Fleet-Angle Tolerant Sheave Groove for Reliable Wire Rope Feeding
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Solution Overview
Problem
In material handling systems, particularly in block and tackle arrangements, high fleet angles between the wire rope and the sheave cause the rope to hang up and slip, leading to premature wear and failure, especially when the travelling block is pulled out from below the crown block, resulting in intermittent slippage and increased maintenance costs.
Innovation Solution
The sheave design features a uniquely shaped groove that accommodates high fleet angles, with a circular rope engaging portion and a groove profile that maintains the rope in constant tension, reducing wear by preventing hang-ups and ensuring smooth operation, while complying with API 8A and 8C specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the travelling block is pulled horizontally out from below the crown block, then the wire rope can reach the well center for pipe lifting operations, but a fleet angle is created causing the rope to hang up on the sheave rim and slip intermittently
Solution Approach 1:
The groove is designed with different local geometries: a first portion with a first radius of curvature and a second portion with a second radius of curvature. This local variation in groove quality allows the groove to accommodate the fleet angle while maintaining reliable rope engagement, resolving the contradiction between horizontal pulling capability and continuous rope feeding.
Solution Approach 2:
The groove geometry is designed to dynamically adapt to the rope's path when a fleet angle is present. The varying radii of curvature allow the groove to guide the rope smoothly through the angled entry, transforming the static groove into a dynamic solution that maintains reliability under varying operational conditions.
2Device complexity
If a conventional groove design is used, then the sheave structure is simple, but the wire rope experiences wear and premature failure due to hang-ups and slippage
Solution Approach 1:
By implementing different radii of curvature in different portions of the groove, the design locally optimizes the groove geometry to prevent rope hang-ups and slippage. This local quality variation increases wire rope lifespan while maintaining reasonable overall device complexity.
Solution Approach 2:
The groove utilizes curved surfaces with specific radii of curvature to match the rope's natural path. The first and second portions of the groove have different curvatures that collectively guide the rope smoothly, reducing wear and extending wire rope lifespan without excessive complexity.
3Ease of manufacture
If the groove does not accommodate high fleet angles, then the sheave groove is simple to manufacture, but the rope intermittently slips into the groove causing wear and premature failure
Solution Approach 1:
The groove is manufactured with locally differentiated geometry (different radii in different portions) that accommodates fleet angles while remaining practical to manufacture. This local quality approach prevents rope slippage and maintains reliability without excessive manufacturing complexity.
Solution Approach 2:
The groove design changes geometric parameters (radii of curvature) along its length to accommodate fleet angles. By varying the radius parameter from the first portion to the second portion, the groove reliably guides the rope through angled entry while remaining manufacturable.
Data Source
Figure 1
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Figure 4
AI summary
A sheave (112) including a body portion (114) with a circular circumference and defining a center plane (122), a bore (120) extending through the body portion (114) and configured for receiving a shaft and allowing the body portion (114) to rotate in the center plane (122), and a rope groove (132) arranged on the circular circumference including a radiused bottom (134) with a first end (140) and a second end (140) and a pair of opposing sidewalls (136) each extending directly and tangentially from one of the first and second end (140) and having a curved profile.