Tire Mold Arc Profile for Wide Tread Grooves and Even Contact Pressure
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Solution Overview
Problem
Existing tire molds struggle to form wide circumferential grooves on tire treads without causing disturbances in the inner surface shape, leading to waviness in the belt and uneven ground-contact pressure distribution, which affects steering stability and wear resistance.
Innovation Solution
A tire mold design featuring a tread-forming surface with specific projections and land surface-forming portions, where the contour between projections is represented by a single circular arc, allowing controlled flow of unvulcanized rubber to prevent disturbances and achieve appropriate ground-contact surface shape and pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wide circumferential grooves (groove width ≥ 9 mm) are formed on the tread, then drainage performance and grip are improved, but disturbance occurs in the inner surface shape of the tread and the belt becomes wavy
Solution Approach 1:
The invention applies different geometric characteristics to different regions of the tread-forming surface. Specifically, the land surface-forming portions have contours represented by circular arcs convex toward the tread interior, while the projections forming the grooves have different width characteristics. This local differentiation allows the mold to control rubber flow in different areas independently, preventing disturbance in the inner surface shape while maintaining the desired groove geometry for drainage and grip performance.
2Shape
If the volume of unvulcanized rubber pressed against wide projections is increased, then wide circumferential grooves can be formed, but it becomes difficult to control the thickness of the tread
Solution Approach 1:
The invention employs circular arc contours for the land surface-forming portions of the tread-forming surface. The circular arc geometry provides smooth curvature that guides the unvulcanized rubber flow uniformly, preventing sudden changes in rubber distribution. This curved surface design allows wide circumferential grooves to be formed while maintaining consistent tread thickness control, as the circular arc profile naturally distributes the rubber volume more evenly compared to sharp or angular geometries.
3Stress or pressure
If disturbance occurs in the inner surface shape of the tread, then ground-contact pressure becomes uneven, but steering stability and wear resistance deteriorate
Solution Approach 1:
The invention changes the geometric parameters of the tread-forming surface, specifically setting the contour of land surface-forming portions to be represented by circular arcs convex toward the tread interior. This parameter change in the mold geometry directly influences the resulting tread surface shape, producing a smoother inner surface that translates to more uniform ground-contact pressure distribution. The circular arc parameter provides optimal curvature to eliminate disturbance while ensuring even pressure contact for improved steering stability and wear resistance.
Data Source
AI summary
In a tread-forming surface of a mold, a contour of a land surface-forming portion located between two projections among at least three land surface-forming portions can be represented by a single circular arc that is convex outward. In a case where, of the two projections, one projection is a wide projection and the other projection is a narrow projection, when a surface that has a contour represented by at least one circular arc and that is tangent to the at least three land surface-forming portions is defined as a reference surface of the tread-forming surface, a drop distance from the reference surface to an end on the wide projection side of the land surface-forming portion can be longer than a drop distance from the reference surface to an end on the narrow projection side of the land surface-forming portion.