Pre-formed Tread Blocks for Green Tyre Curing
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Solution Overview
Problem
The production of tires for vehicles operating on weak surfaces like earth and mud, such as those used in building yards and mounted on excavators, faces challenges in creating tread patterns with large blocks and deep grooves, which require high forces during molding, leading to uneven stress distribution and potential deformations in the tire's underlying structures.
Innovation Solution
A process where the tread band is formed in two distinct operations: first, a layer of elastomeric material is applied, and then blocks are added to match the desired tread pattern, allowing for a curing process without inducing significant stress on the underlying structures, thus maintaining structural integrity and homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a tread pattern with large blocks and deep grooves is formed by forcing displacement of elastomeric material during mold closure, then the desired tread pattern is achieved, but high forces are transmitted to the bearing structure causing uneven stress distribution and deformations
Solution Approach 1:
The tread pattern blocks are pre-formed on the green tyre before curing, rather than being formed by forcing material during mold closure. This preliminary shaping avoids transmitting high forces to the bearing structure while still achieving the desired tread pattern geometry.
Solution Approach 2:
The tread band is treated as a separate component that can be pre-shaped independently. The blocks are formed as distinct elements on the green tyre surface, allowing the tread pattern to be defined without requiring high-force material displacement that would stress the underlying structure.
2Shape
If high forces are applied during mold closure to form the tread pattern, then the tread blocks and grooves are created, but inner stresses and anomalous deformations are induced in the belt layers and carcass plies
Solution Approach 1:
The tread pattern is pre-formed on the green tyre before the curing process. By shaping the blocks and grooves in advance, the subsequent mold closure occurs without the need for high forces, thereby preventing inner stresses and deformations in the underlying structures while maintaining the desired tread geometry.
3Shape
If the tread pattern is formed by forced displacement of elastomeric material during curing, then the blocks and grooves are created, but uneven stress distribution leads to irregular and premature wear
Solution Approach 1:
The tread pattern blocks are pre-formed on the green tyre before curing, eliminating the need for forced material displacement during mold closure. This approach creates uniform stress distribution throughout the tyre structure, preventing the localized high stresses that cause irregular and premature wear, thereby improving overall tyre reliability.
Data Source
Figure 1~3
Figure 2
Figure 4
AI summary
A tread band (7) of raw elastomeric material is circumferentially applied around a bearing structure (3) incorporating reinforcing cords, for forming a green tyre (2) subsequently submitted to a curing treatment. The tread band (7) is formed by: making an underlayer (18) of raw elastomeric material; making blocks (12) of raw elastomeric material; applying the blocks (12) mutually spaced apart according to a predetermined tread pattern, onto the underlayer (18). During introduction of the tyre (2) into a curing mould, the blocks (12) are put in alignment with respective forming recesses (39) before closing the mould (38), so that each block (12) is engaged in the respective forming recess (39), following closure of the mould (38).