Wind Turbine Blade Root Repair Using Radial Pin Reinforcement
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Solution Overview
Problem
Wind turbine blades with reinforcement rings in the root develop cracks due to machining defects and stress, leading to potential breakage and requiring frequent replacement.
Innovation Solution
The method involves creating radial bore holes in the ring, grinding and extending threaded axial blind holes to eliminate threads, and inserting pins with diametrical passages to anchor the blade to the hub, preventing crack propagation and enhancing attachment robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If threaded axial blind holes are made in the reinforcement ring for bolt attachment, then the blade can be anchored to the hub, but machining defects in these holes cause cracks to develop and propagate
Solution Approach 1:
The attachment system is divided into three separate components: the reinforcement ring, the pin inserted into radial bore holes, and the bolt passing through the pin. This segmentation isolates the stress concentration points from the critical threaded holes in the ring, preventing crack initiation while maintaining attachment functionality
Solution Approach 2:
The pin acts as an intermediary element between the reinforcement ring and the bolt. It transfers the load from the bolt to the ring through radial bore holes that are positioned away from the threaded hole locations, thereby preventing direct stress concentration at the vulnerable threaded areas
2Reliability
If the blade is replaced when cracks exceed critical length, then safety is ensured, but production loss and cost increase
Solution Approach 1:
Instead of discarding the entire blade when cracks are detected, the invention recovers the reinforcement ring by removing and replacing only the cracked pins. This selective replacement extends blade life while maintaining safety, reducing production loss and cost
3Strength
If hollow sleeves are used in axial holes to support preload, then attachment robustness improves, but the reinforcement ring cannot be compressed to prevent crack propagation
Solution Approach 1:
Instead of placing the load-bearing element (hollow sleeve) inside the axial hole as in prior art, the invention inverts the approach by using a pin that extends radially from the ring and is loaded through the bolt. This allows the ring to be compressed axially while the pin handles the preload, combining both benefits
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
Method and equipment for repairing the roots of wind turbine blades, which procedure comprises: a) Drilling on the root of the blade, and through the ring (1) thereof, radial bore holes (5) located in positions that radially match the axial threaded blind holes (2) of the ring; b) Grinding and drilling the axial threaded blind holes (2) to remove the thread, and to achieve the extension of said ground axial holes until they reach the matching radial bore hole (5); c) Introducing, into each radial bore hole (5), a pin (7) provided with a threaded diametral passage (8) aligned with a threaded axial hole (2) of the ring; d) Screwing bolts (3') into the axial threaded blind holes (2) and threaded diametral passages (8), for fastening the blade to the hub of the wind turbine. The equipment comprises a support (9) that can be fastened to the reinforcement ring (1) and a head (10) for carrying radial (13) and axial (14) drilling tools.