Watch Part Forging and Heat Treatment for Uniform Mirror Finishing

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Solution Overview

Problem

Existing watch part manufacturing methods face limitations in achieving uniform crystal grain size and isotropic crystal orientation, leading to non-uniform polishing and reduced mirror finishing quality, which affects the luxury perception of the watch.

Innovation Solution

A method involving forging and heat treatment of metal raw materials using a die designed to control distortion within a predetermined range, followed by heat treatment conditions tailored to achieve uniform crystal grain size and isotropic crystal orientation, ensuring consistent polishing quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the metal composition is processed into a cylindrical shape by rolling, forging, or drawing, then the watch part can be manufactured, but the crystal orientation becomes anisotropic and crystal grain size becomes non-uniform, limiting mirror finishing quality

Engineering Contradiction:
Improvemanufacturing processabilityVSAvoidmirror finishing quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by performing specific heat treatment before the final polishing process. The heat treatment is conducted at a temperature of 900°C to 1100°C for 10 to 60 minutes to uniformize crystal grain size and isotropize crystal orientation before cutting and polishing, ensuring that the metallographic structure is optimized in advance for high-quality mirror finishing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies parameter changes by controlling the heat treatment temperature within a specific range (900°C to 1100°C) and time (10 to 60 minutes) to achieve the desired metallographic structure. By adjusting these parameters, the crystal grain size is uniformized and crystal orientation is isotropized, enabling high-quality mirror finishing while maintaining manufacturing processability.

Inventive Principle:
Principle #35Parameter changes

2Shape

If forging is performed to plastically form the metal composition into a case shape, then the watch part can be manufactured, but the crystal grain size becomes non-uniform and crystal orientation becomes anisotropic, affecting polishing uniformity

Engineering Contradiction:
Improvecase shape formationVSAvoidcrystal grain uniformity
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by performing heat treatment immediately after forging to uniformize crystal grain size and isotropize crystal orientation. This heat treatment step is conducted before cutting and polishing operations, ensuring that the metallographic structure is optimized in advance to achieve uniform polishing results and high mirror finishing quality.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies parameter changes by controlling the heat treatment temperature (900°C to 1100°C) and time (10 to 60 minutes) to transform the non-uniform crystal grain structure resulting from forging into a uniform and isotropic structure, thereby enabling both complex case shape formation and high-quality mirror finishing.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If cutting is performed to manufacture the watch part from the cylindrical metal composition, then the watch part can be produced, but directional characteristics arise in crystal grain shape and crystal orientation becomes anisotropic, limiting mirror finishing quality

Engineering Contradiction:
Improvewatch part productionVSAvoidcrystal orientation isotropy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by performing heat treatment before cutting operations to uniformize crystal grain size and isotropize crystal orientation. By optimizing the metallographic structure in advance through heat treatment at 900°C to 1100°C for 10 to 60 minutes, the subsequent cutting and polishing processes can proceed efficiently while achieving high mirror finishing quality without anisotropic effects.

Inventive Principle:
Principle #10Preliminary 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

The method enhances mirror finishing quality by ensuring uniform crystal grain size and isotropic crystal orientation, resulting in a higher sense of luxury for the finished watch parts.

Implementation Method 1

the heat treatment is performed under a heat treatment condition set according to the magnitude of the distortion of the processing target portion in the watch part material shaped by the forging to make a crystal grain size of the processing target portion uniform and to make a crystal orientation isotropic

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentEP4640337A1Watch part manufacturing method and watch part
Publication Date: 2025.10.29 SEIKO EPSON CORP
  • EP4640337A1 patent drawingFigure 1
  • EP4640337A1 patent drawingFigure 2
  • EP4640337A1 patent drawingFigure 3

AI summary

A watch part manufacturing method includes: preparing a metal raw material; manufacturing a watch part material including a processing target portion to be cut by performing forging and heat treatment on the metal raw material; and cutting out a watch part from the processing target portion of the watch part material by cutting, and polishing the watch part, in which in the forging, the metal raw material is shaped using a die designed such that a magnitude of distortion of the processing target portion in the watch part material falls within a predetermined range, and the heat treatment is performed under a heat treatment condition set according to the magnitude of the distortion of the processing target portion in the watch part material shaped by the forging to make a crystal grain size of the processing target portion uniform and to make a crystal orientation isotropic.