Tire Vulcanization Mold Surface Roughness and Laser Cleaning

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Solution Overview

Problem

The existing tire vulcanization molds face issues with rubber chip formation due to contaminants adhering to the molding surface, leading to poor tire quality and performance, particularly when using laser beam cleaning methods which can create ultrafine protrusions that cause the vulcanized rubber to remain adhered to the mold.

Innovation Solution

A tire vulcanization mold with a tread molding surface featuring a groove molding portion with a surface roughness of 0.12 µm or less and a land portion molding portion with a surface roughness of 3.2 µm or more, minimizing the adherence of vulcanized rubber and preventing rubber chip formation, while also ensuring good tire performance and avoiding excessive smoothness that could affect ice running performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the molding surface is cleaned by shot blasting method, then contaminants are removed, but the molding surface is easily damaged

Engineering Contradiction:
Improvemolding surface integrityVSAvoidsurface damage
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical shot blasting cleaning method with a laser beam cleaning method. The laser beam removes contaminants through optical energy and shock waves rather than mechanical impact, eliminating surface damage while effectively cleaning the molding surface.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the cleaning mechanism from mechanical (shot blasting) to optical/thermal (laser beam). By altering the fundamental parameter of the cleaning method from mechanical force to laser energy, the patent achieves contamination removal without surface damage.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the molding surface is cleaned by plasma cleaning method, then contaminants are chemically reacted and removed, but the cleaning area per unit time is small and maintenance is time-consuming

Engineering Contradiction:
Improvecontaminant removal effectivenessVSAvoidcleaning efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the plasma cleaning method with a laser beam cleaning method. The laser beam provides faster cleaning speed and larger coverage area per unit time, improving productivity while maintaining effective contaminant removal through optical energy and shock wave mechanisms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the cleaning method from plasma-based chemical reaction to laser-based optical energy and shock waves. This parameter change results in significantly improved cleaning efficiency and reduced maintenance time while achieving the same contaminant removal effectiveness.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the molding surface is irradiated with laser beam for cleaning, then contaminants are removed efficiently, but ultrafine protrusions are generated causing vulcanized rubber to remain adhered to the mold

Engineering Contradiction:
Improvecleaning efficiencyVSAvoidultrafine protrusion formation
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent applies different surface roughness characteristics to different regions of the molding surface. The groove molding portion has Ra ≤ 0.12 μm to prevent rubber adhesion, while the land portion molding portion has Ra ≥ 3.2 μm to maintain tire performance. This local differentiation resolves the contradiction between cleaning efficiency and protrusion-induced adhesion.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the surface roughness parameter of the groove molding portion to Ra ≤ 0.12 μm, which is significantly smoother than conventional surfaces. This parameter change prevents the formation and adhesion effects of ultrafine protrusions while maintaining the benefits of laser beam cleaning efficiency.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If the groove molding portion has high surface roughness, then ice running performance is maintained, but rubber chip formation occurs due to excessive adhesion

Engineering Contradiction:
Improveice running performanceVSAvoidrubber chip formation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies different surface roughness values to different functional regions: the groove molding portion (Ra ≤ 0.12 μm) minimizes rubber adhesion to prevent chip formation, while the land portion molding portion (Ra ≥ 3.2 μm) maintains ice running performance. This local quality differentiation resolves the contradiction between these two opposing requirements.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the molding surface into functionally distinct regions with different roughness characteristics. By dividing the surface into groove portions (for adhesion prevention) and land portions (for performance maintenance), the patent simultaneously achieves both objectives without compromise.

Inventive Principle:
Principle #1Segmentation

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 solution effectively prevents rubber chip formation by minimizing surface roughness in the groove molding portion and maintaining sufficient roughness in the land portion, facilitating easy release of the vulcanized rubber and maintaining tire performance, including ice running performance, over a long period.

Implementation Method 1

a laser beam cleaning method in which the molding surface is irradiated with a laser beam to remove the contaminants by a shock wave

Methodology Applied
Scientific EffectLaser beam: Laser

Implementation Method 2

a laser beam cleaning method in which the molding surface is irradiated with a laser beam to remove the contaminants by a shock wave

Methodology Applied
Scientific EffectShock wave: Shock Wave

Implementation Method 3

a plasma cleaning method in which the contaminants are chemically reacted and removed by generated plasma

Methodology Applied
Scientific EffectPlasma: Plasma

Data Source

PatentEP3995303B1Tire vulcanization mold and manufacturing method for tire
Publication Date: 2024.08.07 THE YOKOHAMA RUBBER CO LTD
  • EP3995303B1 patent drawingFigure 1
  • EP3995303B1 patent drawingFigure 2
  • EP3995303B1 patent drawingFigure 3~4

AI summary

A tire vulcanization mold and a method of manufacturing a tire using the mold that can ensure good tire performance while avoiding a problem of rubber chip formation in the tire over a long period of time are provided. A tire vulcanization mold (1) in which a surface roughness (Ra) in the groove molding portion (4) of the tread molding surface (3) is made smaller than a surface roughness (Ra) in the land portion molding portion (5), in which a surface roughness (Ra) in the groove molding portion (4) is minimized to 0.12 µm or less in a range including at least a main groove molding portion (4a), and in which a surface roughness (Ra) in the land portion molding portion (5) is made to be 3.2 µm or more, is used to manufacture a green tire (TG), and when cleaning the tread molding surface (3), the tread molding surface (3) is irradiated with a laser beam (L) to remove contaminant (X) adhered to the tread molding surface (3).