Tire Mold Rough Surface Profile for Crack Prevention
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Solution Overview
Problem
In cure molding of tires, existing technologies face challenges in preventing cracks on the tire outer surface while maintaining the flow property of rubber, as surface roughness that improves rubber flow can lead to adhesive failures and micro convex portions that concentrate strain and cause cracks.
Innovation Solution
A tire mold with a rough surface molding portion having a maximum height Rz of at least 4 μm and specific material ratios Rmr(c) of 3.5% to 25% for 20% and 30% of the maximum height, respectively, to secure rubber flow and prevent sharp micro convex portions from forming deep concave portions that could crack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the surface roughness of the tire molding surface is increased to improve rubber flow property, then the flow property of rubber is improved, but adhesive failure and appearance faults are generated
Solution Approach 1:
The invention changes the surface roughness parameters by controlling the maximum height Rz within 3-15 μm and the material ratio Rmr(c) within specific ranges. This parameter optimization allows the surface to be rough enough to prevent adhesion and improve rubber flow, while not being excessively rough to cause appearance faults or adhesive failure.
2Reliability
If the surface roughness is increased to prevent adhesion, then adhesive failure is reduced, but micro convex portions form deep micro concave portions that concentrate strain and cause cracks
Solution Approach 1:
The invention controls the material ratio Rmr(c) within specific ranges (3-20% for c=Rz20%, 10-30% for c=Rz30%) to regulate the distribution and sharpness of micro convex portions. This prevents the formation of excessively sharp micro convex portions that would create deep micro concave portions and strain concentration points, thereby preventing cracks while maintaining adhesive strength.
Solution Approach 2:
The invention applies a moderate level of surface roughness rather than excessive roughness. By controlling Rz within 3-15 μm and Rmr(c) within specific ranges, the surface is made sufficiently rough to prevent adhesion and improve rubber flow, but not excessively rough to cause harmful strain concentration and cracks.
3Strength
If the surface roughness is decreased to prevent cracks, then crack resistance is improved, but rubber flow property deteriorates and adhesive failure is generated
Solution Approach 1:
The invention optimizes the surface roughness parameters by setting Rz within 3-15 μm and Rmr(c) within specific ranges. This ensures the surface is rough enough to maintain good rubber flow property and prevent adhesion, while the controlled material ratio prevents excessive sharpness that would cause cracks.
Data Source
AI summary
A tire mold has a tire molding surface and a rough surface molding portion provided in the tire molding surface. In the rough surface molding portion, a maximum height Rz is not less than 4 μm, a material ratio Rmr(c) in a case where 20% of the maximum height Rz is set to a cutting level c is not less than 3.5%, and a material ratio Rmr(c) in a case where 30% of the maximum height Rz is set to the cutting level c is not more than 25%.