Rotatable Tread Mold Parts for Low-Resistance Tire Release

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Solution Overview

Problem

Conventional tire molds experience high undercut resistance due to projections on the tread design surface, leading to defects such as permanent deformation and projection failure during mold release, especially in tires with complex patterns.

Innovation Solution

The mold is designed with segments that include rotatable design surface dividing mold parts supported by a shaft, allowing them to rotate around the axis when the mold opens, reducing undercut resistance by facilitating the release of the tire from the projections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If projections such as ribs or blades are provided on the tread design surface to form a tread pattern with recesses and protrusions, then the tread pattern is formed successfully, but high undercut resistance is caused during mold releasing

Engineering Contradiction:
Improvetread pattern formationVSAvoidmold releasing
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The tread molding part is divided into a plurality of segments arranged in the circumferential direction. Each segment can rotate independently around a rotatable shaft, allowing the projections to be segmented and move separately during mold releasing, thereby reducing undercut resistance while maintaining tread pattern formation capability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The design surface dividing mold parts are configured to rotate around a rotatable shaft parallel to the axis of the tread molding part when the mold is opened. This dynamic rotation allows the projections to change their orientation from a fixed position to a rotated position, reducing undercut resistance during mold releasing while maintaining the ability to form complex tread patterns

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the tread design surface is provided with projections to form complex tread patterns, then the tread pattern complexity is increased, but permanent deformation and projection failure occur due to excessively high undercut resistance

Engineering Contradiction:
Improvetread pattern complexityVSAvoidprojection integrity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The rotatable design surface dividing mold parts allow the projections to dynamically adjust their position during mold opening. This rotation reduces undercut resistance, preventing projection failure and permanent deformation, thereby enabling the formation of complex tread patterns with high reliability

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By dividing the tread molding part into multiple rotatable segments, each with its own projections, the system can handle complex tread patterns while reducing the overall undercut resistance through distributed, independent rotation of each segment

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4360843B1Tire molding die and tire production method
Publication Date: 2025.12.31 BRIDGESTONE CORP
  • EP4360843B1 patent drawingFigure 1
  • EP4360843B1 patent drawingFigure 2
  • EP4360843B1 patent drawingFigure 3

AI summary

Provided are a mold for forming a tire (1) including an annular tread molding part (20) which is configured to be opened and closed by moving a plurality of segments (21) in a radial direction, and a tire production method using the same. In the mold for forming the tire (1), each of the segments (21) includes a plurality of design surface dividing mold parts (23, 24), each of the plurality of the design surface dividing mold parts (23, 24) includes a tread design surface (20c) for forming a tread (2c) of a tire (2), the plurality of the design surface dividing mold parts (23, 24) are arranged in a circumferential direction of the segments (21), and the plurality of the design surface dividing mold parts (23, 24) are configured to rotate around a rotatable shaft (26) parallel to an axis of the tread molding part (20) when the tread molding part (20) is opened after vulcanization molding of the tire (2).