Single-Layer Winch Drum for Offshore Hoisting Wear Reduction
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Solution Overview
Problem
Offshore drilling rigs face frequent wire rope failures and high operational costs due to excessive wear from multiple sheaves and bending cycles, leading to short wire rope lifetimes and safety concerns during heavy lifting operations.
Innovation Solution
A single-layer winch system with a large winch drum and reduced number of sheaves, utilizing multiple parallel wires and a high D/d ratio, along with heave compensation and electric drive means, to minimize wear and enhance safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If multiple layers of wire rope are used on the winch drum to accommodate the required length, then the wire rope can be long enough to reach the load, but the overlying layers exert great forces on underlying layers causing increased wear and reducing wire rope lifetime
Solution Approach 1:
The patent transitions from a multi-layer wire rope configuration to a single-layer configuration by increasing the winch drum diameter. This dimensional change allows the wire rope to be wound in a single layer while still achieving the required operational length, thereby eliminating the wear caused by overlying layers and extending wire rope lifetime.
2Force
If a large number of sheaves are used in the draw-works to achieve the required mechanical advantage, then the lifting force is sufficient, but the wire rope undergoes numerous bending cycles causing considerable wear and reducing wire rope lifetime
Solution Approach 1:
The patent changes the mechanical parameters of the system by increasing the winch drum diameter and reducing the number of sheaves. This parameter change maintains the required lifting force while significantly reducing the number of bending cycles the wire rope undergoes, thereby extending wire rope lifetime.
3Force
If multiple small sheaves are used in the draw-works, then the mechanical advantage is achieved, but the inertia loss in the sheaves leads to slow acceleration of the load and increased operation time
Solution Approach 1:
The patent changes the system parameters by reducing the number of sheaves and increasing the winch drum diameter. This reduces the total inertia of the moving parts, enabling faster acceleration of the load and reducing overall operation time while maintaining the required mechanical advantage.
4Device complexity
If only one wire is used in the hoisting system, then the system is simpler, but the wire is subject to severe wear and the risk of wire breakage is high causing safety concerns
Solution Approach 1:
The patent divides the single wire rope into multiple parallel wire ropes. This segmentation provides redundancy, so that if one wire rope fails, the others can still support the load, thereby improving safety and reliability while maintaining relatively simple system architecture.
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 system significantly extends wire rope lifetime, improves safety, and reduces operational downtime by reducing bending cycles and inertia loss, allowing for longer operation periods without frequent replenishment.
Implementation Method 1
the wire rope is connected to a load through a draw-works including many small sheaves over which the wire runs and is repeatedly bent. During lifting and lowering, and particularly in heave compensation, the wire rope undergoes numerous bending cycles under load, and is therefore subject to considerable wear.
Implementation Method 2
a winch drum, in a first position of use, adapted to accommodate a single layer of said elongated hoisting member, wherein a ratio between the diameter of said winch drum in the first position of use and the diameter of said elongated hoisting member is larger than 40
Data Source
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AI summary
There is described a system (1) for hoisting a load (7) on an offshore rig, the system (1) comprising - a winch (2) having a winch drum (23); - drive means (3) for operating said winch (2); - one or more sheaves (51a, 53a), - an elongated hoisting member (21, 21', 21'', 21'''), such as a wire rope, adapted to run over said one or more sheaves (51a, 53a) and to connect said winch (2) to a load (7), wherein said winch drum (23), in a first position of use (A), is adapted to accommodate a single layer of said elongated hoisting member (21, 21', 21'', 21''').