Elevator Sheave Coating with Wax-Filled Microcracks
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Solution Overview
Problem
Traction-based elevator sheaves coated with known materials are prone to corrosion due to microcracks in the coatings, which reduces friction and necessitates frequent replacement, as existing coatings fail to effectively prevent corrosive substances from entering these cracks.
Innovation Solution
A hard chrome coating with microcracks filled with an inert wax filler is applied to the sheave, which infiltrates and seals the cracks, preventing corrosion and maintaining the friction relationship between the sheave and the load bearing assembly, and the filler is compatible with the polymer materials used in the load bearing assembly's jacket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard chrome coating is applied to the sheave, then wear resistance is improved, but corrosion resistance deteriorates due to microcracks in the coating
Solution Approach 1:
The patent applies a two-layer coating system where the first layer (hard chrome) provides wear resistance and the second layer (corrosion-resistant coating) provides corrosion resistance. Each layer has specialized properties tailored to its specific function, resolving the contradiction by assigning different quality characteristics to different parts of the coating system.
Solution Approach 2:
The patent uses a composite coating structure consisting of a hard chrome layer combined with a corrosion-resistant coating layer. This composite approach allows the system to simultaneously achieve both wear resistance from the hard chrome and corrosion resistance from the outer layer, eliminating the trade-off between these two properties.
2Force
If the coating is made smoother to reduce friction, then traction is improved, but corrosion protection is reduced as corrosive substances can more easily penetrate surface defects
Solution Approach 1:
The patent creates different surface characteristics in different layers: the hard chrome layer maintains appropriate roughness for traction while the outer corrosion-resistant layer provides a smooth, sealed surface that prevents corrosive substance penetration, thus resolving the contradiction between friction requirements and corrosion protection.
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 significantly reduces corrosion and wear, enhancing the lifespan of the sheave by maintaining the friction relationship and preventing corrosive substances from entering the microcracks, thus extending the operational life of the elevator system.
Implementation Method 1
The filler infiltrates microcracks in the coating to at least partially fill the microcracks
Implementation Method 2
The load bearing assembly is in a friction relationship with the coating on the sheave
Data Source
Figure 1
Figure 2~5
AI summary
An elevator sheave (28) includes a sheave body (28) and a coating (31) on a surface of the sheave body (28). The coating (31) includes microcracks (34) and a filler (33) in the microcracks (34). A method of making a sheave (28) for an elevator system is also disclosed.