Rigid Core Divided Pieces Balance Thermal Expansion
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Solution Overview
Problem
The nonuniform thermal expansion of a rigid core during vulcanization molding leads to uneven vulcanizing pressure in tire manufacturing, resulting in poor tire quality and air retention issues.
Innovation Solution
A rigid core with divided core pieces made of different metal materials, where the coefficient of thermal expansion varies radially to minimize expansion nonuniformity, using materials with higher expansion coefficients inward and lower expansion coefficients outward from the maximum width position to balance thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rigid core is used for tire forming, then tire forming accuracy is improved, but nonuniform thermal expansion occurs during vulcanization molding
Solution Approach 1:
The rigid core body is divided into multiple core pieces arranged in the radial direction, with each piece made of different metal materials having different coefficients of thermal expansion. This segmentation allows each piece to contribute differently to the overall thermal expansion behavior, enabling uniformization of the total expansion.
Solution Approach 2:
Different regions of the rigid core (radially inner and outer portions) are made of different metal materials with specifically selected coefficients of thermal expansion. The radially inner core pieces use materials with higher thermal expansion coefficients while outer pieces use materials with lower coefficients, creating local property variations that compensate for nonuniform expansion.
2Temperature
If thermal expansion occurs in the core body during vulcanization, then the core body expands radially and cross-sectionally, but nonuniform expansion causes nonuniform vulcanizing pressure
Solution Approach 1:
The coefficients of thermal expansion of different core pieces are carefully selected and adjusted to achieve uniform overall expansion. By changing the material parameters (thermal expansion coefficients) of each core piece, the patent compensates for the nonuniform expansion that would otherwise occur in a homogeneous core body during vulcanization heating.
3Productivity
If nonuniform vulcanizing pressure is applied, then tire quality deteriorates due to insufficient vulcanization on the bead side
Solution Approach 1:
The rigid core is designed with non-uniform thermal expansion characteristics built into its structure beforehand, which preemptively counteracts the tendency toward nonuniform pressure distribution during vulcanization. This preliminary design ensures that even under thermal loading, the pressure remains uniform, preventing quality issues before they occur.
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
This configuration uniformalizes vulcanizing pressure, preventing insufficient vulcanization and air retention, thereby enhancing tire quality by minimizing expansion nonuniformity and ensuring consistent pressure distribution.
Implementation Method 1
the outward divided core piece and the inward divided core piece are respectively formed of metal materials different from each other in coefficient of thermal expansion... the nonuniformity of the expansion (d) of the core body (a1)
Data Source
AI summary
A rigid core for forming a tire is configured so that the non-uniformity of the amount of thermal expansion of the core body is reduced to improve the quality of the tire. The core body comprises divided core pieces (10i , 10o) divided inward and outward in a tire radial direction at a tire radial position (P) including a maximum width position (P0) of the tire forming surface. Outward divided core pieces (10o) disposed outward in the tire radial direction than the maximum width position (P0) and inward divided core pieces (10i) disposed inward in the tire radial direction than the maximum width position (P0) are respectively formed of metal materials different from each other in coefficient of thermal expansion. The coefficient of thermal expansion of the inward divided core piece (10i) is higher than a coefficient of thermal expansion of the outward divided core piece (10o).