Two-Layer Squeegee Design for Pneumatic Tyre Steel Cord Adhesion
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Solution Overview
Problem
The high cost of producing squeegee layers in pneumatic vehicle tires for heavy-duty vehicles due to the need for expensive rubber mixtures with high natural rubber content and adhesion promoters to prevent steel cords from showing through, especially when the layer thickness needs to be substantial.
Innovation Solution
A two-layer squeegee layer design where the outer layer, in contact with the carcass layer, is optimized for steel cord adhesion and durability using additives like resorcinol, cobalt salt, HMMM, and ZnO, while the inner layer, in contact with the inner tire layer, uses synthetic rubber and fewer additives to reduce costs, allowing the outer layer to be significantly thinner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick squeegee layer with high natural rubber content and adhesion promoters is used to prevent steel cords from showing through, then the effectiveness of preventing cord visibility is improved, but the production cost increases significantly
Solution Approach 1:
The squeegee layer is divided into two distinct layers: an outer adhesive layer (0.3-1.5 mm) containing natural rubber and adhesion promoters for steel cord bonding, and an inner filler layer (0.5-2.0 mm) containing mostly filler material for cost reduction. This segmentation allows each layer to perform its specific function optimally while reducing overall material costs.
Solution Approach 2:
Different regions of the squeegee layer are assigned different material compositions tailored to their specific functions. The outer layer uses expensive natural rubber (60-80 phr) and adhesion promoters (resorcinol 0.5-2.0 phr, cobalt salt 0.5-1.0 phr, HMMM 0.5-1.0 phr) for effective steel cord adhesion, while the inner layer uses mostly filler (80-95 phr) for cost reduction, creating local optimization of material properties.
2Duration of action of stationary object
If the squeegee layer thickness is increased to ensure durability and adhesion, then the adhesion and durability are improved, but the production cost increases
Solution Approach 1:
The squeegee layer is segmented into an outer adhesive layer providing durability through steel cord adhesion and an inner filler layer providing bulk thickness at lower cost. This allows achieving the required total thickness (0.8-3.5 mm) for durability while minimizing expensive material usage.
Solution Approach 2:
The patent optimizes the thickness parameters of each layer: outer adhesive layer (0.3-1.5 mm) and inner filler layer (0.5-2.0 mm), allowing flexibility in total thickness (0.8-3.5 mm) while maintaining cost-effectiveness. The parameter optimization ensures sufficient adhesion and durability without excessive material consumption.
3Strength
If high proportions of natural rubber and adhesion promoters are used in the squeegee layer, then the steel cord adhesion is improved, but the production cost increases significantly
Solution Approach 1:
The squeegee layer is segmented so that only the outer adhesive layer (0.3-1.5 mm) contains expensive natural rubber (60-80 phr) and adhesion promoters (resorcinol 0.5-2.0 phr, cobalt salt 0.5-1.0 phr, HMMM 0.5-1.0 phr), while the inner filler layer (0.5-2.0 mm) contains mostly filler (80-95 phr) and minimal rubber (5-20 phr). This segmentation concentrates adhesion-promoting materials where they are most needed for steel cord bonding.
Solution Approach 2:
The material composition varies locally across the squeegee layer thickness. The outer layer has high natural rubber content (60-80 phr) and adhesion promoters for maximum steel cord adhesion, while the inner layer has low rubber content (5-20 phr) and high filler content (80-95 phr) for cost reduction, achieving local optimization of adhesion strength.
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 design reduces production costs significantly while maintaining effective steel cord adhesion and preventing carcass cords from showing through, even with thinner outer layer thicknesses, ensuring durability and adhesion without compromising tire performance.
Implementation Method 1
ZnO as an adhesion promoter in a proportion of at least 4 phr
Implementation Method 2
The outer layer of the squeegee layer contains one or more of the additives resorcinol, cobalt salt or HMMM, each in a proportion of 0.5 phr to 3.0 phr
Data Source
Figure 1
AI summary
The tire has a carcass ply (3) extending from reinforcing members of a steel cord (5) along a radial direction. A squeegee layer is introduced between the carcass ply and an inner layer (2). The squeegee layer is constructed in two layers. The carcass ply faces an outer layer (1b) on an adhesive mixture based on durability of the steel cord. Another inner layer (1a) is formed of a rubber mixture with constituents that characterize the adhesive mixture. The outer layer is formed as an adhesion promoter.