Two-Component Cord for Power Transmission Belt Molding
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Solution Overview
Problem
The existing methods for molding endless power transmission belts face challenges with tensile member construction, particularly when using expanding molds or mandrels, as the tensile member must stretch and align properly within the expanding slab, leading to issues like excessive cord movement and poor alignment, especially in shorter belts where the expansion can cause damage and reduce the belt's tensile strength and fatigue life.
Innovation Solution
A two-component tensile cord is introduced, comprising a primary tensile component with suitable strength, modulus, and flexibility, and a sacrificial component with high modulus but low elongation, which is designed to fail during the molding process, minimizing stretch and maintaining the integrity of the primary component for optimal belt properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an expanding mold or mandrel is used to press belt materials radially outward, then the belt profile can be formed during molding, but the tensile member experiences excessive stretching and movement leading to poor cord alignment
Solution Approach 1:
The tensile member is segmented into two distinct components: a sacrificial component (low modulus polymer) and a functional component (high strength fiber). This segmentation allows each component to serve different purposes during molding - the sacrificial component absorbs expansion forces while the functional component maintains cord alignment and tensile strength.
Solution Approach 2:
The sacrificial component acts as an intermediary between the expanding mold and the functional tensile component. It mediates the expansion forces, protecting the functional component from excessive stretching and movement, thereby ensuring proper cord alignment in the finished belt.
2Ease of manufacture
If the tensile member is required to stretch during expansion, then the belt can be formed on expanding molds, but the tensile member may be damaged reducing belt tensile strength and fatigue life
Solution Approach 1:
The sacrificial component is designed as a disposable element that is intentionally damaged or destroyed during the molding process. It serves its purpose by absorbing expansion forces and protecting the functional tensile component, then is discarded or remains as degraded material that does not compromise the final belt strength.
Solution Approach 2:
The sacrificial component provides beforehand cushioning by absorbing and dissipating the mechanical stresses generated during mold expansion. This protective cushioning occurs before the functional tensile component is exposed to damaging forces, ensuring the belt maintains its tensile strength and fatigue life.
3Device complexity
If a single-component tensile cord is used, then the construction is simpler, but it cannot provide both the necessary stretch during processing and the required strength in the finished belt
Solution Approach 1:
The tensile member is constructed as a composite of two materials with complementary properties: a low modulus polymer providing stretch and flexibility during processing, and a high strength fiber providing tensile strength and structural integrity in the finished belt. This composite construction resolves the contradiction between simplicity and adaptability.
Data Source
Figure 1~2
Figure 3~7
Figure 8~5
AI summary
A belt having a tensile cord (12) embedded in the belt, extending in a longitudinal direction and made up of two components: a tensile component (31) and a sacrificed component (32'). The sacrificed component may be broken into a plurality of discontinuous segments (32'). The tensile component provides most of the reinforcement of the belt. The sacrificial component of the precursor cord protects the tensile component from excessive stretching during cord treating and winding, but breaks, melts, or yields during mandrel expansion during the belt molding process, thus preserving the stretchability of the tensile component.