Tire Mold Sector Design for Groove Accuracy
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Solution Overview
Problem
Conventional tire molds face issues with erroneous processing and uneven wear in the inclined grooves of molded tires due to partial cutting and uneven wear patterns.
Innovation Solution
A mold design featuring sectors with distinct convex portions of varying sizes and chamfered corners to prevent accidental removal and wear, ensuring accurate processing and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the projecting portion is divided into small pieces to reduce height and width, then the mold size is reduced, but the small pieces may be mistaken for burrs and erroneously removed
Solution Approach 1:
The mold is divided into multiple sectors arranged in parallel, with each sector containing portions of the projecting structure. This segmentation allows the mold to form inclined grooves while maintaining sufficient projecting portion size in each sector to prevent erroneous removal during processing.
Solution Approach 2:
The projecting portion is designed with non-uniform characteristics: the first convex portion has a larger occupied volume while the second convex portion has a smaller occupied volume but maintains sufficient length (≥1.5mm) and height to be distinguishable from burrs. This local quality variation prevents erroneous removal while achieving size reduction.
2Ease of manufacture
If the lateral groove is bent to follow the projection shape, then the mold can be formed, but uneven wear occurs in the obtained pneumatic tire
Solution Approach 1:
The projecting portion forming the lateral groove is divided between two adjacent sectors (first and second sectors). The first sector contains the first convex portion and the second sector contains the second convex portion, which together form the complete lateral groove structure. This segmentation allows proper mold formation while maintaining groove uniformity.
Solution Approach 2:
The first convex portion and second convex portion are designed asymmetrically with different occupied volumes but coordinated dimensions. The second convex portion has length ≥1.5mm and height substantially the same as the first protrusion, creating an asymmetric yet balanced structure that prevents uneven wear in the formed pneumatic tire.
3Ease of operation
If the sector end surfaces collide when the mold is closed, then the mold can be assembled, but damage occurs to the end surfaces
Solution Approach 1:
The corner of the end surface side of the first sector is chamfered, creating a curved transition rather than a sharp corner. This curvature reduces stress concentration and prevents damage to the end surfaces when sectors collide during mold closure, while still allowing proper assembly.
Data Source
AI summary
A mold for vulcanizing a tire includes a plurality of first and second sectors alternatively arranged in parallel in a circumferential direction to form an annular shape. A projecting portion formed across the first sector and the second sector includes a first convex portion whose occupied volume is larger, which is formed in the first sector, and a second convex portion whose occupied volume is smaller, which is formed in the second sector. The second convex portion has a length of at least 1.5 mm along an extending direction of the protrusions from an end surface of the second sector and has substantially the same height as the protrusions, and a corner portion of an end surface side of the first sector is chamfered.