific region that does not interfere with train wheel operation

Inventive Principle:

Principle #3Local quality

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

Enables efficient assembly of the stator and train wheel without dross removal, reducing manufacturing time and cost while maintaining operational stability and increasing drive frequency.

Implementation Method 1

irradiating the chromium with a laser from the main plate surface side

Methodology Applied

Scientific EffectLaser irradiation: Laser

Implementation Method 2

melt and diffuse the Cr material inside the magnetic path

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

diffuse the Cr material inside the magnetic path

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS11929640B2Stator, movement, timepiece, method for manufacturing movement and method for manufacturing stator

Publication Date: 2024.03.12 SEIKO WATCH CORP

AI summary

A stator includes a magnetic plate material that has a main plate surface that is a surface to face a main plate of a movement when assembled to the main plate and that has a rotor accommodating hole formed in a part thereof; and a non-magnetic region that is made non-magnetic by applying chromium on the main plate surface around the rotor accommodating hole and irradiating the chromium with a laser from the main plate surface side.