Toothed Belt Tooth Structure for Chipping Resistance and Bendability
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Solution Overview
Problem
Existing toothed belts struggle to achieve both rigidity and bendability, leading to potential cracking and chipping under high load conditions, particularly in miniaturized applications.
Innovation Solution
A toothed belt design with a two-layer rubber structure, where the first rubber layer has a higher elastic modulus than the second layer, and incorporates oriented short fibers, enhancing both rigidity and bendability while preventing crack progression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rigidity of the tooth portion is increased to prevent deformation under high load, then the tooth chipping resistance is improved, but the bendability of the belt is deteriorated
Solution Approach 1:
The tooth portion is constructed with a non-uniform rubber layer structure where the first rubber layer has different properties than the second rubber layer. Specifically, the first rubber layer contains oriented short fibers and has higher tensile strength to resist chipping, while the second rubber layer has different composition to maintain overall belt flexibility. This local differentiation allows the tooth portion to have high rigidity where needed without compromising the bendability of the entire belt.
Solution Approach 2:
The tooth portion uses a composite rubber layer structure combining two different rubber compositions. The first rubber layer incorporates oriented short fibers (5-60 parts by mass per 100 parts rubber component) to enhance strength and chipping resistance, while the second rubber layer has a different composition that maintains flexibility. This composite structure enables simultaneous achievement of tooth rigidity and belt bendability.
2Adaptability or versatility
If a miniaturized toothed belt is used to accommodate small diameter pulleys, then the adaptability to miniaturized machines is improved, but a higher load acts on the toothed belt leading to reduced durability
Solution Approach 1:
The invention applies local quality enhancement at the tooth portion where the highest stress concentrates during meshing with small diameter pulleys. The first rubber layer with oriented short fibers and higher tensile strength (40-90 MPa) is specifically positioned at the tooth portion to withstand the intensified loads from miniaturized applications, while the rest of the belt maintains flexibility for proper engagement with small pulleys.
Solution Approach 2:
The composite rubber layer structure with two distinct rubber compositions enables the belt to simultaneously achieve the flexibility needed for miniaturized applications and the strength required to withstand higher loads. The first rubber layer provides enhanced strength for durability, while the second rubber layer maintains the overall flexibility needed for compatibility with small diameter pulleys.
3Strength
If the elastic modulus of the rubber layer is increased to prevent crack occurrence, then the tooth chipping resistance is improved, but the bendability of the toothed belt is deteriorated
Solution Approach 1:
The invention implements local quality control by creating a non-uniform rubber layer structure where the first rubber layer has higher elastic modulus and strength properties specifically at the tooth portion to resist chipping, while the second rubber layer has different properties that maintain overall belt flexibility. This allows crack prevention at critical locations without compromising global bendability.
Solution Approach 2:
The composite structure of two rubber layers with different elastic moduli and compositions enables differential mechanical properties throughout the belt cross-section. The first rubber layer with oriented short fibers provides high strength and crack resistance at the tooth portion, while the second rubber layer contributes to overall flexibility, achieving both crack prevention and bendability.
Data Source
AI summary
The present invention relates to a toothed belt, including: a back portion including a tension member; a plurality of tooth portions; a back rubber layer; and a first rubber layer and a second rubber layer that are formed on a belt inner circumferential side with respect to the tension member, in which an elastic modulus of the first rubber layer is larger than that of the second rubber layer, the first rubber layer includes a first crosslinked rubber composition including a first rubber component and a first short fiber, a proportion of the first short fiber is 5 parts by mass to 60 parts by mass with respect to 100 parts by mass of the first rubber component, the first short fiber is oriented in a belt longitudinal direction along a contour of the tooth portion.