MSU Technologies

Composite Thermo-Hydroforming Manufacturing Process for Thermoplastic Composite Laminates

Executive Summary

In hydroforming, a metal blank is formed into a desired shape with the use of fluid pressure impinging on the blank which in turn impinges on a die that gives the blank its final shape. Hydroforming has a number of advantages when compared to other shaping processes, including reduced tooling cost, increased drawability, and enhanced stability. However, currently, there has been little or use of hydroforming in the production of composites. MSU innovators have developed a process for hydroforming that that can produce complex composite structures with as little wrinkling or tearing as possible.

Description of Technology

The technology to produce a hydroformed composite part involves a diaphragm that is lowered onto the blank and an initial fluid pressure is applied that deforms it onto the retracted punch piece. The punch is then extended, forcing the blank material between the punch piece and the pressurized "forming chamber" created as the diaphragm deforms. The punch continues to extend and draw the part until the desired depth and other dimensions are achieved. Next, the diaphragm pressure is relieved, and the diaphragm and punch piece are retracted, leaving the formed part to cool and be processed further. The even hydrostatic pressure applied by the diaphragm helps prevent fiber wrinkling and other defects. In addition, the diaphragm support also provides more uniform part thickness control and reduces the propensity for part thinning or "necking" as is common in other material drawing processes.

Key Benefits

Higher part complexity: The technology provides flexible cross-section choices as well as the ability to mix materials, fiber types, sheets, and weaves.
Expanded part type capability: More diverse design choices are available due to deeper draw capability.

Lower tooling costs: The diaphragm-punch arrangement avoids the need for a matched high-strength steel die set, thereby reducing tooling requirements.
Reduced residual stress: Reduced post-forming and cooling deformation.
Lower defect rate: Reduced wrinkling, displacement, ruptures, and other forming defects.

Applications