Helicopter Blade Mandrel with Roller Assembly for Composite Spar
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Solution Overview
Problem
The challenge in manufacturing composite rotor blade spars lies in the difficulty of removing molds or mandrels due to their length and varying elliptical cross-sections, which requires materials that maintain structural strength during formation but deteriorate during curing, and existing solutions are costly due to single-use molds.
Innovation Solution
A multi-component mandrel system is used, comprising forward and rearward components connected by upper and lower components, with a roller assembly providing support and allowing for easy disassembly and reassembly, enabling the mandrel to withstand fabrication forces and be reused.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single-use foam mold is used to form the composite spar, then the mold can be easily removed after curing, but the mold cannot be reused and fabrication costs increase significantly
Solution Approach 1:
The mandrel is divided into multiple separable components including forward and rearward components connected by upper and lower components. The roller assembly is further segmented into individual rollers that can be independently removed from between the mandrel components, enabling complete disassembly for reuse while maintaining ease of removal after curing
2Ease of operation
If a foam mold is used that deteriorates during curing, then the mold can be removed from the spar cavity, but the mold lacks sufficient structural strength to maintain critical spar dimensions during formation
Solution Approach 1:
The mandrel is segmented into multiple rigid components that can be assembled to form the complete mold structure. This segmentation allows each component to be structurally strong while the overall assembly can be disassembled for reuse, resolving the contradiction between strength and removability
Solution Approach 2:
Instead of using a single-use disposable mold that deteriorates, the invention uses a recoverable multi-component mandrel system. The mandrel components are designed to be removed and reused multiple times, eliminating the need to sacrifice mold strength for ease of removal
3Shape
If a long cylindrical mold with varying elliptical cross-section and twist is used, then the complex spar shape can be formed, but the mold becomes extremely difficult to remove after the spar cures
Solution Approach 1:
The mandrel is divided into forward and rearward components connected by upper and lower components with roller assemblies. This segmentation allows the mandrel to be disassembled into manageable sections that can be easily removed from the cured spar, even when the spar has complex varying elliptical cross-sections and twists
Solution Approach 2:
The roller assembly provides a dynamic removal mechanism where rollers can be pulled out longitudinally to disconnect the upper and lower mandrel components. This dynamic disassembly process enables easy removal of the mandrel from complex spar geometries that would otherwise be extremely difficult to extract
Data Source
AI summary
Methods and apparatus are provided for making a rotor blade spar from composite material wherein a multi-component mandrel is used to form the composite spar. The mandrel is made using a number of components that are assembled and held in place using a roller assembly. The roller assembly is removed after pre-cure lay up and compaction of the composite material. Once the roller assembly is removed, the remaining mandrel components can be separated from each other and easily removed from the spar. The mandrel components, including the roller assembly, can then be re-assembled and re-used to form additional composite spars.