Helical Reinforcement Strand Layout for Core Migration Resistance
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Solution Overview
Problem
Reinforcement strands in belts face core migration issues due to repetitive tension and compression cycles, leading to core wicking out of the cord and entanglement with pulleys, which results in belt failure.
Innovation Solution
A reinforcement strand design featuring a core with steel filaments twisted in a helical shape, organized in an intermediate and outer layer with specific lay lengths and diameters to prevent core migration, ensuring adequate gap formation and maintaining coherence under compression, while also enhancing adhesion to the polymer jacket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-strand cords with twisted steel filaments are used for reinforcement, then the belt has good elongation properties, jacket anchoring, low creep, and excellent fatigue life, but the modulus is somewhat low
Solution Approach 1:
The reinforcement strand is segmented into multiple layers: a core layer with steel filaments arranged in a specific pattern, an intermediate layer with steel filaments, and an outer layer with steel filaments. This layered segmentation allows each layer to contribute differently to the overall performance, with the core providing structural stability and the outer layers providing strength and modulus.
Solution Approach 2:
The invention uses a composite structure combining steel filaments with a polymer core. The steel filaments provide high modulus and strength, while the polymer core provides flexibility and prevents core migration. This composite approach resolves the contradiction between high modulus requirements and flexibility needs.
2Strength
If the core diameter and filament diameters are reduced to improve strength-to-diameter ratio, then the belt becomes more flexible and has higher strength density, but the core may migrate out of the cord under repeated load cycles
Solution Approach 1:
The core steel filaments are nested within the intermediate and outer layers of steel filaments. This nested structure prevents the core from migrating out of the cord during repeated load cycles, as the outer layers act as containment barriers. The core remains securely positioned while still allowing the strand to achieve high strength-to-diameter ratio.
Solution Approach 2:
The invention specifies precise parameter relationships: the final lay length is between 2 and 6 times the closing lay length, and the number of filaments in each layer is carefully controlled. These parameter changes ensure that the strand maintains its structural integrity under repeated loading while achieving optimal strength-to-diameter ratio.
3Strength
If the final lay length is shortened to increase the number of filaments per unit length, then the strand has higher density and strength, but the core migration problem worsens due to increased peristaltic action
Solution Approach 1:
The invention applies preliminary anti-action by designing the intermediate and outer layers to counteract the peristaltic motion that causes core migration. The specific arrangement and number of filaments in these layers create a stabilizing effect that prevents core movement before migration can occur, even when the final lay length is shortened to increase density.
4Reliability
If steel filaments are twisted tightly to prevent core migration, then core stability improves, but the strand becomes less flexible and harder to manufacture
Solution Approach 1:
The invention uses dynamic twisting where the lay length varies between layers. The intermediate and outer layers are twisted at different rates relative to the core, creating a dynamic structure that is stable under load but flexible during manufacturing and installation. This dynamic approach allows the strand to maintain core stability while remaining easy to manufacture.
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
The solution effectively prevents core migration, maintains strand coherence, and enhances adhesion to the polymer jacket, resulting in improved fatigue life and strength-to-diameter ratio, reducing the likelihood of belt failure.
Implementation Method 1
steel filaments that are twisted around said core
Data Source
AI summary
A reinforcement strand (400) comprises a core (403) around which steel filaments (404) are twisted all with the same final lay length and direction. The steel filaments are arranged in an intermediate layer comprising N first steel filaments and an outer layer of 2N steel filaments circumferentially arranged around the intermediate layer. In the intermediate layer filaments will contact one another at a closing lay length that is determined by the number of steel filaments N in the intermediate layer, the diameter of the core and the diameter of the first steel filaments. By choosing the final lay length and direction equal to the between two and six times the closing lay length gaps will form between the intermediate layer filaments. The 2N outer layer filaments are further divided into a group of smaller (408) and a group of larger (406) diameter steel filaments.