Expandable Tooling Systems And Methods

What is this patent about?

’892 is related to the field of manufacturing composite parts, specifically addressing the challenge of curing fiber-reinforced polymer composites. Traditional methods often rely on autoclaves to apply heat and pressure, but this can create bottlenecks due to autoclave capacity and transportation requirements. The patent addresses the need for alternative, "Out of Autoclave" (OOA) curing processes that can achieve comparable quality without the limitations of autoclaves.

The underlying idea behind ’892 is to use an expandable element within a constraining container to apply pressure to an uncured composite workpiece during curing. The workpiece is supported by a rigid form inside the container, and the expandable element, initially unexpanded, is introduced into the remaining volume. By triggering a predetermined change in the element's attribute (e.g., temperature), it expands, pressing against both the container walls and the workpiece, thereby consolidating the composite material as it cures.

The claims of ’892 focus on a method of manufacturing a composite workpiece. This involves adding foamable pellets to the space around an uncured composite workpiece inside a container. These pellets are designed to expand when a specific attribute changes, such as temperature. This expansion generates pressure on the workpiece, which is supported by a rigid form, and the composite is cured under this pressure.

In practice, the foamable pellets, often made of a thermoplastic material with a blowing agent, are placed inside the container alongside the uncured composite part. As the container is heated, the pellets expand, exerting pressure on the composite. This pressure ensures proper consolidation of the composite layers during the curing process. The container is designed to be minimally larger than the workpiece, minimizing the amount of expandable material needed.

This method differentiates itself from traditional autoclave curing by eliminating the need for large, specialized equipment. The use of expandable pellets allows for a more flexible and adaptable tooling system, particularly useful for manufacturing components with complex shapes or at remote locations. Furthermore, the patent explores various enhancements, such as using volumetrically invariant adjuncts to optimize pressure distribution and contractible elements to facilitate pellet removal after curing, improving the overall efficiency and effectiveness of the OOA curing process. The use of heat-generating substances inside the container is also discussed as a way to eliminate the need for external heating.