Elevator Rope Multi-Layer Strand Design for Sheave Wear Reduction
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Solution Overview
Problem
Conventional elevator ropes wear out quickly due to high contact surface pressure with sheaves, leading to a shortened service life and increased elevator apparatus size, and enhancing strength results in premature sheave wear.
Innovation Solution
A rope design with a core strand, six inner layer strands, and twelve outer layer strands, all formed from twisted elemental wires, with a resin covering to distribute stress uniformly and reduce bending stress, allowing for a smaller sheave diameter and extended rope life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of side strands is reduced to six, then the rope structure is simplified, but the contact area with sheave becomes small and contact surface pressure becomes large, causing early wear
Solution Approach 1:
The rope is divided into multiple functional layers: a core strand, six inner layer strands, and twelve outer layer strands. This segmentation allows the rope to have both structural simplicity and sufficient contact area, as the outer layer strands specifically contact the sheave while inner layers provide structural support.
Solution Approach 2:
The patent introduces an additional dimensional arrangement by organizing strands in concentric circles around the core. The six inner layer strands are arranged in one circle and twelve outer layer strands in another outer circle, creating a multi-dimensional structure that increases contact area without significantly increasing radial thickness.
2Reliability
If the sheave diameter is increased to increase rope life span, then the rope wear is reduced, but the elevator apparatus size increases
Solution Approach 1:
By segmenting the rope into multiple strands with different functions, the patent allows the sheave diameter to be kept small while the rope itself provides sufficient contact area through its multi-layer structure. The outer layer strands are specifically designed to contact the sheave, distributing the load across multiple contact points.
Solution Approach 2:
The patent applies local quality by giving different strands different functions: inner layer strands provide structural support while outer layer strands are optimized for sheave contact. This allows the rope to have sufficient contact area at the critical interface without requiring a larger sheave.
3Reliability
If the rope strength is enhanced to increase life span, then the rope durability improves, but the hardness of elemental wires increases causing premature sheave wear
Solution Approach 1:
The patent applies local quality by giving different strands different functions: inner layer strands provide structural support while outer layer strands are optimized for sheave contact. This allows the rope to have sufficient contact area at the critical interface without requiring a larger sheave.
Solution Approach 2:
The rope uses a composite structure combining multiple materials with different properties: steel elemental wires for strength, resin covering members for protection and stress distribution, and lubricant for reducing friction. This composite approach allows optimization of both rope strength and sheave protection.
4Strength
If elemental wires are made thicker to increase rope strength, then the rope strength improves, but bending stress becomes too large
Solution Approach 1:
The rope is divided into multiple functional layers: a core strand, six inner layer strands, and twelve outer layer strands. This segmentation allows the rope to have both structural simplicity and sufficient contact area, as the outer layer strands specifically contact the sheave while inner layers provide structural support.
Solution Approach 2:
The patent changes the parameter of strand arrangement by organizing strands in concentric circles around the core, with different numbers of strands in different layers. This arrangement optimizes the balance between rope strength and bending stress by distributing the load across multiple contact points.
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 design ensures a longer elevator rope life, reduces the overall elevator apparatus size, and prevents premature wear by distributing stress evenly and increasing the contact area with the sheave, while maintaining adequate strength.
Implementation Method 1
an inner layer covering member with which an outer periphery of the core strand is covered... and an outer layer covering member with which the core strand, the inner layer covering member and the individual inner layer strands are covered in a collective manner
Implementation Method 2
Both the core strand and the core rope strands have a resin coating body, in which the strands are embedded
Implementation Method 3
a core strand which is formed of a plurality of elemental wires twisted together... six inner layer strands which are arranged on an outer peripheral portion of the inner layer covering member at intervals from one another and are formed of a plurality of elemental wires twisted together
Implementation Method 4
a plurality of ropes are wrapped around a sheave... the contact surface pressure of each rope becomes large
Data Source
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AI summary
An elevator rope has a core rope, and twelve outer layer strands that are arranged on an outer peripheral portion of the core rope at intervals from one another. The core rope has a core strand, an inner layer covering member with which an outer periphery of the core strand is covered, six inner layer strands which are arranged on an outer peripheral portion of the inner layer covering member at intervals from one another, and an outer layer covering member with which the core strand, the inner layer covering member and the individual inner layer strands are collectively covered. The core strand, the individual inner layer strands and the individual outer layer strands are respectively composed of a plurality of elemental wires twisted together.