Composite Thermo-Hydroforming Manufacturing Process for Thermoplastic Composite Laminates
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. Currently, there has been little or no use of hydroforming in the production of composites. However, there is a need for a forming and shaping method that can produce complex composite structures with as little wrinkling or tearing as possible.
Description of Technology
Michigan State University’s technology is a method to apply hydroforming manufacturing to the processing of shaping composite materials. To produce a hydroformed composite part, a diaphragm 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.
An improvement of the hydroforming apparatus covered in U.S. Patent No. 6,631,630, this patent pending punch die apparatus works with polymer composite materials and metals. Thermo-hydroforming blanks use a vacuum-sealed outer film to form complex deep-drawn geometries. The apparatus and methods provide a fast and efficient means for part manufacturing with smooth outer surfaces.
- 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.
- Automotive: body/frame structures and other metal replacement options
- Defense: metal decking/railing replacement or removable armor
- Energy: fuel cells, membrane components, and wind turbine blades
Patent Pending and U.S. patent 6,631,630 (TEC2000-0025)
Farhang Pourboghrat, Nicholas Kuuttila
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Michigan State University