Carbon-Cord Toothed Belt Hardness Layout Against Tooth Skipping
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Solution Overview
Problem
Toothed belts made from thermoplastic elastomer compositions are prone to tooth deformation and chipping under load, leading to tooth skipping, and also suffer from early cracking of the back surface.
Innovation Solution
A toothed belt design utilizing a polyamide-based or polyester-based thermoplastic elastomer composition for both back rubber and tooth rubber portions, with a cord containing carbon filaments embedded in a spiral configuration, and a reinforcement fabric covering the tooth rubber portions to manage hardness and prevent deformation and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the hardness of the thermoplastic elastomer composition is increased to suppress deformation of the belt teeth, then the resistance to tooth deformation is improved, but cracks occur early in the back surface of the belt
Solution Approach 1:
The patent applies different hardness values to different parts of the belt: the tooth rubber portions use a harder thermoplastic elastomer composition (higher hardness) to resist deformation, while the back rubber portion uses a softer composition (lower hardness) to prevent cracking. This local differentiation of material properties resolves the contradiction between tooth strength and back surface durability.
Solution Approach 2:
The patent uses composite material structures with cords embedded in the rubber portions. The cord-reinforced composite structure provides additional strength to the back surface, preventing cracks while allowing the tooth portions to maintain their hardness for deformation resistance.
2Productivity
If a thermoplastic elastomer composition is used to form the back rubber portion and tooth rubber portions, then productivity is improved by eliminating vulcanization steps, but the belt teeth are prone to deformation and chipping under load
Solution Approach 1:
The patent changes the material parameters by selecting specific thermoplastic elastomer compositions with appropriate hardness values and molecular structures that provide both processability (for high productivity) and mechanical strength (to prevent deformation). The composition parameters are optimized to balance manufacturing efficiency with performance.
Data Source
AI summary
A toothed belt includes: a belt body having a flat band-shaped back rubber portion and tooth rubber portions placed on an inner circumferential side of the back rubber portion, the back rubber portion and the tooth rubber portions being each composed of a thermoplastic elastomer composition; a cord containing carbon filaments; and a tooth portion covering material provided on an inner circumferential side of the belt body and covering the tooth rubber portions. An elastomer component of the thermoplastic elastomer composition is a TPAE or a TPC, a hardness of the thermoplastic elastomer composition forming the back rubber portion is not less than 25 and not greater than 70, a hardness of the thermoplastic elastomer composition forming the tooth rubber portions is not less than 40 and not greater than 70, and the hardness of the thermoplastic elastomer composition forming the back rubber portion is not greater than the hardness of the thermoplastic elastomer composition forming the tooth rubber portions.