Composite Moulding Assembly With Uniform Cavity Overpressure
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Solution Overview
Problem
Existing resin infusion techniques for manufacturing wind turbine rotor blades in a closed mould are limited by the achievable pressure differential, which restricts the maximum height and size of the rotor blade, leading to inefficiencies in resin consumption, manufacturing time, and potential resin pooling issues.
Innovation Solution
The use of a composite moulding assembly that applies a uniform cavity overpressure within the mould interior, combined with resin overpressure, to enhance resin distribution and prevent pooling, allowing for increased resin infusion height and reduced resin consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resin overpressure is applied to increase infusion rate, then resin distribution is improved, but resin pooling occurs in lower regions
Solution Approach 1:
The patent applies cavity overpressure (positive pressure in the mould cavity) to counteract the harmful effect of resin pooling. By changing the pressure parameter from simple resin overpressure to combined resin overpressure plus cavity overpressure, the system achieves both fast infusion and prevents resin pooling in lower regions.
Solution Approach 2:
The cavity overpressure acts as an intermediary force that mediates between the resin overpressure (which drives infusion) and the gravitational force causing resin pooling. This intermediate pressure mechanism allows the system to benefit from high resin pressure while eliminating the harmful pooling effect.
2Manufacturing precision
If vacuum pressure is increased to improve resin distribution, then infusion uniformity is improved, but achievable pressure differential is limited to 1 bar
Solution Approach 1:
The patent changes the pressure differential parameter from vacuum-only (limited to 1 bar) to combined vacuum plus cavity overpressure. This parameter change enables the system to achieve the desired resin distribution uniformity while overcoming the limitation of achievable pressure differential.
Solution Approach 2:
Instead of relying solely on vacuum pressure to drive resin infusion, the system copies the effective pressure differential mechanism by adding cavity overpressure. This allows the system to achieve higher effective pressure differentials while maintaining uniform resin distribution.
3Loss of time
If resin pressure is increased to speed up infusion, then manufacturing time is reduced, but resin pools form and cause exothermic temperature issues
Solution Approach 1:
The cavity overpressure serves as an intermediary that allows high resin pressure to be applied during infusion (reducing manufacturing time) while preventing the formation of resin pools that would cause excessive exothermic temperatures during curing.
Solution Approach 2:
The system converts the potentially harmful effect of high resin pressure (which causes pooling and temperature issues) into a beneficial fast infusion process by introducing cavity overpressure. The cavity overpressure allows the system to achieve fast infusion speeds while eliminating the harmful thermal consequences.
4Strength
If closed mould technique is used to eliminate joint weaknesses, then structural strength is improved, but resin infusion uniformity becomes more difficult to achieve
Solution Approach 1:
The patent applies cavity overpressure as an additional parameter to the closed mould resin infusion process. This parameter change enables the system to achieve uniform resin distribution throughout the entire layup while maintaining the structural strength benefits of the closed mould technique.
Solution Approach 2:
The cavity overpressure is applied continuously throughout the resin infusion process in the closed mould, ensuring continuous and uniform resin distribution. This continuous application of overpressure maintains the integrity of the closed mould approach while achieving the desired resin infusion uniformity.
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
This approach enables faster resin infusion, reduced manufacturing time, and lighter composite structures with improved structural strength, while overcoming size limitations and enabling larger rotor blades with increased power output.
Implementation Method 1
a vacuum arrangement comprising a number of vacuum bags arranged to separate the layup from a mould interior cavity, and a means of extracting air from the layup through the air extraction ports
Implementation Method 2
The wetting cycle time is determined by a number of factors, primarily by the pressure differential during infusion, i.e. the difference between resin pressure and the vacuum pressure in the layup
Implementation Method 3
The resin pressure shall be understood as the pressure measured at the lowest level of the layup at a point along the mould (since the lowest layup level may vary along the mould, the resin pressure and the pressure differential are variables)
Implementation Method 4
a means of creating an overpressure in the mould interior cavity... The cavity overpressure is uniform throughout the cavity in the layup interior, i.e. the cavity overpressure acts uniformly against the entire interior surface of the layup
Implementation Method 5
A resin pool (appearing as excess liquid resin collecting under the vacuum bag) causes problems in the exothermic curing process, since the resulting high temperature in the excess resin can melt various process materials such as the vacuum bag
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention describes a composite moulding assembly (1) comprising a mould (10) for receiving a layup (20), a number of resin inlets and resin channels (108) arranged about the mould (10), and a number of air extraction ports (104) arranged about the mould (10); a resin infusion arrangement configured to convey resin (110) to the resin inlets; a vacuum arrangement comprising a number of vacuum bags (120) arranged to separate the layup (20) from a mould interior cavity (10C), and a means (12, 122) of extracting air from the layup (20); and a cavity overpressure arrangement (13, 132) configured to create a cavity overpressure (P10C) in the mould interior cavity (10C) during a resin infusion procedure. The invention further describes a method of moulding a composite (2) using such a composite moulding assembly (1); and a wind turbine rotor blade (2) manufactured using such a composite moulding assembly (1).